Indentation Load Effect on Young's Modulus and Hardness ofPorous Sialon Ceramic by Depth Sensing Indentation Tests

Abstract

Depth sensing indentation (DSI) tests at the range of 200–1800 mN areperformed on porous sialon ceramic to determine the indentation load onYoung's modulus and hardness values. The Young modulus and hardness(Dynamic and Martens) values are deduced by analysing the unloadingsegments of the DSI test load-displacement curves using theOliver–Pharr method. It is found that Young's modulus Er,the dynamic hardness HD and the Martens hardness HM exhibitsignificant indentation load dependences. The values of Young's modulusand hardness decrease with the increasing indentation load, as a resultof indentation load effect. The experimental hf/hm ratios lower thanthe critical value 0.7, with hm being the maximum penetration depthduring loading and hf the final unloading depth, indicate that oursample shows the work hardening behaviour.