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Slurry Flows
Slurry flows are
fluids with micro- or nano-sized particles suspended inside. Slurry
flows are traditionally used for such things such as chemical
mechanical polishing (CMP) of integrated circuits. and other
micro/nanoscale devices such as hard disk read/write heads.
Additionally, they are used in studied in farming technology, sediment
transport, and with debris flows. If the particles are harder than the
tribosurfaces, they could act as abrasives, as opposed to lubricants.
Powder
Flows
Powders, in general, are defined as a
collection of small discrete solid particles in contact, so as to
entrap gas in the spaces between the particles. As opposed to granules,
powder particles are usually no larger than approximately 1 mm. A key
property in the ability of powders to act as a lubricant between
surfaces in relative motion is that they can flow when a critical shear
stress, or yield stress is exceeded. This is known as powder
lubrication.
Granular Flows
A granular flow
is a multiphase (i.e., solid and fluid) flow consisting of particulates
and an interstitial fluid. When sheared the particulates may either
flow in a manner similar to a fluid, or resist the shearing like a
solid. The dual nature of these types of flows makes them very
difficult to analyze and even more difficult to model except for the
simplest cases. The PFTL studies granular flow lubrication.
Tribology
Tribology is
the study of friction, lubrication, and wear of interacting surfaces in
relative motion. Although it has been around for centuries, it formally
became a new field of science in 1967 by a committee of the
Organization for Economic Cooperation and Development [1]. "Tribology"
is derived from the Greek word "tribos" which means rubbing or sliding.
The word has nothing to do with the "the study of 'three' (3) types of
sciences", as many non-tribologists perceive.
Because the
field is highly multidisciplinary, it is quite diffuse, Students in
mechanical engineering, material science, chemistry, and chemical
engineering might not get exposed to it at the undergraduate level.
Additionally, nanotechnological devices are experiencing "proof
of concept"-preventing problems due to frictional interactions in
nanoscale interfaces. Thus, tribology professors have begun to see new
researchers entering their classrooms. From a mechanical engineering perspective,
most of our PFTL students fall in the area of "Thermal
Science/Fluids".
1.)
Stachowiak, G.W., and Batchelor, A.W, Engineering
Tribology, Butterworth Heinemann, Inc., Boston, 2001.
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