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In this paper, the carbon fiber, alpha-Al2O3 powder, BN powder as a raw material (alpha-Al2O3 with the BN a volume ratio of 3:1) was prepared using a hot press sintering process Cf/Al2O3-BN ceramic matrix composites. By means of XRD, SEM analysis and three-point bending, single edge notched beam method, test methods, Cf length, the influence of the sintering process of the mechanical properties of composites, thus Cf content on the mechanics of composite materials, thermal and anti- thermal shock resistance, the law of the impact of ablation performance. The results showed that the length of Cf respectively for 4mm, 8mm, 12mm when 20vol? / Al2O3-BN ceramic matrix composite flexural strength, fracture toughness and fracture reactive with the increase in the length of the carbon fiber increases. Further containing Cf Cf volume content unchanged length of 12mm (CLF) of the material introduced in 5 vol.% A 1mm short carbon fiber (CSF), the fibers are dispersed more uniformly (CLF CSF) / Al2O3-BN flexural strength and work of fracture there has been a certain improvement were 113.6MPa, 1596.3J/m2. 20vol.% (CLf CSf) / Al2O3-BN ceramic matrix composites (containing 1 vol.% sintering aid / substrate), respectively, in 1500 ° C, 1550 ° C, 1600 ° C, sintering at 1650 ° C, the density decreases with increasing temperature increases, flexural strength, fracture toughness and fracture work has gradually decreased; pressing sintering at 1500 ℃ were prepared containing 10 vol% sintering aids (CLF CSF) / Al2O3-BN composite material, its density, flexural strength, fracture toughness, fracture reactive improved, respectively, for 95.3%, 155.0 MPa 3.08 MPa · m1 / 2,2244.6 J / m2. Sintering in the 1500 ° C (CLF CSF) / Al2O3-BN composite materials, Cf volume content of respectively 15%, 20%, 25%, 30%, the flexural strength, fracture toughness with increased fiber content appears first add then decreased, the fiber content of 25 vol.% reaches a maximum of 170.5 MPa and 3.27 MPa · m1 / 2; work of fracture increases monotonically and reaches the maximum value, the fiber content of 30 vol%, 2883.6J / m2. The coefficient of thermal expansion and thermal conductivity of the composite material decreases with increasing fiber content. Thermal shock fracture parameters of composites with fiber content increases, the composite thermal shock residual strength decreased by carbon fiber oxidation and thermal elastic strain energy combined effects of. Composite materials (oxygen - acetylene flame) ablation process showed good ablation resistance. The composite ablation mechanism to thermal oxidation and mechanical erosion ablation based.
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