Electrochemical oxidation and corrosion behavior of 3D printed reaction-bonded silicon carbide ceramics in eco-friendly electrolyte

Abstract

3D printed reaction-bonded silicon carbide (RBSiC) is widely employed across various industries due to its complex geometries and exceptional properties. However, its precise machining remains a significant challenge. Electrochemical grinding (ECG) presents a promising solution for the precise machining of RBSiC. Still, further optimization of the process is still required. In this study, we investigate the electrochemical oxidation and corrosion behavior of 3D printed RBSiC in an eco-friendly KH₂PO₄ electrolyte, characterize its microstructure and phases composition, and developed a predictive model for the thickness of the oxidation layer. Experimental results show that the oxidation process of RBSiC, influenced by free silicon, is intricate and segmented, involving the oxidation of Si and SiC as well as Si over-passivation under high voltage. SEM reveals that the oxide film thickness ranges from 1.57 μm to 15.5 μm. EIS and microstructural analysis identify micro defects filled with electrolyte in the oxide layer at high voltage, causing the dielectric constant to surge to 19.65—a nearly 500 % increase. Thus, this study calibrates oxidation current efficiency (η) and the real dielectric constant (${\epsilon }_{ra}$) of RBSiC in KH₂PO₄ electrolyte, leading to the development of a three-stage predictive model that matching with the observed oxide film growth trends. These findings provide a theoretical framework and empirical data for optimizing ECG processing of RBSiC.