LAUSR

ZrO2 ceramic has a wide range of applications, such as in the thermal barrier coating (TBC) of turbine blades, micro actuators, and gas sensors. However, this material is challenging to machine due to its high hardness and brittleness. Although spark assisted chemical engraving (SACE) can be used to machine ZrO2 ceramics, the traditional SACE models for glass are difficult to apply to ZrO2 ceramics since the melting point of ZrO2 is much higher than that of glass. A theoretical basis for applying the SACE process to ZrO2 ceramics is still lacking, which makes applying the SACE process to machine micro cavities with high surface quality in ZrO2 ceramics very challenging. This paper proposes an energy action model based on the processing voltage, pulse width and machining gap by analyzing the energy transfer process of SACE. The energy model expresses difference in the spark energy between physical removal and chemical removal. Through machining experiments, the contact effect of the SACE process on ZrO2 ceramics was found, and the reasons why the SACE process is sensitive to the machining gap were clarified. Furthermore, physical and chemical removal process models with or without the discharge constraint onto the end of the tool electrode were established. Using the above theoretical models, a circular ring microcavity without micro cracks on surface was achieved in a ZrO2 ceramic workpiece by using the SACE process with the regulating energy effect trending to the chemical removal. Additionally, considering the contact effect and the process models applied in the SACE scanning process of ZrO2 ceramics, a tool electrode with a spring structure was employed to solve the bending problem of the micro tool electrode. As a result, a square micro-cavity with high surface quality was machined successfully.