| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 105 === In recent years, the hard coating is required to have not only a high hardness, but also other multifunctional properties. The hard and transparent coating can be a protective layer to directly protect glass surface or metal thin film in many optical applications like reflecting mirror, heat mirror, and solar spectrally selective absorber coatings. The AlN, Si3N4, and BN are all the wide band gap materials and have high resistance to thermal and chemical environment. Among of them, AlN has good dielectric properties; Si3N4 has high fracture toughness; BN has excellent lubricating properties.
The (AlSiB)N coating was prepared by reactive magnetron sputtering of equal-molar AlSiB target in argon-nitrogen gas mixture at a substrate temperature of 400 ℃. The RF power input to the sputter target was 350 W and the nitrogen is mainly varied in this study. The thickness of the films was about 1 μm. The structure, morphology, mechanical and optical properties of the films were investigated in detail. Then, the film was annealed at 500 to 1300 ℃ for 2h in air to evaluate the oxidation resistance and phase transformation. Finally, the (AlSiB)N film was annealed from 800 to 1300 ℃ for 2h in the vacuum (5×10-5 Torr) to evaluate the thermal ability.
Regardless of RN, all the (AlSiB)N films were amorphous structure. When RN=30%, the hardiness, elastic modulus and fracture toughness were 24.3 GPa, 235.6 GPa and 1.454 MPa·m1/2, respectively. As the RN increases, the absorption edge shifted to shorter wavelength and thus widened the transmission window. The optical band gap of the (AlSiB)N films increases to 4.67 eV and has high transmittance of 90 % in visible light when the RN=30 %. In terms of oxidation resistance, oxidation resistance of the film was gradually enhanced with the continued increase in RN. At 900 ℃ , the film prepared at RN≧12 % exhibited an extremely low oxidation rate. As annealing temperature increased further, the rapid oxidation reaction occurred and the structure would transform into the mullite structure. In terms of thermal stability, the film sustained its amorphous structure, even after annealing at 1100 ℃. The defects and stress were decreased after annealing, causing that the absorption edge shifted to shorter wavelengths and band gap increase from 4.672 eV to 4.987 eV. The high transparent hard (AlSiB)N composite film is a potential candidate in optical, protective, and microelectronic applications.
|
|---|
