共查询到19条相似文献,搜索用时 125 毫秒
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由于树脂自硬砂具有流动性好、强度高、高温收缩小、溃散性好等优点,近些年来树脂自硬砂造型制芯迅速发展.尤其在日本等工业发达国家,中型铸件过去用粘土砂干型的,现在几乎全部改用树脂自硬砂,用水玻璃、水泥等其它类型自硬砂的也较多地改用树脂自硬砂.我国的树脂自硬砂初期发展较慢,但近些年发展较快,取得了相当的成就.树脂自硬砂的使用涉及到原砂、树脂和硬化剂、工艺控制及再生等.文中重点对树脂自硬砂用原砂种类、原砂的处理和原砂质量对树脂自硬砂性能的影响作出综述,供铸造工作者参考. 相似文献
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研究热固性树脂固化的动态扭振法──LHX-I型树脂固化仪在热固性树脂和树脂基复合材料固化研究中的应用 总被引:1,自引:0,他引:1
LHX-I型树脂固化仪能快速定量跟踪热固性树脂和树脂基复合材料在实际成形中的固化过程,是确定热固性树脂、粘合剂、聚氨酯液态橡胶、树脂基复合材料和互穿网络聚合物的配方筛选,最佳固化工艺条件的选择以及生产质量控制和监测的有效工具,也为固化反应表观动力学的研究提供了又一个动态力学方法。 相似文献
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研究热固性树脂固化的动态扭振法:——LHX—Ⅰ型树脂固化仪在热固性树脂和树 总被引:5,自引:0,他引:5
LHX-Ⅰ型树脂固化仪能快速定量跟踪热固性树脂和树脂基复合材料在实际成形中的固化过程,是确定热固性树脂,粘合剂、聚氨酯液态橡胶、树脂基复合材料和互穿网络聚合物的配方筛选,最佳固化工艺条件的选择以及生产质量和监测的有效工具,也为固化反应表观动力学的研究提供了又一个动态力学方法。 相似文献
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一、国内消费走向及对本行业的影响按照近几年的统计数据,国产树指和进口树脂的比例大体为1∶1.35。进口树脂的年增长率除了近一二年外,均略高于国产树脂的年增长率。将进口树脂与国产树脂合一,树脂的市场消费结构大致为:聚乙烯占30%以上,聚丙烯占20%~24%,聚氯乙烯约20%,聚苯乙烯10%~12%,ABS占7%左右,其他树脂占8%~9%。除了传统的农业用塑料制品之外,由于国家宏观调控的作用,使包装行业、建筑工业、汽车工业、家电行业和电子电器等行业得以快速发展。今后几年塑料制品的大致走向为:①涉及农业和包装两大行业的膜… 相似文献
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A new class of antifriction polymer composite materials, i.e. carbon plastics, is considered in terms of their application in machine building. They exceed traditional antifriction polymer materials in their characteristics. The use of sliding bearings made of carbon plastics in ship and energy machine building has shown their high efficiency. 相似文献
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The effects of epoxy resin formulation on tissue contrast and organelle size were evaluated by examining thin sections of rat liver in the electron microscope and by doing a simple morphometric analysis of peroxisome and nuclear size. Contrast was greatest for tissues embedded in the Quetol formulation of Kushida and least for tissues embedded in the Ladd formulation. Epon 812, Epon-Araldite, and Spurr formulations gave results intermediate to those of the Quetol and Ladd formulations. Organelle size was greatest for tissues embedded in the Ladd formulation and smallest for tissues embedded in the Spurr formulation. The maximum size differences were approximately 15%. Epon 812, Epon-Araldite, and Quetol formulations gave results (for organelle size) intermediate to those of the Ladd and Spurr formulations. The gross shrinkage properties of the epoxy resin blocks were all the same and, therefore, could not account for the differences in organelle size. 相似文献
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SiO_2纳米复合材料的研究 总被引:5,自引:0,他引:5
以纳米 Si O2 作为增强材料 ,制备纳米复合材料 ,研究了不同处理方法及不同的纳米 Si O2 含量对纳米复合材料性能的影响 ,采用透射电镜对纳米 Si O2 粒子的分布进行了表征。结果表明 ,超声波与均质高速分散机结合使用 ,可以使纳米 Si O2 粒子均匀分散于环氧树脂基体树脂中。当纳米粒子 Si O2 含量为 3%时 ,复合材料的性能最佳 相似文献
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Jos C. Meurer Fabio A. P. Rizzante Rafael M. Maenossono Fabiana M. G. Frana Juliana F. S. Bombonatti Srgio K. Ishikiriama 《Microscopy research and technique》2020,83(3):304-309
The quality of the micromechanical retention between the enamel prisms exposed through acid etching and adhesive system can be influenced by the relationship between the angle of the exposed enamel prisms and the external surface/restorative material. Therefore, the aim of the present study was to determine the influence of the enamel cavosurface beveling in different cavity sizes on the angle relation between enamel prisms and the restorative material. For this research, 30 human permanent molars were used and divided into three groups according the isthmus aperture of class I cavities (1/4, 1/3, and 1/2 of the intercuspal distance). Cavosurface angle beveling was performed in each tooth buccal or palatal/lingual side, and a resin composite restoration was placed. Each restored tooth was sectioned in buccal/palatal direction followed by analysis in scanning electron microscope. Means of the angles observed between enamel prisms and the restorative material were registered and statistically analyzed by Kruskal‐Wallis test. Results showed higher mean angle values for beveled groups when comparing with the values observed in the unbeveled margins (p < .05) regardless of the isthmus aperture, being 1/4 (beveled = 48.36°; unbeveled = 20.71°), 1/3 (beveled = 39.75°; unbeveled = 29.15°), and 1/2 (beveled = 37.02°; unbeveled = 26.34°). It was also observed that in some unbeveled cavities, there were the presence of laterally exposed enamel prisms (0°), mainly in more conservative cavities. It was concluded that the presence of higher angles values occurred in the samples with beveled margins, without presence of laterally exposed enamel prisms. 相似文献