A method of using three-point bending tests to evaluate hydrogen embrittlement was applied to clarify effects of nickel co-deposition amounts in Zn-Ni alloy electroplating on hydrogen embrittlement of SK85 steel sheets. Hydrogen embrittlement occurred in all plating immediately after plating, irrespective of the nickel co-deposition amount. Diffusive hydrogen, which is responsible for hydrogen embrittlement, was detected in each plated specimen before baking at around 200 ℃. That finding is consistent with hydrogen embrittlement results. However, after baking, diffusible hydrogen at nearly 200 ℃, which is responsible for hydrogen embrittlement, was desorbed from all specimens. These results, which demonstrate that zinc plating without detectable diffusible hydrogen exhibits hydrogen embrittlement, support the hydrogen vacancy cluster theory: hydrogen absorbed during plating generates hydrogen vacancy clusters, which form voids and engender fracture.

Fine bubbles（FBs）, bubbles of less than 100 μm diameter, have attracted attention in recent years. These have been applied via new technology in widely diverse fields, not only in industry, but also in agriculture and fisheries, and in our daily lives for medical and cosmetic effects. Their applications continue to expand.

For surface treatment particularly, FBs are attracting much interest for their effectiveness at cleaning, water quality improvement, surface modification, and wastewater treatment. Organic additives such as brighteners and wetting agents can be added to an electroplating solution. Moreover, the properties and functionality of a coating can be maintained when they are added in the proper ratio. In such cases, activated carbon treatment is performed to adjust the organic additives' concentration. However, because activated carbon treatment is time-consuming, it is often performed on holidays when the production line is stopped, which places heavy burdens on workers.

As described herein, we applied FB instead of activated carbon treatment to a copper sulfate plating solution, and thereby confirmed that ozone FB treatment is applicable for decomposing organic additives.

Hydrogen co-deposited in Pd films electrodeposited at a 298 K bath temperature existed as vacancy-hydrogen clusters and molecular hydrogen in nanovoids. At a 278 K bath temperature, the current efficiency of Pd deposition decreased and interstitial hydrogen existed. The hydrogen concentration in Pd films increased concomitantly with increasing film thickness at both bath temperatures.