Reseaerch On The Tribological Properties Of Nitride Coating On High Temperature Bearing Under Oil/oil-free Lubrication

With the rapid development of aerospace technology,solid lubrication coatings have played an important role in meeting the requirements of long life,high reliability and high precision for space mechanism movable bearings.Spherical joint sliding bearing is often used in low-speed space mechanism,and ball bearing or roller bearing is also used in medium-low speed space mechanism.The solid coating mainly works under the harsh working conditions such as oil and grease that cannot be met,and also needs to work in cooperation with oil and grease when the temperature and rotation speed are in the normal range.Based on the surface lubrication design of rolling bearing and sliding bearing,this paper studies the abrasion resistance of nitride solid coating under oil lubrication,as well as the self-lubrication properties and bearing capacity at high temperature,providing the theory instruction for surface lubrication design of bearings under complex service conditions such as variable temperature and load.First of all,in order to complete the oil lubrication test of nitride coating on rolling bearing,this paper selected high temperature angular contact ball bearing 71910 C used in an aerospace mechanism and built a test system for rolling bearing oil lubrication.The experimental scheme of the ball bearing is selected by the quasi-dynamics theory calculation.The stress distribution of the coating interface and the subsurface layer of the matrix in the contact area of the bearing raceway is calculated by using the model of EHL and elastic contact.Finally,the solid-liquid composite lubrication experiment of the ball bearing 71910 C was completed through the oil lubrication test system,the abrasion resistance of nitride coating was judged by analyzing the wear condition of the coating in the bearing contact area.In order to study the comprehensive performance of the coating from oil-lubricated at common temperature to oil-free high temperature,the same type of bearing 71910 C was selected,the corresponding high-temperature test equipment was designed and the oil-free test of nitride coating on the surface of ball bearing at 500? was completed on the high-temperature testbed.The dynamic characteristics of bearing and the stress state of surface nitride coating were obtained through quasi-dynamics and thermoelastic contact model analysis.By combining the results of testing friction torque and surface morphology,the high temperature friction and wear performance of nitride coating on rolling bearing was analyzed and judged.Finally,In order to further judge the high temperature friction performance of nitride coating on sliding bearing,the joint bearing used in an aerospace mechanism was selected as the research.Firstly,the spherical bearing coordinated contact model is used to complete the prediction analysis of the bearing characteristics and friction torque of the joint bearing.Secondly,the high temperature friction torque performance test of multiple sets of different types of joint bearings containing nitride films was completed through the testbed.Combined with the friction torque calculation model,the fluctuation and development rules of the bearing friction process were analyzed by comparison,and the friction performance of joint bearing with nitride coating under different sizes and working conditions was judged.The high-temperature lubrication performance and anti-wear ability of nitride coating on bearing were verified.