In this study, the fabrication of nickel (Ni)-cellulose nanofiber (CNF) composite electroplating films was attempted using sodium carboxymethyl cellulose (CMC) and 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-oxidized CNF as CNF introduced with carboxy groups. As a result, co-deposition was confirmed for both CNFs, and the former showed 82% improvement in surface Vickers hardness compared to the plated film deposited from a conventional Watts bath without CNF. Although the latter showed slightly inferior 71% improvement, the surface roughness measurement showed a smoother surface than that of the plated copper material C1100. On the other hand, the film with CMC had a rough surface. The image analysis showed that the distance between co-deposited CNF on the surface of the plated film was 40% shorter on the specimen with TEMPO CNF than CMC, indicating that a fine dispersion was obtained. In addition, a co-deposition model was proposed in which Ni is deposited from the chelate complex formed between the carboxylate of CNF and Ni ions. CNF is fixed to the plated film surface by Ni deposition and the simultaneous bond of hydrogen ions to the carboxylate, resulting in a return to the carboxy group.

The purpose of this study is to investigate the conditions of fabrication of cellulose nano-fiber (CNF) composited Ni plating film by electroplating method and clarifying the codeposition mechanism. The electroplating was carried out on SUS304H using Watts bath with CNF suspended. The obtained films were evaluated by surface and cross-sectional observation including elemental mapping analysis, X-ray fluorescence analysis and Vickers hardness testing. The obtained film had a double layer structure parallel to the plating surface, and the layer on the substrate side contained a large amount of CNF. This layer is considered to be formed by physical trapping of CNF in the pitting corrosion and the delaminated area inside the substrate caused by the effect of chloride ion and hydrogen gas. It was also suggested that the electrostatic repulsion between CNF and the substrate was one of the factors that resulted in little CNF codeposition within the surface side layer. In addition, the Vickers hardness of the surface was improved by approximately 30% compared to electroplated Ni film without CNF.

A Ni-P plated layer of 20 μm thickness containing 11 wt.% P was formed on the surface of a stainless steel (SUS304) plate by electroplating. The microstructure and joint strength of the brazed joint with the electroplated Ni-11P layer were investigated. The results indicated that the filler metal was homogeneously distributed between the SUS304 plates and no voids or flaws formed in the brazed filler zone. Fe-Ni-Cr solid solutions were formed at the brazed interface. Moreover, P was mainly concentrated in such brazed filler zone to form P-containing phases. The average shear strength of the brazed joints was determined to be 47.3 MPa. The results demonstrated that the brazing of SUS304 plates using the electroplated Ni-11P layer as the filler metal was successfully realized.