The Layer Master

Pioneers – Prof. Dr. Robert Vaßen

June 2026

A Hall of Famer

Few researchers have done more to make ceramic high-temperature coatings matter in the real world than Prof. Robert Vaßen. Today, he is Deputy Director of the Institute of Energy Materials and Devices – Materials Synthesis and Processing (IMD-2). But his route into thermal spraying began with doubt, not devotion. What first looked to him like a rough, empirical craft eventually carried him into the technology’s Hall of Fame.

In this interview, Vaßen talks about international benchmarks, the long road from laboratory insight to aero engines, and why science sometimes advances fastest when someone is willing to try the apparently unreasonable.

Honored

Robert Vaßen has received numerous distinctions throughout his career, including the 2025 Böttger Medal awarded by the Deutsche Keramische Gesellschaft

Professor Vaßen, as a Hall of Famer, was thermal spraying love at first sight?

Not at all. My first real encounter with materials came during my doctoral work on fusion reactors. When I later began developing new thermal barrier coatings, I was actually rather sceptical of thermal spraying. It seemed coarse to me, and very empirical.

But the longer I worked with it, the more it drew me in. In 2017, I was inducted into the Thermal Spray Hall of Fame, one of the highest honours in the field.

You helped turn an empirical process into something researchers could understand from first principles. What was the breakthrough?

One milestone was our work on pyrochlore-based thermal barrier coatings. The key paper has now been cited more than 1,600 times. We found that these coatings perform far better when they are combined with an underlayer of yttria-stabilised zirconia.

That led us to a double-layer system that has become a global standard in many thermal barrier coating designs. We also built cyclic test rigs to examine how these coatings behave over long periods. Today, internationally renowned industrial companies use those facilities.

Rolls-Royce Germany became particularly interested in our work. After many years of close collaboration, we developed a magnesium spinel-based coating system that is now used successfully in aircraft turbines, including the Rolls-Royce Trent XWB.

How do you get from fundamental research to something industry can actually use?

By understanding the material deeply. My background is in physics, and that shaped me. I never wanted to rely on trial and error alone. I wanted to understand how microstructure and properties are connected.

Bringing research and application together is a powerful way to do that. The Rolls-Royce project is a good example: it began with a concrete technological need and ended with a technology that entered serial production.

“I never wanted to rely on trial and error alone. I wanted to understand how microstructure and properties are connected.”

— Prof. Robert Vaßen

Were there setbacks?

Of course. Technology transfer takes time, and industry does not always have the patience for long development cycles. If support for one route suddenly ends, you have to find new partners or alternative technologies quickly.

Personally, I also had to learn to delegate more. My instinct has always been to take on too much myself.

Beyond turbines, where else can thermal spraying make a difference?

Increasingly, I use it in technologies for the energy transition, especially PEM and alkaline electrolysis. We are developing coating systems that could reduce the need for expensive titanium and scarce precious metals.

PS-PVD, short for Plasma Spray–Physical Vapour Deposition, will remain an important technology. It will find its market. In China, this route is already being pursued on a very large scale.

You have supervised more than 75 doctoral researchers. What keeps that work interesting?

Working with young scientists is enormously energising. I enjoy passing on knowledge, but I also learn from their new and unconventional ideas.

And it is deeply satisfying to see them go on to build successful careers of their own, mostly in industry.

What advice would you give the next generation?

Try to understand unexpected results at a fundamental level. Very often, that is where new discoveries begin. Question standard explanations. They can broaden your horizon, but they can also hide misconceptions.

Keep your enthusiasm for science, and do not be afraid to try crazy ideas. At the same time, learn to say no, so routine work does not swallow all your time.

And most importantly: be fair and kind to your colleagues and the people around you. Treat others as you would like to be treated yourself. Good collaboration is not only more enjoyable. It is also more efficient.

Visit Jülich Thermal Spray Center

_{Source: Jürgen Lösel; Oliver Walterscheidt}

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