FR2924232A1 - SUBSTRATE EQUIPPED WITH A THERMAL PROPERTY STACK - Google Patents

Abstract

The invention relates to a glass substrate (10) provided on a main face with a stack of thin layers comprising a functional metallic layer (40) with reflection properties in the infrared and / or in solar radiation, in particular at base of silver or a metal alloy containing silver, and two anti-reflective coatings (20, 60), said coatings each comprising at least one dielectric layer (24, 64) based on silicon nitride, said functional layer ( 40) being disposed between the two anti-reflective coatings (20, 60), the functional layer (40) being deposited directly on a sub-blocking coating (30) disposed between the functional layer (40) and the anti-reflective coating (20) under -jacent and the functional layer (40) being deposited directly under an over-blocking coating (50) disposed between the functional layer (40) and the overlying antireflection coating (60), characterized in that for said substrate to be bendable and / or tr stackable after the deposition of the stack of thin layers, the stack comprises a thin nickel-based layer in the underblocking coating (30) and / or in the overblocking coating (50), said thin layer nickel-based being deposited at a high vacuum pressure, equal to or greater than 2.10 <-3> Torr, and preferably between 2.5.10 <-3> Torr and 5.10 <-3> Torr.

Description

SUBSTRATE EQUIPPED WITH A THERMAL PROPERTY STACK

The invention relates to a transparent substrate made of a rigid mineral material such as glass, said substrate being coated with a stack of thin layers comprising a functional layer of metallic type capable of acting on solar radiation and / or infrared radiation of great length. wave. The invention relates more particularly to the use of such substrates for manufacturing thermal insulation and / or solar protection glazing. These glazing can be intended both to equip buildings and vehicles, in particular with a view to reducing the air conditioning effort and / or preventing excessive overheating (so-called solar control glazing) and / or reducing the quantity of energy. dissipated to the outside (so-called low-emissive glazing) caused by the ever-increasing importance of glazed surfaces in buildings and vehicle interiors. These glazings can moreover be integrated into glazings having particular functionalities, such as, for example, heated glazing or electrochromic glazing.

A type of stack of layers known to give substrates such properties consists of a functional metallic layer with reflection properties in the infrared and / or in solar radiation, in particular a metallic functional layer based on silver or metal alloy containing silver.

The known type of stack to which the invention relates is referred to as a slot and blocker stack because it has the following structure, in this order: Substrate / underlying anti-reflective coating / sub-blocker coating / functional metal layer / coating on -blocker / overlying anti-reflective coating + optionally a protective layer. -2- The functional layer is thus placed between two antireflection coatings each generally comprising a single layer which is made of a dielectric material of the silicon nitride type. The purpose of these coatings which surround the metallic functional layer is to antireflect this metallic functional layer. However, a blocking coating is interposed between each anti-reflective coating and the functional metal layer. The blocking coating placed under the functional layer in the direction of the substrate promotes the crystal growth of this layer and protects it during any heat treatment at high temperature, of the bending and / or tempering type. The blocking coating placed on the functional layer opposite the substrate protects this layer from possible degradation during the deposition of the upper antireflection coating and during a possible high temperature heat treatment, of the bending and / or toughening type. The present invention relates more specifically to a stack of the type of that presented above which is resistant to the heat treatment of bending and / or toughening applied to the glass substrates in order to allow them to be bulged and / or to be soaked.

A person skilled in the art distinguishes two categories of stacks resistant to the heat treatment (or supporting a heat treatment) of bending and / or tempering: 1- the so-called toughening stacks which do not exhibit the desired and expected characteristics before the heat treatment, in particular of light transmission, color, resistivity, etc. and which acquire them during this heat treatment; the substrates coated with this type of stack cannot therefore be used as such by the end user (when conditioning the substrates to form glazing, for example), but only after having undergone a heat treatment; 2- the so-called bendable and / or hardenable stacks which have acceptable characteristics before the heat treatment and -3- which after heat treatment have similar or almost identical characteristics, that is to say which have variations in characteristics at heat treatments which are acceptable and such that it will be difficult for an observer to distinguish by visual observation coated substrates of the stack which have undergone heat treatment from substrates coated with the same stack which have not undergone heat treatment. It is not possible for those skilled in the art to define these two categories more precisely because, for example, a dipping stack may exhibit a variation in light transmission in the visible to heat treatment as low as a quenching stack but for example a greater variation in light reflection in the visible or a greater variation in color. However, the documents of the prior art and the technical documentations of glassmakers clearly make this distinction and the present invention is only concerned with the second category of stacking, bending and / or hardenable stacks. The invention thus applies to so-called hardenable substrates insofar as it is difficult to distinguish, on the same building facade, for example having glazings in proximity to one another integrating substrates with a stack of thin layers soaked after deposition. layers and substrates with the same stack of unhardened thin layers, by a simple global visual observation of the glazing integrating in particular the light transmission in the visible, the color in reflection and the light reflection in the visible part of the glazing. For those skilled in the art, there are stacks which do not withstand any heat treatment. It is thus known from European patent application No. EP 567 735, a stack of the type presented above in terms of stack structure 30 which cannot undergo heat treatment. -4- In this document EP 567 735 it is explained that it is important for each nickel-based blocking coating to have a thickness of less than 0.7 nanometers. It is also known from European patent application No. EP 646 551, a stack of the same type (same succession of layer, same material for each layer) which, for its part, can undergo heat treatment; it is a stack to be quenched because it exhibits strong variations, in particular optical variations, during the heat treatment of bending or quenching. It is explained in document EP 646 551 that the solution of the preceding document (EP 567 735) cannot undergo heat treatment, probably because the thickness of each blocking coating is not sufficient to properly protect the functional metal layer. silver-based. Document EP 646 551 thus indirectly recommends, in order to produce a stack of the same type but which withstands the heat treatment, that the underblocking coating be really thicker (preferably 2 to 4 times the thickness of the overblocking coating ) and he states in particular that it is preferable that this underblocking coating has a thickness greater than 2 nm and advises a thickness of about 4.5 nm.

Moreover, the invention which is the subject of EP 646 551 is compared with a Standard stack whose optical and thermal characteristics are acceptable and which has, under the metallic functional layer, a blocker layer with a thickness of 0.7 nm deposited under a pressure. of 2.10-3 Torr and which it is said that it does not withstand any heat treatment.

It is explained that this thickness is insufficient and generates holes in the functional metal layer during the heat treatment. It is important to note that this thickness of the nickel-based subblocking coating of the Standard of EP 646 551 is identical to that of the stack of EP 567 735, i.e. 0.7 nm for each of the under and over coatings. -blocking. In EP 567 735 the deposition pressure in the deposition chamber of the nickel-based underblocking coating is not known, but in EP 646,551 the nickel-based subblocking coating is deposited. at very low pressure (1.5.10-3 Torr) and it is stated in this document that the stack of EP 567 735 is reproduced under the same conditions as the stack to be soaked of the invention.

It has been discovered that, surprisingly, it is possible to make this standard stack capable of undergoing heat treatment, that is to say of making the stack to be soaked even when the thickness of the coating is under. -blocking remains low, in particular greater than 0.7 nm, and in any case much less than 2 nm.

Not only can the stack then undergo a heat treatment, but in addition, the variation of these essential properties is so small that it is even possible to make it hardenable.

The aim of the invention is to overcome the drawbacks of the prior art, by developing a new type of stack of layers of the type of those described above, a stack which has a low resistance per square, a light transmission. high and a relatively neutral color, in particular in reflection on the layer side, and that these properties are kept within a restricted range whether the stack undergoes or not, one (or more) heat treatment (s) at high temperature of the type bending and / or tempering and / or annealing. The subject of the invention is thus, in its broadest sense, a glass substrate provided on a main face with a stack of thin layers comprising a metallic functional layer with reflection properties in the infrared and / or in solar radiation. , in particular based on silver or a metal alloy containing silver, and two antireflection coatings, said coatings each comprising at least one dielectric layer based on silicon nitride, said functional layer being arranged between the two antireflection coatings, the functional layer being deposited directly on an underblocking coating disposed between the functional layer and the underlying antireflection coating and the functional layer being deposited directly under an overblocking coating disposed between the functional layer and the coating overlying antireflection, characterized in that for said substrate to be bendable and / or hardenable after deposition of the stack t of thin layers, the stack comprises a thin nickel-based layer in the underblocking coating (30) and / or in the overblocking coating (50), said thin nickel-based layer being deposited at a high vacuum pressure, equal to or greater than 2.10-Torr, and preferably between 2.5.10-3 Torr and 5.10-3 Torr. The invention thus consists in making it possible to manufacture a stack to be soaked, from a Standard stack, of the type of the Standard stack of EP 646 551, which does not withstand heat treatment, with a slight increase in the thicknesses of the layers. blocking coatings and in particular the thickness of the underlocking coating. This advantage is such that it becomes possible to design a stack of the Standard stack type which is hardenable, that is to say whose characteristics and in particular the essential optical characteristics, remain virtually unchanged during the heat treatment. For the purposes of the present invention, when it is specified that a deposit of a layer or coating (comprising one or more layers) is carried out directly under or directly on another deposit, it means that there can be no interposition of 'no layer between these two deposits. The silicon nitride-based layer of the underlying antireflection coating is in contact with the substrate, directly or indirectly via a contact layer, for example based on titanium oxide (TiO2). The index of this nitride-based layer is preferably less than or equal to 2.3, while that of the contact layer is preferably greater than 2.3. The silicon nitride-based layer preferably consists of Si3N4. Although the preceding formula constitutes the target stoichiometry, it is not excluded that this stoichiometry is not completely achieved in the layer finally deposited. The or each thin nickel-based layer preferably having a thickness e such as 1.5 nm e 5 nm, and more preferably 0.8 nm e 1.8 nm. In a particular variant, the thin nickel-based layer of the underblocking coating and the thin nickel-based layer of the overblocking coating have identical or almost identical thicknesses, ie: identical to within 0.2 nm (physical thickness).

The nickel-based thin layer of the underblock coating is preferably directly in contact with the functional layer and the nickel-based thin layer of the overblock coating is preferably directly in contact with the layer. functional. It is not excluded that the underblocking coating and / or the overblocking coating contains (or contains) other layer (s), but then, these other layers will preferably be further away from the functional layer than the thin nickel-based layer. The functional layer is preferably deposited at a high vacuum pressure, equal to or greater than 2.10-3 Torr but however less than 10-2 Torr, and preferably between 2.5.10-3 Torr and 5.10-3 Torr. In fact, the thin layer (s) based on nickel and the functional layer are preferably deposited in the same atmosphere, under the same pressure. In a particular variant, the high vacuum pressure is between 3.10-3 Torr and 4.5.10-3 Torr, and is preferably of the order of 3.5.10-3 Torr. Preferably, the or each thin nickel-based layer comprises at least 50% in atomic proportion of Ni. In a particular version, at least one thin nickel-based layer, and in particular that of the overblocking coating, comprises chromium, preferably in atomic amounts of 80% Ni and 20% Cr. -8- In this particular version, at least one thin nickel-based layer, and in particular that of the overblocking coating, consists of an NiCr alloy present in metallic form if the substrate provided with the stack of layers thin films has not undergone any heat treatment of bending and / or quenching after the deposition of the stack, said alloy being at least partially oxidized if the substrate provided with the stack of thin layers has undergone at least one heat treatment of bending and / or quenching after deposition of the stack. In another particular version, at least one thin nickel-based layer, and in particular that of the overblocking coating, comprises titanium, preferably in atomic amounts of 80% Ni and 20% Ti. In this other particular version, at least one thin nickel-based layer, and in particular that of the overblocking coating, consists of an NiTi alloy present in metallic form if the substrate provided with the stack of thin layers n 'has not undergone any heat treatment of bending and / or quenching after the deposition of the stack, said alloy being at least partially oxidized if the substrate provided with the stack of thin layers has undergone at least one heat treatment of bending and / or quenching after deposition of the stack. The substrate also preferably comprises a last layer (overcoat in English), that is to say a protective layer furthest from the substrate, based on oxide, preferably deposited under stoichiometric, and in particular based of TiOX (where x is a number less than 2). This layer is found essentially stoichiometrically oxidized in the stack after deposition. This protective layer preferably has a thickness of between 1 and 10 nm. The anti-reflective coatings disposed one below the metallic functional layer and the other above each have a physical thickness of between 10 and 50 nm and the metallic functional layer has a physical thickness of between 5 and 50 nm. 20 nm.

The glazing according to the invention incorporates at least the substrate carrying the stack according to the invention, optionally associated with at least one other substrate. Each substrate can be clear or colored. At least one of the substrates, in particular, may be of glass colored in the mass. The choice of the type of coloring will depend on the level of light transmission and / or the colorimetric appearance desired for the glazing once its manufacture has been completed.

Thus for glazing intended to equip vehicles, certain standards require that the windshield has a light transmission TL of approximately 75% and other standards require a light transmission TL of approximately 65%; such a level of transmission is not required for the side windows or the car roof, for example. The tinted glasses that can be used are for example those which, for a thickness of 4 mm, have a TL of 65% to 95%, an energy transmission TE of 40% to 80%, a dominant wavelength in transmission from 470 nm to 525 nm associated with a transmission purity of 0.4% to 6% according to Illuminant D65i which can be translated in the colorimetry system (L, a *, b *) by values of a * and b * in transmission respectively between -9 and 0 and between -8 and +2. For glazing intended to equip buildings, the glazing preferably has a light transmission TL of at least 75% or more for low-emissive glazing applications, and a light transmission TL of at least 40% or more for solar control glazing applications.

The glazing according to the invention can have a laminated structure, combining in particular at least two rigid substrates of the glass type with at least one sheet of thermoplastic polymer, in order to present a structure of the glass / stack of thin layers / sheet (s) / type. glass. The polymer may in particular be based on polyvinylbutyral PVB, ethylene vinyl acetate EVA, polyethylene terephthalate PET, polyvinyl chloride PVC. The glazing may also have a so-called asymmetric laminated glazing structure, associating a rigid substrate of the glass type with at least one sheet of polyurethane-type polymer with energy-absorbing properties, optionally combined with another layer of polymers. with self-healing properties. For more details on this type of glazing, it is possible to refer in particular to patents EP-0 132 198, EP-0 131 523, EP-0 389 354. The glazing can then have a structure of the glass / stack type. thin films / sheet (s) of polymer. The glazing according to the invention is suitable for undergoing a heat treatment without damage to the stack of thin layers. They are therefore possibly convex and / or hardened. The glazing can be curved and / or toughened by being made up of a single substrate, that provided with the stack. It is then a so-called monolithic glazing. In the case where they are curved, in particular with a view to constituting glazing for vehicles, the stack of thin layers is preferably located on an at least partially non-planar face. The glazing can also be a multiple glazing, in particular a double glazing, at least the substrate carrying the stack being able to be curved and / or toughened. It is preferable in a multiple glazing configuration that the stack is arranged so as to face the side of the interlayer gas knife. In a laminated structure, the substrate carrying the stack may be in contact with the polymer sheet. When the glazing is monolithic or multiple of the double glazing or laminated glazing type, at least the substrate carrying the stack may be of curved or tempered glass, this substrate possibly being curved or tempered before or after the deposition of the stack. . The invention also relates to the process for manufacturing the substrates according to the invention, which consists in depositing the stack of thin layers on its substrate by a vacuum technique of the cathode sputtering type, optionally assisted by a magnetic field. -11- It is however not excluded that the first (or the first) layer (s) of the stack may (s) be deposited by another technique, for example by a thermal decomposition technique of the type pyrolysis.

The invention further relates to a method of manufacturing a glass substrate provided on a main face with a stack of thin layers, in particular with the substrate according to the invention, the stack comprising a metallic functional layer with reflection properties in the glass. 'infrared and / or in solar radiation, in particular based on silver or a metal alloy containing silver, and two antireflection coatings, said coatings each comprising at least one dielectric layer based on silicon nitride, said layer functional layer being disposed between the two antireflection coatings, the functional layer being deposited directly on an underblocking coating disposed between the functional layer and the underlying antireflection coating and the functional layer being deposited directly under an overblocking coating disposed between the functional layer and the overlying anti-reflective coating. This process is remarkable in that the stack of thin layers is deposited on the substrate by a vacuum technique of the cathode sputtering type optionally assisted by a magnetic field and in that for said substrate to be bendable and / or hardenable after the deposition of the stack of thin layers, a thin nickel-based layer is deposited in the underblocking coating and / or in the overblocking coating at a high vacuum pressure equal to or greater than 2.10-3 Torr, and preferably between 2.5.10-3 Torr and 5.10-3 Torr. In addition, the functional layer is also preferably deposited at a high vacuum pressure, equal to or greater than 2.10-3 Torr but however less than 10-2 Torr, and preferably between 2.5.10-3 Torr and 5.10- 3 Torr. In fact, the thin layer (s) based on nickel and the functional layer are preferably deposited in the same atmosphere, under the same pressure. This high vacuum pressure is preferably between 3.10-3 Torr and 4.5.10-3 Torr, and is more preferably of the order of 3.5.10-3 Torr. The or each thin nickel-based layer preferably having a thickness e such as 1.5 nm e 5 nm, and more preferably 0.8 nm e 1.8 nm.

The invention further relates to the use of the substrate according to the invention, to produce a substrate which is bendable and / or hardenable after the deposition of the stack of thin layers and which preferably exhibits a variation of light transmission in the visible ATL 5, and preferably ATL 4.5, or even ATL 4 and / or a colorimetric variation in reflection on the stack side and / or on the substrate side: AE 6, and preferably AE 5, or even AE 4.5.

The details and advantageous characteristics of the invention emerge from the following non-limiting examples, illustrated with the aid of the attached figures: FIG. 1 illustrates a functional monolayer stack according to the invention, the functional layer being provided with a coating of underlocking and an overlocking coating and the stack further being provided with an optional protective coating; FIG. 2 illustrates a summary table of the essential optical and thermal characteristics of the examples produced and the variations of these characteristics after heat treatment, as well as the mechanical and chemical characteristics of these examples; and FIG. 3 illustrates a summary table of the essential optical and thermal characteristics of the examples produced after installation in a double glazing unit and the variations of these characteristics after heat treatment then installation in a double glazing unit of identical structure. 30 - 13 - In the figure illustrating stacks of layers, the proportions between the thicknesses of the different materials are not strictly observed in order to facilitate their reading. Moreover, in all the examples below, the stack of thin layers is deposited on a substrate 10 made of soda-lime glass with a thickness of 4 mm. Further, for these examples, in all cases where heat treatment was applied to the substrate, it was annealing for about 5 minutes at a temperature of about 660 ° C followed by cooling down. ambient air (around 20 ° C), in order to simulate a bending or quenching heat treatment. Thus, for each of the examples, when a characteristic was measured before this heat treatment it is classified in the column: BHT and when it was measured after this heat treatment it is classified in the column: AHT. The variation of this characteristic during heat treatment is then indicated by the letter A. A series of tests were carried out. Three examples, numbered 1 to 3, were first made on the basis of the functional single-layer stacking structure illustrated in Figure 1 in which the functional layer 40 is provided with an underblock coating 30 and a coating. 50 respectively immediately below and immediately on the functional layer 40. In this stack, moreover, a lower antireflection coating 20 is deposited immediately under the subblock coating 30 and in contact with the substrate 10 and an upper antireflection coating 60 is deposited immediately on the over-blocking coating 50. In Figure 1 it can be seen that the lower anti-reflective coating 20 has a single anti-reflective layer 24 and the upper anti-reflective coating 60 has a single anti-reflective layer 64, but the anti-reflective coating 60 may be topped with an optional protective coating 70 comprising a thin layer, in particular of oxide. - 14 - Table 1 below illustrates the physical thicknesses (and not the optical thicknesses) in nanometers of each of the layers of Examples 1 to 3: Layer Material Ex. 1 Ex. 2 Ex. 3 70 TiOX 2 2 2 64 Si3N4 45 45 45 50 NiCr 1.5 1.5 2.8 40 Ag 7 7 8, 5 30 NiCr 1.5 3.5 4.2 24 Si3N4 37 37 37 Table 1 The deposition facility used to perform these tests comprises four sputtering chambers fitted with cathodes and fitted with targets made of suitable materials under which the substrate 11 passes successively. These deposition conditions for each of the chambers are as follows: Chamber 1: the layer 24 based on Si3N4 is deposited by reactive sputtering using a silicon target doped with aluminum, under a pressure of 2 , 5 mTorr in an atmosphere composed of 40% argon and 60% nitrogen, - Chamber 2: the NiCr layer of the underlying blocking coating 30 and the NiCr layer of the underlying blocking coating 50 are each deposited using a NiCr alloy target and the silver-based layer 40 is deposited using a silver target, the deposition pressure inside this chamber No. 2 being 3.5 mTorr and the atmosphere being pure argon, - Chamber 3: as in chamber 1, the layer 64 based on Si3N4 is deposited by reactive sputtering using a silicon target doped with aluminum, under a pressure of 2.5 mTorr in an atmosphere composed of 40% argon and 60% nitrogen, - Chamber 4: the protective layer 70 in TiOX is deposited at the using a ceramic target in an atmosphere of 90% argon and 10% oxygen. - 15 - The final stoichiometry of the layer is not known exactly because this layer undergoes additional oxidation once the coated substrate has left the deposition machine and is subjected to the open air and a fortiori during the coating. possible heat treatment.

The power densities and the running speeds of the substrate 10 are adjusted in a known manner to obtain the desired layer thicknesses. It should be noted that each NiCr layer is deposited in metallic form from a metallic target containing 80 atomic% of Ni and 20 atomic% of Cr, in a neutral atmosphere, and that each layer is in a partially oxidized state. in the stack after it has undergone the possible heat treatment.

The optical, mechanical and chemical characteristics of the substrates of these examples are reported in Table 2 of Figure 2 and the optical characteristics of these substrates mounted in double glazing are reported in Table 3 of Figure 3. The structure of the unit of double glazing (DGU) is called 6-15-6, that is to say that the glazing consists of a substrate according to the invention of 6 mm thickness associated with another clear substrate not coated with a thickness of 6 mm, these substrates being separated by an intermediate space with a thickness of 15 mm consisting of 90% argon, the face of the substrate according to the invention being turned towards the intermediate space. In this table, the optical characteristics presented consist of: TLV; S, light transmission TL in the visible in%, measured according to the illuminant D65, A TLV; S, variation in heat treatment of the light transmission TL in the visible, colors in transmission LT *, aT * and bT * in the LAB system measured according to illuminant D65, -16- AET, variation in color heat treatment in reflection on the layer side = (AaT * 2 + ObT * z + OLT * z) rz RLVÎSC, light reflection RL in the visible in%, measured side layers, according to illuminant D65, colors in reflection LRC *, aRc * and bRc * in the LAB system measured according to illuminant D65, layer side, AERC, variation to color heat treatment in reflection on the layer side = (AaRC * 2 + AbRC * 2 + OLRC * 2) Y2 RLV; SS, light reflection RL in the visible in%, measured on the substrate side (side opposite to the stack of layers, according to illuminant D65, reflective colors LRS *, aRs * and bRs * in the LAB system measured according to illuminant D65, layer side, AERS, variation in color heat treatment in reflection on substrate side = (AaRS * 2 + AbRS * 2 + OLRS * 2) Y2 FS, solar factor, calculated according to standard EN 410.

The tests underwent a certain number of mechanical and chemical tests, the performance of which is detailed below: - EBT = Erichsen brush test: this involves rubbing the stack using a bristle brush. polymeric material, the stack being covered with water; the sample has passed the test if no mark is visible to the naked eye and is marked OK. EST = Erichsen test at the Point: this involves reporting the value of the force necessary, in Newton, to produce a scratch in the stack during the performance of the test (Van Laar point, steel ball); here, two tests were carried out, either at 1 N or at 10 N; Taber 500g 100t: this involves transferring the amount of stacking remaining in% of surface area remaining after a Taber test operated after having applied an abrasive roller of 500 g for 100 revolutions; -17- HCL = hydrochloric acid test: this involves immersing a 5x10 cm sample for 8 minutes in an HCl solution (concentration = 0.01M / L) brought to 36 ° C (without stirring). The sample is then rinsed with deionized water, dried, then observed with the eye and with an optical microscope and its optical properties in reflection in the visible side of the layers are measured using a spectrophotometer and compared to those measured. before test. If the observations with the eye and under the microscope do not reveal any defects and the optical variation AE (RL,; Sc) during the test is less than 2, then the sample is considered to resist this test and it carries the mention OK. HH = High humidity test: this involves placing a 10x10cm sample for 5 days in a climatic chamber with a controlled atmosphere (100% humidity and 40 ° C). The observations (eye, microscope) and the measurement of the optical properties after test provide information in the same way as for the HCl test on the resistance or not of the sample to the HH test and the scoring is carried out in the same way.

The stacks of Examples 1 to 3 are hardenable stacks within the meaning of the invention since for each example the variation in light transmission in the visible ATLV; S of the substrates is less than 5 and even equal to or less than 2, the variation in color in reflection on the AERC layer side of the substrates is less than or equal to 6 and the color variation in reflection on the AERS substrate side is less than or equal to 3. It is therefore difficult to distinguish the substrates according to one of Examples 1 to 3 having undergone a treatment. thermal substrates respectively of this same example not having undergone heat treatment, when they are placed side by side. The analysis of Table 2 of FIG. 2 shows that the light transmission in the visible range of Examples 1 to 3 is certainly not very high, but it is nevertheless sufficient for the targeted applications.

It was found that the mechanical strength, both in the Taber test and in the EBT and EST tests of Examples 1 to 3 is very good. The resistance to HCl and HH chemical tests of these examples is also very good.

The mechanical strength of the stack according to the invention can be further improved if a protective layer 70 is provided.

An additional example numbered 1 'has been produced. The stack of this example is identical to that of example 1 except in that the thin nickel-based layer of the overblocking coating 50 is not made of NiCr but of NiTi. As for example 1, it is deposited in metallic form from a metallic target containing 80 atomic% of Ni, in a neutral atmosphere, but unlike example 1, the target contains 20 atomic% of Ti . As in Example 1, the layer is in a partially oxidized state in the stack after the latter has undergone a heat treatment. Before heat treatment, the light transmission in the visible range of the additional example is slightly lower than that of example 1, but the color variation in transmission expressed by AET of the additional example is lower than in the case of Example 1. It is therefore even more difficult to distinguish substrates of the additional example which have undergone heat treatment from the substrates of the additional example which have not undergone heat treatment when they are placed side by side. Furthermore, the general mechanical strength of this stack of the additional example is overall as good as that of example 1 or even slightly better with regard to the EST test. This is all the more astonishing since it is known that for monolayer blocking coatings (the layer having one or more constituents) the metallic layers in Ti generate, for the most part, problems of mechanical strength of the stack. , in particular after heat treatment; scratches may occur in particular during transport between the place where the deposition of the stack on the substrate is operated and the place where the integration of this substrate into a glazing, in particular multiple glazing (double glazing, laminated glazing) is carried out , ...). Furthermore, the general chemical resistance of this stack of the additional example is overall as good as that of example 1.

The present invention is described in the above by way of example. It is understood that a person skilled in the art is able to produce different variants of the invention without, however, departing from the scope of the patent as defined by the claims.

Claims (19)

1. Glass substrate (10) provided on a main face with a stack of thin layers comprising a functional metal layer (40) with reflection properties in the infrared and / or in solar radiation, in particular based on silver or of a metal alloy containing silver, and two anti-reflective coatings (20, 60), said coatings each comprising at least one dielectric layer (24, 64) based on silicon nitride, said functional layer (40) being disposed between the two anti-reflective coatings (20, 60), the functional layer (40) being deposited directly on an underblocking coating (30) disposed between the functional layer (40) and the underlying anti-reflective coating (20) and the layer functional (40) being deposited directly under an overblocking coating (50) disposed between the functional layer (40) and the overlying anti-reflective coating (60), characterized in that for said substrate to be bendable and / or hardenable after filing the stack of thin layers, the stack comprises a thin nickel-based layer in the underblocking coating (30) and / or in the overblocking coating (50), said thin nickel-based layer being deposited at a high vacuum pressure equal to or greater than 2.10-3 Torr, and preferably between 2.5.10'3 Torr and 5.10-3 Torr. 2. Substrate (10) according to the preceding claim, characterized in that the or each thin nickel-based layer having a thickness e such as 1.5nmse5nm. 3. Substrate (10) according to claim 1 or 2, characterized in that the sub-blocking coating (30) and the over-blocking coating (50) each comprise a thin nickel-based layer having identical thicknesses or almost identical. 4. Substrate (10) according to any one of the preceding claims, characterized in that the thin nickel-based layer of the subblock coating (30) and / or the thin nickel-based layer of the coating. over-blocking (50) is directly in contact with the functional layer (40). 5. Substrate (10) according to any one of the preceding claims, characterized in that your functional layer (40) has been deposited at a high vacuum pressure, equal to or greater than 2.103 Torr, and preferably between 2.5.10 3 Torr and 5.103 Torr. 6. Substrate (10) according to claim 5, characterized in that said high vacuum pressure is between 3.10-3 Torr and 4.5.10-3 Torr and is preferably of the order of 3.5.10-3 Torr. 7. Substrate (10) according to any one of the preceding claims, characterized in that at least one thin nickel-based layer, and in particular that of the over-blocking coating (50), comprises chromium, preferably in atomic amounts of 80% Ni and 20% Cr. 8. Substrate (10) according to the preceding claim, characterized in that at least one thin nickel-based layer, and in particular that of the over-blocking coating, consists of an NiCr alloy present in metallic form if the substrate provided with the stack of thin layers has not undergone heat treatment of bending and / or quenching after the deposition of the stack, said alloy being at least partially oxidized if the substrate provided with the stack of thin layers has undergone at least one heat treatment of bending and / or quenching after deposition of the stack. 9. Substrate (10) according to any one of claims 1 to 6, characterized in that at least one thin nickel-based layer, and in particular that of the over-blocking coating (50), comprises titanium, preferably in atomic amounts of 80% Ni and 20% Ti. 10. Substrate (10) according to the preceding claim, characterized in that at least one thin nickel-based layer, and in particular that of the over-blocking coating, consists of an NiTi alloy present under metallic form if the substrate provided with the stack of thin layers has not undergone heat treatment of bending and / or quenching after the deposition of the stack, said alloy being at least partially oxidized if the substrate provided with the stack of thin layers has undergone at least one heat treatment of bending and / or quenching after the deposition of the stack. 11. Substrate (10) according to any one of the preceding claims, characterized in that it comprises a last layer, a protective layer (70) ta farthest from the substrate, based on oxide, preferably deposited under stoichiometric , and in particular based on TiOX. 12. Glazing incorporating at least one substrate (10) according to any one of the preceding claims, optionally associated with at least one other substrate. 13. Glazing according to the preceding claim mounted in monolithic or in multiple glazing of the double-glazing or laminated glazing type, characterized in that at least the substrate carrying the stack is curved and / or tempered. 14. A method of manufacturing a glass substrate (10) provided on a main face with a stack of thin layers, in particular the substrate according to any one of claims 1 to 10, the stack comprising a functional layer (40). metallic with reflective properties in the infrared and / or in solar radiation, in particular based on silver or a metallic alloy containing silver, and two anti-reflective coatings (20, 60), said coatings each comprising at least a dielectric layer (24, 64) based on silicon nitride, said functional layer (40) being disposed between the two anti-reflective coatings (20, 60), the functional layer (40) being deposited directly on an underblocking coating (30) disposed between the functional layer (40) and the underlying antireflection coating (20) and the functional layer (40) - 23 - being deposited directly under an over-blocking coating (50) disposed between the functional layer ( 40) and coating overlying antireflection (60), characterized in that the stack of thin layers is deposited on the substrate by a vacuum technique of the sputtering type optionally assisted by a magnetic field and in that for said substrate to be bent and / or hardenable after the deposition of the stack of thin layers, a thin nickel-based layer is deposited in the underblocking coating (30) and / or in the overblocking coating (50) at high vacuum pressure , equal to or greater than 2.10 "3 Torr, and preferably between 2, 5.10-3 Torr and 5.103 Torr. 15. Method according to the preceding claim, characterized in that the functional layer (40) is deposited at a high vacuum pressure, equal to or greater than 2.10-3 Torr, and preferably between 2.5.10-3 Torr and 5.10- 3 Torr. 16. Method according to the preceding claim, characterized in that the functional layer (40) is deposited at the same high vacuum pressure as the underblocking coating (30) and the overblocking coating (50). 17. Method according to any one of claims 14 to 16, characterized in that said high vacuum pressure is between 3.10-3 20 Torr and 4.5.103 Torr and is preferably of the order of 3.5.10-3. Torr. 18. A method according to any one of claims 17 or 18, characterized in that the or each thin nickel-based layer has a thickness e such as 1.5 nm e 5 nm. 19. Use of the substrate according to any one of claims 1 to 11, for producing a substrate which is bendable and / or hardenable after the deposition of the stack of thin layers and which preferably exhibits a variation on heat treatment. of light transmission in the visible ATL 5 and / or a calorimetric variation in reflection AE 6.