Nanodiamond/Copper Composites Fabricated By Chemical Co-Deposition Metallurgy

Due to the properties of high hardness, high thermal conductivity, high wearing resistant, and the characters of nanoparticle, nanodiamond (ND) has attracted wide research attentions. ND reinforced metal matrix composites have a promising application in the fields which need the materials with high strength, high electric conductivity, and good high temperature performance. However, when ND was taken into consideration, a few problems, such as the aggregations of ND particles and the poor wettability between diamond and copper, could not be overcome by traditional preparation methods. In this paper, a novel method called"chemical co-deposition"was introduced to prepare ND/Cu composite powders. ND particles were functionalized by three modification methods for uniform dispersion, and ND/Cu composites were fabricated by powder metallurgy.ND/Cu composite powders were prepared by chemical co-deposition route, and ND/Cu composites were fabricated by powder metallurgy. The influence of different processing parameters (including: calcination temperature, reduction temperature, pressing, sintering temperature, sintering time and repressing) on the microstructure and performance of composite powders and ND/Cu composite bulks were investigated, and then processing parameters were optimized.The ND particles were modified by graphitization, acid treatment and electroless plating, respectively. The dispersibility of ND was great improved after modification. The ND particles, treated by graphitization and HF acid, could homogeneously disperse in composite powders and composite bulks. Fine grains and good interfacial combination of the composites were obtained. Thus, the surface treated ND/Cu composites show higher hardness and conductivity properties than untreated ones due to dispersion strengthen effect.The microstructure and interfacial characterization of ND/Cu composites were analyzed by TEM and HRTEM. The results demonstrated that ND particles homogeneously dispersed in copper matrix, and the interface between copper and ND was clean and tight. The grains of copper matrix were fine, and dislocations and twins in the matrix could be found. The influence of ND content on composites performances was studied. With the increase of ND content, the hardness, tensile strength and resistive softening properties of the composites could be improved, but the density and conductivity were decreased. 3wt.% ND/Cu composite has the best combined performances. The main strengthen mechanism of ND/Cu composites prepared by chemical co-deposition method are fine grain strengthening and dispersion strengthening.