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排序方式: 共有1672条查询结果,搜索用时 55 毫秒
1.
Zirconium(IV) tungstoiodophosphate has been synthesized under a variety of conditions. The most chemically and thermally stable
sample is prepared by adding a mixture of aqueous solutions of 0·5 mol L−1 sodium tungstate, potassium iodate and 1 mol L−1 orthophosphoric acid to aqueous solution of 0·1 mol L−1 zirconium(IV) oxychloride. Its ion exchange capacity for Na+ and K+ was found to be 2·20 and 2·35 meq g−1 dry exchanger, respectively. The material has been characterized on the basis of chemical composition, pH titration, Fourier
transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The effect on the exchange capacity of drying the exchanger
at different temperatures has been studied. The analytical importance of the material has been established by quantitative
separation of Pb2+ from other metal ions. 相似文献
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用激光粒度分析仪测定二氧化锆粒度 总被引:3,自引:0,他引:3
介绍以六偏磷酸钠作为分散剂,采用激光粒度分析仪测量二氧化锆粒度的一种新方法。该方法的测量范围为0.05~300μm。 相似文献
5.
用共沉淀法制备了TiO2-ZrO2复合氧化物载体,BET,DTA,XRD表征结果表明,该复合载体具有较大的比表面和较好的热稳定性,对于环己酮肟气相Beckmann重排反应制己内酰胺,用复合载体制备的B2O3/TiO2-ZrO2催化剂,比分别以TiO2,ZrO2为载体所制备的B2O3/TiO2和B2O3/ZrO2催化剂具有更高的活性和选择性,实验表明,催化剂表面中等强度的酸位是环己酮肟气相Beckmann重排反应的有效活性中心。 相似文献
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Charles A. Barrett 《Oxidation of Metals》1988,30(5-6):361-390
The effect of 0.1 at.% Zr (0.2 wt.% Zr) on the cyclic oxidation of hipped -NiAl was studied. Oxidation testing was performed in static air at 1100–1200 °C, using 1-hr exposure cycles for test times up to 3000 hr. The weight change versus time data were modeled with the COSP computer program to analyze and predict cyclic-oxidation behavior. Zr additions significantly change the nature of the scale-spalling process during cooling so that the oxide spalls near the oxide-air interface at a relatively low depth within the scale. Without Zr, the predominantly -Al2O3 scale tends to spall randomly to bare metal at relatively high effective-scale-loss rates, particularly at 1150°C and 1200°C. This leads to higher rates of Al consumption for the Zr-free aluminide and much earlier depletion of Al, leading to eventual breakaway (i.e., failure). 相似文献
9.
A. F. Y. Al-Shammary I. T. Caga A. Y. Tata J. M. Winterbottom I. R. Harris 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,55(4):361-367
Alloys of the general formula Zr50NixCO50-x, where 0 ≦x≧ 50, have been prepared and used in the temperature range 300–400°C, in the pressure range 1–9 barg in a microtubular reactor for the reaction of hydrogen with carbon monoxide to give hydrocarbons. The alloys or intermetallic materials were prepared by argon arc melting, powdered by hydrogen decrepitation and characterised by means of optical microscopy (metallography), scanning electron microscopy with surface analysis and magnetic susceptibility measurements. The selectivity towards higher hydrocarbons increased with (i) increase in the total pressure and (ii) decrease in hydrogen content of the feed gases. The kinetics were found to be of the form: where m = 1.0 ± 0.2 and n = 0. The apparent energy of activation (Ea) lay in the range of 80–130 kJ mole?1 and there appeared to be a compensation effect between Ea and the pre-exponential factor A. The turnover numbers for the reaction exhibited an activity maximum for alloys of composition around Zr50Ni40Co20 and Zr50Ni30Co20. Magnetic susceptibility measurements indicated that alloys changed their nature from moderately paramagnetic to strongly paramagnetic or even ferromagnetic after use and this is attributed to the conversion of zirconium to zirconium oxide during reaction with the attendant production of free 3d-transition metals. Derived catalysts prepared by air treatment of the hydrogen-decrepitated intermetallics behaved almost identically to the latter materials and gave similar magnetic susceptibility values to used hydrided materials. 相似文献
10.
我国锆英砂矿的放射性分析 总被引:2,自引:1,他引:2
调查分析了我国3个典型矿区锆英砂堆放表面γ剂量、放射性比活度、铀系和钍系平衡状况以及放射性元素含量;测定了我国海南万宁矿区锆英砂的组成及放射性。结果表明:①我国矿区锆英砂的放射性比活度比澳大利亚的锆英砂高了一个数量级,澳大利亚的锆英砂基本上是符合工业使用要求;②我国山东荣城锆英砂的放射性比活度与澳大利亚锆英砂的放射性比活度接近,但是其中铍的含量很高,不适于用做化工原料;③锆本身不具有放射性,锆英砂的放射性主要是由于锆英砂中存在的独居石等含有少量的铀、钍和镭,使得锆英砂具有了放射性。 相似文献