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US 3,962,490 AGranted
Preparation of nickel and chromium substrates for ceramic coating
AssigneeFerro Corporation
InventorRodney L. Ward
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AssigneeFerro Corporation
InventorRodney L. Ward
Estimating the term…
A process and product are disclosed relating to the preparation of a metallic substrate of a workpiece for a subsequent deposition of a ceramic coating, such as porcelain enamel, in which the metal of the substrate is one that is not sufficiently electrochemically active to be coated by electrophoresis, for example, stainless steel or those alloys containing principally nickel and/or chromium. In one form, the metallic substrate is first covered with an oxide, and preferably a thermally decomposable compound, of a transition metal selected from Groups IIIB through Group IIB of the Periodic Table of The Elements. The workpiece is then heated to alloy the transition metal with the substrate of the workpiece, after which a ceramic coat may be applied. When the transition metal is present as a thermally decomposable compound, the compound must decompose prior to reaching an alloying temperature.
In the process of depositing a frit composition on a substrate and then heating to form a ceramic coat from the frit composition, the improvement prior to depositing said frit composition comprising using as the substrate a metallic workpiece that is not sufficiently electrochemically active to be coated by electrophoresis and that contains at least 10% by weight of a metal selected from nickel, chromium, and mixtures thereof, covering at least a portion of said substrate with a film of an oxide or a thermally decomposable compound of a transition metal selected from Group IIIB through Group IIB of the Periodic Table of The Elements, said compound being thermally decomposable at a temperature below the alloying temperature of the workpiece and transition metal, and then heating the workpiece to an alloying temperature within the range of about 1000.degree.F to about 1800.degree.F to alloy the transitional metal therewith.
A process for preparing a metallic workpiece having a substrate that is not sufficiently electrochemically active to be coated by electrophoresis and that contains at least 10% by weight of a metal selected from nickel, chromium, and mixtures thereof for deposition thereon of a ceramic coat, comprising contacting said substrate with an aqueous solution of a thermally decomposable, water soluble compound of a transition metal selected from Group IIIB through Group IIB of the Periodic Table of The Elements to deposit thereon a film of the compound, heating the workpiece to thermally decompose said compound below an alloying temperature of the workpiece, and then heating the workpiece to an alloying temperature within the range of about 1000.degree.F to about 1800.degree.F to alloy the transition metal of said compound with the substrate.
A process for preparing a workpiece having a metallic substrate that is not sufficiently electrochemically active to be coated by electrophoresis for a subsequent deposition of a ceramic coating, said substrate containing at least 10% by weight of a metal selected from nickel, chromium, and mixtures thereof, comprising covering at least a portion of said substrate with a film of an oxide or a compound of a transition metal selected from Groups IIIB through Group IIB of the Periodic Table of The Elements, said transitional metal compound being thermally decomposable at a temperature below an alloying temperature of the workpiece and transition metal, heating the workpiece below such alloying temperature to thermally decompose said compound, depositing ceramic particles onto the treated substrate of the workpiece, and then firing the workpiece to provide a ceramic coat from said particles on the workpiece, at least one of said heating and firing steps also including heating to an alloying temperature within the range of about 1000.degree.F to about 1800.degree.F to alloy said transition metal with said substrate of the workpiece.
Dependencies are inferred from the claim text.