Nickel alloys pyrophosphate

Copper-tin deposits can be plated from cyanide or pyrophosphate -baths and deposits are of good corrosion resistance (approximately equivalent to the same thickness of nickel). Hardness values of up to 314 Hy are obtainable for the copper-rich alloys , and up to 530 Hy for the tin-rich alloys can be obtained. (See also Section 13.5.)... 

The most common plating bath uses fluoride to complex the tin. A typical solution contains 45 g/L stannous chloride, 300 g/L nickel chloride hexahydrate, and 55 g/L ammonium bifluoride. It is operated at pH 2.0—2.5 using ammonium hydroxide temperature is 65—75°C and current about 200 A/m2. The bath has excellent throwing power. Air agitation is avoided. The deposit is bright without additives. Anodes are cast nickel, and the tin is replenished by additions of stannous chloride. Alloy anodes of 72% tin have been used to a much lesser extent. Tin—nickel deposits are covered by ASTM (136) and ISO (137) specifications. One other bath based on pyrophosphate has appeared in the literature, but does not seem to be in commercial use. 

Chromel is an alloy composed of nickel, iron, and chromium. A 0.6472-g sample was dissolved and diluted to 250.0 mL. When a 50.00-mL aliquot of 0.05182 M EDTA was mixed with an equal volume of the diluted sample, all three ions were chelated, and a 5.11-mL back-titration with 0.06241 M copper(II) was required. The chromium in a second 50.0-mL aliquot was masked through the addition of hexamethylenetetramine titration of the Fe and Ni required 36.28 mL of 0.05182 M EDTA. Iron and chromium were masked with pyrophosphate in a third 50.0-mL aliquot, and the nickel was titrated with 25.91 mL of the EDTA solution. Calculate the percentages of nickel, chromium, and iron in the alloy. 

Zinc-nickel Zn-Ni alloys with 5 to 15 wt% Ni offer excellent corrosion resistance and are mainly used in the automotive, aerospace, and electronics industries. Above 15% Ni, the alloy coating becomes more noble than steel, and the corrosion-protection mechanism changes from a sacrificial to a pure physical one (comparable to pure Ni coatings, see Sect. 5.5.4.2.2). They can be electrode-posited from acid or alkaline baths. The acid baths are usually based on sulfate, chloride, sulfate-chloride, pyrophosphate, or acetate (Table 15). The system shows anomalous codeposition (see Sect. 5.5.1.2), which has been explained by a hydroxide suppression mechanism [47]. As in the case of Ni-Fe, the alkaline baths must contain complexing agents (see Sect. 5.5.4.6.2). The alloys electroplated from add haths contain approximately 10 to 14% Ni, whereas the alkaline Zn-Ni... 

Yoshiaki Miura has published [1] a procedure for the determination of iron and copper in aluminum alloys, using ethylenediamine tartrate (EDT) and potassium pyrophosphate as base electrolyte. As a result of this investigation, polarographic procedures using ethylenediamine tartrate complexes have been developed for the determination of iron (ferrous), nickel, cadmium, and copper, as well as for mixtures of the latter three elements. 

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