Fabrication And Properties Of Cu-Ti₃AlC₂ Cermet

According to requirements of the basic scientific study of the state "863" program for "applications of Ti₃SiC₂ series materials in the high-speed train pantograph strip ", a batch process of the high purity Ti₃AlC₂ powders was investigated. Influences of the sintering temperature, the holding time and the ratio of raw materials on purity of reaction products were studied in details, and the effect of Sn used as additive in synthesizing high purity Ti₃AlC₂ powders was investigated too. Then, a Cu-Ti₃AlC₂ cermet with excellent properties was fabricated by sintering the Ti₃AlC₂ and Cu mixed powders with different methods, and some of its properties were characterized.The results showed that, the optimum process of synthesizing high purity Ti₃AlC₂ powders was to sinter Ti, Al, C with a molar ratio of 3:1.1:1.8, at 1450℃ for 5 minutes in the Ar atmosphere. However, a thermal explosion behavior which reduced the purity of reaction products always generated when a larger volume of Ti₃AlC₂ powders was synthesized.Sn , as an additive, effectively inhibited the thermal explosion behavior, and thus solved the key technology in synthesizing high purity Ti₃AlC₂ in large scale. The results showed that, proper quantities of Sn additive, not only inhibited the thermal explosion, but also significantly reduced the synthesis temperature and broadened the range of the synthesis temperatures. Reaction products with more than 98vol.% of Ti₃AlC₂ were obtained in the temperature range of 1350℃-1500℃.Reaction between Cu and Ti₃AlC₂ was studied via DSC analysis and electric microscopic examinations. The results showed that, the reaction between Cu and Ti₃AlC₂ was a process of mutual diffusion of Al and Cu, which made Ti₃AlC₂ dissociate into Ti₃C₂-Ti₃C₂-Ti₃C₂ layered structure, and made Al atoms combine with Cu atoms. Consequently, a very special " Ti₃C₂- Cu-Al-Ti₃C₂" alternate layered structure was formed.The pressureless sintering process and the pressureless infiltration sintering process were tried to fabricate a high-performance Cu-Ti₃AlC₂ cermet, the volume ratio of Ti₃AlC₂ and Cu has a fundamental effect on properties of the prepared cermet. The results showed that the flexural strength, the hardness and the electrical resistivity increased with the increasing content of Ti₃AlC₂. When the volume ratio was Ti₃AlC₂:Cu =9: 1,the flexural strength, the Vickers hardness and the electrical resistivity...