EP3880624A1

EP3880624A1 - Heat-treated material having low resistivity and improved mechanical properties

Info

Publication number: EP3880624A1
Application number: EP19835446.6A
Authority: EP
Inventors: Denis Guimard; Johann SKOLSKI; Joël BELLEMIN
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2018-11-16
Filing date: 2019-11-15
Publication date: 2021-09-22
Also published as: WO2020099802A1; MX2021005392A; US20220002191A1; CO2021006353A2; FR3088635A1; US11565968B2; FR3088635B1

Abstract

The invention relates to a material comprising a transparent substrate coated with a thin-film stack comprising at least one silver-based functional metal film, at least one zinc-based metal film positioned above and/or below a silver-based functional metal film, and at least one nickel oxide-based film positioned above and/or below said silver-based functional metal film and separated from said film by at least one crystallised dielectric film.

Description

LOW RESISTIVITY AND PROPERTIES THERMALLY TREATED MATERIAL

IMPROVED MECHANICS

The invention relates to a material comprising a transparent substrate coated with a stack of thin layers comprising at least one functional metallic layer based on silver. The invention also relates to glazing comprising these materials as well as the use of such materials for manufacturing glazing for thermal insulation and / or sun protection.

The functional metallic layers based on silver (or silver layers) have advantageous electrical conduction and infrared (IR) reflection properties, hence their use in so-called "solar control" glazing intended to reduce the amount of incoming solar energy and / or in so-called "low-emissivity" glazing aimed at reducing the amount of energy dissipated outside a building or a vehicle.

These silver layers are deposited between coatings based on dielectric materials generally comprising several dielectric layers (hereinafter "dielectric coatings") making it possible to adjust the optical properties of the stack. These dielectric layers also make it possible to protect the silver layer from chemical or mechanical attack.

The optical and electrical properties of materials depend directly on the quality of the silver layers such as their crystalline state, their homogeneity and their environment. The term “environment” is understood to mean the nature of the layers near the silver layer and the surface roughness of the interfaces with these layers.

To improve the quality of the functional metallic layers based on silver, it is known to use dielectric coatings comprising dielectric layers with stabilizing function intended to promote the wetting and nucleation of the silver layer. In particular, dielectric layers based on crystallized zinc oxide are used for this purpose. In fact, the zinc oxide deposited by the sputtering process crystallizes without requiring additional heat treatment. The zinc oxide layer can therefore serve as an epitaxial growth layer for the silver layer.

For the same purpose, it is also known to use blocking layers located between a functional layer and a dielectric coating, the function of which is to protect these functional layers from possible degradation during deposition of the upper dielectric coating and / or during heat treatment. Many possibilities varying in particular by the nature, the number and the position of said blocking layers have been proposed. The invention relates more particularly to stacks which have to undergo a heat treatment at high temperature such as annealing, bending and / or quenching.

Generally speaking, heat treatments at high temperatures can make stacks more susceptible to scratches. On the other hand, when scratches are created on a material before heat treatment, their visibility increases considerably after heat treatment.

The applicant has observed that stacks comprising, near a silver layer, both blocking layers chosen from certain materials and / or certain thicknesses and dielectric layers comprising zinc, in particular based on oxide of zinc or based on zinc oxide and tin, exhibit, following the heat treatment, advantageously improved scratch resistance properties and disadvantageously degraded resistivity.

These phenomena seem partly linked to modifications within the silver layer induced by the migration of species during the heat treatment. These changes affect not only the visual appearance but also the optical properties and the electrical conductivity of the stack.

The reasons and mechanisms for migrating species are still poorly understood. Their occurrence seems to be highly dependent on the nature of the blocking layers and of the dielectric layers constituting the dielectric coatings located near the silver layer. The presence of certain dielectric materials in the stack, in particular of certain oxides, or of certain blocking layers, favors the migration of certain species, in particular the salting out of metallic zinc elements near the silver layer, via the reduction dielectric layers comprising zinc.

The improvement in scratch resistance could be due to doping of the silver layer with zinc.

The deterioration in resistivity could be due to the presence of metallic zinc elements or to defects linked to zinc located at the upper or lower interface of the silver layer and / or at the grain boundary of the silver layer. .

The presence of metallic zinc elements in the layer seems to improve durability at the expense of resistivity.

On the strength of this observation, the applicant was interested in the effects of the voluntary insertion of a metallic layer based on zinc in fragile stacks from the point of view of resistance to scratches and intended to undergo a heat treatment. The objective is to obtain, by directly adding the metallic zinc elements, the positive effect on the scratch resistance. By doing so, improvement no longer depends the creation of mobile species of metallic zinc by reduction of the layer comprising zinc.

The Applicant has thus surprisingly discovered that the insertion of a zinc-based metal layer not only significantly improves the scratch resistance of the silver stacks, but also drastically reduces hot corrosion and the cold corrosion in humid environments.

These improvements are, however, accompanied by a deterioration in resistivity and absorption.

This solution consisting simply in adding a metallic layer based on zinc is not fully satisfactory, the aim is to obtain low light absorption and low emissivity.

The objective of the present invention is to develop a material which, after a heat treatment (s) at high temperature, has both low resistivity and therefore low emissivity, moderate absorption and excellent mechanical properties resulting in excellent scratch resistance.

The applicant has surprisingly discovered that the joint presence of a zinc-based metal layer and a nickel oxide-based layer near a silver-based layer makes it possible to achieve these Goals.

The invention therefore relates to a material comprising a transparent substrate coated with a stack of thin layers comprising at least one functional metallic layer based on silver and at least two dielectric coatings, each dielectric coating comprising at least one dielectric layer, so each functional metal layer is placed between two dielectric coatings,

characterized in that the stack comprises:

- at least one metallic layer based on zinc, situated above and / or below a functional metallic layer based on silver,

- At least one layer based on nickel oxide situated above and / or below this functional metallic layer based on silver and separated from this layer by at least one crystallized dielectric layer.

According to a particularly advantageous embodiment, a crystallized dielectric layer based on zinc oxide is located below and in contact with the layer based on nickel oxide.

The zinc-based metal layer is in a dielectric coating in contact with said functional silver-based metal layer. This means that the zinc-based metal layer is not separated from said metal layer functional based on silver by another functional metallic layer based on silver.

The presence of a layer of metallic zinc near the silver layer causes during the heat treatment the migration of metallic zinc elements in the silver layer following the heat treatment.

The migration of metallic zinc elements into the silver layer following the heat treatment makes it possible to improve the scratch resistance after heat treatment regardless of the structure of the stack. The zinc-based metal layer therefore improves mechanical resistance.

The presence of a layer based on nickel oxide makes it possible to completely suppress the degradation of the resistivity and to reduce in part the increase in absorption, normally induced by the metallic layer based on zinc.

It is particularly interesting to note that the layer based on nickel oxide makes it possible to restore the degraded properties without losing the advantageous properties induced by the metallic layer based on zinc.

Indeed, the solution of the invention makes it possible to significantly improve the scratch resistance of silver stacks, but also to drastically reduce hot corrosion and cold corrosion in wet environments.

Therefore, the present invention is suitable for all applications using stacks comprising functional silver-based layers intended to be heat treated and where it is sought to improve the mechanical properties and in particular the scratch resistance.

The very favorable effect on the reduction of resistivity is obtained when the layer based on nickel oxide is not directly in contact with this functional metallic layer based on silver.

The invention therefore allows the development of a material comprising a substrate coated with a stack comprising at least one functional metallic layer based on silver having, following a heat treatment of the bending, quenching or annealing type:

- a lower ability to be scratched and

- significantly improved resistance to hot and cold corrosion,

- maintaining a low resistivity,

- moderate increase in absorption.

The solution of the invention is suitable in the case of stacks with several functional layers based on silver, in particular stacks with two or three functional layers which are particularly fragile from the point of view of scratches.

The present invention is also suitable in the case of stacks with a single functional layer based on silver intended for applications where the stacks are highly prone to cold corrosion in a humid environment. This is particularly the case with single glazing comprising stacks with a single layer of silver used as glazing for a refrigerator door.

The invention also relates to:

- glazing comprising a material according to the invention,

- glazing comprising a material according to the invention mounted on a vehicle or on a building, and

- the process for preparing a material or a glazing according to the invention,

- the use of glazing according to the invention as solar control glazing and / or low emissivity for the building or vehicles,

- a building, a vehicle or a device comprising glazing according to the invention.

Throughout the description, the substrate according to the invention is considered to be laid horizontally. The stack of thin layers is deposited on top of the substrate. The meaning of the expressions "above" and "below" and "lower" and "higher" should be considered in relation to this orientation. In the absence of a specific stipulation, the expressions "above" and "below" do not necessarily mean that two layers and / or coatings are arranged in contact with each other. When it is specified that a layer is deposited “in contact” with another layer or a coating, this means that there cannot be one (or more) layer (s) interposed between these two layers (or layer and coating).

All the luminous characteristics described are obtained according to the principles and methods of the European standard EN 410 relating to the determination of the luminous and solar characteristics of the glazing used in glass for construction.

Glazing for the building generally delimits two spaces, a space qualified as "exterior" and a space qualified as "interior". The sunlight entering a building is considered to go from the outside to the inside.

According to the invention, the light characteristics are measured according to the illuminant D65 at 2 ° perpendicular to the material mounted in a double glazing:

- TL corresponds to the light transmission in the visible in%,

- Rext corresponds to the external light reflection in the visible in%, observer on the outside space side,

- Rint corresponds to the interior light reflection in the visible in%, observer on the interior space side,

- a ^* T and b ^* T correspond to the colors in transmission a ^* and b ^* in the L ^* a ^* b ^{* system} ,

- a ^* Rext and b ^* Rext correspond to the colors in reflection a ^* and b ^* in the L ^* a ^* b ^{* system} , observer on the outside space side, - a ^* Rint and b ^* Rint correspond to the colors in reflection a ^* and b ^* in the L ^* a ^* b ^{* system} , observer on the interior space side.

The preferred characteristics which appear in the following description are applicable both to the material according to the invention and, where appropriate, to the glazing or to the process according to the invention.

The stack is deposited by sputtering assisted by a magnetic field (magnetron process). According to this advantageous embodiment, all the layers of the stack are deposited by sputtering assisted by a magnetic field.

Unless otherwise stated, the thicknesses mentioned in this document are physical thicknesses and the layers are thin layers. The term “thin layer” is intended to mean a layer having a thickness of between 0.1 nm and 100 micrometers.

According to a particularly advantageous embodiment, a crystallized dielectric layer based on oxide, in particular based on zinc oxide, can be located below the layer based on nickel oxide, preferably in contact.

According to a particularly advantageous embodiment, the stack can comprise the sequence:

- a crystalline oxide-based layer, and in particular a zinc oxide-based layer,

a layer based on nickel oxide situated above and in contact with the crystallized layer based on zinc oxide, and

- a crystallized oxide-based layer, and in particular a zinc oxide-based layer, located above and in contact with the nickel oxide-based layer.

This sequence can be found above and / or below the functional silver-based metallic layer.

According to a particularly advantageous embodiment, the dielectric coating located directly below the functional metallic layer based on silver comprises at least one crystallized dielectric layer based on oxide, in particular based on zinc oxide, optionally doped using at least one other element, such as aluminum. Advantageously, the crystallized dielectric layer based on oxide, in particular based on zinc oxide, can be located:

- between the functional metallic layer based on silver and the layer based on nickel oxide, preferably in contact with the nickel oxide layer and / or in contact with the functional metallic layer based on silver , and or

- below the layer based on nickel oxide, preferably in contact.

When the layer based on nickel oxide is situated above a crystallized dielectric layer, in particular based on zinc oxide, this crystallized layer underlying allows good crystallization of the nickel oxide layer by growth by epitaxy above the crystallized layer.

In fact, nickel oxide, unlike zinc oxide, does not crystallize very well when cold under the conditions of deposition of the conventional cathode sputtering, that is to say under vacuum at room temperature, unless it is deposited on a crystallized layer such as a layer of zinc oxide. The combination in the stack of a crystallized layer of zinc oxide below a layer based on nickel oxide makes it possible to crystallize the layer of nickel oxide.

Good crystallization of the nickel oxide layer has two advantages.

The first is the decrease in absorption induced by the nickel oxide layer. A well crystallized layer is less absorbent.

The second advantage is that if a crystallized layer is deposited on top of the nickel oxide-based layer, the nickel oxide layer influences to some extent the crystallization of this overlying layer. .

Indeed, the nickel oxide-based layer can be located below, preferably in contact with, a crystallized dielectric layer traditionally used as a wetting layer for the functional silver-based layer. In this case, the nickel oxide-based layer influences to a certain extent the crystallization of this so-called wetting crystallized layer, which layer then in turn influences the crystallization of the overlying silver-based layer. .

In the optimal configuration, the layer based on nickel oxide is located between two crystallized dielectric layers, for example based on zinc oxide. The lower crystallized dielectric layer acts as a seed layer for the nickel oxide-based layer, making it less absorbent. The nickel oxide layer acts to a lesser extent as a growth layer for the upper crystallized dielectric layer. The upper crystallized dielectric layer acts as a growth and wetting layer for the silver layer.

The solution of the invention makes it possible to obtain low square resistance values in particular of the same order, or even lower, than those obtained for materials not comprising the metallic layer based on zinc. For this, the thickness of the layer based on nickel oxide must be optimized as a function of the stack and in particular as a function of the thickness of the metal layer based on zinc and the presence or absence of a layer of blocking.

Finally, surprisingly, a decrease in absorption is observed despite the increase in the thickness of the layers based on nickel oxide. The solution of the invention therefore makes it possible to significantly lower the absorption but does not not allow to obtain values as low as those obtained with materials without a metallic layer based on zinc and without a layer based on nickel oxide.

One possible explanation is as follows.

The presence of a layer of metallic zinc near the silver layer causes during the heat treatment the migration of metallic zinc elements in the silver layer following the heat treatment. As explained above, it is attributed to the migration of these metallic zinc elements in the agent layer during the heat treatment, the improvement of the mechanical resistance and the degradation of the resistivity and of the absorption.

It is probable that the layer based on nickel oxide makes it possible to a certain extent to attract to it all or part of the metallic zinc elements having migrated in the silver layer and being at the interfaces or between the grain boundaries of the silver layer. This elimination allows to find excellent resistivity values and to lower the absorption.

This explanation is corroborated by the study of the visibility of the scratches. The determination of the visibility of the stripes takes into account the optical properties of the stack and more particularly the reflection properties of the striped parts of the stack.

The examples show that excellent scratch resistance is obtained for nickel oxide layer thicknesses between 1 and 3 nm, which results in small widths of scratches.

Finally, the migration conditions for metallic zinc elements:

- from the zinc-based metal layer to the silver layer or

- from the silver layer to the nickel oxide layer,

may be different. Indeed, they depend on the nature of the layers nearby but also on the temperature of the heat treatment.

One explanation would be that only a small proportion of metallic zinc contributes to the improvement of mechanical properties. The remaining metallic zinc which does not participate in the improvement of the mechanical properties is likely to degrade the resistivity. However, this remaining zinc is "pumped" by the layer based on nickel oxide, thus preventing degradation of the resistivity.

In the following paragraphs, the zinc-based metal layers are defined as they are obtained during deposition, that is to say before heat treatment. Insofar as the heat treatment induces the migration of metallic zinc elements in the stack, it is not possible to determine with certainty, according to the thicknesses deposited, how this layer of metallic zinc is modified following the heat treatment. The term “metallic layer” means a layer comprising not more than 30%, 20% or 10% of oxygen and / or nitrogen in atomic percentage in the layer.

The layers are deposited in metallic form. Following deposition and before heat treatment, they should not contain more than 10% oxygen and / or nitrogen. However, depending on the nature of the layer deposited directly above, these zinc-based metal layers are liable to undergo partial oxidation which can lead to higher proportions of oxygen or nitrogen. These proportions are however less than 30 or 20%. In any event, at least part of the thickness of these zinc-based metal layers is not oxidized or nitrided.

Zinc-based metal layers (before heat treatment) include at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80% , at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% by mass of zinc relative to the mass of the metallic layer based on zinc .

The zinc-based metal layers can be chosen from:

- metallic zinc layers,

- doped metallic zinc layers,

- metallic layers based on zinc alloy.

According to the invention, the term “metallic zinc layer” is understood to mean metallic layers of pure zinc which may still include some impurities. In this case, the total mass of zinc represents at least 99% by mass of the mass of the zinc-based metal layer.

According to the invention, the doped zinc layers comprise at least 90.0%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% by mass of zinc of the mass of the zinc-based metal layer.

The doped zinc layers can be chosen from layers based on zinc and at least one element chosen from titanium, nickel, aluminum, tin, niobium, chromium, magnesium, copper, silicon, silver or gold.

According to the invention, the zinc alloy-based layers comprise at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80% or at least 90% by mass of zinc of the mass of the metallic layer based on zinc.

The layers based on zinc alloy can be chosen from layers based on zinc and at least one element chosen from titanium, nickel, chromium, tin. By way of example, mention may be made of binary zinc and titanium alloys such as Zn ₂ Ti or ternary alloys based on zinc, nickel and chromium such as ZnNiCr. The thickness of the zinc-based metal layer is between 0.2 and 10 nm. The thickness of the zinc-based metal layer can be:

- greater than or equal to 0.2 nm, greater than or equal to 0.5 nm, greater than or equal to 1.0 nm, greater than or equal to 1.2 nm, or greater than or equal to 1.5 nm, greater than or equal to 2 nm and / or

- less than or equal to 10 nm, less than or equal to 8 nm, less than or equal to 7 nm, less than or equal to 6 nm, less than or equal to 5 nm or less than or equal to 4 nm.

The zinc-based metal layer can be located above and / or below a silver-based functional metal layer, directly in contact or separated by one or more layers from the functional metal-based layer. silver.

Preferably, the zinc-based metal layer (s) are located above the functional silver-based metal layer.

Nickel oxide layers include at least 20%, at least

30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% by mass of nickel relative to the total mass of all the elements constituting the layer based on nickel oxide with the exception of oxygen and nitrogen.

The layers based on nickel oxide can comprise one or more elements chosen from chromium, titanium, aluminum or molybdenum.

The nickel oxide-based layer may comprise at least 1%, at least 2%, at least 5%, at least 8%, at least 10%, at least 15%, at least 20%, at least 30% , at least 40%, at least 50%, at least 60%, at least 70%, at least 80% by mass of elements other than nickel relative to the total mass of all the elements constituting the base layer d nickel oxide excluding oxygen and nitrogen.

A priori, the layer based on nickel oxide is not nitrided, however traces may exist.

The nickel oxide-based layer comprises, in ascending order of preference, at least 80%, at least 90%, at least 95%, at least 98%, at least 100%, by mass of oxygen relative to the total mass of oxygen and nitrogen.

The layer or layers based on nickel oxide have a thickness of between 0.2 and 10.0 nm, or even between 0.6 and 8.0 nm, or even between 1.0 and 5.0 nm.

The thickness of a layer based on nickel oxide, for example can be:

- greater than or equal to 0.2 nm, greater than or equal to 0.5 nm, greater than or equal to 1.0 nm, greater than or equal to 1.2 nm, greater than or equal to 1.5 nm, greater than or equal to 2.0 nm, greater than or equal to 2.5 nm or greater than or equal to 3.0 nm and / or

- less than or equal to 10 nm, less than or equal to 8 nm, less than or equal to 7 nm, less than or equal to 6 nm, less than or equal to 5 nm or less than or equal to 4 nm, less than or equal to 3 nm, less than or equal to 2 nm, less than or equal to 1 nm.

The thickness of the single or all the layers separating the layer based on nickel oxide and the functional metallic layer based on silver is between 0.5 and 15.0 nm, or even between 0.7 and 8.0 nm, or even between 1.0 and 6.0 nm.

The layer based on nickel oxide can be chosen from a layer of nickel and chromium oxide (NiCrOx), a layer of nickel and titanium oxide (NiTiOx) or a layer of nickel oxide and d aluminum (NiAIOx).

Preferably, a layer of nickel and chromium oxide comprises, in ascending order of preference, relative to the total mass of all the elements constituting the layer based on nickel oxide excluding oxygen and nitrogen:

- at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 75% by mass of nickel, and / or

- at least 60%, at least 50%, at least 40%, at least 30%, at least 25%, at least 20%, at least 15%, at least 10%, at least 5%, by mass of chromium .

Preferably, a layer of nickel and titanium oxide comprises, in ascending order of preference, relative to the total mass of all the elements constituting the layer based on nickel oxide excluding oxygen and nitrogen:

- at least 40%, at least 50%, at least 60%, at least 70%, at least 75% by mass of nickel, and / or

- at least 60%, at least 50%, at least 40%, at least 30%, at least 25%, at least 20%, at least 15%, at least 10%, at least 5%, by mass of titanium .

Preferably, a layer of nickel and aluminum oxide comprises, in ascending order of preference, relative to the total mass of all the elements constituting the layer based on nickel oxide excluding oxygen. and nitrogen:

- at least 60%, at least 50%, at least 40%, at least 30%, at least 25%, at least 20%, at least 15%, at least 10%, at least 5%, by mass of aluminum.

According to the invention, the crystallized dielectric layers correspond to the dielectric layers also called “stabilizing layer” or “wetting”. By stabilizing layer is meant a layer made of a material capable of stabilizing the interface with the functional layer. These layers are generally based on zinc oxide. Zinc oxide layers may include at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% by mass of zinc relative to the total mass of all the elements constituting the zinc oxide-based layer excluding oxygen and l 'nitrogen.

To be correctly crystallized by sputtering deposition, the zinc oxide-based layers advantageously comprise at least 80%, or even at least 90% by mass of zinc relative to the total mass of all the elements constituting the base layer zinc oxide excluding oxygen and nitrogen.

The layers based on zinc oxide can comprise one or more elements chosen from aluminum, titanium, niobium, zirconium, magnesium, copper, silver, gold, silicon, molybdenum, nickel, chromium, platinum, indium, tin and hafnium, preferably aluminum.

The zinc oxide layers can optionally be doped with at least one other element, such as aluminum.

A priori, the zinc oxide-based layer is not nitrided, however traces may exist.

The zinc oxide-based layer comprises, in increasing order of preference, at least 80%, at least 90%, at least 95%, at least 98%, at least 100%, by mass of oxygen relative to the total mass of oxygen and nitrogen.

The thickness of a layer based on zinc oxide can for example be:

- greater than or equal to 1 nm, greater than or equal to 2 nm, greater than or equal to 3 nm, greater than or equal to 4 nm, greater than or equal to 5 nm, greater than or equal to 6 nm, greater than or equal to 7 nm, greater than or equal to 8 nm or greater than or equal to 9 nm, and / or

- less than or equal to 25 nm, less than or equal to 20 nm, less than or equal to 15 nm, less than or equal to 13 nm, less than or equal to 12 nm, less than or equal to

11 nm, less than or equal to 10 nm, less than or equal to 9 nm, less than or equal to 8 nm.

The crystalline oxide-based dielectric layer, in particular based on zinc oxide, may be in contact with the nickel oxide layer and / or in contact with the functional metallic layer based on silver.

The metallic functional layers based on silver can be “protected” by a layer qualified as a blocking layer. A blocking layer above a functional silver-based metal layer is called a blocking overlay. A blocking layer below a functional silver-based metallic layer is called a blocking undercoat. The stack can comprise at least one blocking overlay, preferably located immediately in contact with the functional metallic layer based on silver.

The stack may comprise at least one blocking under layer, preferably located immediately in contact with the functional metallic layer based on silver.

The blocking layers are chosen from metallic layers based on a metal or a metal alloy, metallic nitride layers, metallic oxide layers and metallic oxynitride layers of one or more elements chosen from titanium, nickel, chromium, tantalum and niobium such as Ti, TiN, TiOx, Nb, NbN, Ni, NiN, Cr, CrN, NiCr, NiCrN.

When these blocking layers are deposited in metallic, nitrided or oxynitrided form, these layers can undergo partial or total oxidation depending on their thickness and the nature of the layers which surround them, for example, at the time of deposition of the next layer or by oxidation on contact with the underlying layer.

The blocking layers can be chosen from metallic layers, in particular an alloy of nickel and chromium (NiCr) or titanium.

Advantageously, the blocking layers are metallic layers based on nickel. Nickel-based metallic blocking layers may include, (before heat treatment), at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% by mass of nickel relative to the mass of the metallic base layer of nickel.

The nickel-based metal layers can be chosen from:

- metallic nickel layers,

- doped nickel metal layers,

- metallic layers based on nickel alloy.

The metal layers based on nickel alloy can be based on alloy of nickel and chromium.

Each blocking layer has a thickness of between 0.1 and

5.0 nm. The thickness of these blocking layers can be:

- at least 0.1 nm, at least 0.2 nm, at least 0.5 nm and / or

- not more than 5.0 nm, not more than 4.0 nm, not more than 3.0 nm, not more than 2.0 nm.

The metallic layer based on zinc and the layer based on nickel oxide can be:

- separated by the functional metallic layer based on silver,

- located above the functional silver-based metallic layer,

- located below the functional silver-based metallic layer. Preferably, the zinc-based metal layer (s) are located above a silver layer and above a blocking overlay. In this configuration, the zinc-based metal layer is located above the functional silver-based metal layer and is separated from this layer by at least one blocking overlay.

However, other configurations are possible.

The zinc-based metal layer can be located:

- above a functional metallic layer based on silver, the metallic zinc layer is in contact with the functional metallic layer based on silver (Ag / Zn sequence),

- above a functional metallic layer based on silver, the metallic zinc layer is separated from the functional metallic layer based on silver by at least one blocking overlay (sequence Ag // Blocking layer // Zn),

- above a functional metallic layer based on silver and below and in contact with a crystallized dielectric layer, the layer of metallic zinc is in contact with the functional metallic layer based on silver (sequence Ag / Zn / Crystallized layer),

- above a functional metallic layer based on silver and below and in contact with a crystallized dielectric layer, the layer of metallic zinc is separated from the functional metallic layer based on silver by at least one overlayer blocking (Ag sequence // Blocking layer // Zn // Crystallized layer),

- above a functional metallic layer based on silver and above, and in contact with a crystallized dielectric layer, the crystallized dielectric layer is optionally separated from the functional metallic layer based on silver by at least a blocking overlay (Ag sequence // possibly Blocking layer // Crystallized layer / Zn),

- below a functional metallic layer based on silver, the metallic zinc layer is in contact with the functional metallic layer based on silver (Zn / Ag sequence),

- below a functional metallic layer based on silver, the metallic zinc layer is separated from the functional metallic layer based on silver by at least one blocking under layer (sequence Zn // Blocking layer / / Ag),

- below a functional metallic layer based on silver and above and in contact with a crystallized dielectric layer, the layer of metallic zinc is in contact with the functional metallic layer based on silver (layer sequence crystallized / Zn / Ag),

- below a functional metallic layer based on silver and above and in contact with a crystallized dielectric layer, the layer of metallic zinc is separated from the functional metallic layer based on silver by at least one blocking under layer (sequence Crystallized layer / Zn // Blocking layer // Ag),

- below a functional metallic layer based on silver and below, and in contact with a crystallized dielectric layer, the crystallized dielectric layer is in contact with or separated from the functional metallic layer based on silver by at least one blocking sublayer (Zn sequence / crystallized layer // possibly blocking layer.//Ag).

The thickness of all the possible layers separating the layer based on metallic zinc and the functional layer is between 0 and 15.0 nm, even between 0 and 10 nm, even between 0 and 5 nm.

The thickness of all the layers separating the functional metallic layer based on silver from the metallic layer based on zinc can be:

- greater than or equal to 0.2 nm, greater than or equal to 0.4 nm, greater than or equal to 0.5 nm, greater than or equal to 1 nm, greater than or equal to 2 nm, greater than or equal to 3 nm, greater or equal to 4 nm, greater than or equal to 5 nm, greater than or equal to 6 nm, greater than or equal to 7 nm, greater than or equal to 8 nm or greater than or equal to 9 nm and / or

- less than or equal to 25 nm, less than or equal to 20 nm, less than or equal to 15 nm, less than or equal to 13 nm, less than or equal to 12 nm, less than or equal to 11 nm, less than or equal to 10 nm , less than or equal to 9 nm or less than or equal to 8 nm, less than or equal to 7 nm, less than or equal to 6 nm, less than or equal to 5 nm, less than or equal to 4 nm, less than or equal to 3 nm, less than or equal to 2 nm, less than or equal to 1.5 nm.

The thickness of all the layers separating the functional metallic layer based on silver from the metallic layer based on zinc can be between 0.2 and 5 nm, between 0.5 and 3 nm, between 0, 8 and 1.5 nm.

All the configurations according to which the metallic layer based on zinc is situated above and not directly in contact with the functional metallic layer based on silver have, for an optimized thickness, a resistivity before heat treatment not degraded compared to a stack not comprising the zinc-based metal layer.

According to the invention, an undegraded resistivity is understood to mean a variation in resistivity due to the presence of the zinc layer not more than 15%, preferably not more than 10%.

The configuration that the zinc-based metal layer is located above and separated from the silver-based functional metal layer by a blocking overlay appears to give the best results. The configuration in which the zinc-based metal layer is located above and separated from the silver-based functional metal layer by a blocking overlay and a crystallized layer also gives good results.

It is also possible to use in these configurations a blocking under layer. The use of a blocking underlay allows to improve the mechanical resistance. A blocking sublayer situated below a silver layer and a zinc-based metallic layer situated above and directly in contact with said silver layer or separated from the silver layer are then combined. by a crystallized layer and / or by a blocking overlay.

The following is an explanation of the beneficial effect of having a blocking overlay or blocking undercoat near the silver layer.

The silver layers are polycrystalline layers, that is to say composed of a plurality of monocrystalline grains of silver. During the heat treatment, a rearrangement takes place leading to a decrease in the number of grains and an increase in the size of the grains.

It is possible that the metallic zinc species diffuse very efficiently in the stack, that is to say at temperatures below the temperatures at which this rearrangement occurs.

Take the case where the zinc-based metal layer is located above the silver layer. If the metallic zinc elements diffuse at these lower temperatures, in the absence of a blocking overlay, they could easily pass through the silver layer without being sufficiently retained. In this case, the effect on the modification of the mechanics and the resistivity would be less.

On the other hand, when a blocking overlay is inserted between the silver and zinc layers, the blocking layer could act as a barrier and slow down the diffusion of metallic zinc elements. This would keep metallic zinc elements in the silver layer when the higher silver layer rearrangement temperatures are reached. The metallic zinc elements would then be retained near the silver layer. This would explain the significant impact of the presence of the blocking layer on the mechanical properties and on the resistivity.

To a lesser extent, the use of a blocking underlayer also performs the function of preventing the diffusion of metallic zinc elements and confining them near the silver layer. Configurations according to this embodiment can be advantageous.

The configurations in which the zinc-based metal layer is located below and near the silver-based functional metal layer, have a resistivity before degraded heat treatment. One possible explanation is that the zinc layer under the silver layer increases the roughness of the lower interface of the silver layer. This is observed when the zinc-based metal layer is located in contact with a functional silver-based metal layer or separated from this functional silver-based metal layer by at least one blocking sublayer.

According to the invention, the term “layer located near” means a layer located, in order of preferably increasing within 15 nm, within 10 nm, within 5 nm, within 4 nm, at less than 3 nm, less than 2 nm from another layer.

The following embodiments are advantageous:

- the zinc-based metal layer is located near the silver layer and / or

the metallic layer based on zinc and the layer based on nickel oxide are separated by the silver layer, and / or

- the zinc-based metal layer is located above the silver layer,

- the zinc-based metal layer is located above the silver layer and the nickel oxide-based layer is located below the silver layer.

Zinc-based metal layers, to be effective, must allow the diffusion of metallic zinc elements towards the silver layer. It is likely that if these zinc layers are separated from the silver layer:

- by one or more dielectric layers which are too thick, for example layers of zinc oxide and tin which are too thick and / or

- by one or more dielectric layers with barrier function such as layers of silicon nitrides and / or aluminum and / or zirconium,

the diffusion of these metallic zinc elements will be greatly reduced or even prevented. The zinc-based metal layer then becomes ineffective from the point of view of improving mechanical properties.

It seems that the crystallized layers do not prevent the migration of metallic zinc elements. However, simply because of their thickness, the presence of such layers slows down this migration. Preferably, zinc-based metal layers are separated from the silver layer by blocking layers and / or crystallized layers.

According to the invention, the stack comprises at least one functional metallic layer based on silver.

The functional metallic layer based on silver, before or after heat treatment, comprises at least 95.0%, preferably at least 96.5% and better still at least 98.0% by mass of silver relative to the mass of the functional layer. Preferably, the functional metallic layer based on silver before heat treatment comprises less than 1.0% by mass of metals other than silver relative to the mass of the functional metallic layer based on silver.

After heat treatment, the functional metallic layer based on silver is likely to include a proportion of zinc. A measurement of the zinc doping can be carried out for example by microprobe analysis of Castaing (ElectroProbe MicroAnalyzer or EPMA in English) or by measurement by atomic tomographic probe ("Atom Probe Tomography").

The thickness of the silver-based functional layer is from 5 to 25 nm.

The stack of thin layers comprises at least one functional layer and at least two dielectric coatings comprising at least one dielectric layer, so that each functional layer is placed between two dielectric coatings.

The stack of thin layers can comprise at least two functional metallic layers based on silver and at least three dielectric coatings comprising at least one dielectric layer, so that each functional layer is placed between two dielectric coatings.

The stack of thin layers can comprise at least three functional layers and at least four dielectric coatings comprising at least one dielectric layer, so that each functional layer is placed between two dielectric coatings.

The invention is not limited to the insertion of a single metallic layer based on zinc. It is obviously possible to have a metallic layer based on zinc near at least two functional layers based on silver, or even each functional layer based on silver.

A stack can therefore comprise one or more metallic layers based on zinc.

A stack comprising at least two metallic functional layers based on silver may comprise at least two metallic layers based on zinc near at least two metallic functional layers based on silver.

It is also possible, in multi-functional silver-based stacks, that each silver-based metallic functional layer is in proximity to a zinc-based metallic functional layer.

The stack is located on at least one of the faces of the transparent substrate.

By “dielectric coating” within the meaning of the present invention, it should be understood that there may be a single layer or several layers of different materials inside the coating. A "dielectric coating" according to the invention mainly comprises dielectric layers. However, according to the invention these coatings can also comprise layers of other nature, in particular absorbent layers, for example metallic layers.

We consider that the same dielectric coating is located:

- between the substrate and the first functional layer,

- between each functional layer,

- above the last functional layer (furthest from the substrate).

By "dielectric layer" in the sense of the present invention, it should be understood that from the point of view of its nature, the material is "non-metallic", that is to say is not a metal. In the context of the invention, this term designates a material having an n / k ratio over the entire wavelength range of the visible (from 380 nm to 780 nm) equal to or greater than 5. n denotes the index of actual refraction of the material at a given wavelength and k represents the imaginary part of the refractive index at a given wavelength; the n / k ratio being calculated at a given given wavelength for n and for k.

The thickness of a dielectric coating corresponds to the sum of the thicknesses of the constituent layers.

The coatings have a thickness greater than 15 nm, preferably between 15 and 200 nm.

The dielectric layers of the coatings have the following characteristics, alone or in combination:

- they are deposited by sputtering assisted by magnetic field,

- they are chosen from the oxides or nitrides of one or more elements chosen from titanium, silicon, aluminum, zirconium, tin and zinc,

- They have a thickness greater than or equal to 2 nm, preferably between 2 and 100 nm.

Preferably, the dielectric coating located directly below the functional metallic layer based on silver comprises at least one crystallized dielectric layer as defined above, in particular based on zinc oxide, optionally doped using at least one other element, such as aluminum.

In all stacks, the dielectric coating closest to the substrate is called the bottom coating and the dielectric coating furthest from the substrate is called the top coating. Stacks with more than one silver layer also include intermediate dielectric coatings located between the upper and lower coating.

Preferably, the lower or intermediate coatings comprise a crystallized dielectric layer based on zinc oxide situated directly in contact with the metallic layer based on silver or separated by a blocking under layer. Preferably, the intermediate or upper coatings comprise a crystallized dielectric layer based on zinc oxide situated directly in contact with the metallic layer based on silver or separated by a blocking overlay.

The zinc oxide layers have a thickness:

- at least 1.0 nm, at least 2.0 nm, at least 3.0 nm, at least 4.0 nm, at least 5.0 nm, and / or

- not more than 25 nm, not more than 10 nm, not more than 8.0 nm.

The dielectric layers can have a barrier function. By dielectric layers with barrier function is meant (hereinafter barrier layer), a layer of a material capable of forming a barrier to the diffusion of oxygen and water at high temperature, originating from the ambient atmosphere or from the substrate. transparent, towards the functional layer. Such dielectric layers are chosen from the layers:

- based on silicon and / or aluminum and / or zirconium compounds chosen from oxides such as Si02, nitrides such as silicon nitride Si3N4 and aluminum nitrides AIN, and oxynitrides SiOxNy, optionally doped using at least one other element,

- based on zinc oxide and tin,

- based on titanium oxide.

Preferably, each coating comprises at least one dielectric layer consisting of:

- of an aluminum and / or silicon and / or zirconium nitride or oxynitride or

- a mixed zinc and tin oxide, or

- of a titanium oxide.

Preferably, each dielectric coating comprises at least one dielectric layer with a barrier function based on an aluminum nitride and / or silicon and / or zirconium. Preferably, the sum of the thicknesses of all the barrier function dielectric layers based on an aluminum nitride and / or silicon and / or zirconium in each dielectric coating is greater than or equal to 15 nm, or even greater than or equal at 20 nm.

These dielectric layers have, in increasing order of preference, a thickness:

- less than or equal to 40 nm, less than or equal to 30 nm, less than or equal to 25 nm, and / or

- greater than or equal to 5 nm, greater than or equal to 10 nm or greater than or equal to 15 nm.

The stack of thin layers may optionally include a protective layer. The protective layer is preferably the last layer of the stack, that is to say the layer furthest from the substrate coated with the stack (before heat treatment). These layers generally have a thickness of between 0.5 and 10 nm, preferably 1 and 5 nm. This protective layer can be chosen from a layer of titanium, zirconium, hafnium, silicon, zinc and / or tin, this or these metals being in metallic, oxidized or nitrided form.

According to one embodiment, the protective layer is based on zirconium oxide and / or titanium, preferably based on zirconium oxide, titanium oxide or titanium oxide and zirconium.

The substrate coated with the stack or the stack only is intended to undergo a heat treatment. However, the present invention also relates to the coated substrate which is not heat treated.

The stack may not have undergone a heat treatment at a temperature above 500 ° C, preferably 300 ° C.

The stack may have been heat treated at a temperature above 300 ° C, preferably 500 ° C.

The heat treatments are chosen from annealing, for example by rapid thermal annealing ("Rapid Thermal Process") such as laser annealing or flash lamp, quenching and / or bending. Rapid thermal annealing is for example described in application WO2008 / 096089.

The heat treatment temperature (at the stack) is greater than 300 ° C, preferably greater than 400 ° C, and better still greater than 500 ° C.

The substrate coated with the stack may be a curved or tempered glass.

The transparent substrates according to the invention are preferably made of a rigid mineral material, such as glass, or organic polymers (or polymer).

The transparent organic substrates according to the invention can also be made of polymer, rigid or flexible. Examples of polymers suitable according to the invention include, in particular:

- polyethylene,

- polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN);

- polyacrylates such as polymethyl methacrylate (PMMA);

- polycarbonates;

- polyurethanes;

- polyamides;

- polyimides;

- fluorinated polymers such as fluoroesters such as ethylene tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluorethylene (PCTFE), chlorotrifluorethylene ethylene (ECTFE), fluorinated ethylene-propylene copolymers (FEP);

- photocrosslinkable and / or photopolymerizable resins, such as thiolene, polyurethane, urethane-acrylate, polyester-acrylate resins and

- polythiourethanes.

The substrate is preferably a sheet of glass or glass ceramic.

The substrate is preferably transparent, colorless (it is then a clear or extra-clear glass) or colored, for example in blue, gray or bronze. The glass is preferably of the soda-lime-silica type, but it can also be made of borosilicate or alumino-borosilicate type glass.

According to a preferred embodiment, the substrate is made of glass, in particular silica-soda-lime or of polymeric organic material.

The substrate advantageously has at least one dimension greater than or equal to 1 m, even 2 m and even 3 m. The thickness of the substrate generally varies between 0.5 mm and 19 mm, preferably between 0.7 and 9 mm, in particular between 2 and 8 mm, or even between 4 and 6 mm. The substrate can be flat or curved, or even flexible.

The invention also relates to a glazing unit comprising at least one material according to the invention. The invention relates to glazing which can be in the form of monolithic, laminated or multiple glazing, in particular double glazing or triple glazing.

A monolithic glazing has 2 faces, the face 1 is outside the building and therefore constitutes the exterior wall of the glazing, the face 2 is inside the building and therefore constitutes the interior wall of the glazing.

Multiple glazing comprises at least one material according to the invention and at least one additional substrate, the material and the additional substrate are separated by at least one interlayer of gas. The glazing creates a separation between an exterior space and an interior space.

Double glazing has 4 sides, side 1 is outside the building and therefore constitutes the outer wall of the glazing, side 4 is inside the building and therefore constitutes the inner wall of the glazing, sides 2 and 3 being inside the double glazing.

A laminated glazing unit comprises at least one structure of the first substrate / sheet (s) / second substrate type. The polymer sheet can in particular be based on polyvinyl butyral PVB, ethylene vinyl acetate EVA, polyethylene terephthalate PET, polyvinyl chloride PVC. The stack of thin layers is positioned on at least one of the faces of one of the substrates.

These glazings can be mounted on a building or a vehicle.

These glazings can be mounted on devices such as oven or refrigerator doors. The following examples illustrate the invention.

Examples I. Preparation of the substrates: Stacks, deposition conditions

Stacks of thin layers defined below are deposited on clear soda-lime glass substrates with a thickness of 2 or 4 mm.

In the examples of the invention:

- the functional layers are silver layers (Ag),

- the blocking layers are metallic layers of nickel and chromium alloy (NiCr),

- the layers based on nickel oxide NiOx are based on nickel and chromium,

- the dielectric layers are based on silicon nitride, doped with aluminum (Si ₃ N ₄ : Al) and zinc oxide (ZnO).

The conditions for depositing the layers, which have been deposited by sputtering (so-called “cathodic magnetron sputtering”), are summarized in Table 1.

The tables below list the materials and the physical thicknesses in nanometers (unless otherwise indicated) of each layer or coating which constitutes the stacks as a function of their positions with respect to the substrate carrying the stack.

II. Evolution of square resistance and absorption

The square resistance Rsq, corresponding to the resistance reported on the surface, is measured by induction with a Nagy SMR-12.

The square resistance and the absorption were measured before heat treatment (BT) and after heat treatments at a temperature of 650 ° C for 10 min (AT).

The variation in resistivity was determined as follows:

ARsq _(AT vs. _BT) = (RsqAT-RsqBT) / RsqBT X 100. a. Influence of the thickness of the nickel oxide-based layer

The table below shows the square resistance results obtained for coated substrates, after heat treatment at 650 ° C., as a function of the thickness of the layer based on nickel oxide.

The use of a zinc-based metal layer significantly degrades the resistivity (comparison of Ref. 1 and Ref. 2).

For materials comprising a layer of nickel oxide (Emp.1-1 to 1-5), the resistivity gradually decreases for thicknesses of layer of nickel oxide between 1 and 3 nm. Then, these values remain almost constant for greater thicknesses.

The use of a layer based on nickel oxide of 3 nm makes it possible to return to square resistance values of the same order as those obtained for materials not comprising the metallic layer based on zinc (comparison of Ref. 1 and Emp. 1-3). b. Stacks without a blocking layer

The table below shows the results of square resistance and absorption obtained for coated substrates, before and after quenching.

3T: Before heat treatment, AT: after heat treatment.

The material ref. 1 (without a zinc-based metal layer and without a nickel-oxide layer) has an equal resistivity gain of around 30% after heat treatment at 650 ° C.

The material ref. 2 (with a zinc-based metal layer and without a nickel oxide-based layer) has an emissivity and absorption that is severely degraded following the heat treatment. The comparison of materials Ref.1 and Ref.2 shows a loss of resistivity. This results in negative ARsq values and represents a fall from +30% to -12%. Absorption increases from 7 to 13%.

When a layer of nickel oxide is added to the dielectric coating below the silver layer, the gain in resistivity gradually increases with increasing thicknesses of nickel oxide layers.

The Emp.1-1 material has a resistivity gain of 12%.

The Emp.1-3 material has a gain of around 30%. The gain and the square resistance are equivalent to those of Ref. 1.

The solution of the invention makes it possible to obtain low resistivity values, in particular as low as those obtained with materials without a layer of metallic zinc and without a layer based on nickel oxide.

The absorption decreases gradually for increasing thicknesses of nickel oxide-based layers. The material Emp.1-3 has an absorption of 10%, a decrease of 3% compared to Ref.2.

Unlike the resistivity, the solution of the invention makes it possible to significantly lower the absorption but does not make it possible to obtain values as low as those obtained with materials without a metallic layer based on zinc and without a layer based on nickel oxide.

A possible explanation could be that the layer based on nickel oxide allows to a certain extent to attract to it all or part of the metallic zinc elements having migrated in the silver layer and being at the interfaces or between the joints of grain of the silver layer. This elimination makes it possible to find excellent resistivity values and to lower the absorption. vs. Stacks with a sub-blocking layer The table below shows the results of square resistance and absorption obtained for coated substrates, before and after quenching.

BT: Before heat treatment, AT: after heat treatment.

The presence of a metallic layer based on zinc generates a degradation of the gain in resistivity normally observed following a heat treatment.

When the stack comprises a blocking under layer and comprises a metallic layer based on zinc (Ref. 4), a gain in resistivity of 4% is observed. The example Ref. 3 comprising a blocking under layer and not comprising a zinc layer has a gain of 33%.

The resistivity is however significantly less degraded when the stack comprises a blocking under layer. Indeed, in the presence of a blocking under layer, the impact of the incorporation of a zinc-based metal layer is less severe on the resistivity after heat treatment (comparison Ref. 2 and Ref. 3, ARsq respectively 4% and -12%)

In the same way as for materials without a blocking under layer, the layer based on nickel oxide makes it possible to completely recover the gain in resistivity (Ref. 3 and Emp. 2, ARsq of 33%).

III. Mechanical properties

Erichsen tests at Pointe (EST) under the following conditions were carried out:

- EST: This test consists in applying a point (Van Laar point, steel ball) at a given force (in Newton) to make a scratch in the stack and possibly to transfer the width of the stripes. The EST test (without any other qualifier) is carried out without heat treatment.

- EST-TT: This test consists in carrying out an EST test followed by a heat treatment under the following conditions: Applied force: 0.3 N, 0.5 N, 0.8 N, 1 N, 3 N or 5 N ; Heat treatment, 10 minutes at a temperature of 650 ° C,

- TT-EST: This test consists of carrying out a heat treatment followed by an EST test under the following conditions: Heat treatment, 10 minutes at a temperature of 650 ° C; Applied force: 0.3 N, 0.5 N, 0.8 N, 1 N, 3 N or 5 N. a. Stacks without a blocking layer The table below shows the results of the TT-EST Test after a heat treatment at 650 ° C and reports the measurements of the width of the scratches in pm with an applied force of 0.8 N.

Materials ref. 1 (without zinc-based metal layer and without nickel-oxide-based layer) and ref. 2 (with a zinc-based metal layer and without a nickel-oxide layer) have a stripe width of 20 μm and 14 μm respectively in the 0.8 N TT-EST test. A similar trend for the width of the scratches are also observed in the TT-EST 3 N test. A decrease in the visibility of scratches is also observed (comparison Ref. 1 and Ref. 2). The use of a zinc-based metal layer significantly improves the scratch resistance.

The solution of the invention combining a layer of metallic zinc and a layer based on nickel oxide makes it possible to obtain excellent scratch resistance.

The comparison between Ref. 2 (comprising only a layer based on zinc oxide) and Emp. 1-3 according to the invention, shows a very slight slight increase in the width of stripes, respectively for the TT tests. -EST at 0.8 and 0.3 N, from 14 and 34 pm (Ref. 2) to 16 to 35 pm (Emp.1-3). This increase is very small, especially if we compare the width of the stripes at TT-EST to 0.8 and 0.3 N from Ref. 1 which is 20 and 47 pm respectively.

The addition of a layer based on nickel oxide in the dielectric coating located below the silver layer therefore makes it possible to preserve the advantageous mechanical properties observed in the presence of a metallic layer based on zinc (comparison with Ref. 2).

These examples show that excellent scratch resistance is obtained for nickel oxide layer thicknesses between 1 and 3 nm, which results in small scratch widths. In alternative embodiments, an improvement could be observed for smaller thickness ranges. b. Stacks with a layer of under block

The TT-EST and EST-TT tests were performed for Emp.2 stacking. The results are similar to those obtained with the Emp stack. 1-3. Consequently, the use of a blocking under layer does not harm the obtaining of the positive effect of the insertion of a metallic layer based on zinc.

IV. Microscopic observations: Hot corrosion

The morphology of the layers is analyzed by light microscopy. Images of the scratches after EST at 1 and 5 N and heat treatment at 650 ° C (EST-TT) were taken.

Figures 1-a, 1 -b, 1-c, 1 -d, 1-e, 1-f are images taken under the microscope of scratches made after indentation with a force of 1 or 5 N followed by heat treatment.

The scratches, when present, are much finer for the material comprising a metallic layer based on zinc (Ref. 2 and Emp.1-3) than for the material Ref. 1. Above all, the scratches of the materials comprising a metallic layer based on zinc are not corroded at all.

The addition of the layer based on nickel oxide does not prevent the advantageous effects linked to the presence of the metal layer based on zinc. The images following the EST-TT test clearly show that the striped parts of the stack comprising both a layer based on nickel oxide and a metal layer based on zinc are not corroded.

This demonstrates that the beneficial effect of the zinc-based metal layer on the resistance to hot corrosion is maintained even when a layer of nickel oxide is added to the stack.

V. Microscopic observation: Cold corrosion

High humidity tests (HH test) were carried out. These tests consist in placing the materials for 5 and 20 days at 90% humidity and 50 ° C. The materials tested are ref. 1, Ref. 2 and stacking 1-3. The tests were carried out on non-heat treated materials (BT) and on heat treated materials (AT). The table above indicates whether corrosion points (Pts corr.) Are observed. The following assessments are given: - "0": no corrosion points,

- "+": some corrosion points,

- "++": visible corrosion points,

- "+++": Lots of corrosion points.

FIG. 2 includes optical images showing the visibility of corrosion after 5 and 20 days of HH test on non-heat treated materials and after 20 days of HH test on heat treated materials.

FIG. 3 includes optical images showing the defects due to corrosion after 5 days of HH test for the reference material Ref. 1 not heat treated (3-a) and heat treated (3-b).

BT: Before heat treatment, AT: After heat treatment, "-": no image.

The Ref. 1 stack without heat treatment has corrosion defects visible to the eye after 5 days of HH test (Fig. 2-a and 3-a). The density of the corrosion points increases after 20 days of HH test (Fig. 2-b).

For materials comprising a metallic layer based on zinc without heat treatment, the presence of a metallic layer based on zinc limits the formation of corrosion points (fig. 2-d, 2-e and 2-g, 2- h). No corrosion points are observed after 5 days and only a few points after 20 days. The addition of a zinc-based metal layer significantly increases the resistance to cold corrosion for heat treated or untreated materials.

The Ref. 1 heat treated becomes completely hazy after 20 days (fig. 2-c). The characterization under an optical microscope after 5 days (fig. 3-b) shows a very high density of microscopic scale defects in addition to the large corrosion defects already observed for the non-heat treated material (fig.2-a).

For materials according to the invention heat treated, the presence of a zinc-based metal layer prevents the formation of haze linked to cold corrosion.

In conclusion, the addition of a layer based on nickel oxide makes it possible to maintain the excellent resistance to cold corrosion observed in the presence of a metallic layer based on zinc (comparison with Ref. 2). After 20 days of HH test, the materials according to the invention, treated or not heat treated, have little or no corrosion or haze points (fig. 2-h, 2-i) unlike the material of Ref. 1 (fig. 2-b, 2-c). Thanks to the incorporation of a zinc-based metal layer, a significant improvement in the resistance to cold corrosion is observed both on heat-treated and non-heat-treated materials.

VI. Conclusion

The solution of the invention makes it possible to obtain low resistivity values, in particular of the same order as those obtained for materials not comprising the layer based on zinc oxide (comparison of Ref. 1 and Emp. 1-3) . For this, the layer based on nickel oxide should preferably have a thickness greater than or equal to 0.5 nm, greater than or equal to 1 nm, 2 nm, 2.5 nm, or 3 nm. However, in alternative embodiments, improvement could be observed for smaller ranges of nickel oxide layer thickness.

The solution of the invention makes it possible to significantly lower the absorption but does not make it possible to obtain values as low as those obtained with materials without a layer of metallic zinc and without a layer based on nickel oxide (comparison Emp. 1-3, and ref. 1 Ref. 2).

The solution of the invention makes it possible both to obtain excellent scratch resistance but also to completely restore low resistivity and to obtain moderate absorption. The addition of a layer based on nickel oxide makes it possible to retain the advantageous mechanical properties observed in the presence of a metallic layer based on zinc (comparison with Ref. 2).

The solution of the invention makes it possible to significantly improve the resistance to hot corrosion. Indeed, the observation following the EST-TT test clearly shows that the striped parts of the stack comprising both a layer based on nickel oxide and a metal layer based on zinc are not corroded. The beneficial effect of the zinc-based metal layer on the resistance to hot corrosion is maintained even when a layer of nickel oxide is added to the stack.

Finally, the solution of the invention makes it possible to significantly improve the resistance to cold corrosion. The addition of a layer based on nickel oxide makes it possible to maintain the excellent resistance to cold corrosion observed in the presence of a metallic layer based on zinc. The materials according to the invention, treated or not heat treated, have little or no corrosion or blurring.

The positive effect on resistivity, absorption, mechanical resistance, resistance to hot corrosion and resistance to cold corrosion is obtained in the presence and absence of a sub-blocking layer in contact with the layer. silver.

Claims

1. Material comprising a transparent substrate coated with a stack of thin layers comprising at least one functional metallic layer based on silver and at least two dielectric coatings, each dielectric coating comprising at least one dielectric layer, so that each functional metal layer is placed between two dielectric coatings, characterized in that the stack comprises:

2. Material according to claim 1, characterized in that the stack comprises a crystallized dielectric layer based on zinc oxide located below and in contact with the layer based on nickel oxide.

3. Material according to any one of the preceding claims, characterized in that the dielectric coating located directly below the functional metallic layer based on silver comprises a crystallized dielectric layer based on zinc oxide, located between the silver functional metal layer and the nickel oxide based layer, preferably in contact with the nickel oxide layer and / or in contact with the silver based functional metal layer.

4. Material according to any one of the preceding claims, characterized in that the layer based on nickel oxide is located in the dielectric coating located directly below the functional metallic layer based on silver.

5. Material according to any one of the preceding claims, characterized in that the stack comprises the sequence:

- a crystalline oxide-based layer, and in particular a zinc oxide-based layer,

- a layer based on nickel oxide situated above and in contact with the crystallized layer based on zinc oxide, and

6. Material according to any one of the preceding claims, characterized in that the layer or layers based on nickel oxide have a thickness of between 0.2 and 10.0 nm.

7. Material according to any one of the preceding claims, characterized in that the thickness of the single or of all the layers separating the layer based on nickel oxide and the functional metallic layer based on silver is included between 0.5 and 15.0 nm, or even between 0.7 and 8.0 nm, or even between 1.0 and 6.0 nm.

8. Material according to any one of the preceding claims, characterized in that the stack comprises at least one blocking layer, in particular an overlay and / or a blocking under layer, located immediately in contact with the functional metallic layer based on silver.

9. Material according to claim 8, characterized in that the blocking layer or layers are chosen from metallic layers based on a metal or a metal alloy, metallic nitride layers, metallic oxide layers and the layers of metallic oxynitride of one or more elements chosen from titanium, nickel, chromium, tantalum and niobium.

10. Material according to any one of the preceding claims, characterized in that the metallic layer based on zinc and the layer based on nickel oxide are separated by the functional metallic layer based on silver.

11. Material according to any one of the preceding claims, characterized in that the zinc-based metal layer is located above the silver-based functional metal layer.

12. Material according to any one of the preceding claims, characterized in that the zinc-based metal layer is located above the silver-based functional metal layer and is separated from this layer by at least one overlay of blocking.

13. Material according to any one of the preceding claims, characterized in that the physical thickness of all the layers separating the layer based on metallic zinc and the functional layer is between 0 and 15.0 nm, or even between 0 and 10 nm, or even between 0 and 5 nm.

14. Material according to one of the preceding claims, characterized in that the thickness of the zinc-based metal layer is between 0.2 and 10 nm.

15. Material according to one of the preceding claims, characterized in that the zinc-based metal layers comprise at least 20% by mass of zinc relative to the mass of the zinc-based metal layer.

16. Material according to any one of the preceding claims, characterized in that each dielectric coating comprises at least one dielectric layer with a barrier function based on an aluminum nitride and / or silicon and / or zirconium.

17. Material according to any one of the preceding claims, characterized in that the stack has not undergone a heat treatment at a temperature above 500 ° C, preferably 300 ° C.

18. Material according to any one of claims 1 to 16 characterized in that the stack has undergone a heat treatment at a temperature above

300 ° C, preferably 500 ° C.

19. Material according to any one of the preceding claims, characterized in that the substrate is made of glass, in particular silica-soda-lime or of polymeric organic material.

20. Glazing comprising a material according to any one of claims 1 to 19 characterized in that it is in the form of monolithic, laminated or multiple glazing, in particular double glazing or triple glazing.