The Lubricant Alchemist

The Lubricant Alchemist

The small steel ball of the “Tribometer” measuring device slides over a steel disk 30 times per second, for two hours at 100 degrees Celsius and with a pressure of exactly 50 Newtons. In between is the thin film of an oil sample that is intended to demonstrate its lubricating properties. The depth of the scratches and notches on the steel disc shows how well the lubricant has done its job. “We use a total of 30 tribometers in our laboratories,” explains Nicole Dörr, scientific director of AC2T research GmbH, which has around 140 employees dedicated to testing and developing industrial lubricants. The institute, located in Wiener Neustadt, is not only the Austrian competence center for tribology (the study of wear, friction and lubrication of surfaces), but is also considered one of the most important in its field worldwide. “A modern engine oil consists largely of mineral oil, semi-synthetic or synthetic oil, as well as a proportion of additives that can be up to 25 percent,” says Dörr. Below is an overview of the tasks these additives are intended to fulfill:

• Verschleißschutz
• Reibungskontrolle
• Reinigung
• Alterungsverzögerung
• Säureregulierung
• Viskositätsstabilisierung
• Korrosionsschutz

An example of the enormous effort that goes into balancing the required lubricant properties is the neutralization of acids in the oil that arise due to the heavy use and high temperatures in an internal combustion engine. “We use finely ground lime powder as a balancing base reserve, which, however, cannot dissolve in the oil,” explains Dörr. Therefore, the calcium carbonate particles are coated with special detergent additives so that they can spread throughout the oil and neutralize the acids. Other, equally finely tuned additives take on the task of modifying viscosity. Without this, the oil would become too thick in cold temperatures and too thin in hot temperatures.

Another focus of research at AC2T is the investigation of oil aging and the associated effects on lubricity. In the laboratory, the aging process is simulated much faster than in real use by exposing the oil to high temperatures and additional oxygen. “We also carried out tests with engine oil from vehicles in everyday use and gained very interesting findings,” explains Nicole Dörr. Among other things, it turned out that the additive responsible for wear protection in a standard 5W30 oil was no longer detectable after just 6,000 kilometers, even with the best measuring devices. When asked whether the oil change intervals recommended by vehicle manufacturers are not far too generous, the chemist answers diplomatically: “From a purely technical point of view, more frequent oil changes would certainly be recommended, but ultimately you also have to take the economic component into account.”