Christoph Baumann

High temperature tribology is considered to begin from a minimum temperature of 300–350 °C, where organic base oils and polymers begin to decompose, until a temperature of 1000 °C. In this field of tribology, tests are typically run under dry or solid-state friction, unless a solid lubricant is used, since most lubricants will oxidize or break down when exposed to these extreme temperatures. Therefore, this form of tribotesting is useful to determine the friction, wear, and other tribological characteristics of coatings, ceramics, alloys, cermets, and similar materials. Additionally, high temperature tribology is important to further understand the frictional interactions and adhesive behavior of contacts that operate at these high temperatures. When considering measurements of the tribological parameters in a high temperature application, the standard Schwingung, Reibung, Verschleiž (SRV) (Oscillating, friction, wear, in English) reciprocating, linear-oscillatory tribometer can be modified for testing temperatures of up to 1000 °C by using a high temperature heating block. With this configuration, the instrument can accurately monitor many parameters of the tribosystem, such as coefficient of friction, electrical resistance, zero stroke point, sliding speed, and others. As a result, the SRV instrument is shown to be a powerful tool for high temperature tribotesting. This paper will provide an overview of this high temperature tribology test rig and will discuss its versatility and efficacy, and will show how it can effectively be implemented in both research and practical applications for the development of various coatings and other high temperature tribological contacts.

The piston group is responsible for contributing to ~50% of the frictional losses of an engine, which ultimately leads to the waste of fuel. This coupled with the fact that gasoline is a finite resource linked to CO₂-emissions, there is an increased demand of higher performance vehicles, which coincidently further loads the piston ring. As of yet, there are plenty of studies that already study the piston ring’s contact with the cylinder liner. However, this study focuses on a cost-effective Schwing, Reib, Verschleiss (SRV) instrumentation that allows to pre-screen lubricants, additives, materials and coatings for their friction, wear and load carrying capacity including scuffing resistance. As a result of the pre-screening conducted outside of engine by using the SRV instrument, it brings us to the following conclusion: the PVD CrN-TiN 1º Group coating on the piston ring produces the least wear, as well as the lowest coefficient of friction. Moreover, it is concluded that a coating that is based from CrN and TiN allows the piston ring to perform better in engine settings. A continued understanding of the piston-cylinder-contact assembly only helps engineers, scientists and any other stakeholder to improve on the piston ring and cylinder liner interaction.