莫来石纤维增强氧化物多孔陶瓷及其性能研究

Preparation and Properties of Mullite Fiber Reinforced Oxide Porous Ceramics

以不同规格的粉煤灰漂珠、长石粉和铝矾土粉为主要原料,引入莫来石纤维为增强相,研究莫来石纤维含量对多孔陶瓷材料性能的影响规律及作用机理。结果表明:高温下长石粉中的低熔相能够降低材料的共晶熔点,将基质间的物理界面结合转变为化学结合。样品经1100℃烧成后,随着莫来石纤维含量的增加,多孔陶瓷的闭口气孔率增加,而常温耐压强度和体积密度呈现先增大后减小的趋势。当莫来石纤维含量为10 wt.%时,材料具有最佳综合性能,其体积密度为(0.74±0.01)g·cm^(−3)、真气孔率为(72.70±0.58)%,常温下耐压强度为(7.30±0.64)MPa。此外,试样在300℃、600℃及900℃下的平均热导率分别为0.202 W·m^(−1)·K^(−1)、0.214 W·m^(−1)·K^(−1)及0.244 W·m^(−1)·K^(−1)。

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.