Oxidation Characteristic and Machining Performance of Reaction-Sintered Silicon Carbide Ceramic in Anodically Oxidation-Assisted Polishing

摘要

A novel method for machining reaction-sintered silicon carbide (RS-SiC) ceramic using anodicallyoxidation-assisted polishing is proposed. Through anodic oxidation of RS-SiC, hardness of theoxidized sample can be reduced, and the soft oxide layer is easy to be machined with the assistance ofabrasive polishing. In this way, fine surface quality and high material removal rate can be obtained inmachining RS-SiC. The influences of process conditions on the oxide morphology, oxidation rate, andsurface roughness have been qualitative investigated with scanning electron microscope (SEM) andquantitative analyzed with scanning white light interferometry (SWLI). The results show that anodicoxidation of RS-SiC by phosphoric acid (H3PO4) under the constant potential can obtain soft oxide andsmooth morphology; abrasive polishing of oxide layer can obtain smooth surface with roughness rms8.520nm. Relationship between oxidation depth and its influencing factors can be theoretical analyzedbased on the oxidation mechanism, and the oxidation depth can be calculated by hydrofluoric acid (HF)etching of the oxidized sample. It can be concluded that the anodically oxidation-assisted polishing,which includes the anodic oxidation of RS-SiC by H3PO4 and abrasive polishing of oxide layer byceria slurry, can be treated as a practical method to machine RS-SiC.