Material removal behavior in scratching of zirconia ceramic surface treated with laser thermal shock

Abstract

Laser thermal shock (LTS)-assisted grinding is a novel technology for processing ceramics. However, the material removal mechanism in LTS-assisted grinding has not been studied extensively, hindering the sufficient development of its potential. This paper focuses on the material removal mechanism in LTS-assisted grinding by investigating the material removal behavior in LTS-assisted scratching of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). In order to reveal the different material removal behaviors between the Y-TZP specimen surfaces with and without LTS, the scratch characteristics were investigated and compared in terms of hardness of the ceramic surface, scratching force ratio (SFR), and scratch morphology. Compared with the surface without LTS, the grooves on the surface with LTS were deeper, the SFR was larger, and the hardness of surface decreased. These results indicate that the grindability of Y-TZP significantly improved from the assistance of the LTS. As further evidence, prominent marks of grain spalling were found in the scratch grooves on the surface with LTS and the material removal volume increased. These results indicate that the cutting efficiency of the tool improved after the surface was treated with LTS. Furthermore, the plastic ridges and marks of grain spalling on the surface assisted with LTS indicate the existence of ductile-brittle mixed mode. This is significant and beneficial for ceramics grinding due to its improved surface integrity and large material removal rate.