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1.
对Inconel 690传热管材进行钨极气体保护焊(GTAW)对接焊,采用拉伸试验机、压扁试验机和光学显微镜测试和分析传热管焊接接头,同时利用ANSYS软件开展焊接接头在设计工况失压时的一次应力强度校核。研究结果表明:焊缝中心为树枝胞状晶,熔合线附近为粗大柱状晶。室温时接头的平均抗拉强度为619 MPa,平均屈服强度为292 MPa,350℃时接头平均抗拉强度为475 MPa,平均屈服强度为206 MPa,拉伸接头断裂从熔合区开始贯穿整个焊缝组织,呈塑性断裂。压扁试验和反向压扁试验结果表明管接头完好。通过ANSYS分析可知,设计工况下传热管接头350℃许用应力强度150 MPa限值可满足其一次应力强度要求,且裕量较大。 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(10):6700-6709
Water electrolysis is the most clean and high-efficiency technology for production of hydrogen, an ultimate clean energy in future. Highly efficient non-noble electrocatalysts for hydrogen evolution reaction (HER) are desirable for large scale production of hydrogen by water electrolysis. Especially, exposing as many active sites as possible is a vital way to improve activities of the catalysts. Herein, a series of new hydrangea like composite catalysts of ultrathin Mo2S3 nanosheets assembled uprightly and interlacedly on N, S-dual-doped graphitic biocarbon spheres were facilely prepared. The unique structure endowed the catalysts highly exposed edge active sites and prominently high activities for HER. Especially, the optimized catalyst Mo2S3/NSCS-50 exhibited as low as 106 mV of overpotential at 10 mA/cm2 (denoted as ?10). The catalyst also showed low Tafel slope of 53 mV/dec, low electron transfer resistance of 34 Ω and high stability evidenced by the result that the current density only attenuated 11.7% after 10 h i-t test. The catalyst has shown broad prospect for commercial application in water electrolysis. 相似文献
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《International Journal of Hydrogen Energy》2022,47(39):17241-17251
Zinc cadmium sulfide (ZnxCd1?xS) is a good photocatalyst for hydrogen evolution reaction (HER), but an optimum x (xm) at which a maximum HER rate is reached varies from one report to another. In this work, we examine the effect of light wavelength, not only for the HER to H2 in the presence of Na2S and Na2SO3, but also for oxygen reduction reaction (ORR) without addition of any sacrifices. For the HER under a 365 and 420 nm LED lamp, the xm were 0.9 and 0.7, respectively. For the HER under a 330 and 395–515 nm cut-off xenon lamp, the xm were 0.7 and 0.5, respectively. For the ORR under a 420 nm cut-off halogen lamp, a maximum production of H2O2 was observed at x = 0.3. Furthermore, after 4% ZnCo2O4 loading, ZnxCd1?xS had an increased activity and stability, either for the HER or for the ORR. Through a (photo)electrochemical measurement, it is proposed that the photocatalytic activity of ZnxCd1?xS is determined by its light absorptivity and electron reactivity. The improved performance of n-type ZnxCd1?xS by p-type ZnCo2O4 is due to formation of a p-n junction, promoting the HER (ORR) on ZnxCd1?xS, and the sulfide (water) oxidation on ZnCo2O4. This work highlights that ZnxCd1-xS is a promising photocatalyst for H2 and H2O2 production, respectively. 相似文献
6.
《International Journal of Hydrogen Energy》2022,47(28):13616-13628
Transition metals sulfide-based nanomaterials have recently received significant attention as a promising cathode electrode for the oxygen evolution reaction (OER) due to their easily tunable electronic, chemical, and physical properties. However, the poor electrical conductivity of metal-sulfide materials impedes their practical application in energy devices. Herein, firstly nano-sized crystals of cobalt-based zeolitic-imidazolate framework (Co-ZIF) arrays were fabricated on nickel-form (NF) as the sacrificial template by a facile solution method to enhance the electrical conductivity of the electrocatalyst. Then, the Co3S4/NiS@NF heterostructured arrays were synthesized by a simple hydrothermal route. The Co-ZIFs derived Co3S4 nanosheets are grown successfully on NiS nanorods during the hydrothermal sulfurization process. The bimetallic sulfide-based Co3S4/NiS@NF-12 electrocatalyst demonstrated a very low overpotential of 119 mV at 10 mA cm?2 for OER, which is much lower than that of mono-metal sulfide NiS@NF (201 mV) and ruthenium-oxide (RuO2) on NF (440 mV) electrocatalysts. Furthermore, the Co3S4/NiS@NF-12 electrocatalyst showed high stability during cyclic voltammetry and chronoamperometry measurements. This research work offers an effective strategy for fabricating high-performance non-precious OER electrocatalysts. 相似文献
7.
本文分析了乌兰矿投产前期采矿现状及存在的主要问题,针对该矿所处蒙古国经济落后、投资风险大的现实状况,为避免生产中断、规避投资风险,早日回收前期投资考虑,采取了双斜坡道开拓、全尾胶结充填、高端壁空场嗣后充填采矿、多中段组合式连续开采等系列技术应对方案。大大降低了一次性投资规模及投资风险,前期投资得以快速回笼的同时,矿山产能也充分释放,确保了矿山的持续稳定,取得了较好的经济和社会效益。为海外地下近地表矿体开采矿山规避投资风险提供了很好的技术方案借鉴。 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(51):21753-21759
Surface reconstruction produces metal oxyhydroxide (1OOH) active sites, and promoting surface reconstruction is essential for the design of OER electrocatalysts. In this paper, we reported that a large amount of active NiFeOOH was generated in-situ on the surface of nickel-iron sulfide selenide, thus exposing more active sites and efficiently catalyzing OER. In 1 M KOH solution, NiFeOOH(S,Se) achieves an ultra-low overpotential of 195 mV at the current density of 10 mA cm?2, and the Tafel slope is only 31.99 mV dec?1, showing excellent catalytic performance. When the current density is 100 mA cm?2, the over-potential of NiFeOOH(S,Se) in KOH + seawater solution is 239 mV, which is almost equivalent to 231 mV in KOH solution. The excellent OER stability of the NiFeOOH(S,Se) catalyst in alkaline electrolytes was confirmed, and the overpotential did not change significantly after 4 days of testing in KOH + seawater solution. 相似文献
9.
在新时期下,传统的英语教学方法已经不适合学生的学习和发展了,经过笔者的研究和分析发现,小学生对故事似乎是非常感兴趣,所以就针对多媒体技术在小学英语故事教学中的应用进行了几点尝试。 相似文献
10.
《Ceramics International》2019,45(13):15854-15859
Nowadays, transition metal sulfide (TMS), especially for spinel crystal structure (AxB3-xS4), have been proved to be a promising electromagnetic (EM) absorber if been used to deal with the severe electromagnetic pollution. However, EM performance degradation and absorption layer thickness-decreasing at present remains a big challenge, owning to the poor EM attenuation ability. To overcome this barrier, herein we reported a NixCo3-xS4 (x = 0, 0.3, 0.6, 1.0) absorber with hollow sphere structure to realize a good EM performance with a thinner matched thickness (<1.5 mm). The average sizes of these NixCo3-xS4 distributed in 450–550 nm. The dielectric loss ability (ε'') can be boosted by tuning the molar ratio of Ni/Co, which attributes to EM performance. Additionally, hollow structure would lead to the electromagnetic multi-reflection, also benefited to EM performance. The results demonstrated that the maximum qualified absorption bandwidth (fE) of 3.8 GHz can be achieved for the Ni0·3Co2·7S4 sample when specimen thickness only equals to 1.3 mm. 相似文献