The Research Of Fe₃Si Based Composites Reinforced By Surface-Modification Carbon Fiber

Metal silicide compound (Fe3Si) has aroused wide public concern because of its various excellent properties which include high temperature resistance, oxidation resistance and corrosion resistance and above all the soft magnetic properties. Fe3Si which was used as a kind of potential high temperature structural materials not only its simple preparation method but also the low cost. However, just like other intermetallic compound, the lack of strength deficiencies in high temperature becomes its shortcoming. Hence, how to improve the toughness of Fe3Si at low temperature and enhance the strength of Fe3Si at high temperature is the key for Fe3Si alloys to be practical.This study adopts the method of adding carbon fiber to improve the toughness of Fe3Si at room temperature, get the following results:1. After the acid-pickled method, short carbon fibers were uniformly dispersed in the solution whichocomposition contains copper sulfate, sodium citrate, sodium tartrate and potassium nitrate. Then, in electromagnetic stirring condition, by used long untreated carbon fibers as cathode, electrolytic Cu plate as anode and2V voltage,30minutes deposition, we developed the stubby carbon fibers on which surface was covered with copper uniformly.2. After pickling, the short carbon fibers were dispersed into AlOOH sol, drying after the coating, and after high temperature treatment, uniformly Al2O3-coated carbon fiber was produced. After repeated wrapped for three times, the thickness of Al2O3-coated layer had been effectively increased and a dense coating layer has been obtained.3. The reinforced phases of carbon fibers are uniformly dispersed in Fe3Si matrix and closely integrated with each other, so the three-point bending strength improved, the coated carbon fibers played enhancement from240MPa to339MPa rather than uncoated carbon fibers from240MPa to309MPa.4. The Al2O3-coated carbon fibers also improved the properties of the Fe3Si-Cu matrix, but the toughening effect was not obvious due to the poor interfacial bonding, the three point bending strength only improved from338MPa to357MPa. But after Cu-coating, the bonding strength became favorable, therefore, a better toughening effect was achieved expectedly, three point bending strength achieved454MPa.