Cobalt tungsten carbide mixture

Thermal spray processes can be used to give coatings of chromium carbide or nickel chromium for erosion resistance, copper nickel indium for fretting resistance, tungsten carbide cobalt for wear and abrasion resistance, and even aluminum siHcon polyester mixtures for abradabiHty. 

Mixtures of powders of two materials sinter very rapidly if one of them melts at the sintering temperature. Initially capillary action causes the liquid phase to rapidly wet the solid phase, causing an initial contraction. Then as the solid phase dissolves in the liquid it is rapidly transported to locations that decrease the pore volume. Carbide tool material is made from a mixture of cobalt and tungsten carbide powders sintered below the melting point of cobalt. The volume fraction liquid must be limited so capillarity can retain the shape during sintering. 

The most important property of tungsten carbide in its utilization in cemented carbides is its ability to dissolve partially in compressed powder mixtures of WC and ferrous metals, particularly cobalt, at 1300 to 1500°C. In the case of sintering with a liquid phase, WC partly crystallizes out of the binder phase of the WC-Co-alloy upon cooling. It becomes embedded in the tough but hard (not brittle) binder phase. 

Physical Description A mixture of tungsten carbide, cobalt, and sometimes other metals metal oxides or carbides. 

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