Ceramics are highly useful materials as frictional materials, because of their high hardness and high heat resistance. This studyanalyzed the elastic wave characteristics in the abrasion test of two types of Si3N4. The friction coefficients of non-coatedceramics with SiO2 nano-colloid were almost similar to that without. However, the friction coefficients of heat-treated ceramicswith SiO2 nano-colloid coating differed, varying with the amount of SiO2 nano-colloid, and the heat treatment temperature. The characteristics of elastic waves generated during friction and wear were similar for the two types of ceramics. The resultsshow that the mechanical properties, such as strength, are determined by the components of the main ceramics in sintering

Keywords: Friction and wear, Friction coefficient, Si3N4 ceramics, SiO2 nano-colloid, Elastic wave