Fly ash cenospheres,feldspar powder and alumina powder with various specifications were utilized as the raw materials and mullite fibers were introduced as a reinforcing phase to fabricate porous ceramics.The effect of mullite fiber on properties of the porous ceramics and the mechanism were studied.It is indicated that the incorporation of low-melting phases from feldspar powder at high temperatures was employed to reduce the eutectic point of materials,transforming the physical interface between the matrix phases into a chemical bond.An increase in mullite fiber content led to rise in closed porosity of the porous ceramics after sintering at 1100 ℃.Simultaneously,room-temperature compressive strength and bulk density initially increased and then decreased with rising content of mullite fiber.Optimal comprehensive performance was achieved when the mullite fiber content was 10 wt.％,resulting in a volume density of(0.74±0.01)g·cm-3,a true porosity of(72.70±0.58)％,and a room-temperature compressive strength of(7.30±0.64)MPa.In addition,average thermal conductivities of the specimens at 300 ℃,600 ℃ and 900 ℃ were 0.202 W·m-1·K-1,0.214 W·m-1·K-1 and 0.244 W·m-1·K-1,respectively.
维普
万方数据