This paper describes microstructure control aimed for wear-resistance improvement of Co-based (Co-Cr-W-B-Si) self-fluxing alloy coating by diffusion treatment. The diffusion treatments of thermally sprayed Co-based self-fluxing alloy coating on steel substrate were carried out at 1370K to 1450K for 600s to 6000s under an Ar gas atmosphere. Microstructural variations of the coating and the interface between the substrate and the coating were investigated in detail. A proper diffusion treatment precipitates two kinds of fine compounds in Co-based matrix. XRD and EPMA analysis revealed these precipitates to be a chromium boride dissolving cobalt and a wolfram boride containing cobalt and chromium. The size of each precipitate became larger with increasing treatment temperature and time. A coating with the proper size borides showed a superior wear-resistance.

cobalt-chromium-tungsten alloys, diffusion, electron probe X-ray microanalysis, microstructure, self-fluxing alloys, thermal spraying, wear resistance, X-ray diffraction
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Copyright © 2007 ASM International. All rights reserved.
2007
ASM International
Topics
Microstructure Cobalt-chromium-tungsten alloys Thermal spray coating Electron probe X-ray microanalysis Wear resistance X-ray diffraction
Issue Section:
Surface and Coating Treatments
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