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Nearly pure Ti 3 AlC 2 powders have been synthesized by calcining a mixture of titanium, aluminum, and graphite powders using tin powders as additives. Four recipes with different mole ratios of Ti:Al:C:Sn were examined at calcining temperatures from 13001 to 15001C. The addition of Sn effectively inhibited the generation of thermal explosion when the volume of the starting materials is larger, and considerably reduced the lowerlimit calcining temperature. The nearly pure Ti 3 AlC 2 powders can be obtained reliably on a large scale by calcining the starting materials with a mole ratio of 3Ti:1Al:1.8C:0.2Sn at temperatures from 13501 to 15001C. J ournal

Tribological behaviors and the relevant mechanism of a highly pure polycrystalline bulk Ti 3 AlC 2 sliding dryly against a low carbon steel disk were investigated. The tribological tests were carried out using a block-on-disk type high-speed friction tester, at the sliding speeds of 20-60 m/s under a normal pressure of 0.8 MPa. The results showed that the friction coefficient is as low as 0.1$0.14 and the wear rate of Ti 3 AlC 2 is only (2.3-2.5) Â 10 )6 mm 3 /Nm in the sliding speed range of 20-60 m/s. Such unusual friction and wear properties were confirmed to be dependant dominantly upon the presence of a frictional oxide film consisting of amorphous Ti, Al, and Fe oxides on the friction surfaces. The oxide film is in a fused state during the sliding friction at a fused temperature of 238-324°C, so it takes a significant self-lubricating effect.

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