Ultrafine Al2O3/Cu composite powders,in whose copper matrix Al2O3 is uniformly dispersed,were obtained by spray drying-calcination-hydrogen reduction process with copper nitrate and aluminum nitrate as raw materials.Then Al2O3/Cu composites with different Al2O3 contents were prepared by hot-pressing sintering(HP)and molding-sintering-repressing-resintering(MP).The nature,microstructure,hardness and electrical conductivity of the samples prepared by the two methods were studied.The results show that the composites obtained by the two processes have high density.The hardness increases with the increase of alumina content and the conductivity decreases with the increase of alumina content.The Vickers hardness(143.9 HV)of the sample prepared by hot pressing sintering(HP)process is 93.9%higher than that of pure copper(74.2 HV)under the same process,and the conductivity is higher than 80.09%IACS.The Vickers hardness(136.8 HV)of the sample prepared by molding process(MP)is 223.4%higher than that of pure copper(42.3 HV)under the same process,and the conductivity remains above 82.25%IACS.
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