BEYOND SURFACES

Spot on: application According to the German Gesellschaft für Tribologie (GfT, Society for Tribology; www.gft-ev.de) , friction and wear in industrialized countries causes annual losses of 2–7% of the gross national product. And a study published last year by the GfT concludes that in the mobility sector in Germany alone, almost 22 million tonnes of CO 2 could be saved by 2030 by reducing friction. Minimizing wear through coatings Design engineers try to minimize wear caused by friction by optimizing the design of components. Other important factors are the material composition and lubricating media, such as oil, grease or water. It is often even more efficient to coat component surfaces: › › The SUMEBore coating technology developed by Oerlikon Metco ensures lower friction, increases corrosion resis- tance and reduces wear in cylinder bores in combustion engines. This allows fuel savings of 2–4%. Oil consumption is reduced by up to 30%, and in locomotive diesel engines, that can rise to 75%. › › Compared to conventional solutions, coat- ings from Oerlikon Balzers reduce friction in race car chassis front suspension tubes by up to 20%. › › PVD coatings from Oerlikon Balzers on valves for the oil and gas industry reduce the friction coefficient by up to a factor of five compared to steel (COF: ~0.05). When we rub our hands to warm them up on cold days, this sliding friction is definitely desirable, and without the static friction between the tires and the road, a car would not be able to drive around a bend. Less pleasing, however, is rolling friction, which hampers smooth progress on straight sections. Frictional forces — whether desired or not — counteract the motion of two bodies and inhibit or even prevent it. The cause lies in their surface properties, because even if a microscope is sometimes required to see the irregularities, apparently smooth surfaces are still rough and “get caught” on each other. Less friction = lower costs and less CO 2 There is a fundamental relationship between friction and wear. Consequently, compo- nents’ performance and service life depend decisively on their frictional behavior. Quite a bit of friction potential In one of the first physics lessons at school, we learned: When there is motion between two bodies in contact, friction occurs. Scientists study how this effect can be utilized — or avoided. Coatings play a decisive role here. Beyond SURFACES 02|2020 32