We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
Published online by Cambridge University Press: 26 February 2010
Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get in.
Stephen LeacockA high-frequency induction coil can be used to heat, levitate and stir liquid metal. This has given rise to a number of metallurgical processes, some old (such as induction furnaces) and some new. In this chapter, we shall discuss five.
(i) Induction furnaces. These have remained virtually unchanged for the best part of a century, yet we are still unable to calculate reliably the stirring velocity within a furnace!
(ii) Cold crucible melting. This is an ingenious process which combines the functions of an induction melter and a continuous caster, all in one device.
(iii) Levitation melting. This is now routinely used in the laboratory to melt small specimens of highly reactive metals. Unfortunately, if the levitated drop becomes too large, it tends to drip.
(iv) The electromagnetic valve. This provides a non-contact means of modulating and shaping a liquid-metal jet. It is a sort of levitation melter in which the metal is allowed to leak out of the bottom.
(v) Electromagnetic casting. Some aluminium producers have replaced the casting mould in a continuous caster by a high-frequency induction coil. Thus, the melt pool is supported by magnetic pressure rather than by mechanical means. It is extraordinary that large ingots, which may be a metre wide and ten metres long, can be formed by pouring the liquid metal into free space and soaking it with water jets!
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.
