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借助于XRD、TG-DSC和SEM等技术研究了掺钛对氢化燃烧合成镁镍储氢合金的合成条件及合金性能的影响.结果表明:掺钛使Mg2NiH4的合成温度有一定的提高,600℃时才能大量生成Mg2NiH4;氢压的提高有利于Mg2NiH4的形成,而过高的合成温度和过长的保温时间将不利于Mg2NiH4的形成;钛的掺入使Mg2NiH4的晶胞有一定的增大;掺钛的Mg2NiH4放氢分解温度为259.8℃,比未掺钛的降低了120℃左右;掺钛试样的总放氢量为2.43%;掺钛试样在300℃、0.1MPa下的吸放氢时间为6min,活化可适当提高吸放氢量. 相似文献
95.
《Materials Science & Technology》2013,29(1):416-420
AbstractUltrafine grained nickel (UFG Ni) and microcrystalline nickel (MC Ni) were fabricated on two types of substrates, i.e. the amorphous (Ni–P) and polycrystalline (stainless steel) substrates by pulse electrodeposition without additives. This study demonstrates that when inhibiting the epitaxial growth by first depositing a thin amorphous layer on the polycrystalline substrates, the grain size of the subsequent Ni deposit decreases dramatically from microscale to the UFG regime, which depends on the deposition conditions. Compared with MC Ni, which has an ultimate tensile strength σUTS of 397 MPa and an elongation to failure εTEF of 11·98%, UFG Ni with an average grain size of 120·72 nm exhibits an enhanced σUTS of 807 MPa and a comparable εTEF of 10·44%. The electrodeposited method used in this study provides an effective and low cost way to produce UFG materials with both high strength and ductility, which can meet the demands for practical application as structural materials. 相似文献
96.
《Materials Science & Technology》2013,29(12):1793-1797
AbstractThe microstructures and tensile properties of electrodeposited nanocrystalline Ni (nc-Ni) with a broad grain size distribution after annealing at 150, 200 and 300°C for 500 s were investigated. The as deposited broad grain size distribution nc-Ni sample exhibited a moderate strength σUTS of ~1107 MPa but a markedly enhanced ductility ?TEF of ~10%, compared with electrodeposited nc-Ni with a narrow grain size distribution. Annealing below 200°C increased the strength but caused a considerably reduction in tensile elongation. This behaviour is attributed to the grain boundary relaxation and the increased order of grain boundaries after annealing, which can make the grain boundary activities, such as the grain boundary sliding and grain rotations, more difficult. Further annealing at 300°C decreased both the yield strength and tensile elongation significantly due to significant grain growth. 相似文献
97.
Preparations of PbS-coated titanium dioxide (TiO2) and lead sulfide (PbS) nanoparticles under ultrasonic field at the multibubble sonoluminescence (MBSL) conditions were tested in water solutions. Under the optimal MBSL conditions (20 kHz and 220 W power input), PbS nanoparticles (diameter = 40-50 nm) were prepared by treating lead nitrate and thioacetamide for 20 min in water solutions. The size of PbS nanoparticles was found to be easily increased to about 90 nm in diameter by increasing the reactant concentration twice. A similar sonochemical reaction with TiO2 nanoparticles (about 20-30 nm in diameter) gave rise to PbS-coated TiO2 nanoparticles with a core/shell structure. The PbS thin film coating was quite uniform and the average coating depth of PbS on the TiO2 nanoparticles was about 2-3 nm under the described conditions. It is interesting to note that the coating depth was found to be controlled to 2-10 nm range by increasing the amounts of reactants for Pb and S twice with a sonication time of 30 min. 相似文献
98.
AbstractSUS316L stainless steel and cobalt–chromium and platinum–chromium alloys are widely used platforms for coronary stents. These alloys also contain nickel (Ni), which reportedly induces allergic reactions in some subjects and is known to have various cellular effects. The effects of Ni on neointima formation after stent implantation remain unknown, however. We developed coronary stents made of Ni-free high-nitrogen austenitic stainless steel prepared using a N2-gas pressurized electroslag remelting (P-ESR) process. Neointima formation and inflammatory responses following stent implantation in porcine coronary arteries were then compared between the Ni-free and SUS316L stainless steel stents. We found significantly less neointima formation and inflammation in arteries implanted with Ni-free stents, as compared to SUS316L stents. Notably, Ni2+ was eluted into the medium from SUS316L but not from Ni-free stainless steel. Mechanistically, Ni2+ increased levels of hypoxia inducible factor protein-1α (HIF-1α) and its target genes in cultured smooth muscle cells. HIF-1α and their target gene levels were also increased in the vascular wall at SUS316L stent sites but not at Ni-free stent sites. The Ni-free stainless steel coronary stent reduces neointima formation, in part by avoiding activation of inflammatory processes via the Ni-HIF pathway. The Ni-free-stainless steel stent is a promising new coronary stent platform. 相似文献
99.
本研究采用简单的一步化学沉积法制备非晶纳米Nd-Ni-B/NF稀土复合电极并研究其析氢(Hydrogen evolution reaction, HER)性能。通过各种测试方法对纳米电极材料进行物相分析和形貌表征,并探索其电催化析氢性能和稳定性。结果表明, 稀土Nd可提高电极的电催化析氢性能, 当硝酸钕浓度为3 g?L-1时, 恒温35 ℃下施镀1 h, 制备的Nd-Ni-B/NF电极析氢性能最佳。Nd-Ni-B/NF(Nickel foam)电极在1.0 mol?L-1KOH 溶液中, 20 mA?cm-2电流密度下的析氢过电位仅为180 mV, Tafel斜率为117 mV?dec-1, 析氢反应由Volmer-Heyrovsky步骤控制。此外, Nd-Ni-B/NF电极具有优越的电化学稳定性, 在持续电解12 h或2000次循环伏安测试后, 催化剂的活性没有明显衰减。 相似文献
100.
Ahmed R. Weshahy Ahmed K. Sakr Ayman A. Gouda Bahig M. Atia H. H. Somaily Mohamed Y. Hanfi M. I. Sayyed Ragaa El Sheikh Enass M. El-Sheikh Hend A. Radwan Mohamed F. Cheira Mohamed A. Gado 《International journal of molecular sciences》2022,23(15)
Spent Ni–Cd batteries are now considered an important source for many valuable metals. The recovery of cadmium, cobalt, and nickel from spent Ni–Cd Batteries has been performed in this study. The optimum leaching process was achieved using 20% H2SO4, solid/liquid (S/L) 1/5 at 80 °C for 6 h. The leaching efficiency of Fe, Cd, and Co was nearly 100%, whereas the leaching efficiency of Ni was 95%. The recovery of the concerned elements was attained using successive different separation techniques. Cd(II) ions were extracted by a solvent, namely, Adogen® 464, and precipitated as CdS with 0.5% Na2S solution at pH of 1.25 and room temperature. The extraction process corresponded to pseudo-2nd-order. The prepared PTU-MS silica was applied for adsorption of Co(II) ions from aqueous solution, while the desorption process was performed using 0.3 M H2SO4. Cobalt was precipitated at pH 9.0 as Co(OH)2 using NH4OH. The kinetic and thermodynamic parameters were also investigated. Nickel was directly precipitated at pH 8.25 using a 10% NaOH solution at ambient temperature. FTIR, SEM, and EDX confirm the structure of the products. 相似文献