Effect of Saccharose Concentration and Temperature on the Internal Stress and Corrosion Resistance of Electroplated Chromium Coatings Prepared from Chromium (III) Bath

摘要

The trivalent chromium carbon coatings are electroplated from different electroplating temperature (10,0 and -5℃) and different concentration (0.01, 0.02 and 0.03 M) of saccharose (C 12 H 22 O 11 ). Thesaccharose play a role of stress inhibitor in the bath during electroplating process. The results of internalstress analysis show that the internal stress of the trivalent chromium carbon coating decreases with theincrease of concentration of saccharose at individual electroplating temperatures, this shows thatsaccharose has the effect on suppressing the accumulation of stress within the coating. Moreover, theelectroplating temperature also affect the internal stress of trivalent chromium carbon coatings i.e. thelower electroplating temperature (-5℃) will reduce the accumulation of stress within the coating duringelectroplating. The smallest internal stress of trivalent chromium carbon coatings is 13.4 MPa,electroplated at -5℃ with a concentration of saccharose at 0.02 M. The best i corr is approximately at1.32×10 -6 A/dm 2 , this coatings is also electroplated at -5℃ and the concentration of saccharose at 0.02M. The results indicated that both electroplating temperature and concentration of saccharose can reducethe internal stress within trivalent chromium carbon coatings and decrease the through-deposit crackingwithin coatings, thereby improving the corrosion resistance of coatings.