Green waterborne PAI-graphite bonded solid-lubricating coatings: Promising lubricating materials with robust mechanical and tribological properties.

• Waterborne PAI-graphite coatings are green lubricating materials. • Waterborne PAI-graphite coatings exhibit superior mechanical and tribological properties. • Tribological mechanisms of waterborne coatings were systematically investigated. • Tribological properties of waterborne coatings under different experimental conditions were explored. The purpose of this work is to fabricate novel green waterborne PAI-graphite bonded solid-lubricating coatings (BSLCs) with superior mechanical and tribological properties so as to replace the reported organic-solvent BSLCs to some extent, and further investigate the lubricating mechanisms. The work indicates that, the preparation of the waterborne PAI-graphite BSLCs have greatly reduced the utilization rate of organic solvents (without the usage of organic solvent). The basic physicochemical properties of the coatings have reached the corresponding level of the organic-solvent BSLCs. When the mass ratio of waterborne PAI resin and graphite is 1.2, the waterborne graphite-based BSLCs exhibit superior mechanical and tribological properties, which are comparable to those of the reported organic-solvent BSLCs. The variation of tribological properties of the waterborne PAI-graphite coatings under diversified applied loads and reciprocating frequencies were explored systematically for the sake of the better understanding of environmental adaptability of the waterborne PAI-graphite BSLCs. [ABSTRACT FROM AUTHOR]