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1.
Jian -Ping Wang He -Lie Luo Nai -Fei Gao Yuan -Yuan Liu 《Journal of Materials Science》1996,31(3):727-730
The Fe-Ag granular metal solid samples with 10% and 30% weight iron have been successfully fabricated using a sol-gel method, which are characterized by X-ray diffraction and transmission electron micrography. The average diameters of iron particles are from about a few nanometres to a few tens of nanometres controlled by the reducing temperature. The evolution of magnetic properties and microstructure during heat treating are described in detail and explained by using the superparamagnetism, single domain and multi domain theories. The magnetic anisotropy of the Fe-Ag granular solid is studied by using the law of approach to saturation. It is found that the magnetic anisotropy constant is in the order of 105 J m–3 which is higher than the value of the bulk iron and increases with the increase of reducing temperature. 相似文献
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随着我国的教育体制改革和信息化建设的开展,应用型人才培养模式越来越得到国家的重视,计算机专业作为高校基础应用学科,必须改变培养模式以满足社会需求,本文分析了当前高校计算机应用能力的培养现状,提出从转变教学理念、改善教学方法,建设信息化学习资源,加强学科整合,提升大学生信息素养以增进创新力和竞争力四个方面进行计算机应用能力的培养,并反思可能遇到的问题以便为后续的相关研究提供借鉴和参考。 相似文献
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采用电位—电容法及Mott-Schottky分析技术研究了自腐蚀电位条件下防锈油膜在5% Na2SO4溶液中失效过程的导电机制转变行为.防锈油膜在5% Na2SO4溶液中的失效过程存在半导体导电特征,随着浸泡时间的延长,防锈油膜从浸泡初期的p型半导体转变为n型半导体,转变过程中,防锈油膜中出现两个空间电荷过渡层.随着浸泡时间的延长,防锈油膜中的空间电荷层厚度皆逐渐减小,载流子密度则逐渐增加,并且计算了不同转变时期防锈油膜中的电子给体(ND)和电子受体(NA)密度大小. 相似文献
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Some thermomechanical properties such as expansion, transition temperature and high-temperature viscosity of phosphate glasses with different P2O5 and BaO compositions have been measured. Absorption and fluorescence spectra of the phosphate glasses with different Er3+ doping have also been measured. The Er3+ doping concentration with respect to the maximal fluorescence intensity is 0.75 mol %. The attenuation of the fibre at a wavelength of 1.53 m is 12.8 db m–1. Upconversion of 1.064 m NdYAG laser pulses into intense green 547 and 667 nm light in the 0.75 mol % Er3+-doped phosphate glass fibre has been achieved. The output power of the two fluorescence signals of green 547 nm and red 667 nm are 178 and 42 W, respectively, with an upconversion efficiency of 1.78×10–2% and 4.2×10–3% respectively. 相似文献
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The dynamic vulcanization process, usually used for the preparation of thermoplastic elastomers, has been applied to prepare
polypropylene (PP)/polyurethane (PU) blends. BoltornTM H20 (H20) hyperbranched polyester containing 16 hydroxyl end gropus and pentaerythritol are used as curing agents, respectively,
for curing PU oligomer during blending with molten PP. To improve the compatibility of cured PU particles with PP matrix,
H20 is partly functionalized with stearic acid. The morphology, mechanical properties, thermal properties and melt flow index
(MFI) of the PP/PU blends with different curing agent are investigated. Compared with pentaerythritol, SEM photographs show
that H20 partly functionalized with stearic acid effectively reduces the size and size distribution of cured PU particles
in PP/PU blends which also is proved by MFI measurement. Consequently, the dynamically cured PP/PU blends with modified H20
have better mechanical properties than those cured with pentaerythritol. The shifts of crystallization peaks to higher temperatures
for all PP/PU blends indicate that PU particles in the blends can act as effective nucleating agents. Moreover, due to the
smaller size of PU particles PP/PU blends cured with modified H20 have higher crystallization temperatures than those blends
cured with pentaerythritol at the same PU content. 相似文献
8.
聚碳酸亚乙酯多元醇制备湿固化聚氨酯热熔胶及其性能研究 总被引:2,自引:0,他引:2
以聚碳酸亚乙酯多元醇(PEC)、二苯基甲烷4,4'-二异氰酸酯(MDI)和1,4-丁二醇(BDO)为主要原料,采用预聚物法合成了一种新型的湿固化聚氨酯热熔胶,并用聚四氢呋喃二醇(PTMG)型和聚己内酯二醇(PCL)型湿固化聚氨酯热熔胶进行性能比较.结果表明,热熔胶中多元醇种类、催化剂及异氰酸根(-NCO)含量对热熔胶的性能有较大的影响.用预聚物法合成的PEC型聚氨酯热熔胶具有较好的拉伸强度、粘接强度、耐水性能和可生物降解性,是一种新型环保粘接材料. 相似文献
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