Emissivity model of steel 430 during the growth of oxide layer at 800–1100 K and 1.5 μm

• Published in: Infrared physics & technology 2018-01, Vol.88, p.23-31
• Main Authors: Xing, Wei, Shi, Deheng, Sun, Jinfeng, Zhu, Zunlue
• Format: Article
• Language: English
• Subjects: Emissivity model; Oscillation of spectral emissivity; Oxide layer; Steel 430; Temperature measurement
• ISSN: 1350-4495; 1879-0275
• DOI: 10.1016/j.infrared.2017.11.001

This work studied the variation in the spectral emissivity of steel 430 with growth of oxide layer at 1.5 μm over a temperature range 800–1100 K. In the experiment, the temperature was measured by the two thermocouples. The variation of spectral emissivity with growth of oxide layer was evaluated at a certain temperature. Altogether 11 emissivity models were evaluated. The conclusion was gained that the more the number of the parameters used in the models was, the better the fitting accuracy became. On the whole, all the PEE models, the four-parameter LEE model and the five-parameter PFE, PLE and LEE models could be used to well fit this kind of variation. The variation in the spectral emissivity with temperature was determined at a certain thickness of oxide film. Almost all the models studied here could be used to accurately evaluate it. The approximate models of spectral emissivity as a function of temperature and oxide-layer thickness were proposed. The strong oscillations of spectral emissivity were observed, which were affirmed to arise from the interference effect between the two radiations coming from the oxide layer and from the substrate. The temperature uncertainty generated only by the surface oxidization was approximately 4.1–10.7 K in this experiment. Experimental and fitting spectral emissivity curves of steel 430 versus the heating time at the temperatures of 820 and 900 K. [Display omitted] •Eleven emissivity models were evaluated.•Uncertainties in the temperature were approximately 4.1–10.7 K.•Variation in the emissivity with heating time was discussed at a certain temperature.•Variation in the emissivity with temperature was evaluated at a certain heating time.•Spectral emissivity as a function of heating time temperature was determined. This work studied the variation in spectral emissivity with growth of oxide layer at the different temperatures. For this reason, we measured the normal spectral emissivity during the growth of oxide layer on the sample surface at a wavelength of 1.5 μm over a temperature range 800–1100 K. In the experiment, the temperature was measured by the two thermocouples, which were symmetrically welded onto the front surface of specimens. The average of their readings was regarded as the true temperature. The detector should be perpendicular to the specimen surface as accurately as possible. The variation in spectral emissivity with growth of oxide layer was evaluated at a certain temperature. Altogether 11 emiss