Fabrication of high infrared reflective textiles by magnetron sputtering technology Miao Dagang

Abstract

The growing demand for energy conservation in recent years has been accompanied by an increasing interest in high infrared reflective textiles for heat shielding applications. Traditional heat shielding textiles are mainly produced by laminating a layer of metal onto the fabric. However, there are few scientific studies on producing high infrared (IR) reflective textiles through coating of nano films onto textiles. Therefore, in this project, the aim is to fabricate and investigate innovative high IR reflective textiles by using magnetron sputtering technology.A systematic investigation is presented in this project, where aluminum doped zinc oxide (AZO)/Ag/AZO multilayer films are deposited onto polyester fabric to obtain a high IR reflectance on its surface. In the study, the surface morphology, crystal structure, chemical composition, ultraviolet (UV)-visible transmittance, electrical and IR properties of the prepared samples are investigated by using Atomic Force Microscopy, Scanning Electron Microscope, X-ray Diffraction, Spectrophotometer, a four-point probe system and Fourier Transform infrared spectroscopy, respectively. An examination of the coated films shows that:(1)AZO films with a highly c-axis oriented wurtzite structure are successfully prepared by using radio frequency (RF) magnetron sputtering. The average visible transmittance and IR reflection rates (from 1.5 to 25 μm) of the deposited films are 84.8% and 30%;(2)among all of the structures based on AZO and Ag films, the AZO/Ag/AZO sandwich structure exhibits the property of having the highest IR reflection. The AZO/Ag/AZO multilayer film with AZO layers that are 30 nm in thickness and an inner layer of Ag that is 15 nm in thickness shows the highest rate of IR reflection of 97% on a glass substrate and 96% on a PET substrate. In this multilayer film, the inner layer of Ag starts to form a continuous film at a thickness of around 10 nm. The thickness of the Ag layer is also inversely proportional to the film sheet resistance and directly proportional to the IR reflection rate of the film.(3)In the AZO/Cu/AZO films, the inner layer of copper (Cu) starts to form a continuous film at a thickness of around 11 nm. The AZO/Cu/AZO film samples exhibit a visible transmittance of 60% -80% and the sample with a Cu inner layer of 15 nm in thickness shows the highest rate of IR reflection of 67% in the far infrared radiation (FIR) region; and (4)the polyester fabrics coated with AZO/Ag/AZO films (with an Ag inner layer that is 15 nm in thickness) have good water resistance (CA=91.5°) and superior air permeability (17.1 ml/s/cm² at 100 Pa) compared to the polyester fabric without any coating. The coated fabrics also exhibit excellent UV protection from UV radiation (UPF=40.64), and demonstrate a high rate of IR reflection of 95% -96%.The high IR reflectance and unique properties of AZO/Ag/AZO coated polyester fabrics make them a promising candidate for use in high IR reflective textile products in the future.