A Study Of Temperature Effects On Diamond Nanoscale Wear

In the process of nano-scale grinding of single crystal diamond,the local temperature variation of the abrasive particles seriously affects the service life of the props and the surface quality of the workpiece.At present,the influence of temperature on the wear rate of single crystal nanoscale diamond is not clear.In this paper,molecular dynamics(MD)simulation method is used to calculate the wear amount of abrasive particles in the process of sliding,considering the change of the overall temperature of the system and the temperature of the local contact area,and the influence of the temperature in the process of abrasive wear on the wear rate is discussed.In addition,the effect of load on temperature change and wear rate of local contact area during wear is considered.The limitation of the classical Achard model in calculating the wear amount of microstructure is discussed.The specific research contents are as follows:(1)The molecular dynamics model of single-crystal diamond was established by molecular dynamics simulation method and the wear process was simulated.Different initial temperatures of 300K?900K were set in the system to analyze the influence of the overall temperature of the system and the temperature change of local contact area on the nanoscale diamond wear process.According to the calculation of the thermal velocity of the local contact area between the abrasive particles and the workpiece surface,the temperature of the local contact area during the wear process is calculated.The change of atomic distribution and wear height in each temperature model was observed by visual software.By analyzing the wear process from the whole temperature of the system and the local temperature change of the friction contact surface,the relationship between the temperature and the number of atoms lost and the wear height in the wear process is discussed.And it is considered that the hardness of single crystal diamond decreases and the wear rate is accelerated when the temperature rises.(2)The influence of different loads on the temperature change and wear rate in the local contact area of nano-scale diamond wear process is analyzed under the same system temperature.Different loads of 12 nN?72nN were applied to the diamond abrasive particles.By analyzing the local temperature change and wear height of the worn surface during the wear process,the results showed that under the same system temperature,the influence of changing load size on the maximum temperature of the worn surface contact area was not obvious,but the load size had a great influence on the wear amount.The larger the normal load of the abrasive surface,the higher the wear rate was.(3)The limitations of the classical Achard's law in calculating the wear amount of microstructure are discussed.According to the classical Achard's law calculation formula,the relationship between wear height of abrasive particles and sliding distance of abrasive particles is solved theoretically,and the MD simulation results under different temperatures and loads are fitted according to the theoretical solution obtained.For the comparison and simulation results,compared with the simulation results of MD under different system temperatures and loads,the curve fitted by Achard's law calculation formula has a larger difference in wear amount in the initial stage,and the difference in wear amount between the fitted curves varies with the initial temperature of the system.Therefore,we believe that Achard's law is no longer applicable to the calculation of wear amount at the nanoscale of single crystal diamond considering temperature change.