Basic Research On The Application Of Ion Implantation In Cylindrical Roller Bearings

Cylindrical roller bearings are widely used in the aerospace field and are important components of aero-engine rotor systems.Due to the harsh working environment,they are prone to failure.For cylindrical roller bearings of aero-engine main shaft bearings,the key to improving working life and preventing early failure is to improve the performance.At present,surface strengthening technology is an important method to improve the comprehensive performance of the surface of the material,and ion implantation does not change the structural size of the material.Compared with other methods,it is the most suitable surface strengthening technology to improve the performance of cylindrical roller bearings.Therefore,in this paper,the representative material of the cylindrical roller bearing Cr4Mo4 V steel is ion implanted,and a modified layer of ion implantation was formed on the surface to characterize its basic properties.The treated sample and the rollers of a certain type of cylindrical roller bearing form a friction pair,and the line contact friction and wear experiment is carried out on the CETR friction and wear tester.Combining the analysis of friction coefficient and wear scar characteristics,the friction wear of different ion implantation parameters is studied,and then reveal the mechanism of ion implantation to improve the friction and wear performance of cylindrical roller bearing.The conclusions are as follows:(1)Basic properties of ion implantation modified layerThe ion implantation layer has a certain thickness,and different elements can be implanted.The corresponding element peaks can be found,indicating that the implantation effect is good.In the Ti-injected sample,the Ti element exists in the form of titanium oxide and elemental substance;In the N-injected sample,a chromium nitride phase is generated,and the unreacted nitrogen atom solid-solution strengthens the matrix,which exists as interstitial atoms;The Ti+N sample,there are chromium nitride phase and interstitial nitrogen atoms in the sample,as well as titanium oxide phase and titanium nitride phase.the nano-hardness and micro-hardness of the Ti + N sample are the largest,followed by the N sample and the Ti sample again,and the matrix sample has the smallest hardness.(2)The wear mechanism of samples with different injected elementsFor the samples under different element injection conditions,the friction coefficient undergoes three stages of initial,rising(fluctuation)and stability with the cycle time.Combined with the basic performance analysis of the ion implantation layer,the wear is relatively serious.The wear mechanism is oxidative wear,adhesive wear and abrasive wear;the titanium injection phase is produced in the Ti-injected sample,which can play a lubricating role and inhibit development of abrasive wear;There is a gap solid solution in the N sample,the surface hardness is greatly strengthened,and the adhesive wear is reduced;the presence of titanium oxide,titanium nitride and interstitial solid solution in the Ti + N sample increases the hardness and improves Lubrication performance,abrasive wear and adhesive wear are all reduced.(3)The wear mechanism of samples with different injection energy and injection doseAs the injection energy rises,the initial friction coefficient of the Ti sample decreases and the cycle of maintaining the initial friction coefficient increases,and the degree of wear gradually decreases.With the increase of the injection dose,the friction coefficient of the Tiinjected sample changes but is not obvious.The wear mechanism of Ti-injected specimens is mainly adhesive wear and oxidative wear.Note that as the injection energy rises,the initial friction coefficient of the N-injection sample decreases and the cycle of maintaining the initial friction coefficient increases.The increase of the injection dose also reduced the initial friction coefficient of the N-injected sample and improved the wear performance.The wear mechanism of N-injected specimens is mainly abrasive wear and oxidative wear.(4)Mechanism analysis of ion implantation to improve friction and wear performanceAfter ion implantation,an ion implantation layer is formed on the surface of the sample,and a large number of new phases are generated and accompanied by solid solution strengthening.Some phases improve the lubricating performance,and some phase strengthening matrix improves the surface hardness of the sample,avoiding a lot of plastic deformation.New phases the formation of improves the lubrication characteristics of the surface,thereby weakening the adhesion wear and abrasive wear,and the friction coefficient are reduced.