Indirect forming of alumina-based ceramics by selective laser sintering combined with sol infiltration process and performance study

摘要

Abstract Aluminum-based ceramic cores have been widely used in the manufacture of aero-engine hollow blades because of their excellent chemical stability, stable high-temperature properties and mechanical properties. In this study, in order to prepare alumina-based ceramic cores with stable strength, high apparent porosity and low sintering shrinkage, ceramic greens with predominantly irregular polyhedral alumina powder particles were successfully prepared using selective laser sintering technique. Subsequently, sol infiltration process was used to improve the mechanical properties of alumina-based ceramics, and the effects of nanoalumina sol and silica sol infiltration on the micromorphology and mechanical properties of ceramic bodies were studied. The results showed that the green bodies contained more holes when the incubation space and printed layer thickness were determined with a scanning speed and laser power of 2300 mm/s and 30 W, respectively. After infiltration of nanosilica sol, the apparent porosity of alumina-based ceramics decreased from 44.7 to 35.3, and the ultimate compressive strength increased from 32.5 MPa to 78.8 MPa. After three cycles of infiltration, the compressive strength of the samples reached 117.2 MPa and the flexural strength reached 12.6 MPa. These are caused by the reaction of silica nanoparticles with alumina ceramic bodies at 1300 °C to form mullite and α-cristobalite phases.