Tribological properties of SiC-B4C ceramics under dry sliding condition

Abstract

SiC-B4C ceramic composites with different ratios of SiC to B4C were produced. The relative density, mechanical properties, initial surface characteristics, dry sliding tribological properties against SiC ball and worn surface characteristics of the SiC-B4C ceramics were studied. Results of dry sliding tribological tests showed that, 40 wt. % SiC-60 wt. % B4C ceramic composite had the best tribological properties in SiC-B4C ceramic composites. A relief structure with height difference of 10−30 nm between B4C grains and SiC grains is formed after dry sliding. This relief structure, on the one hand, can reduce real contact area on interface, decreasing adhesion effect, and on the other hand, can fix or trap the wear pieces formed on sliding interface during the dry sliding process, reducing the abrasive wear. However, there is a limit to the beneficial influence of decreased adhesion effect and reduced abrasive wear, and an optimum proportion of relief structure. Pores can also fix or trap some wear pieces, reducing the abrasive wear. Under the condition of strong bonding between SiC grains and B4C grains, the SiC-B4C ceramic composites with higher porosity can obtain better tribological properties. In addition, it is observed by AFM that the depth of scratch on B4C grains is shallower than that on SiC grains. Hence, it is demonstrated by micro scale measurement that the wear rate of B4C is lower than that of SiC in this study.