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Synthesis of GdF_3 from the Gd_2O_3-NH_4HF_2 system

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Rare Metals 2007年第5期26卷 482-487页

作者： HAO Zhanzhong ZHANG Jianliang WANG Bin ZHANG xidong Metallurgical and Ecological Engineering School University of Science and Technology Beijing Beijing 100083 China Baotou Teachers College Baotou 014030 China

GdF3 was synthesized with Gd2O3 and NH4HF2 under atmospheric pressure and vacuum. The effects of pressure,temperature,and reactant ratio on the reaction process were investigated. A new mechanism for the synthesis of GdF3 was proposed. Powdered Gd2O3 started to react with NH4HF2 at low temperature,and the products were GdNH4F4,NH4F,NH3,and H2O. GdNH4F4 decomposed to GdF3 and NH4F after further high-temperature treatment,accompanying the volatilization and decomposition of NH4F. The whole process could be divided into three steps： synthesis,decomposition,and deamination. The initial and final reaction temperatures decreased under vacuum condition. An optimized process for the preparation of GdF3 was obtained： synthesis under atmospheric pressure at low temperature and decomposition and deamination under vacuum at high temperature.

关键词： inorganic chemistry Gd NH4HF2 synthesis

K439B镍基铸造高温合金800℃长期时效过程中碳化物的演变规律

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材料导报 2024年第15期38卷 8-12页

作者：高磊屈星海吴一栋陈晶阳肖程波惠希东北京科技大学新金属材料国家重点实验室北京100083 中国航发北京航空材料研究院先进高温结构材料重点实验室北京100095

K439B镍基合金是一种承温能力达800℃的新型铸造高温材料,在发动机机匣类复杂结构件有重要应用前景。作为该合金中的主要晶界强化相,碳化物在合金长期时效过程中的演化规律尚不清楚。以K439B合金为对象,在800℃下对该合金进行了6000~100... 详细信息

K439B镍基合金是一种承温能力达800℃的新型铸造高温材料,在发动机机匣类复杂结构件有重要应用前景。作为该合金中的主要晶界强化相,碳化物在合金长期时效过程中的演化规律尚不清楚。以K439B合金为对象,在800℃下对该合金进行了6000~10000 h的等温时效实验,研究了其长期时效过程中碳化物的演变规律和转变机理。结果表明,K439B合金的组织稳定性优异。经过长期时效后,晶界和枝晶间组织中仍保留大部分标准热处理态时的MC型碳化物,仅有部分MC型碳化物分解为M_(23)C_(6)型碳化物和γ′相,未出现η相和σ相等TCP有害相。晶界M_(23)C_(6)型碳化物表现出两种不同的粗化行为,一是M_(23)C_(6)型碳化物逐渐宽化,在长期时效后宽度均一,碳化物排列整齐;二是在某些晶界部位,粗化后的M_(23)C_(6)型碳化物呈现不规则的形状,甚至向晶粒内部延伸。晶界M_(23)C_(6)型碳化物并未出现沿整个晶界的完全相连情况,其主要是γ′相颗粒将两个相邻的M_(23)C_(6)型碳化物分隔所致。

关键词： K439B镍基高温合金长期时效组织稳定性碳化物

A Regional Ocean Reanalysis System for Coastal Waters of China and Adjacent Seas

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Advances in Atmospheric Sciences 2011年第3期28卷 682-690页

作者： Guijun Han Wei Li Xuefeng Zhang Dong Li Zhongjie he xidong Wang Xinrong Wu Ting Yu Jirui Ma State Ocean Adm Natl Marine Data & Informat Serv Key Lab Marine Environm Informat Technol Tianjin 300171 Peoples R China

A regional ocean reanalysis system for the coastal waters of China and adjacent seas has been developed by the National Marine Data and Information Service（NMDIS）.It produces a dataset package called CORA （China ocean reanalysis）.The regional ocean model used is based on the Princeton Ocean Model with a generalized coordinate system（POMgcs）.The model is parallelized by NMDIS with the addition of the wave breaking and tidal mixing processes into model *** assimilation is a sequential three-dimensional variational（3D-Var） scheme implemented within a multigrid *** include satellite remote sensing sea surface temperature（SST）,altimetry sea level anomaly（SLA）,and temperature/salinity *** reanalysis fields of sea surface height,temperature,salinity,and currents begin with January 1986 and are currently updated every year. Error statistics and error distributions of temperature,salinity and currents are presented as a primary evaluation of the reanalysis fields using sea level data from tidal gauges,temperature profiles,as well as the trajectories of Argo *** case studies offer the opportunity to verify the evolution of certain local *** evaluations show that the reanalysis data produced provide a good representation of the ocean processes and phenomena in the coastal waters of China and adjacent seas.

关键词： ocean reanalysis data coastal waters China adjacent seas sea temperature salinity currents ocean circulation

Incremental 4D-VAR assimilation scheme based on Lorenz model

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Acta Oceanologica Sinica 2008年第z1期27卷 93-100页

作者： WANG xidong XU Dongfeng XU Xiaohua State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administra-tion Hangzhou 310012China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administra-tion Hangzhou 310012China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administra-tion Hangzhou 310012China

Four-dimensional variational(4D-VAR) data assimilation method is a perfect data assimilation solution in theory, but the computational issue is quite difficult in operational *** incremental 4D-VAR assimilation scheme is set up in order to reduce the computational cost. It is shown that the accuracy of the observations, the length of the assimilation window and the choice of the first guess have an important influence on the assimilation outcome through the contrast experiment. Compared with the standard 4D-VAR assimilation scheme, the incremental 4D-VAR assimilation scheme shows its advantage in the computation speed through an assimilation experiment.

关键词： 4D-VAR assimilation,incremental 4D-VAR assimilation Lorenz model

Hydrothermal growth of well-aligned TiO_2 nanorod arrays: Dependence of morphology upon hydrothermal reaction conditions

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Rare Metals 2010年第3期29卷 286-291页

作者： LI Yuxiang ZHANG Mei GUO Min WANG xidong Department of Physical Chemistry University of Science and Technology Beijing Beijing 100083 China College of Engineering Peking University Beijing 100871 China

Well-aligned TiO2 nanorod arrays （TNAs） were prepared on pretreated quartz substrates via hydrothermal *** effect of the different preparation conditions on the growth morphologies of TNAs was systematically investigated by X-ray diffraction （XRD） and field-emission scanning electron microscopy （FE-SEM）.The photocatalytic properties were tested by photodegradation of a methyl blue *** is demonstrated that the hydrothermal reaction conditions,such as precursor concentration,hydrothermal reaction temperature,and hydrothermal reaction times,can greatly affect the growth of *** the preparation process,TNAs with 2 μm in length and 140-170 nm in diameter and well-aligned orientation have been successfully *** photocatalytic experiment results indicate that TNAs have much better photocatalytic activity than TiO2 nanoparticles.

关键词： titanium dioxide nanorod arrays hydrothermal method photocatalyst

Three-dimensional flexible Au nanoparticles-decorated TiO_(2) nanotube arrays for photoelectrochemical biosensing

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Journal of Materials Science & Technology 2020年第21期56卷 162-169页

作者： xidong Zhang Dong Yue Ling Zhang Shiwei Lin State Key Laboratory of Marine Resource Utilization in South China Sea School of Materials Science and EngineeringHainan UniversityHaikou 570228China

Controlling the charge transfer and thus enhancing the excitons’lifetime are the key to the realization of efficient photoelectrochemical(PEC)***,fabrication of flexible and collapsible sensors can greatly facilitate the implementation of smart PEC sensing devices into practical ***,we sagely designed and successfully fabricated three-dimensional flexible Au nanoparticles-decorated TiO_(2) nanotube arrays(Au@TiO2)for the efficient PEC biosensing of *** Schottky barrier derived from the Au@TiO2 heterostructure efficiently separates the charge carriers at the junction interfaces,thus greatly increasing the concentration and lifetime of holes left in the valence band of *** separated holes further evidently generate the active hydroxyl radicals,which can specifically recognize and oxidize *** a result,Au@TiO_(2) exhibits excellent photoelectric activity and selectivity,far superior to TiO_(2) without decorated Au *** addition,such asymmetric Au@TiO_(2) system has been proved to feature the intrinsic flexibility nature,since its PEC biosensing performance is almost unaffected under indirect light irradiation and serious tensile strain.

关键词： Photoelectrochemical biosensing Metal/semiconductor interface Flexibility TiO_(2)nanotube arrays

Puncture Phenomena and Mechanism Analysis of a RTV Coated Cap and Pin Insulators in a Steep-front Impulse Voltage Test

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CSEE Journal of Power and Energy Systems 2021年第4期7卷 832-839页

作者： Tao Deng xidong Liang Zhiyi Su Jun Zhou Electrical Engineering Department Tsinghua UniversityBeijing 100084Chinaand also with Department of High VoltageChina Electric Power Research Institute Co.LtdBeijing 100192China Department Tsinghua UniversityBeijing 100084China Department of High Voltage China Electric Power Research Institute Co.LtdBeijing 100192China

In recent years,more than 6 million room temperature vulcanized(RTV)silicone rubber coated cap and pin insulators with high mechanical ratings were used in ultra-high voltage transmission lines in China to improve pollution ***,the unexpected puncture phenomena of RTV coated insulators were exposed during steep-front impulse voltage tests;for instance,the steep-front impulse voltage test pass rate decreased to less than 50% for 550 kN glass insulators with RTV *** steep-front impulse voltage test is the most effective method used to check the insulation quality of cap and pin insulators・This unexpected phenomenon once caused serious concerns to power *** this paper,several possible factors that affect the puncture of insulators were ***,the extent of the decline in the breakdown of the 550 kN glass cap and pin insulators with and without RTV coatings were *** initial puncture location was then found,and the developmental process of the arc on the insulator surface in steep-front impulse voltage tests was observed with an ultra-high-speed intensified charge coupled device ***,a breakdown mechanism is *** puncture phenomena of a RTV coated insulator in a steep-front impulse voltage test is essentially an electrical breakdown of the internal insulation・The RTV coating induces the close adherence of the arc to the surface of the *** closeness changes the arc development path on the insulator surface and facilitates easy breakdown in the shed weak *** these factors result in a significant increase in the breakdown probability of RTV coated insulators in steepfront impulse voltage tests.

关键词： Cap and pin insulator puncture RTV coating steep-front impulse voltage test

一种兼具装饰性和耐蚀性的镁合金红色微弧氧化膜层的制备

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电镀与涂饰 2024年第2期43卷 37-44页

作者：马焕祥林国峰徐曦东王苗王文博宁波旭升集团股份有限公司浙江宁波315806 北京航空航天大学宁波创新研究院浙江宁波315800

[目的]镁合金微弧氧化在装饰性方面的研究报道不多。[方法]采用微弧氧化技术在ZM5镁合金表面制备了红色的微弧氧化陶瓷层,研究了主盐Na2SiO3和着色剂CuSO_(4)的质量浓度,配位剂的种类,以及氧化时间对膜层的影响。[结果]在含有Na2SiO320.... 详细信息

[目的]镁合金微弧氧化在装饰性方面的研究报道不多。[方法]采用微弧氧化技术在ZM5镁合金表面制备了红色的微弧氧化陶瓷层,研究了主盐Na2SiO3和着色剂CuSO_(4)的质量浓度,配位剂的种类,以及氧化时间对膜层的影响。[结果]在含有Na2SiO320.0g/L、CuSO_(4)0.5g/L、乙二胺四乙酸二钠0.5g/L和NaF 0.5g/L的电解液中,以电流密度3.5A/dm^(2)氧化25min,能够获得厚度约为31.4μm的红色微弧氧化膜。该膜层致密,主要由MgO、Mg_(2)SiO_(4)和CuO组成,在铜加速乙酸盐雾试验中出现锈蚀的时间为48h。[结论]ZM5镁合金表面红色微弧氧化膜的耐腐蚀性能比在不加CuSO_(4)时所得白色微弧氧化膜更好。

关键词：镁合金微弧氧化红色硫酸铜耐蚀性

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氯盐与硫酸盐复合侵蚀下钢筋混凝土锈裂行为

哈尔滨工业大学学报 2024年第2期56卷 151-160页

作者：俞小彤常西栋周文涛廖迎娣陈达河海大学港口海岸与近海工程学院南京210098 海岸灾害及防护教育部重点实验室(河海大学) 南京210098

为评估海洋、盐湖等环境中钢筋混凝土结构耐久性,通过试验与理论相结合探究氯盐与硫酸盐复合侵蚀下钢筋混凝土锈裂特性。通电腐蚀5%(质量分数)NaCl、5%NaCl+5%Na_(2)SO_(4)溶液中钢筋混凝土试件,对比分析混凝土表观形貌、钢筋锈蚀特征... 详细信息

为评估海洋、盐湖等环境中钢筋混凝土结构耐久性,通过试验与理论相结合探究氯盐与硫酸盐复合侵蚀下钢筋混凝土锈裂特性。通电腐蚀5%(质量分数)NaCl、5%NaCl+5%Na_(2)SO_(4)溶液中钢筋混凝土试件,对比分析混凝土表观形貌、钢筋锈蚀特征。设计伴随的混凝土腐蚀试验,类比保护层腐蚀劣化,分析混凝土力学性能。结果表明:硫酸盐的存在改变胀裂前混凝土形貌,使得单一氯盐侵蚀下的“白须”消失,表面粉化并出现盐结晶,延长胀裂时间;复合侵蚀下钢筋锈蚀率低于单一氯盐侵蚀,二者均显著低于法拉第定律理论值;锈胀裂缝宽度与钢筋锈蚀率线性相关,硫酸盐的存在增大裂缝随钢筋锈蚀发展的速率;通电环境中,受腐蚀混凝土的抗压强度先升高后降低,劈裂抗拉强度不断降低。提出受腐蚀混凝土的抗拉强度演化经验公式。在经典锈胀模型的基础上考虑锈蚀产物对裂缝的填充作用,并将硫酸盐的影响考虑至混凝土抗拉强度、钢筋腐蚀电流密度中,建立复合侵蚀下钢筋混凝土胀裂时间预测模型,并验证了模型的有效性。

关键词：氯盐-硫酸盐侵蚀混凝土腐蚀锈胀力胀裂时间

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