热氧化多孔硅制备及其干涉特性研究

采用电化学阳极氧化法制备彩色薄层多孔硅,经高温热氧化处理后形成稳定的热氧化多孔硅.研究电化学制备条件对热氧化多孔硅的干涉效应和光学厚度的影响,分析热氧化处理前后多孔硅的稳定性.结果表明,在可见光波长范围内,所制备的热氧化多孔硅反射光谱出现一定规律性的干涉条纹,表现出明显的反射干涉现象;随阳极氧化时间、电流密度和HF浓度增大,热氧化多孔硅光学厚度呈增大趋势,当阳极氧化时间为30s、电流密度为520mA/cm2、v(HF):v(C2H5OH)为2:1～5:2时,制备的热氧化多孔硅干涉条纹均匀且光学厚度较大;热氧化处理后,多孔硅结构中的Si-Hx键被Si-O键所取代,其反射干涉特性非常稳定.     

近规整多孔硅电化学制备与表征

电化学阳极氧化条件对多孔硅孔排列的规整度有着显著的影响.提出了一种不需阳极氧化铝模板或预图案化而直接制备近规整多孔硅的电化学方法,分析了氧化时间、电解液组成、HF浓度对多孔硅形态的影响.结果表明,随着阳极氧化时间的增加,多孔硅孔的深度逐渐加大,孔径则呈先增大后稳定的趋势.当氢氟酸(40%)与N-N-二甲基甲酰胺(DMF...     

电化学阳极氧化条件对多孔硅及其光催化性能的影响研究

在HF/乙醇电解液中,采用恒电压电化学阳极氧化法,将P型硅片制备成了多孔硅催化剂。以甲基橙模拟废水为目标物,分析了电化学阳极氧化条件对多孔硅光催化甲基橙脱色率的影响。结果表明:随着HF浓度、阳极氧化时间、电流密度和光照时间的增加,甲基橙的脱色率逐渐增大。当V(HF)∶V(乙醇)=1∶1、阳极氧化时间为30min、电流密度为10mA/cm2以及光照时间为60min时,对甲基橙废水的脱色率较好。用十二烷基苯磺酸钠修饰的多孔硅对甲基橙废水有更高的脱色率。同直接催化相比,光催化甲基橙废水的脱色率提高到45.32%。同时对多孔硅表面形貌进行了表征。     

用脉冲电化学法在低HF浓度下制备多孔硅的研究

用脉冲电化学阳极氧化的方法在5％的低HF浓度下获得多孔硅。多孔硅的形成和脉冲电场的施加、去除过程中与电解液－硅半导体体系中物理化学过程的变化有关。在施加电场的间隙，由于Si／电解液界面处HF的补充，SiO2的溶解增强，使得在低HF浓度下Si的溶解速率比其氧化速率高，从而导致多孔硅的形成。同时，在高电场作用下，由于产生了高浓度的空穴，使得氧化层变厚，导致在低HF浓度或大电流密度下多孔硅的平均孔径增大。     

阳极氧化电流密度和时间对多孔硅形貌和电子发射特性的影响

为了应用于场发射显示器,采用电化学阳极氧化,快速热氧化和磁控溅射等方法制备出了金属/多孔硅/硅基底/金属结构的多孔硅电子发射体,并运用扫描电子显微镜观察了多孔硅的微观形貌,结果发现多孔硅的孔径随着电化学阳极氧化电流密度的增加而增加,多孔硅层的厚度随着阳极氧化电流密度和时间乘积的增加而增加。在真空系统中测量了多孔硅的电子发射特性,电子发射的阈值电压Vth随着多孔硅层厚度的增加而增加;最大的发射效率η为7.5‰,此效率出现在孔径6~16 nm,多孔硅层厚度为11.06μm的样品中,对应的器件电压Vps为30V。     

铝阳极氧化膜纳米孔阵列的微细结构

用电化学阳极氧化法制备了纳米多孔铝阳极氧化膜(AAO模板).采用原子力显微镜(AFM)测试AAO膜,研究了纳米孔阵列的形成机制.结果表明,在AAO膜的表面,除存在六方形的纳米孔阵列外,在孔端还存在六个微小的隆起,相邻的隆起之间彼此相连,看上去酷似一朵盛开的梅花,花的中心就是六方形纳米孔.二维AFM图像显示,以往用扫描电镜表征的纳米孔阵列,实际上是一幅排列整齐、并呈周期性变化的梅花阵列图案.膜背面阻挡层的AFM二维图像表明,膜胞呈六方形,且排列高度有序.膜胞密度为4.3×109/cm2,与孔密度基本一致.阻挡层的三维照片显示,膜胞的底部存在半球状突起,也呈现出规整的阵列图案.     

阳极氧化法制备TiO2纳米管的pH值参数研究

采用电化学阳极氧化法在HF水溶液体系中对钛金属进行表面处理,得到高度规整的TiO2纳米管阵列.主要研究了电解液pH值大小对TiO2纳米管阵列形貌(管径及管长)的影响;用扫描电子显微镜(SEM)对其表面形貌进行表征.结果表明:酸性条件下能形成TiO2纳米管;强碱性环境不利于TiO2纳米管的制备;在可制备TiO2纳米管的pH值范围内,管径和管长随pH值升高而减小.采用微孔模型对pH值的影响机理进行了阐述.     

阳极氧化法制备TiO_2和Al_2O_3有序多孔阵列

采用阳极氧化法制备了TiO2和Al2O3有序多孔阵列,并通过X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、莱茨光学显微镜对制备的TiO2和Al2O3有序多孔阵列进行表征。结果表明,随着氧化电压的增大,TiO2和Al2O3纳米孔的直径增加,孔密度减小。随着氧化时间的延长,TiO2和Al2O3多孔膜厚度增加,到一定时间后膜厚不变。同时讨论了阳极氧化机理,无论是制备TiO2还是Al2O3有序多孔阵列,阳极氧化过程主要由3个阶段组成:阻挡层的形成、阻挡层的溶解、多孔层的稳定生长。     

Ti6A14V表面纳米多孔氧化膜的电解制备及形成机理研究

在(NH4)2SO4/NH4F电解液中,采用阶段升压至预定电压,然后恒压阳极氧化在Ti6A14V表面制备出纳米多孔氧化膜.利用SEM、XRD对纳米多孔氧化膜进行表征.研究表明,电解液pH值和外加电压对纳米多孔氧化膜形成和形貌影响非常大.电解液的pH值=4.O,恒压为20V时,形成孔均匀规整的纳米多孔氧化膜,孔内径约为85nm.纳米多孔氧化膜形成机理是:首先钛合金表面钝化,在F-作用下钝化表面发生孔蚀而形成原始胚胎孔,然后胚胎孔处氧化膜在电场支持下发生场致溶解而成大孔.     

Al-Li合金阳极氧化膜的制备与性能

Al-Li合金在潮湿和盐雾环境中易发生晶间腐蚀、剥落腐蚀和应力腐蚀等形式的破坏。为了提高Al-Li合金的耐蚀性,采用阳极氧化的方法,在15%硫酸溶液中在Al-Li合金表面制备了一层Al_2O_3阳极氧化膜,通过测厚仪及显微硬度计测试了膜层厚度及硬度,通过扫描电镜、电化学测试和腐蚀试验等方法,研究了电流密度、氧化时间等对阳极氧化膜耐蚀性的影响。结果显示:所得氧化膜表面呈多孔状结构,厚度在3~13μm之间,硬度在80~200 HV之间;当电流密度为2.0 A/dm~2、氧化时间为60 min、沸水封孔处理20 min时制备的阳极氧化膜耐蚀性最优。     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to     

Win-Win Cooperation

正The Chinese Premier Li Keqiang's recent trip to the UK has reinforced the China-UK comprehensive strategic partnership;just as the British Prime Minister David Cameron put it,"the relationship is gaining in strength,depth and understanding"after a bucket of business deals being inked worth more than 30 billion US dollars.From the first agreement signing in 2004 to the new agreement of mutual standards recognition and adoption in     

Systematic Approach for Emerging Industry

正A national directory of standards complexes for strategic emerging sectors was recently developed and released jointly by 12governmental departments,namely,SAC,NDRC,MOST,MIIT,MEP,MOA,AQSIQ,State Forest Administration,State Administration of Science and Technology for National Defense,State Oceanic Administration and National Railway Administration.     

Strictest Pollutants Emission Standards

正Four new national standards on air pollutant emission control offi cially issued by the Ministry of Environment Protection(MEP)together with AQSIQ and SAC has been brought into force from July 1,2014.The Emission standard for air pollutants of coal-burning,oil-burning and gasfi red boilers,which is the strictest emission standard historically,will tackle the stubborn pollution problem of boilers and waste incineration in most of China’s regions.     

Instructions to Authors

New Carbon Materials is a bimonthly journal published with the permission of the Ministry of Science and Technology and of the State News and Publication Agency.The journal is sponsored by the Institute of Coal Chemistry,Chinese Academy of Sciences,and is published by Science Press.Aims and Scope     

Progress on Standards Copyright Protection

正Recently,National Copyright Administration of China(NCAC)has rewarded 215 organizations and 179 individuals for their outstanding efforts on investigating standards copyright infringement and piracy in 2013.Hua Jianhua,the Deputy-Director of National Standards Copyright Protection Workgroup Office won a third prize of the national individual award.In 2012,SAC set up the national standards copyright protection working group,and developed policies to crack down standards infringement and piracy behaviors and to strengthen standards copyright protection.