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71.
《Ceramics International》2017,43(10):7674-7681
In the current study, the wettability between Fe-Al alloy and sintered MgO substrate was investigated. The stable contact angle between the sintered MgO substrate and the liquid iron was approximately 134° at 1550 °C, hardly influenced by Al concentrations of 18 ppm and 370 ppm in the liquid iron. By changing hydrogen partial pressure from 0 vol% to 1 vol%, the oxygen partial pressure decreased. Meanwhile, the contact angle between the MgO substrate and the liquid iron with 370 ppm Al increased with the decrease of oxygen partial pressure. The oxygen partial pressure and contact angle were scarcely affected by increasing hydrogen partial pressure from 1 vol% to 5 vol%. In all cases with 370 ppm Al in the liquid iron, oxide layers were detected on the surface of iron samples. The oxidation of iron could be effectively prevented by increasing the hydrogen partial pressure. The MgO substrate was reduced to Mg vapor in the reducing atmosphere at a high temperature. Then the Mg vapor was dissolved into the iron even before iron melting. Under thermodynamic equilibrium condition, an oxide layer containing two components, i.e. MgO·Al2O3 phase and CaO-SiO2-MgO-Al2O3 phase, was generated on the surface of the iron sample. Due to the different wettability between the iron and the two phases, MgO·Al2O3 phase was repelled, while the CaO-SiO2-MgO-Al2O3 phase adhered to the inside area. 相似文献
72.
Yong Wang Xiaochen Liu Tiliu Jiao Jinping Niu 《Journal of surfactants and detergents》2017,20(1):183-191
Comparison of surface and interfacial properties of internal olefin sulfonates (IOS) and alpha olefin sulfonates (AOS) shows that hydrocarbon chain branching has a significant influence on interfacial properties at the air–water, pentadecane–water and parafilm–water interfaces. The isomeric branched IOS shows a higher critical micelle concentration and are more effective in reducing the surface tension at the air–water interface by occupying a larger area per molecule. IOS exhibits better dynamic air–water interfacial properties due to a lower meso-equilibrium surface tension. The equilibrium interfacial tensions for AOS and IOS have no remarkable difference at the pentadecane–water interface. The water wettability and electrolyte tolerance are enhanced with branched hydrocarbon chain olefin sulfonates. 相似文献
73.
74.
The thermal stability of α-Fe203 and γ-Fe2O3 nanowires was studied by post annealing the samples at different temperatures. Before and after annealing, the samples were characterized by X-ray diffraction and scanning electron microscopy. The α-Fe2O3 nanowires are stable at the temperatures up to 600℃, and the crystalline structure becomes more perfect after annealing. This behavior supplies a way to improve the quality of the α-Fe2O3 nanowires. The γ-Fe2O3 nanowires become unstable when annealed at 350℃. Raman spectra of both nanowires have been measured, which also indicate that the γ-Fe203 nanowires are transformed into α-Fe2O3 under the strong laser beam. 相似文献
75.
主要研究内容包括如下几个方面: 粘结相 Ni- Co( Ni ∶ Co = 1 ∶1 , 质量比, 下同) 与不同 N/ C 比的硬质相 Ti( C, N)( Ti N/( Ti C+ Ti N) = 0 .1 ,0 .3 ,0 .5 ,0 .7 ,0 .9) 之间的润湿规律;粘结相 Ni- Co - Mo , Ni - Co - Ta , Ni- Co - Mo - C 与硬质相 Ti( C, N) 之间的润湿情况;以及在 Ti( C, N) 硬质相中添加 Ta C, Nb C 等对润湿性的影响。研究表明,当硬质相中 Ti N/ ( Ti C+ Ti N) < 0 .5 时宜采用 Ni - Co 作粘结相, 而当 Ti N/ ( Ti C+ Ti N) ≥0 .5时,则应选择 Ni- Co - Mo - C 作粘结相更适合。 相似文献
76.
《Contact lens & anterior eye》2020,43(3):285-297
Frequent replacement contact lenses made from the etafilcon A hydrogel lens material were introduced onto the market over 30 years ago, and etafilcon A remains the most widely used hydrogel lens material today. Although the prescribing of silicone hydrogel lenses is increasing, millions of lens wearers globally have been wearing hydrogel lenses for many years and exhibit a physiologically-stable ‘quiet eye’, with a low profile of adverse events. Hydrogel lenses are demonstrated to maintain a low inflammatory response and infection risk profile during daily wear, which in the case of etafilcon A, may be related to its low modulus, and the naturally-protective, anti-microbial, non-denatured lysozyme absorbed into the lens from the tear fluid. Although improved corneal physiology from decreased hypoxia with silicone hydrogel lenses is well accepted, equivalent levels of corneal oxygenation are maintained during daily wear of low to medium powered hydrogel lenses, which do not impede the daily corneal de-swelling process, and do not induce clinically significant changes in ocular health. Therefore, hydrogel lenses remain an important alternative for daily wear in modern contact lens practice. 相似文献
77.
《International Journal of Hydrogen Energy》2020,45(51):26595-26603
As the most important part of electrochemical reaction in proton exchange membrane electrolysis cells (PEMECs) for water splitting, oxygen evolution reaction (OER) occurs at the anode catalyst layer (CL). The distribution of the OER site is affected by many factors, such as properties of CL, operation parameters, procedures, etc. To study the effects of properties of CLs on the distribution of OER site on the CL, and consequently affect the performance of PEMECs, CLs with different sheet resistances are tested under different operation conditions. The phenomena of OER on CLs are captured by a high-speed and micro-scale visualization system in-situ and analysed coupled with electrochemical results. The results show that both sheet resistance and wettability of CLs have significant impact on the distribution of the OER site, which can help optimize the design of membrane electrode assembly and improve the operating parameters for electrochemical devices. 相似文献
78.
Chang-Whan Lee Byeong Wan Kwon Min-Goo Kang Hyung-Chul Ham Sung-Pil Yoon Jonghee Han Young Jin Kim Min Chul Lee 《International Journal of Hydrogen Energy》2017,42(29):18514-18523
In order to improve the stack life time of MCFCs, it is necessary to reduce the operating temperature of MCFCs below 600 °C, because reduced operating temperature minimizes electrolyte loss due to evaporation and corrosion. However, at the low operating temperature below 600 °C, the cell performance of MCFCs with (Li/Na)2CO3 electrolyte is too low to operate the fuel cell stack and system. In this study, we have performed wettability control of the liquid molten carbonate electrolyte by coating NiO cathodes with poor wetting property of the mixed ionic and electronic conductor (MIEC) such as BYS (Bi1.5Y0.3Sm0.3O3-δ). From experiments with symmetrical cells, each polarization component with various temperatures and gas conditions were studied. To investigate effects of the BYS coated cathode on the performance of MCFCs, a 100 cm2 single cell of MCFCs was employed. The performance of a 100 cm2 single cell with BYS coated cathode was better than that with conventional cathode by a factor of 1.84, because BYS coated cathode reduces activation polarization and mass transfer resistance greatly. 相似文献
79.
石墨烯由于其独特的二维结构和优异的物化性能,在改善复合材料的力学性能、电学性能和热学性能等方面具有很大的潜力,已成为金属基复合材料较理想的增强体。铜合金具有优异的导电导热性能和良好的延展性,但是其强度较低、不耐磨及高温下易变形的特点阻碍了其应用和发展。因此,结合石墨烯和铜的性能特点,将石墨烯作为增强体添加到铜中,制备性能优异的石墨烯增强铜基复合材料成为目前研究的热点之一。综述了目前石墨烯增强铜基复合材料的制备方法,并对各方法的特点进行了分析比较,提出未来可采用的制备工艺的方向以及在制备过程中面临的问题和挑战,并对其未来的研究方向进行了展望。 相似文献
80.
CuSn powders and TiH2 powders were milled using high energy mechanical milling to prepare Cu-based alloy powders for brazing diamond. And Ce was added to the milled Cu-based alloy powders to improve the wettability. It is found that the wetting angle reaches the minimum value 13.2° and the maximum spreading area 178 mm2 is achieved when the amount of Ce is 0.75 wt%. And Ce remarkably reduces the surface tension of liquid alloy, which improves the climbing height along the diamond and forms a massive support profile. And the results show that Ce can effectively improve the transverse rupture strength (TRS) due to high wettability. The wear characteristics of the diamonds brazed with Cu-based alloy containing 0.75 wt% Ce mainly consist of integrity, micro-fracture, fracture and rubdown, diamonds pull-out can not easily happen. 相似文献