低温共烧MnZn铁氧体的研究现状

MnZn铁氧体在电子工业上有着非常广泛的应用。MnZn铁氧体与银电极的低温共烧是实现其无源集成组件的关键。本文分析了影响MnZn铁氧体低温烧结的各种因素,重点介绍了目前国内外在MnZn铁氧体低温共烧领域中所取得的相关成果,最后提出其未来发展的方向。     

LTCC铁氧体叠层片式器件及材料的国内外发展动态

根据最近(2008.10.10)举行的第十届国际磁铁氧体会议(ICF10)和第十三届全国磁学会议(2008.10.31)资料,以及近两年有关专业会议文献,综合介绍了近期国内外制作叠层片式电感、滤波器和变压器的LTCF(低温共烧铁氧体)工艺、低温烧结NiCuZn、MnZn、Co_2Z、Co_2Y、BaM等铁氧体技术以及LTCC(低温共烧陶瓷)叠层片式电感的研发进展,展望了LTCC和叠层片式电感的发展趋势.     

MnZn功率铁氧体的研究进展

介绍了MnZn功率铁氧体的研究现状及TDK等铁氧体公司的最新产品,阐述了MnZn功率铁氧体的基本配方、添加剂及烧结工艺,指出了功率铁氧体的发展方向.     

高磁导率MnZn铁氧体的氧化还原度调控与磁性能提升

采用氧化物陶瓷工艺制备MnZn铁氧体材料,研究了烧结过程氧分压及热处理氧分压对于其电磁性能的影响。实验表明,烧结过程中的氧分压P(O_2)越高,材料中的Fe²⁺含量越低,烧结体晶粒越大;氧分压的最佳范围在4~7%附近,过高或过低均会降低材料的磁性能。对于因氧分压偏离最佳范围导致磁性能低下的MnZn烧结体,可以通过后续的热处理工艺调节Fe²⁺含量以恢复其磁性能。根据这些结果,综合烧结工艺和热处理工艺的优势,采用21%的氧分压烧结获得较大的晶粒之后再在0.1%的氧分压气氛中热处理的方法调节铁氧体的Fe²⁺含量,获得了25℃时μi=10600,Bs=427 mT,μi(200 kHz)/μi(10 kHz)=98%,综合性能良好的高磁导率MnZn铁氧体磁芯。     

振动光整对MnZn铁氧体磁心环电磁性能和机械强度的影响

采用传统的氧化物法工艺制备低功率损耗及高μi软磁铁氧体磁心环,借助机械强度测量仪、HP4284A、SY-8232(B-H)测试仪和振动光整机,研究机械振动光整对烧后MnZn软磁铁氧体磁心环电磁性能和机械强度的影响.φ10mm×φ6mm×5mm磁心环的测试结果表明,振动光整一定时间对烧后MnZn软磁铁氧体磁心环的机械强度...     

烧结工艺对MnZn铁氧体磁性能的影响

在钟罩式气氛烧结炉中烧结高导MnZn铁氧体材料.研究发现,掺入适量的CaCO3和Bi2O3能改善材料的磁性能.烧结过程中烧结温度的增高可以促进晶粒长大,有利于提高起始磁导率;烧结气氛对离子电价和晶相形成有着决定性影响,选择合适烧结工艺是制备优质MnZn铁氧体的关键.     

如何选择"氮窑"

1 前言 众所周知,MnZn铁氧体是Mn、Zn和Fe三种金属的氧化物在高温下发生固相反应生成的,而在不同温度与气氛条件下Mn、Fe将发生离子价的变化,故为了保持在MnZn铁氧体中各金属离子的特定价态和尖晶石单相结构,除严格控制配方外,还必须严格控制热化学反应的温度和气氛条件[1].因而烧结就成为MnZn铁氧体生产过程中的关键工序,而烧结设备则是实施烧结的基本条件.     

承烧材料对MnZn铁氧体磁性能的影响

研究了莫来石承烧材料与底层磁芯之间的相互作用及其对MnZn铁氧体磁芯性能的影响。结果表明,受承烧材料影响,底层磁芯性能下降,其主要原因是Zn挥发引起的成分偏离。成分分析证实磁芯接触端面有Si4 渗透产生的侵蚀层(厚度约100μm);物相分析证实Al2O3与ZnO反应生成ZnAl2O4异相物质是Zn挥发的主要途径,两者同时作用导致材料性能严重恶化。     

气氛粉法防止锰锌铁氧体氧化的研究

MnZn铁氧体在烧结过程中,采用气氛粉如氧化铜复合粉、铁氧体粉末等能有效地减弱样品的氧化程度,它是一种防止MnZn铁氧体被氧化的新方法。实验表明:制备低,中磁导率的锰锌铁氧体,用气氛粉法比其它方法更为简便、有效,对改善材料的综合性能具有显著效果。     

叠层片式电感及低温烧结铁氧体的研发进展

介绍了叠层片式电感的现状及其低温共烧技术,特别就低温烧结NiCuZn、MgCuZn和Co2Z铁氧体粉料的研发进展作了详细报道.最后,展望了低温烧结铁氧体的发展趋势,指出缩小差距的研究方向.     

The Synthesis and Composition of Dual-Phase 3Y-TZP/RuO2 Electrode Powders

This research was performed to learn more about the electron conducting yttria doped zirconia/ruthenia dual-phase system. The study indicated that for all starting powder precipitates (by either co-precipitation or sequential precipitation) strong separation between the Ru and Zr-species upon heating occurred already at the unexpected low temperature of 100–200°C. The solubility of RuO₂ in 3Y-TZP (zirconia stabilised into a tetragonal phase by a 3 mol% Y₂O₃ addition) after calcination at 600°C was estimated at 3 mol%, independently of the used synthesis technique.     

烟气中氧量成份分析的可靠性探讨

比较了用于炉窑烟气中氧成份分析的多种测量仪器和测量方法,认为氧化锆氧量计是目前能够适于烟气含氧量实时在线监测的最为可行和最经济的方法。分析影响氧化锆测量精度和可靠性的因素,讨论氧化锆传感器用于锅炉排烟氧量测量时存在的问题。指出样气和参比气体的流通性、温度测量与控制的准确性、样气取样过程的合理性等是影响烟气中氧量分析结果准确性、可靠性、稳定性和重复性的三大主要原因。结合目前的应用现状,给出提高烟气中含氧量测量结果的可靠性和准确性、改进氧化锆传感器测量系统的措施。     

Electrochemical NOx sensors based on stabilized zirconia: comparison of sensing performances of mixed-potential-type and impedancemetric NOx sensors

A tubular sensor was fabricated by using yttira stabilized zirconia (YSZ) and ZnCr₂O₄ sensing-electrode (SE) aiming for detection of NOx at high temperature. The sensing characteristics of this YSZ-based sensor were evaluated at 700^∘C by means of potentiometric (mixed-potential) and impedancemetric methods with the variation of thickness of SE. A correlation between the thickness and the sensing performances was obtained for both types of NOx sensors. The mixed-potential-type sensor using ZnCr₂O₄-SE exhibited high NOx sensitivity when the SE thickness was small (4 μm). On the other hand, the impedancemetric sensor, employing the same oxide-SE, provided almost equal sensitivity to NO and NO₂ when the SE thickness was large (39 μm). In this case, the total concentration of NOx can be measured. The comparison of sensing mechanisms for the both sensors was briefly discussed.     

Modeling and Characterization of Electrical Transport in Oxygen Conducting Solid Electrolytes

A model for the electrical conductivity in acceptor-doped oxides which involves an association between the acceptor-dopants and oxygen vacancies resulting in donor centers is considered. The model relates the behavior of the electrical conductivity with the temperature, ambient atmosphere and band structure. The predictions of the model are compared to experimental data for ZrO₂:16% Y and SrCeO₃:5% Yb oxygen conductors and some band structure parameters have been determined.     

Interaction between Water and Ceria-Zirconia-Yttria Solid Solutions

We have investigated the water solubility, oxygen isotope diffusivity, and oxygen surface exchange coefficient in a humid atmosphere of the system {(CeO₂)_x(ZrO₂)_1–x}_0.8(YO_1.5)_0.2 (x = 0–1) by using isotope exchange and secondary ion mass spectrometry (SIMS). The deuterium ion (²D^–) was detected from the {(CeO₂)_x(ZrO₂)_1–x}_0.8(YO_1.5)_0.2 polycrystals which were annealed in D₂O containing atmosphere. The solubility of deuterium in the polycrystals increased with the cerium content (x). The oxygen exchange rate constant () in air at T = 973 K shows a maximum at x = 0.2–0.3, which can be correlated to the compositional dependence of electronic conductivity of {(CeO₂)_x(ZrO₂)_1–x}_0.8(YO_1.5)_0.2. The effect of water on the surface exchange rate constant was more significantly observed for the samples with higher content of cerium x > 0.6.     

离心沉积法制备YSZ薄膜及其性能

用离心沉积方法在NiO-YSZ阳极基底上沉积了氧化钇稳定的氧化锆(YSZ)薄膜,并在1 400℃烧结达到致密;用SDC的硝酸盐浸渍改进的LSM作为阴极,组装燃料电池。阳极通入干燥的H2作燃料,阴极直接暴露在空气中,单体电池在650℃的开路电压(OCV)为1.059 V,说明薄膜是完全致密的;800℃时的最高功率密度为535 mW/cm2。800℃时的阻抗谱表明,通过改变阳极端的气氛,可以区分出阴、阳极的阻抗。     

溶液燃烧法合成11ScSZ-2Mn_2O_3电解质粉体及其应用

采用硝酸盐-甘氨酸溶液燃烧法合成了(ZrO2)0.87(Sc2O3)0.11(Mn2O3)0.02(11ScSZ-2Mn2O3)粉体,通过X射线衍射仪(XRD)、透射电镜(TEM)、场发射扫描电镜(FESEM)及氮气吸附等手段对粉体进行表征。结果表明,所合成的11ScSZ-2Mn2O3粉体具有单一立方结构,比表面积达28.6m2/g,粒度均匀。非等温和等温烧结测试均表明该粉体具有良好的烧结活性,可在1200℃下烧结致密化。以11ScSZ-2Mn2O3粉体为原料配制电解质粉体浆料,采用浸渍-提拉法在NiO-氧化钇稳定氧化锆(YSZ)阳极基体上制备了电解质薄膜,在1250℃下实现了负载型薄膜的烧结致密化,与La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF)阴极组装了单元电池Ni-YSZ/11ScSZ-2Mn2O3/LSCF。该单元电池在中温下以H2为燃料表现出良好的电性能输出,在操作温度为650℃和700℃下的最大输出功率密度分别为0.55W/cm2和0.90W/cm2。     

Pt/YSZ电极结构形貌对传感器特性的影响

借助交流阻抗测试技术、汽车用A/F(空气与燃料的质量比)氧传感器响应时间测量装置及SEM,对敏感材料为Y2O3稳定ZrO2多晶固体氧离子导体(YSZ)的Pt/YSZ电极结构氧传感器其特性在不同烧结温度下电极形貌的关系进行了研究,同时提出了一种有关Pt/YSZ电极界面的形貌模型,采用此模型对不同烧结温度下的电极形貌Pt/空气/YSZ三相界面长度进行了定量计算.     

Measurement of topcoat thickness of thermal barrier coating for gas turbines using terahertz waves

The topcoat thickness of thermal barrier coating (TBC) samples was measured using terahertz (THz) waves. The index of refraction of yttria‐stabilized zirconia (YSZ), which is the topcoat material, is necessary to obtain the topcoat thickness from time domain re?ectometry. Time domain THz spectroscopy was applied to YSZ samples, and the index of refraction was measured to be 4.8 in the frequency region 0.1 to 1.2 THz. The topcoat thickness of six di?erent TBC samples, which varied from 300 to 600 µm, was measured using THz waves. The results were in agreement with microscope observation results to within measurement error. In addition, the topcoat thickness pro?le of a turbine blade sample was measured with a resolution of 2.4 µm. The pro?le showed a standard deviation of 4 µm, which re?ects the actual variation in the topcoat thickness. The results showed that THz waves are e?ective for high‐resolution measurement of the topcoat thickness. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(4): 1–9, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22385     

Highly enhanced electrochemical performance of silicon-free platinum–yttria stabilized zirconia interfaces

In the drive to achieve economically viable solid oxide fuel cells, efforts have been directed towards substantially decreasing their operating temperature. Unfortunately, these efforts have been hindered by extremely sluggish electrode kinetics at reduced temperatures. In this report, we show that silicon impurities on the surface of the electrolyte play a critical role in influencing electrode kinetics. More specifically, improvements by as much as three orders of magnitude are reported for the performance of platinum electrodes on yttria-stabilized zirconia electrolytes prepared as high purity thin films with a largely Si-free surface. These improvements in performance are estimated to enable operation of a solid oxide fuel cell down to approximately 400 °C.