Microstructure and wear properties of Al2O3/TiO2 nanocomposites

Microstructure and tribological behavior for Al2O3/TiO2 nanocomposites have been studied. In order to increase the mechanical properties of alumina, TiO2 of nanometer size was added. The specimens contain 0, 5, 10,15, 20, and 25 mol % of TiO2 on alumina as remainder. Samples were hot pressed at 1500 degreesC and 25 MPa, in Ar atmosphere for 1 h. The microstructural characterization was carried out with Scanning Electron Microscope and X-ray Diffraction and EDX for chemical analysis. Fracture toughness and Vickers hardness were estimated with indentation method. Relative density was acquired using Archimedes method in toluene medium. Determination of wear behavior was carried out in a ball-on-disc tribometer, using nitride balls and distilled water at 37 degreesC for 24 h. Wear volume was calculated, and it was found the lower value at 10 mol% of TiO2. Also, the highest Vickers hardness of the nanocomposites (12.97 GPa) was achieved for this composition, but this values is lower than that monolithic alumina. The highest fracture toughness (7.15 MPa(.)m(1/2)) was obtained at 20 mol% of TiO2. It was found both intergranular and transgranular fracture mode in all the samples (monolithic alumina and nanocomposites).