Preparation And Friction Properties Of MoS₂ Coating On 15-5PH Stainless Steel Surface

In the field of aerospace manufacturing,many parts and components undergo friction and wear during service,resulting in failure.In order to suppress this problem and prolong the service life,adding bushings at the bearing position has become a common solution in this field.Compared with the traditional thermal expansion and contraction bushing method,the cold drawing method can greatly reduce the installation time,accurately control the amount of extrusion,and effectively inhibit the entry of water vapor.Therefore,it is more effective in improving production efficiency,reducing corrosion,and extending fatigue life.Obvious advantage.However,in the assembly process of the cold drawing method,the mandrel is likely to cause axial tensile damage to the bushing,so it is necessary to prepare a coating with good self-lubricity on the inner surface of the bushing.At present,in the coating preparation process,uneven coating thickness,poor bonding force,and short service life are still bottlenecks restricting the development of cold drawn bushings in the country.In this paper,based on a certain type of helicopter bushing material(15-5PH stainless steel),molybdenum disulfide(MoS₂)is used as the main component of the self-lubricating layer,and the coating is prepared by spraying.The influence of various process parameters on the quality of the coating is studied,and the process methods and technical paths to improve the uniformity,bonding force and service life of the coating are proposed.Finally,the self-lubricating coating meeting the installation conditions of cold drawing method is prepared by rotary spraying on the inner surface of the bushing for a helicopter,which provides important theoretical and technical support in engineering application.The main research contents are as follows:First,based on the preparation of MoS₂coating on the 15-5PH stainless steel plane,the L9(3⁴)orthogonal experiment design method was used to optimize the spraying parameters.The range analysis found that the spraying pressure was 0.3MPa,the spraying distance was 150 mm,and the spraying time was 8s.The spraying quality is the best.Then,the samples are prepared and processed into substrates with different roughness,and MoS₂coating is sprayed.Through macro morphology,micro morphology,friction and wear test and EDS test and analysis,it is concluded that the coating particle distribution on the substrate with roughness Ra0.4?m is the best and the bonding strength with the substrate is high.The service life of the coating is obviously affected by the surface roughness of 15-5PH substrate.The wear failure time of the coating on the surface of Ra1.6?m,Ra0.4?m and Ra0.05?m are 5430s,7982s and 950s,respectively.The coating on the substrate roughness Ra0.4?m shows the best self-lubricating performance.Furthermore,the pre-coating formula is optimized and designed,and the bonding force between the self-lubricating coating and the substrate and the service life of the coating are improved by adding epoxy resin(E54).The test found that the coating particles with 2.5%resin content become tighter,and the strength and hardness of the coating are improved.As the resin content increases,the service life first increases and then decreases.When the resin content is 0%,1.5%,2%,2.5%,3%,3.5%,the service life of the coating is 2266s,5209s,6664s,13234s,1239s,684s,respectively.Finally,on the basis of the previous work,the coating is prepared on the curved surface of the 15-5PH stainless steel bushing inner surface,and the coating preparation device is designed by itself.The spraying parameters,substrate roughness and epoxy resin bonding system formula are optimized in the early stage.On the basis of,a curved coating on the inner surface of the bushing was prepared,and the bushing was installed according to the installation conditions in actual applications.The coating reached the requirements for the cold extrusion method to install the bushing,and finally realized the engineering application.