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W2B5-SiC-BN-C composites were prepared by reaction hot-pressing to develop a new material for dynamic sealing. The influences of sintering temperature and volume fraction of in-situ formed W2B5, SiC, BN in the composites on microstructure, room temperature mechanical properties, room temperature friction and wear properties, and high temperature oxidation behavior have been studied in details. Mechanisms of strengthening, friction and wear, and oxidation behavior of the composites have also been investigated.The relative density of the composites increases with increasing content of W2B5, SiC and BN, and there is a small increment at the content of W2B5 higher than 10 vol%. The relative density of W5BS30 composites is 91.2%, it of the W10BS30 composites achieves 96.9%, and 97.3% of the W15BS30 composites.With increasing the W2B5, SiC and BN content, there is a obvious increase in the quantity of plate-like morphology structure. And we can see that the W2B5 is equiaxed, granular SiC particles distributed in the carbon-based body.The flexural strength, fracture toughness and Vickers hardness of the W2B5-SiC-BN-C composite increase with the increasing content of W2B5, SiC and BN. The flexural strength, fracture toughness and Vickers hardness of the W15BS30 composite fabricated at 2000℃all have maximum values, they are 174MPa, 2.4MPa?m1/2 and 1.41GPa respectively.Tribological properties of materials are closely related to the contents of the composites and test loads. The friction coefficients of the composites increase with the increasing content of W2B5, SiC and BN, and wear of composites are smaller than that of graphite. The composites have low friction coefficients because of the formation of the mechanical mixed graphite-rich layer covering on the worn surface. The delamination, fracture and breaking off of the mechanical mixed layer are the main wear mechanism.The weight losses of the composites when oxidized at 600℃, 800℃and 1000℃are obviously reduced compared with carbon materials, and the weight losses of the composites increase with increasing temperature. There was no oxide layer found on the surface of the composites when oxidized at 600℃. The B-Si-O layers were formed when oxidized at 800℃and 1000℃, which is believed to be the main mechanisms to the high performance of anti-oxidation of the materials.
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