Co-deposition and densification of SiC with MgO for biomedical applications

This article focuses on the electrophoretic co-deposition of SiC and MgO, which has not been previously reported. The EPD of SiC has been widely investigated, whilst the EPD of SiC with sintering additives is usually not taken into account since every compound added to the suspension seriously affects the zeta-potential and the conductivity, the two main parameters that should be optimized to achieve a good deposit. We comprehensively observed the effects of the individual compounds on the colloidal behaviour of a suspension suitable for co-deposition to achieve good homogeneity and the highest possible green density. The obtained green densities reached up to 1.92 g/cm³, which correspond to 60% of theoretical density, whilst after sintering in open air at 1350 °C the densities reached 2.33 g/cm³. SEM and TEM analyses revealed that the microstructure is composed of SiC grains embedded in a SiO₂ matrix, whilst XRD confirmed that even though the sintering caused a partial oxidation and the appearance of an amorphous phase, the prevailing crystalline phase is still β-SiC. In the presence of MgO, SiO₂ also appears in the crystalline form as cristobalite.