Effect of gradient design on the mechanical property and friction performance of nano self-lubricating ceramic cutting tool material

A gradient nano self-lubricating ceramic cutting tool material was prepared by vacuum hot-pressing sintering technique. The composition of each layer is designed in a gradient so that the nano-sized solid lubricant content is gradually reduced from the surface to the center, and residual compressive stresses are formed in the tool surface. The components and microstructure of the prepared ceramic tools showed gradient changes, with clear and well-bonded interfaces between the gradient layers. Compared with the mechanical properties of homogeneous tool, the flexural strength, fracture toughness, and hardness of this ceramic tool were increased by 74.0%, 3.9%, and 5.0%, respectively. The gradient design had little effect on the friction coefficient, but the improved mechanical properties and the presence of residual compressive stresses in the surface layer improved the wear resistance of the tool. The higher the friction speed and load, the more effectively the gradient design will improve the wear rate.