Preparation And Properties Of Copper Matrix Composites Reinforced By Amorphous SiO₂Coated SiC Particle

Cu/SiCp composites combine both the high electric-conductivity of copper and superior specific modulus of SiC, having broad application prospects in the automotive industry, electronics and advanced weapons systems. The content of silicon carbide reinforcement and the two-phase interface of silicon carbide and copper have an important impact on the property of composite materials. Adding reinforcement silicon carbide particles and the reasonable regulation of the two-phase interface can get two-phase homogeneous and excellent performance composite materials.This article firstly adopt sol-gel to realize surface preparation of micron silicon carbide via coating it with amorphousness SiO2and then coating the surface of precursor SiC with Cu by replacement reaction method to prepare Cu/SiC(SiO2) composite powders. Differential Thermal Analysis (DTA), X-ray diffraction (XRD), Zeta potential instrument, scanning electron microscopy (SEM)and other detection methods were used to characterize the composition and structure of composite powders. Vacuum hot pressing method was used to fabricate silicon carbide reinforced copper matrix composites. Some properties such as composite microstructure, composition and density, were characterized to analysis the preparation process parameters on the structure and properties of composites. Finally, the electric properties of silicon carbide particle reinforced copper matrix composites were measured, researching the impact of SiO2interface control on the high-temperature resistivity of composites and analyzing the interfacial properties of materials according to the effect of space charge.Experimental results show that:the use of sol-gel method could coat surface of SiC particles with a layer of amorphous SiO2. The reaction system ratio, temperature and pH of the reaction system have impact on the effect of coating. Chemical replacement reaction was carried out to prepare composite powders of Cu coated SiC-SiO2. The existence of SiO2could promote the combination of the two-phase wetting behavior. It was showed that eutectic mixture of Cu2O-SiO2appeared at about1058℃though thermal analysis of composite powders. When it was up to1148℃the SiO2began to transform from amorphous to crystal and when the temperature is higher than1170℃, serious interfacial reaction between Cu and SiC generate a variety of CuxSi compounds. Cu/SiC(SiO2) composites could be fabricated by vacuum hot pressing sintering method. Performance analysis shows that:the composites show relatively excellent property under the conditions of enhanced particles25vol.%SiC,20%of the total volume of SiO2addition, the synthesis temperature of50℃and vacuum hot pressing temperature of800℃. During the hot pressing sintering process, Three mass transfer mechanism (the flow and mass transfer, the diffusion and mass transfer and the dissolution precipitation mechanism) were explained the densification of the composite material. The analysis of the electrical properties of Cu/SiC revealed that the existence of SiO2can significantly change the Cu/SiC interface structure and the composite components of interface, and significantly change the space charge of the composite interface polarization behavior.