US3446643A - Method of coating articles with titanium and related metals and the article produced - Google Patents

Method of coating articles with titanium and related metals and the article produced Download PDF

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US3446643A
US3446643A US441933A US3446643DA US3446643A US 3446643 A US3446643 A US 3446643A US 441933 A US441933 A US 441933A US 3446643D A US3446643D A US 3446643DA US 3446643 A US3446643 A US 3446643A
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titanium
coating
metallizing
metal
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Robert F Karlak
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Lockheed Corp
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    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/06Surface treatment of glass, not in the form of fibres or filaments, by coating with metals
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/50Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
    • C04B41/51Metallising, e.g. infiltration of sintered ceramic preforms with molten metal
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/50Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
    • C04B41/51Metallising, e.g. infiltration of sintered ceramic preforms with molten metal
    • C04B41/5133Metallising, e.g. infiltration of sintered ceramic preforms with molten metal with a composition mainly composed of one or more of the refractory metals
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81Coating or impregnation
    • C04B41/85Coating or impregnation with inorganic materials
    • C04B41/88Metals
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2217/00Coatings on glass
    • C03C2217/20Materials for coating a single layer on glass
    • C03C2217/25Metals
    • C03C2217/263Metals other than noble metals, Cu or Hg
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2218/00Methods for coating glass
    • C03C2218/10Deposition methods
    • C03C2218/17Deposition methods from a solid phase
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12014All metal or with adjacent metals having metal particles
    • Y10T428/12021All metal or with adjacent metals having metal particles having composition or density gradient or differential porosity
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12014All metal or with adjacent metals having metal particles
    • Y10T428/12028Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
    • Y10T428/12049Nonmetal component
    • Y10T428/12056Entirely inorganic
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12014All metal or with adjacent metals having metal particles
    • Y10T428/12028Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
    • Y10T428/12063Nonparticulate metal component
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12597Noncrystalline silica or noncrystalline plural-oxide component [e.g., glass, etc.]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12639Adjacent, identical composition, components
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771Transition metal-base component
    • Y10T428/12778Alternative base metals from diverse categories

Definitions

  • FIG.2 METHOD OF COATING ARTICLES WITH TITANIUM AND RELATED METALS AND THE ARTICLE PRODUCED Filed March 22, 1965 l4 ACTIVELY SINTERED TITANIUM LAYER TRANSITION nnmuu LAYER ALUMINA suasmu's Q FIG.2
  • This invention relates to an improved metal coating of titanium and related metals for articles, and more particularly, to an improved metal coating of titanium and related metals for articles wherein the novel coating is applied to the surface of the article or portions thereof which are traditionally difficult to reach or in patterns of preselected design by use of an improved method of coating the articles.
  • metals like titanium, zirconium, hafnium and uranium possess certain desirable properties which make them useful for coating various surfaces of articles. It has been discovered that the use of such metal coatings, particularly titanium, on the surface articles such as glass, quartz, beryllia, ceramic, porcelain, and the like, oifer several important advantages for both printed and integrated electronic circuitry applications and for brazing and vacuum sealing techniques.
  • the present invention is particularly directed to the application of titanium to an article for brazing and vacuum sealed techniques, but it is to be expressly understood that the invention may also be applicable for other purposes such as printed and integrated electronic circuitry, for example, and encompasses the utilization of such metals as zirconium, hafnium and uranium as well as titanium.
  • coating articles with titanium and related metals is specifically disclosed in US. Patent Nos. 2,732,321, 2,996,401, and 3,022,201.
  • the methods disclosed in the cited patents involve applying a coating by means of 1) immersing the article to be coated in a fused inorganic material bath of alkali metal halides or alkaline earth metal halides while holding a sheet of titanium in approximately the same surface area as the surface of the article to be plated or with powdered titanium packed around the article to be plated, the article and the titanium both being immersed in the bath, thereby causing metallizing of the article with titanium; (2) applying a metallizing mixture to the article to be coated by means of brushing, spraying, printing or otherwise, where the mixture consists essentially of a powdered manganese and titanium with a powdered metal selected from the group consisting of powdered molybdenum or tungsten in a suitable binding agent such as nitrocellulose and heating to form a crystalline structure with the article to produce an interface zone which is chemical in nature rather than mechanical; and (3) applying a coating by means of a three-layer sandwich assembly having an outer layer of titanium or titanium alloy, another outer layer
  • the article can be coated only in the area where it is possible to place the titanium, titanium powder or titanium alloy in close proximity to the surface to be coated on the article by some jigging means which in general is rather difiicult, impractical and uneconomical for mass production techniques so that the processes are generally limited to fiat surfaces, or to those surfaces which are readily amenable to a sandwich arrangement; or that the titanium must be a part of the metallizing mixture and the resulting coating is not substantially a titanium one but a mixture of the metals and the oxides of the metals utilized in the metallizing mixture.
  • divalent titanium which may be introduced into a fused salt bath in several ways.
  • the most commonly used divalent compounds are titanium dichloride, titanium di-iodide or titanium dibromide and the like, and these divalent salts are pyrophoric and must be handled with extreme care to avoid possible harm to the workmen coating articles with titanium.
  • these compounds are highly objectionable since they create a hazard to the workmen.
  • the present invention obviates the foregoing and other disadvantages of the prior art by first providing a novel metallic surface coating composition which has not been realized heretofore in the prior art, and, if realized, has not been heretofore recognized and utilized in the manner and for the purposes contemplated by the present invention.
  • the present invention provides an improved method for coating irregularly shaped bodies, both small and large surfaces, Whether solid or hollow, and in coating preselected areas by appropriate application techniques when the improved coating mixture, of the present invention, is utilized.
  • the present invention provides for a novel metal coating composition and an appropriate process and metallizing solution whereby metals such as titanium, zirconium, hafnium, and uranium may be applied to a surface of an article in a manner heretofore considered impossible, without the attendant contamination associated with the prior art techniques.
  • the present invention also provides the advantages of a technique and material which makes the metallizing process substantially more economical and easy to apply to both small and large sized bodies without the necessity of the attendant care required if pyrophoric materials are used, or without fear of shattering the article resulting from quick changes in temperature as when the article is dipped into a molten bath.
  • the present invention provides a method vherein sharply defined pattern edges are possible be- :ause of the particle size of the metallizing material utiized, and also provides a resulting coating which adheres enaciously to the article being coated which is extremely tdvantageous for most applications.
  • a more specific objective of the invention is to provide an improved and simplified method for forming a novel metal coating composition of titanium on an article of a preselected pattern and on preselected portion of the body.
  • Another object of this invention is to provide a simplified and economical method for forming a thin uniform conductive film on flat, irregular, or curved surfaces of the body of a preselected pattern and on preselected area thereof which is readily adaptable for semi-automatic or mass production techniques.
  • Still another object of this invention is to provide a metallizing solution which may be utilized to readily deposit reproducible and uniform metal coating compositions on irregularly shaped bodies in intricate patterns which is more economical and practical than heretofore known.
  • the present invention provides a novel metal coating composition for articles which is derived from utilizing a new and improved method for coating articles in preselected areas or patterns on regular or irregular body configurations though the use of a unique metallizing coating which is adaptable for use with conventional spray equipment and masking techniques and the like.
  • the novel metal coating composition is derived from a unique metallizing solution of the present invention which comprises a mixture of any one or a mixture of the alkali or alkaline earth metal halides selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, lithium chloride, and the like, and water in a saturated suspension solution, and powdered metal selected from the group of titanium, hafnium, zirconium and uranium.
  • the article After the metallizing coating, which comprises the salts and metal particles in a recrystallized form, has been applied to the article, the article is heat treated in a controlled atmosphere at a relative low temperature.
  • the constituents of this coating material are in such proportions as to eliminate traditional run-off and to assure ready adherence when applied in accordance with the teachings of the present invention or when subjected to the heat treatment step.
  • FIGURES 1 and 2 are photomicrographs of sections through several ceramic substrates showing the thin transition film layer of titanium, bonded to the ceramic substrates and the porous thicker layers of actively sintered titanium particles sintered to the thin transition layer.
  • the metallizing solution comprises a mixture of finely divided metal particles, such as titanium, for example, having a U8. sieve number of 300 or greater, and preferably greater than 325, any one or a mixture of the alkali and alkaline earth metal halide salts in preselected proportions and water as the liquid vehicle. It should be understood at this point that particles that will pass through a mesh with a 325 US. sieve number, have a diameter less than 0.0017 inch.
  • an excellent metal coating may be produced by utilizing a metallizing solution having by weight the following ranges:
  • the metallizing solution thus formed results in a saturated salt solution in which is suspended the metal particles.
  • the solution should be thoroughly mixed so as to provide as uniform a distribution of the titanium particles as possible throughout the liquid.
  • the particle size of the metal constituent and the presence of calcium chloride are considered essential to the solution for successful deposition.
  • the calcium chloride provides beneficial assistance in promoting adhesion during the application of the saturated metallizing suspension solution to the article and also enhances the rate of deposition to produce uniform metallizing coating of the article during deposition.
  • the metallizing mixture does not adhere to the surface of the article to be coated during its application as well as when it is present.
  • the calcium chloride contributes a moist phase to the metallizing mixture, which serves to make it more adherent to the surface of the article during its application, and heat treating steps.
  • the particle size of the metal it has been found that if the size is on the order of 250 US. sieve number the metallizing mixture will not produce a coat of uniform thickness and, in addition, may be irregular and spotty in its coverage of the article.
  • Such a coating is unsatisfactory as either a base material for over-plating with another metal for brazing or as an electrical conductor when the coating pattern is employed as circuit wiring or as a base material for electrical components on a substrate, such as capacitors and resistors.
  • Preparation of the articles to be coated may be commenced by thoroughly cleaning the article and then applying a uniform coating of the metallizing solution to the article by means of spray or painting techniques.
  • the metallizing material preferably may be applied with suitable spray equipment, such as a standard spray gun usable in spraying heavy duty paints.
  • suitable spray equipment such as a standard spray gun usable in spraying heavy duty paints.
  • the pressure employed in applying such materials is not critical, but should be of a magnitude such that the metal particles in the metallizing mixture are propelled with sufiicient force to insure their adherence to the surface to be coated. It has. been found that air and the metallizer solution when sprayed in the ratio of 1 volume solution 300 volumes air is satisfactory for the present process.
  • the metallizing mixture is produced by mixing together the dry salts potassium chloride, sodium chloride, calcium chloride and titanium particles. The dry metallizing mixture is then mixed with the water to produce a saturated metallizing solution with the metal particles in suspension. The solution must be thoroughly stirred prior to application and should be stirred continuously during the application step for best results, unless the metal particles are very fine, so as to stay continuously in suspension.
  • the spray application step it is preferable during the spray application step to move the article being coated or to move the spraying device so as to progressively expose different surface portions of the article to the spray stream of the metallizing mixture. In this manner a more uniform coat may be obtained.
  • the article is next subjected to a heat treatment step wherein the article is elevated to a temperature range of about 1200 F. to 1600 F. in a controlled atmosphere for a time period of about 5 to 120 minutes.
  • Heating of the coated article in a controlled atmosphere such as argon, nitrogen, or forming gas, for examples, prevents oxidation of the deposited titanium.
  • gases as forming gas, is highly desirable because it is readily available commercially at low cost.
  • the alkali and alkaline earth metal halide salts go through a fluid state and thereby cause a molecular transfer to the surface of the article from the titanium particles to form a transition film layer bonded thereto, and then the finely divided metal particles are actively sintered directly over the transition layer.
  • the melted salts occupy the interparticle volume and serve as the mass-transfer medium for activating the sintering of the particles.
  • the article is then slowly cooled to room temperature in the protective controlled atmosphere whereupon the remaining salts and metal particles which have not reacted during the heating step are removed by rinsing in water.
  • FIGURES 1 and 2 respectively, there is shown photomicrographs of sections through ceramic substrates 10 and 16 which have first thin transition film layers 12 and 18, and second porous metallic layers 14 and 20 previously referred to as agglomerate layers.
  • layers 12 and 18 are bonded to the surfaces of the ceramic articles 10 and 16 while the porous layers 14 and 20 are in turn bonded to layers 12 and 18.
  • a closer analysis of the composition formed under magnification of at least 250 times reveals that the thin layers 12 and 18 are thin continuous layers having a relative density on the order of to percent, while the porous layers 14 and 20 have a relative density on the order of 2050 percent.
  • the exact nature of formation of the metal surface coating composition is not exactly known or completely understood; however, it has been theorized that the thin transition film layer is a result of molecular or ion transfer from the metal particles activated by the molten salts during the heat treatment step. It is believed that this process precedes or is concurrent with the formation of the porous, agglomerate layer which is bonded to the transition layer. Formation of the porous layer is theorized as resulting from the process known as activated sintering. However, the sintering process is one which depends upon the presence of the molten alkali or alkaline earth metal salts which act as an activator in the process. Thus, the metal particles are caused to be fused together in a porous configuration and are formed substantially simultaneously with the thin transition layer owing to the presence of the activator salts in the metallizing coating.
  • FIGURE 1 a substantially less dense layer is shown in FIGURE 1, layer 14, than that which is shown in FIGURE 2, layer 20.
  • the thickness of the porous layers 14 and 20 may be varied in several ways; namely, by varying the quantity of metal particles in the metallizing solution or by varying the quantity of solution applied to the article prior to the heat treatment step.
  • brazing to another article with a suitable brazing alloy may be accomplished by brazing directly to the resultant coating.
  • An excellent braze joint results having tensile strength as good as, and in most instances better than heretofore obtained with the prior art coatings.
  • More specifically in the prior art high strength seals have been made employing metallizing composition of molybdenum and manganese.
  • the resulting coating is known to have and to be predicated upon a glassy transition phase for its strength. In certain applications the presence of the glassy transition phase is extremely objectionable because it introduces undesirable and poor thermal properties. Such undesirable thermal properties have appeared when the molybdenum-manganese process is employed especially with beryllia.
  • the present invention provides a versatile and inexpensive process whereby the end product of the present invention may be produced.
  • the resulting coating may be utilized as a metallic layer which provides an excellent conductor for wiring patterns or may be employed as a base for a second coating which may be useful for a soldering or brazing surface, either with or without a plating layer thereon, depending upon the application.
  • the thin conductive film deposited by the metallizing process in accordance with the present invention is to be used as a wiring circuit pattern on an article, for example a ceramic circuit board, there is no need to further process the film and it may be used directly for purposes of providing a conductive wiring or circuit pattern.
  • the conductive or electrical characteristics of the metal deposited on an article are similar to the characteristics of the metal films deposited according to the process disclosed in United States Patent No. 3,022,201 by Ross A. Quinn and Robert F. Karlak.
  • the thin film obtained by mechanically removing a substantial portion of the agglomerate layer deposited in accordance with the present process may be readily adaptable to microminiature electrical circuits wherein resistors and capacitor elements may be produced on a substrate by means of anodizing in accordance with known technology in the prior art.
  • One such advantage involves the use of water as a substitute for an organic binder or vehicle which has been used in the prior art processes.
  • organic binders in combination with alkali or alkaline salts in general create undesirable problems of a chemical nature.
  • the interaction of organic compounds with the salts in particular the interaction of organic compounds with the salts.
  • the use of organic binders is substantially more costly and critical than the use of water for mixing the solution and therefore causes the mixture to be more costly.
  • Another advantage of the present invention arises from the fact that the ingredients used in the metallizing solution in the prescribed proportion provide a solution which readily adheres to the surface of the article when applied thereto and thereby provides a uniform coating thereon.
  • Yet another advantageous aspect of the present invention is that the types of materials used in the mixture disclosed by the present invention are much more economical than that employed in prior art techniques.
  • the materials required for depositing single layer thin films on substrate as disclosed by U.S. Patent No. 3,022,201 require the use of a thin sheet of titanium or titanium foil which is substantially more costly than the titanium particles which are utilized in the present invention.
  • the titanium particles are extremely small and are placed directly on the surface to be coated along with the salts associated therewith, there is substantially greater and more efiicient coverage, on the order of ten times as much, derived from the same quantity of salts which will be used in the process as disclosed in the aforementioned patent.
  • Another advantage results from the fact that the metallic film can be applied by this process to any surface regardless of shape, contour, or orientation.
  • the present process is one that is considerably more economical, practical, and versatile than any process heretofore known.
  • Still another advantage of the present invention arises from the fact that the resulting metal coating has the properties of being useful for both brazing or soldering ceramic to ceramic, ceramic to metal, or the like especially when a suitable second plating coat is applied to the initial metallizing coat, or as an electrical conductor for the wiring of circuit patterns or for microminiature electrical components such as resistors and capacitors when portions of the surface are anodized according to techniques known heretofore in the prior art.
  • a process for forming a metal coating on the surface of an article of glass, quartz, beryllia, ceramic or porcelain which comprises raising the article to an elevated temperature, applying a metallizing solution to the surface of said article to form a metallizing coating thereon, said solution consisting essentially of at least one salt chosen from the group consisting of alkali metal halides and alkaline earth metal halides, metal particles from the group consisting of titanium, zirconium, hafnium and uranium, and water, and then heating the article with said metallizing coating thereon to a predetermined temperature in a non-oxidizing atmosphere for a time sufficient to melt the salts in the metallizing coating and to "cause sintering of the metal coating consisting essentially of a thin transition layer and a second porous layer bonded to said first layer, the quantity of salts in the metallizing coating initially being suflicient to provide fluid boundary between the individual metal particles, and the metal particles and the surface of the article to be coated when the salt melts.
  • the method of metallizing an article of glass, quartz, beryllia, ceramic or porcelain to provide a surface suitable for bonding to a metal, or metallized article to form between two articles a vacuum type joint of high mechanical strength which comprises coating said article with a metallizing coating from a metallizing solution consisting of one percent to fifty percent by weight of titanium particles, one percent to twenty percent by weight of one or more of the alkaline earth metal halides, one percent to ninety percent by weight of one or more of the alkali metal halides, and the remainder of water, and then firing the coated article in a non-oxidizing atmosphere at a temperature at least as high as the melting temperature of the alkali and alkaline halide salts for a preselected period of time to cause sintering of the metal particles.
  • a metallized ceramic article comprising a ceramic article, a first thin metallic film transition layer bonded to the surface of said ceramic article, said film having a relative density of about to percent, a second metallic porous layer bonded to said transition layer, said second layer having a relative density of about 20 to 50 percent and comprising actively sintered metal particles of the same material as said transition layer selected from the group essentially consisting of titanium, hafnium, zirconium, and uranium, said first and second layers being formed substantially simultaneously from a metallizing coating deposited on said article essentially consisting of at least one salt selected from the group consisting of alkali metal halides and alkaline earth halides, metal particles selected from the group essentially consisting of titanium, hafnium, zirconium, and uranium applied to said article to a metal coat thereon which is bonded to said ceramic article after being heat treated.
  • a metallized ceramic article comprising a ceramic article and a first thin-metallic film layer bonded to said ceramic article and a second porous metallic layer bonded to said first layer, said first and second layers being of the same metal and selected from the group essentially consisting of titanium, hafnium, zirconium, and uranium, said first layer at the surface of the ceramic article being in a form of a continuous transitional layer having a relative density of about 90 to 100 percent and said second layer being in the form of actively sintered metal particles having a relative density of about 20 to 50 percent.
  • a metallized article of glass, quartz, beryllia, ceramic or porcelain comprising a first thin film transition layer bonded to the surface of said article, said transition layer having a relative density of 90 to 100 percent, and a second porous agglomerate layer bonded to said transition layer, said second layer having a relative density of about 20 to 50 percent essentially consisting of actively sintered titanium particles derived from titanium having a particle size of at least 250 U.S. sieve size.
  • a metallized article of glass, quartz, beryllia, ceramic or porcelain comprising a first thin metallic film transition layer bonded to the surface of said article, said film having a relative density of about 90 to 100 percent, a second metallic porous layer bonded to said transition layer, said second layer having a relative density of about 20 to 50 percent and comprising actively sintered metal particles of the same material as said transition layer, said first and second layers being formed substantially simultaneously from a metallizing coating deposited on said article said metallizing coating being derived from a salt, essentially consisting of at least one salt selected from the group consisting of alkali metal and alkaline metal halides, metal particles and water as a metallizing coating to said article and being bonded to said article by activated sintering as the coated article is heated.
  • first and second layers are further defined as being selected from the group essentially consisting of titanium, hafnium, zirconium and uranium.

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Description

May 27, .1969 R. F. KARLAK 3,446,543
METHOD OF COATING ARTICLES WITH TITANIUM AND RELATED METALS AND THE ARTICLE PRODUCED Filed March 22, 1965 l4 ACTIVELY SINTERED TITANIUM LAYER TRANSITION nnmuu LAYER ALUMINA suasmu's Q FIG.2
' ACTIVELY smrenzo TITANIUM LAYER IB TRANSITION LAYER N's ALUMINA SUBSTRATE INVENTOR. ROBERT F. KARLAK Agent United States Patent 3,446,643 METHOD OF COATING ARTICLES WITH TI- TANIUM AND RELATED METALS AND THE ARTICLE PRODUCED Robert F. Karlak, Sunnyvale, Calif., assignor to Lockheed Aircraft Corporation, Burbank, Calif. Filed Mar. 22, 1965, Ser. No. 441,933 Int. Cl. C23c 3/04, 13/04; C03c 25/02 US. Cl. 117-22 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an improved metal coating of titanium and related metals for articles, and more particularly, to an improved metal coating of titanium and related metals for articles wherein the novel coating is applied to the surface of the article or portions thereof which are traditionally difficult to reach or in patterns of preselected design by use of an improved method of coating the articles.
In the prior art it is well known that metals like titanium, zirconium, hafnium and uranium possess certain desirable properties which make them useful for coating various surfaces of articles. It has been discovered that the use of such metal coatings, particularly titanium, on the surface articles such as glass, quartz, beryllia, ceramic, porcelain, and the like, oifer several important advantages for both printed and integrated electronic circuitry applications and for brazing and vacuum sealing techniques.
The present invention is particularly directed to the application of titanium to an article for brazing and vacuum sealed techniques, but it is to be expressly understood that the invention may also be applicable for other purposes such as printed and integrated electronic circuitry, for example, and encompasses the utilization of such metals as zirconium, hafnium and uranium as well as titanium. In the prior art, coating articles with titanium and related metals is specifically disclosed in US. Patent Nos. 2,732,321, 2,996,401, and 3,022,201. The methods disclosed in the cited patents involve applying a coating by means of 1) immersing the article to be coated in a fused inorganic material bath of alkali metal halides or alkaline earth metal halides while holding a sheet of titanium in approximately the same surface area as the surface of the article to be plated or with powdered titanium packed around the article to be plated, the article and the titanium both being immersed in the bath, thereby causing metallizing of the article with titanium; (2) applying a metallizing mixture to the article to be coated by means of brushing, spraying, printing or otherwise, where the mixture consists essentially of a powdered manganese and titanium with a powdered metal selected from the group consisting of powdered molybdenum or tungsten in a suitable binding agent such as nitrocellulose and heating to form a crystalline structure with the article to produce an interface zone which is chemical in nature rather than mechanical; and (3) applying a coating by means of a three-layer sandwich assembly having an outer layer of titanium or titanium alloy, another outer layer of a ceramic substrate to be coated with titanium, and an inner layer sandwiched therebetween of a thin layer of salt comprising any one of a mixture of the alkali or alkaline earth metal halides which is heat-treated to thereby form a titanium thin-film coating on the surface of the article.
The foregoing processes have several undesirable features either singularly or in combination; namely, that the article can be coated only in the area where it is possible to place the titanium, titanium powder or titanium alloy in close proximity to the surface to be coated on the article by some jigging means which in general is rather difiicult, impractical and uneconomical for mass production techniques so that the processes are generally limited to fiat surfaces, or to those surfaces which are readily amenable to a sandwich arrangement; or that the titanium must be a part of the metallizing mixture and the resulting coating is not substantially a titanium one but a mixture of the metals and the oxides of the metals utilized in the metallizing mixture. Thus, the foregoing prior art methods are generally limited to metallizing those surfaces which are readily accessible and whose configurations are regular and uniform. The salts utilized in several of the foregoing patents tend to drip or to run off of the surface being coated onto other portions of the article unless additional precautions are taken to avoid this occurrence. In addition, such salts may be accumulated on the apparatus of other auxiliary equipment being utilized in the process, thereby causing other undesirable corrosive effects. Thus, it can readily be seen that it is highly desirable to provide a process that can easily and economically be controlled which eliminates the necessity for special jigging or fixtures or which is not limited to any configuration while substantially eliminating the possibility of any runoff of the salts or contamination of the equipment by the accumulation of salts during the metallizing process.
In still another area of the prior art it has been found desirable to utilize divalent titanium which may be introduced into a fused salt bath in several ways. The most commonly used divalent compounds are titanium dichloride, titanium di-iodide or titanium dibromide and the like, and these divalent salts are pyrophoric and must be handled with extreme care to avoid possible harm to the workmen coating articles with titanium. Thus it can be seen that the use of these compounds is highly objectionable since they create a hazard to the workmen.
The present invention obviates the foregoing and other disadvantages of the prior art by first providing a novel metallic surface coating composition which has not been realized heretofore in the prior art, and, if realized, has not been heretofore recognized and utilized in the manner and for the purposes contemplated by the present invention. In addition, the present invention provides an improved method for coating irregularly shaped bodies, both small and large surfaces, Whether solid or hollow, and in coating preselected areas by appropriate application techniques when the improved coating mixture, of the present invention, is utilized. More particularly, the present invention provides for a novel metal coating composition and an appropriate process and metallizing solution whereby metals such as titanium, zirconium, hafnium, and uranium may be applied to a surface of an article in a manner heretofore considered impossible, without the attendant contamination associated with the prior art techniques. The present invention also provides the advantages of a technique and material which makes the metallizing process substantially more economical and easy to apply to both small and large sized bodies without the necessity of the attendant care required if pyrophoric materials are used, or without fear of shattering the article resulting from quick changes in temperature as when the article is dipped into a molten bath. Furthermore, the present invention provides a method vherein sharply defined pattern edges are possible be- :ause of the particle size of the metallizing material utiized, and also provides a resulting coating which adheres enaciously to the article being coated which is extremely tdvantageous for most applications.
Accordingly, it is a broad objective of the present inlention to provide a novel metallic surface coating com- ;osition for brazing and vacuum sealing techniques or for 30th printed and integrated electronic circuit applications.
It is another objective of the present invention to prolide an improved method for coating articles with a novel metallic surface coating composition of titanium, zirconium, hafnium and uranium and the like.
A more specific objective of the invention is to provide an improved and simplified method for forming a novel metal coating composition of titanium on an article of a preselected pattern and on preselected portion of the body.
Another object of this invention is to provide a simplified and economical method for forming a thin uniform conductive film on flat, irregular, or curved surfaces of the body of a preselected pattern and on preselected area thereof which is readily adaptable for semi-automatic or mass production techniques.
Still another object of this invention is to provide a metallizing solution which may be utilized to readily deposit reproducible and uniform metal coating compositions on irregularly shaped bodies in intricate patterns which is more economical and practical than heretofore known.
Concisely stated, the present invention provides a novel metal coating composition for articles which is derived from utilizing a new and improved method for coating articles in preselected areas or patterns on regular or irregular body configurations though the use of a unique metallizing coating which is adaptable for use with conventional spray equipment and masking techniques and the like. More particularly, the novel metal coating composition is derived from a unique metallizing solution of the present invention which comprises a mixture of any one or a mixture of the alkali or alkaline earth metal halides selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, lithium chloride, and the like, and water in a saturated suspension solution, and powdered metal selected from the group of titanium, hafnium, zirconium and uranium.
After the metallizing coating, which comprises the salts and metal particles in a recrystallized form, has been applied to the article, the article is heat treated in a controlled atmosphere at a relative low temperature. The constituents of this coating material are in such proportions as to eliminate traditional run-off and to assure ready adherence when applied in accordance with the teachings of the present invention or when subjected to the heat treatment step.
The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation and application, together with further objects and advantages thereof, will be better understood from the following description thereof, in which illustrative embodiments of the invention are disclosed by way of example. It is expressly understood, however, that the disclosed embodiments are for purposes of illustration and description only and do not define limitations of the invention.
FIGURES 1 and 2 are photomicrographs of sections through several ceramic substrates showing the thin transition film layer of titanium, bonded to the ceramic substrates and the porous thicker layers of actively sintered titanium particles sintered to the thin transition layer.
Various and other objects and advantages will be apparent as the nature of this invention is more fully disclosed. More particularly, the above objects are realized by a novel process which comprises c ating the surface of articles such as ceramic, glass and the like, with a metallizing coating by means of spraying or painting or any suitable manner of applying a metallizing solution comprising fine metallic suspension in aqueous salt solution, and then heat-treating the coated article in acontrolled atmosphere for a preselected time interval to thereby deposit the specific metal contained in the metallizing coating on the surface of the article in a novel actively sintered manner to form a sintered agglomerate in a preselected pattern. In accordance with the present invention in the preferred embodiment, the metallizing solution comprises a mixture of finely divided metal particles, such as titanium, for example, having a U8. sieve number of 300 or greater, and preferably greater than 325, any one or a mixture of the alkali and alkaline earth metal halide salts in preselected proportions and water as the liquid vehicle. It should be understood at this point that particles that will pass through a mesh with a 325 US. sieve number, have a diameter less than 0.0017 inch.
In accordance with the teachings of the invention, an excellent metal coating may be produced by utilizing a metallizing solution having by weight the following ranges:
Percent Titanium 1-50 Alkali metal halide salts 1-90 Alkaline earth metals halide salts 1-20 Water, remainder to produce saturated solution.
The metallizing solution thus formed results in a saturated salt solution in which is suspended the metal particles. The solution should be thoroughly mixed so as to provide as uniform a distribution of the titanium particles as possible throughout the liquid.
It should be noted at this point that in one embodiment of the invention the particle size of the metal constituent and the presence of calcium chloride are considered essential to the solution for successful deposition. The calcium chloride provides beneficial assistance in promoting adhesion during the application of the saturated metallizing suspension solution to the article and also enhances the rate of deposition to produce uniform metallizing coating of the article during deposition.
It has been found that when calcium chloride, which is hygroscopic, is omitted that the metallizing mixture does not adhere to the surface of the article to be coated during its application as well as when it is present. Thus, the calcium chloride contributes a moist phase to the metallizing mixture, which serves to make it more adherent to the surface of the article during its application, and heat treating steps. As for the particle size of the metal, it has been found that if the size is on the order of 250 US. sieve number the metallizing mixture will not produce a coat of uniform thickness and, in addition, may be irregular and spotty in its coverage of the article. Such a coating is unsatisfactory as either a base material for over-plating with another metal for brazing or as an electrical conductor when the coating pattern is employed as circuit wiring or as a base material for electrical components on a substrate, such as capacitors and resistors.
Preparation of the articles to be coated may be commenced by thoroughly cleaning the article and then applying a uniform coating of the metallizing solution to the article by means of spray or painting techniques. The metallizing material preferably may be applied with suitable spray equipment, such as a standard spray gun usable in spraying heavy duty paints. The pressure employed in applying such materials is not critical, but should be of a magnitude such that the metal particles in the metallizing mixture are propelled with sufiicient force to insure their adherence to the surface to be coated. It has. been found that air and the metallizer solution when sprayed in the ratio of 1 volume solution 300 volumes air is satisfactory for the present process.
A more complete understanding of the present irrvention may be obtained from the illustrative example. Very good success has been achieved by utilizing a metallizing solution consisting essentially by percent of weight and by a more specific example by weight in grams of the following proportions:
The metallizing mixture is produced by mixing together the dry salts potassium chloride, sodium chloride, calcium chloride and titanium particles. The dry metallizing mixture is then mixed with the water to produce a saturated metallizing solution with the metal particles in suspension. The solution must be thoroughly stirred prior to application and should be stirred continuously during the application step for best results, unless the metal particles are very fine, so as to stay continuously in suspension.
In order to further enhance the deposition onto the surface of the article, it is preferable during the spray application step to move the article being coated or to move the spraying device so as to progressively expose different surface portions of the article to the spray stream of the metallizing mixture. In this manner a more uniform coat may be obtained. Although it is not critical for purposes of this invention, it is preferable as a rule to preheat the article being coated to a temperature of about ZOO-300 F. before applying the metallizing solution while maintaining the article at the elevated temperature if possible during the coating application the actual temperature used is determined by the metallizer solution temperature and that of the propelling air. Such preheating has been found to contribute significantly to the adhesion of the metallizing coating.
After the coating step has been completed the article is next subjected to a heat treatment step wherein the article is elevated to a temperature range of about 1200 F. to 1600 F. in a controlled atmosphere for a time period of about 5 to 120 minutes. Heating of the coated article in a controlled atmosphere, such as argon, nitrogen, or forming gas, for examples, prevents oxidation of the deposited titanium. The use of such gases, as forming gas, is highly desirable because it is readily available commercially at low cost.
During the heat treatment step it is believed that the alkali and alkaline earth metal halide salts go through a fluid state and thereby cause a molecular transfer to the surface of the article from the titanium particles to form a transition film layer bonded thereto, and then the finely divided metal particles are actively sintered directly over the transition layer. During the heat treatment step the melted salts occupy the interparticle volume and serve as the mass-transfer medium for activating the sintering of the particles. The article is then slowly cooled to room temperature in the protective controlled atmosphere whereupon the remaining salts and metal particles which have not reacted during the heating step are removed by rinsing in water.
The exact reaction or mechanism which occurs during the heat treatment of the coated article cannot be stated with any absolute certainty. The exact nature of the deposition is regarded as relatively unimportant since the resulting coating has an electrically conducting coating on which other metals may be plated if such is desired, or may be used for purposes of producing metal-toceramic or ceramic-to-ceramic bonds and the like. Microscopic examination of sections cut from the treated article, however, shows that the thin metallic film is an integral part of the article penetrating into the surface of the article, and that the actively-sintered agglomerate layer is bonded to this thin film layer.
With reference to FIGURES 1 and 2, respectively, there is shown photomicrographs of sections through ceramic substrates 10 and 16 which have first thin transition film layers 12 and 18, and second porous metallic layers 14 and 20 previously referred to as agglomerate layers. As shown in the figures, layers 12 and 18 are bonded to the surfaces of the ceramic articles 10 and 16 while the porous layers 14 and 20 are in turn bonded to layers 12 and 18. A closer analysis of the composition formed under magnification of at least 250 times reveals that the thin layers 12 and 18 are thin continuous layers having a relative density on the order of to percent, while the porous layers 14 and 20 have a relative density on the order of 2050 percent.
As stated hereinabove, the exact nature of formation of the metal surface coating composition is not exactly known or completely understood; however, it has been theorized that the thin transition film layer is a result of molecular or ion transfer from the metal particles activated by the molten salts during the heat treatment step. It is believed that this process precedes or is concurrent with the formation of the porous, agglomerate layer which is bonded to the transition layer. Formation of the porous layer is theorized as resulting from the process known as activated sintering. However, the sintering process is one which depends upon the presence of the molten alkali or alkaline earth metal salts which act as an activator in the process. Thus, the metal particles are caused to be fused together in a porous configuration and are formed substantially simultaneously with the thin transition layer owing to the presence of the activator salts in the metallizing coating.
In the figures a substantially less dense layer is shown in FIGURE 1, layer 14, than that which is shown in FIGURE 2, layer 20. The thickness of the porous layers 14 and 20 may be varied in several ways; namely, by varying the quantity of metal particles in the metallizing solution or by varying the quantity of solution applied to the article prior to the heat treatment step.
With the resulting surface coating composition it has been found that under certain conditions brazing to another article with a suitable brazing alloy may be accomplished by brazing directly to the resultant coating. An excellent braze joint results having tensile strength as good as, and in most instances better than heretofore obtained with the prior art coatings. More specifically in the prior art high strength seals have been made employing metallizing composition of molybdenum and manganese. The resulting coating is known to have and to be predicated upon a glassy transition phase for its strength. In certain applications the presence of the glassy transition phase is extremely objectionable because it introduces undesirable and poor thermal properties. Such undesirable thermal properties have appeared when the molybdenum-manganese process is employed especially with beryllia. It is well known that high purity beryllia has excellent thermal properties and is employed extensively for this reason. A typical high purity beryllia having excellent thermal properties is Thermalox 998 made by The Brush Beryllium Company, Metal and Oxide Division of Elmore, Ohio. However, when the molybdenum-manganese process is modified so as to remove the glassy phase, and to restore its efiicient thermal properties the bond strengths of the brazed joints of beryllia and other similar materials are too low to be usable. The present metal surface composition is not predicated upon a glassy transition phase and consequently, has excellent thermal properties when utilized with beryllia while providing bond strengths heretofore unknown in the prior art.
In addition to the excellent properties of mechanical strength for brazing purposes and thermal conductive which the metal surface composition of the present invention exhibits, the present invention provides a versatile and inexpensive process whereby the end product of the present invention may be produced. Furthermore, the resulting coating may be utilized as a metallic layer which provides an excellent conductor for wiring patterns or may be employed as a base for a second coating which may be useful for a soldering or brazing surface, either with or without a plating layer thereon, depending upon the application.
In the event that the thin conductive film deposited by the metallizing process in accordance with the present invention is to be used as a wiring circuit pattern on an article, for example a ceramic circuit board, there is no need to further process the film and it may be used directly for purposes of providing a conductive wiring or circuit pattern. In addition, it has been found that the conductive or electrical characteristics of the metal deposited on an article are similar to the characteristics of the metal films deposited according to the process disclosed in United States Patent No. 3,022,201 by Ross A. Quinn and Robert F. Karlak. Thus, it can be readily seen that the thin film obtained by mechanically removing a substantial portion of the agglomerate layer deposited in accordance with the present process may be readily adaptable to microminiature electrical circuits wherein resistors and capacitor elements may be produced on a substrate by means of anodizing in accordance with known technology in the prior art.
In closing it is useful to summarize some of the advantages of the present invention. One such advantage involves the use of water as a substitute for an organic binder or vehicle which has been used in the prior art processes. In this connection, it should be noted that the use of such organic binders in combination with alkali or alkaline salts in general create undesirable problems of a chemical nature. In particular the interaction of organic compounds with the salts. In addition, the use of organic binders is substantially more costly and critical than the use of water for mixing the solution and therefore causes the mixture to be more costly.
Another advantage of the present invention arises from the fact that the ingredients used in the metallizing solution in the prescribed proportion provide a solution which readily adheres to the surface of the article when applied thereto and thereby provides a uniform coating thereon.
Yet another advantageous aspect of the present invention is that the types of materials used in the mixture disclosed by the present invention are much more economical than that employed in prior art techniques. For example, the materials required for depositing single layer thin films on substrate as disclosed by U.S. Patent No. 3,022,201 require the use of a thin sheet of titanium or titanium foil which is substantially more costly than the titanium particles which are utilized in the present invention. In addition, owing to the fact that the titanium particles are extremely small and are placed directly on the surface to be coated along with the salts associated therewith, there is substantially greater and more efiicient coverage, on the order of ten times as much, derived from the same quantity of salts which will be used in the process as disclosed in the aforementioned patent. Another advantage results from the fact that the metallic film can be applied by this process to any surface regardless of shape, contour, or orientation. Thus, it can readily be seen that the present process is one that is considerably more economical, practical, and versatile than any process heretofore known.
Still another advantage of the present invention arises from the fact that the resulting metal coating has the properties of being useful for both brazing or soldering ceramic to ceramic, ceramic to metal, or the like especially when a suitable second plating coat is applied to the initial metallizing coat, or as an electrical conductor for the wiring of circuit patterns or for microminiature electrical components such as resistors and capacitors when portions of the surface are anodized according to techniques known heretofore in the prior art.
What is claimed is:
1. A process for forming a metal coating on the surface of an article of glass, quartz, beryllia, ceramic or porcelain which comprises raising the article to an elevated temperature, applying a metallizing solution to the surface of said article to form a metallizing coating thereon, said solution consisting essentially of at least one salt chosen from the group consisting of alkali metal halides and alkaline earth metal halides, metal particles from the group consisting of titanium, zirconium, hafnium and uranium, and water, and then heating the article with said metallizing coating thereon to a predetermined temperature in a non-oxidizing atmosphere for a time sufficient to melt the salts in the metallizing coating and to "cause sintering of the metal coating consisting essentially of a thin transition layer and a second porous layer bonded to said first layer, the quantity of salts in the metallizing coating initially being suflicient to provide fluid boundary between the individual metal particles, and the metal particles and the surface of the article to be coated when the salt melts.
2. The method of metallizing an article of glass, quartz, beryllia, ceramic or porcelain to provide a surface suitable for bonding to a metal, or metallized article to form between two articles a vacuum type joint of high mechanical strength, which comprises coating said article with a metallizing coating from a metallizing solution consisting of one percent to fifty percent by weight of titanium particles, one percent to twenty percent by weight of one or more of the alkaline earth metal halides, one percent to ninety percent by weight of one or more of the alkali metal halides, and the remainder of water, and then firing the coated article in a non-oxidizing atmosphere at a temperature at least as high as the melting temperature of the alkali and alkaline halide salts for a preselected period of time to cause sintering of the metal particles.
3. A metallized ceramic article comprising a ceramic article, a first thin metallic film transition layer bonded to the surface of said ceramic article, said film having a relative density of about to percent, a second metallic porous layer bonded to said transition layer, said second layer having a relative density of about 20 to 50 percent and comprising actively sintered metal particles of the same material as said transition layer selected from the group essentially consisting of titanium, hafnium, zirconium, and uranium, said first and second layers being formed substantially simultaneously from a metallizing coating deposited on said article essentially consisting of at least one salt selected from the group consisting of alkali metal halides and alkaline earth halides, metal particles selected from the group essentially consisting of titanium, hafnium, zirconium, and uranium applied to said article to a metal coat thereon which is bonded to said ceramic article after being heat treated.
4. A metallized ceramic article comprising a ceramic article and a first thin-metallic film layer bonded to said ceramic article and a second porous metallic layer bonded to said first layer, said first and second layers being of the same metal and selected from the group essentially consisting of titanium, hafnium, zirconium, and uranium, said first layer at the surface of the ceramic article being in a form of a continuous transitional layer having a relative density of about 90 to 100 percent and said second layer being in the form of actively sintered metal particles having a relative density of about 20 to 50 percent.
5. A metallized article of glass, quartz, beryllia, ceramic or porcelain comprising a first thin film transition layer bonded to the surface of said article, said transition layer having a relative density of 90 to 100 percent, and a second porous agglomerate layer bonded to said transition layer, said second layer having a relative density of about 20 to 50 percent essentially consisting of actively sintered titanium particles derived from titanium having a particle size of at least 250 U.S. sieve size.
6. A metallized article of glass, quartz, beryllia, ceramic or porcelain comprising a first thin metallic film transition layer bonded to the surface of said article, said film having a relative density of about 90 to 100 percent, a second metallic porous layer bonded to said transition layer, said second layer having a relative density of about 20 to 50 percent and comprising actively sintered metal particles of the same material as said transition layer, said first and second layers being formed substantially simultaneously from a metallizing coating deposited on said article said metallizing coating being derived from a salt, essentially consisting of at least one salt selected from the group consisting of alkali metal and alkaline metal halides, metal particles and water as a metallizing coating to said article and being bonded to said article by activated sintering as the coated article is heated.
7. The metallized article defined in claim 6 wherein said first and second layers are further defined as being selected from the group essentially consisting of titanium, hafnium, zirconium and uranium.
References Cited UNITED STATES PATENTS 1,922,254 8/1933 McCulloch ll7l60 X 2,732,321 1/1956 Gill et a1 117-131 2,746,888 5/1956 Ross 117123 X 2,991,195 7/1961 Quinn l1716()X 2,996,401 8/1961 Welch et al. 117123 X 3,022,201 2/1962 Quinn et a1 117221 FOREIGN PATENTS 104,564 7/1938 Australia.
ALFRED L. LEAVI'IT, Primary Examiner. T. E. BOKAN, Assistant Examiner.
US. Cl. X.R. 65-32, 43, 59, 60; 1061, 38.27, 286; 1171l9, 123,
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US3853582A (en) * 1970-02-02 1974-12-10 Raytheon Co Metallized isotropic boron nitride body and method for making same
US3879009A (en) * 1971-08-26 1975-04-22 Gould Inc Mold for making objects
US4416840A (en) * 1981-12-21 1983-11-22 General Electric Company Al2 O3 Ceramic composite
US4778649A (en) * 1986-08-08 1988-10-18 Agency Of Industrial Science And Technology Method of producing composite materials
US5422188A (en) * 1991-05-03 1995-06-06 Societe Nationale D'etude Et De Construction De Moteurs D'aviation "S.N.E.C.M.A." Part made from ceramic composite having a metallic coating, process for producing same and powder composition used
RU2777312C1 (en) * 2021-11-08 2022-08-02 Федеральное государственное бюджетное образовательное учреждение высшего образования "Сибирский государственный университет путей сообщения" (СГУПС) г. Новосибирск Method for metallization of ceramic products

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RU2777312C1 (en) * 2021-11-08 2022-08-02 Федеральное государственное бюджетное образовательное учреждение высшего образования "Сибирский государственный университет путей сообщения" (СГУПС) г. Новосибирск Method for metallization of ceramic products

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