Thermomechanical coupling effect on characteristics of oxide film during ultrasonic vibration-assisted ELID grinding ZTA ceramics

Ultrasonic vibration-assisted ELID (UVA-ELID) grinding is utilized as a novel and highly efficient processing method for hard and brittle materials such as ceramics. In this study, the UVA-ELID grinding ZTA ceramics is employed to investigate the influence of thermomechanical loading on the characteristics of oxide film. Based on the fracture mechanics of material, the model of internal stress for oxide film damage is proposed. The thermomechanical loading is composed of mechanical force and the thermal stress generating from grinding temperature. The theoretical model is established for the mechanical force, thermal stress and internal stress respectively. Then the finite element analysis method is used to simulate the theoretical model. The mechanical force and grinding temperature is measured during the actual grinding test. During the grinding process, the effect of grinding wheel speed and grinding depth on the thermomechanical force and the characteristics of oxide film is analyzed. Compared with the conventional ELID (C-ELID) grinding, the mechanical force decreased by 25.6% and 22.4% with the increase of grinding wheel speed and grinding depth respectively, and the grinding temperature declined by 10.7% and 12.8% during the UVA-ELID grinding. The thermal stress in the latter decreased by 16.3% and 20.8% respectively, and internal stress reduced by 12.3% and 15.6%. It was experimentally found that the topographies of oxide layer on the surface of the wheel and the machined surface in the latter was better than that in the former. The results indicate that the action of ultrasonic vibration establish a significant effect on the processing. Subsequently, it should be well considered for future reference when processing the ZTA ceramics.