酚醛气凝胶/炭纤维复合材料的结构与烧蚀性能

The microstructure and ablation behavior of carbon fiber/phenolic aerogel composites

分别以密度为0.15 g/cm^3的铺层炭纤维毡和炭纤维穿刺编织体作增强体,采用酚醛树脂浸渍炭纤维,经溶胶-凝胶过程,制备出不同密度和结构的酚醛气凝胶/炭纤维复合材料(PAC)。研究表明,所制复合材料具有轻质(0.27～0.40 g/cm^3)和低热导率(0.056～0.068 W·(m·K)^(-1))特点;炭纤维穿刺编织体复合材料(P-PAC)的弯曲强度是铺层炭纤维毡复合材料(L-PAC)的2倍,当P-PAC密度为0.40 g/cm^3时,其弯曲强度可达35.9 MPa;P-PAC具有更优的耐烧蚀性能,在2 000℃、60 s的烧蚀条件下,其质量烧蚀率为0.0043 g/s、线烧蚀率为0.0147 mm/s。酚醛粒子因纳米尺寸效应能够完全分解、蒸发、升华,充分带走表面热,而气凝胶多孔结构也有效的阻止表面热量向内部传递,因而酚醛气凝胶/炭纤维复合材料具有优异的微烧蚀/隔热一体化功能。

Carbon fiber/phenolic aerogel composites（ C/PA） were prepared through sol-gel polymerization of a phenolic resin followed by ambient pressure drying using carbon fiber mats as the reinforcements. The composites have low densities（ 0. 27-0. 40 g/cm3） and low room-temperature thermal conductivities（ 0. 056-0. 068 W·（ m·K）（-1））. The bend strength of the composite prepared from the pierced carbon fiber mat（ P-C/PA） is twice that of the laminated carbon fiber mat（ L-C/PA）. The highest bend strength obtained was 35. 9 MPa for the P-C/PA with a density of 0. 40 g/cm3. Under ablation at 2000 ℃ for 60 s,the mass and linear ablation rates of the P-C/PA were 0. 0043 g/s and 0. 0147 mm/s,respectively. The phenolic nanoparticles in the aerogel were easily decomposed,evaporated and sublimed to remove superficial heat while the porous network of the aerogels effectively prevented heat transfer from the surface to the interior of the composite. C/PA composites are excellent candidates for bifunctional ablation/insulation applications.