Friction and wear characteristics of graphite
Due to the anisotropy of the crystal structure of graphite, the mechanical properties of graphite crystals also have
Remarkable directionality, showing different mechanical properties and Tribological Characteristics in different directions: graphite crystal
(001) base surface has a significant sliding system, which makes graphite form a good lubricity; Adjacent basal plane of graphite crystal
The binding force between carbon atoms is more than 100 times smaller than that between carbon atoms in the same base plane (IL3]; In single crystal graphite
The hardness value measured under a load of 0.1N on the crystal is about 4.8 × 107 n / m2, which is about the shear strength in the basal plane direction
50 times 114 degrees]; The friction coefficient of the prism of graphite crystal under low load (& lt; 40rag) can be as high as
0.3, and the friction coefficient perpendicular to the graphite prism is about 30 times fl of the friction coefficient between the base surfaces ". Therefore, graphite
It is a kind of material with both lubricity and high abrasiveness.
During the friction between graphite and metal, the graphite crystals undergo interlayer cleavage, and the broken graphite scales separated are easy
And adheres to the surface of the counter grinding metal to form a thin layer transfer film. Because graphite has a layered crystal structure, graphite is crystalline
The surface is composed of cleavage surface and prism. The cleavage surface is a low-energy surface with low adhesion. Although the prism is active
Higher, but it can interact with water and oxygen in the atmosphere to form a surface with different oxygen-containing groups, so graphite turns
The film transfer exhibited a low friction behavior 116]. When the transfer film is completely formed, the grinding process between graphite and metal is
It becomes the friction between graphite and graphite, the friction coefficient will be significantly reduced, and the wear speed of the grinding metal will also be increased
And gradually decreases to a constant value.