Wear behavior of diamond-silicon nitride composites sintered with FAST/SPS

Diamond-silicon nitride composite materials with 40 vol.% of diamond with two different grain sizes (50 µm and 100 µm) were produced using the field-assisted sintering technique/spark plasma sintering (FAST/SPS). A diamond powder with a SiC coating was also used. For the pure matrix material and the composites, the microstructure and the wear behavior under dry oscillating sliding conditions were investigated with use of steel and silicon nitride balls as counter-body materials. The composite materials showed coefficients of friction (COFs) of as low as 0.1, substantially lower than the COFs (0.8-1.2) obtained for the matrix. The highest wear resistance (wear rate: 8*10-8 mm³/Nm) was observed for the composite material with the SiC-coated diamond particles due to the stronger bonding of the diamond particles to the matrix in this material.