JP5662314B2 - Protective coating and method - Google Patents

Description

Cross-reference of related applications

  This application claims the priority of US Provisional Patent Application No. 61/190488, filed Aug. 29, 2008, under the title of “INTERNAL PASSIVATION OF GLASS DELIVERY SYSTEMS”. The contents are trusted by reference in their entirety and incorporated herein.

  The present disclosure relates to metallic protective coatings and methods. In particular, the present invention relates to oxide protective coatings for noble metals and methods for forming those coatings. The present invention is useful, for example, for passivation and protection of platinum components in glass supply systems at high operating temperatures in an oxidizing atmosphere.

  Development of methods and compositions aimed at reducing component damage that can occur during processes performed in harsh thermal environments, for example, where high temperatures can cause or accelerate the degradation of critical process components However, it has attracted attention in recent years. Damage to these process components can be expensive and subsequently cause other potentially disadvantageous process problems.

  As a typical process performed in a severe thermal environment, there is a glass manufacturing method such as an overflow downdraw fusion method described in Patent Document 1 (Dockerty) and Patent Document 2 (Dockerty). Many glass manufacturing equipment is made of durable inert materials such as precious metals, yet high process operating temperatures can still create harsh environments where components are exposed to oxidation and thermal stresses. For example, glass for electronic displays can be processed using precious metal supply, retention, and forming equipment. The temperature used in such glass processing techniques is high enough to oxidize the bare surface of the noble metal portion, producing a volatile noble metal oxide that can be reduced in sequence to form metal particles. The reduced metal particles may form inclusions of contaminants in the glass produced by such a method. Especially in semiconductor applications where very high glass quality (smoothness, homogeneity, etc.) is required, the resistance to such contaminants may be low.

U.S. Pat. No. 3,338,696 US Pat. No. 3,682,609

  There is a need to address the aforementioned problems and other drawbacks associated with conventional glass manufacturing methods and other methods. The compositions and methods of the present disclosure meet these and other needs.

  Several aspects of the invention are disclosed herein. It should be understood that aspects may or may not overlap each other. Thus, some aspects may be included within the scope of another aspect, and vice versa.

  Each aspect is illustrated by one or more embodiments, which can similarly include one or more specific embodiments. It should be understood that the embodiments may or may not overlap each other. Thus, a portion of one embodiment, or a particular embodiment thereof, may or may not be included within the scope of another embodiment, or those particular embodiments, The reverse is also true.

The first aspect of the present invention is:
(I) a first layer having a first surface comprising a first metal;
(Ii) a second layer comprising an oxide of a second metal that directly bonds to the first surface of the first layer and covering at least a portion of the first surface of the first layer; ,
A device with: where:
(A) the contact surface between the first layer and the second layer is substantially dense and has an irregular topography;
(B) When the second metal is deposited on the first surface of the first metal at a high temperature, the second metal has an ability to form an alloy with the first metal.
Relates to the device.

  In certain embodiments of the first aspect of the invention, (C) a second metal and a first metal having a thickness substantially equal to the second layer supported by the inert substrate; When one of the main surfaces of a metal film made of a mixture of the above is exposed to air at a temperature ranging from 1000 ° C. to the melting temperature of the first metal for a sufficient time, the metal film is completely oxidized. Thus, a high-density oxide film can be formed on the inert substrate.

  In certain embodiments of the first aspect of the invention, the first metal comprises a noble metal and the second metal comprises at least one of Al, Zr, and Si.

In certain embodiments of the first aspect of the invention, the first layer comprises Pt and the second layer consists essentially of Al ₂ O ₃ .

  In certain embodiments of the first aspect of the invention, the interface between the first layer and the second layer has a convolution index of at least 1.50, At least 1.55 in form, at least 1.60 in certain embodiments, at least 1.65 in certain embodiments, and at least 1.70 in certain embodiments In certain embodiments, it is at least 1.75.

  In certain embodiments of the first aspect of the invention, the second layer has a thickness of about 5 μm to about 80 μm, and in certain embodiments is about 10 μm to about 70 μm, and In certain other embodiments from about 20 μm to about 60 μm, in certain specific embodiments from about 20 μm to about 50 μm, in certain other embodiments from about 25 μm to about 45 μm, In other embodiments, it is about 30 μm to about 40 μm.

  In certain embodiments of the first aspect of the invention, the apparatus is a component of a molten glass supply system.

  In certain embodiments of the first aspect of the invention, the apparatus is a microtube of a glass melting system.

  In certain embodiments of the first aspect of the invention, the apparatus is a stirred chamber in which the molten glass is subjected to shear stress.

  In certain embodiments of the first aspect of the invention, the apparatus is a coating of a stirring chamber.

  In certain embodiments of the first aspect of the invention, the device is a flange, such as an electrical flange, for transmitting power.

In certain embodiments of the first aspect of the invention, the second layer covers essentially all areas of the exposed surface of the device that would otherwise be exposed to an O ₂ containing atmosphere. In certain more specific embodiments, the outer surface of the device is coated with a second layer.

In a first certain embodiments of aspects of the present invention, the second layer, for the first oxide of a metal such as PtO _2, which is substantially impermeable.

In certain embodiments of the first aspect of the invention, the second layer is substantially O ₂ impermeable.

  In certain embodiments of the first aspect of the invention, the second layer is substantially free of the second metal in the metallic state.

  In certain embodiments of the first aspect of the present invention, the second layer and the first layer form interlocking characteristics at their contact surfaces.

A second aspect of the present invention relates to a method for protecting a first surface of a first layer comprising a first metal in a device from oxidation at elevated temperatures when exposed to an oxidizing atmosphere,
(A) providing a precursor layer containing a second metal on at least a portion of the first surface of the first metal, wherein the second metal provides the precursor layer; Under the ability to form an alloy with the first metal,
(B) forming a second layer containing an oxide of the second metal by exposing the precursor layer to an oxidizing atmosphere at a high temperature;
It has each process.

  In certain embodiments of the second aspect of the invention, the first metal comprises Pt.

  In certain embodiments of the second aspect of the present invention, the first metal comprises Pt and the second metal comprises at least one of Al, Si and Zr.

  In certain embodiments of the second aspect of the invention, in step (a), the precursor layer has a thickness of about 7 μm to about 120 μm, and in certain embodiments about 10 μm to about 120 μm. 100 μm, in certain other embodiments from about 15 μm to about 80 μm, in certain other embodiments from about 20 μm to about 60 μm, and in certain specific embodiments from about 20 μm to about 50 μm. In certain other embodiments from about 25 μm to about 45 μm, and in certain other embodiments from about 30 μm to about 40 μm.

  In certain embodiments of the second aspect of the present invention, at the end of step (b), the contact surface of the first layer and the second layer is substantially dense, and , Have irregular topography.

  In certain embodiments of the second aspect of the present invention, in step (b), the second layer is a convolution wherein the contact surface between the first layer and the second layer is at least 1.50. Formed with an index, in certain embodiments at least 1.55, in certain embodiments at least 1.60, in certain embodiments at least 1.65, In certain embodiments it is at least 1.70 and in certain embodiments it is at least 1.75.

  In certain embodiments of the second aspect of the present invention, step (a) includes at least one of CVD, pack cementation, slurry coating, sputtering, electroplating, and the like.

  In certain embodiments of the second aspect of the present invention, step (b) is performed in a preheating stage.

  In certain embodiments of the second aspect of the invention, step (b) is performed in-situ when the device is incorporated into an operating system. In a more specific embodiment, the operating system is a glass melting and / or feeding system.

  In certain embodiments of the second aspect of the invention, at the end of step (b), the second layer has a thickness of about 5 μm to about 80 μm, and in certain embodiments about 10 μm to about 70 μm, in certain other embodiments from about 20 μm to about 60 μm, in certain specific embodiments from about 20 μm to about 50 μm, and in certain other embodiments, about 25 μm. To about 45 μm, and in certain other embodiments from about 30 μm to about 40 μm. In certain embodiments of the second aspect of the present invention, in step (a), the provided precursor layer consists essentially of a mixture of a first metal and a second metal.

  In certain embodiments of the second aspect of the present invention, in step (b), the elevated temperature is in the range of 1000 ° C. to the melting temperature of the first metal.

  In certain embodiments of the second aspect of the invention, at the end of step (b), the elevated temperature ranges from 1000 ° C. to the melting temperature of the precursor layer.

  In certain embodiments of the second aspect of the present invention, in step (b), the second metal in the precursor layer is completely converted to their oxides.

  In certain embodiments of the second aspect of the present invention, in step (b), the precursor layer is formed of the second metal without the molten second metal flowing significantly over the first metal. It is heated to a high temperature at a certain rate of temperature rise so that oxidation occurs.

  The third aspect of the present invention relates to a method for producing sheet glass by using an apparatus according to the present invention as outlined above and described in further detail below.

  In certain embodiments of the third aspect of the invention, the apparatus comprises a stirring chamber, a finer, a flange, or a connecting tube.

One or more embodiments of one or more aspects of the present invention have one or more of the following advantages. First , a dense heat-resistant protective coating can be formed on the outer surface of the metal structure to protect it from harmful oxidation. Second, a coating can be formed on a surface having a complex shape. Third, the coating can be formed at a relatively low cost. Fourth, the coating can have a high interfacial bond strength between the first metal layer and the second oxide protective layer.

  Additional embodiments of the present disclosure are set forth in part in the detailed description and appended claims, and in part are derived from the detailed description, or can be understood by practice of the disclosure. Like. It should be understood that the foregoing summary and the following detailed description are exemplary and exemplary only and are not restrictive of the invention disclosed and / or recited in the claims. is there.

 The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate certain examples of the present disclosure, and together with the description, serve to illustrate, without limitation, the principles of the present disclosure. To do. Similar reference numbers refer to the same elements throughout the figures.

The scanning electron microscope image of the cross section 100 of the Pt-Rh metal piece provided with the precursor layer containing metal Al. Scanning electron microscope image of a cross section of one Pt—Rh metal piece with a fully oxidized Al ₂ O ₃ layer. Scanning electron microscope image of Pt-Rh substrate surface after removal of the layer of Al ₂ O ₃ previously formed on the substrate. FIG. 6 is a method for collecting and analyzing images to acquire information on a Pt—Rh substrate processed in accordance with certain embodiments of the present invention. FIG. 6 is a method for collecting and analyzing images to acquire information on a Pt—Rh substrate processed in accordance with certain embodiments of the present invention.

  The following description of the present disclosure is provided as a possible teaching of the present invention in its best known embodiment. To accomplish this goal, those skilled in the art will recognize and understand that many changes can be made to the various embodiments of the disclosure described herein, while obtaining the beneficial results of the present disclosure. Will. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the features of the present disclosure without utilizing other features. Accordingly, those skilled in the art will appreciate that many modifications and adaptations to the present disclosure are possible and that even certain circumstances are desirable and are part of the present disclosure. Accordingly, the following description is provided as illustrative of the principles of the present disclosure and not in limitation thereof.

In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings:
Ranges are expressed herein as from “about” one particular value and / or to “about” another particular value. When ranges are expressed in this way, another example includes from one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation using the antecedent “about,” it will be understood that that particular value forms another embodiment. It will be further understood that the end point of each range is important both when it is related to another end point and independent of the other end point.

  For example, if a particular metal component is disclosed, discussed, and discussed many changes that can be made to that metal component, unless otherwise specified, individual and all combinations of that metal component and possible changes and Permutations are clearly intended. Accordingly, the types A, B, and C of the metal component are disclosed, and at the same time, the types D, E, and F of the metal component are disclosed. Each of which is individually and collectively intended meaning combinations, A-E, A-F, B-D, B-E, B-, even though each is not individually listed. F, CD, CE, and C-F are considered disclosed. Similarly, any subset or combination of these is also disclosed. Thus, for example, the subgroups of AE, BF, and CE are considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the disclosed compositions. Thus, where there are various additional steps that can be performed, each of these additional steps can be performed in any particular embodiment or combination of embodiments of the disclosed methods. I want you to understand what I can do.

  As used herein, “% by weight” or “percent by weight” or “percent by weight” refers to ingredients relative to the total weight of a composition containing the ingredients expressed as a percentage, unless expressly stated to the contrary. It means the ratio of weight.

As used herein, the term “convolution index” describes the topography of the interface between a first layer of material and a second layer of material. The convolution index (CI) is defined as follows:
CI = Lc / Ls
Here, Lc connects two points on the contact surface, obtained by cutting the contact surface at a plane substantially perpendicular to the central plane of the first layer of material, measured at a resolution scale of about 1 μm. Ls is the length of the straight line connecting the same two points. The protocol for measuring the convolution index will be described in detail below. Thus, a perfectly flat contact surface has CI = 1, and as the CI value increases, the topography of the contact surface becomes more irregular. In this application, it should be understood that Lc is measured on a resolution scale of about 1 μm, since the resolution of the measurement can affect the final CI value. “Random topography” means that the contact surface has a convolution index of at least 1.48. As the CI value increases, the contact area between the first layer and the second layer increases, and therefore the adhesion between the first layer and the second layer becomes stronger.

  In the present specification, a substantially high-density contact surface means a contact surface that substantially does not include voids when observed at a resolution scale of 1 μm.

I. As briefly described above, the device of the present invention is
(I) a first layer comprising a first metal having a first surface;
(Ii) a second layer comprising an oxide of a second metal that directly bonds to the first surface of the first layer and covering at least a portion of the first surface of the first layer; ,
Where:
(A) the contact surface between the first layer and the second layer is substantially dense and has an irregular topography;
(B) When the second metal is deposited on the first surface of the first metal at a high temperature, the second metal has an ability to form an alloy with the first metal. In certain embodiments, the first metal and the second metal further satisfy the following condition:
(C) one of the main surfaces of the metal film containing the second metal and the first metal having a thickness substantially equal to the second layer supported by the inert substrate from 1000 ° C. When exposed to air at high temperatures between the melting points of one metal, the second metal in the metal film is substantially completely oxidized to form a dense oxide film on the inert substrate. can do.

  The device of the present invention can be a stand-alone device or part of a larger system. Thus, for example, the device can be a container for containing a fluid or reaction medium. In addition to the two layers described above, the device may include additional layers adjacent to the first or second layer. For example, the device can include a third layer adjacent to the second layer and covering at least a portion of the second layer. In another example, the device may further include a fourth layer covering at least the second surface of the first layer adjacent to the second surface of the first layer. The device can further include other functional components apart from the first and second layers.

  In one embodiment, the apparatus of the present invention comprises a conduit for carrying a hot fluid, such as a glass melt, which is coated with a second layer of a second metal oxide. A wall made of a first metal. Such a conduit can be, for example, a finer, a glass melting and connecting tube between different stations of the feeding system. In another embodiment, the apparatus of the present invention comprises a vessel in which a hot fluid such as a glass melt is agitated and homogenized.

In embodiments in which a device such as the glass fluid handling device as described above is adapted to operate at high temperatures, the first metal advantageously comprises a noble metal. Precious metals are known for high temperature resistance to oxidation and erosion by materials such as glass fluids. Thus, the opposite side of the first surface of the first layer is designed to allow the device to operate, and the first layer of the device of the present invention may be capable of contacting a hot fluid. For example, if the device is equipped with a finer for handling glass melt, the wall of the microtube can be composed of Pt or Pt-Rh alloy, and its inner surface is in its normal operation. In between, a glass melt can be included and the outer surface is coated with an Al ₂ O ₃ coating. Thus, the first layer can be composed of a single metal or a combination of multiple metals.

However, noble metals are usually very expensive and therefore the first layer is designed to be as thin as possible. In addition, even noble metals such as Pt and Rh are known to be susceptible to oxidation, especially at temperatures above 500 ° C., by the following mechanism:
Pt (solid) + O ₂ (gas) ← → PtO ₂ (gas) (1)
Rh (solid) + O ₂ (gas) ← → RhO ₂ (gas) (2)
Oxidation results in metal loss, metal wall thinning, and Pt inclusions in the glass melt due to subsequent dissociation of PtO ₂ gas and condensation of particulate Pt on relatively cool surfaces. All of these are highly undesirable. The second layer of oxide of the second metal in the device of the present invention serves to suppress the diffusion of O ₂ from the atmosphere to which the device is exposed, thereby increasing the glass, for example above 1500 ° C. The reaction (1) can be suppressed even at a high temperature such as the normal operating temperature of the microtubule.

The second metal can form an alloy with the first metal in the metallic state when both metals are in contact at high temperatures, such as above 500 ° C., when in the metallic state. The alloying capability allows the formation of complex and intricate contact surfaces between the first and second layers of the device of the present invention. It should be noted that the alloy can be a mixture or combination of two metals in various molar percentages, as described above. Indeed, the first metal and the second metal can form various types of alloys under predetermined alloying conditions. For example, it may first metal Pt is at high temperature, such as two metals are contactable 800 ° C. together with Al will second metal, in various composition represented by Pt _x Al _y An alloy can be formed. Furthermore, as described above, the first layer may include a combination of a plurality of metals (eg, a Pt—Rh alloy). In such cases, in addition to the first metal (eg, Pt), other metals contained in the first layer may also have the ability to form an alloy with the second metal at high temperatures. The present invention is not required to function as such.

  A second layer comprising an oxide of the second metal covers at least a portion of the first surface of the first layer and is, for example, high temperature, erodible to the first surface of the first layer. Normal operation of the first layer, such as when exposed to an additional fluid that does not meet the compatibility requirements of the fluid or the first surface of the first layer The coated portion of the first surface of the first layer is at least partially isolated from the environment that would have been exposed to an atmosphere that is reactive under conditions.

In embodiments where the apparatus of the present invention is designed to function at high temperatures, for example, exceeding 1000 ° C., it is desirable that the oxide of the second layer be a heat resistant material. For example, a glass melting and feeding system microtubule can operate at a high temperature of 1500 ° C. Pt and Pt—Rh alloys are suitable candidate materials for the walls of microtubules. Suitable oxides for the second layer covering the outer surface of the microtubule wall include, for example, Al ₂ O ₃ , ZrO ₂ , MgO, TiO ₂ , SiO _{2 and the} like, and mixtures and combinations thereof. It is possible. In certain embodiments, Al ₂ O ₃ and ZrO ₂ are particularly desirable. In the present application, for convenience of explanation, Si is included in the planned second metal group.

In order to obtain a strong adhesion between the first layer and the second layer and to prevent delamination between the first layer and the second layer after a few operating cycles, Desirably, the one or more metals and the second layer oxide have substantially similar coefficients of thermal expansion (CTE). Pt, Pt—Rh and Al ₂ O ₃ have similar CTEs under normal glass manufacturing conditions.

In certain embodiments, it is highly desirable that the second layer be substantially dense, ie essentially free of voids and cracks greater than 1 μm. In certain embodiments, it is desirable for the second layer to be essentially free of voids and cracks greater than 500 nm. In certain other embodiments, it is desirable for the second layer to be essentially free of voids and cracks greater than 300 nm. In certain embodiments, it is desirable for the second layer to be essentially free of voids and cracks greater than 100 nm. As the second layer becomes denser, the diffusion rate of fluid (eg, O ₂ or other gas) passing through the layer becomes slower and more effectively separates into the first surface of the first layer. And bring protection.

In order to protect the first layer containing Pt from the O ₂ containing atmosphere, it is highly desirable that the second layer be essentially free of voids and cracks that would leak large amounts of PtO ₂ . As mentioned above, Pt and O ₂ undergo the following reaction (1):
Pt (solid) + O ₂ (gas) ← → PtO ₂ (gas) (1)
PtO ₂ has a much larger molecular size than O ₂ , so the volume resistance diffuses through the more spatial second layer. Thus, if the voids and cracks in the second layer allow for the rapid diffusion of O ₂ , but reaction P1O ₂ diffusion is substantially inhibited, reaction (1) will quickly reach equilibrium and thus further It will prevent oxidation and loss of Pt. Thus, in certain embodiments of the invention, the second layer is very dense and substantially inhibits gas phase diffusion through the first metal oxide under operating conditions. It is highly desirable to do. Thus, if the first layer includes Pt, the second layer (such as an Al ₂ O ₃ layer) will allow voids and cracks that will allow free diffusion of PtO ₂ under normal operating conditions of the device. It is desirable not to contain essentially. In certain embodiments, it is further desirable that the second layer be essentially free of voids and cracks so as to suppress O ₂ diffusion under normal operating conditions.

  In certain embodiments, the second layer is essentially free of the second metal in the metallic state, i.e., the second metal in the second layer is substantially completely oxidized. It is desirable. The fully oxidized second layer is stable under the normal operating conditions of the device. Nevertheless, it is not excluded that a portion of the second metal in the second layer is in the metallic state, which may be desirable in certain embodiments. It is not excluded that a part of the second metal in the metal state forms a mixture such as a metal under the second layer at the end of step (b). In those embodiments, if the second layer is designed to be exposed to a fluid, it is highly desirable that at least the surface of the second layer exposed to the fluid be fully oxidized. The second metal in the remaining metal state can replenish a portion of the second layer consumed during operation, particularly in the region adjacent to the first layer, and thus in certain implementations. This is desirable. However, in other embodiments, due to the ability of the second metal in the metal state to alloy with the first metal, during operation of the device, the second metal is bulked in the first layer. It can diffuse deeply into and cause weakening of the first layer and is therefore undesirable.

  As briefly described above, the contact surfaces of the first layer and the second layer in the device of the present invention are substantially complicated. Therefore, when the contact surface is cut by a surface substantially perpendicular to the median surface of the first layer to obtain a cross-section, the uneven curve on the 1 μm resolution scale can be observed with, for example, an electron microscope. In certain embodiments, the high convolution index of the contact surface between the first layer and the second layer is a prominent feature that distinguishes the present invention from that of metal coated in the prior art. . The contact surfaces of the first and second layers in the apparatus of the present invention have a convolution index of at least 1.48, in certain embodiments at least 1.50, and in certain embodiments. At least 1.60, in certain other embodiments at least 1.70, and in certain embodiments at least 1.80.

  Of course, increasing the thickness of the second layer can provide greater resistance to diffusion of fluid through it. However, increasing the thickness of the coating is more expensive to form and may be unnecessary in certain embodiments. The thickness of the second layer is defined as the average shortest distance from the surface of the second layer remote from the first layer to the first surface of the first layer. Thus, in certain embodiments, the second layer has a thickness of up to 80 μm, in certain other embodiments up to 60 μm, and in certain other embodiments. Up to 50 μm, in certain other embodiments up to 40 μm, and in certain specific embodiments up to 30 μm. To obtain a suppression threshold for diffusion, the thickness of the second layer is desirably at least 5 μm in certain embodiments, and at least 10 μm in certain embodiments, It is at least 20 μm in form, and in certain embodiments at least 30 μm.

The intricate contact surfaces of the first layer and the second layer can include certain interlocking properties, i.e., certain portions of the first layer protrude into the second layer, and / or A certain part of the second layer protrudes into the first layer. Such interlock characteristics are particularly desirable for strong adhesion between two layers. The 1 μm scale interlocking properties are not easy to form by using conventional coating methods such as direct chemical vapor deposition of the second layer oxide. Although it is particularly difficult to form through the use of conventional coating methods, the interlock property essentially free of voids that can be obtained according to the present invention can be provided simultaneously with high interfacial adhesion strength. Highly desirable due to the low diffusivity of fluids (such as O ₂ ). In certain embodiments, the first metal overhang directly connects to the bulk with the first layer, and / or the second layer oxide overhang is the second It is desirable to connect directly to the oxide bulk of the layer. Such a continuous structure of the first layer and the second layer enhances the bond strength between the first layer and the second layer. Nevertheless, in certain embodiments, certain bulk of the first metal in the bulk of the second metal oxide in the second layer that is not directly bonded to the bulk of the first metal. It does not exclude the presence of discrete particles. In certain embodiments, a particular discrete island of oxide of the second metal is formed under the second layer and trapped within the bulk of the first metal. It is not excluded.

  A high convolution index at the contact surface of the first and second layers provides a large contact area between the two layers, thus greatly enhancing the adhesion between the two layers. The interlock property, when present, further improves bond formation.

  Due to the presence of the protective coating of the second layer in the device of the present invention, the oxidation and loss of the first layer can be reduced. In embodiments where the first metal includes a noble metal such as Pt, these protections result in significant equipment life and capital savings.

On the other hand, the Pt inclusions in the glass manufacturing process that can penetrate into the glass melt and form undesirable defects due to the dissociation of PtO _{2 in} the low temperature region and the condensation of Pt metal particles, It is known that it can occur in glass. Therefore, the apparatus of this invention can also improve glass quality, when used appropriately in a glass manufacturing system.

  FIG. 1 shows a scanning electron microscope image of a cross-section 100 of one Pt—Rh metal piece having a precursor layer containing metallic Al. The structure and composition of this cross section in FIG. 1 will be described in more detail below.

FIG. 2 shows a scanning electron microscope image of a cross section of one Pt—Rh metal piece with a fully oxidized Al ₂ O ₃ layer prepared by using the metallization process of the present invention described below. ing.

FIG. 3 is a scanning electron microscope image of the surface of the Pt—Rh substrate after removing the Al ₂ O ₃ layer previously formed on the substrate. This image reveals the intricate features of the first surface of the Pt—Rh layer.

II. Device Manufacturing Method A second aspect of the present invention is directed to a method for protecting a first surface of a first layer comprising a first metal in a device at an elevated temperature when exposed to an oxidizing atmosphere,
(A) providing a precursor layer comprising a second metal in a metallic state on at least a portion of the first surface of the first metal, wherein the second metal is the precursor; Having the ability to form an alloy with the first metal under the conditions in which a body layer is provided;
(B) forming a second layer containing an oxide of the second metal by exposing the precursor layer to an oxidizing atmosphere at a high temperature;
It has each process.

Step (a) may include a step of performing a sputtering, chemical vapor deposition, slurry deposition, or the like to form a precursor layer of the second metal in the metal state. During step (a), the second metal enters the first layer, the first metal enters the precursor layer, and simultaneously the first metal gradient and the second metal gradient are applied to the contact surface. Form. In certain embodiments, it is desirable that at least the top portion of the precursor layer is essentially free of the second metal, and it is desirable that the second metal does not penetrate the entire thickness of the first layer. In certain other embodiments, the precursor layer comprises a mixture of a first metal and a second metal throughout its thickness. For example, a precursor layer consisting essentially of Pt _{x A y} can be formed when Al is deposited on the surface of a Pt substrate.

When the first metal is Pt or Pt—Rh and the second metal is Al, the Al layer can be deposited by sputtering, conventional chemical vapor deposition, slurry deposition, or the like. Since Pt and Al are known to form alloys represented by Pt _x Al _y , the contact surface is a Pt—Al mixture with various Pt / Al molar ratios.

  With respect to the first metal, the first layer, and the second metal, it may be as described above for the device of the present invention. Thus, the first metal can be a noble metal such as Pt or a Pt—Rh alloy, and the second metal can be Al, Zr, Ti, Si, Mg, and mixtures and combinations thereof.

  The thickness of the precursor layer is defined as the average shortest distance from the surface of the precursor layer away from the first layer to the first surface of the first layer where the concentration of the second metal is negligible. Thus, the thickness of the precursor layer is determined in part by the desired thickness of the final second layer of oxide of the second layer. The thickness of the precursor layer is preferably 120 μm or less in certain embodiments, particularly when the first metal includes Pt and the second metal includes Al, Is 100 μm or less in other embodiments, 80 μm or less in other embodiments, 60 μm or less in other embodiments, 50 μm or less in other embodiments, and in other embodiments, 40 μm or less. Nevertheless, in order to form a sufficiently thick second metal oxide first layer, the thickness of the precursor layer, in certain embodiments, is at least 20 μm. Is desirable. Thus, in step (a), the precursor layer has a thickness of about 20 μm to about 60 μm in certain embodiments, and 20 μm to about 50 μm in certain other embodiments, In other embodiments, from about 25 μm to about 45 μm, and in certain other embodiments, from about 30 μm to about 40 μm.

  In step (a), the precursor layer can be formed using various techniques, such as conventional chemical vapor deposition, plasma enhanced chemical vapor deposition, slurry deposition, sputtering, electroplating, and the like. Different precursor layer thicknesses can be achieved using these different techniques, but certain methods may be most suitable for making metal coatings with a given thickness. It will be understood that there is. Thus, if the first metal layer of the second layer is too thick to fully oxidize to the second layer of the second metal, the precursor layer with the second metal deposited can be converted to, for example, chemical mechanical It would be desirable to reduce the thickness of the second metal layer to a desired range by subjecting it to a thinning step such as a polishing step. A particularly desirable method for forming the Al-containing metal layer directly on the first metal, such as that comprising Pt, is slurry deposition. These methods result in a substantially dense Al—Pt alloy layer having a substantially uniform thickness in the range of 20-60 μm without the need for a thinning step. Can do.

  In a specific embodiment, step (a) may include a post-deposition heat treatment step before step (b). Forming a mixture comprising a first metal and a second metal prior to step (b) is highly desirable for the formation of contact surfaces having a high convolution index in the apparatus of the present invention. Certain thin layer deposition methods are performed at temperatures at which a mixture of first and second metals or intermetallic compounds is formed at a very slow rate. A post-deposition heat treatment in which the contact surface is heated to a temperature higher than the deposition temperature can facilitate the formation of a metal mixture in the precursor layer prior to step (b). For example, a conventional Al CVD method performed at less than 500 ° C. results in a precursor Al layer lacking Pt on a Pt—Rh alloy substrate, and post-deposition heat treatment at about 1000 ° C. is performed with Al and Pt. It has been found to promote the formation of intermetallic compounds.

Regardless of the method used, it is desirable to form an alloy of the first and second metals in step (a). Thus, the contact surface of the first layer and the precursor layer includes a gradient of the first metal and the second metal, and the range is from a region at one end that includes a negligible level of the second metal, It extends to the middle region where the alloy or mixture is present and to the region at the opposite end containing the lowest level of the first metal. Thus, in certain embodiments where the first metal is Pt and the second metal is Al, the contact surface is represented by Pt · Al from the first layer consisting essentially of Pt. Up to the intermediate region where it is possible to extend to the region consisting essentially of Al. In another embodiment where the first metal is Pt and the second metal is Al, the contact surface may be represented by Pt · Al from the surface of the first layer consisting essentially of Pt. To the possible intermediate region and to the region at the opposite end consisting essentially of Al ₂ Pt. The latter embodiment, in which the precursor layer includes a mixture of Pt and Al throughout their thickness, can be particularly advantageous because the melting temperature of Al ₂ Pt is significantly higher compared to Al.

In step (b) of the method of the present invention, the precursor layer is exposed to an O ₂ containing atmosphere at an elevated temperature. For example, these oxidations in the step (b) can be performed in air at a temperature higher than 500 ° C., such as a temperature higher than 800 ° C., and examples include a temperature higher than 1500 ° C. The precursor layer is oxidized to the second layer under such conditions. As an example, an embodiment is described in which the first metal is made of Pt and the second metal is made of Al. Aluminum in the surface region of the Al-containing precursor layer is first oxidized to Al ₂ O ₃ . O ₂ then diffuses through the Al ₂ O ₃ layer and oxidizes the underlying metal Al.

In embodiments where the first metal is Pt and the second metal is Al, the second metal is higher than the first metal containing O ₂ at high temperatures when in the metallic state. It is desirable to have reactivity. Under such circumstances, in step (b), when O ₂ diffuses through the oxide layer formed on the second metal and the first metal atom reaches the intermediate region of the contact surface. In addition, the first metal maintains the reduced metal state due to the reduction effect of the second metal. Therefore, in the step (b), the second metal is preferentially oxidized. While not intending to be bound by any particular theory, the second metal oxide tends to agglomerate in the precursor layer with the upper oxide layer, and the first metal in the metallic state is Tend to agglomerate with the bulk of one layer, so that eventually a dense, substantially void-free second layer is deposited on the substantially continuous first surface of the first layer. It is thought that it forms adjacent to. Further, in the step (b), the aggregation of the first metal and the oxide of the second metal in the precursor layer occur substantially randomly, and as a result, at the end of the step (b), the first It is believed to produce a rugged irregular topography of the contact surface between the first layer and the second layer. In certain embodiments, an interlock characteristic on the μm scale is formed as a result. As described above with respect to the device of the present invention, such bumpy contact surfaces and interlocking characteristics contribute to the strong adhesion of the second layer to the first layer.

Of course, the thicker the precursor layer, the thicker the Al ₂ O ₃ layer that would be formed before all the metal Al was oxidized, and at a given O ₂ partial pressure and O ₂ temperature, thick Al ₂ O 3. It becomes more difficult and time consuming to diffuse through the _three layers and reach the remaining Al metal underneath. Therefore, the desired thickness is in the range of the precursor layer described above.

  It is highly desirable in certain embodiments that the second metal be substantially fully oxidized to a stable oxide under oxidizing conditions. Such a complete oxidation results in a stable second layer that is not further oxidized during normal operation of the formed device. However, in certain embodiments, it is not excluded that the second layer includes a non-negligible amount of the second metal in the metallic state in addition to the oxide of the second metal. In applications where the structural strength of the first layer is important and the second metal that enters and remains in the first metal layer can unduly compromise the strength of the first layer, in step (b), It is highly desirable that all of the second metal in the precursor layer be oxidized. In embodiments where the structural strength weakening caused by alloying the first metal with the remaining second metal can be tolerated or neglected, the remaining second metal can include normal wear and tear, such as At the end of step (b), a certain amount may be oxidized during the operation of the device in a subsequent step that could possibly repair or maintain the integrity of the second layer, which could be compromised by the process conditions. It would be desirable to be able to keep the second metal in an alloyed state with the first metal.

  As described above with respect to the apparatus of the present invention, in step (b), the contact surface between the first layer and the second layer is substantially dense and has an irregular topography. It is desirable.

  As described above with respect to the apparatus of the present invention, in step (b), the second layer is such that the contact surface between the first layer and the second layer has a convolution index of at least 1.50. And in certain embodiments at least 1.55, in certain embodiments at least 1.60, in certain embodiments at least 1.65, In certain embodiments it is at least 1.70 and in certain embodiments it is at least 1.75.

In certain embodiments, at the end of step (b), the second layer thus formed, including the oxide of the second metal, is O ₂ due to its high density. Diffusion can be effectively suppressed and the first metal can be further oxidized. In certain other embodiments, at the end of step (b), the second layer thus formed may be O ₂ permeable, but nevertheless of the first metal It is substantially impermeable to gaseous oxides. For example, a second metal is Al, if the first metal is Pt, due to the significantly larger molecular size of PtO _2, Al ₂ O ₃ layer, to diffusion of PtO ₂ than O ₂ It acts as a much more conspicuously suppressing layer and can effectively suppress continuous oxidation and Pt metal leakage. Therefore, the oxide of the second metal such as Al ₂ O ₃ serves as a protective layer against the oxidation of the first metal.

In certain embodiments of the method of the present invention, in step (b), the elevated temperature ranges from 1000 ° C. to the melting temperature of the first metal. When the second metal contained in the precursor layer is oxidized to a high density coating on the first layer, O through the oxide layer is desired for complete second metal oxidation. High temperatures have been found desirable to promote the diffusion of ₂ . Nevertheless, it is desirable that the oxidation step does not cause melting of the first layer. In certain other embodiments, where the precursor layer consists essentially of a mixture such as an intermetallic compound of a first metal and a second metal, in step (b), the elevated temperature is from 1000 ° C. A range up to the melting temperature of the mixture in the body layer is desirable. This is because when the precursor layer is heated to a temperature higher than its melting temperature, the material melts and flows to the surface of the first layer, resulting in a continuous and substantially continuous second metal oxide. This is because the process of forming the high-density layer may be impaired.

In certain embodiments, in step (b), the precursor layer is at a rate of temperature increase such that oxidation of the second metal occurs without significant flow of molten metal on the first metal. It is desirable to be heated to a high temperature. In embodiments where the first metal is Pt and the second metal is Al, it has been found that Al tends to penetrate Pt by alloy formation at about 1000 ° C. A very high oxidation temperature of about 1500 ° C. where Al is immediately oxidized to Al ₂ O ₃ without causing substantial penetration into the first metal bulk would be beneficial. However, in order to obtain a robust Al ₂ O ₃ coating, the formation of intermetallic compounds is required. A significant temperature increase in the oxidation process is considered beneficial for the formation of a robust and dense oxide layer.

In certain embodiments of the method of the present invention, step (b) is performed in a preheating stage before the device of the present invention is formed and incorporated into an operating system. For example, in an embodiment where the device is a Pt microtube coated with Al ₂ O ₃ made by the method of the present invention, the microtube is a Pt tube coated with a layer of Al—Pt alloy at elevated temperatures. By subjecting it to an oxidation process, it can be made completely before being attached to the glass manufacturing system.

On the other hand, if the device of the present invention is designed to operate at high temperatures in an O ₂ containing atmosphere, the device can be formed in-situ upon introduction of the operating system. For example, in an embodiment where the device is an Al ₂ O ₃ coated Pt microtubule made with the method of the present invention, it can be made in-situ according to the following steps:
(1) depositing a layer containing Al on the outer surface of the Pt tube;
(2) Attach the tube obtained from step (1) to the glass melting system,
(3) Preheat the glass melting system so that the tube is heated to high temperature in air, whereby the precursor Al-containing layer is oxidized to form a second layer.

III. 3. Manufacturing method of glass The 3rd aspect of this invention is a glass manufacturing method which uses the apparatus of this invention. The glass manufacturing method
(1) The batch material is melted in a melting tank to obtain a glass melt,
(2) supplying the glass melt to a subsequent process through a conduit;
(3) adjusting the glass melt,
(4) forming the glass melt into a desired form;
Each step can be included. One or more apparatuses of the present invention can be employed in all steps (1) to (4). For example, in step (1), one particular component of the glass melting tank can be a noble metal made according to the present invention and coated with an Al ₂ O ₃ and / or ZrO ₂ layer; step (2) In this case, the supply system can be a Pt—Rh tube having an outer surface coated with Al ₂ O ₃ and / or ZrO ₂ ; in step (3), the microtubule or the stirring chamber is a device according to the invention. In step (4), which may include fusion draw, float, or slot draw, or other forming methods, devices such as isopipes in the fusion downdraw process may be partially or wholly Al _2. It can be a device according to the invention comprising Pt coated with O ₃ and / or ZrO ₂ .

 The invention is further illustrated by the following non-limiting examples.

 All Pt-Rh metal pieces tested contained about 20% by weight Rh.

A series of clean Pt—Rh metal strips containing 20 wt% Rh were prepared and then coated with an Al—Pt intermetallic compound according to the method of the present invention using a slurry deposition method or a CVD method. The resulting Pt—Rh metal pieces coated with Al—Pt aluminide were then observed and / or tested. Next, the aluminum-plated Pt—Rh metal piece was oxidized in air at about 1450 ° C. for about 72 hours. Thereafter, the resultant, a Pt-Rh metal pieces coated with Al ₂ O _3, were observed and / or testing.

FIG. 1 shows a scanning electron microscope image of a cross-section 100 of one Pt—Rh metal piece having a precursor layer containing metallic Al. The composition of the precursor layer, the first layer and the contact surface can be determined through any suitable characterization method. A scanning electron microscope (SEM) equipped with an electron probe microanalyzer (EPMA) can be used, for example, to determine the composition at a given location within the precursor layer and / or bulk metal component. Referring to FIG. 1, 103 is a Ni plated layer added to assist in the preparation of the cross section of the sample and is not part of the apparatus; 105, 107, 109, 111a and 111b are precursors The different major phases of the layer, each with different concentrations of components and different physical structures, 113 is a bulk Pt—Rh metal. The compositions determined from EPMA at various locations are listed in Table 1 below.

FIG. 2 is a scanning electron microscope image of a cross-section of a Pt—Rh substrate comprising a fully oxidized Al ₂ O ₃ layer 201 prepared by the aluminization-oxidation method of the present invention. In this figure, 203 is a bulk Pt—Rh metal, and 205 is a layer of mounting material formed to aid in the preparation of the cross-section for imaging.

FIG. 3 is a scanning electron microscope image of the surface of the Pt—Rh substrate after removing the Al ₂ O ₃ layer previously formed on the substrate. This image reveals the intricate nature of the first surface of the Pt—Rh layer.

 A cross-section of each coated metal piece protected by resin was prepared for imaging. An SEC photograph of the prepared cross section was obtained. About 20 of these images were collected and analyzed for each piece of metal. In order to quantify the degree of convolution, the “convolution index” was measured and calculated as follows.

 Backscattered images were collected on a JEOL 6610 SEM operating at 20 kV.

 An image at a low magnification (˜10 × ˜25 ×) was first taken so that the entire metal piece could be seen. About 10 images were obtained from the upper and lower boundaries of the metal piece. After selecting the position, the SEM image was focused and adjusted to ensure that the metal piece was oriented horizontally with respect to the field of view. Backscattered electronic images were taken at 150x with the highest possible pixel resolution.

Images were analyzed using the NIH ImageJ program (http://rsbweb.nih.gov/ij/). As necessary, the brightness and contrast were adjusted to ensure a noticeable difference in brightness between the Pt—Rh region and the Al ₂ O ₃ or ZrO ₂ coating. No other operations were performed on the image. The image was binarized so that the Pt-Rh region appeared as pure black (pixel value 0) and the remaining image was pure white (pixel value 255). Using the “magic wand (automatic selection)” tool, the Pt-Rh region was selected and its perimeter was measured. The horizontal and vertical lengths were subtracted from the perimeter to obtain intricate contact surface lengths.

 In order to maintain data quality and statistical significance, (i) all images were taken at the same magnification: 150 times; (ii) the location where the images were taken was randomly selected; (iii) for each sample Take a significant number of images (~ 20); (iv) take images at the highest resolution so that the convolution of the contact surface is clear; (v) avoid image artifacts due to JPEG compression Therefore, the images were taken in lossless TIFF format; (vi) the images were visually confirmed during image analysis to ensure that the boundaries were recognized correctly and small undulations were not ignored.

FIG. 4 shows the process flow of the image processing to obtain the sample convolution index. In step 4.1, an SEM image of a cross section of the sample including the Pt—Rh region and the oxide region 401 is obtained. In step 4.2, the Pt-Rh region of the image is separated from the entire image and binarized. In Step 4.3, the circumference Lp and the three right sides L1, L2, and L3 of the Pt-Rh region ABCDA are measured. Next, the length of the intricate contact surface Lc is calculated as follows:
Lc = Lp−L1−L2−L3
The convolution index CI is then calculated as follows:
CI = Lc / Ls = (Lp−L1−L2−L3) / L2

For each of the four comparative examples, Pt—Rh metal strips coated with ZrO ₂ obtained from various sources and directly deposited by plasma spraying were evaluated. FIG. 5 shows an image of the contact surface of one typical sample according to the present invention (corresponding to E1, images 5.1A and 5.1B), and four comparative examples (CE1, image 5. Corresponding to 2A and 5.2B; corresponding to CE2, images 5.3A and 5.3B; corresponding to CE3, images 5.4A and 5.4B; and corresponding to CE4, images 5.5A and 5.5B). The left column contains a large image (ie, images 5.1A, 5.2A, 5.3A, 5.4A and 5.5A), and the right column is enclosed by the rectangle shown in the image in the left column. Enlarged images of the selected regions are included (ie, images 5.1B, 5.2B, and 5.2B, corresponding to 5.1A, 5.2A, 5.3A, 5.4A, and 5.5A, respectively). 3B, 5.4B and 5.5B).

The image analysis results are summarized in Table II.

Pt-Rh metal pieces coated with alumina have a more complicated contact surface compared to metal pieces coated with plasma spray zirconia.

  It will be apparent to those skilled in the art that various modifications and substitutions can be made to the present invention without departing from the scope and spirit of the invention. Thus, it is intended that the present invention cover modifications and variations of this invention provided they are within the scope of the appended claims and their equivalents.

Claims (10)

(I) a first layer having a first surface comprising a first metal that is a noble metal;
(Ii) a second layer comprising an oxide of a second metal that directly bonds to the first surface of the first layer and covering at least a portion of the first surface of the first layer; ,
A device comprising:
(A) the contact surface between the first layer and the second layer is substantially intricate, has a high density, and has an irregular topography;
(B) the second metal is at a high temperature, when deposited on the first of the first surface of the metal, that form a first metal alloy,
apparatus. Before Stories second metal, Si, device according to claim 1, characterized in that it comprises at least one of Zr and Al. The first layer comprises Pt;
The apparatus of claim 1 or 2, wherein said second layer is characterized by consisting essentially of Al ₂ O _3. Wherein the second layer, device substantially O ₂ claims 1 to 3 any one of claims, characterized in that the impermeable.   The device according to claim 1, wherein a contact surface between the first layer and the second layer has a convolution index of at least 1.50. The device according to claim 1, wherein the second layer has a thickness of 5 μm to 80 μm. A method of protecting a first surface of a first layer comprising a first metal in a device from oxidation at an elevated temperature when exposed to an oxidizing atmosphere comprising:
(A) providing a precursor layer comprising a second metal on at least a portion of the first surface of the first metal, wherein the second metal is formed under the forming conditions; The first metal is a noble metal,
(B) forming a second layer containing an oxide of the second metal by exposing the precursor layer to an oxidizing atmosphere at a high temperature;
A method comprising each step. The noble metal comprises Pt,
The method of claim 7, wherein the second metal includes at least one of Al, Si, and Zr. In step (a), the method according to claim 7 or 8, wherein said precursor layer has a thickness of 5 [mu] m to 1 20 [mu] m.   8. At the end of step (b), the contact surface between the first layer and the second layer is substantially dense and has an irregular topography. The method of any one of -9.

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