Theoretical Modeling and Analysis of Directional Spectrum Emissivity and Its Pattern for Random Rough Surfaces with a Matrix Method

Jianrui Hu,Bing Wang,Jinfu Zhao,Zhanqiang Liu,Qinghua Song

doi:10.3390/sym13091733

Abstract

The emissivity is an important surface property parameter in many fields, including infrared temperature measurement. In this research, a symmetry theoretical model of directional spectral emissivity prediction is proposed based on Gaussian random rough surface theory. A numerical solution based on a matrix method is determined based on its symmetrical characteristics. Influences of the index of refraction n and the root mean square (RMS) roughness σrms on the directional spectrum emissivity ε are analyzed and discussed. The results indicate that surfaces with higher n and lower σrms tend to have a peak in high viewing angles. On the contrary, surfaces with lower n and higher σrms tend to have a peak in low viewing angles. Experimental verifications based on infrared (IR) temperature measurement of Inconel 718 sandblasted surfaces were carried out. This model would contribute to understand random rough surfaces and their emitting properties in fields including machining, process controlling, remote sensing, etc.

Highlights

As a surface property parameter, the precise determination of emissivity is important in many fields, including infrared temperature measurement
The effects of the index of refraction n and the root mean square (RMS) roughness σrms on the emissivity ε are discussed by setting different parameters
The values of n and σrms is chosen inside this range by proportional sequences, to cover the majority of rough surfaces encountered in industry

Summary

Introduction

As a surface property parameter, the precise determination of emissivity is important in many fields, including infrared temperature measurement. The indirect influences of temperature, wavelength and other factors on emissivity can be experimentally measured and are relatively clear. Studies on Pt-10Rh and SiC indicate that the emissivity of rough surface increases with the increase of temperature and the decrease of wavelength [6]. Other factors including chemical composition [1], heat treatment [2,3] and oxidation [10,11] may have an effect on emissivity.

Methods

Results

Conclusion