共查询到19条相似文献,搜索用时 93 毫秒
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论述由硅酸钠和硫酸制备适用于牙膏及透明牙膏的二氧化硅,所得产品含二氧化硅w(SiO2)≥92.0%,结构水w(H2O)为3.5%-4.5%;pH值6.2-7.0。粒径6-12μm。松密度200-300g/L。吸油值90-150ml/100g,辐射牙本质磨损(RDA)值5070,折光率1.400-1.445。 相似文献
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以硅酸钠和硫酸为原料,采用沉淀法工艺,控制釜底液碱浓度0.2~0.3moL/L、反应温度80-95℃、反应时间30-90min、反应pH8-10、熟化时间10-30min,助剂质量浓度15-30g/L,合成透明牙膏组合物用二氧化硅摩擦剂。着重考察了釜底液碱浓度、助剂质量浓度等对二氧化硅性能的影响。此种二氧化硅摩擦剂的比表面积为30-54m^2/g,邻苯二甲酸二丁酯(DBP)吸收值为0.9-1.4mL/g,平均粒径为6~10μm,辐射牙釉质磨损(RDA)值低于150,pH为6-7,水分质量分数为3%-5%。此种二氧化硅引入到透明牙膏中,体系透光率为40%-85%。 相似文献
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采用NP-5/环己烷/去离子水体系制备反相微乳液,绘制了该体系的三元相图,并以正硅酸乙酯(TEOS)为原料,在碱性条件下受控水解反应制备了纳米SiO2粒子,探讨了[n(水)∶n(表面活性剂)](用R表示)和[n(水)∶n(TEOS)](用H表示)对SiO2纳米粒子粒径的影响。通过扫描电镜(SEM)和激光粒度仪对样品形貌和粒子大小和粒径分布进行了表征。结果显示:扫描电镜下观察到的SiO2粒子为无定型球形颗粒,粒径在200~500 nm的范围,激光粒度仪分析得到的平均粒径随着R和H的增大而增大。 相似文献
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Hydrothermal Treatment of a Silica Sand Complex with Lime 总被引:1,自引:0,他引:1
Osamu Watanabe Kazuko Kitamura Hiroki Maenami Hideki Ishida 《Journal of the American Ceramic Society》2001,84(10):2318-2322
The feasibility of using relatively low-purity silica as the starting material for hydrothermal solidification was investigated from the consideration of effective utilization of natural resources. Hydrothermal solidification was performed at 140°–180°C for periods ranging from 2 to 40 h using a mixture of 80% silica sand (containing 67% quartz, 22% clay minerals (mica, clinochlore, and kaolinite), and 7% feldspar) and 20% Ca(OH)2 . Within the range of experimental conditions, the flexural strength of the solidified bodies increased with increased treatment temperature and treatment time, reaching values of up to 20 MPa. The flexural strength was proportional to the amount of, but independent of the type of, reaction products. Hydrogarnet and C-S-H were formed in the initial stages of the reaction; the amount of these phases tended to decrease, and 1.1 nm tobermorite formed as the reaction further progressed. These results indicated that hydrogarnet and C-S-H were precursors of 1.1 nm tobermorite. 相似文献
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硅橡胶用白炭黑的制备 总被引:1,自引:1,他引:0
以浓硫酸为原料合成硅橡胶用白炭黑,研究了反应温度和反应时间对白炭黑吸油值、堆积密度、和中位径的影响.研究发现:随着反应时间的延长吸油值先增大后减小,堆积密度先减小后增大,中位径先减小后增大.随着反应温度的提高,吸油值先增大后减小,堆积密度先减小后增大,中位径逐渐减小.通过对这些实验因素进行综合分析优化,确定最佳反应温度为85 ℃,反应时间为25 min,制备了适合硅橡胶补强用的白炭黑. 相似文献
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用不同pH值下的硅酸钠溶液涂覆碳化硅,得到二氧化硅陶瓷涂覆的碳化硅颗粒,用光学显微镜分析了碳化硅颗粒表面的形貌,测定了不同条件下合成的碳化硅亲水性,并对比了纯碳化硅和改性碳化硅对酚醛树脂的润湿性。结果表明,陶瓷液pH=10时所得的碳化硅颗粒陶瓷涂层最为均匀,陶瓷涂覆的碳化硅颗粒的亲水性最好,碳化硅与酚醛树脂的润湿性不如改性的碳化硅颗粒的好。 相似文献
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Jacques Jupille Anne-Marie Flank Pierre Lagarde 《Journal of the American Ceramic Society》2002,85(5):1041-1046
The local structure centered on sodium after diffusion in silica (Na-SiO2 samples) has been determined by means of extended X-ray absorption fine structure (EXAFS) studies. The Na-SiO2 samples are of particular interest because (i) their sodium content can be varied over a wide range of concentration and (ii) their local structure is representative of that of soda–silica glass. EXAFS analyses reveal the existence of a well-defined local structure involving oxygen, sodium, and silicon neighbors. The Na-O, Na-Na, and Na-Si bonds lengths, which amount to 0.23, 0.30, and 0.38 nm, respectively, do not depend on sodium concentration. This environment closely resembles that found in soda–silica glass. Moreover, it is compatible with the "target site" and "the site memory effect" suggested by recent theories of the ionic conductivity in oxide glasses. 相似文献