Electroless nickel-phosphorus coating on boron carbide particles

Abstract

The present work aimed at studying electroless coating of nickel-phosphorus (Ni-P) onto boron carbide (B4C) particles with average particle sizes of 93 and 32 mu m. Prior to the coating process, B4C particle surfaces were sensitized using SnCl2 and HCl solution and activated in PdCl2 and HCl solutions. In the electroless coating bath, nickel sulphate (NiSO4 center dot 6H(2)O), sodium hypophosphite (NaH2PO2 center dot H2O) and sodium citrate (Na3C5H5O7.5, 5H(2)O) were used as Ni2+ source, reducing agent and complexing agent, respectively. The morphology and the chemical composition of the coating layers were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Characterization results showed that B4C particle surfaces were successfully coated by a homogeneous and continuous Ni-P layer. (C) 2012 Elsevier B.V. All rights reserved.