Research On The Microstructure And Performance Of Ni-W Composite Coatings Based On Ti₃C₂T_x Nanosheet

Surface treatment technology is widely used in many fields of national economic production and life because it can effectively protect the failure behavior of metal materials.Direct current deposition technology has become a very important surface treatment technology with its advantages of simple operation,low cost and excellent performance.As an important new type of replace chromium coating,Ni-W alloy coating has excellent mechanical properties,tribological properties and corrosion resistance.However,with the development of science and technology and the increasingly harsh service environment of materials,the traditional Ni-W alloy coating has been difficult to meet the special service conditions.By transplanting the excellent properties of the second phase particles into the coating to prepare Ni-W-second phase particles composite coating,it has become an important way to improve the microstructure of the coating,improve the properties of the coating,and meet the requirements of practical use.In recent years,Ti₃C₂T_x,a two-dimensional material with high strength,high conductivity,excellent mechanical properties and wear reduction lubrication characteristics,has attracted extensive attention of researchers.Based on this,this paper for the first time tried to introduce two-dimensional material Ti₃C₂T_x into Ni-W alloy coating,and prepared a novel Ni-W-Ti₃C₂T_xcomposite coating by co-deposition technology.The effects of DC deposition process parameters and composite surface modification treatment on the microstructure and properties of Ni-W-Ti₃C₂T_x composite coating were lucubrated and the mechanism of behavior was also analyzed.Research indicates:（1）The addition of Ti₃C₂T_x has an important effect on the microstructure and properties of the composite coating:The effects of different Ti₃C₂T_x addition on the microstructure,crystal structure,hardness,tribological properties and corrosion resistance of the composite coating were studied.When the addition amount of Ti₃C₂T_x was 20 mg/L,the surface of the composite coating was smooth and compact,the preferred orientation of Ni（111）surface was the most obvious,and the hardness of the composite coating was the highest.The friction coefficient and wear rate are the lowest,the self-corrosion current density is the lowest and the corresponding impedance arc radius is the largest.The layered structure of Ti₃C₂T_x reduces the direct contact between the friction pair and the matrix during the friction process,and the preferred orientation of Ni（111）surface and the appropriate grain size improve the corrosion resistance.（2）The effects of different current densities on the microstructure,structure and properties of the composite coatings were studied on the basis of the optimal addition of Ti₃C₂T_x 20 mg/L.The deposition efficiency of composite coating increases with the increase of current density,but cracks appear when the current density is higher.When the current density is 5 A/dm²,the hardness reaches the maximum value,the tribological properties and surface quality are the best,and the corrosion resistance of the composite coatings is greatly improved compared with other current densities.（3）The influence of p H value of different bath on the composite coating was studied on the basis of the optimal addition of Ti₃C₂T_x 20 mg/L and the optimal current density of 5 A/dm².When the p H value is low,the deposition efficiency of the composite coating is very low and a lot of cracks appear on the surface due to internal stress.The grain size of the composite coating decreases with the increase of p H value.When p H value is 9,the composite coating has the best surface quality,hardness,wear resistance and corrosion resistance.（4）The optimum electrodeposition process is as follows:the Ti₃C₂T_x addition amount is20 mg/L,the optimum current density is 5 A/dm² and the p H value of bath is 9.On this basis,the effects of electrodeposition and ultrasonic shot peening on the microstructure,microstructure and properties of the matrix were studied.Ultrasonic shot peening improved the surface hardness and roughness of 45^#steel,and grain refinement effect is achieved,but the corrosion products of Fe have no passivation effect,and the corrosion resistance of composite coating decreases.After electrodeposition,ultrasonic shot peening can impact the spherical particles of the composite coating into a plane shape,and the grain size of the composite coating is refined due to plastic deformation.The hardness of the composite coating is significantly improved,and the corrosion resistance is also improved.