Study On Construction Of Ultra-low Frictional Interface And Tribological Properties Of Two-dimensional Black Phosphorus And Its Nanocomposites

Friction and wear is not only the main reason for high energy consumption but also key scientific and technological problem affecting the service life of mechanical equipment.Therefore,researchers have been looking for excellent lubrication materials.As a new kind of two-dimensional（2D）material,black phosphorus has special physical and chemical properties due to its unique fold structure and shows excellent tribological properties.However,the research on tribological properties of black phosphorus and its composites is still in its infancy,which greatly limits its application in mechanical lubrication.The goal of this research is to study the tribological behavior of black phosphorus and its composite materials at the friction interface,analyze the physical and chemical reactions and lubrication mechanism in the friction process,and establish the mapping relationship between the evolution of the microstructure of black phosphorus and its composite lubricating materials and friction pairs at the friction interface and tribological behavior.The main research contents of this paper are listed below.（1）2D black phosphorus was prepared by high-energy ball milling and liquid exfoliation,and dispersed into oleic acid to test its friction and wear properties.Ultra-low friction and wear were realized at the interface of stainless steel.Through the analysis of the micromorphology and physicochemical composition of the wear surface of the friction pair,combined with the reaction molecular dynamics（RMD）simulation to calculate the chemical reaction between oil molecules and black phosphorus,the tribochemical reaction pathway between black phosphorus and oil molecules is revealed.The reaction mechanism of black phosphorus inducing the degradation of oil molecules and forming self-lubricating carbon-based films is put forward,and the anti-friction and anti-wear mechanism as a lubricating additive is explained.（2）Black phosphorus dotted with silver nanoparticles（Ag/BP）composite was synthesized by a simple chemical reduction method.Friction experiments show that a very low friction coefficient and wear rate can be achieved when adding a small amount of Ag/BP nanomaterials as lubricating additives to PAO6 oil.Based on the analysis of the micromorphology and physicochemical composition of the wear marks on the friction interface,it is found that the self-lubricating carbon-based film is formed through tribochemical reaction,which leads to a very low friction coefficient and excellent wear resistance.This study confirmed the feasibility of black phosphorus dotes with silver as lubricating additive and provided a new way to expand the application of black phosphorus dotted with metal nanoparticles in the field of tribology.（3）Based on the preparation of Ag BP,Au/BP and Pd/BP composite nanomaterials were also synthesized.The tribological properties of the composites as lubricating additives were studied.Friction experimental results show that the particle size and coverage of nanometals dotted on the surface of black phosphorus have a direct impact on the tribological properties.Combined with molecular dynamics simulation,the possible role of Au nanoparticles in catalytically inducing the degradation of oil molecules to form self-lubricating carbon films was analyzed.It is found that the dotted Au nanoparticles can change the sliding mode between black phosphorus layers,to reduce friction and wear.（4）To further explore the physical or chemical reaction between black phosphorus and carbon-based film at the friction interface and clarify its influence on the tribological properties of mechanical system on the macroscale,2D black phosphorus was coated on a Si O₂ sheet as solid lubricating film,and hydrogenated DLC ball is used as the friction material.The friction experiment shows that the black phosphorus film can significantly improve the anti-wear performance of the friction pair.The analysis shows that black phosphorus can avoid the direct contact of friction pairs,and its excellent lubrication effect can effectively reduce friction and wear.With the progress of friction,under the action of friction heat and shear force,black phosphorus and its oxides can promote the chemical reaction of DLC films to form hydrogenated fullerene films,to improve the wear resistance of friction pairs.