回転リングディスク電極を用いた界面pH測定とそのNi-Al(OH)₃複合めっきへの適用

抄録

The interfacial pH during Ni plating from the Watts bath was measured by using a rotating ring disk electrode system where the Sb-plated ring electrode acts as a pH sensor. It was clarified that a linear relationship exists between the electrode potential of the Sb-plated ring electrode and the pH in the range from 2.0 to 6.5 and was also clarified that the Sb-plated rotating ring electrode could be used as a pH sensor for the electroplating process in these pH ranges. The Ni-Al(OH)₃ composite film was electrodeposited by controlling current density under certain conditions, while the rise of interfacial pH during the plating process was estimated from the in situ pH measurement described above. The results of the SEM/EDX observations showed that minute particles, probably aluminum hydroxide, could be deposited with nickel from Al³⁺ contained in a non-turbid Watts bath under certain conditions determined by the interfacial pH measurement described herein.