Overview
Thermal spray coatings protect critical components against wear, corrosion and high temperatures – for example in turbines, engines and industrial machinery. Whether a coating fulfils its function depends critically on two quality parameters: its thickness and its porosity. A coating that is too thin or too porous can shorten the service life of a component, while a coating that is too thick wastes material and process time.
Today, these parameters are usually verified only after the spraying process, often offline on test specimens or by destructive cross-section analysis. Deviations are therefore detected late, which may lead to rework, scrap and additional costs.
TSCENT proposes a novel technique that measures both thickness and porosity in a single measurement. The method can be integrated into the spray booth and delivers real-time feedback during the coating process. Furthermore, it is calibration-free and robust against the dusty environment of the spray booth.
The technique is based on sub-terahertz (sub-THz) radiation, which can penetrate ceramic coatings and requires no contact between sensor and sample. The interferometric response of the waves reflected at the coating surface and at the interface to the substrate, measured across a broad spectral range, allows the coating thickness to be determined. Sub-terahertz waves, with wavelengths in the sub-millimetre range, are scattered much less by dust particles than visible or infrared light. This makes the method robust under real production conditions. AI-based signal analysis supports the fast and reliable evaluation of the measurement data.
