Spark assisted chemical engraving (SACE) mechanism on ZrO2 ceramics by analyzing processed products

Traditional machining processes are usually unworkable for ZrO2 ceramics due to the mechanical properties of fragility, high hardness and high-temperature resistance. The process of spark assisted chemical engraving (SACE) has been explored for machining ZrO2 ceramics, but up to now the processing mechanism has not been clearly understood yet. To understand the microscopic mechanism, the phase transition paths of ZrO2 ceramics under various physical and chemical conditions were analyzed. A backstepping approach based on structures and components of SACE processed products was proposed to verify the physical and chemical mechanisms. According to the crystal phase composition of the processed debris resulting from Raman spectrum analysis, it was found that the debris exhibited crystalline and amorphous forms which provided the evidence of physical crushing and chemical reactions. Furthermore, the chemical removal mechanism was proven by the nearly saturated concentration of Zr ion in the processed solution according to the ICP-OES assay of SACE electrolyte. The quantitative proportion of physical and chemical effect can be successfully determined by distinguishing and analyzing two kinds of debris with different crystal phase compositions which yield distinctly identifiable appearances under an optical microscope.