Preparation and properties of reticulated porous γ-Y2Si2O7 ceramics with high porosity and relatively high strength

Dense γ-Y2Si2O7 ceramics are promising silicates with very low thermal conductivity, good damage tolerance and hot corrosion resistance. However, processing of porous γ-Y2Si2O7 was not reported in early literatures. In this paper, reticulated porous γ-Y2Si2O7 ceramics with high porosity (~85%) and relatively high compressive strength (~1.28 MPa) are successfully fabricated by the polymeric sponge impregnation method. The main compositions of the slurry are Y2SiO5 and silica sol. Samples are sintered at the temperature of 1550 °C to obtain porous γ-Y2Si2O7 ceramics by reaction bonding; and the samples are recoated 3 times to enhance the compressive strength of porous ceramics. Scanning electron microscopy and X-ray tomography investigations show that the pore size distribution of the as-prepared porous γ-Y2Si2O7 ceramic ranges from 200 to 700 μm; meanwhile, the sample possesses fully open and highly interconnected pores. Influences of pretreatments of sponge on the compressive strengths of samples are also investigated. This work reports a new porous ceramic material (γ-Y2Si2O7) with high permeability, high strength and controllable macrostructure.