共查询到20条相似文献,搜索用时 78 毫秒
1.
Bi2O3-Y2O3体系中纳米δ-Bi2O3相的生成规律研究 总被引:1,自引:1,他引:0
以分析纯的Bi(NO3)3·5H2O和Y (NO3)3*6H2O作为原料,经反向滴定法化学共沉淀、干燥和430℃焙烧后获得(75mol%Bi2O3+25mol%Y2O3)纳米复合粉体,粉体平均粒度30nm以下;通过常压反应烧结工艺制备了纳米Bi2O3-Y2O3快离子导体,对烧结过程中高导电相(纳米δ-Bi2O3)的形成规律研究结果表明烧结初期以固溶反应为主,后期以晶粒长大为主,晶粒生长规律符合(D-D0)2=K·t抛物线方程;用模式识别技术对δ-Bi2O3相生成的工艺条件进行了优化. 相似文献
2.
3.
用碳铵共沉淀法制备LaAlO3粉体前驱体,1200℃下烧结,可得到性能稳定的LaAlO3粉体。经X射线衍射分析产物为单相,属具有钙钛矿结构的三角晶系,其XRD图谱与JCPDS卡84-0848完全一致。采用库尔特LS-230粒度分析仪对共沉淀法和高温固相法合成的两种粉末样品进行粒度分析,发现共沉淀法合成的样品粒度细且分布均匀。分析了上述两种方法合成的粉末样品的SEM照片,发现共沉淀法不仅能降低合成温度,而且可使生成产物结晶均匀,对细化粉体晶粒也有较大作用。 相似文献
4.
5.
采用湿化学共沉淀法合成了Nd3+掺杂的氧化镥纳米晶粉体,研究了三种不同沉淀剂(NH4OH、NH4HCO3、NH4OH+NH4HCO3)对Nd3+:Lu2O3纳米晶粉体性能的影响.采用NH4OH+NH4HCO3混合溶液作复合沉淀剂所得粉体具有比表面积高(13.37m2/g)、颗粒尺寸小(~30nm)、粒度分布窄(60~160nm)的优点.该粉体经过干压和等静压成型后,素坯从室温至1400℃获得的线性收缩率可达17%,其烧结活性明显高于其它两种沉淀剂所得的粉体.在流动H:气氛下,经1880℃/8h烧结可获得具有优良光学透明性的Nd3+:Lu2O3透明陶瓷,在1080nm波长处的直线透过率超过75%. 相似文献
6.
醇-水溶液加热法制备纳米氧化锆粉体 总被引:11,自引:0,他引:11
本研究采用了一种新颖的粉体制备方法-醇-水溶液加热法来制备纳米ZrO_2(Y_2O_3)粉体.实验结果表明:通过选择适当的条件,该方法可制得粒径小、团聚少的纳米ZrO_2(Y_2O_3)粉体.与通常的共沉淀法相比。该方法制得的粉体因形成一种“包裹”结构,使得单斜相含量随煅烧温度的升高而减少,从而更有利于烧结. 相似文献
7.
纳米Ti0.8Cr0.2OxNy粉体的制备与表征 总被引:1,自引:0,他引:1
以沉淀法制备的纳米TiO2/Cr2O3复合粉体为原料,采用氨解法在800℃、氮化8h制备了纳米Ti0.8Cr0.2OxNy粉体.对纳米TiO2/Cr2O3复合粉体和合成的氧氮化物粉体用俄歇电子能谱(AES)、氮吸附比表面积(BET)、X射线衍射(XRD)、透射电子显微镜(TEM)、电子探针显微分析(EPMA)等方法进行了表征.结果表明:沉淀法可以制备出组成均匀的纳米TiO2/Cr2O3复合粉体,该复合粉体在800℃氮化8h可得到粒度为20~30nm的纯立方相Ti0.8Cr0.2OxNy纳米粉体,其比表面积达46.74m^2/g. 相似文献
8.
9.
10.
共沉淀法制备YAG超细粉及透明陶瓷 总被引:13,自引:1,他引:13
研究了共沉淀法制备YAG透明陶瓷的工艺。采用Al(NO3)3和Y(NO3)3的混合溶液为母盐,以碳酸氢铵为沉淀剂,采用共沉淀法制备了化学组成为Y2(CO3)3·nH2O+NH4AlO(OH)HCO3的碳酸盐先驱沉淀物。使用透射电镜和X射线衍射对先驱沉淀物的形貌及煅烧过程的相转变进行了研究。结果表明先驱沉淀物在900℃煅烧2h后完全转变为YAG相。1100℃煅烧后得到的YAG粉体具有良好的烧结性能。使用0.5%(质量分数)的TEOS(正硅酸乙酯)作为烧结添加剂,1700℃真空烧结5h后,得到了透明YAG烧结体。 相似文献
11.
《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
12.
Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
13.
14.
A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
15.
On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
16.
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. 相似文献
17.
C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
18.
《中国标准化(英文版)》2014,(4)
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 相似文献
19.
《中国标准化(英文版)》2014,(5)
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. 相似文献
20.
《中国标准化(英文版)》2014,(4)
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 相似文献