| WO/2001/063006 | COMBINED HEAT INSULATING LAYER SYSTEMS |
| JP08296061 | IMMERSING ROLL IN ALKALINE SALT BATH |
| JP07258819 | THERMAL SPRAY POWDER AND PRODUCTION OF CARBIDE COATING |
LINEMAN, David M (132 Veterans Drive, Painted Post, New York, 14870, US)
GRZESIK, Paul Richard (61 Summit Street, Corning, New York, 14830, US)
LINEMAN, David M (132 Veterans Drive, Painted Post, New York, 14870, US)
CLAIMS
What is claimed is:
1. A process for reducing the oxidation of a precious metal glass delivery system comprising applying with a thermal spray process a sufficient amount of a material comprising a refractory oxide on the exterior surface of and in contact with the precious metal glass delivery system, thereby reducing the oxidation of the precious metal glass delivery system, with the proviso that the process does not include flame sprayed refractory oxide comprising alumina.
2. The process of claim 1, wherein the thermal spray process is a plasma spray.
3. The process of claim 2, wherein the refractory oxide comprises zircon ia.
4. The process of claim 2, wherein the refractory oxide comprises alumina.
5. The process of claim 1 , wherein the thermal spray process is a flame spray and the refractory oxide comprises zircon ia.
6. The process of claim 1 , wherein the thermal spray process is a high velocity oxygen-fuel or a detonation gun.
7. The process of claim 6, wherein the refractory oxide comprises zirconia.
8. The process of claim 6, wherein the refractory oxide comprises alumina.
9. The process of any of claims 3, 5, or 7, wherein the zirconia is fully stabilized zirconia and is stabilized with a Ca compound.
10. The process of any of claims 3, 5, or 7, wherein the zirconia is fully stabilized zirconia and is stabilized with a Mg and/or Y compound.
11. The process of claim 1 , wherein the precious metal comprises platinum.
12. The process of claim 11 , wherein the precious metal further comprises at least one of rhodium, ruthenium, palladium, osmium, rhenium, or iridium.
13. The process of claim 1 , wherein the thermal spray process is a plasma spray, the refractory oxide comprises fully Ca stabilized zirconia, and the precious metal comprises platinum and rhodium.
14. The process of claim 1 , wherein the refractory oxide forms a coated layer having a thickness of from 0.001 inches to 0.060 inches.
15. The process of claim 1, wherein the glass delivery system comprises at least one or more of a pre-melt exit tube, pre-melt finer tube, finer, finer exit, finer to stir chamber connector tube, stir chamber, stirrer, stir chamber cover, windings, stir chamber to bowl connector tube, bowl, downcomer, or inlet.
16. The process of claim 1 , further comprising applying refractory or ceramic castable material to the thermally sprayed refractory oxide.
17. The process of claim 16, wherein the castable material comprises zirconia or alumina.
18. A process for reducing the oxidation of a precious metal glass delivery system comprising applying with a thermal spray process a sufficient amount of a material comprising a refractory oxide comprising MgO, Tiθ2, or Zrθ2 or a mixture or alloy thereof on the exterior surface of and in contact with the precious metal glass delivery system, thereby reducing the oxidation of the precious metal glass delivery system.
19. A process for reducing the oxidation of a precious metal glass delivery system comprising applying with a plasma spray, high velocity oxygen-fuel, or detonation gun process a sufficient amount of a material comprising a refractory oxide on the exterior surface of and in contact with the precious metal glass delivery system, thereby reducing the oxidation of the precious metal glass delivery system.
20. A precious metal glass delivery system comprising at least one component of the precious metal glass delivery system comprising a precious metal, wherein the precious metal is in contact with and is coated with a material comprising a refractory oxide on the exterior surface of the precious metal, wherein the refractory oxide has been applied with the process of claim 1.
21. A precious metal glass delivery system comprising at least one component of the precious metal glass delivery system comprising a precious metal, wherein the precious metal is in contact with and is coated with a material comprising zirconia on the exterior surface of the precious metal.
22. The precious metal glass delivery system of claim 21 , wherein the zirconia has been plasma sprayed or applied with a high velocity oxygen-fuel or a detonation gun onto the metal.
3. The precious metal glass delivery system of any of claims 20-22, further comprising a layer of zirconia or alumina refractory or ceramic castable material in contact with the zirconia. |
THERMALLY SPRAYED REFRACTORY OXIDE COATING FOR PRECIOUS METAL GLASS DELIVERY SYSTEMS
CLAIM FOR PRIORITY
[0001] This application claims priority to U.S. Application No. 11/513,869, filed August 31, 2006, which application is hereby incorporated by this reference in its entirety for all of its teachings.
BACKGROUND
FIELD OF THE INVENTION
[0002] The present invention relates to reduction of oxidation of precious metal delivery systems for the manufacture of glass.
TECHNICAL BACKGROUND
[0003] Glass delivery systems, which melt, fine, or transport molten glass in a glass making process, are highly susceptible to oxidation problems. The glass delivery systems typically comprise a precious metal and that precious metal under the high temperature of the glass manufacturing system in an oxygen containing environment experiences oxidation problems. Typical precious metal delivery systems have a limited life due to precious metal oxidation and sag when the precious metal component's wall thins and weakens and/or develops a localized oxidation spot that causes a glass leak. Such precious metal delivery systems are typically flame sprayed with Rokide ® alumina coating as the standard oxidation protection coating for delivery systems. However, this coating suffers the deficiencies mentioned above.
[0004] There is a need to address the aforementioned problems and other shortcomings associated with the traditional oxidation protection coatings. These needs and other needs are satisfied by the oxidation protection technology of the present invention.
SUMMARY
[0005] The present invention relates to an improved process for reducing the oxidation of a precious metal glass delivery system and an improved precious metal glass delivery system. The present invention addresses at least a portion of the problems described above through the use of a novel precious metal delivery system oxidation protection coating and application process.
[0006] In a first detailed aspect, the present invention provides a process for reducing the oxidation of a precious metal glass delivery system comprising applying with a thermal spray process a sufficient amount of a material comprising a refractory oxide on the exterior surface of and in contact with the precious metal glass delivery system, thereby reducing the oxidation of the precious metal glass delivery system, with the proviso that the process does not include flame sprayed refractory oxide comprising alumina. The process of the invention provides a greater advantage over the flame sprayed Rokide ® alumina coating in that the process of the invention provides an improved density of coating and better bonding. In certain aspects, the improvement is due to a higher temperature and higher velocity of application.
[0007] In a further detailed aspect, the present invention is directed to a process for reducing the oxidation of a precious metal glass delivery system comprising applying with a thermal spray process a sufficient amount of a material comprising a refractory oxide comprising MgO 1 Tiθ2, or Zrθ2 or a mixture or alloy thereof on the exterior surface of and in contact with the precious metal glass delivery system, thereby reducing the oxidation of the precious metal glass delivery system. [0008] In a further detailed aspect, the present invention is directed to a process for reducing the oxidation of a precious metal glass delivery system comprising applying with a plasma spray, high velocity oxygen-fuel, or detonation gun process a sufficient amount of a material comprising a refractory oxide on the exterior surface of and in contact with the precious metal glass delivery system, thereby reducing the oxidation of the precious metal glass delivery system. [0009] In a further detailed aspect, the present invention further provides a precious metal glass delivery system comprising at least one component of the
precious metal glass delivery system comprising a precious metal, wherein the precious metal is in contact with and is coated with a material comprising a refractory oxide on the exterior surface of the precious metal, wherein the refractory oxide has been applied with the process of the invention.
[0010] In another detailed aspect, the present invention provides a precious metal glass delivery system comprising at least one component of the precious metal glass delivery system comprising a precious metal, wherein the precious metal is in contact with and is coated with a material comprising zirconia on the exterior surface of the precious metal.
[0011] In another detailed aspect, the present invention also provides a product formed by the process of the invention.
[0012] Additional aspects and advantages of the invention will be set forth, in part, in the detailed description and any claims which follow, and in part will be derived from the detailed description or can be learned by practice of the invention. The advantages described below will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects described below. Like numbers represent the same elements throughout the figures.
[0014] Figure 1 shows plasma spray coated zirconia with 4 wt. % CaO and uncoated Pt-20Rh (platinum with 20 wt. % rhodium) weight loss behavior over 40 days at 167O 0 C.
[0015] Figures 2A and 2B show an optical micrograph comparing coating surface appearance. Figure 2A is a flame sprayed coating of Rokide ® after 10 days at
167O 0 C showing cracks up to 3 /i 6 -inch long. Figure 2B is plasma sprayed zirconia with 4 wt. % CaO after 40 days at 167O 0 C showing no cracking.
[0016] Figure 3 compares the linear thermal expansion rate of alumina to fully stabilized (4 wt. % CaO) plasma sprayed zirconia as a precious metal glass delivery coating with the precious metal platinum and Pt-20 Rh.
DETAILED DESCRIPTION
[0017] The present invention can be understood more readily by reference to the following detailed description, examples, and claims, and their previous and following description. However, before the present compositions, articles, devices, and methods are disclosed and described, it is to be understood that this invention is not limited to the specific compositions, articles, devices, and methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.
[0018] The following description of the invention is provided as an enabling teaching of the invention in its currently known embodiments. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects of the invention described herein, while still obtaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be obtained by selecting some of the features of the present invention without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not in limitation thereof.
[0019] Disclosed are materials, compounds, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are products of the disclosed method and compositions. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds may not be explicitly disclosed, each is specifically contemplated
and described herein. Thus, if a class of substituents A 1 B, and C are disclosed as well as a class of substituents D, E, and F and an example of a combination embodiment, A-D is disclosed, then each is individually and collectively contemplated. Thus, in this example, each of the combinations A-E, A-F, B-D, B-E, B-F 1 C-D, C-E, and C-F are specifically contemplated and should be considered disclosed from disclosure of A, B, and C; D 1 E, and F; and the example combination A-D. Likewise, any subset or combination of these is also specifically contemplated and disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E are specifically contemplated and should be considered disclosed from disclosure of A, B, and C; D, E 1 and F; and the example combination A-D. This concept applies to all aspects of this disclosure including, but not limited to any components of the compositions and steps in methods of making and using the disclosed compositions. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the disclosed methods, and that each such combination is specifically contemplated and should be considered disclosed. [0020] In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings: [0021] As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "compound" includes aspects having two or more such compounds, unless the context clearly indicates otherwise.
[0022] "Optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not. For example, the phrase "optionally substituted component" means that the component can or can not be substituted and that the description includes both unsubstituted and substituted aspects of the invention.
[0023] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value.
Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. [0024] As used herein, a "wt. %" or "weight percent" or "percent by weight" of a component, unless specifically stated to the contrary, refers to the ratio of the weight of the component to the total weight of the composition in which the component is included, expressed as a percentage.
[0025] As used herein, a "mole percent" or "mole %" of a component, unless specifically stated to the contrary, refers to the ratio of the number of moles of the component to the total number of moles of the composition in which the component is included, expressed as a percentage.
[0026] Zircon ia is also known as "zirconium dioxide" or ZrO 2 . Alumina is also known as aluminum oxide or AI 2 O 3 .
[0027] As briefly introduced above, the present invention provides for a process for reducing the oxidation for precious metal glass delivery system. The process uses a thermal spray process. Thermal spray techniques are coating processes which involve spraying melted or heated materials onto a surface. The energy to heat the feed stock is typically supplied by electrical means, such as plasma or arc, or chemical means, such as a combustion flame. Any thermal spray technique known in the art can be utilized. Typical thermal spray techniques include, for example, high velocity oxygen-fuel (HVOF), detonation gun (D-gun), flame spraying such as with powder, or plasma spraying such as with powder typically under atmospheric, vacuum, or low pressure conditions, such as for example DC-arc plasma spray, RF induction plasma spray, or plasma transferred arc spray. In one aspect, the thermal spray is a high temperature, high velocity application, such as HVOF, D-gun, or plasma spraying. Such high temperature, high velocity applications can provide preferred results over other thermal spray processes. The thermal spray equipment is well known to those of skill in the art and is readily commercially available.
[0028] The refractory oxide can be any refractory oxide (i.e. ceramic) that can withstand the high temperature of the operating conditions of the glass delivery system. Typically, the refractory oxide has a melting point above the glass delivery system operating temperature. In one aspect the refractory oxide is selected to have a CTE close to that of the precious metal of the glass delivery system. For this aspect, the close match can be, for example, within 5% , 3%, 2%, or 1% of the precious metal CTE.
[0029] In one aspect, the refractory oxide comprises an oxide of Al, Mg, Ti, or Zr or a mixture or alloy thereof. In another aspect, the refractory oxide comprises AI 2 O 3 , MgO, TiO 2 , or ZrO 2 or a mixture or alloy thereof. As used herein, "refractory oxide comprising zirconia" is intended to include ZrO 2 as well as any refractory oxide containing an oxide of zirconium used in combination with additional refractory and/or metal oxides, such that ZrO 2 is in the stoichiometric formula. That is, "refractory oxide comprising zirconia" is intended to include a zirconia as well as any zirconia based refractory oxide. The additional refractory or metal oxides can be, for example, ionically and/or covalently bonded to or associated with the ZrO 2 or can be a separate phase. Thus, a "refractory oxide comprising zirconia" is also intended to include, for example, ZrO 2 5CaO. Similarly, other refractory and/or metal oxides can be included in the stoichiometric formula for refractory oxides comprising AI 2 O 3 , MgO, or TiO 2 , as described above for ZrO 2 . That is, "refractory oxide comprising Al 2 θ 3 , MgO, or TiO 2 " is intended to include AI 2 O 3 , MgO, or TiO 2 as well as any AI 2 O 3 , MgO, or TiO 2 based refractory oxide. In one specific aspect, the refractory oxide comprises zirconia or an alloy thereof.
[0030] The refractory oxides can include, but are not limited to, for example, AI 2 O 3 , AI 2 O 3 in combination with TiO 2 or MgO Spinel, MgO, TiO 2 , ZrO 2 , or ZrO 2 in combination with CaO, CeO 2 , MgO, or Y 2 O 3 . The refractory oxides can specifically include, but are not limited to, for example, AI 2 O 31 AI 2 O 3 2.5TiO 2 , AI 2 O 3 3TiO 2 , > AI 2 O 3 13TiO 2 , AI 2 O 3 40TiO 2 , AI 2 O 3 50TiO 2 , 72 wt.% AI 2 O 3 / 28 wt.% MgO Spinel, MgO, TiO 2 , ZrO 2 , ZrO 2 5CaO, ZrO 2 23CeO 2 , ZrO 2 22MgO, ZrO 2 8Y 2 O 3 , or ZrO 2 20Y 2 O 3 or a mixture or alloy thereof. As conventionally used, unless stated to the contrary, the number preceding the second refractory oxide in the stoichiometric
fomula refers to the weight percent of that second refractory oxide. Thus, AI 2 O 3 2.5TiO 2 refers to 97.5 weight % AI 2 O 3 and 2.5 weight % TiO 2 . Refractory oxides are well known in the art.
[0031] As used herein, the invention does not include a flame sprayed refractory oxide comprising alumina. A refractory oxide comprising alumina can be used if a higher temperature and velocity thermal process is used, such as, for example, plasma spray, HVOF, or detonation gun.
[0032] The refractory oxide comprising zirconia used for the anti-oxidation coating can be, in various aspects, fully stabilized or partially stabilized zirconia. In this aspect, the fully stabilized or partially stabilized zirconia is typically stabilized with Ca, Mg, and/or Y. In one aspect, the zirconia is stabilized with Ca. Typically, the zirconia powder is stabilized with from about 3 to about 10 wt. % of the stabilizing component. In one aspect, the use of a fully stabilized zirconia creates a close CTE match to the precious metal of Pt-20 Rh, and typically a closer CTE match than that of an alumina coating.
[0033] The refractory oxide forms a coated layer typically having a thickness of, in one aspect, from 0.001 inches to 0.060 inches, in another aspect from 0.003 inches to 0.03 inches, and in another aspect from 0.005 inches to 0.015 inches. [0034] The precious metal glass delivery systems of the present invention can be any component of the precious metal glass delivery system, including any refractory metal vessel or transfer component of the system, that requires oxidation protection. In various aspects, the glass delivery system component can be one or more of a pre-melt exit tube, pre-melt finer tube, finer, finer exit, finer to stir chamber connector tube, stir chamber, stirrer, stir chamber cover, windings, stir chamber to bowl connector tube, bowl, downcomer, or inlet. The bowl is a part of the delivery system between the stir chamber and inlet in the glass manufacturing system. The downcomer feeds into the inlet and the inlet feeds the glass into the isopipe. [0035] Typically, the precious metal of the precious metal glass delivery system comprises platinum or a platinum alloy. The platinum can comprise a further metal, typically of at least one of rhodium, ruthenium, palladium, osmium, rhenium, or
iridium. In one aspect, the precious metal is platinum with 20 wt. % rhodium (Pt- 20 Rh).
[0036] The refractory oxide is thermally sprayed to the exterior surface of the precious metal delivery system such that the refractory oxide is in contact with the precious metal of the precious metal delivery system. The refractory oxide is sprayed until sufficient coating thickness is achieved.
[0037] In another embodiment, after the thermally sprayed refractory oxide is applied to the precious metal glass delivery system, a refractory castable material or ceramic castable material is applied to the thermally sprayed refractory oxide. The refractory or ceramic castable material can serve as an insulator and/or for structural strength for support of the glass delivery system. In various aspects, the castable material comprises zirconia or alumina. In one aspect, the castable material is applied to the thermally sprayed refractory oxide and is contact with the thermally sprayed refractory oxide. In another aspect, the castable material is proximate to the support brickwork of the glass delivery system process and in another aspect is in contact with such brickwork.
[0038] The present invention provides better oxidation protection of precious metal delivery systems, therefore providing a longer delivery system life. With the oxidation protection of the current invention, potentially up to double or triple the standard life can be achieved for the delivery system versus the standard life with a Rokide ® alumina flame sprayed coating. Additionally, the coating adds strength to the delivery system component; therefore, in one aspect it is possible to reduce the precious metal thickness, thereby offering significant cost reductions. At high temperatures, the refractory oxide coating is an electron conductor, which allows for applying DC bias to control hydrogen permeation, as described in U.S. Patent No. 6,993,936 B2, the disclosure of which is herein incorporated by reference in its entirety, and for the specific disclosure of applying a DC bias to control the hydrogen permeation.
[0039] In this invention, thermally sprayed refractory oxide reduces the oxidation rate over prior systems. See Figure 1 and Table 1 of Example 1.
[0040] Additionally, the thermally sprayed refractory oxide can have improved crack resistance. Flame sprayed Rokide ® undergoes a phase change at elevated temperatures from gamma to the denser alpha resulting in shrinkage cracks. However, in certain aspects, the thermally sprayed refractory oxide is a single phase (cubic) at room temperature as well as at elevated temperature and therefore does not crack. In one such aspect, the refractory oxide can comprise, for example, zirconia. This is a large advantage over flame sprayed Rokide ® because accelerated platinum oxidation occurs at coating cracks, and the eventual breach of the platinum component wall is a major cause of glass leaks. See, for example, Figure 2, which shows the enhanced crack resistance. Figure 2A shows Rokide ® flame sprayed coating after 10 days, whereas Figure 2B shows plasma sprayed zirconia after 40 days. The flame sprayed Rokide ® experiences cracks up to 3 / 16 -inch long whereas the plasma sprayed zirconia shows no cracking.
[0041] Additionally, the thermal expansion rate of certain thermally sprayed refractory oxides can be matched to that of the precious metal of the glass delivery system. For example, the CTE of fully stabilized zirconia is virtually identical to Pt- 20 Rh while flame sprayed Rokide ® has 14% lower rate than Pt-20 Rh. This is important for coating integrity, especially during heat up of the delivery system. See Figure 3, which compares the linear expansion versus temperature for precious metal, plasma sprayed zirconia and flame sprayed alumina.
[0042] Another advantage of the invention is that the oxidation (refractory oxide) coating of the present invention can be applied directly to the precious metal of the precious metai delivery system without any interceding layer, such as a bond coating layer. In another aspect, no further protection layer is required on the outside of the refractory oxide coating.
[0043] Although several aspects of the present invention have been described in the detailed description, it should be understood that the invention is not limited to the aspects disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the spirit of the invention as set forth and defined by the following claims.
EXAMPLES
[0044] To further illustrate the principles of the present invention, the following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compositions, articles, devices, and methods claimed herein are made and evaluated. They are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperatures, etc.); however, some errors and deviations should be accounted for. Unless indicated otherwise, temperature is 0 C or is at ambient temperature, and pressure is at or near atmospheric. There are numerous variations and combinations of process conditions that can be used to optimize product quality and performance. Only reasonable and routine experimentation will be required to optimize such process conditions. [0045] Example 1
[0046] The oxidation rate after 40 days at 167O 0 C was compared using a Pt- 20 Rh delivery system material and uncoated, flame sprayed Rokide ® coated, and two different coating thicknesses of plasma sprayed zirconia (PSZ). The results of that comparison are shown below in Table 1. See also Figure 1.
Table 1. Oxidation Rate after 40 days at 1670 0 C
[0047] Various modifications and variations can be made to the compositions, articles, devices, and methods described herein. Other aspects of the compositions, articles, devices, and methods described herein will be apparent from consideration of the specification and practice of the compositions, articles, devices, and methods
disclosed herein. It is intended that the specification and examples be considered as exemplary.