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Porous anorthite/mullite composite ceramics with different mullite contents were fabricated by foam―gelcasting method, using CaCO₃, SiO₂, α―Al₂O₃ as raw materials. Effects of mullite content on bulk density, porosity, compressive strength, thermal conductivity and microstructure of the porous composite ceramics were researched. Mullite content has great effect on the apparent porosity of the porous anorthite/mullite composite ceramics. As a result of the appearance of liquid phase in the sintering, the sample shrunk, which is the main reason for the porosity decrease. Compressive strength and thermal conductivity increase with the mullite content under the condition of the similar porosity. Dense pore wall and rod―like mullite grain are benefit for compressive strength of porous anorthite/mullite composite ceramics. The apparent porosity of the prepared porous anorthite/mullite composite ceramics is in the range of 60.8%―75.2%, the compressive strength is between 12.94 MPa and 36.95 MPa, and the thermal conductivity is in the range of 0.30―1.33 W/(m·K)

ZrB 2 (zirconium diboride)-based ceramics reinforced by 15vol.% SiC whiskers with high density were successfully prepared using MoSi 2 as sintering aids. The effects of sintering condition and MoSi 2 content on densification behavior, phase composition, and mechanical properties of SiC w /ZrB 2 composites were studied. Nearly, fully dense materials (relative density > 99%) were obtained by hot-pressing (HP) at 1700°C-1800°C in flow argon atmosphere. The grain size of ZrB 2 phase in the samples sintered by HP at 1700°C-1800°C were very fine, with mean size below 5 μm. Mechanical properties (such as flexural strength, fracture toughness, and Vickers hardness) of the sintered samples were measured. The sample with 15vol.% MoSi 2 addition sintered by HP at 1750°C displayed the best mechanical properties.