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CHI Ru 'an LI Zhongjun PENG Cui ZHU Guocai XU Shengming 《稀有金属(英文版)》2005,24(3):205-209
1 IntroductionChinese rare earth resources are dominant in theworld with a total amount up to 80% of the wholeworld resources. Rare earth resources in China notonly have high grade and various types, but also dis-tribute reasonably. There are many rare ea… 相似文献
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采用熔炼法制备出新型高耐磨的Fe-20Ni-xMn-3.5C-2.5Si系固体自润滑材料,研究稀土元素Ce对Fe-20Ni-xMn-3.5C-2.5Si系合金中石墨的球化作用及Mn含量对力学性能及摩擦磨损性能的影响。结果表明:随着Mn含量的增加,合金凝固组织中奥氏体的硬度逐渐增大,特别是Fe-20Ni-xMn-3.5C-2.5Si-0.75Ce系合金在摩擦过程中的表面硬度大幅度提高,呈现出高锰钢特有的表面加工硬化性质,通过TEM可以观察到磨损表面生成孪晶型马氏体;添加0.75%(质量分数)的稀土Ce可以使结晶的石墨球化,使抗拉强度和抗弯强度大幅度提高,大约比未经球化处理的提高3~5.8倍;稀土Ce的加入可以促进Fe1.1Mn3.9C2型碳化物的生成,使材料的耐磨性进一步提高,其中Fe-20Ni-16Mn-3.5C-2.5Si-0.75Ce合金的磨损率最低,大约是QT500球墨铸铁的1/13。 相似文献
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采用X射线衍射仪、扫描电子显微镜、电池测试系统等研究了不同稀土掺杂元素La、Ce、Nd等对Pechini法合成的LiMn2O4材料的相结构、形貌及电化学性能的影响规律.结果表明,合成的LiMn2O4、LiLa0.03Mn1.97O4、LiLa0.01Ce0.01Nd0.01Mn1.97O4样品具有纯尖晶石型LiMn2O4结构,LiLa0.015Ce0.015Mn1.97O4样品由LiMn:O.相及微量杂质相CeO2组成;样品呈规则的近球形或球形,其粒径范围为0.5~2.5μm.稀土元素取代使LiMn2O4材料的初始容量略有降低、循环稳定性能有较大增加,LiMn2O4、LiLa0.03Mn1.97O4、LiLa0.015Ce0.015Mn1.97O4、LiLa0.01Ce0.01Nd0.01Mn1.97O42样品的初始容量分别为126.0、120.0、117.3、124.0 mA·h/g,经30次循环充放电后的容量分别为88.9、102.7、101.6、109.1 mA·h/g. 相似文献
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低扩渗效率和渗层孔隙是困扰着渗铬生产的两个重要难题。本文采用固体包埋法在GCr15表面制备渗Cr涂层,重点探讨了渗层的生长机制、孔隙成因及不同稀土氧化物的催渗作用。结果表明,加入稀土氧化物后渗层厚度明显提高,三种稀土氧化物的催渗效率依次为Y2O3>CeO2>La2O3。渗Cr层明显的分为双层结构,外层是以(Cr,Fe)23C6相为主的多孔层,内层为(Cr,Fe)7C3相为主的致密层。扩渗初期在基材表面首先生成的(Cr,Fe)23C6相层阻碍了表面活性Cr原子向内扩散,其自身作为Cr源向内扩散促进了致密层的生长,Cr原子扩散速度的差异及渗层中的应力是产生孔隙的主要原因。发现降低基体碳含量抑制(Cr,Fe)23C6相层的生成或细化该相层晶粒增加Cr原子扩散通道可有效降低孔隙率,这为改进渗铬层质量提供了一个重要思路。 相似文献
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用粉末法对20、45钢进行铝钛共渗,结果表明,采用双层密封比单层密封能获取更厚的渗层,此外,当以TiO_2为供钛剂时,AlF_3是适宜的活化剂,而以Ti粉为供钛剂时,NH_4F比AlF_3更好,在共渗剂中掺入稀土可使渗层厚度增加30%以上,稀土的催渗效果与扩渗温度和稀土掺入量等有关。 相似文献
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《稀有金属(英文版)》2017,(8)
Aluminum,the main impurity in the lixivium of weathered crust elution deposited rare earth ore,not only results in an increasing consumption of precipitant in the rare earth precipitation process,but also lowers the purity of final rare earth product.Aluminum in the weathered crust elution-deposited rare earth ore lixivium should be removed.Neutralizing hydrolysis method was employed to remove aluminum from the lixivium.Hexamethylenetetramine was found to be the optimum pH regulator for the removal of aluminum in the low concentration.When used to adjust the pH value of the lixivium to 5.0,aluminum in the lixivium can be effectively removed in the form of aluminum hydroxide precipitation with removal rate of 97.60%.It shows that hexamethylenetetramine has a good effect on the removing of aluminum ions from the lowconcentration lixivium.Moreover,hexamethylenetetramine in removing aluminum from lixivium has little adverse effect on the RE precipitation process. 相似文献
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Simultaneous recovery of rare earth, nickel and cobalt resources from the anode material of hydrogen-nickel battery was performed through a hydrometallurgical process. Most of rare earth elements are separated from nickel and cobalt in the form of sulfates when the anode material is firstly leached with sulfuric acid. Then, the precipitated rare earth sulfates are dissolved with sodium hydroxide to form rare earth hydroxides. The rare earth element, zinc and manganese ions in the lixivium are also separated from nickel and cobalt by using PC-88A extractant system, and the organic phase loaded rare earth is stripped with hydrochloric acid. By neutralizing the stripping solution with rare earth hydroxide, the rare earth chloride is obtained. Under the suitable leaching conditions of sulfuric acid 3 mol/L, leaching time 4 h and temperature 95 ℃, 94.5% of rare earth in the anode material is transformed into the sulfate precipitates, and the leaching ratios of nickel and cobalt can approach 99.5%. When the pH value of the extractive system is controlled in the range of 3.0-3.5, the rare earth elements in the lixivium can be extracted completely into the organic phase, and the stripping recovery of the rare earth can reach 98% in the extraction stage. The total recoveries of rare earth, nickel and cobalt are 98.9%, 98.4% and 98.5%, respectively. 相似文献
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1 IntroductionThestructureandelectrochemicalpropertiesofnickelhydroxidehavebeenstudiedextensivelyduetoitsimportanceasactivematerialsinnickelbatterysys tems[1 ].Afundamentalunderstandingoftheeffectsofmetallicadditivesandimpuri tiesonthenickelhydroxideelec… 相似文献
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为了开发和应用白云鄂博混合型稀土精矿的先进冶炼技术,采用Kissinger公式、TGA-DSC和XRD等分析方法,研究在氮气氛下白云鄂博混合型稀土精矿的热分解行为,包括热分解动力学、物相变化规律、铈氧化效率以及物相变化对稀土浸出率的影响。结果表明:在500~550℃焙烧时,焙烧质量损失率约10%、热分解活化能(Ea)为148 k J/mol。550℃焙烧2 h,白云鄂博混合型稀土精矿中氟碳铈矿完全分解,并转化为稀土氧化物和氟氧化物,铈氧化率最大值为0.58%。600℃焙烧2 h,稀土最大浸出率达49.1%。 相似文献
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Al 6013-20 SiC (p) in tempers T4, O, and F is sensitive to localized corrosion in 3.5 wt.% NaCl because of the preponderance
of the secondary phase particles of Cu, Fe, and Cr at the Al/SiC interface. Treatment with cerium chloride effectively inhibited
the localized corrosion of the alloy by suppressing the cathodic reactions at Al 6013/SiC interface as shown by electrochemical
investigations. Morphological studies showed the formation of a protective cerium oxide/hydroxide films, which suppresses
the corrosion of the alloy. 相似文献