The High-Temperature Resistance Properties of Polysiloxane/Al Coatings with Low Infrared Emissivity

Jun Zhao,Xiaolong Weng,Lun Qi,Yan Huang,Wei Luo,Gang Huang,Le Yuan

doi:10.3390/coatings8040125

Abstract

High-temperature-resistant coatings with low infrared emissivity were prepared using polysiloxane resin and flake aluminum as the adhesive and pigment, respectively. The heat resistance mechanisms of the polysiloxane/Al coating were systematically investigated. The composition, surface morphology, infrared reflectance spectra, and thermal expansion dimension (ΔL) of the coatings were characterized by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy, and thermal mechanical analysis (TMA), respectively. The results show that thermal decomposition of the resin and mismatch of ΔL between the coating and the substrate facilitate the high temperature failure of the coating. A suitable amount of flake aluminum pigments could restrain the thermal decomposition of the resin and could increase the match degree of ΔL between the coating and substrate, leading to an enhanced thermal resistance of the coating. Our results find that a coating with a pigment to binder ratio (P/B ratio) of 1.0 could maintain integrity until 600 °C, and the infrared emissivity was as low as 0.27. Hence, a coating with high-temperature resistance and low emissivity was obtained. Such coatings can be used for infrared stealth technology or energy savings in high-temperature equipment.

Highlights

Low infrared emissivity coatings are usually composed of a polymer binder and functional particles, which are widely applied for both energy savings and infrared camouflage due to their low emissivity, cheap cost, and simple construction technology [1,2,3,4]
The composition, structure, and infrared emissivity of the coatings at high temperatures were systematically studied by Thermogravimetric Analysis (TG), IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermal mechanical analysis (TMA), respectively
The morphology and XPS spectrum of samples were characterized by field emission scanning electron microscopy (FE-SEM, JEOL JSM-7600F, Tokyo, Japan) and X-ray photoelectron spectroscopy (XPS, Escalab 250Xi, Waltham, MA, USA), respectively

Summary

Introduction

Low infrared emissivity coatings are usually composed of a polymer binder and functional particles, which are widely applied for both energy savings and infrared camouflage due to their low emissivity, cheap cost, and simple construction technology [1,2,3,4]. As aircrafts achieve higher velocity flights, their exterior surface temperatures rapidly increase This necessitates broader temperature requirements for low infrared emissivity coating [5,6,7]. Xiao [7] prepared a low infrared emissivity coating with modified silicone resin and flake aluminum powder for the adhesive and pigment, respectively. The composition, structure, and infrared emissivity of the coatings at high temperatures were systematically studied by Thermogravimetric Analysis (TG), IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermal mechanical analysis (TMA), respectively. These results were combined to explain the high-temperature failure mechanism (both the mechanical and optical failure). The results provide theoretical guidance for future design of low emissivity coatings with high-temperature resistance

Materials

Heat Treatment

Characterization

Results and Discussion

Conclusions