Solid lubricant

Solid lubricants reduce the friction caused by the particles or platelets they contain, which slide easily on one another.

Graphite and molybdenum disulfide are often used, as well as finely distributed non-ferrous metals , ceramic particles ( titanium nitride ) or plastics such as PTFE ( Teflon ). The soft metals are such. B. aluminum , copper , lead , indium , tin , at higher temperatures also gold , platinum and silver .

These lubricants are often used as additives for lubricating greases and at lubrication points that are subject to high thermal loads. As a release agent , solid lubricants improve the emergency running properties .

Hot screw compounds reduce z. B. as assembly pastes the risk of blocking due to corrosion or cold welding of the bare metal surfaces of exhaust or spark plug threads or they keep screw connections of vehicle brakes common without flowing on the surface when heated.

Graphite, MoS ₂ and ceramics are also offered as additives to engine oil . However, the engine manufacturers often do not approve these additives.

In automotive engineering, copper paste is often used for spark plug threads and for fastening disc brakes. However, it would be preferable to use graphite or other solid lubricants, since brake calipers and cylinder heads are usually made of aluminum, so that, under the influence of moisture, together with copper, bimetal corrosion can occur.

Solid lubricants are used to lubricate roller bearings when special operating conditions (e.g. vacuum, high temperatures, centrifugal forces, ionizing radiation in nuclear and space technology) make oil lubrication impossible.

Bullets coated with MoS ₂ are used to reduce the barrel wear of sporting weapons and to increase the muzzle velocity for the benefit of greater precision.

literature

• Hans-Jürgen Blanke, Wilfried J. Bartz, Uwe Jens Möller: Expert Practice Lexicon Tribology Plus. 2010 Terms for study and work, 2nd edition, Expert Verlag, Renningen 2000, ISBN 3-8169-0691-5 .
• Jobst H. Kerspe: Tasks and procedures in surface treatment. Expert Verlag, Renningen 2000, ISBN 3-8169-1647-3 .
• Herbert Birkhofer, Timo Kümmerle: Solid-lubricated rolling bearings: Use, principles and design , Springer Verlag

Individual evidence

1. ↑ Werner B. Schneider (Ed.): Article from the series Paths in Physics Didactics , Volume 1, Collection of Current Articles from Research in Physics Didactics, p. 88f, Arbeitskreis Bavarian Physics Didactics, ISBN 3 - 7896 - 0090 - 3, Verlag Palm & Enke, Erlangen 1989.
2. ↑ Kirsten Bobzin: Surface technology for mechanical engineering , publishing house John Wiley & Sons.
3. ↑ FAG-Kugelfischer, Lubrication of Rolling Bearings , page 33 (PDF; 989 kB).

Web links

• White solid lubricants (accessed August 16, 2016)
• Oil-free gear lubrication with polytetrafluoroethylene solid lubricants (accessed on August 16, 2016)
• Base oils, greases and solid lubricants (accessed August 16, 2016)