Palladium-rare-earth metal alloys-advanced materials for hydrogen power engineering

Hydrogen of no less than 99. 999 , (vol. fraction) purity is a principal power media of hydrogen power engineering. A single method for the preparation of high purity hydrogen consists in its separation from vapour-gas mixtures via the selective diffusion of hydrogen through a palladium membrane. The rate of hydrogen diffusion and the strength and stability during the operation in aggressive gases are important characteristics of palladium membranes. The increase in the strength, plasticity, and hydrogen-permeability of membrane alloys can be reached by alloying palladium with the formation of solid solutions.The formation of wide ranges of palladium-rare-earth metal (REM) solid solutions is an interesting feature of palladium. Earlier, we have shown that the alloying of Pd with REM substantially increases the rate of hydrogen diffusion and markedly increases the strength of palladium on retention of the adequate plasticity.In this work, we have studied alloys of the Pd-Y and Pd-Y-Me systems. It was shown that the following conditions should be satisfied to prepare high-quality alloys exhibiting high service properties: (1)the use of high-purity components (whose purity is no less than 99.95,, mass fraction), in particular,high-purity Y prepared by vacuum distillation, and (2) holding the reached purity for the final product.For this purpose, we suggested a cycle of manufacturing operations including the preparation of a vacuumtight foil of 50 (m thick as the final stage.The hydrogen-permeability of the alloys was measured at different temperatures and hydrogen pressures. The instability of operation of binary Pd-Y alloys w alloying the composition with a Ⅷ Group metal. For example, the alloy of the optimum composition Pd-8Y-Me in the annealed state exhibits the following mechanical properties: HV= 75 kg/mm2 , σu = 58 kg/mm2 , and δ= 20,. Its hydrogen-permeability (QH2) measured as a function of the temperature exceeds that of the Pd-23Ag alloy (that is widely used by foreign companies) by a factor of 1.5-2; it is 3.6-4.7 m3/m2 hMPa0.5 at 300-600℃, respectively.The alloys exhibiting the high hydrogen-permeability combined with the high mechanical properties shows promise as materials for diffusion hydrogen purification devices whose productivity reaches tens thousands nm3/h.     

Some special features of formation of manyfunctional powders steels structure

It has been studied connection between composition, structure and properties of powder steels using technology of their own. Nitrogen containing powders were obtained by mechanical allowing (MA) of Fe-Cr and Fe Cr Ni-C mixtures in a high-energy planetary mill in the gaseous nitrogen environment. The contents of nitrogen after MA was 0. 7 , in Fe-Cr-N and 2.1, in Fe-Cr-Ni-C-N mixes. Phase composition after the mechanical alloying was: in system Fe-Cr-N - solid solution of chrome in iron and α - Fe, in system Fe-Cr-Ni-C-N-40, γ-phase (vol. fraction) , α - Fe and solid solution Cr-Fe.There are investigated physical-mechanical, tribo-technical and specify properties of the nitrous steels,are fixed the base dependences between parameters of process of MA and structure of steels. Introduction of nitrogen by rather new method of MA, as against saturation of melts, allows to run phase composition - to generate structure with more dispersible and uniform nitrides or with the nitrous austenite (depending on purpose of steel).It is demonstrated by means of X-ray diffraction and method of Raman spectrum analysis, that in a sintering process of powder steels, obtained by introduction of carbon in the form of cast-iron powder, a formation of metallofullerite phase Fex C60 at determined conditions. The possibility of fullerenes conception in powder carbon steels, diffusion of iron atoms at fullerite lattice and formation of metallofullerites during contact interaction of fullerene with iron is confirmed experimentally.Dependence of synthesis activity of fullerences from temperature of sintering, type and quantity of alloy elements is determined.     

机械合金化LaNi5-26wt%Mg合金的结构及性能研究

采用X -射线衍射仪 (XRD)、扫描电子显微镜 (SEM)、差热分析仪 (DTA)及电池性能测试仪等研究了机械合金化及热处理等工艺因素对LaNi5 2 6wt%Mg合金的组织形貌、热稳定性及电化学贮氢性能等的影响。结果表明 :经 2 80r/min机械合金化 2 5 0h后 ,样品由镧、镁、镍等非晶和MgNi2 纳米晶(3 1nm)组成 ,颗粒形状为规则的球形或近球形 ,粒径为 0 0 6～ 12 6μm ,其中约有 95 %的颗粒的粒径为0 5～ 2 0 μm。该样品经首次充放电活化时即达到其最大的放电容量 (4 2 0mAh/g) ,具有较好的室温电化学活化特性。经 763K保温 3 5d ,样品由热稳定性较好的具有纳米尺度 (2 4 1nm)的Mg2 NiLa、Mg2 Ni、MgNi2 三相组成。     

Alloying Behaviour of Cu, Mg and Mn in Lead-free Al-Cu Based Alloys Intended for Free Machining

Due to current EU guidelines, the production of aluminium machining alloys with lead contents exceeding 0.4 wt.-% has been prohibited since 1^st July 2008. Tin additions should now provide the required machinability. The present study exhibits the effects of alloying element variations of Cu, Mg and Mn on materials characteristics like microstructure or mechanical properties in the AlCuMgSn wrought alloy. Moreover, altered material behaviours at machining are determined. The focus of the investigation is a comprehensive alloy specification with the objective of finding an optimised alloy composition for good machinability or for balanced mechanical properties. It can be seen that medium Cu contents exhibit a good compromise between sufficiently high strength and simultaneous good machinability. A higher Mn content facilitates free cutting, whereas the Mg content has to be low to guarantee good machinability.     

混合熵对定向凝固锰铜基阻尼合金组织与性能的影响北大核心

使用动态热机械分析仪、光学显微镜(OM)、X射线衍射仪(XRD)和扫描电子显微镜(SEM)研究了不同成分梯度的定向凝固锰铜基合金的微观组织、阻尼行为以及力学性能特征。结果表明,在定向凝固过程中,随着合金元素的添加,枝晶间距逐渐减小,成分偏析程度增加,物相组成变为单一的母相,熵增引起的成分过冷使得枝晶易于断裂。添加镍与铁元素可以提高低温端孪晶的内耗值,而在加入锌元素后,MnCuNiFeZn合金在673 K下的内耗升高至0.023。随着混合熵的增加,三种不同成分梯度的定向凝固锰铜基合金的抗拉强度与伸长率均线性增加,合金应变硬化率的平稳保持段的斜率与混合熵呈正相关。     

添加CeO2对W-6Ni-4Co合金组织与性能的影响研究

采用冷压烧结法,以W、Ni、Co为原料,添加微量CeO2,制备W-6Ni-4Co合金。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、显微硬度仪等分析测试合金相组成、组织结构和力学性能,研究CeO2添加量对合金组织、性能的影响,并探讨CeO2对合金烧结致密化、相组成及分布、相长大和力学性能的作用机制。结果表明,W-6Ni-4Co合金主要由W、Co7W6、CeO2、Ni和Co相组成,增加CeO2添加量,抑制局部烧结合金化及W相长大,使Co7W6相减少、W相细化以及孔隙增加;添加0.1%CeO2合金组织细小、黏结相分布均匀,减弱了孔隙的性能弱化效应,使其力学性能最优。     

铜-二硫化钼复合材料的显微组织与性能研究

采用粉末冶金法在H2保护气氛下制备Cu-MoS2复合材料,对其进行物相分析和显微组织观察.通过测试密度、硬度、抗弯强度及电阻率,研究MoS2含量变化对复合材料组织与性能的影响.结果表明,MoS2含量不同,烧结产物发生变化,对复合材料的组织与性能影响较大.在烧结过程中,MoS2与基体发生反应,生成铜钼硫化合物、Cu的硫化物和金属Mo.复合材料中物相分散均匀,随MoS2含量增加,基体铜相不断减少,化合物增多,金属Mo弥散镶嵌其中;材料的密度不断减小;随MoS2含量增加,硬度先增后减,再回升;抗弯强度总体呈下降趋势;电阻率明显增大.     

La原料对LaMg17Ni储氢合金性能影响研究

为降低LaMg_(17)Ni储氢合金的成本并解决原材料La不稳定导致的安全问题,采用了La-H粉和La-Mg合金粉两种性能稳定且成本较低的原料替代La粉,利用机械合金化法制备了不同原料的LaMg_(17)Ni储氢合金,并对比两种不同原料制备合金的性能,探究性能差异的原因。采用比表面仪检测合金比表面积变化,用扫描电子显微镜(SEM)表征合金微观形貌,X射线衍射(XRD)表征合金制备前后和吸放氢前后相结构变化,利用高温高压气体吸附仪测试合金的吸放氢曲线、储氢量以及储氢速度。结果表明,以La-H粉为原料制备的合金储氢量达到4.58%,在3MPa氢气压力、温度573K以下,储氢速度为90s内达到饱和储氢量的90%以上,而以La-Mg合金粉原料制备的合金储氢量达到4.43%,在3MPa氢气压力、温度573K以下,储氢速度为120s内达到饱和储氢量的90%以上。由于La-H粉的高脆性使其在机械合金化过程中产生了更高的比表面活性以及内部原有LaH3相的直接催化作用,因此以La-H粉为原料制备的LaMg_(17)Ni合金储氢性能优于以La-Mg合金粉为原料制备的LaMg_(17)Ni合金。     

Coarsening Investigations of Precipitates in PM Tool Steel Grades: an Effect of Nitrogen

We present experimental and theoretical comparisons of the coarsening rate for the MX (X?=?C, N or C?+?N) precipitate in five different tool steel grades produced by Powder Metallurgy (PM). The alloys contain different amounts of nitrogen and carbon; ranging from high carbon/low nitrogen to high nitrogen/low carbon. Common for the grades is a high amount of precipitate forming alloying elements resulting in a high fraction of hard phase. Experimentally we have found out that the nitrogen rich precipitates coarsen slower, both for higher and lower carbon content, than the carbon rich precipitates. Coarsening simulations are performed utilizing the DICTRA software and an agreement between calculations and measurements can be concluded.     

粉末冶金Fe-2Cu-xC合金的性能研究

采用还原铁粉、雾化铁粉、电解铜粉和石墨作为原材料,用预混合法和直接机械混合法对粉末进行混合,得到Fe-2Cu-xC混合粉末后压制和烧结.同时探索了混合工艺对混合粉末性能的影响,并研究了碳含量对Fe-2Cu-xC合金材料的烧结性能和组织的影响.研究结果表明:预混合法比直接机械混合法的混合粉末压制性能更好,碳含量提高了铁铜碳合金材料的综合力学性能和烧结尺寸精度.     

挤压态Mg-9Li-xAl-0.6Y合金组织与力学性能研究

对Mg-9 Li-xAl-0.6 Y(x=0、3％、6％、9％)合金进行挤压实验.采用光学显微镜(OM)、拉伸实验机和扫描电子显微镜(SEM)表征分析Al元素含量的变化对合金的显微组织、力学性能和断口形貌的影响.结果表明:随着Al含量的增加,合金中的α-Mg相数量增多的趋势为先上升后下降,β-Li相数量的变化与之相反;...     

一种粉末冶金高氮不锈钢材料的研究

采用水雾化304不锈钢粉末与氮气雾化的高锰不锈钢粉末为原料,经混合、成形和高温真空烧结后,在不同温度下进行渗氮.结果表明:随着渗氮温度的升高,氮含量增加,抗弯强度增加.当w(N)＞0.6％时,抗弯强度略有降低.材料的盐雾腐蚀等级随氮含量的增加而降低,硬度随氮含量的增加而增加.     

矸石粉替代粉煤灰膏体充填材料性能研究

针对传统煤矿膏体充填材料对粉煤灰的需求量较大、成本较高的问题，研究矸石粉替代粉煤灰作为辅料时的膏体充填材料性能，采用正交试验方法以及MATLAB进行线性回归预测和3D可视化模型的建立，分析水掺量和水泥掺量对膏体充填材料流动性和力学性能的影响规律。试验结果表明：随着水泥掺量的增加，充填料浆流动性缓慢下降，同龄期抗压强度也持续缓慢增加，且1～3d变化较明显，3～28d变化较小|水掺量是影响流动性的主要因素，尤其是对充填料浆的扩展度的影响最为明显，随着水掺量的增加，同龄期抗压强度在显著减少，且龄期越长，结果越为明显。综合分析得出最优配比为15%水泥掺量，23%水掺量的充填材料，既满足充填强度要求也满足膏体的流动性要求。     

铝含量对Mg-6Zn系合金显微组织和力学性能的影响

研究了铝含量对Mg-6Zn系合金显微组织和力学性能的影响。结果表明:当铝含量为2%时, 合金晶粒细小, 并具有最佳的强度、硬度和塑性组合;随着铝含量增加, 合金中出现粗大的金属间化合物相, 特别是含6%Al 的合金中出现了粗大的、沿晶界连续分布的Mg₁₇Al₁₂相, 导致抗拉强度和延伸率下降。     

地质聚合物原位转化沸石及其氨氮吸附特性

以高铝粉煤灰、钢渣为前驱体,采用化学发泡原理制备类沸石相多孔粉煤灰-钢渣地质聚合物,通过水热反应原理将上述地质聚合物原位转化为沸石.采用X射线衍射(XRD)仪、扫描电镜(SEM)定性分析碱液浓度、温度及时间对原位转化沸石结构形态的影响规律.以多孔地质聚合物原位转化沸石为吸附剂,结合吸附容量分析初始氨氮质量浓度、pH值及...     

Si添加对快速凝固/粉末冶金镁合金组织及力学性能的影响

采用快速凝固/粉末冶金工艺分别制备Mg-8Al-0.5Zn-0.15Mn及Mg-8Al-0.5Zn-0.15Mn-2Si合金挤压棒材。利用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)及拉伸机,研究了Si添加对Mg-Al-Zn-Mn合金显微组织及室温力学性能的影响。结果表明,与热压Mg-Al-Zn-Mn合金相比,热压Mg-Al-Zn-Mn-Si合金内晶界上网状分布的Mg17Al12相减少,晶内出现多边形状Mg2Si相。热压后的反向挤压过程中Mg-Al-Zn-Mn合金与Mg-Al-Zn-Mn-Si合金组织均发生连续动态再结晶,其中Mg-Al-Zn-Mn-Si晶粒细化较好,伸长率较大,第二相Mg2Si与基体接合良好,但Mg2Si相周围出现的应力集中导致屈服强度和抗拉强度降低。随着反向挤压温度上升,反向挤压制备的两种合金屈服强度和抗拉强度均降低,而伸长率增大。     

机械合金化法制备Ti基储氢合金的进展

介绍机械合金化法Ti基储氢合金研究的进展，并展望其发展趋势。机械合金化工艺设备简单、成本低、污染小、安全性能好，完全符合高新技术研究和发展的思路。钛基储氢合金兼有吸放氢动力学和储氢量的优势，应用前景广阔。     

纳米晶块体Co-45Ni-10Cr合金在H2SO4溶液中腐蚀电化学行为研究

利用粉末冶金工艺制备常规尺寸（CS）Co-45Ni-10Cr合金粉末,再利用机械合金化法制备纳米尺寸（NS）Co-45Ni-10Cr合金粉末,采用真空热压技术得到相应的块体Co-45Ni-10Cr合金。腐蚀介质选择不同浓度的H2SO4溶液,利用电化学工作站分别测试两种Co-45Ni-10Cr（CS和NS）块体合金的自腐蚀电位、动电位极化曲线和交流阻抗谱,对比研究了它们的腐蚀行为以及晶粒细化对于它们腐蚀行为产生的影响。结果表明：两种Co-45Ni-10Cr（CS和NS）块体合金的自腐蚀电位均随腐蚀介质H2SO4溶液浓度增大而发生负移,腐蚀倾向逐渐加剧,同时腐蚀电流密度均增大,电荷传递电阻相应减小,因此腐蚀速度加快。此外,两种Co-45Ni-10Cr（CS和NS）块体合金的交流阻抗谱均为单一容抗弧,说明腐蚀速率均由电化学过程控制。与Co-45Ni-10Cr（CS）合金相比,Co-45Ni-10Cr（NS）合金的腐蚀速率减慢,这表明纳米化后Co-45Ni-10Cr块体合金的耐腐蚀性能有所提高。     

Einsatz von Bleilegierungsanoden in Metallgewinnungselektrolysen

In metal electrowinning processes different lead alloys are used as insoluble anodes. Demands on the anode material are low corrosion rates for a long life time, low oxygen overvoltage to minimize the specific energy consumption and good mechanical stability. In recent years, mainly the production processes and the concentration range of the alloying elements were optimized to improve the anode properties. Steps of this development were transferred from investigations to optimize the grid materials for lead SLI accumulators. In copper electrowinning the PbSb anodes used in the past have been replaced to a large extent by PbSnCa alloys. These anodes have relatively good mechanical properties and a sufficient corrosion rate, but a relatively high anode potential. Until now, in zinc electrowinning anodes made of PbAg alloys are used.     

球磨法制备Co-Zr非晶软磁合金粉末

在高纯氩气保护气氛下,采用FritshGmbh公司生产的Pulverisette5行星式球磨机,研究Co基非晶软磁合金粉末在Co Zr二元相图上5个稳定化合物成分配方Co1 1 Zr2 ,Co4 Zr ,Co2 Zr,CoZr和CoZr2 在球磨条件下的非晶态合金形成能力。用X 射线衍射进行结构分析。5种配方在一定的时间内都能形成非晶态合金,其中Co4 Zr的非晶形成能力最强,球磨过程中有CoZr2 相出现。球磨时间过长,使形成的非晶态合金粉体向晶体转化