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41.
42.
目前Ti6Al4V合金粉体的生产方法主要有雾化法、机械合金法和氢化脱氢法,它们都以Kroll法生产海绵钛为基础。使用钛的氧化物作为原料的熔盐电解法和金属热还原法仍处于研究阶段。本文依据变价金属Ti和V的氧化物在还原过程中逐级还原的特性,提出使用金属氧化物(TiO2, V2O5)作为原料的多级深度还原法制备Ti6Al4V合金粉体的新思路。首先计算了TiO2-V2O5-Mg-Ca体系的吉布斯自由能变,结果表明先进行镁热自蔓延反应,后进行钙热深度还原反应制备Ti6Al4V合金粉体在热力学上具备可行性。然后通过实验进行了的验证。镁热自蔓延反应产物酸浸后除去MgO可得到氧含量为15.84%的多孔Ti-Al-V-O前驱体。配入金属Ca后进行深度脱氧可得到低氧Ti6Al4V合金粉体(Al: 6.2wt.%, V: 3.64wt.%, O: 0.24wt.%, Mg: 0.01wt.%, Ca: < 0.01wt.%)。 相似文献
43.
本文使用Prophet人工智能算法研究与预测移动通信网络“潮汐效应”现象,探索网络“潮汐效应”在优化网络资源配置实现网络降本增效的作用。Prophet人工智能算法是一种简单、有效,且易于实现的人工智能算法。通过facebook的人工智能开源框架fbprophet,研究4G网络PRB利用率等网络资源指标的“潮汐效应”,并预测这些网络资源指标在未来的变化趋势,用来指导当前4G网络减容、扩容和4/5G节电节能等,实现优化网络资源配置达到降本增效的目的。 相似文献
44.
乡村产业中的化石能源设备逐渐被电能技术替代,引起了乡村负荷波动增大、部分时段产生集中高负荷的问题。为了解决以上问题,将低品位清洁能源应用至乡村的茶叶生产中,针对烘茶全过程的工艺要求提出了跨临界CO2热泵烘茶技术;并以某茶叶生产乡村为对象,对其代表台区的全年日用电量及产茶日负荷进行了分析,得出采用CO2热泵烘茶后其负荷得到大幅度削减,整体可降低至原负荷的39.6%~46.8%,峰值负荷与平时负荷的比值由原本的13.6降至5.4~6.2。跨临界CO2热泵应用至农产品生产中可有效缓解乡村供电压力。 相似文献
45.
《Ceramics International》2022,48(17):24471-24475
Al2O3–SiC composite powder (ASCP) was successfully synthesized using a novel molten-salt-assisted aluminum/carbothermal reduction (MS-ACTR) method with silica fume, aluminum powder, and carbon black as raw materials; NaCl–KCl was used as the molten salt medium. The effects of the synthesis temperature and salt-reactant ratio on the phase composition and microstructure were investigated. The results showed that the Al2O3–SiC content increased with an increase in molten salt temperature, and the salt–reactant ratio in the range of 1.5:1–2.5:1 had an impact on the fabrication of ASCP. The optimum condition for synthesizing ASCP from NaCl–KCl molten salt consisted of maintaining the temperature at 1573 K for 4 h. The chemical reaction thermodynamics and growth mechanism indicate that the molten salt plays an important role in the formation of SiC whiskers by following the vapor-solid growth mode in the MS-ACTR treatment. This study demonstrates that the addition of molten salt as a reaction medium is a promising approach for synthesizing high-melting-point composite powders at low temperatures. 相似文献
46.
《International Journal of Hydrogen Energy》2021,46(58):29812-29821
This study investigates the effect of two different iron compounds (zero-valent iron nanoparticle: nZVI and iron oxide nanoparticles: nIO) and pH on fermentative biohydrogen production from molasses-based distillery wastewater. The nZVI and nIO of optimum particle sizes of 50 nm and 55 nm respectively were synthesized and applied for fermentative hydrogen (H2) production. The addition of nIO & nZVI at (0.7 g/L, pH: 6) resulted in the highest H2 yield, H2 production rate, H2 content and COD reduction. Moreover, the kinetic parameters of H2 production potential (P) and H2 production rate (Rm) increased to 387 mL, and 22.2 mL/h, respectively for nZVI, these values were 363 mL and 21.8 mL/h for nIO. The results obtained indicated the positive effect of nZVI and nIO addition on enhanced fermentative H2 production. The addition of nZVI & nIO resulted in 71% and 69.4% enhancement in biohydrogen production respectively. 相似文献
47.
《International Journal of Hydrogen Energy》2021,46(55):28011-28020
Transition metal-based compounds, due to their excellent ORR catalytic performance under alkaline condition, have recently emerged as one of the most promising alternatives to noble metal-based ORR catalysts. It is worth noting that manganese oxide can take an unique advantage for decomposition of intermediate adsorption products H2O2 and can effectively reduce O2 to OH−. However, most research has focused on MnO2, while attention has rarely been paid to MnO catalysts. In addition, under high-temperature pyrolysis condition, MnO is the most stable manganese oxide but MnO nanoparticles easily agglomerate. Hence, it is very difficult to obtain well-dispersed and small-sized MnO nanoparticles. Herein, on the basis of pre-synthesizing uniformly distributed manganese complexes on the reduced graphene oxide (rGO), we innovatively prepare highly dispersed and small-sized MnO nanoparticles (~3.94 nm) via high-temperature pyrolysis, which are uniformly anchored on N-doped reduced graphene oxide (NrGO) as an efficient oxygen reduction electrocatalyst. The as-obtained MnO/NrGO (1050 °C) electrocatalyst achieves satisfactory onset potential (0.942 V) and half-wave potential (0.820 V) under alkaline condition. And the limiting current density is 4.17 mA cm−2, which is very close to that of Pt/C (20 wt%, JM). Meanwhile, MnO/NrGO (1050 °C) catalyst presents superior longstanding durability and methanol resistance than Pt/C (JM). This work indicates that high-temperature pyrolysis can improve the purity of manganese oxide, simultaneously the defects of NrGO can reduce particle size of MnO nanoparticles, which are greatly beneficial to improve ORR performance. This work provides a new idea for research of MnO catalysts for ORR in the future. 相似文献
48.
Yan Luo Zeming Tang Guiqiang Cao Da Bi David P. Trudgeon Adeline Loh Xiaohong Li Qingxue Lai Yanyu Liang 《International Journal of Hydrogen Energy》2021,46(2):1997-2006
Atomically dispersed transition metals anchored on N-doped carbon have been successfully developed as promising electrocatalysts for acidic oxygen reduction reaction (ORR). Nonetheless, how to introduce and construct single-atomic active sites is still a big challenge. Herein, a novel concave dodecahedron catalyst of N-doped carbon (FeCuNC) with well confined atomically dispersed bivalent Fe sites was facilely developed via a Cu-assisted induced strategy. The obtained catalyst delivered outstanding ORR performance in 0.5 M H2SO4 media with a half-wave potential (E1/2) of 0.82 V (vs reversible hydrogen electrode, RHE), stemming from the highly active bivalent Fe-Nx sites with sufficient exposure and accessibility guaranteed by the high specific surface area and curved surface. This work provides a simple but efficient metal-assisted induced strategy to tune the configurations of atomically dispersed active sites as well as microscopy structures of carbon matrix to develop promising PGM-free catalysts for proton exchange membrane fuel cell (PEMFC) applications. 相似文献
49.
Chunyu Zhang Guozhu Liu Bo Ning Shuairen Qian Danning Zheng Li Wang 《International Journal of Hydrogen Energy》2021,46(27):14277-14287
The electrochemical oxygen reduction reaction (ORR) via two-electron pathway is a sustainable way of producing hydrogen peroxide. Nanostructured carbon materials are proved to be effective catalysts for 2e? ORR. Herein, a series of mesoporous carbon with tunable nitrogen species and oxygen functional groups were synthesized by varying the added amount of dopamine hydrochloride as nitrogen and oxygen source. The modified catalysts exhibited higher content of pyrrolic-N and ether C–O groups which are confirmed by a series of characterization. Raman spectra and correlation analysis revealed that the increased proportion of defect sites in carbon materials are closely related to the introduced pyrrolic-N and ether C–O groups. And the rotating ring-disk electrode (RRDE) measurement carried out in 0.1 M KOH electrolyte showed the H2O2 selectivity increased with the content of defect sites. Among them, the optimized catalyst (NOC-6M) exhibited a selectivity of 95.2% and a potential of 0.71 V vs. RHE at ?1 mA cm?2. Moreover, NOC-6M possessed the high H2O2 production rate of 548.8 mmol gcat?1 h?1 with faradaic efficiency of 92.4% in a two-chamber H-cell. Further mechanistic analysis revealed that the introduction of pyrrolic-N and ether C–O are likely to improve the binding energy of the defect sites toward 1OOH intermediate, resulting in a more favorable 2e? ORR pathway for H2O2 production. 相似文献
50.
Deok-Hye Park Yo-Seob Kim Sang-Beom Han Woo-Jun Lee Hak-Joo Lee Yong-Soo Lee Sang-Hyun Moon Kyung-Won Park 《International Journal of Hydrogen Energy》2021,46(43):22499-22507
Electrochemical reactions such as the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and methanol oxidation reaction (MOR) are essential for energy conversion applications such as water electrolysis and fuel cells. Furthermore, Pt or Ir-related materials have been extensively utilized as electrocatalysts for the OER, ORR, and MOR. To reduce the utilization of precious metals, innovative catalyst structures should be proposed. Herein, we report a bi-metallic phosphide (Ni2P and PdP2) structure surrounded by graphitic carbon (Ni–Pd–P/C) with an enhanced electrochemical activity as compared to conventional electrocatalysts. Despite the low Pd content of 3 at%, Ni–Pd–P/C exhibits a low overpotential of 330 mV at 10 mA cm?2 in the OER, high specific activity (2.82 mA cm?2 at 0.8 V) for the ORR, and a high current density of 1.101 A mg?1 for the MOR. The superior electrochemical performance of Ni–Pd–P/C may be attributed to the synergistic effect of the bi-metallic phosphide structure and core-shell structure formed by graphitic carbon. 相似文献