Micro-shot peening of zirconia-advanced ceramic: An examination of surface integrity

This paper presents the micro-shot peening of zirconia (ZrO₂)-advanced ceramics applicable for bio-medical, dental, automotive and aerospace sectors. A ZrO₂-advanced ceramic was micro-shot blasted with selected parameters as a first-step investigation focused on the topography, microstructure, surface hardness and the surface fracture toughness (K_Ic) characteristics. A new technique of micro-blasting was conducted using a portable shot blaster. A white-light interferometer, scanning electron microscopy and Vickers indentation technique were employed for the analysis. This was followed by determining the K_Ic using an empirical equation. Surface roughness was improved by 34 % after micro-shot blasting treatment. No surface cracking was present which generally exists due to the brittle nature of the ceramic. The hardness, however, reduced by 5.6 % with a reduction in the Vickers crack length of 9 %. This improved the K_Ic by 3 % when comparing the micro-shot peened surface to the original, as-received surface. It is difficult to conclude if the ZrO₂-advanced ceramic has undergone plastic deformation and the movement of dislocations increased to strengthen the ZrO₂ ceramic at this stage. However, based on the results, it can be predicted that a level of surface compression was induced beneath the micro-shot peened layer as indicated from the result of the surface topography and integrity. This would justify the hardness modification and the enhancement in K_Ic.