Zinc-nickel coatings

Arsenault, B., Champagne, B., Lambert, P., and Daillaire, S. (1989). Zinc-nickel coatings for improved adherence and corrosion resistance. Thermal Spray Technology New Ideas and Processes. ASM International, Metals Park, OH, pp. 409-416. Ashworth, V., and Fairhurst, D. (1975). The effect of temperature on the behaviour of a zinc-mild steel couple in a solution containing chloride ions. Corros. Sci., 75(11-12), 669-686. 

Zinc-nickel coatings contain 10-14 % nickel and are typically applied by electroplating at coating thicknesses ranging from 3-6 pm. Zinc-nickel coatings are also commonly used by the automotive industry for exposed and unexposed panels because of their superior weldability (over pure zinc coatings) and good formability [76]. 

Joints tend to weaken more rapidly if they are stressed during exposure. Davies and Fay (1993) reported the time to failure for joints, both stressed and unstressed, with mild steel and zinc-coated steel adherends. Results for zinc-nickel coated steels are shown in O Fig- 31.8 showing that all unstressed joints survived for 2.5 years and that survival of the others decreases with increasing stress. 

Average failure times of the zinc-nickel coated steel joints... 

Zinc—Nickel. Steel has the best salt spray resistance when the nickel is 12—13% of the alloy. At increasing nickel contents, the deposit becomes more difficult to chromate and more noble, eventually becoming cathodic to steel. At those levels and above, corrosion resistance usually decreases and is dependent on a complete lack of porosity for protection of the steel. In efforts to replace cadmium and nickel—ca dmium diffused coatings in the aircraft industry, 2inc—nickel has insufficient wear properties for some appHcation, but is under study as an undercoat to various electroless nickel top coats (153). 

Kutznelnigg, Pitting, the Typical Corrosion of Nickel Coatings , Korrosion, 13, 64 (1960) Schmeken, H., Electrochemical Measurements on Corrosion of Zinc with Regard to Pitting Possibilities , Korrosion, 13, 65 (I960)... 

Hall, D. E. Electrodeposited Zinc-Nickel Alloy Coatings —A Review , Plating and Surface Fin., 59-65 (Nov. 1983)... 

Other commonly employed redox electrodes are metals such as copper, cobalt, silver, zinc, nickel, and other transition metals. Some p-block metals such as tin, lead and indium can also function as redox electrodes. However, s-block metals such as magnesium do not make good redox electrodes since the elemental metal is reactive and forms a layer of oxide coating, which leads to poor reproducibility, poor electronic conductivity and electrode potentials that are difficult to interpret, (see Section 3.3.1). 

A similar system, containing the same active materials, is the so-called alkaline battery. This type of battery differs from the Leclanche cell in that the electrolyte is concentrated KOH, the zinc is in the form of a high-surface-area paste and the casing is made of nickel-coated steel. It has a much higher power density, because of the higher conductivity of the electrolyte and the larger surface area of... 

With galvanoaluminum coatings like zinc-nickel alloys, long duration times were reached. Regarding thermal and mechanical stress, the corrosion-protective effect of the zinc-nickel alloy layers is clearly inferior to that of galvanoaluminum. The short life span of IVD-aluminum deposits in comparison to galvanoaluminum is notable. This difference may result from the different microstructures of these two types of aluminum coatings [97, 156]. 

Heavy metal skins Coatings of iron, manganese, copper, zinc, nickel, mercury, lead and other heavy metals on rocks in natural and human-altered settings... 

Typical fillers glass fiber, carbon fiber, aramid, antimony trioxide, zinc borate, stainless steel fiber, graphite, nickel coated graphite, aluminum flakes, metallized glass... 

Typical fillers calcium carbonate, glass fiber, carbon fiber, zinc borate, PTFE, aluminum flake, graphite fiber, nickel coated graphite fiber... 

Impure copper as obtained by the reduction of its ores contains small amount of other metals like iron, zinc, nickel, silver and gold with which the starting copper ores are associated. A slab of this impure copper is made the anode of an electrolytic cell in which a graphite-coated sheet of pure copper constitutes the cathode, and an aqueous solution of copper sulphate containing sulphuric acid is the electrolyte. Electricity is passed through the cell from a source of direct electric... 

---