Plated on Steel

The coating is, in addition, useful in preventing galvanic corrosion . Plated on steel which is to be used in contact with aluminium alloys, it protects the steel and does not stimulate the corrosion of the light alloy and is itself not consumed as rapidly as a 100% zinc coating. 

Ion vapor deposition (IVD) was developed from vacuum deposition by McDonnell Douglas Corporation. They used IVD of aluminum as a substitute for cadmium plating on steel aircraft parts. Aluminum provides corrosion protection similar to cadmium, it can withstand 925°F temperatures as opposed to 450°F for cadmium, and it is cheaper on a volume basis than either cadmium or zinc (Higgins 1989). Aluminum is also far less toxic than cadmium, and its use in an IVD system offers safer working conditions and less environmental risk. 

The hydrogen overvoltage of cadmium is rather large and cadmium may be used, plated on steel, as an alternative to lead. Cadmium has been used as cathode material in the hydrodimerization of acrylonitrile (Chapter 31). Magnesium may be used in reductive dimerization of aliphatic esters [459]. 

Cadmium is used in a number of industrial processes, but for most of its uses there are alternatives of lower toxicity. The principal applications of cadmium fall into five categories protective plating on steel, stabilizers for polyvinyl chloride, pigments in plastics and glasses, electrode material in nickel-cadmium batteries, and as a component of various alloys. 

One of the first important applications of x-rays to the measurement of the thickness of coatings was in the control of tin plate on steel, using attenuation of the Fe Ka line. The incident radiation may be either polychromatic or monochromatic (the latter makes isolation of the signal from background easier). However, it is essential that the primary radiation be of sufficient energy to excite the substrate. In the example of tin on steel, x-rays or y-rays in the 10 to 25 keV range will excite... 

Another example is chromium plating on steel parts. The typical process consists of a primary copper layer, a secondary nickel layer, and the final chromium plating. 

Figure 9 Determination of the thickness of tin plate on steel substrate.

The metals used in sliding contact with the experimental carbon-t3q)e materials included type 304 austenitic stainless steel, electrolytic copper (99,9 J ) Cu), and electrolytic chromium plating on steel. 

A compilation of modified salt fog tests, ASTM G 85, includes five annexes. The first. Acetic Acid Salt Spray (Fog) Testing, was originally published as ASTM B 287. In this annex, the salt solution is prepared in accordance with B 117, then tidjusted to a pH in the 3.1-3.3 range with the acetic acid. The acetic acid salt spray test is used for decorative chromium plating on steel [4]. The test duration is typically 144-240 h. 

The addition of acetic acid to the salt solution used in the salt spray tests was introduced first in 1945 and is currently Annex A1 of ASTM G 85 [Practice for Modified Salt Spray (Fog) Testing]. The acidified test is much more corrosive than the normal salt spray test and is capable of producing a pattern of attack similar to that developed in outdoor service for decorative chromium plate on steel or zinc. It is much slower than the copper-accelerated acetic acid-salt spray (CASS) test in ASTM B 368 [Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)], [77] which resembles it in effect. 

Inside the tin can Sn" "" " forms complex ions with the organic liquids food. This causes reversal of polarity and tin becomes active and corrodes as Sn++. The corrosion of the base metal (carbon steel) is thus prevented by the sacrificial action of tin coating. The tin ions also inhibit the corrosion of base carbon steel by plating on the iron. Tin is plated on steel as Sn-Fe alloy which has a more noble potential than steel. Thus, within the food container the corrosion of steel is prevented. 

Nickel plating on steel by chemical reduction, A. Brenner and G. E. Riddell, J. Res. National Bureau Standards, 1946, 37, 31 Deposition of nickel and cohalt hy chemical reduction, A. Brenner and G. E. RiddeU, J. Res. National Bureau Standards, 1947, 39, 385. 

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