Research On Pulse Electroforming Of Ni-TiN Nanocomposite Deposits In An Ultrasonic Field

Metal matrix composite coating is a new kind of composite material with special functions,which not only has excellent properties of matrix metal,but also the special characteristics of dispersed particles.In this paper,the Ni-TiN composite coating on the surface of T8 steel was studied.Due to the introduction of hard phase TiN nanoparticles,the structure and properties of the coatings will change.The influence of process parameters on the plating rate is studied and the most optimal formulation of plating optimum formulas is provided in this paper.On this foundation,the Ni-TiN composite coating is prepared by appending TiN nanoparticles and the compound surfactant,and stirring with ultrasonic field.The influence of the process parameters such as the content of TiN nanoparticles,ultrasonic power and the content of anionic surfactant on the microhardness of the coating are also discussed.The experimental results show that when the content of nickel sulfate is 240g/L,the current density is 0.6 A/dm2,the concentration of TiN is 6 g/L,the duty cycle is 50%,the bath temperature is 50℃,and the ultrasonic power is 180 W,the pH value is 4,the plating bath can get a higher plating speed.For this prepared Ni-TiN composite coating,scanning electron microscopy was used to observe the surface morphology of the coatings before and after heat treatment,the phase composition of the coating was measured by X ray diffractometer,and the porosity of the coating was measured by etching method.The microhardness of Ni-TiN composite coating was improved by heat treatment,and the optimum heat treatment temperature was also optimized.The results show that the wear resistance of Ni-TiN composite layer after heat treatment is related to the hardness change of the composite layer after heat treatment.When the heat treatment temperature is400℃×0.8 h,and the content of nano particles is about 6 g/L,the micro hardness of the deposited Ni-TiN composite coating is about 732 HV,and it is up to 981 HV after heat treatment,and the wear resistance of the composite coating is the best,the friction coefficient is small and it varies little with time.When the heat treatment is 400℃× 0.8 h,the amorphous state will change to the crystalline state,and finally change into equilibrium phase of Ni,NiO and TiN.It can be seen from the XRD diffraction analysis that the TiN particles remain constant during this process.Scanning electron microscope observation shows that a largenumber of TiN nanoparticles are evenly distributed on the surface of the coating.