Effects of particle grading on properties of silica ceramics prepared by selective laser sintering

Abstract

It is difficult to prepare ceramic cores by traditional technology due to high dependence on mold and the difficulty of manufacturing complex structures. Additive manufacturing technology can solve these problems. In this study, the silica ceramics were prepared by selective laser sintering (SLS) based on particle grading. Adding appropriate amount of fine powder to coarse powder could improve the mechanical properties of silica ceramics. As a result, the flexural strength of silica green bodies reached a maximum of 3.20 MPa when the mass ratio of coarse powder (D 50 = 45.6 μm) and fine powder (D 50 = 23.3 μm) was 4:5. With the increase of fine powder content, the shrinkage and flexural strength of silica ceramics first increased and then decreased, while the apparent porosity showed an opposite trend. When the mass ratio was 4:5, the maximum of flexural strength was 7.15 MPa with the linear shrinkage of 4.76% and the apparent porosity of 47.28%. Compared with silica ceramics without fine powder, the flexural strength of silica ceramics increased by nearly 550% (from 1.13 MPa to 7.15 MPa) under the optimal particle grading. Therefore, the silica ceramics with good mechanical properties were prepared by SLS via optimizing the particle grading.