Fabrication and properties of carbon fiber reinforced Al₂O₃-20% Ni metal-ceramic composites

The CF/Al₂O₃-20% Ni metal-ceramic composites with 0%, 5%, 10% and 15% volume fraction of carbon fiber (CF) were prepared by sol-gel method and hot-pressing sintering. The phase composition,surface and fracture morphology were analyzed by XRD, SEM and EDS. The effect of CF content on CF/Al₂O₃-20% Ni hardness, bending strength, fracture toughness was studied. The fracture morphology of composites was analyzed by SEM and its mechanism was discussed. The results show that CF/Al₂O₃-20% Ni composites with well dispersed CF and evenly distributed Ni particles was obtained, and can prevent the loss CF in the sintering process at high temperature by the formation of α-Al₂O₃ protective film layer on the CF surface. With the increase of volume fraction of CF, The hardness of the CF/Al₂O₃-20% Ni composites reduce, and its bending strength and fracture toughness first increase and then decrease. When the CF volume fraction is 10%, the bending strength and fracture toughness reach the maximum values, which increase by 79% and 134%, respectively, compared with the composites without CF. The addition of CF improves the strength and toughness of the CF/Al₂O₃-20% Ni composites. The toughening mechanism of CF/Al₂O₃-20% Ni is CF pull out, bridge and disbonding.