Application of indium tin oxide (ITO) thin film as a low emissivity film on Ni-based alloy at high temperature

Abstract

Indium tin oxide (ITO) films as the low emissivity coatings of Ni-based alloy at high temperature were studies. ITO films were deposited on the polished surface of alloy K424 by direct current magnetron sputtering. These ITO-coated samples were heat-treated in air at 600–900°C for 150h to explore the effect of high temperature environment on the emissivity. The samples were analyzed by X-ray diffraction (XRD), SEM and EDS. The results show that the surface of sample is integrity after heat processing at 700°C and below it. A small amount of fine crack is observed on the surface of sample heated at 800°C and Ti oxide appears. There are lots of fine cracks on the sample annealed at 900°C and a large number of various oxides are detected. The average infrared emissivities at 3–5μm and 8–14μm wavebands were tested by an infrared emissivity measurement instrument. The results show the emissivity of the sample after annealed at 600 and 700°C is still kept at a low value as the sample before annealed. The ITO film can be used as a low emissivity coating of super alloy K424 up to 700°C.