排序方式: 共有23条查询结果,搜索用时 0 毫秒
1.
A technique based on viscous polymer processing (VPP) was described, which can produce high ceramic content green fibers. PZT-5 ceramic powders were ball milled to get high dispersibility. The slurry prepared for VPP was a composition of PZT-5 powder, PVA binder and glycerin. High ceramic content PZT-5 fibers were extruded with the slurry. The results show that the ceramic powders have fine mean particle size of 0.54 pan, high specific surface area of 3.55 m^2/g and zeta potential of 8.81 mV after 16 h milling. The fibers sintered at 1 280 ℃ for 4 h have pure perovskite structure and grains of 2-5 μm in size, with little pores or cracks. The ultimate tensile strength of sintered fibers is up to 13.84 MPa compared with 2.88 MPa of green fibers. The remnant polarization (Pr) and coercive field (Ec) of the fibers are 50.65 μC/cm^2 and 2.45 kV/mm, respectively. This fiber can withstand an electric field of 9 kV/mm higher than the ceramic (5 kV/mm), which shows high directional and compact qualities. 相似文献
2.
当前,信息技术正以惊人的速度改变着人们的生存和学习方式.信息技术是当前各类学校教育的重要内容,也是教育改革的重要技术手段.信息技术与学科教学的整合,提高了教育的智能化水平和幼儿在教育中的主体地位.基于这样的考虑,我园在"十一五"期间申报实施了苏州教育科学规划重点课题<信息技术与幼儿园教学整合策略之研究>. 相似文献
3.
固相法制备BaTiO3基细晶陶瓷粉体 总被引:1,自引:0,他引:1
通过传统的固相法制备BaTiO3基细晶陶瓷粉体,讨论了在预烧温度和烧结温度相同的情况下,探讨不同施主元素的添加量对陶瓷晶粒及电性能的影响;在预烧温度和烧结温度相同的情况下,探讨不同受主杂质对陶瓷晶粒及电性能的影响;在施、受主掺杂量及烧结温度相同的情况下,探讨不同的预烧温度对陶瓷晶粒及电性能的影响.为了制备高升阻比、晶粒细小的BaTi03陶瓷,选取的材料配方为Ba1.0Ti1.01O3+0.4%(摩尔分数)Y2O3+0.03%(摩尔分数)Mn(NO3)2+2%S102,粉体在1200℃预烧,保温2h,样品在1280℃烧成。上电极后测得常温电阻率为4937Ω·cm,升阻比为7.116×10^3,温度系数为14.03%,居里温度为128.4℃. 相似文献
4.
5.
The green sheets with Ni paste as inner electrodes were sintered at 1 320 ℃ for 1 h under a N2/H2 mixing gas at an oxygen partial pressure p(O2)=10-8-10-12 MPa, and then reoxided at 900-1 000 ℃ to form multilayer positive temperature coefficient of resistance(PTCR). During the experiments, electronic characteristic effects of PTC with different thicknesses were contrasted. A certain extending of Ni diffusion is beneficial to the ohmic contact of multilayer PTCR but excessive diffusion is harmful to PTCR. The diffusion was studied by scanning electron microscopy(SEM) and energy-dispersive X-ray spectrometry(EDS). Inter-diffusion of element takes place along the Ni-BaTiO3 interface, especially Ni diffusion to BaTiO3 dominated the process. Furthermore, the degree of Ni diffusion is very severe as ceramic layers are very thin. 相似文献
6.
以溶胶-凝胶法制备了BaTiO3基PTCR纳米陶瓷粉体,通过适当控制材料的掺杂量和烧成制度达到细化晶粒、降低烧结温度及降低室温率的目的。讨论了溶胶.凝胶过程中水的加入量、乙酸加入量、乙醇加入量、成胶温度对形成细晶粉体的影响,制备出的BaTiO3粉体具有纯度高、粒径小、均匀性好、活性高、热处理温度低等优点。R-T丁曲线表明1260℃较1240℃烧结具有高的升阻比、温度系数,低的电阻率、居里温度:XRD分析表明所得粉体与BaTiO3主峰相吻合;800℃预烧2h所得BaTiO3粉体的TEM图表明粉体分布较均匀、外形为近似球形,其平均晶粒尺寸约30nm左右,与XRD得到的晶粒相当,单个颗粒是单晶;1240℃下烧结所得样品的SEM图片看出样品的平均晶粒约1~2μm、晶粒较为均匀致密。 相似文献
7.
8.
乙烯是石油化学工业中最重要的基础有机原料之一。通常乙烯采用低温常压存储,因此存储的能耗对乙烯储运的运行成本影响较大。本文通过对低温乙烯存储系统中不同的工艺能耗进行了分析和比较,发现节能技术的应用能回收乙烯冷量,有效的降低乙烯存储的能耗,为低温乙烯存储系统中的节能技术的应用提供参考。 相似文献
9.
10.
采用共沉淀法经水热反应合成了棒状有序介孔锌掺杂氧化硅(mesoporous zinc-doped silica,MZS)材料,借助X射线衍射、Fourier变换红外光谱、光电子能谱、透射电镜、N2吸附-脱附、光致发光光谱等测试手段对有序介孔结构及光学性能进行了表征.结果表明:合成材料具有高度的长程有序结构,虽然锌的掺杂引起材料的比表面积的减小,但仍能保持介孔材料的有序性.合成材料中的Zn2 已经进入Si-O骨架并产生大量Si-O-Zn交联键,进而引发了MZS介孔材料的蓝色荧光发射强度显著增强且有明显蓝移. 相似文献