| 其他摘要 | Hydrogen fugacity is one of the most important physicochemical parameters in high temperature high pressure hydrothermal systems, and it is critically important to in situ measure the hydrogen fugacity in hydrothermal systems. Some of perovskite based compounds are widely being researched for exhibiting high protonic conductivities at high temperatures in the presence of watervapour or hydrogen atmosphere. Among all of this perovskite based high temperature proton conductor, BaZrO3 based high temperature proton conductor is a promising candidate for solid electrolytes in hydrogen sensor for combining with the merits of good chemical stability and high proton conductivity. In the first phase, both sol-gel method and high temperature solid state method were used to synthesize BaZr0.9Y0.1O3-δ powders, and BaZr0.9Y0.1O3-δ powders prepared by both two methods were characterized using SEM, XRD and particle size analysis. The technics of sol-gel method is so complex that it should experienced solution, soliquid, gelatin, and then the gelatin was calcined at high temperatures. The BaZr0.9Y0.1O3-δ powders obtained were loose and porous, and the XRD patterns exhibited that the BaZr0.9Y0.1O3-δ powders may contained impurities. The synthesis technics of high temperature solid state method is a relatively simple process, after weighed and mixed, starting oxides were calcined at various temperatures. The BaZr0.9Y0.1O3-δ powders synthesized by high temperature solid state method exhibited perovskite based cubic crystal structure, and the average particle size of this powders is about 6μm. By optimizing the calcination process, the BaZr0.9Y0.1O3-δ powders were determined to be calcined at 1200℃, and the calcinations times used were 10 hours. All calcinations were done in laboratory air. The green body was prepared by high-pressure molding and slip casting molding respectively. In high-pressure molding process, two groups of contrast experiments were designed to investigate the impact of binder on green body. One group of BaZr0.9Y0.1O3-δ powder did not add any binder, while another group added polyvinyl alcohol as a binder. Subsequently, two groups of BaZr0.9Y0.1O3-δ powder were embedded in the pressure transmission sample holder made by cubic pyrophyllite , and a thin layer of copper was set between the sample and pyrophyllite to prevent interdiffusion, then put the assembled samples into JL-3600t cubic anvil high pressure apparatus and pressing molding in 1~3GPa. The key of slip casting molding is mold formulation and slurry preparation. In this thesis, we used high-quality gypsum powder to fabricate plaster molds, which have good water absorption and enablesslurry to rapid dehydration molding. Slurry preparation chose an appropriate of particle sized BaZr0.9Y0.1O3-δ powder, added Arabia gum as a binder, appended adequate amount of water and absolute ethyl alcohol, then a superior performance of slurry was obtained after the ball-milling and degassing process. Pouring prepared slurry into plaster molds, and a green body was obtained after drying and mold unloading. BaZr0.9Y0.1O3-δ Ceramics were sintered at high temperatures and atmospheric pressure. For this green body which has been added binder during the molding process, a binder removal technology was designed in the initial stage of sintering process. Heating rate in the decomposition temperature range of binder was as low as possible, and a holding time was set to make sure the binder added can be decompose and overflow completely. After the binder removal process, heating to 1500℃ and holding 10 hours, and then the BaZr0.9Y0.1O3-δ ceramics were prepared. The physical properties and microstructure of BaZr0.9Y0.1O3-δ ceramics were also analyzed in this thesis. |
修改评论