低压双功能TiO2压敏陶瓷的研究

采用一次烧成工艺制备了具有电容性和压敏性双功能TiO2陶瓷.考察了Nb2O5施主掺杂对TiO2压敏陶瓷的显微结构、介电性能和压敏性能的影响.结果表明随Nb2O5掺杂量的增加,样品的晶粒粒径变大、晶界层变薄;压敏电压V1mA减小、非线性系数α和介电常数ε增大.当Nb2O5掺杂量为2 mol%时,TiO2压敏陶瓷有较好的压敏特性ε=22 000、V1mA=2.8 V和α=3.8.     

低压双功能TiO2压敏陶瓷的研究

采用一次烧成工艺制备了具有电容性和压敏性双功能TiO2陶瓷．考察了Nb2O5施主掺杂对TiO2压敏陶瓷的显微结构、介电性能和压敏性能的影响．结果表明：随Nb2O5掺杂量的增加，样品的晶粒粒径变大、晶界层变薄；压教电压V1mA减小、非线性系数。和介电常数ε增大．当Nb2O5掺杂量为2mol％时，TiO2压敏陶瓷有较好的压敏特性：ε＝22000、V1mA=2.8V和α=3.8。     

氧化热处理对一次烧成的SrTiO3复合功能陶瓷电性能的影响

采用一次烧成工艺制备ＳｒＴｉＯ３复合功能陶瓷，测试了样品的电学性能，研究了氧化热处理对样品电学性能的影响，结果表明，样品的复合功能特性同晶界特性紧密相关，氧化热处理直接影响晶界受主态的扩散和分布，随着氧化热处理温度的提高，非线性系数ａ和压敏电压Ｖ１ｍＡ增大，表观介电常数εｒ和介电损耗ｔｇδ减小。     

氧化热处理对一次烧成的 SrTiO_3 复合功能陶瓷电性能的影响

采用一次烧成工艺制备了ＳｒＴｉＯ３复合功能陶瓷，测试了样品的电学性能，研究了氧化热处理对样品电学性能的影响。结果表明，样品的复合功能特性同晶界特性紧密相关，氧化热处理直接影响晶界受主态的扩散和分布，随着氧化热处理温度的提高，非线性系数α和压敏电压Ｖ１ｍＡ增大，表观介电常数εｒ和介电损耗ｔｇδ减小。     

Sr掺杂对TiO2双功能压敏陶瓷介电性能的影响

着重探讨了Sr掺杂对TiO2双功能压敏陶瓷介电性能的影响。经研究发现，Sr掺杂能显著提高TiO2双功能压敏陶瓷的介电性能。随着Sr含量的变化，TiO2双功能压敏陶瓷的介电性能在一个很宽的范围内变化。当Sr含量增加时，介电常数εeff的变化规律是先减小后增大，增大到一定值时又减小，而介电损耗则是先减小后一直增大，可在协调εeff和tanδ的情况下，取得较好的实验结果。     

Mg-9Gd-3Y镁合金PEO-EPD复合膜层组织结构与耐蚀性研究

为了提高镁合金的耐蚀性,本文利用扫描电镜分析了Mg-9Gd-3Y(GW93)镁稀土合金表面等离子电解氧化陶瓷层、等离子电解氧化-电泳复合膜层和电泳膜层的表面与纵截面形貌组织,利用傅立叶红外光谱仪(FT-IR)分析了电泳膜层有机官能团类型,用电化学测试手段和盐雾试验方法测试了该合金不同处理膜层的耐蚀性,讨论了电泳电压和固体粉料分数对等离子电解氧化-电泳复合膜层厚度、成膜速率和耐蚀性的影响.研究结果表明,随着电压、固体份的升高,等离子电解氧化-电泳复合涂层厚度和成膜速率呈增大趋势,腐蚀速率随着电压升高呈先减小后增大的趋势,随着固体份的增加呈降低趋势.电泳电压为70V,固体份为19%时,在等离子电解氧化膜层上生成陶瓷层与有机化合物层结合紧密的等离子电解氧化-电泳复合膜层,腐蚀电流密度比等离子电解氧化膜层降低两个数量级,自腐蚀电位正移200mV,耐蚀性提高近13倍.     

氧化锌压敏陶瓷的制备与表征

简析纳米氧化锌压敏陶瓷材料的概念、特性、表征、应用现状,以及制备纳米氧化锌的常见方法和工艺流程,并探讨了纳米氧化锌压敏陶瓷的结构、电参数和导电机理.     

铜颗粒分散铌酸钾钠压电复合材料的制备与性能

在工业氮气(N2)气氛条件下制备了锂掺杂铌酸钾钠/铜(NKLN/Cu)压电复合材料,研究了铜含量对复合材料的相结构、密度、电学性能及力学性能的影响。结果表明:复合材料由NKLN陶瓷相和Cu金属颗粒两相组成,不同Cu含量复合材料的相对密度均达到95%以上。复合材料的介电常数随Cu含量的增加而急剧增加,压电常数和机电耦合系数随Cu含量的增加而减小,当Cu的体积分数达到20%时,NKLN/Cu复合材料的介电性能和压电性能均难以测量。NKLN/Cu复合材料的显微硬度随Cu含量的增加而降低,断裂韧性值随Cu含量的增加而升高,从铌酸钾钠陶瓷的1.01 MPa逐渐增至Cu的体积分数为40%时的2.81 MPa。     

不同造孔剂对CaCu3Ti4O12多孔陶瓷介电性能的影响

以碳粉和蛋清作为造孔剂,利用固相法制备CaCu3Ti4O12(CCTO)多孔陶瓷.研究了造孔剂含量对CCTO多孔陶瓷体积密度、显微结构和介电性能的影响.结果表明,随着碳粉含量增加,体积密度先增加后减小;而随着蛋清含量增加,体积密度先减小后增加.和碳粉相比,蛋清加入制备的试样具有较小、较均匀的孔隙.当频率大于331.5KHz时,添加碳粉可以降低介电损耗.当频率大于4KHz时,添加碳粉介电常数有所下降.当频率大于2KHz时,添加蛋清可以增大介电损耗,但是增加幅度较小.添加蛋清可以增大介电常数.     

Ti基体上形成微弧氧化膜组成和结构的研究

在甘油磷酸钙和醋酸钙电解液中采用直流电源对纯Ti进行了微弧氧化。采用微弧氧化方法所制备的氧化膜具有粗糙多孔的结构,且微孔直径随着电压的增加而增大。AES分析表明在基体与氧化膜界面发生了扩散,从基体钛到氧化膜的表面氧的浓度逐渐增大,钛的浓度逐渐减小。XPS分析表明氧化膜的组成随着所施加的微弧氧化电压而改变,微弧氧化电压为200V时TiO2、Ti2O3和TiO占Ti的原子百分比分别为72．61％、22．08％和5.31％;当微弧氧化电压为350V时氧化膜表面Ti元素只由TiO2、Ti2O3组成,且占Ti的原子百分比分别为85．48％、14．52％。     

Influence of Ag doping on the microstructure and electrical properties of ZnO-Bi2O3-based varistor ceramics

Silver in the form of AgNO3 was added to ZnO-based varistor ceramics prepared by the solid-state reaction method.The effects of AgNO3 on both the microstructure and electrical properties of the varistors were studied in detail.The optimum addition amount of AgNO3 in ZnO-based varistors was also determined.The mechanism for grain growth inhibition by silver doping was also proposed.The results indicate that the varistor threshold voltage increases substantially along with the AgNO3 content increasing from 0 to 1.5mo1％.Also,the introduction of AgNO3 can depress the mean grain size of ZnO,which is mainly responsible for the threshold voltage.Furthermore,the addition of AgNO3 results in a slight decrease of donor density and a more severe fall in the density of interface states,which cause a decline in barrier height and an increase in the depletion layer.     

ZnO varistors with high voltage gradient and low leakage current by doping rare-earth oxide

The surge arrester of 1000 kV gas-insulated substation (GIS) needs ZnO varistor with high voltage gradient to effectively improve the potential distribution along ZnO varistor column inside the metal-oxide surge arresters. In this paper, the electrical and structural parameters of ZnO varistors are changed by doping with some rare-earth oxides, and the mechanism which leads these changes is discussed. When rare-earth oxide additives are added into ZnO varistors, the growing speed is slowed down due to the stabilization of the new spinel phases formed in the grain-boundary by rare-earth oxide additives, then the size of ZnO grains is smaller, and the voltage gradient of varistor increases obviously. By adding suitable amount of oxides of metal Co and Mn, the leakage current can be effectively decreased and the nonlinearity coefficient increased. The novel ZnO varistor samples sintered with the optimal additives have a voltage gradient of 492 V/mm, and the nonlinearity coefficient of 76, but their leakage currents are only 1 μA. Supported by the National Nature Science Foundation of China (Grant Nos. 50425721 and 50737001), and the 11th Five-Year National S&T Supporting Plan (Grant No. 2006BAA02A16)     

氧化锌压敏电阻器固有电容的研究

以氧化锌半导体陶瓷的微观模型为基础,分析影响氧化锌压敏电阻器固有电容量的各种因素,重点分析如何控制氧化锌压敏电阻器固有电容量的问题。给出了有关实验数据并对实验结果进行了讨论,得出了在理论上和实践中有意义的结论。     

钐和锌双掺杂La9.33（SiO4）6O2电解质的制备及其电导率

为提高磷灰石型电解质（LSO）的电导率,以氧化镧（La₂O₃）、氧化锌（ZnO）和氧化钐（Sm₂O₃）为主要原料通过尿素-硝酸盐燃烧法在600 ℃的温度下合成了掺杂钐和锌的La_9.33Sm_xSi₅ZnO_{（25+1.5x）}固体电解质粉末。采用X射线衍射、扫描电子显微镜、变温介电测量系统对样品进行物质结构、表面形貌、电导率的表征。研究了不同温度和不同掺杂浓度下La_9.33Sm_xSi₅ZnO_{（25+1.5x）}的电导率。结果表明,Sm和Zn成功掺杂进入LSO的晶格中,样品具有典型的P6₃/m磷灰石结构且纯度高,LSO的形貌未改变。当Sm掺杂浓度为0.6,Zn掺杂浓度为1时,在温度为650 ℃下La_9.33Sm_xSi₅ZnO_{（25+1.5x）}的电导率达到1.50×10^-3 S/cm;确定了最佳烧结温度为1 400 ℃。La_9.33Sm_xSi₅ZnO_{（25+1.5x）}的电导率在同一温度下随着掺杂量的增加先提高后降低,掺杂样品的晶胞参数相比于未掺杂样品的晶胞参数增大,活化能随着掺杂量的增大先降低后升高。此外La_9.33Sm_xSi₅ZnO_{（25+1.5x）}的电导率在同一掺杂量下,随着温度的升高而提高。     

Influence of soaking time on nonlinear electrical behavior and dielectric properties of TiO2-based varistor ceramics

The influence of soaking time on the nonlinear electrical behavior and dielectric properties of TiO₂-based varistor ceramics was investigated. Based on single sintering process, six disk samples of (Sr, Bi, Si, Ta)-doped TiO₂-based varistor ceramics were fabricated by sintering at 1 250 °C for 0.5–5.0 h. The samples were characterized by X-ray diffraction, voltage-current characteristics, energy spectra, metallographs, breakdown voltages, and apparent dielectric constant. It is found that the breakdown electrical field intensity at a current density of 10 mA/cm² decreases from 5.5 to 4.1 V/mm first and then increases to 7.0 V/mm, the nonlinear coefficient increases from 2.39 to 2.62 first and then decreases to 2.42, and the apparent dielectric constant increases from 98 200 to 115 049 first and then decreases to 73 865 with the soaking time increasing from 0.5 to 5.0 h. These indicate that the optimal soaking time is 2.0–3.0 h considering both nonlinear electrical behavior and dielectric properties.     

Er掺杂ZnO-Bi2O3系亚微米柱状晶体及其压敏电阻性能

制备了Er掺杂ZnO-Bi2O3系烧结形成亚微米长柱状晶体;用X—射线衍射仪分析了ZnO-Bi2O（3Er）系物相成分;用电子显微镜观察ZnO-Bi2O（3Er）系亚微米长柱状晶相特征,晶体的长径比约为17;最后对其进行了压敏电阻性能的检测,随Er2O3含量的增加,ZnO纳米长柱状晶体向颗粒状过渡,电位梯度逐渐增大,非线性系数呈升高趋势,漏电流偏低,并且渐渐平缓.     

n型半导化TiO2压敏陶瓷的导电机制

分析了n型半导化TiO2压敏陶瓷中晶粒间界处的受主态性质，得出为晶界受主态的能级是多级化的；利用晶界平衡热电子发射势垒模型，合理地解释了该材料的I－V非线性特征；从理论上推导出了非线性系数α正比于晶界电压，且与晶界受主态的分布函数有密切关系。     

多重雷击下线路避雷器氧化锌阀片的劣化特性试验研究

多重雷击会加速劣化氧化锌阀片,造成阀片的电、热性能急剧下降,不同多重雷击参数下氧化锌阀片的破坏具有显著差异性。为此,本文开展了不同多重雷击参数对氧化锌阀片劣化特性的研究：首先搭建了多重雷击试验研究平台,对阀片进行了单重1倍额定电流、单重1.5倍额定电流、4重1倍额定电流、单重1.5倍额定电流和12重1倍额定电流的5种工况冲击试验,测试了阀片的直流参数和温升,进而分析了多重雷击参数对试验结果的影响,最后对阀片的非线性系数、热应力和破坏形式进行了讨论。结果表明：不同工况下直流参考电压变化均呈“下降—平稳—下降”趋势,4重出现直流参考电压陡降现象,12重出现泄漏电流陡升现象;1.5倍额定电流工况下阀片泄漏电流在前期与标称电流工况的变化幅度相近,后期时急剧劣化;非线性系数也存在“下降—平稳—下降”规律,增大冲击重数和幅值会使非线性系数下降趋势增大;冲击重数和幅值增大使阀片外圈处最大热应力增加,阀片外圈出现不同长度的缺块。     

Influence of grain size on distribution of temperature and thermal stress in ZnO varistor ceramics

The nonuniformity of temperature distribution within ZnO varistor ceramics would decrease its energy absorption capability. In this paper, the distributions of current, temperature and thermal stress within the microstructures of ZnO varistor ceramics are simulated using Voronoi diagram models. The results show that the current concentrates through a few paths in ZnO varistor due to the nonuniformity of ZnO grain size and the variety of electrical characteristics of grain boundaries, which induces local high temperature and great thermal stress when injecting impulse current into ZnO varistor, and leads to melting puncture or cracking failure. The influence of the ZnO grain size on the distributions of temperature and thermal stress within ZnO varistor ceramics is analyzed in detail. The energy absorption capability of ZnO varistor ceramics can be greatly improved by increasing the uniformity of ZnO grain size or decreasing the average size of ZnO grains.     

Microstructures and characteristics of deep trap levels in ZnO varistors doped with Y2O3

In this paper discussions on ZnO based varistor ceramics doped with different ratios of Y₂O₃ are presented. Analysis on the phase and microstructures of the samples indicates that an additional phase is detected in the samples doped with Y₂O₃, and the average grain size of the specimens decreases from about 9.2 μm to 4.5 μm, with an increase in the addition of Y₂O₃ from 0 mol% to 3 mol%. The corresponding varistor’s voltage gradient markedly increases from 462 V/mm to 2340 V/mm, while the nonlinear coefficient decreases from 22.3 to 11.5, respectively. Furthermore, the characteristics of deep trap levels in these ZnO samples are investigated by measuring their dielectric spectroscopies. The trap energy level and capture cross section evaluated by relaxation peak of the Cole-Cole plot vary slightly as the addition of Y₂O₃ increases. These traps may be ascribed to the intrinsic defects of ZnO lattice.