Experimental Assessment Of The Influence Of DLC On Contact Fatigue Capability Of High-temperature Bearing Steel

The raceway and rolling elements of the aero-engine main shaft bearing undergo repeated rolling and sliding contact during operation.When the long-term operation is under extreme conditions,such as high speed,heavy load,high temperature,and high-low temperature alternation,or it faces special conditions such as broken oil and lack of oil in a short-time,and trouble pair between raceways and rolling elements causes high temperature,high temperature causes lubricant failure and degeneration of materials,eventually resulting in fatigue failure of the trouble pair contact surfaces,loss of bearing functions,and even breakdown of the work system.In order to improve the fatigue life of bearing materials and to avoid the decrease of fatigue life of bearing components due to the failure of traditional lubrication(fluid lubrication and grease lubrication),a hard coating with lubricating effect is deposited on the surface of the substrate to increase its fatigue life.Its purpose is to achieve long-term effective operation under harsh conditions.The research results of this article will provide basic reference data and evaluation methods for the development and application of aero-engine bearing materials as well as the exploration of new coating technologies and new lubrication technologies for aero-engine life extension technologies.In order to complete the fatigue tests in this article,the dynamic characteristics of the ball-disk rolling contact fatigue tester must be modified before the start of the test to ensure that the tester provides a stable and reliable working environment,and achieve the maximum Hertz contact stress from 0 to 6.8 GPa,the spindle speed from 0 to 5000 r/min,and the working environment temperature from room temperature to 220°C.At the same time,Lab VIEW is used to achieve signal acquisition and shutdown control of the tester to ensure that the tester can correctly acquire,store,and analyze signals and achieve automatic shutdown of the test.The fatigue test of 11 GCr15 bearing steel materials confirms the reliability of the ball-disk rolling contact fatigue tester.In order to study the effect of solid lubricant coating on the rolling contact fatigue life of bearing materials,a 2μm DLC self-lubricating coating is deposited on the bearing materials 8Cr4Mo4 V and 13Cr4Mo4Ni4 VA by linear ion beam hybrid magnetron sputtering.A total of 900 hours of fatigue tests are completed using a high-speed rolling contact fatigue(RCF)tester.The rolling contact fatigue and wear properties of 8Cr4Mo4 V,13Cr4Mo4Ni4VA bearing steels and DLC depositeded on 8Cr4Mo4 V and 13Cr4Mo4Ni4 VA bearing steels under mixed lubrication are studied.Electron microscopy analysis and three parameters Weibull function analysis shows that DLC films could effectively improve the rolling contact fatigue life of bearing materials by 2 to 5 times,However,it has not changed its fatigue failure mechanism。...