Friction and Wear Behavior of TiB2 Reinforced Al2O3 Ceramic Cutting Tool in Dry Cutting of Hardened Steel at High Speed

Dry cutting tests at high speed were carried out with respect to hardened steel and TiB_2 reinforced Al_2O_3 ceramic cutting tools. Thus the friction and wear of the tool was reduced by in-situ forming an oxide film on the tool rake face, making use of the tribochemical reaction at high cutting temperature. The effect of the tool composition on the friction and wear behavior was investigated,and the morphologies of the rake face and rear face of the tool cutting the steel in air and nitrogen were observed on a scanning electron microscope. It was found that the Al_2O_3/TiB_2 tool was dominated by adhesive and abrasive wear in low speed dry cutting; while in high speed dry cutting,the tool was characterized by oxidation wear. An oxide layer of TiO_2 was formed by way of the oxidation of the reinforcing agent TiB_2 at a very much high cutting temperature, which contributed to greatly reducing the friction coefficient and increasing the antiwear life of the tool.Such a friction-reducing and antiwear behavior of the oxide layer was enhanced with increasing content of TiB_2 in the tool composite. However,the tool showed a relatively poorer wear resistance in N_2 than in air, because N_2 acted to retard the oxidation of the TiB_2 and the formation of the oxide layer on the tool rake face.