On the heating and temperature measurement for high temperature emissivity analyses of coatings

M. Honner1, P. Vacikova1 and J. Martan1

1University of West Bohemia in Pilsen, Czech Republic

Keywords: high temperature, temperature measurement, heating
property: emissivity
material: coatings

The contribution introduces a new experimental set-up for the measurement of high-temperature spectral-distribution of emissivity of thick coatings. The method is based on a typical arrangement using FTIR spectrometer analyzing the radiation of the laboratory blackbody and sample surface. Rotating mirror in between the blackbody and sample is used to change the optical path into the spectrometer emission port. Some new approaches concerning the method applicability for high temperature analyses of thick coatings has been developed and tested.

Regarding the sample heating the method is designed to fulfill especially the following requirements. The temperature range is required up to 1200 °C with high uniformity of the sample temperature field. Duration of analyses could be as short as possible as a large number of samples and temperature steps are expected. Thus two different arrangements have been tested and the results are reported. The first one uses parallel application of coatings directly on one exchangeable electrical resistance heating block, where the heating of several coatings proceeds together and the measurement is done in a sequence using the moving support of the heating block. The second one uses a high power laser with a galvo scanning head with defined movement of the heating spot in order to compensate the sample shape and cooling processes in order to ensure homogeneity of the sample temperature field.

Regarding the sample surface temperature measurement the application of infrared camera system together with a reference known-emissivity high-temperature coating has been tested. The use of the infrared camera allows analyzing the non-uniformity of the sample temperature field. The application of the reference coating is proposed to overcome the problem with unknown temperature drop on the thickness of the analyzed coating and has been studied also with the help of computer simulation. Moreover the reference coating can be used for a relatively fast comparative emissivity analysis among samples.

Details about the mentioned set-ups and results of their application for the emissivity measurements are going to be reported. Advantages and disadvantages are discussed.

     Official Sponsors

uni Anter_logo Tziolas_logo_ linseis netzsch