Correlations between High-Temperature Oxidation Kinetics and Thermal Radiation Characteristics of Micro-Structured Nickel Surfaces Oxidized at 1173 K

Abstract

Micro-structured surface functional materials were widely used in electronics, batteries, solar cells, and many other products. However, oxidation at high temperatures greatly affects the material service life and performance. This study focuses on the oxide layer characteristics after high-temperature oxidation and the thermal emissivity of metal materials with micro-structured surfaces. Micro-structured surfaces with various groove morphologies were prepared on 99.9% purity nickel samples. The high-temperature oxidation characteristics of the nickel samples with the microstructure surfaces and the total hemispherical emissivities were measured after various oxidation times in high-temperature (1173 K) air to characterize the correlations between the micro-structure surface oxidization and the emissivity at elevated temperatures. The initial surface roughness greatly affects the surface roughness after oxidation with the oxidation increasing the surface roughness on smooth or less rough surfaces but making the surface smoother for very rough surfaces. The oxidation results show that rougher initial surfaces have larger oxide grain sizes with longer oxidation times leading to smaller grain sizes. The measured total hemispherical emissivity increased with the temperature (500–1400 K) and the oxide layer thickness. The experiments further illustrates that, for the same oxide layer thickness, the measured emissivities become larger for oxides with larger grain sizes caused by the rougher original surfaces. This analysis provides an understanding of the oxidation kinetics of microstructured surfaces and how the oxidized microstructure surfaces affect the thermal radiation properties.