Wear behaviour of Al2O3-Mo and Al2O3-Nb composites

The wear behaviour of two Al2O3-Mo and two Al2O3-Nb particulate composites with different Mo particle size and Nb contents, respectively, obtained by hot-pressing, was evaluated. The inverted pin-on-disc tests were performed by making ceramic pins slide against WC discs at different loads with a constant sliding speed and sliding distance. When the load increased the specific wear of alumina-molybdenum composites increased dramatically while the wear of alumina-niobium material remained almost constant inspite of the increase of the applied load. On the other hand, the wear of the WC discs was very low against Al2O3-Mo but extremely high against Al2O3-Nb composites. It was also found that the friction coefficient strongly depends on the applied load but weakly on the pin material. The lower the load the higher the friction. A possible explanation of the wear mechanisms is proposed.