Methods of applying chromium diffusion coatings onto selective regions of a component
AssigneePraxair S.T. Technology, Inc.
InventorsZhihong Tang, Kevin E. Garing, Thomas D. Findlay, Thomas F. Lewis, III, James K. Knapp
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Abstract
Unique and improved chromizing processes are disclosed. The processes involve forming localized chromizing coatings onto selected regions of a substrate. The chromium diffusion coatings are locally applied to selected regions of substrates in a controlled manner, in comparison to conventional chromizing processes, and further in a manner that produces less material waste and does not require masking. A second coating can be selectively applied onto other regions of the substrate.
Claims16
A method for producing a chromium diffusion coating onto selected regions of a substrate, comprising the steps of:
- providing a chromium-containing slurry;
- applying the chromium-containing slurry onto localized surfaces of the substrate;
- curing the slurry;
- heating the slurry in a protective atmosphere to a predetermined temperature for a predetermined duration;
- generating chromium-containing vapors;
- diffusing the chromium into said localized surfaces to form the coating, said coating having a microstructure characterized by a substantial reduction in nitride and oxide inclusions and reduced levels of α-Cr phase in comparison to conventional chromizing processes.
A method for producing a localized chromium diffusion coating and a localized aluminide diffusion coating onto selected regions of a substrate simultaneously, comprising the steps of:
- providing a chromium-containing slurry;
- applying the chromium-containing slurry onto a first region of the substrate, characterized by an absence of masking;
- providing an aluminide-containing material;
- heating the chromium-containing slurry and the aluminide-containing material in a protective atmosphere to a predetermined temperature for a predetermined duration;
- diffusing chromium into the first region;
- diffusing aluminum into a second region in the absence of masking;
- forming the localized chromium diffusion coating along the first region, said chromium diffusion coating having a microstructure characterized by a substantial reduction in nitride and oxide inclusions and reduced levels of α-Cr phase in comparison to conventional chromizing processes;
- and
- forming a localized aluminide-diffusion coating along the second region.
A method for producing a localized chromium diffusion coating and a localized aluminide diffusion coating onto selected regions of a blade simultaneously, comprising the steps of:
- providing a chromium-containing slurry;
- applying the chromium-containing slurry onto a shank of the blade, characterized by an absence of masking;
- providing aluminide-containing material within the retort;
- loading the partially coated blade into the retort;
- heating the partially coated blade;
- generating aluminum containing vapors and chromium containing vapors;
- diffusing chromium from the chromium-containing vapors into an external region of the shank of the blade;
- diffusing aluminum from the aluminum-containing vapors into an airfoil of the blade;
- forming the localized chromium diffusion coating along the shank, said chromium diffusion coating having a microstructure characterized by a substantial reduction in nitride and oxide inclusions and reduced levels of α-Cr phase in comparison to conventional chromizing processes;
- and
- forming the localized aluminide-diffusion coating along the airfoil.
Dependencies are inferred from the claim text.