Abstract:

A novel laminated Al₂O₃/TiC/CaF₂-Al₂O₃/TiC sandwich ceramic composite was fabricated through cold pressing and sintering to achieve better anti-wear performance, such as low friction coefficient and low wear rate. Al₂O₃/TiC/CaF₂ and Al₂O₃/TiC composites were alternatively built layer-by-layer to obtain a sandwich structure. Solid lubricant CaF₂ was added evenly into the Al₂O₃/TiC/CaF₂ layer to reduce the friction and wear. Al₂O₃/TiC ceramic was also cold pressed and sintered for comparison. Friction analysis of the two ceramics was then conducted via a wear-and-tear machine. Worn surface and surface compositions were examined by scanning electron microscopy and energy dispersion spectrum, respectively. Results showed that the laminated Al₂O₃/TiC/CaF₂-Al₂O₃/TiC sandwich ceramic composite has lower friction coefficient and lower wear rate than those of Al₂O₃/TiC ceramic alone because of the addition of CaF₂ into the laminated Al₂O₃/TiC/CaF₂-Al₂O₃/TiC sandwich ceramic composite. Under the friction load, the tiny CaF₂ particles were scraped from the Al₂O₃/TiC/CaF₂ layer and spread on friction pairs before falling off into micropits. This process formed a smooth, self-lubricating film, which led to better anti-wear properties. Adhesive wear is the main wear mechanism of Al₂O₃/TiC/CaF₂ layer and abrasive wear is the main wear mechanism of Al₂O₃/TiC layer.

Key words: Friction and wear characteristics, Wear property, Ceramic-matrix compos­ites, Layer manufacture, Surface appearance, Sliding