Sliding interface characteristics and self-lubrication mechanism of B4C-Al2O3 4 C-Al 2 O 3 composite ceramics

B4C 4 C ceramics are an important structural material in the field of engineering. However, B4C 4 C ceramics have two fatal drawbacks: low fracture toughness and high friction coefficient. The design strategy and tribological mechanism of B4C 4 C ceramics with low friction are studied in this paper. The results show that the incorporation of Al2O3 2 O 3 as a second phase can not only increase the fracture toughness but also reduce the friction coefficient of B4C 4 C ceramics, achieving the self-lubrication of B4C 4 C ceramics. The low friction design strategy of B4C 4 C ceramics is realized by incorporating a second phase of Al2O3 2 O 3 to change the physical characteristic of the sliding surface. The sliding interface characteristic of in situ formed surface texture with an appropriate proportion of valleys in the sliding process is the most important factor for the improved tribological properties of B4C-Al2O3 4 C-Al 2 O 3 composite ceramics. As the amount of Al2O3 2 O 3 incorporated is 30 wt%, B4C-Al2O3 4 C-Al 2 O 3 composite ceramics have the most appropriate proportion of valleys in the surface texture, thus exhibiting the lowest friction coefficient. The clean phase boundary makes the bonding between B4C 4 C and Al2O3 2 O 3 grains firm, which is the key to achieving the function of the surface texture formed in situ. B4C-Al2O3 4 C-Al 2 O 3 composite ceramics with both high fracture toughness and low friction coefficient will open a wider range of applications.