Corrosion of Tin Plate

Atmospheric attack of tin plate in humid atmospheres results in the corrosion and production of rust. This occurs in neutral or near-neutral conditions. The presence of contaminants, which change the pH, might result in the opposite process, namely detinning. 

Aqueous external corrosion results in rusting, pitting and ultimately perforation. Under certain conditions detinning may also occur. Perforation is of very serious concern because of loss of product, along with the more serious problem of contamination due to ingress of foreign material such as microbes in food cans. 

The corroding agents in the cans are totally different and depend upon the material in the cans. The materials inside the cans can be foods, beverages, domestic cleaners, paints, industrial products, pharmaceuticals, aerosols and a host of others. This being the case the products in the can present many corrosion scenarios. 

For the formation of tin complexes it is necessary to have stannous ions in solution, and for this to happen the electrons released by the oxidation of tin may be consumed by hydrogen evolution at the iron centers in the pores of the tin plate. As tin dissolves more of the steel surface is available for the hydrogen evolution reaction and 

Some of the factors that contribute to the internal corrosion of tin plate cans are (i) the ratio and concentrations of citric to malic acids which in turn depend upon the strain of fruit, the extent of ripeness (ii) nitrate present in the fertilizers may find its way into fruits and vegetables and the nitrate may be reduced to hydroxylamine and support the detinning process (iii) pesticides containing dithiocarbomates may find their way in and attack iron (iv) phosphates, citrates and the low pH of cola-type beverage may dissolve iron (iv) meats, fish and peas contain sulfur-bonded protein molecules, which can decompose to H2S and attack the tin and iron, forming the respective sulfides. Hydrogen sulfide can react with Sn and Fe, yielding FeS and SnS, which are not poisonous, but impart some color to the canned product. 

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A problem discovered by an air force corrosion engineer was the corrosion of tin-plated electrical connector pins mated with gold-plated sockets. Fretting corrosion between these very small contacts appears to have been implicated in as many as six F-16 fighter aircraft crashes when their main fuel shutoff valves closed uncommanded (17). 

We noted that a tin-plated steel can corrodes more quickly than an unplated steel can. In cases of galvanic corrosion, one cannot expect standard conditions. Suppose that you want to study the galvanic corrosion of tin-plated steel by constructing a cell... 

Gruenwedel, D.W. and Patnaik, R.K. (1973). Model studies regarding the internal corrosion of tin-plated food cans. IV. Polarographic investigation of the interaction of Tin (II) -ions with L-cysteine. Chem. Mikrobiol. Technol. Lebensra.. 2, 97-101. 

Toste AP, Polach KJ, White TW (1994) Degradation of citric acid in a simulated, mixed nuclear waste radiolytic versus chemical forces. Waste Manage 14 27-34 Gire G (1931) Corrosion of tin plates used in the manufacture of containers for canned food. Ann Ealsif Eraudes 24 355-362... 

Tin coatings are widely used in the electrical industry because of their good contact properties and in the food industry because of low toxicity. In addition to pure tin coatings a number of alloy coatings have been developed for special applications, e.g. tin-lead (terne plate), tin-zinc, tin-cadmium, tin-bronze and tin-nickel. Reference should be made to Section 13.5 and to the publication by Britton for data on the corrosion of tin and its alloys. 

One of the most important direct uses for nitromethane is in the stabilization of halo-genated hydrocarbons. For example, small amounts of nitromethane are widely used in industry to form stable non-corrosive mixtures with 1,1,1-trichloroethane for vapour degreasing, dry cleaning and for cleaning semiconductors and lenses. It is also used to stabilize the halogenated propellants for aerosols and to inhibit corrosion on the interiors of tin-plated steel cans containing water-based aerosol formulations (Markofsky, 1991 Angus Chemical Co., 1998). 

Tinplate. Immersion of pickled iron or steel in molten tin results in the material known as tinplate, from which cans, caps, pails, pans, and so forth are made. The objective of tin-plating is to obtain a very thin coating of tin that is free from cracks, holes, or other imperfections. The reason for this latter requirement becomes clear if one considers the nature of the galvanic battery cell involving the metals iron and tin. Since iron is more active than tin, an imperfection in a coating of tin results in preferential corrosion of iron hence, an imperfect tin plating,... 

Cl 77860 Cl Pigment metal 5 EINECS 231-141-8 HSDB 5035 Metallic tin Silver matt powder Tin Tin, elemental Tin flake Tin, inorganic compounds (except oxides) Tin, metal Tin powder Wang Zinn. Element Used In manufacture of tin plate, anodes, corrosion-resistant coatings, manufacture of chemicals, mp = 232° bp= 2507° d 7.31. Atomergic Chemetals Cerac M T Harshaw Noah Cham. ... 

Our observation about the relative corrosivities of various plated steels suggests that we need to express the cell potential numerically. Just how strongly is steel driven toward corrosion when connected to tin Can the tendency of a metal such as zinc to protect steel be of practical use For answers to these questions, we return to the concept of cell potential. 

Electroplating is commonly used to prevent corrosion (rusting) of metal. Zinc metal electroplated onto steel prevents rust The corrosion of tin cans is inhibited by a very thin layer of tin plated onto rolled steel. 

R. R. Habtwbll, Certain Aspects of Internal Corrosion in Tin Plate Containers.. 327... 

Turning to another area, mention will be made of the use of tin cans for various preserved foods. The tin may not always be made of tin plate there are other metals and alloys currently in use. In a recent publication from the Applied Research Laboratory of the U. S. Steel Corporation, R. P. Fran-kenthal( ) has described some most interesting results regarding corrosion of these materials. It must be remembered that cold-working exerts a considerable influence on the susceptibility of a metal to corrosion such effects have been known for quite a time. A great number of results from investigations into the role of deformation and surface treatment have been published in late years. 

Park Y. W., Sankara Narayanan T. S. N. and Lee K. Y. (2006a), Effect of fretting amplitude and frequency on the fretting corrosion behaviour of tin plated contacts . Surf. Coat. TechnoL, 201,2181-92. (doi 10.1016/j.surfcoat.2006.03.031)... 

It is particularly important that all types of fuel samples, which pass a low-tarnish strip classification, be collected in clean, dark glass bottles, plastic bottles, or other suitable containers that will not affect the corrosive properties of the fuel, Avoid the use of tin plate containers for collection of samples, since experience has shown that they may contribute to the corrosiveness of the sample. 

Fretting corrosion (36,37) can lead to high contact resistance of base metal contacts, such as tin plate in electronic connectors. Small cycHcal displacements of the connector halves occur because of external vibration or differential thermal expansion and contraction of the mating contacts. The wear debris that is formed remains in the contact zone. The accumulation of oxide debris in the contact region leads to increased contact resistance. Solutions to this problem are stmctures that do not permit movement of contact surfaces with respect to one another, the use of gold as a contact finish, and the appHcation of thick coatings of contact lubricants and greases, which reduce the rate of wear and restrict access of air to the contact surfaces. 

Tin—Nickel. AHoy deposits having 65% fin have been commercially plated siace about 1951 (135). The 65% fin alloy exhibits good resistance to chemical attack, staining, and atmospheric corrosion, especially when plated copper or bron2e undercoats are used. This alloy has a low coefficient of friction. Deposits are solderable, hard (650—710 HV ), act as etch resists, and find use ia pfinted circuit boards, watch parts, and as a substitute for chromium ia some apphcafions. The rose-pink color of 65% fin is attractive. In marine exposure, tin—nickel is about equal to nickel—chromium deposits, but has been found to be superior ia some iadustfial exposure sites. Chromium topcoats iacrease the protection further. Tia-nickel deposits are bfitde and difficult to strip from steel. Temperature of deposits should be kept below 300°C. 

Tin will protect copper from corrosion by neutral water. Pure tin is anodic to copper, and protects discontinuities by sacrificial corrosion. Both intermetallic phases are strongly cathodic to copper, and corrosion is stimulated at gaps in wholly alloyed coatings. An adequate thickness of tin is needed for long service, e.g. 25-50 xm. Another diffusion problem occurs with tin-plated brass. Zinc passes very quickly to the tin surface, where under conditions of damp storage zinc corrosion products produce a film... 

The importance of tin, as Dr. F. J. North of the National Museum of Wales pointed out, cannot be correctly judged from the quantities used. Since the days of ancient Rome, it has been applied as an extremely thin protective layer, or tin plate, to other metals to make them more resistant to corrosion and safer as receptacles for foods (224). In 1941 the National Museum of Wales held a special exhibition entitled Tin through the Ages in Arts, Crafts, and Industry. ... 

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