Abstract
Substrate temperature is nowadays recognized as a key parameter to optimise the coating quality in the thermal spraying process. Generally parts being processed are in motion and therefore non contact temperature measurement devices are appropriate. In contrast to thermocouples, optical pyrometers have several advantages. First, they are easy to install and second they do not bring any disturbance to the measured system. Meanwhile, several problems may arise with those devices which are not always considered as they should be and in particular the variation of material emissivity temperature, the effect of the reflection of the external radiation or the attenuation of the optical signal due to the variable transmissivity of the optical path. The aim of this work was to develop algorithms for correcting optical pyrometer temperature measurements during thermal spraying by taking into account emissivity variations and radiation reflexion on the components. Emissivity of some materials with respect to the specific spectral band of the pyrometer and the influence of reflected radiations were measured. Results are discussed in order to point out the influence of each parameter on the temperature value.
