Effect of Fused Silica Powder Content on the Properties of MgO-Based Ceramic Core
The effects of the mineralizer(fused silica powder)content on the phase composition,microstructure,sintering shrinkage,apparent porosity,linear thermal expansion coefficient,room temperature and high temperature flexural strength,and leaching rate of magnesia-based ceramic cores were studied by means of X-ray diffraction,scanning electron microscopy(SEM)and energy dispersive spectrometry(EDS).The results show that with the increasing of fused silica powder content,the content of magnesium silicate increases,the ceramic matrix particles are refined,and the connected large pores are transformed into closed small pores.The bonding between the particles is loose,and the removal performance and flexural strength are greatly reduced.The MgO-based ceramic core obtained by adding 30%SiO2 has the best comprehensive performance.The sintering shrinkage rate is 2.8%,the apparent porosity is 32.9%,and the flexural strength at room temperature is 15.1 MPa.The leaching rate of the core is 61.9%when leached in 40%CH3COOH aqueous solution for 120 h.
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