Fabrication And Properties Of W-SiC_p/Cu Composites By Hot Pressing Sintering

Cu has good electrical conductivity and thermal conductivity. SiC has lowthermal expansion coefficient, high elasticity modulus and low density. W has highmelting point, high density, hardness, strength, good wear resistance and thermalstability, low expansion of thermal coefficient and high strength. The combination ofthe advantages of Cu, SiC and W has made the novel W-SiCp/Cu composite become apotential candidate material for a variety of high-tech application. Many studies havebeen focused on the SiC-Cu, W-Cu binary composites, however there hasn’t beenmuch report about the W-SiCp/Cu ternary composite material. This paper is aboutW-SiCp/40vol.%Cu composite with different W content(0vol.%,20vol.%,30vol.%,40vol.%and60vol.%) which fabricated by vacuum hot-pressing sintering. Studyabout the effect of sintering temperature, pressure and holding time on densification,phase(XRD) and microstructure(SEM,EPMA) of W-Cu-SiC composite.In order to determine the best sintering process for W-SiCp/Cu ternary composite,the research results show that the sintering temperature, pressure and holding timehad no significant effect on the material phase, and have some influence on thematerial density. According to the EPMA result, overheating would result in thedissolving of SiC and the diffusion of Si to Cu phase, which is negative forfabrication. According to the SEM images, sintering temperature, pressure andholding time have positive effect on porosity reducing and promote sintering. Whenthe sintering temperature is950°C, pressure is100Mpa and holding time is2hours,composite materials have compact structure with no obvious holes. W and SiCparticles distribute uniformly in the substrate.The driving force of densifying mechanism of W-SiCp/Cu composite material issintering temperature, pressure and holding time, which would accelerate the plasticdeformation and flowing of Cu, and fill the pores and promote the sintering. Thismechanism determine the fracture mode of material is intergranular fracture betweenSiC and Cu, W and Cu, the ductile fracture of Cu and the transgranular fracture of Wparticle. According to W-SiCp/Cu composite material fabricated by the best sinteringprocess with different W content, we study about effect of the content of W ondensity， microstructure, phase, etc. The results show that the density of theW-SiCp/Cu composite material can be up to99.3%with the best sintering process andit improved with the increasing of W content. The poor wettability between W and Culead to better sinterability compared with SiC and Cu. W content have no influence tothe phase of composite material. With the increasing of W content, the microstructureof composite material get better compact, without the obvious hole. Due to the poorinterfacial binding force between SiC and Cu, there exist the interface cracks betweenSiC and Cu and failure phenomenon of SiC particles of the low W content sample.The relationship of W content and the performance of W-SiCp/Cu compositematerial are studied according to measurement and characterization result. With theincreasing of the W content, the flexural strength increases from130MPa to476MPaand Vickers hardness decreases from282HV to227HV. The bulk sound velocity ofmaterial is3.575-4.259km/s, which fits the prospect result from the mixture modeland shares the same change rule with the mixture model. So the bulk sound velocityof material can get from the mixture model. Between50-500°C, coefficient ofthermal expansion of material with different W content is8.3-12.3×10-6K-1. Sampleswith high W content share the same regular between temperature and coefficient ofthermal expansion. Thermal conductivity of material increases from99W/mK to212W/mK. These mechanical and thermal properties research are referential tofurther study and application of W-SiCp/Cu composites material.