Scaning electron microscopy and roughness measurements of the wear scars generated in carbide composites

摘要

Fig. 17 shows typical microstructures--at very different magnifications--of the two types of carbide microstructure used in this study. The first group (Fig. 17a) consisted of WC/Co cemented carbides with coarse carbide grain size in the range 2.5 to 15 urn and cobalt binder content from 6 to 11 wt. percent. Hardness was between 970 and 1500 HV. The DC carbides (Fig. 17b) were composites of spherical sintered WC/Co granules dispersed in a cobalt or high-cobalt alloy matrix. Two DC carbides were selected; one with 50 um WC/Co pellets (92 HRA) in a cobalt alloy matrix (33 vol. percent) and the other with similar composition but with a 10 vol. percent addition of 1.5 um WC particles to the matrix. Overall hardness of the DC composites was about 84 HRA and density about 12.4 g/ml~3.