Wood's metal 867078 224590232 2008-07-09T15:34:38Z Mikeblas 327592 micrometer link fix '''Wood's metal''', named for American metallurgist [[B. Wood]], is also known as '''Lipowitz's alloy''' or by the commercial names '''cerrobend''', '''bendalloy''' or '''pewtalloy'''. It is a [[fusible alloy]] that [[melting point|becomes liquid]] at approximately 70&nbsp;[[Celsius|°C]] (158&nbsp;[[Fahrenheit|°F]]). It is a [[eutectic]] alloy of 50%&nbsp;[[bismuth]], 26.7%&nbsp;[[lead]], 13.3%&nbsp;[[tin]], and 10%&nbsp;[[cadmium]] by weight.<ref name="CSTN" > {{cite web | title = "Gardner's Chemical Synonyms and Trade Names" | publisher = [[John Wiley & Sons]] | url = http://www.wiley.com/WileyCDA/WileyTitle/productCd-0566081903.html }} </ref> == Applications == Wood's metal is useful as a low-melting [[solder]], low-temperature [[casting]] metal, high temperature coupling fluid in [[heat bath]]s, and as a fire-melted valve element in [[fire sprinkler]] systems in buildings. Medical [[gas cylinders]] in the [[United Kingdom]] have a Wood's metal seal which melts in fire, allowing the gas to escape and reducing the risk of [[gas explosion]]. A common use is as a filler when bending thin-walled metal [[tubing|tubes]]. For this use the tubing is filled with molten Wood's metal. After the filler solidifies the tubing is bent, and the filler prevents collapse of the tubing. The Wood's metal is then removed by heating, often by boiling in water. Other uses include making custom-shaped apertures and blocks (for example, electron-beam cutouts and lung blocks) for medical radiation treatment, and making metal [[inlay]]s in wood. Wood's metal is also useful for repairing antiques. For example, a bent piece of [[sheet metal]] may be repaired by casting a Wood's metal [[Die (manufacturing)|die]] from a good example. The low melting temperature of Wood's metal makes it unlikely this will harm the original. The damaged piece can then be clamped in the die and slowly tightened to form it back into shape. == Toxicity == Because it contains lead and cadmium contact with the bare skin is thought to be harmful, especially in the molten state. Vapour from cadmium-containing alloys is also known to pose a danger to humans. [[Cadmium poisoning]] carries the risk of respiratory, liver, kidney, and bone damage, loss of smell, and cancer. [[Field's metal]] is its non-toxic alternative. == Related alloys == <!-- Cerrosafe and Cerrolow redirect to this section --> A similar alloy is called '''cerrosafe'''. This non-eutectic alloy melts at 165&nbsp;°F (74&nbsp;°C). It is mainly used by [[gunsmith]]s for making a reference casting of the chamber of a [[firearm]]. When it solidifies it first shrinks, allowing easy removal from the chamber. When it cools it expands back to the exact size of the chamber. The casting can then be directly measured with [[calipers]] or a [[micrometer]] to determine the dimension of the weapon's chamber, which is important for safety. The eutectic alloys '''cerrolow'''&nbsp;'''136''' and '''cerrolow&nbsp;117''' have even lower melting temperatures of 136&nbsp;°F (58&nbsp;°C) and 117&nbsp;°F (47&nbsp;°C) respectively. Their compositions are as follows: {| border="1" ! Alloy !! Melting point !! Eutectic? !! Tin !! Bismuth !! Lead !! Cadmium !! Indium |- |Wood's metal || 70 °C (158 °F) || yes|| 13.3% || 50% || 26.7% || 10% || – |- |Cerrosafe || 74 °C (165°F) || no || 11.3% || 49% || 37.7% || 8.5% || – |- |Cerrolow 136 || 58 °C (136°F) || yes || 12% || 49% || 18% || – || 21% |- |Cerrolow 117 || 47 °C (117°F) || yes || 8.3% || 44.7% || 22.6% || 5.3% || 19.1% |} Other low-melting solders and fusible alloys include [[Field's metal]], [[Rose metal]], [[Galinstan]], [[NaK]], and alloys of [[indium]] and [[bismuth]]. == References == {{reflist}} * ''Birchon's Dictionary of Metallurgy'', London, 1965 * ''Experimental techniques in low-temperature physics'', G. K. White, Oxford University Press, Third Edition {{nofootnotes}} == External links == * Making your own low-melting point eutectic: ''[http://scitoys.com/scitoys/scitoys/thermo/thermo4.html Science Toys: A metal that melts in hot water]'' [[Category:Fusible alloys]] [[Category:Lead alloys]] [[af:Woods-metaal]] [[cs:Woodův kov]] [[da:Woods metal]] [[de:Woodsches Metall]] [[nl:Woodsmetaal]] [[ja:ウッドメタル]] [[pl:Stop Wooda]] [[ru:Сплав Вуда]] [[fi:Woodin metalli]] [[sv:Woods metall]]