A new experimental apparatus of electro-codeposited system for NiC composite coatings
N. Sombatsompop, K. Sukeemith, T. Markpin, N. Tareelap
Journal of the American Ceramic Society
Abstract
A new experimental apparatus for nickel杢ungsten carbide electro-codeposited composite coatings was proposed and the char-acteristics of the coating were evaluated in terms of thickness distribution and uniformity, WC particle incorporation and hardness. This proposed experimental apparatus enabled a rotation of the test specimen around itself (cathode rotating; CR) and around the anode (anode circumference rotating; ACR) simultaneously, where the results were compared with...More those obtained by the conventional electro-codeposition (CECD) technique. The proposed coating system was found to enhance the efciency of electrolyte stirring which improved the properties of the coatings. The deposition mechanism of the Ni朩C composite coatings was also proposed in this work. The experimental results suggested that WC particle incorporation and hardness of the coating were dependent on the mode of coating techniques while the coating thickness 2 distributions were not. The coating thickness distribution in all coating techniques increased at low current density around 4? A/dmand then decreased at higher current density. The CECD technique was more sensitive to current density changes than the CR and ACR techniques. The ACR technique gave the best thickness distribution while the CR technique was recommended when a relatively high thickness of the coating was required. The thickness of the coating by the CR technique increased at low self-rotating velocity and decreased with higher self-rotating velocity while that by the ACR technique was dependent on the speed of the cathode self-rotating. The current density did not affect the particle content and average coating hardness in all techniques used. The ACR technique was recommended when requiring high particle incorporation in the coating and high hardness of the coating.
keywords:Electroplating; Nickel ungsten carbide; Cathode rotation
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