Düşük Yayıcı Kaplama Tasarımı, Hazırlanması ve Karakterizasyonu

Abstract

More than 40% of the energy produced in many countries is being used for the heating and cooling of buildings. Reduction of the energy consumption in the buildings is possible by controlling the transmission and reflection of infrared radiation from the window glasses. The purpose of using low emissivity coating, which is one of the energy-efficient glass coatings, is to reduce the heat transfer between the indoor and outside environments. In this thesis, low emissivity coatings having dielectric/metal/dielectric (D/M/D) confiquration were designed and prepared. Titanium nitride (TiNx) or silver (Ag) thin films prepared at different growth conditions were used as the metalic/metal layer, while diamond-like carbon (DLC) or aluminum-doped zinc oxide (AZO) thin films were used as the dielectric layer of low emissivity coatings. The TiNx and DLC thin films were grown on glass subtrates by using DC magnetron sputtering technique, while the Ag and AZO thin films were grown using RF magnetron sputtering technique, The optical and structural characterization of the films were performed. The effects of growth conditions on the optical properties, bonding properties, microstructure, phase components and infrared emissivity of the films were investigated by UV–VIS–NIR spectrophotometery, XPS, Raman spectroscopy, SEM, AFM, XRD and FTIR measurements. The variation of optical constants with wavelength, sheet resistances and thicknesses of the TiNx, Ag, DLC and AZO thin films were determined by simultaneous fitting of the measured optical transmission and reflection spectra (for both s and p polarized light) to appropriate theoretical optical models, The film thicknesses and sheet resistances obtained by this method were verified, respectively, with profilometry and standard four point probe techniques. The effects of film growth conditions on the infrared optical reflectivity of AZO thin films were investigated in detail. Optimum growth conditions were specified for the films to be used in the low emissivity coatings as the metal and dielectric layers, and those films were deposited on glass substrates in D/M/D configuration to produce low emissivity coatings with different metal (TiNx or Ag) and dielectric (DLC or AZO) layers. The low emissivity performances of these coatings (high visible light transmision and low infrared emisivity) were compared to each other and to that of low emissivity coatings available in the literature. In this study, the smallest value of emissivity (ϵ=0.027) was obtained for the low emissivity coating of AZO/Ag/AZO configuration. This coating has an optical reflectivity of approximately 97% in the long-wavelength thermal radiation region and an average optical transmittance of approximately 75% in the visible region. Due to these properties, this coating could be used in the window glasses of energy-efficient buildings.