Effect of Mould Pressure and Substitution of Quartz by Rice Husk Ash on the Bulk Density and Compressive Strength of Porcelain Body

RHA has become an important competitive material for preparation of silicon compounds due to high surface area, high grade of amorphous form silica and fine particle sizes. The effect of mould pressure (MP) and substitution of quartz by RHA on bulk density and compressive strength of porcelain body is investigated. RHA is used as a substitute for quartz with different replacement levels (0 wt% - 25 wt%). The samples are pressed into pellets at a mould pressure of 31 MPa, 61 MPa, 91 MPa and 121 MPa. All the pellets are sintered at the temperature of 1200 °C for 2 hours soaking time and at a heating rate of 5 °C per minute. The bulk density and compressive strength are measured at the highest value of 2.42 g/cm3 and 39 MPa for the sample pressed at 91 MPa with the substitution of 20 wt% RHA. The improvement in the properties could be attributed to the sharp changes in the microstructural features as a result of an increase in mullite and glassy phase simultaneously.