Abstract: Aiming at the problem that homogeneous self-lubricating ceramic cutting tool materials are not available to possess rational combination of antifriction and antiwear properties, a graded self-lubricating ceramic cutting tool material is developed by applying the design concept of functionally graded materials. The new type of self-lubricating cutting tool material is characterized by the solid lubricant’s decreasing distribution from the outer layers to the inner layers and the residual compressive stresses existing in the surface layers. A multicomponent distribution model is proposed. According to the model, Al2O3/TiC/CaF2 graded self-lubricating ceramic cutting tool material is compositionally designed and then is prepared by using the process of laminated padding and hot press in vacuum. The microstructure of the graded self-lubricating ceramic cutting tool material changes in accordance with the compositional distribution. Residual compressive stresses are formed in the surface layers. Compared with the corresponding homogeneous material, flexural strength, hardness and fracture toughness of the Al2O3/TiC/CaF2 graded self-lubricating ceramic cutting tool material are increased by 21%, 16% and 5.9%, respectively. The flexural strength is increased mainly because CaF2 in the material decreases from the surface layers to the middle layer. The improvement in the hardness and fracture toughness is attributed to the residual compressive stresses in the surface layers. Dry cutting tests are carried out on 45 steel with Al2O3/TiC/CaF2 graded self-lubricating ceramic cutting tool and the corresponding homogeneous cutting tool. Results show that wear resistance of the graded cutting tool is superior to that of the homogeneous cutting tool.

Key words: graded self-lubricating;ceramic cutting tool material;solid lubricant;mechanical property;microstructure