
Tiny diamonds wrapped in graphene get rid of friction - tambourine_man
http://arstechnica.com/science/2015/05/tiny-diamonds-wrapped-in-graphene-get-rid-of-friction/
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globuous
For those interested, there actually a sub field of mechanics called Tribology
[1] that deals with friction, lubrication, wear, and more generally
interacting surfaces in relative motion. I was surprised when I took this
class in grad school because it actually involves some heavy math [2].

For instance, turns out you can model the lubricant's motion by simplifying
the Navier-Stokes equations using a few assumptions [3] in order to get the
Reynold equation, notably:

\- the oil film mass is negligeable

\- because the film is thin, you can assume constant pressure in it

\- the classic no slip boundary condition

\- because the fluid's characteristic length (it's thickness) is negligeable,
you assume the flow to be laminar

\- inertial forces and surface tension is negligeable compared to viscous
forces

\- newtonian fluid [4]

\- etc...

EDIT: This wasn't entirely relevant to the article, but I thought it was kinda
cool and worth mentioning :)

[1]
[http://en.wikipedia.org/wiki/Tribology](http://en.wikipedia.org/wiki/Tribology)

[2]
[http://www.nptel.ac.in/courses/112102015/26](http://www.nptel.ac.in/courses/112102015/26)

[3] [http://tinyurl.com/lvshdp7](http://tinyurl.com/lvshdp7)

[4]
[http://en.wikipedia.org/wiki/Newtonian_fluid](http://en.wikipedia.org/wiki/Newtonian_fluid)

------
stereo
It stops working above 30% relative humidity, so practical applications are
unfortunately still far off.

~~~
beloch
It could work in a sealed system, such as a hard-drive bearing or a flywheel
similar to what is used in some hybrid vehicles.

Flywheels are a pretty exciting application actually. They're basically
mechanical capacitors. The upper limit on the energy they can store is
determined by the tensile strength of the material used for the rotor, but the
bearings the rotor spins on are responsible for how long energy can be stored
before being transformed into heat. Magnetic bearings are far more efficient
than mechanical bearings, but are costly to implement. A mechanical bearing
system with a graphene and nano-diamond coating could allow us to produce
flywheels that are simple, cheap, and able to store energy for a long period
of time. This might even make flywheels a viable alternative to chemical
batteries in some applications.

