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以Co、V、Cr的可溶性氯盐和草酸铵为原料,采用草酸盐共沉淀法制备Co、V、Cr的复合粉末的前驱体,热分解后获得Co-V-Cr复合粉末。通过DSC/TG分析对该前驱体在不同气氛(真空、氩气与氮气)中的热分解过程进行研究,通过扫描电镜观察与比表面积测试,对Co-V-Cr复合粉末的性质进行分析与表征。结果表明,不论在什么气氛下锻炼,所得Co-V-Cr复合粉末的粒径都达到纳米级,分散较均匀,V和Cr完全固溶在Co相中。前驱体合理的煅烧温度为450℃。在氩气气氛下前驱体粉末在421℃时直接分解成Co-V-Cr复合粉末;而在空气中的DSC-TG曲线在366℃出现放热峰,原因是此温度下发生氧化反应,前驱体先分解成Co-V-Cr然后被氧化。在氩气气氛下煅烧得到的Co-V-Cr复合粉末比表面积最大,为41.50 m2/g,粒径最小,平均晶粒尺寸为11~12 nm。 相似文献
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黄浦江两岸综合开发是上海市委、市府推进上海“四个中心”建设,增强城市综合竞争力的一项重大决策。根据《黄浦江两岸地区规划优化方案》,黄浦江两岸地区规划范围南起卢浦大桥,北至翔殷路——五洲大道,其范围涉及黄浦江两岸防汛墙,长度约为40km。规划按照“百年大计、世纪精品”的要求,通过沿江岸线功能的再开发以及滨江公共环境的建设,展示上海国际化大都市亲水、生态、历史文化和繁华的滨水新景观。 相似文献
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配置成分为WC-10%Co混合料,采用不同球料比(6:1与18:1)、不同球磨时间(4、8、16、32、48和72 h),以酒精为介质滚动球磨,干燥后压制成尺寸为6.5 mm×5.25mm×20 mm的试样,然后在H_2气氛下在1 340℃烧结,得到硬质合金试样,通过X射线衍射(XRD),扫描电子显微镜(SEM)等分别研究混合料中WC晶粒尺寸、内应变和晶格畸变等与球料比、球磨时间的关系。结果表明:(1)对于纳米级WC粉末,实验中的球磨过程不能破碎其晶粒;(2)随球磨时间延长,WC晶粒的内应变与晶格畸变呈先快后慢的增长方式,球料比越大,增速转折点越早出现;晶格的具体畸变形式与球料比相关;(3)在球料比6:1混合料中WC颗粒内发现"泊松效应";(4)在较低的内应变和WC邻接程度情况下,烧结早期WC晶粒合并长大所需的能量势垒较高,能够有效抑制WC晶粒早期长大。 相似文献
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本文针对绝经后女性骨质疏松具有以脊柱弥漫性疼痛和压痛、腰骶部疼痛为主要特征的特点,采用中西医结合的方法,即在运用西药治疗的同时,加服补肾壮骨类中药,共治60例,并设单纯西药治疗组45例对照.结果中西组痊愈率为63.3%,总有效率为96.7%.分析提示,中药在缓解疼痛症状,巩固和加强治疗效果、同时缓解其他药物的毒副作用方面,具有明显的优势.因此,对已有症状的老年妇女在合理摄入营养、适当增加运动的同时,采用中西医结合方法治疗,确为一种比较有效的可取的方法. 相似文献
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The separation method of changeable valence RE element of cerium(Ce) was reviewed in this paper. Solvent extraction is the most effective and efficient method to separate Ce(IV) from RE(Ⅲ), usually accompanied with fluorine(F) and phosphor(P) from bastnaesite and monazite etc. By roast or wet-air oxidation, Ce(Ⅲ) of bastnaesite and monazite was oxidized into Ce(IV), and Cyanex923 and [A336][P507] have been investigated to co-extract and recover Ce(IV), F and P from H2SO4 leaching liquor, leading to favorable conditions for the subsequent separation of Th(IV) and RE(Ⅲ). The interaction of Ce(IV) and F and/or P enhances the roasting, leaching and extraction of Ce(IV) due to increasing of the stability of Ce(IV), and the formation of CeF3 and CePO4 after reductive stripping will benefit the utilization of F and P. For dealing with RE ores of high-content Ce, the clean process of oxidation roasting and Ce(IV)-F separation for Sichuan bastnaesite highlights the advantages of Ce(IV) based clean technique, which firstly demonstrates the comprehensive utilization of Ce(IV), Th(IV), F and RE(Ⅲ) and prevention of environmental pollution from fountainhead. A preliminary flowsheet of two-step oxidation and extraction of Ce(IV) for Bayan Obo mixed ores was further proposed to process the oxidation and extraction of Ce(IV) in presence of both F and P, indicating the possibility of similar effects with clean process of Sichuan bastnaesite. Ce(IV) separation chemistry and clean technique will open up new realms for light RE resources utilization, meeting "Emission Standards of Pollutants from Rare Earths Industry" promulgated by China's Ministry of Environment Protection(MOP) in 2011. 相似文献
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