The 2.5 dimensional silica fiber reinforced nitride matrix composites (2.5D SiO2f/Si3N4-BN) were prepared through the preceramic polymer impregnation pyro- lysis (PIP) method. The ablation and radar-wave transparent p...The 2.5 dimensional silica fiber reinforced nitride matrix composites (2.5D SiO2f/Si3N4-BN) were prepared through the preceramic polymer impregnation pyro- lysis (PIP) method. The ablation and radar-wave transparent performances of the composite at high temperature were evaluated under arc jet. The composition and ablation surface microstructures were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the 2.5D SiO2f/Si3N4-BN composites have a linear ablation rate of 0.33 mm/s and high radar-wave trans- parent ratio of 98.6%. The fused layer and the matrix are protected by each other, and no fused layer accumulates on the ablation surface. The nitride composite is a high-temperature ablation resistivity and microwave transparent material.展开更多
The boron nitride fibers were heated at the range of 600-1400oC in flowing nitrogen and air, respectively, and the effects of heat treatment on the structure, composition and morphology of BN fibers were studied. The ...The boron nitride fibers were heated at the range of 600-1400oC in flowing nitrogen and air, respectively, and the effects of heat treatment on the structure, composition and morphology of BN fibers were studied. The results showed that BN fibers exhibited smooth surfaces, and that t-BN was the main phase with a little B2O3 included. After heat treatment at 1400oC in nitrogen atmosphere, the fibers displayed rough surfaces with little change in mass. Better crystallinity was obtained with the increasing temperature. During heat treatment in air, the fibers were oxidized severely as the temperature went up, especially at 1400oC. The volatilization of B2O3, HBO2 and H3BO3 led to the pores on the surfaces of the fibers, while the boron oxide glaze and nitrogen gas produced during the oxidation process protected the fibers from further oxidation.展开更多
基金the State Key Laboratory of Advanced Ceramic Fibers & Composites Foundation (Grant No. 2004js51488.0101.kg01.3) the Innovation Foundation of National University of Defense Technology for Graduate Students (Grant No. 0603)
文摘The 2.5 dimensional silica fiber reinforced nitride matrix composites (2.5D SiO2f/Si3N4-BN) were prepared through the preceramic polymer impregnation pyro- lysis (PIP) method. The ablation and radar-wave transparent performances of the composite at high temperature were evaluated under arc jet. The composition and ablation surface microstructures were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the 2.5D SiO2f/Si3N4-BN composites have a linear ablation rate of 0.33 mm/s and high radar-wave trans- parent ratio of 98.6%. The fused layer and the matrix are protected by each other, and no fused layer accumulates on the ablation surface. The nitride composite is a high-temperature ablation resistivity and microwave transparent material.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50902150, 90916019)the Graduate Innovation Foundation of the National University of Defense Technology (Grant No. S100103)
文摘The boron nitride fibers were heated at the range of 600-1400oC in flowing nitrogen and air, respectively, and the effects of heat treatment on the structure, composition and morphology of BN fibers were studied. The results showed that BN fibers exhibited smooth surfaces, and that t-BN was the main phase with a little B2O3 included. After heat treatment at 1400oC in nitrogen atmosphere, the fibers displayed rough surfaces with little change in mass. Better crystallinity was obtained with the increasing temperature. During heat treatment in air, the fibers were oxidized severely as the temperature went up, especially at 1400oC. The volatilization of B2O3, HBO2 and H3BO3 led to the pores on the surfaces of the fibers, while the boron oxide glaze and nitrogen gas produced during the oxidation process protected the fibers from further oxidation.
