Change of Coefficient of Friction due to Ageing of Biological Esters

Abstract

In order to investigate the influence of a single tribo system on the ageing of lubricants, a so-called Tribo-Oxidationtest has been designed at IFAS. It consists of a disc on disc tribometer integrated into the pressure vessel of an oxidation test according to ASTM D 2112. The coefficient of friction µ of different friction partners is discussed in this paper. The attempts are done with biological esters which are synthesized in a collaborative research centre. Due to biological aspects they contain no additives. It has been shown that there is an influence of oil ageing on friction coefficient but also a big influence of viscosity on friction coefficient.

Tribological Performances of Diamond‐Like Carbon Coatings for Hydraulic Applications

“…The DLC coating film has a structure consisting of both sp2 and sp3 bondings. The internal stresses and film hardness depend on the ratio of sp2/sp3, allowing the film can be classified as either hard or soft DLC coatings depending on this ratio 5. The mechanical properties like hardness or the elastic modulus strongly depend on the relative amount of these two types of bonding.…”

“…In hydraulic applications, relatively thick coatings produced by thermal spraying methods or thin coatings produced by the physical vapor deposition (PVD) method are good alternatives to leaded bronze and brass [4][5][6]. Hydraulic systems often have high mechanical losses due to the high-power output, which is typically determined by the required speed and forces.…”