Light-emitting coatings for protection against pirate products and as sensory elements

This article presents light-emitting coatings (LECs), a newly developed coating solution which offers the potential to extend the application spectrum of thermal spraying technology and cold gas spraying technology. The coating solution is based on the use of ceramic particles which can be exposed to radiation from an infrared laser and analysed in the visible range of the light spectrum with an optical evaluation unit (e.g. human eye or sensor) by initiating the anti-Stokes effect. For both spraying technologies, the incorporation of these particles into coatings permits new application fields, e.g. sensor equipment within wear protection coatings in order to signal the end of the service life (obz sensor) or for protection against pirate products (obz fingerprint). In this respect, one of the challenges is to integrate the temperature-sensitive marker particles into thermally sprayed coatings. Three spraying technologies (cold gas spraying, HVOF spraying and plasma spraying) were tested successfully. The application fields and products which are feasible for the utilisation of LECs are diverse, particularly in sectors which are critical to safety and quality or have high prices such as the automobile, medical technology, warehouse or pump industry.