Process for preparing composite materials capable of forming oxidation-resisting structure on the surface of fiber by in-situ reaction
A composite material and fiber surface technology, applied in the field of ceramic matrix composite materials, can solve the problems of complex process and high equipment requirements, and achieve the effect of simple process, high density and easy adjustment
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Embodiment 1
[0027] C fiber in nanometer or submicron SiC (with Al 2 o 3 and Y 2 o 3 It is a sintering aid, the external addition is 4wt%) in the slurry (the slurry uses polycarbosilane as a dispersant and a binder), then wound on a reel, and after drying, the temperature is 800 ° C under vacuum conditions Debond under the pressure, cut into the required shape with a scalpel, and finally prepare the required composite material by hot pressing and sintering in a graphite mold. The sintering conditions are: temperature 1850°C, pressure 20MPa, holding time 1 hour. The microstructure of C / SiC composites is as follows: figure 1As shown, an obvious SiC in situ reaction layer is formed on the surface of the fiber. However, there is no reaction layer on the surface of the composite material prepared at lower temperature, such as figure 2 shown. It shows that the preparation temperature has a great influence on the in situ reaction.
Embodiment 2
[0029] C fiber in nano-SiC (with Al 2 o 3 and Y 2 o 3 It is a sintering aid, the external addition amount is 5wt%), impregnated in the slurry (the slurry uses phenolic resin as the dispersant and binder), then wound on the reel, after drying, at a temperature of 800 ° C, under vacuum conditions Carry out debonding, cut into the desired shape with a scalpel, and finally prepare the required composite material by hot pressing and sintering in a graphite mold. / SiC composite cross-section microstructure such as image 3 As shown, the fiber surface becomes rough due to the formation of SiC in situ reaction layer on the fiber surface. On the one hand, the in-situ reaction strengthens the combination of fiber / matrix, on the other hand, it increases the resistance to fiber pull-out, and enhances the load transfer ability from the matrix to the fiber. The strength of the composite material reaches 500 MPa. However, the surface of the composite fiber prepared at a lower temperatur...
Embodiment 3
[0031] C fiber in nano-SiC (with Al 2 o 3 and Y 2 o 3 It is a sintering aid, the addition amount is 5wt%) in slurry (slurry uses polycarbosilane as dispersant and binding agent) and impregnated, then on a thin rod to form a small cylinder. After drying, debonding is carried out at a temperature of 800°C and an argon atmosphere, and finally the required columnar C / SiC composite material is prepared by hot pressing and sintering in a graphite mold. The sintering conditions are: temperature 1900°C, pressure 30MPa, holding time 0.5 hours. The columnar C / SiC composite material is ablated under the condition of >3000°C and air, and the ablation rate is <0.38mm / min, showing good oxidation resistance and ablation resistance.
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