Prozeßidentifikation beim Plasmaspritzen temperatursensitiver Werkstoffe mit Hilfe einer Infrarot-Hochtemperatur-Thermokamera

Process-Identification at Plasma Spraying Thermally Sensitive Materials Using an Infra-red Thermal Imaging System Nowadays so called thermally sensitive materials are deposited by thermal spray techniques. Due to the high temperature process an undesired alteration (evaporation, chemical decomposition) of the material could occur. Therefore, optimisation of the deposition based only on empirical methods may be deremental with respect to the coating properties. This study shows the potential of an IR thermal imaging technique as a process control for evaluation and optimisation of the deposition through better understanding of the thermal spray process. The spray trials presented are based on preliminary examinations carried out with diagnostic tools. Therefore it was possible to achieve defined air plasma sprayed coatings of hydroxyapatite with different coating and component properties. This is particularly of interest, since there exists only a standard for hydroxyapatite as starting material but not for plasma sprayed coatings. Hence the coatings had either high or low contents of undesired phases, different degrees of cristallinity and bond strengths-varying from 5 to 42 MPa. Besides the power levels and the way to obtain the power the carrier gas flow significantly influences the properties of the coatings.