Effect of cobalt oxide additive on the fired properties of tri-axial ceramic

Fired properties of a tri-axial ceramic system were studied in presence of 1–5 wt% cobalt oxide (CoO) additive as a function of firing temperatures in the range of 1100–1300 °C. The results showed significant improvement in physical and mechanical properties of the batches in presence of 1% CoO additive compared to that of batches without additive in the firing temperature range of 1100–1200 °C. Phase analysis showed that 1% CoO additive improved melting of feldspar and enhanced mullitization. Microstructural analysis confirmed that the morphology of the mullite crystals changed significantly in presence of additive at lower temperature. 1% CoO here acted as a good additive and helped to achieve optimum fired properties at a comparatively lower temperature. Except at 1100 °C fired batch, the presence of higher quantum of additive (5%) rather deteriorated the material properties.