Microstructure and properties of high emissivity coatings

Abstract

A new coating on lining in industrial furnace for energy saving has been developed. Properties and microstructure of the coatings were revealed by emissivity instrument, X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively. The result indicates that the emissivity of coatings is higher than 0.90 and the thickness of coatings is about 200 μm. ZrO₂, Cr₂O₃ and SiC in the coating benefit practical applications of coatings at high temperature with durable high emissivity and the continuous structure between the coatings and the substrate makes the coatings high cohesion and excellent adhesion for both specimens with and without sintering at high temperature. Result from laboratory experiment shows that the heating speed of specimen with coating is higher than that of controlled specimen and the temperature increases 30°C during the heating. The average temperature drop of specimen with coatings has a 13.5% improvement in the cooling speed. The application of coatings on the checker brick in a blast furnace of 1750 m³ indicates that the coating causes the blast temperature to an average increase of 28°C, reduces the fluctuation of blast temperature before the blowing-in and leads to a fuel saving of 10% approximately.