Method of depositing chromium and silicon on a metal to form a diffusion coating
AssigneeThe Ohio State University Research Foundation
InventorsRobert A. Rapp, Ge Wang, Endang Pangestuti
Life of this patent
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Abstract
A method for the simultaneous deposition of chromium and silicon to form a diffusion coating on a workpiece uses a halide-activated cementation pack with a dual halide activator. Elemental metal powders may be employed with the dual activator. A two-step heating schedule prevents blocking a chromium carbide from forming at the surface of the workpiece. Small contents of either Ce or V can be added to the Cr+Si contents of the coating by introducing oxides of Ce or V into the filler of the pack.
Claims13
A method for depositing a chromium and silicon diffusion coating on a metal substrate, comprising:
- (a) placing a cementation pack around a surface of the substrate in an inert atmosphere, the cementation pack including a chromium and a silicon source, at least two activator salts, and a filler;
- (b) heating the substrate and cementation pack in the inert atmosphere to a first temperature of about 925.degree. C. for a time sufficient to deposit silicon on the surface of the substrate;
- and then
- (c) heating the substrate and cementation pack to a second temperature of about 1150.degree. C. for a time sufficient to deposit a diffusion coating of chromium on the surface of the substrate.
A method for depositing a chromium and silicon diffusion coating on a steel substrate, comprising:
- (a) placing a cementation pack around a surface of the steel substrate in an inert atmosphere, the cementation pack including a source of chromium and a source of silicon, at least two halide activators, and a filler including one element selected from the group consisting of Cerium and Vanadium;
- and
- (b) heating the steel substrate and cementation pack to a first temperature of about 925.degree. C. for a time sufficient to deposit silicon on the surface of the substrate and subsequently to a second temperature of about 1150.degree. C. for a time sufficient to deposit a diffusion coating of chromium on the surface of the substrate.
Dependencies are inferred from the claim text.