Alloy properties — Tin and tin alloys

Tin (stannum; symbol: Sn) was already known in antiquity, as an alloy with copper, in the so-called Bronze Age. The Phoenicians also knew it in its pure state more than ten centuries before our era. Around 300 B.C., Theophrastus mentions its use as a protective layer for iron against corrosion, and 100 years earlier, Herodotus recounts the existence of the Cassiterides Islands – currently Scilly Islands – at the tip of Cornwall, where the ore was mined. The Chinese, who have also exploited stanniferous deposits since time immemorial, were also familiar with the process of reducing ore with charcoal.

This relatively rare and expensive metal is malleable and ductile; it is harder but less heavy than lead, and its silvery sheen persists for a long time when exposed to dry air, both indoors and out. A characteristic sound made by solidified metal in the form of a stick, which is heard whenever it is bent, is due to the crystals rubbing against each other and is called the cry of tin.

In modern times, tin's many applications are divided between the various fields where its presence is indispensable, either as a constituent of alloys for specific uses (bronzes, solders, regules, etc.), or as a coating for other metals, or in the form of chemical compounds (see the article on Metallurgy and tin recycling [M 2 314] in this treatise). However, tin is almost never used in its pure state, except at an intermediate stage such as, for example, for dipping parts in a molten bath, or for casting anodes for subsequent electroplating, including on steel to obtain tinplate (article on Steels for packaging [M 7 960] , in this treatise).

Refined tin ingots put on the market feed a whole range of industries, most of whose finished products do not even hint at the presence of tin, whether in the steel industry (flat steel products or pearlitic iron castings), mechanical engineering (bearings, sintered parts, tooling, pumps), the automotive industry (radiators, tanks, seats, bearings, engine blocks), electronics (printed circuits, connections), glassmaking (float glass, bottles), ceramics (tiles), organic chemistry (reagents, catalysts, PVC), agrochemicals (fungicides, insecticides, pesticides), electrical...