Preparation And Properties Of Zr₂SnC/Cu Composites

Due to the low strength, poor heat resistance and abrasion resistance and so on, theapplication of pure copper is severely constrained. While the improvement of strength andhardness of copper alloy is in the expense of conductivity and thermal conductivity.Copper matrix composites is famous for good conductivity and high strength, and becomea kind of functional materials with excellent properties. Layered ternary compounds（MAX） is a new type of conductive ceramics, with many excellent properties of metal andceramic, which is added to the copper as a particle-reinforeced phase. This will improvethe performance of copper gretely.The main purpose of this paper was to fabricate a Cu matrix composite reinforcedby Zr₂SnC particulates, which will make a good progress at strength, hardness, frictionperformance comparing with those of Cu matrix, without obvious decrease in theconductivity. The hot pressing sintering machine was used to prepare the materials. Thefirst step is to fabricate ceramic reinforced phase Zr₂SnC, which is crushed to particles inrequired size and mixed with the copper. Then, the mixed powder is sintered to cylinderblock. The metallographic microscope is used to analyse structure, and give thedistribution of Zr₂SnC particles. By using transmission electron microscopy （TEM） theinterface between Zr₂SnC and copper grain is observed. Actual density is measured andcompared to theoretical density by Archimedes method. Composite material conductivityis measured with four probe method. Microhardness meter is taken to measure hardness.Tensile test is executed in the tensile testing machine. Finally, the friction and wearexperiments will be done. The friction and wear performance of pure copper andcomposite material are compared, and the impact of load and velocity to fictioncoefficient and wear is analysed.The experimental results show that, the size of the Zr₂SnC is abou3⁵μm. Aftersurface modification, Zr₂SnC particle surface has been successfully plated a layer ofcopper grain. Microscopic structure analysis （OM） and transmission electron microscopy（TEM） analysis shows that the distribution of Zr₂SnC and copper particle is relatively uniform in the Zr₂SnC/Cu composite materials, and the bonding force of the two phase isquite strong. When Zr₂SnC content is6%, the theoretical density of the compositematerial is close to the actual density, so that the sample is dense. The electricalconductivity of sample is75%of annealing pure copper, and hardness is as1.65times asthe pure copper. Tensile strength is pure copper’s1.47times. Friction experiments showthat, the friction and wear of composite rate reduced a lot when Zr₂SnC is joined, and thewear mechanism is changed from adhesive wear to abrasive wear.