Thermal spray processes and in particular atmospheric plasma spraying (APS) and high velocity oxygen fuel spraying (HVOF) are flexible and industrially established coating technologies. Single layered coating systems are made from ceramics, metals or hard metals. Multilayers have an especially high application potential.
For example, by combining conductive and nonconductive coatings it is possible to apply heater elements of nearly any geometry directly to a part that requires heating. There are several advantages including the low profile of the heater elements, the possibility to cover a large area, and their direct contact to the part, which minimizes heat losses.
To generate heat from electrical energy the conductive coatings should have a defined and temperature stable resistance. Previously metallic materials were tried. However, the approach failed due to the thermal and oxidative damage, which limited the lifetime of the coatings.
A fully ceramic heater element was developed in cooperation with Fraunhofer Institute for Ceramic Technologies and Systems (IKTS). The DKG / AiF funded the project.