Microstructural and mechanical characteristic of ceramic composite coating developed by electrophoretic deposition

Ceramic-composite coating consisted of Yttria Stabilized Zirconia (YSZ), Fe2O3 and aluminum powder has been successfully formed on Inconel 625 substrate by electrophoretic deposition (EPD). The coating density depends not only on the stability of the EPD suspension but also on the applied voltage. In the present study, a single stage voltage treatment at 60V and a two-stage voltage treatment at 30V followed by 60V of the EPD were used. A fresh green body of ceramic coating was dried at room temperature for 24 hours prior to heat-treated at temperature of 1200 °C for 4 hours with heating rate of 2°C/min using horizontal heated furnace under argon gas inert. The effect of single- and two-stage treatments on the microstructural and mechanical hardness of the coating were investigated by Field Emission-Scanning Electron Microscopy and Vickers hardness test, respectively. The elemental composition of the coating was analysed by Energy Dispersive Spectroscopy and the crystalline phases were identified by x-ray diffractometer. The results showed that a less porous structure, and therefore, higher hardness was observed on the coating formed by a two-stage voltage than that of resulting from a single-stage voltage. The crystalline phase formed on the coatings was dominated by a tetragonal phase of ZrO2.