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91.
研究了退火和固溶时效处理对热轧态TC4钛合金的力学性能和组织的影响,并考察了其冲击磨损性能。结果表明:退火处理后试样组织中转变β相增加,强度、塑性和韧性均较热轧态有所提升;而固溶时效处理后试样组织的晶粒细化且尺寸更为均匀,同时具有最高的强度,而塑性和韧性则较热轧态有所降低。经过10 h的冲击磨损试验后,退火态试样的磨损率最低,而固溶时效态试样的磨损率最高。通过磨损断口观察发现退火态试样表面冲刷犁沟较短,且终点处存在合金的塑性堆积,同时磨损面组织发生塑性变形,晶粒延展拉长。退火态试样较高的塑性和韧性有助于吸收冲击能量,因此表现出较好的耐冲击磨损性能。 相似文献
92.
木质素是自然界储量丰富的可再生天然酚类高分子,可替代传统化石资源应用于聚合物材料合成。木质素分子结构中的大分子刚性骨架可赋予材料独特的力学性能和热稳定性。但木质素化学组成和分子结构复杂、反应活性低,限制了在聚合物材料领域的应用。化学降解是一种高效、高选择性且应用广泛的降解方法,经化学降解处理得到的木质素低聚物具有活性官能团多、反应活性高、溶解性好等优点,有利于拓展木质素在聚合物材料领域的高附加值应用。重点综述了近年来国内外有关木质素化学降解及其降解产物应用于聚合物材料的研究进展。 相似文献
93.
94.
《Ceramics International》2021,47(20):28357-28366
Lithium titanium oxide (Li2TiO3) tritium breeder ceramic plates with nano- and coarse-grain size were fabricated. The preparation methods contained CTAB-modifying precursor, combining dry-pressing with isostatically cold-pressing, and calcinating at optimized sintering temperature in turn. Then their properties were characterized after radiation by 280 keV helium (He+) ion. Extensive characterization analyses were performed to reveal the changes in nano-grained and coarse-grained Li2TiO3 after radiation. They contained glancing angle X-ray diffraction (GIXRD), atomic force microscopy (AFM), electron spin resonance (ESR), and scanning electron microscopy (SEM). The results showed as follows, GIXRD peak position of the nano-grained Li2TiO3 was more stable than the coarse-grained Li2TiO3 after radiation. Nano-grained Li2TiO3 was less rough and swollen than the coarse-grained one after radiation. Nano-grained Li2TiO3 had more excellent structural stability and less defect concentration of Eʹ-center after radiation. As a result, nano-grained Li2TiO3 might have much better radiation tolerance than the coarse-grained one by comparing characterization results. 相似文献
95.
Jihong Li Yipu Liu Hui Chen Zhankai Zhang Xiaoxin Zou 《Advanced functional materials》2021,31(27):2101820
The realization of seawater electrolysis requires high-performing anode materials that should possess good catalytic activity, stability, and specificity for the oxygen evolution reaction (OER) as well as high resistance toward chloride corrosion. Herein, the design of a multilayered oxygen-evolution electrode is reported to meet the multiple needs of anode material for saline water splitting. The multilayered electrode is synthesized through direct thermal boronization of commercially available NiFe alloy plate with boron powder, followed by electrochemical oxidation. And this electrode is composed of the surface oxidized NiFeBx alloy layer, the NiFeBx alloy interlayer, and the NiFe alloy substrate. The boron species are present in the form of metaborate in the outermost oxidized NiFeBx layer, and their existence is conductive to the generation and stabilization of the catalytic active phase γ-(Ni,Fe)OOH. The introduction of NiFeBx interlayer effectively prevents the excessive oxidative corrosion of the anode material in the electrolyte containing chloride ions. 相似文献
96.
异己糖醇是一类碳水化合物衍生二元醇,具有高刚性、手性、亲水性和低毒等特性,在制备新型生物基、生物可降解高分子材料方面具有广阔的发展前景。围绕近年来研究较为充分的全脂肪型及半芳香型异己糖醇基均聚酯与共聚酯,综述了其合成、热学性能、力学性能、生物降解性能及潜在应用,探讨此类聚酯的高效聚合反应工艺及构效关系。异己糖醇结构单元的引入可有效提高聚合物的玻璃化转变温度,以及促进其水解和生物降解性能,在构建具有更高性能的环境友好型聚酯方面具有较高潜力,有望应用于工程塑料、纤维、生物医药等领域。此类生物基聚酯的大规模商业化需进一步开发更高效、温和的聚合反应工艺以攻克其热敏感和热降解问题。 相似文献
97.
E.A. Filonova E.Yu. Pikalova T.Yu. Maksimchuk A.I. Vylkov S.M. Pikalov A. Maignan 《International Journal of Hydrogen Energy》2021,46(32):17037-17050
Complex oxides Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0–0.4) have been prepared by a pyrolysis of glycerol-nitrate compositions. According to the X-ray diffraction analysis, the materials are single-phase up to y = 0.3 and crystallize in an orthorhombic structure (Bmab) at room temperature. High-temperature studies assert that they all undergo a phase transition from orthorhombic to tetragonal (I4/mmm) structure in a range of 300–400 °C. With Cu doping, the over-stoichiometric oxygen content δ decreases from 0.07 (y = 0.0) down to 0.00 (y = 0.3). The studies on the compact samples reveal the maximum value of total conductivity (165 S cm?1 at 420 °C) and the minimum value of the linear coefficient of thermal expansion (11.9·10?6 K?1 in a range of 400–1000 °C in air) at y = 0.2. Chemical compatibility of the Nd1.6Cа0.4Ni1-yCuyO4+δ (y = 0.0, 0.2) oxides with oxygen- and proton conducting electrolytes (Ce0.9Gd0.1O1.95, Ce0.8Sm0.2O1.9 and BaCe0.5Zr0.3Y0.1Yb0.1O3-δ) up to a temperature of 1100 °C is demonstrated. 相似文献
98.
S. Bharath Subramaniam Ramalingam Senthil 《International Journal of Hydrogen Energy》2021,46(43):22344-22355
A concentrated solar absorber with finned phase change materials was experimentally studied using a Scheffler type parabolic dish concentrator. The absorber's inner surface was fixed with hollow cylindrical containers filled with phase change material (PCM) for heat transfer augmentation. The absorber's selected PCM was acetanilide (Melting point of 116 °C)—the cylindrical capsules protruding into the fluid side to create turbulence and mixing and acting as fins. The absorber surface temperature was observed to be about 130–150 °C during the outdoor tests while passing fluid through the absorber. The fluid flow rate varied from 60 to 100 kg/h during the outdoor experiments. The peak energy and exergy efficiency of parabolic dish collector (PDC) at the fluid flow rate of 80 kg/h with PCM integrated solar absorber was found to be about 67.88% and 6.96%, respectively. The integration of cylindrical PCM containers resulted in more heat transfer augmentation in the solar absorbers. The optimized solar absorber could be suitable for various applications like steam generation, biomass gasification, space heating, and hydrogen generation. 相似文献
99.
Cafer Saka Mustafa Salih Eygi̇ Asım Balbay 《International Journal of Hydrogen Energy》2021,46(5):3876-3886
Inorganic acids such as hydrochloric acid (HCl), nitric acid (HNO3) and sulphuric acid (H2SO4) are generally used in the acid modification of clays. Here, CoB catalyst was synthesized on the acetic acid-activated kaolin support material (CH3COOH -kaolin- CoB) with an alternative approach. This prepared catalyst, firstly, was used to catalyze the hydrolysis of NaBH4 (NaBH4-HR). The structure of the raw kaolin, kaolin-CH3COOH, and CH3COOH-kaolin-CoB samples were characterized by X-ray diffraction spectroscopy (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscope (SEM), and nitrogen adsorption. At the same time, this catalyst performance was examined by Co loading, NaBH4 concentration, NaOH concentration, temperature and reusability parameters. The end times of this hydrolysis reaction using raw kaolin-CoB and CH3COOH-kaolin-CoB were found to be approximately 140 and 245 min, respectively. The maximum hydrogen generation rates (HGRs) obtained at temperatures 30 °C and 50 °C were 1533 and 3400 mL/min/gcatalyst, respectively. At the same time, the activation energy was found to be 49.41 kJ/mol. 相似文献
100.
Hydrodistillation condition adjustment for different material particle sizes: a method to increase batch‐to‐batch quality consistency 下载免费PDF全文
Danni Wei Guilin Cheng Kaiyi Huang Jinyang Fang Binjun Yan 《International Journal of Food Science & Technology》2018,53(5):1140-1148
Varying material particle sizes represent a common contributing factor to the batch‐to‐batch variation of extraction yields. To increase the batch‐to‐batch quality consistency of extracts, a method was proposed to adjust the extraction conditions for different material particle sizes, taking the hydrodistillation extraction process of Radix Curcumae and Fructus Gardeniae as a case study. Statistical models were built for five sesquiterpenes including curcumenone, curcumenol, curdione, curzerenone and furanodienone, to quantitatively describe the effects of particle size and process parameters on their extraction yields. An increase in sodium chloride concentration remarkably increased the yields of curcumenone and curcumenol, and a larger solvent‐to‐solid ratio increased the yields of five sesquiterpenes. Under the adjusted process parameters for two different particle sizes, the yield for each compound was controlled to fall in the 90–110% target range. The proposed method can be applied to various extraction processes of foods and herbal medicines. 相似文献