Development of Carbide Dispersed High Heat and Wear Resistant Sintered Material

Abstract

Conventionally, high Cr cast steel having excellent oxidation resistance and wear resistance has been used for the heat resistant bearing of the turbocharger. In recent years, the usage environment has become more and more severe, and bearing materials are required to have higher wear resistance and oxidation resistance. Therefore, we have developed high heat resistant sintered material that is superior in wear resistance and oxidation resistance to high Cr cast steel in high temperature environment. In microstructure of the developed material, particulate fine carbides are dispersed in the matrix of densified ferritic high Cr steel. The feature of the developed material is that it has excellent wear resistance by dispersing about twice as much carbide as high Cr cast steel. Another feature is that the shape of the carbide is granular in order to minimize the decrease in oxidation resistance. In addition, the developed material is densified by liquid phase sintering to suppress the progress of internal oxidation. Despite the large amount of carbide dispersed in the developed material, it has become possible to achieve higher oxidation resistance than conventional high Cr cast steel.