The New Al <sub> 2 </ Sub> The O <sub> 3 </ Sub>-based Ceramic Cutting Tool Material On The Tribological Behavior

Ceramics have intrinsic characteristics, such as: high melting point, high hardness, good chemical inertness and high wear resistance, which make them promising candidates for wear resistance components. Nowadays the advanced ceramics are widely used as wear-resistance material especially in the tribological field. In this study, several kinds of Al₂O₃-based ceramic tool materials consisted of different additives (i.e. Al₂O₃, Al₂O₃/TiC, Al₂O₃/(W,Ti)C, Al₂O₃/Ti(C,N), and Al₂O₃/SiC_w) made by Shandong University were chosen, researches on the tribological characteristics of these ceramics at different conditions were carried out. The stress and its distribution during friction and wear processes were calculated. The wear mechanisms were studied.Dry friction and wear tests at room temperature were conducted with a MRH-3 high-speed ring-block tribometer. Results showed that the friction coefficient and the wear rates of Al₂O₃-based ceramics decreased with the increase of the sliding speed, and the wear rates increased with the increase of the applied load during the stable wear stage. The friction coefficient and the wear rate of pure Al₂O₃ ceramic were higher than most of Al₂O₃-based ceramics with reinforcing and toughening additives under the same conditions. The friction coefficient and the wear rates sliding against hardened were reduced compared with that of sliding against cemented carbide.Finite element model was established by ANSYS software to get the stress and its distribution during high-speed ring-block wear processes. Results showed that there is a great difference of the maximum of main and shear stress for the Al₂O₃-based ceramics with different additives. The maximum of main stress is located at the center of sliding couple, while the maximum of shear stress at the outside of sliding couple. The value ofthe stress increases with the increase of applied load, and the sliding speed just has little effect on the stresses.Hardness, elastic modulus, and fracture toughness were found to have a profound effect on the wear resistance of the Al₂O₃-based ceramic materials. The wear rates of the Al₂O₃-based ceramics increased with the increase of the ratio of elastic modulus and hardness, and decreased with the increase of fracture toughness, brasive wear was found to be the predominant wear mechanism for the Al₂O₃-based ceramics with reinforcing and toughening additives. While the mechanisms responsible for the wear for the pure Al2O3 were determined to be brittle fracture and grain delamination due to its poor mechanical properties.