Articles – Tin Alloys
Tin is obtained from a mineral by the name of cassiterite which is tin oxide, SnO2. The most significant producers of tin are Bolivia, China, Indonesia, Thailand, Malaysia and Peru. In 1985 during the price collapse of tin, the Cornish mines were almost completely wiped out. South Crofty is the only mine that has been working in recent years. There are still some idle and completely flooded negotiations continuously going on to restart the mine. Tin alloys are very popular for a number of reasons.
One of the most important characteristics of tin is the ease with which it alloys or mixes with the majority of other metals. It is this quality together with the low melting point which makes it an essential ingredient of most solders. It is not toxic and it does not corrode all that rapidly making it ideal as a protection for steel for food and drinks.
Tin can characteristics are also important in pewter. The very high boiling point allows it to be used as a smooth molten surface to make the ‘float’ glass.
The Tin wedding anniversary celebrates 10 years of marriage, and making tin or pewter the perfect gift for such an occasion. The ‘cry’ of tin is a property that when bent a cracking noise is emitted, some high tin alloys exhibit this property to a lesser extent. We have a pewter composition Carn H1 that gives off a pinging sound as it cools after solidification; this particular alloy contains tin antimony copper and bismuth. Tin alloys of tin, bismuth, lead and cadmium in the right proportions will melt well below the boiling point of water at just 70C. Some tin alloys are:
Pewter: is a part of the tin alloys which has had many compositions through the ages the only common ingredient being a high tin content, pewter exploits the beauty and ease of working of tin with additions of other metals being made mostly to strengthen it.
Bronze. Bronze is regarded as an alloy of tin and copper usually less than 12% tin although it often includes other metals to meet specific requirements. Bronze is the first tin alloy used by man but there is much debate about when and how we first deliberately mixed tin and copper as an alloy. Many early ‘bronzes’ don’t contain much tin. Higher tin bronzes are used to cast bells. Brass does not normally contain tin being an alloy of copper and zinc
Solder. Alloy compositions are numerous but the most important are still the tin lead solders which were used by the Romans. Tin melts at around 232Â°C and lead at about 327Â°C. This composition is known as the eutectic. Solders used in electronics account for a significant proportion of tin consumption. Lead free plumbing solder is often tin with about 0.5% copper although many other compositions have been developed.
Bearing materials. Tin has a low coefficient of friction. This is the first consideration in using it as a bearing material, which also forms part of tin alloys. Tin is structurally a weak metal, and when used in bearing applications it is alloyed with copper and antimony for increased hardness, tensile strength and fatigue resistance.
For more information on Tin Alloys, contact us or call 888-513-7971