화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.159, No.6, D393-D399, 2012
The Relationship between Nano Crystallite Structure and Internal Stress in Ni Coatings Electrodeposited by Watts Bath Electrolyte Mixed with Supercritical CO2
In this study, the internal stress of Ni coating electroplated in the supercritical-CO2 (Sc-CO2) mixed Watts bath was investigated with a focus on the effects of plating parameters and additives. Both the internal stresses of the Ni coatings and their corresponding microstructures were examined. A relationship is found that the internal stress of the Ni coating was inversely proportional to its grain size and the Ni{200}/Ni{111} peak fraction in the measured X-ray diffraction pattern. The smaller grain size, accompanied with higher Ni{111} intensity, resulted in the higher internal stress of the coating, and vice versa. A proposed theoretical model, which took both the grain size and preferred crystalline orientation into account, correlated closely with experimental results in the internal stress. As a result, the presence of surfactant in the Sc-CO2 electrolyte increased the internal stress of Ni coating. However, a reduction of internal stress is made possible by varying four factors: the raising of current density, the increasing of plating temperature, the lowering of plating pressure, and the addition of saccharin into electrolyte. A comparison to the internal stress of Ni coatings plated by the conventional method was also discussed in this study. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.061206jes] All rights reserved.