Achieving superior hydrogen storage properties via in-situ formed nanostructures: A high-capacity Mg–Ni alloy with La microalloying

Mg-based hydride is a promising hydrogen storage material, but its capacity is hindered by the kinetic properties. In this study, Mg–Mg₂Ni–LaH_x nanocomposite is formed from the H-induced decomposition of Mg₉₈Ni_1·67La_0.33 alloy. The hydrogen capacity of 7.19 wt % is reached at 325 °C under 3 MPa H₂, attributed to the ultrahigh hydrogenation capacity in Stage I. The hydrogen capacity of 5.59 wt % is achieved at 175 °C under 1 MPa H₂. The apparent activation energies for hydrogen absorption and desorption are calculated as 57.99 and 107.26 kJ/mol, which are owing to the modified microstructure with LaH_x and Mg₂Ni nanophases embedding in eutectic, and tubular nanostructure adjacent to eutectic. The LaH_2.49 nanophase can catalyze H₂ molecules to dissociate and H atoms to permeate due to its stronger affinity with H atoms. The interfaces of these nanophases provide preferential nucleation sites and alleviate the “blocking effect” together with tubular nanostructure by providing H atoms diffusion paths after the impingement of MgH₂ colonies. Therefore, the superior hydrogenation properties are achieved because of the rapid absorption process of Stage I. The efficient synthesis of nano-catalysts and corresponding mechanisms for improving hydrogen storage properties have important reference to related researches.     

微波合成无机纳米材料的研究进展

微波加热作为一种合成纳米材料的新方法，近年来得到飞速发展。介绍了微波加热原理，阐述了微波合成无机纳米材料的一些研究进展，主要是液相微波加热在制备金属氧化物和金属硫化物纳米材料以及微波烧结在合成陶瓷材料的应用，并对该领域未来作了一些展望。     

纳米堵剂在油田超深疑难井封堵上的应用研究

封堵技术是油田“控水稳油”的主导技术之一,在油田开发中应用普遍。然而,近年国内新投入开发的油田中有相当数量的埋藏深、高温、高压、高矿化度、低渗透难开发的油藏,常规封堵剂适应性和安全性差,无法满足现场需求。因此研究开发了一种新型纳米堵剂,并对其性能进行了室内评价。室内评价结果表明,纳米堵剂浆体流变性和注入性能好,初凝时间可调,具有强度高、封堵率高、溶解率高、析水量少且体积不收缩、耐地下高温等特性。现场应用也表明,与油田常用高强度堵剂相比,具有耐高温、高压、高矿化度,强度高和易溶解的优势,且施工安全简便,措施成功率高,是解决超深疑难井堵水的一种新型封堵剂。     

铝基纳米复合材料的电子显微镜研究

一种由部分非晶和部分晶体组成的新型铝合金可以用液态旋淬法直接制备，其力学性能非常优异。电镜观察表明这种纳米复合材料具有新颖的结构：纳米级Ａｌ晶体均匀弥散分布在非晶体上且无择优取向，Ａｌ晶体具有面心立方结构。高分辨电镜初步结果显示这种Ａｌ了无内部缺陷，但存在某种程度的畸变，且界面结构非常复杂。     

纳米层状双金属氢氧化物的制备及结构表征

采用恒定pH 12±0.2,按n(Mg2+)∶n(Al3+)∶n(OH-)∶n(CO2-3)=6∶2∶16∶1配制溶液,采用一步反应液相法,制备纳米层状双金属氢氧化物(LDH)粉体.为了获得无团聚、分散均匀的纳米粉体,探讨了溶剂置换干燥、真空干燥、常压干燥对纳米LDH粉体形成团聚的影响;用X射线衍射仪、透射电镜、红外光谱仪和元素分析仪对样品的物相、形貌、粒径和组成进行了表征.结果表明,溶剂置换干燥能够有效防止纳米粉体形成硬团聚,样品分散性好,呈针状形态,长50 nm,宽5 nm.     

Effect of Nanophase on the Nucleation of Intragranular Ferrite in Microalloyed Steel

MnS, MnS+V(C, N) complex precipitates in micro-alloyed ultra-fine grained steels were precisely analyzed to investigate the grain refining mechanism. The experimental results shows that MnS, MnS+V(C, N) precipitates provide nucleation center for Intra-granular ferrite (IGF), so that refined grain remarkably. Moreover, substructures such as grain boundary, sub-boundary, distortion band, dislocation and dislocation cell in austenite increased as the deformation energy led by heavy deformation at low temperatu...     

改性纳米SiO2对再生沥青胶结料性能的影响

为提高再生沥青的再生效果,文中采用RA-F0110型再生剂作为A型再生剂和OP-900型再生剂作为B型再生剂对旧沥青进行再生;采用硅烷偶联剂KH-550和KH-570对纳米SiO2进行有机化表面改性;对比不同速率、不同搅拌时间、不同静置时间下纳米再生沥青的PG高温分级温度,确定纳米再生沥青的制备方法;对比添加不同种类不同掺量再生剂后再生沥青的PG连续分级确定再生剂的种类和掺量;对比不同纳米SiO2掺量下纳米再生沥青的PG连续分级确定纳米材料的掺量。试验表明：纳米SiO2在表面改性后团聚现象减少。纳米粒子被包覆,所以纳米粒子尺寸增大导致单个粒子的比表面积明显减小,纳米SiO2在沥青中更加稳定,采用KH-550表面改性剂的效果优于KH-570。选用A型再生剂的再生沥青的再生效果优于选用B型再生剂的再生沥青。在相同再生剂掺量下,添加一定比例的纳米SiO2,纳米再生沥青PG连续分级的高低温服务范围更宽广。当纳米材料的掺量为5%,A型再生剂掺量为15%时,纳米再生沥青胶结料的性能指标达到最佳。     

纳米陶瓷超塑加工成形的研究进展

在对纳米陶瓷超塑性拉伸研究进行总结的基础上 ,综述了陶瓷超塑成形的研究进展情况。指出 :陶瓷材料由于其超塑特性 ,所以能够用各种现有的金属塑性成形方法来成形。最佳成形温度范围大约在 12 0 0℃～ 15 0 0℃之间 ,最佳晶粒平均直径为 10 0nm～ 2 0 0nm。