Bath nickel/zinc

Examples of plating solutions having good throwing power include cyanide plating baths such as copper, zinc, cadmium, silver, and gold, and noncyanide alkaline zinc baths. Examples of poorer throwing power baths are acid baths such as copper, nickel, zinc, and hexavalent chromium. 

Aramaki et al. [60] confirmed that ultrasonic waves modified cathodic polarization, so that a higher plating rate could be achieved for gold. Walker et al. [52] have found similar results for zinc plated out from a sodium zincate bath. The zinc plated out at a much faster rate in the presence of ultrasound (i.e. 1950 A m 2), when compared to the rate measured using a silent bath (250 A m-2). Similar effects have also been reported for many other metals including chromium [61] and silver [62] for nickel a 5- to 10-fold rate increase was observed [63]. 

Organic wastes include fecal material from humans and animals, either from municipal sewre e systems or concentrated livestock agriculture. Most water naturally has some minerals dissolved in it, which vary by locality. When higher concentrations of iron, copper, chromium, platinum, mercury, nickel, zinc, and tin are discharged into waterways because of mining or industrial operations, the concentration can be toxic to aquatic life and cause metabolic diseases or cancer in humans who drink or bathe in the... 

Large concentration differences between the individual anions are observed in nickel/zinc plating baths, in which both metals are introduced as sulfates with a total concentration of 130 g/L. In order to determine traces of other anions such... 

Figure 10.158 Separation of fluoride, chloride, and nitrate in a nickel/zinc plating bath. Separator column Metrosep Anion Dual 2 eluent ...

Fig. 12.4 Corrosion diagram for a zinc diecasting in a nickel plating bath, pH 2-2. There are two possible cathodic reactions, hydrogen evolution (H) and nickel ion reduction (AO. The corrosion current is the sum of the partial cathode currents. Even with live entry the potential is still too high to suppress corrosion, though the rate is reduced to...

A more dilute strike bath is employed for obtaining the initial deposit on steel, while for strongly recessed parts, e.g. tubular work, an immersion nickel deposit has been used. A short cyanide copper strike is used before plating on zinc-base die castings. 

A further development is the use of a combined chromium-nickel-chromium or nickel-chromium-nickel-chromium deposit on steel- or zinc-base alloy articlesAn advantage of this system is that the first chromium layer need not be plated within the bright range of the chromium bath, so that plating can be carried out under conditions giving deposits of maximum corrosion resistance such conditions do not coincide with those under which fully bright chromium plate is obtained. 

Hohnadel, D. C., Sunderman, F. W., Jr., Nechay, M. W., and McNeely, M. D. "Atomic Absorption Spectrometry of Nickel, Copper, Zinc, and Lead In Sweat from Healthy Subjects during Sauna Bathing". Clin. Chem. (1973), 19, 1288-1292. 

Pickling done before coating may use a mildly acidic bath such spent liquor is not considered hazardous. Waste pickle liquor flows typically range between 10 and 20 gal/t of pickled product. Rinsewater flows may range from less than 70 gal/t for bar products to more than 1000 gal/t for certain flat-rolled products. The principal pollutants in rinsewater include TSS, dissolved iron, and metals. For carbon steel operations, the principal metals are lead and zinc for specialty and stainless steels the metals include chromium and nickel.15... 

The design and capacity of an RO unit is dependent upon the type of chemicals in the plating solution and the dragout solution rate. Certain chemicals require specific membranes. For instance, polyamide membranes work best on zinc chloride and nickel baths, and polyether/amide membranes are suggested for chromic acid and acid copper solutions. The flow rate across the membrane is very important. It should be set at a rate to obtain maximum product recovery. RO systems have a 95% recovery rate with some materials and with optimum membrane selection.22... 

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