Indentation Size Effect on the Hardness of Silicon Carbide Ceramics

Abstract

The Vickers hardness of CVD SiC ceramics is determined as a function of the indentation load. Vickers hardness pyramid-shaped sharp diamond indenter with angle between opposite faces at an angle of 136° was used to apply five indentation loads of 4.91; 9.81; 29.43; 49.05 and 98.1 N. Care was taken to make indentations only on those areas which had no visible pores. The load was applied at ambient room temperature and dwell time of 15 s. At each indentation load level, 30 perfect indentation were made for CVD SiC ceramics.The results show that the measured hardness depends crucially on the load, which indicates the influence of the indentation size effect (ISE). The load dependence of hardness is analyzed by using the traditional Meyer Law; a proportional specimen resistance (PSR) model and a modified proportional specimen resistance (MPSR) model. The best correlation between measured values and used models is achieved by using the Meyer Law and the modified PSR model. The Meyer index n obtained experimentally is less than 2 (1.7728), which indicates that hardness is dependent on test loads.

Keywords

• Silicon Carbide Ceramics