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为获得具有良好使用性能的碳化硅基陶瓷复合材料,以亚微米级Si C粉体和分析纯的Al(NO_3)_3与Y(NO_3)_3为主要实验原料、氨水为沉淀剂,用共沉淀包覆方法制备Si C-Al_2O_3-Y_2_O3纳米复合粉体,对复合粉体前驱体的DTA进行分析,并研究其在煅烧过程中的物相变化,以及煅烧温度对复合粉体的分散性和烧结性的影响。结果表明:Al_2O_3和Y_2O_3反应生成新相YAG,当YAG质量分数为10%、煅烧温度为600℃,复合粉体的烧结性能最好。 相似文献
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郁山-礼庄寨地区处于华北陆块南部,隶属陕县-渑池-新安主要富铝(黏)土矿成矿带东段,是河南省最为重要的优质铝土矿成矿区。分别采用重力测量、可控源音频大地电磁法测量(Controlled source audio-frequency magnetotelluric method,CSAMT)、瞬变电磁测量(Transient electromagnetic measurement,TEM)、地震测量和地面高精度磁法测量在研究区进行了铝土矿深部找矿试验。结果表明:重力测量对于圈定大地构造效果显著,铝土矿床一般分布于重力高与重力低渐变过度带上;CSAMT法能反映奥陶系灰岩层面的起伏变化,可以准确判断铝土矿隐伏空间的分布状态。根据试验结果,优选重力测量和CSAMT法进行综合成矿预测,采用重力测量确定铝土矿成矿有利区,利用CSAMT法在成矿有利区准确判断隐伏灰岩侵蚀面起伏情况,推测铝土矿隐伏空间特征。综合成矿预测结果表明:①研究区铝土矿多分布于靠近古隆起边缘的凹陷区范围内,铝土矿床产于下古生界奥陶系碳酸盐岩不整合面上,严格受喀斯特地貌控制,侵蚀面上形成大小不等的洼地及溶斗是铝土矿的定位空间;②提交了渑池礼庄寨北、候岭2个大型铝土矿产地和礼庄寨深部找矿靶区1处,其中,礼庄寨北矿产地发现铝土矿矿体3条,提交资源量5 683.02万t;候岭矿产地发现矿体2条,提交资源量9 567.35万t;预测礼庄寨深部找矿靶区矿体埋深300~700 m,有较好的找矿远景;③河南省铝土矿深部成矿预测物探工作方法为重力扫面-CSAMT测量,利用重力扫面确定铝土矿成矿有利区,采用CSAMT剖面测量确定铝土矿隐伏空间特征。 相似文献
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Electrochemical deposition of aluminum on W electrode from AlCl3-NaCl melts was studied by cyclic voltammetry and chronopotentiometry. The results show that Al ( Ⅲ) is reduced in two consecutive steps, i.e., 4Al2Cl7-+3e-→Al+7AlCl4- and then AlCl4-+3e-→Al+4Cl-. The electrochemical reaction of 4Al2Cl7-+3e-→Al+7AlCl4- is reversible. Certain nucleation overpotential is required during the deposition of aluminum on W electrode. Chronopotentiometry analysis also shows that Al (Ⅲ ) is reduced in two consecutive steps under certain current density, which is in reasonable agreement with cyclic voltammograms. By using constant current deposition, the electrodeposits on Al substrate obtained at between 50 and 100 mA/cm2 are quite dense and well adherent to the Al substrate. The electrochemical deposition of aluminum on Cu substrate in AlCl3-NaCl melts indicates that the intermetallic compounds are formed. The intermetallic compounds are AlCu and Al2Cu. 相似文献
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Electrical conductivity of NaF-AlF3 melts was measured by continuously varying cell constant(CVCC) technique. Relationships between equivalent conductivity at 990-1 030 ℃ and temperature and composition, and relationship between equivalent conductivity activation energy and composition of the melts were then studied on the basis of two-step decomposition mechanism of AlF63-. According to the changes of molar fractions of different anions in NaF-AlF3 melts, courses of dependence of equivalent conductivity and its activation energy on composition were analyzed. The results show that the influence of temperature on equivalent conductivity of the melts is small in the researched temperature range, and equivalent conductivity increases with increasing the molar fraction of AlF3; there is a minimum point in the activation energy-composition curve when molar fraction of AlF3 is 0.29. 相似文献