Coating for superplastic and quick plastic forming tool and process of using
AssigneeGeneral Motors Corporation
InventorArianna T. Morales
Life of this patent
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Abstract
A coating for superplastic forming (SPF) and quick plastic forming (QPF) tooling and an SPF/QPF process made possible with the coating. The coating defines the forming surface of an SPF/QPF tool, and consists essentially of either a tungsten carbide cermet or a chromium carbide cermet. The coating preferably comprises a metal matrix containing tungsten carbide or chromium carbide particles having a particle size of not more than 0.1 micrometer, and is preferably prepared to have a surface finish of not rougher than 0.3 micrometer Ra. An SPF/QPF process that makes use of a tool whose forming surface is provided with the coating can be performed without depositing any lubricant on the forming surface or workpiece.
Claims26
A superplastic forming tool comprising a coating on a surface thereof, the surface having a surface finish of not rougher than 0.5 micrometer Ra, the coating covering the surface to define a forming surface of the tool, the coating consisting essentially of either a tungsten carbide cermet or a chromium carbide cermet, the coating having a surface finish of not rougher than 0.3 micrometer Ra.
A superplastic forming tool comprising an external coating on a surface thereof, the surface having a surface finish of not rougher than 0.5 micrometer Ra, the coating covering the surface to define a forming surface of the tool, the coating having a surface finish of about 0.2 to about 0.3 micrometer Ra and a thickness of less than 0.2 millimeter, the coating consisting of a cermet material containing tungsten carbide particles in a cobalt matrix or chromium carbide particles in a nickel-chromium alloy matrix, the particles having a particle size of not more than 0.1 micrometer.
A superplastic forming process comprising the steps of:
- polishing a surface of a forming tool to have a surface finish of not rougher than 0.5 micrometer Ra;
- providing a coating on the surface of the forming tool, the coating consisting essentially of either a tungsten carbide cermet or a chromium carbide cermet;
- polishing the coating to define a forming surface having a surface finish of not rougher than 0.3 micrometer Ra;
- and
- without depositing a lubricant on the forming surface, superplastically forming a workpiece on the forming surface of the forming tool.
A superplastic forming process comprising the steps of:
- polishing a surface of a ferrous forming tool to have a surface finish of not rougher than 0.5 micrometer Ra;
- depositing a coating on the surface to a thickness of about 0.18 to 0.23 millimeters micrometer, the coating consisting essentially of either a tungsten carbide cermet or a chromium carbide cermet;
- polishing the coating to define a forming surface having a surface finish of about 0.2 to 0.3 micrometer Ra and a thickness of about 150 micrometers;
- and then
- superplastically forming a workpiece on the forming surface of the forming tool.
Dependencies are inferred from the claim text.