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What Is Tin Pest?

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This is a blob of tin metal, the beta allotrope of tin.

This is a blob of tin metal, the beta allotrope of tin.

Jurii, Creative Commons License
Question: What Is Tin Pest?
Here is a look at what tin pest is, what causes and tin pest, and some historical significance of the phenomenon.
Answer: Tin pest occurs when the element tin changes allotropes from its silvery metallic β form to the brittle gray α form. Tin pest is also known as tin disease, tin blight and tin leprosy. The process is autocatalytic, meaning once the decomposition begins, it speeds up as it catalyzes itself. Although the conversion requires a high activation energy, it is favored by the presence of germanium or very low temperatures (approximately -30 °C). Tin pest will occur more slowly at warmer temperatures (13.2 °C or 56 °F) and cooler.

Tin pest is important in modern time, as most tin-lead solder has been replaced with solder containing primarily tin. Tin metal may spontaneously decompose into a powder, causing problems where the metal is used.

Tin pest has historical significance, too. Explorer Robert Scott sought to become the first to reach the South Pole in 1910. The tin soldered cans the team cached on their route were empty of kerosene, potentially from poor soldering, but possibly because tin pest caused the cans to leak. There is a tale of Napoleon's men freezing in the Russian cold when tin pest disintegrated the buttons of their uniforms, though this has never been proven to have occurred.

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