Selective laser sintering of porous Al2O3-based ceramics using both Al2O3 and SiO2 poly-hollow microspheres as raw materials

Porous Al2O3-based ceramics with improved mechanical strength and different pore size were fabricated using Al2O3 and SiO2 poly-hollow microspheres (PHMs) as raw materials by selective laser sintering (SLS). The effects of different contents of SiO2 PHMs on phase compositions, microstructures, mechanical properties and pore size distribution of the prepared ceramics were investigated. It is found that moderate content of SiO2 PHMs (?30 wt %) could work as a sintering additive, which could enhance the bonding necks between Al2O3 PHMs. When the content of SiO2 PHMs increased from 0 wt% to 30 wt%, the compressive strength of Al2O3-based ceramics increased from 0.3 MPa to 4.0 MPa, and the porosity decreased from 77.0% to 65.0% with open pore size decreased from 52.0 ?m to 38.3 ?m. However, SiO2 PHMs could provide pores by keeping its integrity when the content of SiO2 PHMs increased to 40 wt%, which could result in the porosity increasing to 66.8% and pore size decreasing to 30.1 ?m. Selective laser sintering of different kinds of ceramic PHMs is a feasible method to fabricate porous ceramics with complex shape, controllable pore size and improved properties.

Automated summary

The study found that a moderate content of SiO2 PHMs could enhance the compressive strength and reduce the porosity of Al2O3-based ceramics, while increasing the open pore size. However, an increase in the content of SiO2 PHMs to 40 wt% led to an increase in porosity and a decrease in pore size of the material. The selective laser sintering of different types of ceramic PHMs is a feasible method for producing porous ceramics with complex shapes, controllable pore sizes, and improved properties.