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The Sound Of The Perfect Coating

Sound waves can reveal surface properties. Parameters such as surface or coating quality of components can be analyzed nondestructively using lasers and sensors. In research and some industrial laboratories, this laser-induced surface wave spectroscopy has already become an established measurement technology.

Principle of the LAwave method using laser induced surface waves

“This technology enables us to examine coatings and surfaces non-destructively, quickly, and very accurately,” explains project manager Dr. Stefan Makowski, who heads the Coating Characterization Group at Fraunhofer IWS. “With LAwave, we are now taking the step towards industrial application.” Specific fields of application can be automotive engineering, surface coating and microelectronics. For instance, laser-induced surface acoustic wave spectroscopy can evaluate cracks and pores on thermally sprayed surfaces without destroying the component, as with conventional cross-sectional examinations. Removing damage layers on silicon surfaces can be examined in the semiconductor industry. LAwave technology provides a suitable method for quality control of PVD coatings, such as wear-resistant and friction-reducing coatings made of diamond-like carbon on motorcycle chains and engine components.

Potential for Environment and Health

Laser beam and sensor on a coated brake disc

LAwave-supported analysis of the latest brake disc generations opens up great potential for protecting the environment and health: The vehicle industry is gradually moving towards coating steel discs with particular coatings of hard metal, ceramic, or other materials to reduce abrasion and corrosion. This should ensure that cars and motorcycles meet the EU’s increasingly strict particulate matter limits. On the other hand, manufacturers are preventing unwanted side effects by switching to electric drives: Electric vehicles often only use the engine brake to recharge their batteries via recuperation. They use the conventional wheel brakes less often – and these consequently corrode earlier. The additional layers mentioned above can significantly reduce both problems, although they cannot yet be tested non-destructively. This is where LAwave steps in.

Continuous Development and Improvement

Early measurement systems of this type required complicated evaluation and were usually only operated by specialized scientists. Over the past 20 years, universities and non-university institutes have used those systems. Since then, however, Fraunhofer IWS has continuously developed and improved the technology and software and collaborated with partners to improve the design’s user-friendliness. A cooperation between Fraunhofer IWS and the Chair of Technical Design at the Technical University of Dresden (TUD) contributed to this.

Fraunhofer IWS is currently developing further technological improvements to open up new fields of application for LAwave. For example, artificial intelligence can significantly improve the quality of analysis even further. A mobile LAwave measuring head also is on the agenda. Its design will allow the surface analysis of internally coated tubes, rollers, and other particularly heavy, large, or complex-shaped machine components that cannot be handled in a stationary device.

With ‘LAwave’, the Fraunhofer Institute for Material and Beam Technology IWS in Dresden will present the second generation of a user-friendly measuring device at the International trade fair for quality assurance “Control” in April 2024, which will pave the way into industrial practice.

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