Fabrication of Al2O3‐SiO2 ceramics through combined selective laser sintering and SiO2‐sol infiltration

Abstract

AbstractIn this study, different posttreatment methods, including silica‐sol infiltration (SI), vacuum silica‐sol infiltration (vSI), debinding (DB), and pressure‐less sintering (PS), were combined with selective laser sintering (SLS) to fabricate Al2O3‐SiO2 ceramics. The macro‐morphology and microstructure of sample fabricated under different laser processing parameters and posttreatment process were investigated. Results show that the geometric dimension accuracy and surface quality of the final samples can be effectively improved with appropriate SLS parameters and posttreatment. The optimal SLS processing parameters are determined to be 0.15 mm, 10 W, 0.1 mm, and 1500 mm/s for the hatch spacing, laser power, layer thickness, and scanning speed, respectively. The SLS/DB/vIN/FS samples have the smallest linear shrinkage ratio (<1%), the least warpage degree (<3%), and the best surface quality (surface altitude difference <170 μm). Mullite, quartz, corundum, and cristobalite composed the phases of the sample, of which cristobalite came largely from the infiltrated silica‐sol. Since a higher amount of silica‐sol infiltrated into the sample under SLS/DB/vIN/FS process, more cristobalite phase formed in the pore of the sample during sintering, which avoided excessive microstructure shrinkage during sintering and ensured the high geometric accuracy and surface quality of the final sample.