Wear-resistant ultra-fine-grained ceramics

We have studied the effect of grain refinement in the sliding-wear resistance of (alpha)-Al2O3/(beta)-Al2TiO5 polycrystalline ceramics. In order to obtain dense, ultra-fine-grained ceramics, we start with a single-phase, metastable solid-solution nanopowder (Ti-doped Al2O3), which is subsequently spark-plasma sintered. The resulting 400 nm grain size, fully dense (alpha)-Al2O3/(beta)-Al2TiO5 ceramic has significantly improved wear resistance over its 2.2 (mu)m grain size counterpart, and also over a 4 (mu)m grain size pure (alpha)-Al2O3. A mechanistic model by Lawn and co-workers is used to analyze these wear results, and to provide guidelines for the design and fabrication of highly wear-resistant nanoceramics. This may have important implications because ceramics are being used increasingly in contact-mechanical and tribological applications.