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微波等离子烧结ZnO/Bi2O3系压敏电阻研究 总被引:3,自引:0,他引:3
采用常规微波和微波等离子对比烧结ZnO/Bi2O3系压敏电阻发现:两者均可快速成瓷,烧结时间由常规的20 h减少到45 min;烧结后,ZnO晶粒细小(约1μm)均匀,相比而言,等离子更有利于压敏电阻烧结。45 min等离子烧结后,压敏电阻瓷体密度为5.01 g/cm3,ZnO压敏电阻中已有尖晶石相(Zn7Sb2O12)生成,烧结时瓷体收缩均匀,漏电流小,但稳定度差。采用“液相掺杂”可以提高压敏电阻在微波等离子烧结后的电性能稳定度,液相加入比例范围为5%~15%。 相似文献
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基于直接激光金属烧结成形技术,以FGH95镍基高温合金粉末为研究对象,讨论了烧结工艺参数对制件微观组织、体积密度及显微硬度的影响。制件微观组织结构由等轴晶和枝状晶组成,在较高的激光功率、较低的扫描速度和较小的扫描间距时,等轴晶数量减少,尺寸增加,而枝状晶数量多且晶粒细微。制件的体积密度随着激光功率的提高而增大,随着扫描速率和扫描间距的增大而减小;随着激光功率和扫描速度的提高,制件的显微硬度呈先降后升趋势;随着扫描间距的增大,制件的显微硬度呈递增趋势,在到达最大值时有明显的回落。采用激光功率为900 W,扫描速度为0.8 m/min,扫描间距为0.6 mm以及粉层厚度为0.9 mm的参数组合,可获得表面平整、体积密度高、晶粒均匀细小和无明显微观缺陷的制件,其显微硬度可达到477 HV。 相似文献
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利用放电等离子体烧结(SPS)技术制备了粗晶(13μm)和细晶(2μm)两种镍样品.EBSD分析表明,两种烧结样都没有织构,且它们的晶粒都为完全再结晶组织.对此烧结样进行单轴压缩,研究晶粒尺寸对形变中微观组织演变的影响.在样品坐标系中,用每个像素点相对于平均取向的旋转轴来构图,结果显示在一些大晶粒中有扩展的平直界面.滑... 相似文献
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The change of electrical resistivity of materials during sintering has been investigated. The evolution of two-dimensional
microstructures during sintering was evaluated using Monte Carlo simulation featuring neck formation, grain growth, and contraction
of the powder compacts. The overall electrical resistivity of the sintered microstructure, calculated by Kirchhoff’s first
law, was related to the microstructure development during sintering, depending on microstructural parameters such as size
and distribution of grains and pores. The solid-state sintering process of monosized particles was divided into three regimes:
neck formation, densification, and grain growth. The resistivity dropped significantly at the very initial stage due to neck
formation, and decreased slowly as pores were annihilated, while it remained almost unchanged after complete pore removal.
For the sintering of randomly packed random-sized particles, the electrical resistivity dropped at the initial stage due to
the neck formation, and then continuously decreased by a combined effect of compact densification and grain growth. 相似文献
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分别以CaO、MgO、SiO2简单氧化物和它们的预烧结体作为添加剂加入到质量分数为95%氧化铝中,并于1600℃烧结。用XRD分析了这两种形式添加剂烧成的样品物相组成,用SEM观察其表面和断面的微观形貌,进行抗弯强度试验。结果表明:与加入简单氧化物助剂的氧化铝陶瓷相比,加入预烧结助剂的氧化铝陶瓷可以实现更充分的液相烧结,烧成时间明显缩短,陶瓷相对密度可达到98%以上,晶粒尺寸为5μm左右,抗弯强度大于300MPa。 相似文献