The hardness properties of porcelain with substitution of quartz by rice husk ash at different soaking time

An extensive studied has been done with rice husk ash (RHA) as a substitute element for quartz to produce porcelain. Rice husk (RH) was treated with HCL. The treated RH was subjected to calcinations at 700 °C for six hours, then subjected to the XRF analysis. The composition of RHA and porcelain powder were mixed using a ball mill for 1.5 hours, then was pressed into pellets at a pressure of 91 MPa. The pellets were sintered at a temperature of 1200 °C for 1 hour, 2 hours and 3 hours soaking time, at a heating rate of 5°C per minute. The bulk density and Vickers hardness were measured. At the soaking time of 2 hours, the maximum density and hardness were achieved at 2.45 g/cm3 and 1052 HV respectively. SEM analysis reveals a typical sequence of densification enhancement with the increasing of soaking time