Porcelain
Electric insulators

Porcelain has been used for electrical insulators since at least 1878, with another source reporting earlier use of porcelain insulators on the telegraph line between Frankfurt and Berlin. It is widely used for insulators in electrical power transmission system due to its high stability of electrical, mechanical and thermal properties even in harsh environments.

A body for electrical porcelain typically contains varying proportions of ball clay, kaolin, feldspar, quartz, calcined alumina and calcined bauxite. A variety of secondary materials can also be used, such as binders which burn off during firing. UK manufacturers typically fired the porcelain to a maximum of 1200 °C in an oxidising atmosphere, whereas reduction firing is standard practice at Chinese manufacturers.

In 2018, a porcelain bushing insulator manufactured by NGK in Handa, Aichi Prefecture, Japan was certified as the world's largest ceramic structure by Guinness World Records. It is 11.3 m in height and 1.5 m in diameter.

The global market for high-voltage insulators was estimated to be worth US$4.95 billion in 2015, of which porcelain accounts for just over 48%.
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