Melt spinning
Encyclopedia
Melt spinning is a technique used for rapid cooling of liquids. A wheel is cooled internally, usually by water or liquid nitrogen
, and rotated. A thin stream of liquid is then dripped onto the wheel and cooled, causing rapid solidification. This technique is used to develop materials that require extremely high cooling rates in order to form, such as metallic glasses
. The cooling rates achievable by melt-spinning are on the order of 104–107 kelvin
s per second (K/s).
The concept of the melt spinner was developed by Pond and Maddin in 1969, whereby liquid was quenched on the inner surface of a drum, then later as a continuous casting technique by Liebermann and Graham. However the melt spinner is only able to produce small thin ribbon shaped specimens, some as thin as 10 micrometre
s. This limits melt spinning to mainly production of research specimens for alloys with high critical cooling rate, which are difficult to fabricate with other techniques.
Liquid nitrogen
Liquid nitrogen is nitrogen in a liquid state at a very low temperature. It is produced industrially by fractional distillation of liquid air. Liquid nitrogen is a colourless clear liquid with density of 0.807 g/mL at its boiling point and a dielectric constant of 1.4...
, and rotated. A thin stream of liquid is then dripped onto the wheel and cooled, causing rapid solidification. This technique is used to develop materials that require extremely high cooling rates in order to form, such as metallic glasses
Amorphous metal
An amorphous metal is a metallic material with a disordered atomic-scale structure. In contrast to most metals, which are crystalline and therefore have a highly ordered arrangement of atoms, amorphous alloys are non-crystalline...
. The cooling rates achievable by melt-spinning are on the order of 104–107 kelvin
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
s per second (K/s).
The concept of the melt spinner was developed by Pond and Maddin in 1969, whereby liquid was quenched on the inner surface of a drum, then later as a continuous casting technique by Liebermann and Graham. However the melt spinner is only able to produce small thin ribbon shaped specimens, some as thin as 10 micrometre
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
s. This limits melt spinning to mainly production of research specimens for alloys with high critical cooling rate, which are difficult to fabricate with other techniques.