Control of the Cobalt Surface Layer Formation on Cemented Carbides

The formation of a surface layer of cobalt on cemented carbides which occurs on cooling during sintering is an often observed phenomenon which has been discussed in the recent literature. The presented work shows different factors which influence the formation of the layer and proposes factor-related mechanisms. For this purpose cemented carbide samples with different compositions, WC grain sizes and carbon contents were produced and studied. The results reveal that besides the cooling conditions also the variations in composition and microstructure of the material play an essential role for the formation of a surface layer.