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烧结温度对低压ZnO压敏陶瓷显微结构及电性能的影响 总被引:7,自引:0,他引:7
利用XRD,SEM等技术,研究了ZnO-Bi2O3-TiO3系低压压敏电阻材料的相民及显微组织,并对不同烧结温度下的电性能进行了研究。结果表明,在1150-1200℃范围内,可通过改变烧结温度调材料的压敏电压值,而材料的非线性系数a变化不大。 相似文献
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为了研究ZnO压敏电阻组成中非化学配比氧化物对ZnO压敏电阻导电性能的影响,采用在不同氧分压条件下烧结样品以研究其烧结行为。结果表明:ZnO晶粒的电导率对数与氧分压对数成线性关系;斜率为-1/4;间隙Zn原子以一价电离Zni形式存在。由于CoO,MnO和NiO阳离子空位氧化物多偏析于晶界,晶界处氧的增加有利于降低压敏电阻漏电流,烧结时间从2h延长到8h,漏电流从5μA/cm^2降到3.6μA/cm^2。波谱分析表明:掺杂氧化物在晶界处都有偏析,ZnO晶粒中掺杂原子混溶比例不完全与掺杂阳离子半径相关。 相似文献
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PBO纤维因其具有高强度、高模量、高耐热性以及高化学稳定性等性能而被公认为目前综合性能最好的有机纤维。对自制的初生PBO纤维分别在500℃、550℃、600℃、650℃和700℃进行高温热处理,并对处理后纤维的力学性能、耐热性能、表面形貌以及界面性能进行测试。结果表明,500℃下热处理后PBO纤维拉伸强度最大为4.72GPa,随着热处理温度升高,纤维的力学性能下降;600℃下热处理后PBO纤维的初始分解温度最高为641.3℃;随着热处理温度的提高,PBO纤维的表面粗糙度在增加,同时其界面剪切强度(IFSS)也随着温度的升高而增大。 相似文献
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Effect of Heat Treatment Temperature on Properties of Chinese Calcined Flint Clay Based Plastic Refractories 总被引:6,自引:1,他引:5
ZHANG Wei DAI Wenyong YU Xinfeng LI Liang Plibrico Industries Co. Ltd. Dalian China 《中国耐火材料》2009,18(2)
Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material,aluminum sulfate and fireclay as binding system.The results showed that with temperature rising,Chinese calcined flint clay based plastic refractories shrinked firstly and then expanded.The modulus of rupture (MOR) and the cold crushing strength (CCS) increased firstly and then decreased from 110 ℃ to 600 ℃,then increased obviously.Thermal expansion coefficient increased from 110 ℃ to 760 ℃,decreased from 760 ℃ to 1 300 ℃,and increased from 1 300 ℃ to 1 500 ℃. 相似文献
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《Ceramics International》2016,42(4):4739-4747
The influence of doping with Ge on the nonlinear coefficient α and the breakdown electric field EB of TiO2–Ta2O5–CaCO3 varistor ceramics was investigated. In this study, TiO2–Ta2O5–CaCO3 varistor ceramics added with Ge was successfully prepared using the traditional method of ball milling–molding–sintering. The electrical performance, including the nonlinear coefficient α, the breakdown electric field EB, and the leakage current JL, are tested using a varistor direct current parameter instrument. The average barrier height ΦB of each sample is calculated using the relevant formula. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and scanning transmission electronic microscopy analyses demonstrated that Ge doping notably changed the microstructure of TiO2–Ta2O5–CaCO3 ceramics, thereby increasing α and decreasing EB. When the doping contents of Ta2O5 and CaCO3 were 0.2 and 0.4 mol%, respectively, the optimum doping content of 0.9 mol% Ge exhibited high α (10.2), low EB (14.1 V mm−1), and high ΦB (0.95 eV). These results are superior to previous findings. In addition, Ge as sintering aid reduced the sintering temperature caused by the low melting point. The optimal sintering temperature was 1300 °C for the TiO2–Ta2O5–CaCO3 ceramics doped with Ge. 相似文献
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Effect of Heat Treatments on the Wetting Behavior of Bismuth-Rich Intergranular Phases in ZnO:Bi:Co Varistors 总被引:1,自引:0,他引:1
Jeffrey P. Gambino W. David Kingery Gordon E. Pike Lionel M. Levinson Herbert R. Philipp 《Journal of the American Ceramic Society》1989,72(4):642-645
The effect of annealing on the wetting behavior of Bi-rich intergranular phases in ZnO:Bi:Co varistors was studied. The intergranular phase exhibits temperature-dependent grain-boundary wetting, with an average equilibrium dihedral angle of 0° at 1140°C and over 55° at 610°C. The temperature-dependent wetting may be related to the temperature dependence of the ZnO concentration in the Bi2 O3 liquid phase. The effect of the intergranular phase distribation on the electrical properties of ZnO varistors is discussed. 相似文献
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热处理对离子交换法制备光致变色玻璃光色性能的影响王民权,陈庆云,樊先平(浙江大学材料科学与工程学系310027)EffectofHeatTreatmentonthePhotochromicPropertiesofPhotochromicGlassby... 相似文献
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焊后热处理是将压力容器放在热处理设备中加热到适当的温度,并在此温度中保持一定时间后,以不同速率冷却的一种工艺方法.焊后热处理的主要目的是为了消除残余应力和反作用力,使接头中的淬硬组织回火.焊后热处理的主要方法有炉内整体热处理、炉内分段热处理、整体炉外热处理、局部热处理等.热处理一般不改变压力容器用材料的形状和整体材料的化学成分,而是通过改变压力容器材料的微观组织结构,或改变工件表面材料的化学成分,改善材料的力学、物理和化学性能,从而提高材料的强度、硬度或改善其韧性,使材料达到要求的使用性能.本文对压力容器的热处理,进行简短的概括. 相似文献
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聚乙烯薄膜经过电晕处理后,热封温度提高,热封强度降低。这可通过降低电晕处理强度,适当延长热封时间和添加一定比例的mLLDPE树脂,以减小电晕处理对聚乙烯薄膜热封性能的影响。 相似文献
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以四川石化80万t/a乙烯装置急冷油塔焊后热处理为例,对热处理工艺技术进行了探讨。分析了热处理工艺参数的控制,如何采取合理的加热方式及防变形措施,对塔类设备的热处理具有一定的借鉴和指导意义。 相似文献