Scientists already know how to coat components with diamond-like carbon to minimize friction. But now Fraunhofer researchers have developed a laser arc method with which layers of carbon almost as hard as diamond can be applied on an industrial scale at high coating rates and with high thicknesses.

By applying carbon coatings to engine components such as piston rings and pins, fuel consumption can be reduced. “Systematic application of our new method could save more than 100 billion liters of fuel each year over the next ten years,” says Prof. Andreas Leson from the Fraunhofer Institute for Material and Beam Technology IWS in Dresden.

The team around Prof. Leson, Dr. Hans-Joachim Scheibe and Dr. Volker Weihnacht has succeeded in producing hydrogen-free ta-C coatings on an industrial scale at a consistent level of quality. These amorphous carbon coatings are significantly harder and thus more resistant to wear than conventional diamond-like coatings. “Unfortunately, you can’t just scrape off diamond dust and press it onto the component. So we had to look for a different method,” says Dr. Scheibe, who has spent over 30 years investigating carbon’s friction-reducing properties.

In a similar style to old-fashioned film projectors, the laser arc method generates an arc between an anode and a cathode (the carbon) in a vacuum. The laser arc method can be used to deposit very thick ta-C coatings of up to 20 micrometers at high coating rates. “High coating thicknesses are crucial for certain applications – especially in the auto industry, where components are exposed to enormous loads over long periods of time,” says Dr. Weihnacht.

The automotive and motorcycle manufacturer BMW is working intensively on the industrial-scale implementation of ta-C engine components in its various vehicle models with the aim of reducing their fuel consumption. Prof. Leson sees this as the first major step in using the laser arc method to save resources. And as a motorcycle aficionado himself, he also sees another positive effect stemming from this development: “The fact that our research is helping to make motorcycling more environmentally friendly eases my conscience every time I go for a ride,” he says, unable to suppress a smile.

Anh Tuan