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Isothermal and cyclic oxidation behaviors of chromium samples with and without nanometric CeO2 coating were studied at 900℃ in air. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution electron microscopy (HREM) were used to examine the morphology and microstructure of the oxide film. It was found that ceria coating greatly improved the oxidation resistance of Cr both in isothermal and cyclic oxidizing experiments. Acoustic emission (AE) technique was used in situ to monitor the cracking and spalling of oxide film, and AE signals were analyzed in time-domain and number-domain according to related oxide fracture model. Laser Raman spectrometer was also used to study the stress of oxide film formed on Cr with and without ceria. The improvement in oxidation resistance of chromium is believed mainly due to that ceria greatly reduced the growth speed and grain size of Cr2O3. This fine grained Cr2O3 oxide film might have better high temperature plasticity and could relieve parts of the compressive stress by means of creeping and maintained ridge character and relatively lower level of internal stress. Meanwhile, ceria application reduced the size and number of interfacial defects, remarkably enhanced the adhesive property of Cr2O3 oxide scale formed on Cr substrate. 相似文献
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针对催化制备碳酸甘油酯过程中催化剂易失活、难回收的问题,以Na2Si O3·9H2O为原料,经焙烧、研磨、过筛等工艺处理后,制备得到了易分离且可循环使用的固体碱催化剂,并用于催化甘油与碳酸二甲酯的酯交换反应.探讨了催化剂的粒度和煅烧时间对催化剂活性的影响,以及甘油与碳酸二甲酯的摩尔比、催化剂用量、反应时间等反应条件对酯交换反应的影响.结果表明,当催化剂用量为反应物质量的5%且甘油与碳酸二甲酯的摩尔比为1∶4时,在75℃反应2.5 h后甘油转化率高达97.8%,碳酸甘油酯收率为95.5%. 相似文献
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合成了由吡啶、N-甲基咪唑、N-甲基-2-吡咯烷酮提供有机阳离子, 磷钨酸、对甲苯磺酸提供阴离子的6种离子液体。使用NMR、FT-IR和TG对离子液体表征, 并考察它们催化甘油与月桂酸酯化的催化效果。结果表明, 这些离子液体都具有较好的热稳定性, 以1-(丁基-4-磺酸基)-3-甲基咪唑磷钨酸盐离子液体的热稳定性最好。在最佳条件使用离子液体催化甘油与月桂酸反应时, 阴离子的种类对月桂酸的转化率影响较大, 以对甲苯磺酸为阴离子的离子液体催化反应时, 月桂酸转化率较以磷钨酸为阴离子的离子液体的高;1-(丁基-4-磺酸基)-3-甲基咪唑对甲苯磺酸盐离子液体做催化剂时甘油单月桂酸酯的产率最高。催化剂重复使用性方面, 离子液体重复使用5次催化活性没有明显变化。 相似文献
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Oxidization mechanism in CaO-FeOx-SiO2 slag with high iron content was investigated by blowing oxygen into molten slag so as to oxidize Fe( Ⅱ). The relationship between Fe( Ⅱ ) content and oxidizing time at different temperatures was obtained by chemical analysis. Microstructure of slag was observed by metallographic microscope and SEM. Phases compositions were ascertained by EDXS and XRD. Grain size and crystallizing quantity of magnetite(Fe3O4 ) were determined by image analyzer. The oxidizing kinetic equations were deduced. Confirmed by graphical construction method, Fe( Ⅱ ) oxidizing reaction in CaO-FeOx-SiO2 slag system is of first order, and the reaction apparent energy Eo is 296. 67 kJ/mol in the pure oxygen and 340. 30 kJ/mol in air. The enrichment and crystal growth mechanism of magnetite(Fe3O4 ) phases were investigated. In oxidizing process, content of fayalite declines, while that of magnetite(Fe3O4 ) increases, and iron resources enrich into magnetite(Fe3O4 ) phase. All these provide a theoretical base for compressive utilizing of those slags. 相似文献
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在硫酸镍体系中,pH值为4.5、5.5和6.5的情况下分别制备出3种镍-磷化学镀层,目的在于研究pH值变化对镀层微观结构、内应力水平及热稳定性的影响。采用激光弯曲(LC)应力测量方法对3种镍-磷镀层的应力值进行测量;用电感耦合等离子质谱(ICPM)测量镀层中的磷含量;用扫描电镜(SEM)和配备能量散射谱的透射电镜(TEM/EDS)对镀层的表面形貌及内部相结构进行观测;用差热分析仪(DSC)对镍-磷镀层在高温下的相变规律及热稳定性进行研究。结果表明,pH值为4.5和6.5时制备的镍-磷镀层分别为完整的非晶态和纳米晶结构;pH值为5.5时制备的镍-磷镀层为部分非晶态与纳米晶的混合结构,并且该镀层具有介于前两种镀层之间的P含量及内应力水平。pH值为5.5时制备的镍-磷镀层在经历250℃热处理时发生明显的开裂,TEM测试表明微裂纹起源于Ni/Ni-P相界面;而pH值为4.5和6.5时镍-磷镀层所表现出的高热稳定性分别在于前者更低的拉应力水平及后者的充分的纳米晶结构。pH值为6.5时制备的镍-磷镀层虽然有最高的拉应力值,但其内部充分细小的纳米晶结构会有效避免局部应力集中的发生。此外镀层中可能存在的“反Hall-Petch效应”也是其耐热性能好的原因之一。 相似文献
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鲐鱼加工新产品的研制和生产 总被引:1,自引:0,他引:1
鲐鱼,鲭科,俗称青鲇鱼,生长快、产量高,我国沿海的鲐鱼资源十分丰富。由于汛期集中,保鲜、加工、销售都存在困难。若不深度加工,不仅企业经济效益不高,更重要的是不能很好地利用海洋资源。本公司自90年起重点开发鲐鱼产品,曾研制出液熏的片软罐头。营养鱼松等产品;最近二年又研制出低盐鲐鱼干和味淋鲭片两个新产品,现探讨其生产工艺和经济效益。1低盐鲐鱼干低盐鲐鱼干水份含量高,盐分含量低,系日本静冈县首创。据考伊豆市和沼津市在大正年间就已开始生产。近来,已扩大到参鱼、沙丁鱼、秋刀鱼等鱼类。1.1材料与方法原料:本公司12月份捕捞较肥满的鲐鱼,条重为2009左右的冰鲜鱼。抗氧化剂:杭州东亚茶多酚天然抗氧化剂。 相似文献
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张林楠 《水电自动化与大坝监测》1981,(4)
为了测量坝体混凝土荷载及静水压力引起坝基的不均匀沉陷所产生的坝体垂直于坝轴线平面上的转动变化,东北地区已建成的电站多数采用水管式倾斜仪或几何水准(精密水准)测量方法进行观测。通过多年的实践证明,水管式倾斜仪操作简便,需要人员少,但在漫长 相似文献