| The Cu/W composites combine the advantages of the tungsten and copper respectively, such as the high temperature strength, excellent electric corrosion resistance, high hardness, low thermal expansion coefficient and certain plasticity.Therefore, the Cu/W composites are widely used in the aerospace, electronics,machinery, electrical appliances and other industrial fields. The TiC phase has higher hardness, high melting point and excellent thermal stability. Some researches show that the dispersion TiC particles can effectively improve the low temperature brittleness and recrystallization temperature of tungsten. This work is focus on improving the comprehensive properties of Cu/W composite by adding different contents of TiC hard phases. The traditional preparation methods for fabrication of Cu/W composites are as follows, such as mixed powder sintering process, injection molding, mechanical alloying, sintered tungsten skeleton melt infiltration method, etc.But it is hard to control these methods to produce high density composite with low porosity.In this paper, the(Cu/50W)-TiC composites were prepared by powder metallurgy technology of the spark plasma sintering with different content of TiC. The parameters of the prepared materials are as follows, sintering temperature of 900°C, compaction pressure of 30 MPa, heating rate of 100℃/min and the holding time of 10 min. There are four(Cu/50W)-TiC composites were prepared vin this work. The properties, such as relative density, electrical conductivity, mocrohardness, and microstructures of the(Cu/50W)-TiC composites were tested and analyzed, as well as the effect of the content of TiC on them. The results show that the relative density of the(Cu/50W)-TiC composites are bigger than 95.0%, the microhardness and electrical conductivity are about 79~113HV0.2 and 43.2%?66.5%IACS, respectively.The wear resistance was investigated by a QG-700 atmosphere and high temperature friction and wear tester. The wear mechanism of the(Cu/50W)-TiC composites are mainly of abrasive wear.Using the Gleeble-1500 D simulator, the true stress-true strain curves and hot deformation behavior of the(Cu/50W)-TiC composites were determined and investigated respectively by means of the axial single pass isothermal compress method. The results indicate that the main mechanisms of the hot deformation of the(Cu/50W)-TiC composites are dynamic recrystallization in which the main effective factors were strain rate and deformation temperature. The thermal deformation constitutive equation of the(Cu/50W)-TiC composites were established based on the relationship among the flow stress, deformation temperature and strain rate.The electrical contact properties and their change rules, such as the fusion welding resistance force and contact electrical resistance, of the composites were tested by a model JF04 C electrical contact test system by means of the close-break test of electric contacts. The results show that under the test condition, the mass change of material transfer of the Cu/50 W and(Cu/50W)-3%TiC composites increases with the electrical current increasing. The material transfer direction of both composite is from the anode to the cathode. The main material transfer mechanism of the composites is attributed to the liquid bridge transfer type accompanied by some electrical arc transfer. The fusion welding resistance forces of the composites increase with the electrical current increasing and the operating times extending. The contact electrical resistance of the composites is stable during the test and it decreases with the test current increasing.The addition of 3%wt TiC has fewer effects on the fusion welding resistance force and the contact electrical resistance. |
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