摘要
Nanocrystalline chromium coating was prepared by pulse electrodeposition from trivalent chromium bath containing carboxylate-urea as complexing agent. The effects of electrodeposition parameters such as current density,bath temperature and solution concentration on the thickness and electrodeposition velocity of Cr deposited films were investigated. The crystallographic structures,morphology and chemical composition of Cr deposited films were analyzed by means of XRD,SEM and EDS. The results indicate that the deposited films with thickness up to 11.2 μm possess a smooth and clean appearance,and the grain size is less than 100 nm. The coating is pure chromium and the Cr deposit has face-centered cubic(fcc) structure and exhibits a(210) growth preference. Both the electrodeposition velocity and thickness exist maximum under different concentration complex agents,ureas,acetates,different temperatures and current densities. Compared with direct current electrodeposition,the thicker coating and finer grains can be obtained at lower temperature and current density by pulse electrodeposition. The electrodepostion velocity is about 0.24 μm/min,which is faster than that by direct current electrodeposition. In 1 mol/L H2SO4,3.5% NaCl and 10% NaOH solution,corrosion potential of Cr pulse-deposited film is about 100 mV higher than that of direct current. Corrosion and passivation current densities are lower and the nanocrystalline exhibits better corrosion resistance.
Nanocrystalline chromium coating was prepared by pulse electrodeposition from trivalent chromium bath containing carboxylate-urea as complexing agent. The effects of electrodeposition parameters such as current density, bath temperature and solution concentration on the thickness and electrodeposition velocity of Cr deposited films were investigated. The crystallographic structures, morphology and chemical composition of Cr deposited films were analyzed by means of XRD, SEM and EDS. The results indicate that the deposited films with thickness up to 11.2 μm possess a smooth and clean appearance, and the grain size is less than 100 nm. The coating is pure chromium and the Cr deposit has face-centered cubic （fcc） structure and exhibits a （210） growth preference. Both the electrodeposition velocity and thickness exist maximum under different concentration complex agents, ureas, acetates, different temperatures and current densities. Compared with direct current electrodeposition, the thicker coating and finer grains can be obtained at lower temperature and current density by pulse electrodeposition. The electrodepostion velocity is about 0.24 μm/min, which is faster than that by direct current electrodeposition. In l mol/L H2SO4, 3.5% NaCl and 10% NaOH solution, corrosion potential of Cr pulse-deposited film is about 100 mV higher than that of direct current. Corrosion and passivation current densities are lower and the nanocrystalline exhibits better corrosion resistance.
出处
《中国有色金属学会会刊：英文版》
CSCD
2007年第A02期685-691,共7页
Transactions of Nonferrous Metals Society of China
基金
Project(06JJ30021) supported by the Natural Science Foundation of Hunan Province, China
Project(06C259) supported by the Science Foundation of Education Department of Hunan Province, China
关键词
纳米晶
脉冲电沉积
三价铬
铬涂层
pulse electrodeposition
trivalent chromium
chromium coating
nanocrystalline
