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1.
Laser aided additive manufacturing(LAAM)was used to fabricate bulk Fe49.5Mn30Co10Cr10C0.5 interstitial multicomponent alloy using pre-alloyed powder.The room temperature yield strength(σy),ultimate tensile strength(σUTS)and elongation(εUST)were 645 MPa,917 MPa and 27.0%respectively.The as-built sample consisted of equiaxed and dendritic cellular structures formed by elemental segregation.These cellular structures together with oxide particle inclusions were deemed to strengthen the material.The other contributing components include dislocation strengthening,friction stress and grain bound-ary strengthening.The high εUTS was attributed to dislocation motion and activation of both twinning and transformation-induced plasticity(TWIP and TRIP).Tensile tests performed at-40℃and-130℃demonstrated superior tensile strength of 1041 MPa and 1267 MPa respectively.However,almost no twinning was observed in the fractured sample tested at-40℃and-130℃.Instead,higher fraction of strain-induced hexagonal close-packed(HCP)ε phase transformation of 21.2%were observed for fractured sample tested at-40℃,compared with 6.3%in fractured room temperature sample. 相似文献
2.
Daniel CRUZ H.B.ORTIZ-OLIVEROS L.M.PéREZ-DíAZ R.M.FLORES-ESPINOSA G.ROSANO-ORTEGA 《中国有色金属学会会刊》2018,(9)
提出一种合成γ-LiAlO_2的替代解决方案—改进燃烧法直接合成γ-LiAlO_2,并将其用于相对简单的反应体系中,原料为非氧化性化合物如Al_2O_3和LiOH,燃料为尿素。采用1:1、1.5:1和2:1的非化学计量Li/Al摩尔比,在900和1000°C下反应5 min,制备LiAlO_2,并对其组织和结构进行表征。考察Li/Al摩尔比对材料形貌和高γ射线辐照下材料稳定性的影响。结果表明,所得粉体的晶体结构为?-LiAlO_2和?-LiAlO_2,其取决于Li/Al摩尔比。因此,用该方法可以成功合成微砖状、多面体状和层状?-LiAlO_2,而无需任何后续处理。γ辐照结果表明,所得到的?-LiAlO_2不分解,只形成少量的Li_2CO_3;由此可以确定,辐照会导致固结,不利于氚的有效提取;结果证明,用燃烧法生产高纯度?-LiAlO_2不需要硝酸盐前驱体。 相似文献
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The effect of the addition of small amounts of rare earths(Ln=La, Ce, Nd and Gd) to alumina supported copper-cobalt spinel oxide on the catalysts efficiency in CO and CH4 oxidation and in NO decomposition was investigated. Samples of Ln/Cu Co/Al catalyst were prepared and characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), atomic absorption spectroscopy(AAS), scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS), H2-temperature-programmed reduction(H2-TPR), electron paramagnetic resonance(EPR) spectroscopy and low temperature nitrogen adsorption. The results showed that the addition of rare earths changed the surface state of the alumina supported copper-cobalt spinel catalyst. As a result, partial reduction of copper species was observed as well as migration of these species between the surface and the bulk. The Ln/Cu Co/Al catalysts behaved differently in oxidation and reduction processes. In oxidation processes where oxide structure was important, Ce/Cu Co/Al and Nd/Cu Co/Al were the most active catalysts. The catalyst Ce/Cu Co/Al was the most active in the oxidation reactions because of the availability and favorable surface distribution of the redox couples Cu+/Cu2+ and Ce3+/Ce4+. In NO decompostion, Ln-modified catalysts significantly improved the selectivity of the process to N2. 相似文献
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Douglas G. Hayes 《粮油食品科技》2020,28(5):41-48
Surfactants are important chemical products, serving as emulsifiers and interfacial modifiers in the household detergents, personal care products, paints and coatings, foods, cosmetics, and pharmaceuticals industries. This review focuses upon recent advances in research and development to improve the ecological sustainability of surfactants throughout their life cycle, including derivation from renewable resources, production using green manufacturing principles, and improved biocompatibility and biodegradability during their consumer use and disposal stages. Biobased surfactants, derived from vegetable oils, polysaccharides, proteins, phospholipids, and other renewable resources, currently comprise approximately 24% of the surfactant market, and this percentage is expected to increase, especially in Asia. The use of renewables is attractive to consumers because of reduced production of CO2, a greenhouse gas associated with climate change. Enzymes can greatly increase process sustainability, through reduced use of organic solvent, water, and energy, and reduced formation of by-products and waste products. Among the enzymes being investigated for surfactant synthesis, lipases are the most robust, due to their relatively high biocatalytic activity, operational stability and their ability to form or cleave ester, amide, and thioester bonds. For enzymes to be robust catalysts of surfactants, further research and development is needed to improve catalytic productivity, stability and reduce their purchase cost. 相似文献
8.
In this study, the effects of changing first wall materials and their thicknesses on a reactor were investigated to determine the displacement per atom(DPA) and gas production(helium and hydrogen) in the first wall, as well as the tritium breeding ratio(TBR) in the coolant and tritium breeding zones. Therefore, the modeling of the magnetic fusion reactor was determined based on the blanket parameters of the International Thermonuclear Experimental Reactor(ITER). Stainless steel(SS 316 LNIG), Oxi... 相似文献
9.
C.E.BORJA I.A.FIGUEROA O.LOZADA-FLORES M.ESTRADA G.A.LARA-RODRíGUEZ J.A.VERDUZCO 《中国有色金属学会会刊》2018,(6)
分析ZrCuAlNi系大块金属玻璃的非晶形成能力、热学和力学性能。运用密实堆积和动态脆性指数模型从理论上确定合金的成分。采用铜模吸铸法在氩气保护下制备圆柱形和圆锥形铸锭。用X射线衍射表征圆锥形铸锭以便确定非晶结构。结果表明:两种合金的临界非晶直径为3 mm。用差示扫描量热法(DSC)分析其热行为,加热速率分别为0.5、0.67和0.83 K/s。γ参数、过冷液相区ΔT_x和约化玻璃转变温度T_(rg)等这些实验所得的参数均表明其具有高的非晶形成能力。非晶成分显示其脆性指数为40。合金的压缩试验采用的应变速率为0.016 s~(-1),得到弹性模量约为83 GPa,总应变约为5%,屈服强度为1.6 GPa,硬度为4 GPa。运用密实堆积和动态脆性指数模拟可以预测ZrCuAlNi系合金的非晶形成成分。 相似文献
10.
Zachary Freudenburg Khaterah Kohneshin Erik Aarnoutse Mariska Vansteensel Mariana Branco Sacha Leinders Max van den Boom Elmar G. M. Pels Nick Ramsey 《控制理论与应用(英文版)》2021,19(4):444-454
While brain computer interfaces (BCIs) offer the potential of allowing those suffering from loss of muscle control to once
again fully engage with their environment by bypassing the affected motor system and decoding user intentions directly from
brain activity, they are prone to errors. One possible avenue for BCI performance improvement is to detect when the BCI user
perceives the BCI to have made an unintended action and thus take corrective actions. Error-related potentials (ErrPs) are
neural correlates of error awareness and as such can provide an indication of when a BCI system is not performing according
to the user’s intentions. Here, we investigate the brain signals of an implanted BCI user suffering from locked-in syndrome
(LIS) due to late-stage ALS that prevents her from being able to speak or move but not from using her BCI at home on a
daily basis to communicate, for the presence of error-related signals. We first establish the presence of an ErrP originating
from the dorsolateral pre-frontal cortex (dLPFC) in response to errors made during a discrete feedback task that mimics the
click-based spelling software she uses to communicate. Then, we show that this ErrP can also be elicited by cursor movement
errors in a continuous BCI cursor control task. This work represents a first step toward detecting ErrPs during the daily
home use of a communications BCI. 相似文献