共查询到19条相似文献,搜索用时 203 毫秒
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铈盐对铝合金硼酸?硫酸阳极氧化膜的封闭效应 总被引:2,自引:0,他引:2
将铝合金硼酸-硫酸阳极氧化膜浸入铈盐转化液中进行封闭。采用交流阻抗谱技术研究各封闭参数对氧化膜耐蚀性的影响,比较了不同方法封闭的氧化膜的耐蚀性差异。结果表明:将硼酸-硫酸阳极氧化试样浸入30℃的铈盐转化液(5 g/L Ce(NO3)3+0.5%H2O2)中处理30 min后,多孔层电阻Rp大幅增加,且腐蚀电流密度降低1个数量级,耐蚀性明显优于沸水封闭氧化膜的,也稍优于稀铬酸封闭氧化膜的耐蚀性。结合EDS分析表明:铈盐转化封闭后硼酸-硫酸阳极氧化膜的外表面形成了一层完整致密的铈盐转化膜,多孔层内也充满了铈的封闭产物,二者的协同作用几乎完全封住了硼酸-硫酸阳极氧化膜的孔隙,从而有效地提高了氧化膜的耐蚀性。 相似文献
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《中国有色金属学会会刊》2017,(3)
研究了铈盐缓蚀剂对2024-T3铝合金阳极氧化的影响。采用带X射线能谱仪的扫描电子显微镜分析合金表面处理前后的表面组分。使用含0.1 mol/L硫酸铈盐的混合电解液作为阳极氧化电解液,该混合电解液由10%硫酸、5%硼酸和2%磷酸组成。在沸水和溶化的硬脂酸中进行密封处理,分别利用电化学交流阻抗和盐雾技术研究氧化膜的腐蚀行为和耐用性。结果表明,阳极氧化电解液中存在的铈离子导致合金更均匀,氧化膜生长率提高和氧化层的厚度增加,这些都是因为铈离子具有高的氧化能力。 相似文献
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研究了Al6061/SiCp复合材料阳极氧化稀土盐封孔工艺,利用电化学方法评价了化膜的耐磨蚀性能,稀土盐封孔氧化膜的耐蚀性与铬酸封闭是极氧化膜具有可比性。利用X射线衍射分析(XRD)了氧化膜的结构,结果表明氧化膜为非晶态。X射线光电子能谱(XPS)分析证明氧化膜表面的主要成分是铈的氢氧化物。 相似文献
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镁合金表面稀土铈盐转化膜的制备与耐蚀性能 总被引:1,自引:1,他引:0
目的在镁合金表面制备稀土铈盐转化膜,以改善镁合金的耐蚀性能。方法利用化学转化技术在镁合金表面制备出稀土铈盐转化膜,进而采用SEM、EDAX及电化学测试技术等系统研究铈盐浓度、添加剂含量、转化时间和转化温度对转化膜形貌、成分和耐蚀性能的影响。结果稀土铈盐转化膜呈金黄色,由Mg、Ce和O组成,表面存在网状裂纹。转化膜的耐蚀性随铈盐浓度、添加剂含量、转化温度、转化时间的增加呈现先增加后降低的变化规律。结论稀土铈盐转化膜由Mg和Ce的氢氧化物和氧化物组成。铈盐转化膜的最佳工艺条件为:Ce(NO3)3质量浓度10~15 g/L,H2O2添加含量25~50 m L/L,转化温度40℃,转化时间30 min。经稀土铈盐转化处理后,镁合金的耐蚀性能得到了明显的改善。 相似文献
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采用激光共聚焦显微镜、场发射扫描电镜(SEM)和电子背散射衍射(EBSD)等设备,对含稀土Ce的耐热钢253MA连铸坯的凝固组织及夹杂物的形貌、成分和结构进行表征分析。结果表明:比较两种含稀土Ce耐热钢的凝固组织,稀土Ce有增大凝固组织等轴晶率、细化柱状晶的作用;稀土Ce夹杂物主要相结构为CeO2和(CeO)2SO4,呈细小、近球形弥散分布;对夹杂物进行统计和评级,发现稀土Ce含量的增加有利于D类球形夹杂物增多,有助于提高耐热钢的耐高温、抗氧化性能。 相似文献
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The effect of rare earth elements Ce and La on the evolution behavior of inclusions in HRB400E steel was studied through experimental observations and thermodynamic calculations. Neutral salt spray corrosion experiments were also conducted to investigate the effect of Ce–La on the corrosion resistance of steel. The results showed that the typical inclusions in steel without rare earth were MnS and MnO–SiO2. A small amount of Mn–Si–O–S inclusions was also observed. After adding rare earth, the typical inclusions were transformed into isolated (Ce,La)2O2S, (Ce,La)2O3 + MnS, and (Ce,La)2O2S + MnS complex inclusions. The thermodynamic calculations indicated that the rare earth elements in molten steel preferentially reacted with MnO–SiO2 inclusions and dissolved oxygen and sulfur to form (Ce,La)2O3 and (Ce,La)2O2S. Small amounts of [S] and [Mn] adhered to the surface of the nucleated rare earth inclusions to form complex inclusions. After Ce–La treatment, the corrosion rate of the steel decreased from 3.491 to 1.992 mm year−1, and the corrosion resistance was improved. The change in corrosion behavior is due to the modification of the inclusions into rare earth inclusions with good compatibility with the steel matrix. 相似文献
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研究了不完全脱水氯化镁与稀土氯盐混合在电解槽中直接电解生产镁铈合金的新方法,所用电解质为非氟化物电解质,电解温度低,不改变目前工业镁电解槽的槽型,易于工业推广应用。研究的目的是使我国在用青海盐湖水氯镁石为原料电解镁的研究中取得突破性进展,以此推动利用青海盐湖镁资源取得巨大进展,并结合青海、甘肃周边丰富的稀土资源,制备镁稀土合金。实验过程采用不完全脱水氯化镁为电解原料,简化了工艺步骤,还可以有效利用提取镨、钕后大量剩余的铈稀土,使稀土元素铈可以得到广泛应用,将产生很好的经济效益。 相似文献
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YAN Kai ZHEN Qiang Song Xiwen 《稀有金属(英文版)》2007,26(4):311-316
Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the SmzO3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Srno.2oCe0.8Ol.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the An'henius equation. Then the SmzO3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index. 相似文献
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通过PCT(Pressure-Content-Temperature)设备研究了催化剂CeCl3和Ce(SO4)2对NaAlH4可逆储氢性能的影响.结果显示试样总放氢量随着CeCl3和Ce(SO4)2含量的增加呈先增加后降低的趋势.在第一放氢阶段,掺杂4 mol% CeCl3试样的放氢速率和放氢量都优于掺杂3 mol% Ce(SO4)2的试样.在110,130,150和180℃条件下,试样的放氢速率和放氢量随着温度的升高明显升高. 相似文献
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采用稀土盐CeCl3为添加剂,通过调整镀液中CeCl3浓度在20#钢基体上电沉积制备Ni-Fe合金镀层.采用SEM,EDS和XRD等表征镀层的结构,采用电化学极化曲线和阻抗谱研究合金镀层在3.5%(质量分数)NaCl溶液中的耐蚀行为.结果表明:稀土添加剂在低pH值酸性体系中极易生成Ce(OH)3溶胶,抑制 (FeOH) 和Fe(OH)2等化合物的生成,其阴极吸附特性与 (FeOH) 的吸附形成竞争,优先吸附于材料表面,从而抑制了Fe的析出;另一方面CeCl3的加入大大提高了电流效率,使镀速增大.当CeCl3的浓度为3 g/L时,镀层中Fe的含量控制在16%左右,获得较好的镀层质量及较好的耐蚀性能. 相似文献
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采用球磨的方式在LiAlH4中分别掺入3种稀土催化剂LaCl3、CeCl3和Ce(SO4)2,研究了稀土催化剂对LiAlH4的相结构和放氢性能的影响。结果表明,在球磨过程中,掺杂Ce(SO4)2对LiAlH4的分解基本没有影响,而掺杂LaCl3和CeCl3则造成LiAlH4部分分解,产生了LiCl和Al3RE(RE=La,Ce)相。在LiAlH4放氢反应中,稀土催化剂的加入均使LiAlH4初始放氢温度降低,特别是Ce(SO4)2使第1步的放氢温度降低了约25 ℃。稀土催化剂有助于加快LiAlH4分解反应速率,提高LiAlH4的放氢性能。 相似文献
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The effects of rare earth elements on the corrosion properties of low-carbon steel and weathering steel were investigated. To elucidate the roles of rare earth elements (Ce and La) and the corrosion behavior of steels, salt spray tests, electrochemical techniques, X-ray diffractometer, scanning electron microscopy, Electron Probe Micro Analysis (EPMA), and Auger Electron Spectroscopy (AES) were conducted. The results showed that the addition of rare earth elements enhances the corrosion resistance of both low-carbon steels and weathering steels, indicated by lower corrosion current density and salt spray corrosion rate after rare earth alloying. On the one hand, rare earth elements modify the morphology of inclusions and thus slow down the micro-area electrochemical corrosion, which improves the electrochemical corrosion resistance of these two steels. On the other hand, rare earth atoms tend to segregate toward the interface between the rust layer and the matrix. Hence, salt spray corrosion resistance is improved due to the enhancement of adhesion and compactness of the rust by the addition of rare earth elements. 相似文献