Effect of current density on microstructure and performance of Ni-TiN coatings

Ni-TiN coatings were prepared on 45 steel by pulse electrodepositing method. The effect of current density on the content of TiN particle,morphology and microhardness of Ni-TiNcoatings were studied by atomic absorption spectrophotometer(AAS),scanning electron microscope(SEM)and microhardness tester. The results show that TiN particles content in the coating firstly increases and then decreases with the increase of current density. When the current density is 7 A/dm2,the TiN content reaches 9.89%. As for the current density of 5~7 A/dm2,the surface particle is gradually becoming finer with the increase of current density. The microhardness of the coatings firstly increases and then decreases with the increase of current density,and when the current density is 7 A/dm2,the microhardness reaches 844.5HV.