Effects of Al2O3-MgO addition on the properties of SiO2-based ceramics prepared by Digital Light Processing

SiO 2 -based ceramics are an ideal material for manufacturing radomes due to their thermal stability, high dielectric properties, and simple processing techniques. However, traditional manufacturing methods heavily rely on molds, making it difficult to form complex SiO 2 -based ceramic structures. Digital Light Processing (DLP) technology was applied to fabricate SiO 2 -based ceramics doped with Al 2 O 3 -MgO in this work. The influence of the Al 2 O 3 -MgO content on the SiO 2 -based ceramics was systematically investigated. Increasing Al 2 O 3 -MgO content causes a shrinkage to first decrease then increase, contrasting with the flexural strength's initial increase and subsequent decrease. The main reason is magnesium-aluminum spinel (MgAl 2 O 4 ) generated during the sintering process and thus retards crack propagation, promoting a transition in fracture mode. During the fracture stage, the fracture mode of samples with 10.0 wt% Al 2 O 3 -MgO is mainly transgranular fracture, instead of intergranular. This transition in fracture mode enhanced the flexural strength. Meanwhile, as the Al 2 O 3 -MgO content continues to increase, excessive spinel causes agglomeration within the ceramic microstructure. When the Al 2 O 3 -MgO content reached 10.0 wt%, the shrinkage decreases to a minimum of 3.32 %, and the flexural strength increases to a maximum of 15.94 MPa, making it suitable for manufacturing ceramic radomes. The research results provide a new solution for manufacturing SiO 2 -based ceramic radomes by DLP.