Manufacturing of functionally graded Ni–ZrO₂ composite coating controlled by stirring rate of the electroplating bath

Abstract

For the first time, functionally ZrO₂ content graded Ni–ZrO₂ composite coating has been successfully co-electrodeposited from a bath with gradually increasing stirring rate. For this, different composite coatings were electroplated in the same bath with different stirring rates to find the optimum stirring rate in which the maximum content with uniform distribution of ZrO₂ particles in the coating can be achieved. To produce ZrO₂ content graded Ni–ZrO₂ composite coating, the stirring rate was continuously increased from 0 to optimum value. The results showed that functionally graded Ni–ZrO₂ composite coating has been successfully electroplated with continuous gradient distribution of Zirconia content in the coating using controlling of bath stirring rate. With increasing of ZrO₂ particles content, the microhardness increases from the interface towards the surface of the coating. This could provide a high wear resistance with high adhesion of the coating to the substrate.

Keywords:

• Co-electrodeposition
• Composite coating
• Functionally graded materials
• Microhardness