Preparation of calcium hexaluminate porous ceramics by gel-casting method with polymethyl methacrylate as pore-forming agent

Calcium hexaluminate (CA6) porous ceramics were prepared by gel-casting method, with α-Al2O3 and CaCO3 as raw materials and polymethyl methacrylate (PMMA) microspheres as pore-forming agent. The effects of the amount of pore-forming agent PMMA microspheres on the phase composition, bulk density, apparent porosity, flexural strength, microstructure, thermal shock stability and thermal conductivity of CA6 porous ceramics were systematically studied. The pores of CA6 porous ceramics are mainly formed by the burning loss of PMMA microspheres and the decomposition of organic matter. Adding an appropriate amount of PMMA microspheres as pore-forming agent has a positive effect on the thermal shock stability of CA6 porous ceramics. When the amount of pore-forming agent is 15 wt%, the volume density of CA6 porous ceramics is 1.33 g/cm3, the porosity is 63%, the flexural strength is 13.9 MPa, the thermal shock times can reach 9 times, and the thermal conductivity is 0.293 W/(m·K), which can meet the application in refractory, ceramics or high temperature cement industries.