掺镍对钛酸钡陶瓷结构及介电性能的影响

采用溶胶-凝胶(Sol-gel)法制备均匀掺镍钛酸钡纳米晶粉体及其陶瓷.通过XRD和SEM对掺镍钛酸钡粉体及陶瓷进行表征,并测定陶瓷的介电性能,主要研究掺镍量对钛酸钡陶瓷的相组成、显微组织和介电性能的影响.结果表明:采用Sol-gel法制得掺镍钛酸钡基纳米晶立方相粉体(25nm),经烧结后可得到四方相钛酸钡.氧化镍在钛酸钡陶瓷中的溶解限约为0.9 at.%(约为固相掺杂时的2倍);掺镍量低于此溶解限时,随着掺镍量的增大,陶瓷晶粒的长大趋势受到抑制,陶瓷的居里温度降低;当掺镍量高于此溶解限时,陶瓷晶粒长大,陶瓷的居里温度保持在85℃;随掺镍量的增加,陶瓷最大介电常数εm呈先增大后减小的趋势.     

磷掺杂钛酸钡陶瓷烧结过程及介电性能的研究

本文研究了掺杂微量元素磷对钛酸钡陶瓷烧结过程、结构及介电性能的影响。在湿化学法合成的高纯钛酸钡超细粉中，加入0．4atm％的二异丙基亚磷酸酯（P2O5的质量分数为0．14％），不加粘合剂直接压片成型，于1150－1350℃条件下无压烧结。用SEM，TMA，XRD及低频阻抗分析仪，测试样品的烧结性能、微观形貌、晶体结构和介电性能。结果表明：由于磷的加入，晶粒边界形成BaO-TiO2-P2O5三元系液相烧结，在较长的温度下即形成致密的陶瓷，1200℃保温2h的样品致密度达到理论密度的96％：1150～1200℃烧成的陶瓷，其室温介电常数高达6100－5500；居里温度随烧结温度的降低略有下降。因此，微量磷元素的掺杂有助于改善钛酸钡陶瓷的烧结过程和提高介电性能。     

改进的sol-gel工艺制备细晶Ba0.6Sr0.4TiO3陶瓷及其介电性能的研究

用改进的sol-gel工艺制备了细晶钛酸锶钡(Ba0.6Sr0.4TiO3,BST)陶瓷块体,研究了BST陶瓷的结晶与介电性能.在这种改进sol-gel的工艺中,用传统的固相反应煅烧形成BST粉体,经高能球磨制备BST纳米陶瓷粉体,再将一定质量的纳米粉体加入到相同化学组成的BST的溶胶液中,经普球球磨12h后,制备成悬浮性好,分散均匀的浆料.浆料可用来制备BST陶瓷,并在1200℃保温2h烧结成瓷,结果显示,BST陶瓷块体结构致密,晶粒尺寸在0.15～2μm之间.分析了样品的介电性能和晶粒尺寸对材料介电性能的影响.介电温谱显示,在0℃,100kHz时,相对介电常数为2500,介电损耗为0.02;并且存在明显的弥散相变.     

水热法合成陶瓷LaPO_4的微波介电性能（英文）

通过水热法和固相反应法制备了LaPO4粉体,分别在1030~1340℃和1300~1460℃范围内对粉体进行了烧结,得到了LaPO4陶瓷,研究对比了两种方法得到的陶瓷的烧结行为和微波介电性能。结果表明:和固相法相比,水热法得到的陶瓷由于粉体粒径小更易于烧结,微波介电性能更优;在1260℃条件下烧结2 h得到的水热法陶瓷具有最好的微波介电性能:介电常数为10.2,Q×f值为129704 GHz(f=10.2 GHz),谐振频率温度系数值为–58.6 ppm/℃;水热法陶瓷的Q×f值为固相法的2.47倍,烧结温度比固相法低140℃。     

CuO对钛酸镁基介质陶瓷性能的影响

钛酸镁基陶瓷是一种重要的功能陶瓷.本文采用固相反应法合成了Mg2TiO4粉末,主要研究了CuO对该体系陶瓷介电性能的影响.结果表明:添加CuO明显降低了烧结温度,当添加0.5%CuO时,烧结体介电性能良好,在1360℃烧结2h,烧结体的体积密度达到3.48g/cm3,在10KHz下介电常数达19.07,介电损耗为0.0017.XRD及SEM分析表明:烧结体的主晶相为Mg2TiO4,次晶相为CaTiO3,同时含有少量的MgTiO3,烧结体晶粒发育良好,平均晶粒尺寸为10～20μm.     

钛酸钡陶瓷烧结动力学曲线的研究

以超重力反应沉淀法(HGRP)制备的纳米钛酸钡粉体为原料,以热膨胀仪为测试手段,对钛酸钡陶瓷的烧结动力学曲线特征进行了研究.结果表明,烧结温度和成型坯片密度都会对钛酸钡陶瓷的烧结过程产生影响,所表现出的烧结动力学曲线特征也不相同,而升温速率几乎不对坯片的烧结动力学曲线特征产生影响.随着烧结温度的升高,坯片收缩率增大,当烧结温度由1150℃升到1300℃时,收缩率由6.7%增大到23.2%;坯片的密度增大,收缩率减小,当成型坯片相对密度由61.08%增大到64.42%时,收缩率由17.5%减少到14.4%;升温速率增大,坯片开始收缩的温度及收缩率几乎不变.     

(1-x)(Mg0.9Co0.1)TiO3-x(Ca0.61La0.26)TiO3陶瓷的微波介电性能（英文）

研究了(1-x)(Mg0.9Co0.1)TiO3-x(Ca0.61La0.26)TiO3(MCT-CLT)体系陶瓷的微波介电性能.目的是通过(Ca0.61La0.26)TiO3(CLT)协调(Mg0.9Co0.1)TiO3(MCT)陶瓷的谐振频率温度系数.实验发现,烧结温度和陶瓷组成对微波介电性能影响显著,当烧结温度为1300℃时,可以获得良好的致密度,当烧结温度超过1300℃时,陶瓷致密度和介电性能下降.此外,随着CLT含量的增加,材料的介电常数增大,品质因数减小.当CLT含量为13%,烧结温度为1300℃,保温2h,(MCCLT)陶瓷具有优良微波介电性能,εr=22.4,Q×f=35000 GHz,τf=-8.7×10-6/℃,从而达到实用要求.     

细晶Ba0.6Sr0.4TiO3(BST)陶瓷材料的制备与介电性能

采用改进的Sol-gel工艺和传统烧结技术制备了晶粒尺寸在0.15～10μm的Ba0.6Sr0.4TiO3(BST)陶瓷,观察了样品的显微结构,并对样品的介电性能进行了测试,分析了晶粒尺寸对材料介电性能的影响.实验结果表明:改进的Sol-gel工艺和两步烧结法可以有效地控制Ba0.6Sr0.4TiO3(BST)陶瓷的晶粒尺寸.晶粒尺寸的降低,材料的介电常数也随之下降,介电峰呈现明显的铁电-顺电弥散相变;但当陶瓷的晶粒尺寸＜1 μm,介电常数出现峰值,铁电相变温区变窄.     

纳米钛酸钡粉体的制备和烧结动力学研究

以四氯化钛、八水合氢氧化钡和氨水为原料,首先制备出氢氧化钛凝胶,然后以乙醇为溶剂,采用两步沉淀法在低温常压下合成了立方相纳米钛酸钡粉体.研究了反应温度、反应物浓度和反应时间对粉体物相和粒径的影响,利用XRD和TEM对粉体进行了表征.实验结果表明,在低于80℃的反应温度下可以制备出粒径＜20nm、结晶性能良好且形貌规则的纳米钛酸钡粉体.此外,以合成的粉体为原料,以热膨胀仪为测试手段,对钛酸钡陶瓷的烧结动力学进行了研究.结果表明,陶瓷的烧结温度为1150～1250℃,在1250℃的烧结温度下保温2h,陶瓷坯体的相对密度约93%,室温介电常数约4020.     

烧结方式对共沉淀法制备ZnNb_2O_6陶瓷介电性能的影响

采用化学共沉淀法制备Zn Nb2O6超细粉体,所得的粉体经煅烧压制后通过微波和常规烧结工艺制备Zn Nb2O6陶瓷,并研究两种烧结方法对Zn Nb2O6陶瓷相对密度、物相、表面形貌、介电性能等的影响。结果表明,共沉淀法制得的Zn Nb2O6粉体晶粒细小、均匀,近似棒形,尺寸约为150nm;与常规烧结工艺相比,采用微波烧结工艺可将Zn Nb2O6陶瓷烧结温度降低约150℃,烧结时间缩短1.5 h,进而有效抑制了烧结过程中锌元素的挥发;微波烧结后的Zn Nb2O6陶瓷晶粒粒径约为6μm,排列均匀,且气孔率低;微波烧结可有效改善Zn Nb2O6陶瓷的微波介电性能,与传统烧结方式对比,微波烧结可提高εr和Q×f为4.6%和15.6%左右,τf更趋于正值方向。同时对微波烧结陶瓷介电性能进行了较为系统的理论分析。     

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.