纤维增强ZrO_(2)泡沫陶瓷的制备及导热性能

Preparation and thermal conductivity of high-strength zirconia foam ceramics

ZrO_(2)气凝胶具有比表面积大、吸附能力强、隔热等优异性质,在催化剂载体、气体过滤材料、高效隔热材料、高温构件等领域具有广阔的应用前景。然而,氧化锆气凝胶在高温环境下因晶型转变导致孔结构破坏、骨架结构坍塌而表现出较差的力学性能,使其在实际应用中受限。采用纤维增强方法,在高热稳定氧化锆气凝胶基础上,通过H_(2)O_(2)发泡法制备了高强度ZrO_(2)泡沫陶瓷,并对其进行了制备工艺以及高温热温度性、表观密度、气孔率、抗压强度和导热性能进行测试分析。测试结果表明,气凝胶与纤维增强结合的泡沫陶瓷经5 h、1400℃高温处理后仍然保持四方晶相结构,表现出优良的高温热稳定性。当纤维含量为35%时,氧化锆泡沫陶瓷抗压强度最佳,为15.3 MPa。当纤维含量为30%、H_(2)O_(2)与ZrO_(2)气凝胶质量比为4∶8时,泡沫陶瓷的表观密度最低,仅为1.104 g·cm^(-3),气孔率为81.6%,且分别在室温、1000℃条件下,泡沫陶瓷的导热系数分别为0.451和0.712W·K-1·m^(-1)。

Zirconia aerogel which characterized with excellent properties such as high specific surface area,strong adsorption performance,low thermal conductivity,etc.has broad application prospects in the fields of catalyst carrier,gas filter materials,efficient thermal insulation materials and so on.However,it exhibits poor mechanical properties due to the pore structure destruction and skeleton structure collapse caused by crystal transformation at high temperature,which limits their practical application.In this work,high strength zirconia foam ceramics were prepared by direct foaming method with high thermal stability zirconia aerogel and reinforced zirconia fiber.The results show that the prepared foam ceramics remained tetragonal after 5 hours treatment at 1400℃,indicated good thermal stability at high temperature of foam ceramics.With 35% fiber content,the compressive strength of zirconia foam ceramics is 15.3 MPa.With 30% fiber content and m H_(2)O_(2):m A-ZrO_(2)=4∶8,the density of foam ceramics is the lowest,only 1.104 g/cm^(3),and the total porosity is 81.6%.The thermal conductivity of foam ceramics is 0.451 W/(K·m)at room temperature and 0.712 W/(K·m)for 1000℃.