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Properties and applications of engineering materials
Published in Alan Darbyshire, Charles Gibson, Mechanical Engineering, 2023
Alan Darbyshire, Charles Gibson
Tin has a very low tensile strength and melting point. It is very soft and malleable and highly corrosion resistant. It is used as a protection for mild steel sheet which is then known as tinplate. Its other main use is as a constituent of soft solder.
Causes of failure
Published in William Bolton, R.A. Higgins, Materials for Engineers and Technicians, 2020
Many pure metals have a good resistance to atmospheric corrosion. Unfortunately, these metals are usually expensive, and many of them are mechanically weak. However, a thin coating of one of these metals can often be used to protect mild steel. Pure tin has an excellent resistance to corrosion, not only by the atmosphere and by water, but by very many other liquids and solutions. Hence, tinplate – that is, mild-steel sheet with a thin coating of tin – is widely used in the canning industry. Figure 26.9 illustrates what happens if a tin coating on mild steel becomes scratched.
Lubricant Packaging and Filling
Published in R. David Whitby, Lubricant Blending and Quality Assurance, 2018
Cans of tin-plated steel, both those that are permanently sealed and those with tops that can be lifted and replaced, are also used predominantly for food storage. Tin-plate containers are also used to hold paints and varnishes and tobacco, medical and cosmetic products. While tin plate is durable and highly resistant to chemical and mechanical damage, aluminium is lighter and more malleable, but interacts more readily with chemical agents. Aluminium is used for beverage cans and provides bottle caps and easy-open tops for other cans. Most aerosol (pressurised) containers, which deliver liquid products in the form of a spray, are based on metal cans.
Surface characterisation of electroplated tinplate with different coating mass
Published in Surface Engineering, 2018
The coating structure of tinplate typically consists of a sheet of mild steel substrate having controlled levels of copper, phosphorus, and sulphur, deposited with a layer of tin coating. The tin is, nowadays, universally coated by electrodepositing from an acid bath. Bath chemistry has been the object of much study [16], and many recipes exist to produce good coatings. Sheet thickness is commonly in a range of 0.15–0.5 mm, and the tendency is to thinner thickness. The tin coatings are on the order of less than 2.0 μm, though they are more commonly expressed in terms of coating mass. Present values range from about 2 g m−2 to about 11 g m−2 on each surface. After plating, the tin coating undergoes momentary fusion (reflowing treatment) by resistive heating followed by quenching in water. The as-deposited coating is converted to a bright, reflective state, and a layer of a tin–iron (FeSn2) alloy is formed between the tin and the steel substrate. A layer of chromium oxide composed of Cr3+ (Cr2O3 or Cr(OH)3) and free Cr arises on the tin, and this is usually obtained by a ‘passivation’ treatment [17]. This process, using chromic acid or sodium dichromate solutions, sometimes with imposed current, leaves some chromium species in the surface. The object of “passivation” is to control oxidation, suppress sulphide formation in use, and facilitate lacquer coating. A layer of oil, commonly dioctyl sebacate (DOS), is applied to facilitate handling. “Thus, from the cross-sectional profile, we have base steel, alloy, tin, oxide with chromium, and oil of the typical structure of tinplate [18].”