Study On The Technology And Properties Of Nano-CeO₂ Modified FeCrSiVMn Alloy Coating Prepared By Plasma Cladding

Q235 steel is widely used in the middle trough of the traditional scraper conveyor in coal industry.Due to the poor wear resistance of Q235 steel,the middle trough of the scraper conveyor is seriously worn and scrapped,which not only affects the production efficiency of coal enterprises,but also causes greater economic losses to enterprises.Using plasma cladding technology to clad a layer of wear-resistant coating on the surface of the middle trough,not only can prolong the service life of the middle trough,but also can repair the middle trough with light wear,which can effectively solve the problems of stopping production and scrapping caused by the wear of the middle trough in coal industry.Therefore,it has important theoretical significance and engineering application value for coal production enterprises to carry out the research on the preparation technology of wear-resistant coating on the surface of Q235 steel in the middle trough of scraper conveyor and improve the mechanical properties and surface wear resistance of Q235 steel.In this paper,plasma cladding modified coating was obtained on the surface of Q235steel by plasma cladding FeCrSiVMn alloy powder.Different content of nano CeO₂(0 wt%,0.25 wt%,0.5 wt%,0.75 wt%and 1 wt%)was added into the cladding powder of FeCrSiVMn alloy by mechanical mixing.By virtue of the grain refinement and purification effect of nano CeO₂ on the cladding alloy coating,the microstructure of the coating and the comprehensive mechanical properties of the coating were further improved.The technological conditions for the preparation of the cladding modified coating were optimized by single factor test.The phase structure of the coating was analyzed by XRD.The microstructure of the coating was observed by metallographic microscope and SEM.The elements of the coating were analyzed qualitatively and quantitatively by EDS and oxygen nitrogen analyzer.The friction coefficient,hardness,wear loss and stress-strain curves of the coating were tested.The influence of preparation conditions on the microstructure and mechanical properties of the coating was investigated,The effect mechanism of rare earth oxide on grain refinement and strengthening mechanism of mechanical properties of the coating were revealed.The results show that with the increase of cladding current,ion gas,protective gas,powder feeding gas and powder feeding amount,the friction coefficient and wear weight loss of modified FeCrSiVMn alloy cladding coating firstly decrease and then increase,and the hardness firstly increases and then decreases.When the current is 175 A,the ion gas is4.5 L/min,the protective gas is 6.0 L/min,the powder feeding gas is 5.0 L/min and the powder feeding amount is 400 mg/s,the microstructure of the cladding coating is fine and uniform,and there are few cracks and porosity defects.The reciprocating friction coefficient of the cladding coating is the smallest(0.666),and the average hardness is the largest(735.12Hv).The minimum wear weight loss is 0.0122 g.The study on FeCrSiVMn alloy coating modified by nano CeO₂shows that with the increase of nano CeO₂ content,the grain in the modified coating changes from dendrite to equiaxed grain,and the arrangement of grain changes from long range order to short range disorder.When the amount of CeO₂ in the modified coating is less than 0.5 wt%,three elements of Ce,O and V in the coating are combined to form vanadate ion compounds,which are dispersed in the form of second phase particles at the grain boundary of the modified coating to produce dispersion and strengthening effect.Meanwhile,Ce element shows a good O control effect.When the addition amount of nano CeO₂ in the modified coating is greater than 0.5 wt%,the grain in the coating changes from equiaxed grain to dendritic grain,and the arrangement pattern changes from short-range disorder to long-range ordered grain.When the fluidity of the molten pool decreases,four elements of Ce,V,O and Si appear in the same position of the surface scanning energy spectrum at the same time,forming a silicate ion compound.When the addition amount of nano CeO₂ is 0.5 wt%,the modified cladding coating has the largest number of medium axial grains and the grains are short-range disordered.The modified coating has the smallest and most stable reciprocating friction coefficient,the maximum average surface hardness is 759.69 Hv,the minimum wear weight loss is 0.014 g,the maximum tensile strength is 1346 MPa,and the oxygen content is 0.023%.The cerium content is 0.04%.The overall mechanical properties of the coating are the best.