Characterization Of Er₂O₃ And Al₂O₃ Composite Films Prepared By Magnetron Sputtering

In this thesis,the mixed phase Er2O3(M-Er2O3),pure cubic phase Er2O3(C-Er2O3),Er2O3/Er composite films and SiC particle doped Al2O3 composite films were prepared by magnetron sputtering.The effect of micro structure on the properties,Er interlayer on the structure and properties of Er2O3 film deposited on steel subustrate and doping content of SiC on Al2O3-xSiC composite films were characterized by confocal micro Raman spectrometer,X-ray diffractometer,scanning electron microscope,energy dispersive X-ray spectrometer and nanomechanical probe,and so on.The main results are as follows:1.Erbium oxide coatings were prepared by mid-frequency pulsed magnetron sputtering at substrate temperatures of 350?,and post annealing at 700? in nitrogen for 2 h.The as-deposited coating was composed of mixture of monoclinic and cubic phases,while the annealed coating was a pure cubic phase.Vibration modes of monoclinic Er2O3 was identified and well assigned.2.By comparing and analyzing the spectra of the M-Er2O3 and C-Er2O3.four distinct differences of fluorescence spectra between C-Er2O3 and monoclinic Er2O3(B-Er2O3)were discovered.Based on the features,rapid phase identification of Er3+containing cubic or monoclinic rare earth sesquioxides can be carried out at room temperature.3.Based on the power-dependent fluorescence spectrum,the luminescent mechanism of Er2O3 under 532 nm excitation and the influence of the phase structure and crystal size on the luminescent mechanism are discussed.The relationship between the microstructure and the thermal conductivity of the film is obtained from the ratio of the hypersensitive transition green luminescence to the conventional green luminescence.4.Based on the temperature-dependent Raman spectrum,the thermal conductivity of C-Er2O3 nanocrystalline film on isotropic steel substrate is obtained by film/substrate double-layer structure heat conduction equation analytical analysis.At the same time,A method for determining the thermal conductivity of film deposited on anisotropic substrate system combining micro-Raman method with simulation and optimization conducted by COMSOL Multiphysics(?)is proposed.5.The effect of Er interlayer on the microstructure,mechanical and electrical properties of Al2O3 coating were clarified,it was found that the key to improving the thermal stability of Al2O3 coating is to effectively avoid the oxidation of metal substrate in the subsequent oxide film preparation and to hinder or delay the mutual diffusion between oxide and substrate.6.SiC doping can obviously reduce the surface roughness of Al2O3-xSiC composite coating,refine the grains of Al2O3 matrix,and improve the high temperature integrity of Al2O3.Due to native narrower band gap of SiC compared with Al2O3,the insulation properties of the composite coating are deteriorated by the addition of SiC,but the samples with 3.4at%of the addition still meet the insulation requirements of ITER.Annealing at 900? promoted the crystallization of SiC particles,and the hardness and elastic modulus of the composite films with dope concentration of 3.4at%were increased by 62%and 25%,respectively.However,when the content of SiC was higher than 14at%,the mechanical properties were obviously deteriorated.