共查询到20条相似文献,搜索用时 62 毫秒
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Al2O3陶瓷基体中原位生成TiB2和Ti(C,N)研究 总被引:6,自引:0,他引:6
采用原位反应法结合热压工艺制备Al2O3-TiB2-Ti(C,N)复相陶瓷,用TiO2,B4C,BN,Al及Al2O3为原料,通过组成设计可以制备出不同相组成及碳氮比的复相陶瓷。由SEM及TEM发现在Al2O3晶粒中分布着亚微米至微米级的近圆形Ti(C,N)颗粒,而在TiB2晶粒中分布着纳米级的板状Ti(C,N)晶体,并对这种显微结构的形成机理及化学反应过程作用初步分析。 相似文献
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新型高效催化剂气相聚合制备聚乙烯 总被引:5,自引:0,他引:5
综合报道了新型乙烯气相聚合MG型催化剂的制备及其聚合反应性能。研究了采用浸渍反应法制备含TiCl4/MgCl2/ZnCl2/SiO2醇/Al(i-Bu)3的MG-4型高效催化剂。在压力1.0MPa下,乙烯聚合催化效率高达445 ̄884kgPE/gTi,制得了表观密度≥g/0.37/cm^3、重均颗粒分布(20 ̄200目)≥97.7%、颗粒状态良好的聚乙烯。用DSC、SEM、WAXD对聚合产物进行了 相似文献
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新型高活性催化剂乙烯气相聚合的研究:共聚反应动力学及共聚?… 总被引:1,自引:0,他引:1
研究了新型高活性催化剂TiCl4、Ti(OBu)4/MgCl2、SiO2、ZnCl2/醇/AlR3体系催化乙烯和1-丁烯气相共聚反应的规律和动力学。 相似文献
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负载钛-三异丁基铝体系催化1-丁烯聚合 Ⅰ.聚合条件对1-丁烯聚合的影响 总被引:16,自引:5,他引:11
考察了负载钛(Ti)-三异丁基铝(Al)催化体系聚合条件对1-丁烯(Bt)聚合的影响。实验表明,该催化体系对Bt聚合催化效率可达34.8kg/g,聚合物为全同立构和无规立构聚1-丁烯的混合物。在一定的Ti/Bt(摩尔比)下,随着Al/Ti(摩尔比,下同)的增加和温度的升高,转化率都是先升高后下降,最佳Al/Ti值为300,温度为30℃。聚合物的相对分子质量和全同立构PBt含量均随Al/Ti和温度升高而逐渐下降。 相似文献
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甲基丙烯酸固相接枝聚丙烯及其增容研究 总被引:14,自引:0,他引:14
本文研究了甲基丙烯酸固相接枝聚丙烯及其增容效果。讨论了反应温度、反应时间、引发剂BPO浓度、单体MAA浓度对接枝率的影响,接枝物用红外光谱进行表征。结果表明:当实验条件在反应时间为2.5h,反应温度为115℃,BPO用量为1.5%、MAA/PP为0.20/1时,可获得最大接枝率12.5%。红外光谱分析证明PP已接枝上MAA,得到了PP-g—MAA接枝共聚物。固相接枝PP-g-MAA可作为PP-高岭土复合材料的增容剂,它明显改善了两相的相间结合,改善了复合材料的力学性能。 相似文献
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SiC晶须对Al2O3/TiB2/SiCw陶瓷刀具材料高温断裂韧性的影响 总被引:3,自引:0,他引:3
研究了不同SiC晶须含量的Al2O3/TiB2/SiCw陶瓷刀具材料的断裂韧性随温度的变化规律。结果表明:Al2O3/TiB2/SiCW陶瓷材料的K1C在1000℃内随温度的升高而增大;晶须含量越大,通过计算分析表明,随温度的升高粘裂时拔出的晶须大大增多,当晶须体积含量(下同)为20%时,Al2O3/TiB2/SiCw陶瓷在室温时只有长径比小于2.87的晶须在断裂时才有可能产生拔出,而在900℃时 相似文献
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H.J. Cheng 《Powder Technology》2010,199(3):272-175
The purpose of this study was to determine the effects of the properties of different binders on the granular agglomeration mechanism for the fabrication of pharmaceuticals. The raw materials included calcium carbonate powders with an average particle size of 32-75 μm and four different grades (4000, 6000, 8000 and 10,000) of polyethylene glycol (PEG) used as binders. The raw material was mixed with the binder in a high shear mixer. The surface structure of the granules was analyzed by low vacuum scanning electron microscope (LV-SEM) examination. Three major agglomeration mechanisms are discussed in this study: nucleation, consolidation and coalescence. The results showed that the agglomeration growth rate increased with increasing binder viscosity during the nucleation stage, but the exact opposite phenomenon occurred in the consolidation stage. Observation of the granular surfaces showed the surfaces to be full of fine powder in the nucleation stage, but PEG crystals appeared on the surface in the consolidation stage. During the coalescence stage, the granules grew quickly due to collisions and the surface structures of the granules became full of binders, as can be seen from the LV-SEM photographs. 相似文献
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3D打印技术作为一种快速成型技术,其采用数字式模型文件作为基础,采取逐层打印的办法将可粘合性的塑料或者粉末金属用以构筑所预想的实体技术.由于3D打印技术可采用的耗材种类不同,故其存在着不同的3D打印技术用于构造不同类型的部件.3D打印耗材常有尼龙玻纤、铝合金、钛合金、石膏、镀金银以及橡胶等材料.为了拓宽3D打印机所使用... 相似文献
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化工园区是化学工业的必不可少的载体,是由当地政府及企业组成的一个专业复杂系统,其运行中需要大量具有专业知识的领导干部、企业经营管理人才、专业技术专业人才及高级技能人才.这些人才作为化工园区发展的最重要资源,其引进机制、培育机制以及激励机制在本文进行了探索,认为化工园区专业人才的引进机制应注重岗位与人才相匹配,项目引进与人才建设并举,不断优化专业人才引进体系;化工园区专业人才的培育机制要坚持理论与实践培训相结合,采用“走出去,引进来”等多形式、开放性的人才培育体系,全面提升园区专业人才综合素养;化工园区的激励机制应坚持物质与精神激励相结合,不断提升专业人才的社会影响力,创造专业人才“扎根”化工园区的良好环境. 相似文献
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介绍"插套式"先复位机构的结构组成及其工作原理,并通过实例分析了这种先复位机构的具体应用。经生产验证,采用这种先复位机构可使注塑模具结构简单、紧凑,动作可靠,使用效果好。 相似文献
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《Journal of the European Ceramic Society》2022,42(15):7377-7380
In this paper, we solve the long-unsolved problem of whether β-Ta4AlC3 can be transformed from α-Ta4AlC3. By utilizing Ta, Al, and C as initial materials with molar ratios ranging from 4.0/1.2/2.6–4.0/2.0/2.6, it is shown that the synthesis of β-Ta4AlC3 is largely affected by the content of Al, and it is confirmed that α-Ta4AlC3 is stable at 1600 °C. Furthermore, by modifying the sintering temperature of the samples (4.0/1.2/2.6, 4.0/1.4/2.6, and 4.0/2.0/2.6) from 1450 °C to 1600 °C, the reaction paths of α-Ta4AlC3 and β-Ta4AlC3 are systematically investigated. It is determined that the β-Ta4AlC3 phase forms through the reaction among Ta2C, C, and Ta0.6Al0.4 and the reaction between Ta2AlC and TaC. For the α-Ta4AlC3 phase, there are also two reaction pathways: one from the reaction among Ta2C, C, and Ta0.6Al0.4, and the other from the combination among Ta3Al2C, Ta2C, C, and TaC. 相似文献
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《Ceramics International》2017,43(4):3679-3687
We have undertaken a systematic study of the effect of Fe3+ doping on the crystal structure, magnetic, electrical transport and magnetoresistance properties of La0.67Sr0.33Mn1−xFexO3 (0≤x≤0.15) polycrystalline coatings prepared by the sol-gel and screen printing method. The X-ray powder diffraction and Reitveld refinement results indicate that the partial substitution of Mn3+ ions by Fe3+ ions does not introduce noticeable lattice distortion and structural transition. Magnetic measurements show that Fe3+ ions significantly lowers the Curie temperature, and the magnetization at low temperatures first increases and then decreases with further Fe3+ doping. The Fe3+ doped manganites (x>0.05) are semiconductors with high resistivity, as the consequence of low number of available hopping sites of charge carriers. The most stimulating result obtained is that the magnetoresistance property is greatly enhanced around the percolation threshold (x=0.05) of Fe3+ ions in this system and the percolative phase separation is responsible for the anomalous behavior. 相似文献