Fabrication of surface-carbonated boron nitride nanosheets and their application as water-based lubrication additives

As a typical two-dimensional layered material, hexagonal boron nitride nanosheets (BNNSs) have high mechanical strength, good conductivity, and excellent lubrication performance, which have great potential as solid nano lubricant additives in tribology. When BNNS is used as a water-based or oil-based lubricant additive, its inherent chemical inertness and poor dispersion stability make it difficult to achieve optimal anti-friction and anti-wear performance. In this paper, a simple and efficient preparation method for obtaining hexagonal boron nitride nanosheets (C-HPC-BNNSs) with surface carbonization modification and excellent dispersion stability in water-based lubricants was proposed. Using hydroxypropyl cellulose (HPC) as a modifier, a wet ball milling process combined with high-temperature carbonization treatment effectively reduced the thickness of BNNSs while uniformly modifying N-doped carbon layers on the surface of the nanosheets. Benefit from the smaller layer thickness of C-HPC-BNNSs, they exhibit excellent dispersion stability in the water-glycol solution and can maintain no significant agglomeration behavior for up to 30 days, which is the basis for the excellent lubrication performance of lubricant systems. In addition, the N-doped carbon layer modified on the surface is beneficial for enhancing the hydrophilicity of BNNSs and synergistically enhances the tribological properties of the material with BNNSs. The test results of the four-ball friction tester show that compared with the pure water-glycol solution and the water-glycol system with added C-HPC-BNNSs, the friction coefficient (COF) and wear volume of the system with added C-HPC-BNNSs could be as low as 0.095 and 1.99 × 10⁻⁴ mm³, respectively. This work has positive significance for the preparation, surface modification, and tribological application expansion of two-dimensional layered material BNNSs, which is conducive to further understanding the relationship between.