| Aero-engine spindle bearings are one of the most important parts of the engine,and its performance is directly related to the performance of aeroengine.A kind of aeroengine No.3A fulcrum bearing failure due to wear and tear.Lubricating oil mixed with impurities leads to bearing cage wear bearing rings guide surface when the bearing running.The most serious situation is the guide surface is polished while the bearing runs less than ten hours.Surface engineering technology applied to the aircraft bearings,for improving the performance and service life of bearings has an irreparable role.TiN thin films deposited on the surface of aircraft bearing guide surface by physical vapor deposition can strengthen the surface friction performance of bearing guide surface,and improve wear resistance and service life of aircraft bearing.Therefore,it is of great significance to study the preparation technology and process of TiN thin film,and improve the comprehensive performance of the film,and realize the application of TiN film on aeroengine bearing.In this paper,the preparation technology,performance characterization method and preparation process optimization of TiN thin film were studied.The bearing protection tools were designed and the coating turntable system was improved designed.The preparation and application of TiN film on the surface of aircraft bearing were realized,and the coated bearing was tested by bench test.TiN thin film was prepared using multi-arc ion plating equipment.There are many factors influencing the performance of TiN thin film.The process parameters such as substrate bias voltage,target current,gas partial pressure and deposition temperature are the most important factors.The orthogonal test of four factors and three levels was designed to analyze the influence of various process factors on the performance of TiN thin film,and then the combination of process parameters was optimized.The process optimization test results showed that the deposited TiN thin films had excellent comprehensive properties when the substrate bias voltage was 80V,the target current was 70A,the deposition temperature was 300℃ and the N2 gas flow rate was 400 SCCM.TiN thin film had a microhardness of more than 2200HK0.025,with an average of 2264.03HK0.025;the film binding force was above 60N,up to 70N,the average was 66.13N;the friction coefficient was less than 0.6,the average was 0.5699;the results of XRD showed that the film had a strong(111)crystal orientation,which indicated the wear resistance,hardness and other performance was excellent;the film thickness was moderate,between 2μm-4.5μm;the three-dimensional white light interferometer was used to measure the wear marks and the results showed that TiN thin film had good wear resistance.In order to realize the good deposition of TN film on the guide surface of aircraft bearing,protective tools were designed for the bearing.Aircraft bearing was a high-precision parts,requiring the needed to deposit TiN film parts can not leak,no deposition of the film parts must not be coated.The guide surface and the raceway were connected so that the raceway retaining ring was designed to fit the the raceway arc to ensure that the retaining ring can closely shelter the raceway.As the guide surface was curved,pre-test found that the film thickness was not uniform.In order to make the TiN film thickness uniformity,the equipment workpiece turntable was made an improved design.Change the movement of bearing in the vacuum chamber by designing planetary gear train,so that the bearing can revolve around the central wheel,but also rotate around its own axis.Design center gear one,the dividing circle diameter D1=333mm,modulus m=3;planetary gears five,the dividing circle diameter D2=66mm,modulus m=3.The kinematic analysis of the bearing coating workpiece turret was carried out by using the Adams multi-body dynamic simulation software.The results showed that the movement of the coating turret reached the expected target,and bearing can revolute and rotate.The simulation calculated values of the planetary gear ratio were consistent with the theoretical calculated values.A bench test was carried out on aircraft engine No.3A fulcrum bearing coated with TiN thin film using spindle bearing cantilever tester of Harbin Bearing Group Corp..The surface of the coated bearing was analyzed after 50-hour examination and verification,and the results showed TiN thin film surface condition was intact,the bearing could continue to use.In summary,preparing TiN thin films on aeroengine bearings by using physical vapor deposition can help solve the bearing guide surface wear problem,and can help improve the service life of bearings. |
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