Synthesis and Characterization of Cr-WC Composite Coatings by Electrocodeposition

Abstract

Nano sized tungsten Carbide (WC) dispersed chromium composite coatings have been prepared by direct current (DC) and pulse electrodeposition (PED) technique with various pulse frequencies at constant duty cycle, current density on copper substrate from Chromic acid (퐶푟푂3)andsulfuric acid (퐻2푆푂4)solution to enhance the surface mechanical property of traditionalc hromium coating.Zeta Potential test was done on WC dispersed
deionized water solution to know the isoelectric point.To avoid agglomeration of nano particles in plating bathand to get uniform coating, magnetic stirring wa provided during codeposition with prior ultrasonic agitation.Composite coatings with different concentrations of WC were prepared and plane chromium coating was also prepared for comparison. Characterization of WC powder as well as phases, morphology,roughness, micro-hardness,wear of the coatings was studied by the use of XRD,SEM,Stylus Profilometer, micro-hardness tester and ball-on-plate type wear tester.WC dispersion in the coatings was uniform and the average size of dispersed particle of WC was 60 nm. Mechanical characterizations were investigated and greater hardness and wear resistance incomposite coatings deposited by pulsed DC compared to composite coatings deposited at DC condition. Mechanical properties were intensified in terms of hardness and wear resistance by the incorpor ation of WC in the composite coating.