Brazing of Stainless Steel Using Electrolytic Ni-P Plating Film and Investigation of Corrosion Behavior

Electrodeposited Ni-11 mass%P alloy plating film was fabricated on the surface of stainless steel SUS304 to conduct brazing of SUS304 plates for a heat exchanger. Brazing of SUS304 plates with electrodeposited Ni-11P layers was carried out using a hydrogen reducing furnace. The microstructure and joint strength of the brazed joint were also investigated. From the result of the microstructural observation of the cross section of the joint, it was found that the brazing filler metal is homogeneously distributed without defects such as voids between the SUS304 plates. The results of electrochemical measurements showed that the P-concentrated phase in the Ni-11P alloy is preferentially dissolved in NaCl aqueous solution.

INVESTIGATION OF SOME PROPERTIES OF ZINC-NICKEL ALLOY PLATING WITH TRIETHANOLAMINE, p-AMINOBENZENESULFONIC ACID, AND GELATINE

Anticorrosion requirements for the metallurgy, automotive, and aeronautical industries have increased in recent years, for which alternative plating chemicals must be developed. This study focuses on obtaining a Zn-Ni alloy plating with higher corrosion resistance and brightness. For this purpose, tetraethylenepentaamine as complexing agent, triethanolamine as the surfactant, and gelatin and [Formula: see text]-aminobenzenesulfonic acid as brightening agents for the plating were selected and their optimal concentrations were determined for applications. The optimal Zn-Ni ratio and plating thickness were analyzed using an X-ray Dal device. Improved plating performance of the Zn-Ni alloys was achieved with a Zn-Ni alloy containing 12–14% Ni.

Study on Zn-Mn Alloy Plating on the Surface of Steel Sheet Prepared in Hydrochloric Acid Bath

Zinc plating using the principle of sacrificial anode is used to prevent steel corrosion. Pure zinc plating has some problems and Zn-Mn alloy plating has been studied as one of the measures to increase the corrosion resistance. Zn-Mn alloy plating can be applied to automotive parts requiring high corrosion resistance despite high plating cost. In this study, Zn-Mn alloy plating was electrodeposited in acidic chloride solution. The effects of electrolytic conditions on the composition of the alloy plating in the chloride bath were investigated. As the current density increased, the Zn content decreased and the Mn content increased. As the temperature of the electrolyte increased, the Zn content decreased and the Mn content increased.