Regulation of sintering procedure on property of DLP-printing SiO₂–Al₂O₃ ceramic: Key of cristobalite precipitation

In this work, alumina was selected as the second phase reinforced fused quartz ceramics and SiO₂–Al₂O₃ composite ceramics were fabricated via digital light processing (DLP) 3D-printing. The effect of the sintering procedure on the mechanical and dielectric properties of SiO₂–Al₂O₃ composite ceramics were investigated in detail. The results show that the amount of cristobalite precipitation is the key factor affecting the properties of composite ceramics. The amount of cristobalite precipitation in composite ceramics could be controlled effectively by adjusting the heating rate, holding time, and sintering temperature. The sintering procedure is set as the heating rate of 4°C/min, sintering temperature of 1200°C, and holding time for 2 h, the flexural strength of SiO₂–Al₂O₃ composite ceramic is 47.13 MPa, dielectric constant ranges from 2.90 to 2.97, and the tangent of loss angle is less than 0.041. SiO₂–Al₂O₃ composite ceramics with high flexural strength and low dielectric constant were obtained by sintering procedure screening and optimization.