| The preparation methods of porous zirconia membrane and the application of alumina and zirconia coatings in carbon fiber strengthening epoxy resin composites were investigated in this dissertation. The phase components, thermal stability, microstructure and pore properties of porous membrane (ZrO2, YSZ and Al2O3-ZrO2 ) were characterized. The effects of coatings on the interfacial performance, mechanical property, thermal resistant property of composites were studied. The dissertation was mainly discussed as follows:The nanocrystalline of zirconia and yttria-stabilized zirconia (YSZ) were prepared by stearic acid method. The reaction process, crystalline phase and particle size of ZrO2 and YSZ particles treated at different temperatures were investigated. The ideal dispersion conditions of ZrO2 powders prepared in water were obtained by the study of dispersion behavior. Then, the supported YSZ membrane whose most concentrative pore diameter is about 87 nm was prepared and its pore diameters concentrate into 20~100nm.The stable YSZ sol and defect-free YSZ membranes supported by tube were firstly prepared by anionic exchange method using zirconyl chloride as raw materials. Results of nitrogen isothermal absorption measurement show that the most concentrative pore diameter of YSZ membrane calcined at 700C is less than 3 nm and is 3.8nm at 900C. It is found that the crystal phases of ZrO2 membranes from 400C to 600C are tetragonal, monoclinic ZrO2 appear at 700C and the crystal phases of 3mol% YSZ membranes are still tetragonal at 900 C by differential thermal analysis(DTA), X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FT-IR).The defect-free Al2O3-ZrO2 composite membranes supported by hollow fiber and ceramic tube were prepared by sol-gel process from aluminium iso-propoxide and zirconyl chloride as their precursors. The effects of mole ratio of alumina and zirconia in composite membranes on crystal temperature, crystal phase and pore structure were investigated in detail. The results show that the thermal stability of composite membranes is greatly improved compared to pure Al2O3 or ZrO2 membranes. When the mole ratio of alumina and zirconia ranged between 0.1 and 1, the crystal phase ofcomposite membranes is tetragonal ZrO2 until 1100C, but its main crystal phase is still tetragonal and monoclinic ZrO2 or monoclinic ZrO2 and alpha Al2O3 appear at 1200C. Results of nitrogen isothermal absorption measurement show that the most concentrative pore diameters of composite membranes calcined at 700 C with different mole ratio of alumina and zirconia concentrate into 4~5nm, but the specific surface areas and pore volume of composite membranes decrease with the increase of zirconia. It is found that most concentrative pore diameters of composite membranes with 50mol% zirconia are still about 4.3 nm and its specific surface areas decrease correspondingly when calcination temperatures increase from 700C to 1100C. However, the thermal stability of composite membranes is higher than 3mol% YSZ membranes prepared by our laboratory and reference, and gas permeation test showed that the membranes have gas selectivity.The homogenous alumina and YSZ coatings on carbon fiber were prepared by sol-gel method. The results of mechanical property analysis show that the interlaminar shear strength (ILSS) of alumina-coated carbon fiber reinforced epoxy resin composites is enhanced 17.7%, the ILSS of YSZ-coated carbon fiber composites is enhanced 52.0% compared to uncoated carbon fiber composites, and bending strength and tensile strength are improved slightly at the same time. The results of thermogravimetric analysis show that alumina and YSZ coatings on carbon fiber can effectively slower the weight loss rate of composites resulting from oxidation in the range of 3 50 C to 700 C.
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