| Ti2A1N is a typical compound of the Mn+1AXn（n=1,2,3）. Ti2 AlN bulk materials possess unusual properties of both metals and ceramics.Like metals, they are good thermal and electrical conductors, relatively soft and can be easily machined with traditional drill without lubrication or cooling water. Like ceramics, they are elastically stiff, exhibit excellent high temperature mechanical properties and high temperature oxidation behaviors. This study used Ti-Al-N series powder as raw materials and explored new ways to improve comprehensive performance of Ti2 AlN. In recent years, adding a fourth component X（X is Zr, Si, Ta, Nb, V, etc.） into the Ti-Al-N material could form some special nanophase, which significantly improved the overall performance of the material.These alloying elements could improve mechanical properties and thermal stability of Ti-Al-N to some extent. Recently,research work mainly concentrated on Ti2 AlN thin films and Ti2A1N/TiN composite material.However, the study of adding micro element into Ti2 AlN bulk material was rarely. In this study, Ti2 AlN bulk materials could be fabricated by non-pressurized sintering and hot-pressing（HP） at 1400℃, spark plasma sintering（SPS）at 1200℃, the mixtures with the raw materials ingredients of Ti、TiN、Al powder. This study mainly research on the effect of added C and Si on high temperature oxidation resistance of Ti2 AlN ternary compound ceramic. The results showed that:Spark plasma sintering 1200 ℃ was the optimum preparation of Ti2 AlN, the purity could be as high as 99.2%, The microstructure morphologies of samples were lamellar structure without any pore, the density of SPS samples was34.24g/cm, and the hardness was 4.1GPa. Especially for pure Ti2 Al N materials,the density of SPS samples increased by 52% compared with non-pressurized sintering samples.The size order of the density of SPS samples added C and Si was: added Si 0.2>added C0.1Si0.1>added C0.2>added Si0.1>added C0.1>pure Ti2 AlN, among them the density of samples added Si 0.2 increased by 4.3% compared with pure Ti2 AlN materials. The size order of the hardness of SPS samples added C and Si was: added Si0.2>added C0.1Si0.1>added C0.2>added Si0.1>added C0.1> pure Ti2 AlN, the hardness of samples added Si 0.2 was 5.8GPa which is the highest among them, which increased by 40%compared with pure Ti2 AlN.Added Si could significantly increase the high temperature oxidation resistance of Ti2 AlN ternary compound ceramic, while the influence of added C was less. The weight gain per unit area of added Si0.2 samples at 1000℃ was 14.89×10-3 kg.m-2, and of which the parabolic rate constants was 8.13×10-72-4-1kg.m.s, it was two order of magnitudelower than pure Ti2 AlN. Ti2 AlN ternary compound was excellent materials of high temperature oxidation resistance, because of Al2O3 formed in oxidation. Based on this,reactive formation of the samples added Si were both Al2O3 and SiO2, which significantly improved the high temperature oxidation resistance of Ti2 AlN samples.In conclusion, the spark plasma sintering is the optimum preparation of Ti2 AlN compared with non-pressurized sintering and hot pressing. SPS samples added C, Si significantly improved the high temperature oxidation resistance and other performance of Ti2 AlN samples. The research results will provide a new way not only for preparation of Ti2 AlN samples added micro element, but also for preparation of other high-performance ceramic materials. |
