DIFFUSION COATING PROCESS AND METHOD

• Main Authors: ROSE, BERNARD R, WILLIS, JOHN K
• Format: Patent
• Language: English; French
• Published: 30.10.1993
• Edition: 5
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TOTRANSPORTATION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE

Process for producing novel nickel superalloy bodies having increased resistance of to oxidation and corrosion at high temperatures. The process comprises applying a thin layer of a platinum-group metal and heating to an elevated temperature to diffuse or integrate the platinum-group metal into the surface of the metal superalloy. Then the superalloy body is packed into a container filled with a diffusion powder composition containing sources of aluminum and chromium metals and heated in an inert gas atmosphere to an elevated temperature to codeposit and diffuse aluminum and chromium into the platinum-group metal-treated surface. Finally, the superalloy body is removed from the diffusion coating container and heated to the solvus temperature to form a ductile surface having an outer zone microstructure comprising PtAl2 which has been ductilized by the solutioning of beta chromium. This ductilized PtAl2 may or may not be in a beta phase nickel aluminide matrix depending on substrate composition.