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Effect of BaO and MgO on structure and properties of aluminate slag with various CaO/Al_(2)0_(3)ratios

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Journal of Iron and Steel Research(International) 2024年第1期31卷 204-214页

作者： Yu-qi Kong Ting Wu Wen-zhi Xia Wen Yang Hai-chuan Wang School of Metallurgical Engineering Anhui University of TechnologyMa’anshan243032AnhuiChina Key Laboratory of Metallurgical Emission Reduction and Resource Recycling(Ministry of Education) Anhui University of TechnologyMa’anshan243002AnhuiChina

To provide theoretical guidance for performance stability control of low-reactive mold fluxes,the effects of BaO and MgO on the structure and properties of aluminate slag with various CaO/Al_(2)0_(3)(C/A)ratios were investigated using the Fourier transform infrared spectrometer,Raman spectroscope,hemispherical melting point instrument,rotational viscometer and X-ray diffractometer.The results indicated that with BaO and MgO addition,the structure polymerization was first weakened and then enhanced at C/A of 1.1,and the transition contents corresponded to 8 wt.%BaO and 2 wt.%MgO,respectively,while the structure polymerization decreased continuously at C/A of 1.3.Since the viscosity change was well consistent with the structure evolution,the polymerization degree played a more prominent role in the slag viscosity than superheat degree when the melting temperature difference was within 40℃.The break temperature decreased initially and then increased with augment of BaO and MgO at C/A of 1.1,while it manifested a decrease trend with BaO addition,and it decreased obviously but then turned to increase with MgO increment at C/A of 1.3.The crystallization phase and crystallization ratio kept stable with BaO increment,while the crystallization ratio rose greatly with MgO promoting LiAlO_(2)precipitation at C/A of 1.1.The crystal types of all experimental slags were mainly Ca_(12)Al_(14)O_(33)and CaF_(2)at C/A of 1.3,and the precipitation of crystalline phase BaAl2O4 demonstrated a rising trend,while that of Ca_(12)Al_(14)O_(33)gradually declined with BaO augment.

关键词： Aluminate slag Structure MgO BaO Viscosity Property

1400℃放电等离子烧结制备MgO-B_(2)O_(3)增韧无金属黏结相WC硬质合金

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材料工程 2022年第11期50卷 73-80页

作者：赖佳明李京懋朱德智梁良屈盛官李小强华南理工大学国家金属材料近净成形工程技术研究中心广州510640

为了降低无金属黏结相碳化钨(WC)硬质合金的烧结温度并获得较高的断裂韧度,采用MgO和B_(2)O_(3)协同增韧WC硬质合金。通过放电等离子烧结技术(SPS)在1400℃的较低温度下制备出致密的WC-MgO-B_(2)O_(3)硬质合金块体材料,研究MgO-B_(2)O_... 详细信息

为了降低无金属黏结相碳化钨(WC)硬质合金的烧结温度并获得较高的断裂韧度,采用MgO和B_(2)O_(3)协同增韧WC硬质合金。通过放电等离子烧结技术(SPS)在1400℃的较低温度下制备出致密的WC-MgO-B_(2)O_(3)硬质合金块体材料,研究MgO-B_(2)O_(3)对无金属黏结相WC硬质合金的烧结机理、微观组织演变以及力学性能的影响规律。结果表明:MgO-B_(2)O_(3)的添加促进了WC的烧结致密化,显著降低了无金属黏结相WC硬质合金的烧结温度。随着MgO-B_(2)O_(3)添加量的提高,组织中的部分第二相形貌发生显著改变,逐渐由短杆状转变为长杆状,再转变为聚集时的块状。当MgO-B_(2)O_(3)添加量达到8%(质量分数)时,块体材料具有较好的断裂韧度,为(9.45±0.37)MPa·m^(1/2),同时其硬度为(18.16±0.17)GPa。

关键词： WC MgO B_(2)O_(3) 烧结机理组织演变力学性能烧结温度

腐蚀产物MgO对Fe基合金在固态和熔融NaCl-MgCl_(2)中高温耐蚀性能的影响

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稀有金属材料与工程 2022年第12期51卷 4452-4463页

作者：常丽梅张世洲文茜席吉辉吴波王军伟青海大学机械工程学院青海西宁810016 集美大学厦门市海洋腐蚀与智能防护材料重点实验室福建厦门361021 青海大学青海省高性能轻金属合金及深加工工程技术研究中心青海西宁810016

熔融氯化盐是下一代聚光式太阳能热发电站(第3代CSP)候选传热和储热介质,含MgCl_(2)的熔融氯化盐对金属传热管道和储热容器腐蚀后在其表面形成MgO,MgO对管道耐腐蚀性能影响尚不清楚。通过对比碳钢和3种Fe-Cr-Ni合金在固态(345℃)和熔融N... 详细信息

熔融氯化盐是下一代聚光式太阳能热发电站(第3代CSP)候选传热和储热介质,含MgCl_(2)的熔融氯化盐对金属传热管道和储热容器腐蚀后在其表面形成MgO,MgO对管道耐腐蚀性能影响尚不清楚。通过对比碳钢和3种Fe-Cr-Ni合金在固态(345℃)和熔融NaCl-MgCl_(2)(445和545℃)中的腐蚀行为,分析了MgO对4种试样在不同温度下的腐蚀行为机理。结果表明,在固态NaCl-MgCl_(2)中,碳钢表面MgO壳致密且连续,可以保护试样免受腐蚀。在熔融NaCl-MgCl_(2)中,4种试样表面也生成了致密的MgO壳,但它因热应力作用而开裂和剥落,熔融盐沿着氧化膜裂纹渗入MgO/基体界面,发生化学-电化学联合腐蚀反应,不能保护试样免受该熔盐腐蚀。

关键词： Fe-Cr-Ni合金碳钢熔融氯化盐腐蚀 MgO

Grain refinement of Mg-Ca alloys by native MgO particles

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Journal of Magnesium and Alloys 2024年第3期12卷 980-996页

作者： Shihao Wang Yun Wang Quentin M.Ramasse Zhongyun Fan Super STEM Laboratory SciTech Daresbury CampusDaresbury WA44ADUK School of Chemical and Process Engineering University of LeedsLeeds LS29JTUK BCAST Brunel University LondonUxbridgeMiddlesex UB83PHUK

In Mg-Ca alloys the grain refining mechanism,in particular regarding the role of nucleant substrates,remains the object of debates.Although native MgO is being recognised as a nucleating substrate accounting for grain refinement of Mg alloys,the possible interactions of MgO with alloying elements that may alter the nucleation potency have not been elucidated yet.Herein,we design casting experiments of Mg-xCa alloys varied qualitatively in number density of native MgO,which are then comprehensively studied by advanced electron microscopy.The results show that grain refinement is enhanced as the particle number density of MgO increases.The native MgO particles are modified by interfacial layers due to the co-segregation of Ca and N solute atoms at the MgO/Mg interface.Using aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy,we reveal the nature of these Ca/N interfacial layers at the atomic scale.Irrespective of the crystallographic termination of MgO,Ca and N co-segregate at the MgO/Mg interface and occupy Mg and O sites,respectively,forming an interfacial structure of a few atomic layers.The interfacial structure is slightly expanded,less ordered and defective compared to the MgO matrix due to compositional deviations,whereby the MgO substrate is altered as a poorer template to nucleate Mg solid.Upon solidification in a TP-1 mould,the impotent MgO particles account for the grain refining mechanism,where they are suggested to participate into nucleation and grain initiation processes in an explosive manner.This work not only reveals the atomic engineering of a substrate through interfacial segregation but also demonstrates the effectiveness of a strategy whereby native MgO particles can be harnessed for grain refinement in Mg-Ca alloys.

关键词： Mg-Ca alloy Grain refinement MgO Interfacial segregation STEM/EELS Solidification.

Expansion Performance and Microstructure of High-performance Concrete using Differently Scaled MgO Agents and Mineral Powder

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1335-1347页

作者： TIAN Changjin WANG Youzhi QIU Kai YANG Qilin School of Civil Engineering Shandong UniversityJinan 250002China China Construction Infrastructure Co. LtdBeijing 100089China School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin 150090China

To investigate the assumptions proposed in this paper,the evolution law governing the strength and expansion performance of MgO and nano-MgO micro-expansive concrete in the environment of mineral powder was firstly observed in this study.Secondly,SEM,XRD,and TG-DSC microscopic tests were conducted to reveal the effects of the active mineral-powder admixture on the hydration degree and expansion performance of MgO and nano-MgO in HPC.Our experimental results successfully verified our hypothesis,which indicated that the expansion performance of macro-MgO and nano-MgO was indeed depressed by the addition of active mineral power admixtures,even though the mechanical property of concrete composites was effectively improved.Furthermore,the hydration test also demonstrated the negative interference on the mineral powders,which was induced by the expansion agents.It is found the amounts of hydrates tend to decrease because the mineral powder ratio reaches and exceeds 40%.Moreover,it is also concluded the effect of expansion agents is governed by the alkalinity cement paste,especially for the nano-MgO.In other words,the expansion performance of nano-MgO will vary more obviously with the hydration process,than MgO.The results of this study provide that effective experimental and theoretical data support the hydration-inhibition mechanism of magnesium expansive agents.

关键词： MgO Nano-MgO mineral powders high-performance concrete expansive agents microstructures

Effect of Cu/Zn Substitution in MgO Nanostructures for Tuning the Optical Bandgap and Structural Properties

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Journal of Wuhan University of Technology(Materials Science) 2022年第6期37卷 1035-1040页

作者： ATIF Dawar S NASEEM Shah M ASIF Siddiqui YASMEEN Bibi Department of Physics Federal Urdu University of ArtsScience and TechnologyKarachiPakistan Department of Chemistry Federal Urdu University of ArtsScience and TechnologyKarachiPakistan

Low cost co-precipitation method was used to synthesize Cu(0-0.05)doped MgO samples with fixed concertation of Zn=0.01.X-ray diffraction(XRD)spectra confirmed the phase purity of the samples for 0≤Cu≤0.03 doping concentration.The secondary phase for 0.04≤Cu≤0.05 exhibited the formation of mixed metal oxides.The crystallite size was found to increase from 17.5 to 23.5 nm for 0≤Cu≤0.03 and then decreased from 22 to 18.5 nm for 0.04≤Cu≤0.05.The estimated bandgap first reduced from 5.48 to 4.88 eV and then increased from 5.21 to 5.36 eV.The morphology of the samples transformed from spheroidal shape to star-like shape.The obtained results reveal that the structural and optical property are in good agreement with the morphological transition.The peak shifting towards the lower values of vibrational frequency from 694 to 579 cm^(-1) confirms the incorporation of Cu/Zn in Mg-O lattice.The tuning of optical bandgap and structural properties with varying dopant concentration in MgO nanomaterials can be used for multifunctional modern energy storage and optoelectronic devices.

关键词： Cu/Zn doping MgO optical bandgap morphology vibrational modes

Highly dispersed Ni/MgO-mSiO_(2)catalysts with excellent activity and stability for dry reforming of methane

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Nano Research 2022年第6期15卷 5004-5013页

作者： Fang Zeng Juan Zhang Run Xu Rongjun Zhang Jianping Ge Shanghai Key Laboratory of Green Chemistry and Chemical Processes School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghai 200062China Department of Coal and Syngas Conversion Research Institute of Petroleum ProcessingSINOPECBeijing 100083China

Highly dispersed Ni catalyst and alkaline promoters supported by mesoporous SiO_(2)nanospheres were synthesized and applied as an active and stable catalyst for dry reforming of methane(DRM).The as-prepared Ni/MgO-mSiO_(2)catalyst showed stable conversions of CH4 and CO_(2)around 82%and 85%in 120 h of DRM reaction,which was superior in performance compared to similar catalysts in literatures.Based on the transmission electron microscope(TEM)images,energy-dispersive spectroscopy(EDS),CO-pulse adsorption,temperature programmed reduction of the oxidized catalysts by hydrogen(H_(2)-TPR),X-ray photoelectron spectroscopy(XPS),temperature-programmed desorption of CO_(2)(CO_(2)-TPD),and thermal gravitational analysis(TGA),the promotion effect of MgO on the Ni catalyst was systematically studied.The introduction of Mg^(2+)in synthesis enhanced the interaction between Ni^(2+)and mSiO_(2),which led to a high dispersion of active centers and a strong“metal–support”interactions to inhibit the sintering and deactivation of Ni at reaction temperatures.On the other hand,Ni and MgO nanoparticles formed adjacently on mSiO_(2),where the“Ni-MgO”interface not only improved the Ni0 distribution and promoted the cracking of CH_(4)but also promoted the activation of CO_(2)and the elimination of carbon deposits.A high and stable conversion of CH4 and CO_(2)were then achieved through the synergistic effect of Ni catalyst,MgO promoter,and mSiO_(2)support.

关键词： Ni-based catalyst dry reforming of methane mesoporous SiO_(2) MgO alkaline

Effects of water adsorption on active site-dependent H_(2)activation over MgO nanoflakes

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Nano Research 2023年第7期16卷 9059-9064页

作者： Aiyi Dong Kun Li Rentao Mu Conghui Liu Rongtan Li Haoran Jia Le Lin Qiang Fu School of Science Dalian Maritime UniversityDalian 116026China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Dalian National Laboratory for Clean Energy Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China

Understanding the effect of H_(2)O adsorption on reactant activation is of great importance in heterogeneous catalysis,which remains a grand challenge particularly in oxide catalyst systems with structural complexity.Herein,the effect of D_(2)O adsorption on D_(2)activation over MgO nanocatalysts at different temperatures has been investigated by transmission Fourier transform infrared(FT-IR)and temperature-programmed desorption(TPD).Two sets of hydride and hydroxyl species produced from D_(2)dissociation at more active and less active Mg-O pairs can be observed by FT-IR,which all desorb via the product of D_(2)as confirmed by TPD experiments.We find that the physically adsorbed D_(2)O overlayer does not affect the dissociation of D_(2)since D_(2)may pass through the molecular layer and access the surface-active sites.When D_(2)O is partially dissociated on the MgO surface,D_(2)can only dissociate at the remaining active sites until that dissociated-ODw groups from D_(2)O occupy all active sites.These findings provide a fundamental understanding of the effect of water adsorption on D_(2)activation on oxide catalysts.

关键词： H_(2)activation MgO hydride hydroxyl H_(2)O

时间切片离子速度成像技术关于MgO在193 nm的光解反应动力学研究

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Chinese Journal of Chemical Physics 2022年第2期35卷 257-262,I0001页

作者：李芳芳马玉杰刘嘉兴闫东徐昂王凤燕复旦大学化学系和上海市分子催化和功能材料重点实验室能源材料化学协同创新中心上海200438

本文利用时间切片离子速度成像技术对MgO分子在193 nm下的光解反应动力学进行了研究.实验通过产物M g的速度和角度分布分析,发现了三个光解反应路径.路径一为MgO(X^(1)∑^(+))态分子吸收一个光子到MgO(G^(1)Π)态,山于G^(1)Π,3^(3)Π和... 详细信息

本文利用时间切片离子速度成像技术对MgO分子在193 nm下的光解反应动力学进行了研究.实验通过产物M g的速度和角度分布分析,发现了三个光解反应路径.路径一为MgO(X^(1)∑^(+))态分子吸收一个光子到MgO(G^(1)Π)态,山于G^(1)Π,3^(3)Π和1^(5)Π态之间的自旋轨道耦合作用,反应沿着1^(5)Π的势能面解离生成产物Mg(^(3)P_(u))+O(^(3)P_(g)).路径二、三分别为MgO(A^(1)Π)态分子吸收一个光子到MgO(G^(1)Π)态和MgO(4^(1)Π)态,进而解离生成产物Mg(^(3)P_(u))+O(^(3)P_(g))和Mg(^(1)S_(g))+O(^(1)S_(g)).光解离路径的各向异性参数与振动能级的寿命以及转动和振动自旋轨道态的耦合有关.从总动能分析得到D_(0)(Mg-O)=21645±50 cm^(-1).

关键词：时间切片离子速度成像光解反应 MgO 振动态激发态 193 nm