Study On Preparation And Micro Structure And Properties Of In-situ ZrO₂/Cu Composites

This article selects the high hardness, good wear resistance and low thermal expansion coefficient of ZrO2particles as enhancement phase, first with high purity electrolytic copper and copper-zirconium intermediate alloy as raw material, Cu-0.6%Zr (mass fraction) alloy powders were prepared by vacuum melting and high pressure water atomization; Cu-ZrO2composite powders were obtained after separating particle size within the low temperature oxidation and N2+5%H2mixed gas reduction. And then, copper matrix composite materials reinforced with ZrO2particles were prepared by spark plasma sintering and powder canning hot extrusion. In order to optimize process parameters, various parameters on the microstructures and properties of ZrO2/Cu composite materials under different preparation process have been investigated. Also the high temperature resistance to softening of ZrO2/Cu composites and the effect of cold deformation on the microstructure and properties of its have been studied. The results show that:First, copper-zirconium alloy powder was prepared by water atomization method, zirconium content is0.6%. Cu-ZrO2composite powder was obtained after internal oxidation at230℃for1h and reduction at250℃for1h. The phase of Cu-ZrO2composite powder was analyzed by XRD diffraction pattern, the results show that the composite powder were mainly composed of α-Cu matrix composition; but the lattice constant of Cu in the composite powder (0.36167nm) is larger than that of pure copper (0.36150nm), indicating that Zr solid solution phase existed in the composite powder.Secondly, using Cu-ZrO1composite powder as raw materials, ZrO2/Cu composite materials were prepared by spark plasma sintering. The optimum parameters of ZrO2particles reinforced copper matrix composite materials which were made by spark plasma sintering are:sintering temperature of900℃, sintering time of2h, sintering pressure of30MPa; using Cu-ZrO2composite powder as raw materials, ZrO2/Cu composite materials with different extrusion ratio were obtained by power canning and hot extrusion when the extrusion temperature was900℃and extrusion speed was300mm/min, The extrusion ratio bigger, the comprehensive performance of the ZrO2/Cu composite materials is better. Compared to the spark plasma sintering (SPS), the comprehensive properties of ZrO2/Cu composite materials was better, which was prepared by powder canning and hot extrusion.The last, effect of cold deformation on mechanical properties of ZrO2/Cu composite were studied. When the drawing deformation of Φ32mm ZrO2/Cu composite material was43.75%, the hardness of its increased from83.94HV to116.75HV, an increase of39%, and its conductivity reached to80.86%IACS. We studied the high temperature softening properties of ΦD32mm ZrO2/Cu composite materials when its drawing deformation was43.75%and, results show that its softening temperature exceeded800℃, far greater than the softening temperature (150℃) of pure copper. By SEM and XRD characterization analysis, results show that the enhancement particle is ZrO2, the particle size is less than1μm, these particles are dispersion distributed in the matrix.In this paper, the ZrO2/Cu composite materials own better comprehensive properties by internal oxidation combined with powder hot extrusion. The experiment results can provide theoretical basis and data support for the research and development of new copper matrix composites.