Al-La thermal diffusing was conducted on Ti3SiC2-base ceramic by the pack-cementation method. The microstructure, phase and oxidation resistance of the diffusion layer were characterized. The complete aluminide coatings have not been obtained. Al and La penetrated into the Ti3SiC2 substrate quickly, distributing into the whole interior of the specimen after cementation at 1100degrees C for 4 hr. Al existed as a solid solution and dispersed particles of AlLa3. Oxidation of cemented Ti3SiC2 at 1100degrees C in air for 20 hr formed a single continuous Al2O3 layer with a small amount of TiO2 grains on the outer layer. Compared with Ti3SiC2, the parabolic rate constant of the cemented Ti3SiC2 was decreased by two orders of magnitude, which means that the cementation treatment remarkably improves the oxidation resistance of Ti3SiC2. Al distributed in Ti3SiC2 acted as "a reservoir'' to supply enough Al for the formation of a continuous Al2O3 scale during the oxidation process.
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