Chiang Mai Journal of Science

Cylindrical graphite was coated with silicon carbide to improve the oxidation resistance at elevated temperature. This protective layer was obtained by sintering of a Si layer using a furnace with argon atmosphere at 1,450°C for 20 min. This Si layer had been coated on to graphite via DC-Electrophoretic Deposition (DCEPD). The aim of the present work is an investigation on silicon deposition behavior during the EPD on graphite. The EPD experiments were performed at different deposition voltage and time using Ethanol-based suspension stabilized with Dolapix ET 85. The results suggest that if EPD is performed at 50V for 20 min, a uniform and crack-free deposit is obtained. Increasing deposition voltage and time more than optimum resulted in the detachment of the deposit layer due to increased deposit layer weight and greater liquid turbulence. The phase composition, surface microstructures of the deposit and sintered coating were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).