This study examined the influence of degradation of additive agents upon copper sulfate plating, i.e. polyethylene glycol (PEG) as a depressant, Janes green B (JGB) as a leveler, and bis(3-sulfopropyl) disulfide disodium salt (SPS) as a brightener. Trace analysis was conducted in a copper sulfate bath using high performance liquid chromatography (HPLC), which clarified the respective quantitative limits for measurement of PEG, JGB, and SPS as 10 mg/L, 0.01 mg/L, and 0.15 mg/L. The PEG molecule size and the SPS concentration decreased during electroplating. The value of throwing power was particularly lowered by the PEG degradation. Hydrogenation into N,N-dimethyl-p-phenylenediamine and methylene violet decomposed the JGB, thereby lowering the value of throwing power.

View full abstract

This study investigated the formation of carbon films on a stainless steel surface using cathodic reduction of CO₃^2－ ions in a molten chloride. Various electrolysis methods such as potentiostatic, galvanostatic, galvanostatic pulse, and galvanostatic periodically reversed (PR) electrolysis were used with the aim of obtaining smooth and adhesive films. Potentiostatic and galvanostatic PR electrolysis yielded smooth, dense, and adhesive carbon films, but the electrodeposited carbon films created by potentiostatic electrolysis often peeled away from the substrate when the supplied electricity was increased, possibly because of selective particle growth on the initially deposited, randomly dispersed carbon nucleation sites. However, galvanostatic PR electrolysis produced smooth and adhesive carbon films for which the thickness increased almost linearly along with the supplied electricity. These results suggest that galvanostatic PR electrolysis is the most effective electrolysis method for obtaining smooth, dense, and adhesive carbon films.

View full abstract