PROPERTIES OF TIN:
TIN is a soft white metal which can readily be scratch-brushed, polished or flow melted to get a bright finish. TIN has a low melting point 232°C (450°F) & is used as a minor & major constituent in many alloy solders. TIN is non toxic & is not greatly affected by the organic acids in foodstuffs therefore Tin is used for coating “tin cans”. TIN is not readily tarnished by sulphur compounds but is attacked by strong mineral acids. TIN is soluble in hot solutions of caustic soda & potash, and for this reason caustic alkalis are not recommended for the degreasing & cleaning of tinned ware. TIN that is electroplated dull or bright is widely used as a protective coating on ferrous & non-ferrous metals. Electroplated alloys of TIN is used in decorative & industrial applications.
The main application of TIN is for products which will come into contact with foodstuffs & the majority of tinplate is produced by electrolytic processes. Other applications include plating of non-ferrous electrical & electronic components, as a measure of protection against atmospheric corrosion and the tinning of articles as an aid to soft soldering. TIN plating is also used in the nitriding of steels to prevent carburization of selected areas in case-hardening, on brass components as an aid to solderability or for electronic puposes. It is advisable to apply a thin coating of either copper or nickel before Tin plating, a suitable thickness should be 2 to 5 microns. TIN can be used for a few decorative applications, for example the immersion tinning of pins & press studs to have a bright silvery white finish.