A Study On The Property Of Cu-Ti₃SiC₂Composite Materials Prepared By Different Techeniques

Titanium silicon carbide （Ti₃SiC₂） is a new class of ceramic material. Its theoreticaldensity is4.53g/cm3and melting point is3000℃. It has excellent electric and thermalconductivity which is similar to metal. Ti₃SiC₂has many unique properties, such ashigh temperature plasticity, excellent thermal shock, high melting point, excellent corrosionresistance, high yield strength and oxidation resistance, etc. These unique properties enable itto a wide range of future applications. In this work, we fabricated Ti₃SiC₂by pressurelessreactive sintering and we also studied the effect of caping and sintering atmosphere.Cu Ti₃SiC₂composit were prepared by adding Ti₃SiC₂powder of5wt%,15wt%,25wt%,35wt%into the copper powder using different forming and sintering technologies.Ti₃SiC₂bulks were obtained by using Ti, Si, C power as raw materials. The experimentswere done either under vacuum or argon atmosphere with different starting molar ratio.Results show that caping do have effect on the purity of Ti₃SiC₂. The better the caping is, theless the amount of the impurities is. The purities of Ti₃SiC₂were also affected when sinteredunder different sintering atmosphere.It turns out that the purities of Ti₃SiC₂will get a betterresult when sintered under vacuum atmosphere. In terms of the volatility of silicon, we canget pure Ti₃SiC₂when sintered in a caping device under vacuum by using a ratio of3Ti:1.2Si:1.8C.By pressureless sintering, experimental results show that the density of the Cu Ti₃SiC₂composites decreases, resistivity, and the hardness is increased first and then decreased withthe increase of the Ti₃SiC₂content. The relative density of the composite prepared by thismethod is low. The relative density is93.4%when the content of Ti₃SiC₂is5wt%. It is71.6%when the content of Ti₃SiC₂is35%, which contains high porosity. Its comprehensiveperformance declined when the added Ti₃SiC₂content is high, so the process is not suitablefor the preparation of composite with high Ti₃SiC₂content. By the method of repressing andresintering process, results show that the relative density of the composite is improved withthe increase of the repressing pressure. When the pressure is400MPa, its relative density mayreach95%. So the repressing and resintering process is beneficial to increase density,hardness, conductivity, friction coefficient. By taking friction and wear experiment underelectricity and no electricity, it turns out that the friction coefficient under electric current issmaller than that without electric current, while, the wear volume are just the opposit.By using high velocity compaction to prepare a series of specimen which containingdifferent Ti₃SiC₂content, and exploring the room temperature and120℃high velocitycompaction on the properties of the specimen. Experimental results show that, at room temperature, the green density and sintered density decreased with the increase of the Ti₃SiC₂content. The green density is higher than the sintered one. The hardness and resistivityincrease with the Ti₃SiC₂content increased, when the Ti₃SiC₂content is35wt%, thehardness is175HB, which is much higher than pure copper. The green density and sintereddensity under room temperature compaction decreased with the increase of Ti₃SiC₂. And thegreen density is lower than that of the sintered sample. When the Ti₃SiC₂content is the same,warm compaction is better than room temperature compaction. So preparing sample underhigher temperature is beneficial to improve the comprehensive performance of compositematerials. The bend strenth by warm compaction is higher than those prepared by the roomtemperature compaction, when Ti₃SiC₂is25wt%, its bend strenth is603.1MPa.Compared with the pressureless sintering and resintering methods, the performance ofhigh velocity compaction samples are significantly better, but its relative density need to beimproved, therefore, taking the spark plasma sintering to prepare the Cu Ti₃SiC₂composite.Experimental results show that spark plasma sintering can greatly improve the density of thematerial. When the Ti₃SiC₂content is less than25wt%, its relative density is more than99%,while the Ti₃SiC₂content is35wt%, its relative density is96.6%. Therefore, the density,hardness, resistivity, and friction coefficient of the sample prepared by spark plasma sinteringhas a great improvement when compared with other processing methods.