The Research Of Fe₃Si/α-Al₂O₃ Composites Strengthened And Toughened By Surface-modified Carbon Fiber

Intermetallics Compounds Fe₃ Si has high melting point, and have excellent high temperature resistance, corrosion resistance and oxidation resistance, and the price is low, its constituent elements is a kind of potential high temperature structural materials, has a good prospect in engineering application.But Intermetallics Compounds Fe₃ Si brittleness at room temperature, high temperature strength greatly limits its application in structural materials,therefore to strong Fe₃ Si Intermetallics compounds is the key to Fe₃ Si material for practical application.This article adopts the method of mechanical alloying and hot pressed sintering preparation of Cf-Fe₃Si/α-Al₂O₃ composite materials, mainly for carbon fiber and carbon fiber surface coated Al₂O₃ content affect the performance of composite material mechanics,screening the best mechanical properties of composite material system and preparation;To further investigate the carbon fiber surface treatment on the influence of the microstructure of composite system.First use the iron oxide, aluminum powder and silicon powder prepare Fe₃Si/α-Al₂O₃ composite powder by mechanical alloying method of ball grinding. This is to introduce alumina into Fe₃ Si enhance phase;And then the method of using sol gel coating on carbon fiber surface deposition of alumina, the carbon fiber surface after the deposition of alumina and Fe₃Si/α-Al₂O₃ composite powders by mechanical mixing, through hot pressing sintering device for composite powders calcined, preparation of block to Cf-Fe₃Si/α-Al₂O₃ composites.During the trial the Fe₃Si/α-Al₂O₃ powders, the increase of phase carbon fiber have been characterized and principle analysis, and the preparation of different carbon fiber volume fraction of Cf-Fe₃Si/α-Al₂O₃ content phase analysis on composite material, three point bending strength analysis, analysis of fracture, and the microstructure and properties of composites were characterized and analyzed.The experiment results are as follows:1.Cf-Fe₃Si/α-Al₂O₃ composite materials on the surface of carbon fiber reinforced phase in the after alumina sol gel method deposition coating, increase the wettability of carbon fiber and composite matrix, and can effectively reduce the carbon fiber and matrix interface reaction, greatly increase the carbon fibers and the bonding strength of the composite, thus toughening effect of composite material;2.After the Cf-Fe₃Si/α-Al₂O₃ composites microstructure and properties were analyzed,and found that by hot-pressing sintering preparation of Cf-Fe₃Si/α-Al₂O₃ composites,organization is compact, carbon fiber no preferred orientation, uniform distribution ofcomposite block, by EDS analysis was carried out on the composite materials, composite materials uniform distribution of various elements, and it have no obvious phenomenon of reunion.3.On Cf-Fe₃Si/α-Al₂O₃ composite material mechanical performance test, found that with the increase of carbon fiber volume fraction, the compound material of three point bending strength increased, the carbon fiber volume fraction of 8%, the three point bending strength of the composite reached its maximum 199 MPa, along with the increase of carbon fiber volume fraction, the three-point bend a downward trend of the composite, through analysis of three-point bend specimens of port, the strength of carbon fibre mechanism to pull out and pull off mechanism;...