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 fusible metal alloy (having a low melting point) that is useful for soldering and making custom metal parts. The alloy is named for Barnabas Wood, who invented and patented the alloy in 1860.[1][2] It is a eutectic 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] Its fumes are toxic, as well as being toxic on skin exposure.
Applications
[edit]
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
[edit]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[10] 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]
Related alloys
[edit]| 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 | 29.8 °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
[edit]- ^ 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.
- ^ "Collection: Barnabas Wood Papers". SCOUT at University of Tennessee, Knoxville. Retrieved March 22, 2022.
- ^ 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.
- ^ Khan F. M., Gibbons J. P. "The Physics of Radiation Therapy, 5th ed". Wolters Kluwer.
- ^ DeviantOllam (2019-05-01), Copying Keys via a Mold and Cast Attack, archived from the original on 2021-12-22, retrieved 2019-05-04
- ^ 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
- ^ Sambamurthy, K. (2007). Pharmaceutical Engineering. New Age International. ISBN 9788122411690.
- ^ 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.
- ^ a b "Wood's Metal Safety Data Sheet". Flinn Scientific. Retrieved 7 October 2024.
- ^ Genchi, Giuseppe (May 26, 2020). "The Effects of Cadmium Toxicity". NIH National Library of Medicine. Retrieved November 16, 2024.
Bibliography
[edit]- Birchon's Dictionary of Metallurgy, London, 1965
- Experimental techniques in low-temperature physics, G. K. White, Oxford University Press, Third Edition
External links
[edit]- Making your own low-melting point eutectic: Science Toys: A metal that melts in hot water
- Burdakin et al., "Melting points of gallium and of binary eutectics with gallium", Metrologia, 2008
Media related to Wood's metal at Wikimedia Commons
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