Creation of Ni-B/Ni-P electroless coating on the WC particles without surface activator

Abstract

One of the methods for improving metal-ceramic interface and suppression of agglomeration is the formation of a monolayer electroless coating on the particles. Investigations indicated that Ni-B monolayers should be first formed to develop in the next process an electroless Ni-P coating with the morphology of cauliflower. It was possible to produce a Ni-B layer on WC particles when a bath was heated at a temperature of 95 °C by using sodium borohydride and an appropriate stabilizer. Following this process, the Ni-P electroless coating was deposited on WC particles at 85 °C. In this way, two layers of electroless coating of Ni-B/Ni-P on the WC ceramic particles without using the surface activator were produced successfully. The coating morphology and surface analysis were performed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results showed that only the degreasing with acetone as a surface preparation of ceramic particles is sufficient to make a Ni-P or Ni-B coating. Electroless Ni-B coating with appropriate adhesion to the surface produces an acceptable surface for the electroless Ni -P coating formation.