Interface engineering of nanoceramic hematite photoelectrode for solar energy conversion

This work addresses the role of different modifiers on the overall photocurrent response, which allowed a dual material insertion, increasing the charge separation without compromise the surface catalysis. Sn-addition onto nanoceramic hematite photoelectrodes clearly increased flat band potential, promoting a good charge separation, and shifting the onset to a higher potential, attributed to the surface-trapping state created by this modification. Notoriously, Sn-hematite photoelectrodes loaded with NiFeO_x exhibited the highest photocurrent density, suggesting a partially recovered surface-trapping states created during the electrode designing. The well-known cocatalyst acted in the overall photoelectrocatalytic response with no significant effect on the turn-on voltage, in other words, with minor effect related to catalytic efficiency. The dual modification contributes to understand the role of different modifiers allowing to satisfactorily improve charge separation while maintaining the conductivity attributed to IV-group ions.     

氮化硅/碳化硅纳米陶瓷的显微组织与抗弯性能

研究了氮化硅／碳化硅纳米复合陶瓷经三点弯曲试验后的显微组织和断口形貌。结果表明，随着SiC纳米粉含量的增加，断口从沿晶断裂向穿晶断裂过渡；当SiC的质量分数是15％时，复合陶瓷的显微组织明显细化，抗弯强度、断裂韧度明显提高。     

Synthesis of nickel aluminate nanoceramic compound from aluminum and nickel carbonate by mechanical alloying with subsequent annealing

The aim of present work was to produce pure nickel aluminate (NiAl₂O₄) nanoceramic compound by high energy milling of nickel carbonate (NiCO₃) and aluminum (Al) powders followed by annealing. Phase composition, thermal behavior, morphology and microstructure of powder samples were characterized by means of X-ray diffraction, differential scanning calorimeter, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The results showed that formation of NiAl₂O₄ spinel compound from NiCO₃ and Al powders took place in three steps: oxidation of Al to Al₂O₃, decomposition of NiCO₃ to NiO and CO₂, and finally the solid state reaction between Al₂O₃ and NiO. It was also demonstrated that single phase NiAl₂O₄ spinel compound can be produced by 5 h of mechanical milling with subsequent annealing of NiCO₃/Al mixture at 900 °C for 2 h, which is ∼500 °C lower than the temperatures used in the traditional solid state methods. The particle diameter of the produced NiAl₂O₄ spinel compound was found to be less than 100 nm as measured by transmission electron microscopy.     

Problems in making a dense nanoceramic

The classification of nanomaterials is proposed. Problems are considered in making nanoceramics from nanopowders of various grain sizes: nanopowder preparation, the manufacture of molding materials, molding blanks, and sintering them. There is a brief discussion of ways of making ceramic nanocomposites in the decomposition of unstable solid phases and the use of nanodimensional particles. Template methods are discussed for making ceramic nanocomposites. Translated from Novye Ogneupory, No. 4, pp. 109 – 115, April, 2009.     

氮化硅纳米复合陶瓷的抗氧化性与耐蚀性研究

采用极性分散剂和超声分散技术，在氮化硅微米粉中加入碳化硅纳米粉真空热压制备出氮化硅／碳化硅（n)纳米复合陶瓷，研究了纳米增强相对纳米复合陶瓷抗氧化性与耐蚀性的影响。结果表明：随着SiC纳米粉的含量的增加，纳米复合陶瓷在空气中加热时抗氧化性增强，其中含15％SiC纳米粉的纳米复合陶瓷抗氧化性最好；纳米复合陶瓷的耐碱性也非常好，适于在酸、碱性环境中使用。     

The effect of solution temperature and pH on corrosion performance and morphology of nanoceramic‐based conversion thin film

In the present study, a nanoceramic hexafluorozirconic acid was used as an eco‐friendly conversion coating, which is free of the conventional phosphate salts. The effect of practical parameters on morphology and corrosion resistance of the coating was studied. Anti‐corrosion behavior of the nanoceramic‐based conversion coating on cold rolled steel substrates was evaluated at different solution pH and temperatures, utilizing the electrochemical impedance spectroscopy and direct current polarization. Moreover, the morphology of thin films was studied using field emission scanning electron microscopy (FE‐SEM). The results revealed that the conversion thin films formed at a dipping temperature of 20 °C and pH 4.5 showed best anti‐corrosion performance. SEM images indicated that increasing solution temperature resulted in micro‐cracks creation and lack of consistency on the surface of the conversion coating. Moreover, the morphological structure changed with increasing pH value.     

纳米介电陶瓷的晶粒尺寸效应及低温烧结技术

微电子技术对纳米陶瓷材料的需求催生了各种新型纳米陶瓷材料制备与烧结技术的开发与研究。结合纳米晶介电陶瓷的晶粒尺寸效应（即晶粒尺寸与陶瓷介电特性、烧结特性之间的依赖关系）,系统介绍了制备纳米晶介电陶瓷材料的低温烧结技术,包括液相烧结、两步烧结、水热压烧结和放电等离子体烧结,重点阐述了各种低温烧结技术的基本原理、使用设备、实验参数,比较了其优、缺点和应用领域,综述了近年来国内外相关领域的研究进展,并对这些技术目前存在的问题和今后的研究方向进行了分析和展望。     

锆钛酸铅纳米陶瓷粉体的水热合成技术

阐述了水热合成法制备锆钛酸铅纳米陶瓷粉多晶体的原理、工艺过程及其特点,重点分析了水热法制备锆钛酸铅纳米陶瓷粉多晶体的溶解/沉淀和原位合成两种形成机制,以及工艺过程中的影响因素,如反应的温度、碱度、时间、粉体的洗涤、干燥等影响因素。通过分析得出水热法制备锆钛酸铅纳米陶瓷粉多晶体适宜的工艺参数为:反应温度150～220℃,碱度pH7～11.5,反应时间2～4h,采用冷冻干燥法可获得分散性好、粒度均匀的锆钛酸铅纳米粉体。     

铁电纳米材料的制备、性能和应用前景

对近年来有关铁电纳米粉体、纳米复合材料、以及纳米陶瓷的制备,结构和性能进行了介绍.对由于粒子尺寸减小引起的结构和性能的改变及其相关机理进行了讨论.透明铁电纳米复合材料可望在光学存储、光学计算等光学器件中得到应用.而纳米陶瓷由于介电特性、耐电压、抗老化、机械强度等性能的提高,因而可以广泛用于改进现有电容器材料的性能,获得性能更加优良的器件.     

火焰喷涂制备纳米陶瓷超润滑涂层及其防污性能

仿猪笼草结构的灌注液体型超润滑涂层(SLIPS)因具有优异的自清洁防污性能备受关注,但目前存在制备工艺复杂、成本较高、不适宜大规模制备等问题,影响了该技术的实际应用。针对这一问题,利用火焰喷涂技术制备SLIPS表面的技术工艺,成功在不锈钢表面制备了基于纳米二氧化钛的SLIPS涂层,并研究了涂层结构及性能。利用SEM分析了涂层的表面形貌和微观结构;利用接触角测量仪研究了涂层的浸润性能;通过藻类贴附试验评价了涂层的防污性能。结果表明：所制备涂层表面接触角达到118.01°,滚动角达到4.54°,呈超润滑性能,对海洋小球藻附着率降低了98.56%。文中研究为制备低成本、大规模SLIPS涂层提供了一种可行的思路。