Wood's metal

Wood's metal

Wood's metal, also known as Lipowitz's alloy or by the commercial names Cerrobend, Bendalloy, Pewtalloy and MCP 158, is a metal alloy that is useful for soldering and making custom metal parts, but its fumes are toxic, as well as being toxic on skin exposure. The alloy is named for Barnabas Wood, who invented and patented the alloy in 1860.[1][2] It is a eutectic, fusible alloy of 50% bismuth, 26.7% lead, 13.3% tin, and 10% cadmium by mass. It has a melting point of approximately 70 °C (158 °F).[3][4]

Applications

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Wood's metal

Uses include making custom-shaped apertures and blocks (for example, electron-beam cutouts and lung blocks) for medical radiation treatment, and making casts of keys that are hard to otherwise duplicate.[5][6]

Like other fusible alloys, e.g. Rose's metal, Wood's metal can be used as a heat-transfer medium in hot baths. Hot baths with Rose's and Wood's metals are not used routinely but are employed at temperatures above 220 °C (428 °F).[7]

At room temperature, Wood's metal has a modulus of elasticity of 12.7 GPa and a yield strength of 26.2 MPa.[8]

Toxicity

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Wood's metal is toxic because it contains lead and cadmium, and contamination of bare skin is considered harmful. Vapour from cadmium-containing alloys is also known to pose a danger to humans.[9] Cadmium poisoning carries the risk of cancer, anosmia (loss of sense of smell), and damage to the liver, kidneys, nerves, bones, and respiratory system. Field's metal is a non-toxic alternative.

The dust may form flammable mixtures with air.[9]

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Alloy Melting point Eutectic? Bismuth
%		 Lead
%		 Tin
%		 Indium
%		 Cadmium
%		 Thallium
%		 Gallium
%		 Antimony
%
Rose's metal 98 °C (208 °F) no 50 25 25 – – – – –
Cerrosafe 74 °C (165 °F) no 42.5 37.7 11.3 – 8.5 – – –
Wood's metal 70 °C (158 °F) yes 50 26.7 13.3 – 10 – – –
Field's metal 62 °C (144 °F) yes 32.5 – 16.5 51 – – – –
Cerrolow 136 58 °C (136 °F) yes 49 18 12 21 – – – –
Cerrolow 117 47.2 °C (117 °F) yes 44.7 22.6 8.3 19.1 5.3 – – –
Bi-Pb-Sn-Cd-In-Tl 41.5 °C (107 °F) yes 40.3 22.2 10.7 17.7 8.1 1.1 – –
Gallium 30.0 °C (86 °F) Pure metal - - - - - - 100 –
Galinstan −19 °C (−2 °F) no <1.5 – 9.5–10.5 21–22 – – 68–69 <1.5

References

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  1. ^ Jensen, William B. (2010). "The Origin of the Name "Onion's Fusible Alloy"" (PDF). Journal of Chemical Education. 87 (10): 1050–1051. Bibcode:2010JChEd..87.1050J. doi:10.1021/ed100764f. Archived from the original (Archived Reprint) on 2012-04-03.
  2. ^ "Collection: Barnabas Wood Papers". SCOUT at University of Tennessee, Knoxville. Retrieved March 22, 2022.
  3. ^ G. W. A. Milne, ed. (2005). Gardner's Commercially Important Chemicals: Synonyms, Trade Names, and Properties. John Wiley & Sons. ISBN 978-0-471-73661-5.
  4. ^ Khan F. M., Gibbons J. P. "The Physics of Radiation Therapy, 5th ed". Wolters Kluwer.
  5. ^ DeviantOllam (2019-05-01), Copying Keys via a Mold and Cast Attack, archived from the original on 2021-12-22, retrieved 2019-05-04
  6. ^ The Modern Rogue (2019-10-04), Duplicating a Key Using Molten Metal (with LockPickingLawyer), archived from the original on 2021-12-22, retrieved 2020-11-09
  7. ^ Sambamurthy, K. (2007). Pharmaceutical Engineering. New Age International. ISBN 9788122411690.
  8. ^ Do-Gyoon, Kim (February 2006). "Evaluation of Filler Materials Used for Uniform Load Distribution at Boundaries During Structural Biomechanical Testing of Whole Vertebrae". Journal of Biomechanical Engineering. 128 (1): 161–165. CiteSeerX 10.1.1.721.5864. doi:10.1115/1.2133770. PMID 16532630.
  9. ^ a b "Wood's Metal Safety Data Sheet". Flinn Scientific. Retrieved 7 October 2024.

Bibliography

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  • Birchon's Dictionary of Metallurgy, London, 1965
  • Experimental techniques in low-temperature physics, G. K. White, Oxford University Press, Third Edition
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