화학공학소재연구정보센터
Electrochimica Acta, Vol.114, 851-858, 2013
Pulse-electrodeposited NiP-SiC composite coatings
This paper describes the effect of modulated bipolar current (pulse reverse plating) on the incorporation of micron and submicron sized SiC particles within an electrodeposited Ni-P alloy matrix (dispersion coating). Based on electrochemical measurements, a pulse plating process has been defined and the effects of pulse parameters (type of current, frequency of current pulses and current density), the electrolyte composition and the size of the silicon carbide on the particles incorporation rate, phosphorus co-deposition rate, surface morphology, structure, micro hardness and wear resistance of the deposits has been investigated. The experimental results show that the phosphorus co-deposition and the particles incorporation rate decrease applying higher current density. The reduction of particle size decreases the co-deposition content of the particles within the coating. Application of pulsed current leads to a more compact composite coating, significantly improving the hardness and the tribological behaviour of the Ni/SiC deposits, mainly at higher frequency of the applied current pulses. DC and bipolar pulses generate unfavourable higher co-deposition rate of phosphorus, hence a loss in hardness has been observed. Tailored shift of the properties and alloy composition during the deposition process can be achieved by change of matrix properties via alternation of the pulse sequences. (C) 2013 Published by Elsevier Ltd.