三價鉻鍍浴電鍍成長行為之研究

Electroplating Growth Behavior in Trivalent Chromium Bath

本研究於三價鉻鍍浴中添加氯化鉻、甲酸、硫酸銨與硼酸等藥劑，利用電化學陰極還原曲線測試不同鍍浴之還原反應，並探討不同配方對三價鉻鍍層的結構組成、表面形貌和耐蝕性進行研究之影響。由陰極還原曲線實驗結果顯示，鍍液隨甲酸、硫酸銨與硼酸等藥劑的加入，不僅可使鉻離子還原反應增加且鍍層披覆性較佳。在完整配方（包含氯化鉻、甲酸、硫酸銨與硼酸等藥劑）之鍍層其碳含量平均可達約23 at.%，且耐蝕性優異（腐蝕電流3.06×10-7 A/cm2）；且三價鉻鍍層中表面成分，其組成為類非晶相結構為主，包含Cr、Cr2O3、與Cr-C之化合物。

In this study, the trivalent chromium baths contain of CrCl3, HCOOH, (NH4)2SO4 and H3BO3. The reduction reactions of different trivalent chromium bath were evaluated by using electrochemical cathodic reduction curve. The chemical composition, microstructure, surface morphology, and corrosion resistance of the Cr-C coatings were also studied. Our results show the cathodic reaction of trivalent chromium baths could be increased by sequentially adding HCOOH, (NH4)2SO4 and H3BO3. When the complete formula of bath was set, the trivalent chromium layer has the average carbon content of approximately 23 at.%, and the best corrosion resistance with a corrosion current density of ~ 3.06×10-7 A/cm2. The Cr-C coatings have a nearly amorphous structure and contain Cr, Cr2O3, and various Cr-C compounds.