Tribological characterisation of siliconcarbonitride ceramics derived from preceramic polymers

Amorphous SiCN ceramics were prepared in a laboratory scale as disk shaped specimens with 10 mm diameter and 0.3 mm thickness. The friction and wear behaviour was characterised in gross slip fretting tests under unlubricated conditions at room temperature against steel (100Cr6) and ceramic (Al2O3). Tests with a ball-on-disk contact were performed in laboratory air with different content of water vapour. The results show clearly that the relative humidity has a significant effect on friction and wear behaviour. All tests in dry air lead to higher friction and higher wear rate than in normal air. Improved friction and wear behaviour was observed with increasing pyrolysis temperature up to 1100 °C of the SiCN specimens. This is attributed to increasingly better mechanical properties and higher stiffness of the amorphous network due to the evaporation of gaseous organic species and the formation of free graphite like carbon.