Preparation And Tribological Properties Of Modified Carbon Fiber Reinforced Phosphate Coating

In view of the complexity of the working environment,the service life of metal parts of mechanical equipment has been severely challenged,and protective coating as an effective method that can improve the wear resistance of metal parts has received the attention of many scholars at home and abroad.Among them,phosphate ceramic composite coating is widely used in mechanical metal parts due to the advantages of low price and easy construction,but the phosphate ceramic composite coating has poor wear resistance due to brittleness and poor toughness.Therefore,this paper intends to carry out the preparation of modified carbon fiberreinforced phosphate coating and its tribological properties,namely,alumina,zinc oxide,zirconia as aggregate,aluminum dihydrogen phosphate(AP)as binder,and modified carbon fiber of graphene oxide as filler to prepare a phosphate ceramic composite coating with good tribological properties,and its research results will provide a better reference for the engineering application of phosphate ceramic composite coating.Firstly,graphene oxide modified carbon fibers were prepared and the preparation process was optimized,i.e.,graphene oxide modified carbon fibers(CF-GO)were prepared by electrophoretic deposition,and it was found that graphene oxide(GO)was able to deposit on the surface of carbon fibers by combining with carbon fibers(CF)through van der Waals forces.The modified carbon fibers improved their surface roughness and improved the interfacial bonding strength of the fibers and the coating.When the voltage of the electrophoretic deposition system was 30 V and the p H value was 10,a better modified density was obtained on the carbon fiber surface.The fracture morphology analysis of CFGO and CF in the cross section of the coating showed that graphene oxide could significantly improve the interfacial bonding properties between carbon fibers and the coating.The modified carbon fibers could improve the tribological properties of the phosphate ceramic composite coating more effectively compared with the unmodified carbon fibers.Next,the phosphate ceramic composite coatings were prepared by scraping and heat curing process to investigate the effect of carbon fiber content on the surface properties and tribological properties of the coatings.It was found that the roughness of the phosphate ceramic composite coating increased and then decreased with the increase of CF-GO content,and the roughness of the composite coating was maximum at 10 wt%;the hydrophobic properties of the composite coating decreased with the increase of modified carbon fiber content,but the filling of modified carbon fiber helped to improve the hardness of the composite coating.With the increase of CF-GO modified fiber content,the coefficient of friction and wear rate of the coating showed a trend of decreasing and then increasing;when the CF-GO content was 10 wt%,the coefficient of friction and wear rate of the coating were the lowest,and the corresponding coefficient of friction and wear rate were reduced by 50 %and 38 %,respectively,compared with those of the coating without the addition of carbon fiber,which indicated that the appropriate amount of modified carbon fiber could improve the tribological properties of the phosphate ceramic This indicates that the appropriate amount of modified carbon fiber can improve the tribological performance of the phosphate ceramic coating.Finally,a study of the factors affecting the tribological properties of the phosphate ceramic composite coatings containing 10 wt% CF-GO modified fibers under different operating conditions was carried out.With the increase of temperature,it was found that the influence of temperature on the friction coefficient of the composite coating was small,but its friction coefficient showed large fluctuations;the maximum depth of wear marks and wear rate of the composite coating were positively correlated with the service temperature,and the higher service temperature produced a larger wear rate,which might be due to the synergistic effect of thermal stress and mechanical stress between the coating and the counter friction sub at high temperature,which in turn reduced the wear resistance of the coating.Under the sliding rate of 10 mm/s,the friction coefficient and wear rate of the phosphate ceramic composite coating are positively correlated with the normal load;under the normal load of 10 N,the friction coefficient of the composite coating remains the same as the sliding rate increases,but the wear rate shows an increasing trend,which indicates that the normal load and sliding rate have a significant effect on the tribological performance of the phosphate ceramic composite coating This indicates that the normal load and sliding rate have a significant effect on the tribological performance of phosphate ceramic composite coatings.The above results provide a good technical insight to broaden the engineering application of phosphate coatings.