Tribological Properties Of Ti₃SiC₂ In Simulated Environment Condition Of High Temperature Gas Cooled Reactor

Layered ternary compounds titanium silicon carbide(Ti3SiC2) combines attractive properties of both ceramics and metals, and has been suggested for potential engineering applications. Near-fully dense Ti3SiC2 bulks were sintered from commercial Ti3SiC2 powders by hot press at 1400 °C for 90 min under Ar atmosphere in this thesis.This thesis researched the dry-sliding tribological properties of Ti3SiC2 under different test conditions, coupled with different counterfaces, including Ti3SiC2, Al2O3, Si3N4, SiC, and GCr15-bearing-steel. According to the result, Ti3SiC2 exhibited obviously different tribological properties with different sliding counterfaces at room temperature in air. The lowest friction coefficient(0.43) and wear rate(2.09×10-4 mm3/Nm) were obtained in the Ti3SiC2/SiC friction pair.Test temperature also has an effect on the dry-sliding tribological properties of Ti3SiC2. Increased friction coefficient and wear rate were observed if Ti3SiC2 slid against SiC ball at high temperature(200 °C) in air. If Ti3SiC2 slid against Ti3SiC2 and Si3N4, the friction coefficient and wear rate hadn't changed significantly. But more oxides were formed on the worn surface of Ti3SiC2 at high temperature in air.The effect of sintering temperature on the tribological properties of Ti3SiC2/Ti3SiC2 pair is obvious. When the sintering temperature is 1400°C, Ti3SiC2/Ti3SiC2 pair exhibits the lower friction coefficient and wear rate than other sample made in different sintering temperature. Variation trends of friction coefficient and wear rate of Ti3SiC2 are consistent with the density and flexural strength under different sintering temperatures. So we deduced that the tribological properties of Ti3SiC2 may be depended on its mechanical properties.Under argon atmosphere, Ti3SiC2 shows a completely different friction and wear performance. Interestingly, the five friction coefficients only vary in a range of ~0.2. It indicates that the friction coefficient is not depended on counterface materials, but the nature of Ti3SiC2 material. It found that fewer oxides were formed on the worn surface of Ti3SiC2 under flowing Ar gas at room temperature. Mechanical wear was the main mechanism.In the simulated environment condition of high temperature gas cooled reactor, the friction coefficients of all the friction pairs are increased, but the wear rates of Ti3SiC2/Ti3SiC2, Ti3SiC2/SiC and Ti3SiC2/Al2O3 pair are decreased. Lower wear rate is conducive to lengthen the service life of the material in the practical application. So it will be promising that the Ti3SiC2/SiC and Ti3SiC2/Al2O3 friction pairs applied to high temperature gas cooled reactor.