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Biochar 2023年第1期5卷 621-640页

作者： h.W.Kua s.m.h.Tan Department of the Built Environment College of Design and EngineeringNational University of SingaporeSingaporeSingapore

One of the challenges of promoting accelerated carbonation curing(ACC)of concrete as a carbon sequestration strategy is ensuring that carbonation will not deteriorate mechanical *** study examined the mechanical strength,water sorptivity and carbonation efficiency of ten types of mortar containing dry or pre-soaked biochar subjected to internal and/or external *** results obtained enabled a typology of ACC to be proposed,in which the carbon dioxide absorption of mortar containing various types of CO_(2)-dosed biochar ranged between 0.022%and 0.068%per unit dosage *** particular,the mortar containing dry biochar dosed with carbon dioxide was the top candidate for concurrently increasing both compressive strength(54.9 mPa)and carbon dioxide absorption(0.055%per unit dosage hour).mortar containing pre-soaked biochar dosed with carbon dioxide was identified as a strategy that achieved the highest carbonation efficiency(0.068%per unit dosage hour),but it also reduced compressive strength(45.1 mPa).Collectively,the proposed typology offers a useful overview of the different ways by which biochar can be used to tune ACC in mortar,according to any technical constraints and/or intended functions of the carbonated concrete components.

关键词： Biochar Pre-soaked Carbonation effectiveness Carbonation efficiency Accelerated carbonation curing

Phase Formation and magnetic Properties of Nanocomposite Nd-Fe-B Adjusted by small Amount of Dy and Co

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Journal of Rare Earths 2004年第z2期22卷 89-94页

作者： T s Jang T W Lim h s Aum D h Lee m B Kim Division of materials and Chemical Engineering Sun Moon UniversityKorea Division of Materials and Chemical EngineeringSun Moon UniversityKorea Division of Mechanical EngineeringSun Moon University 100 Kalsan LiTangjung MyonAsan CityChoongnam 336-708Korea Division of Materials and Chemical EngineeringSun Moon UniversityKorea Division of Materials and Chemical EngineeringSun Moon UniversityKorea

In order to improve and stabilize the magnetic properties of nanocomposite Nd2Fe14B/α-Fe magnetic alloys by a compositional adjustment, small amount of Dy and/or Co was added to Nd9Fe84B7 alloys. DTA analysis on the amorphous of the alloys took place as the soft magnetic phases were crystallized, and then the hard magnetic Nd2Fe14B was precipitated from them. While α-Fe and a metastable 1:7 (TbCu7-type) phase were formed simultaneously in Dy and Co-free alloys, they were crystallized separately at different temperatures after Dy or Co was added. This phase separation occurred more clearly in the Dy-treated alloys and the other soft magnetic phase Fe3B was also stabilized by Dy and/or Co. The 1: 7 phase that was stabilized by Dy and/or Co was not eliminated at 700 ℃, decreasing magnetic properties of the alloys. It was eventually disappeared above 725 ℃, but Fe3B was not eliminated even at 750 ℃ when Dy was added more than 0.5 at% or Co was added more than 2.0 at%. Amount of Nd2Fe14B in the alloys tended to increase as Dy addition increased,whereas Co addition did not lead to any appreciable change in the ratio of α-Fe and Nd2Fe14B. moreover, Dy addition apparently increased coercivity of an alloy while Co addition had a beneficial effect on remanence. The grains in the Dytreated alloys were usually finer than those in the Co-treated alloys. The grain size of both α-Fe and Nd2Fe14B in the alloys exhibiting mr ≥ 0.72 was in the range of 20 ～ 40 nm or even larger 50 nm, which is larger than the theoretical optimum size ( ～ 10 nm). Typical magnetic properties obtained from a Nd7.5Dy1.5Fe82.5Co1.5B7 alloy annealed for 12 min at 725 ℃were ihc=4.85 kOe, Br= 11.32 kG, (Bh)max = 15.73 mGOe, and mr=0.73.

关键词： nanocomposite Nd-Fe-B magnetic properties remanence coercivity

Dirac R-matrix calculations of photoionization cross sections of Ni Ⅻ and atomic structure data of Ni 

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Chinese Physics B 2017年第2期26卷 127-140页

作者： R T Nazirt m A Bari m Bilal s sardar m h Nasim m salahuddin Department of Physics and Applied mathematics Pakistan Institute of Engineering and Applied Sciences Islamabad 45650 Pakista

We performed R-matrix calculations for photoionization cross sections of the two ground state configuration 3s^23p^5（~2P_（3/2,1/2）~o） levels and 12 excited states of Ni Ⅻ using relativistic Dirac Atomic R-matrix Codes（DARC） across the photon energy range between the ionizations thresholds of the corresponding states and well above the thresholds of the last level of the Ni XIII target ion. Generally, a good agreement is obtained between our results and the earlier theoretical photoionization cross sections. moreover, we have used two independent fully relativistic GRAsP and FAC codes to calculate fine-structure energy levels, wavelengths, oscillator strengths, transitions rates among the lowest 48 levels belonging to the configuration（3s^23p^4, 3s3p^5, 3p^6, 3s^23p^33d） in Ni XIII. Additionally, radiative lifetimes of all the excited states of Ni XIII are presented. Our results of the atomic structure of Ni XIII show good agreement with other theoretical and experimental results available in the literature. A good agreement is found between our calculated lifetimes and the experimental *** present results are useful for plasma diagnostic of fusion and astrophysical plasmas.

关键词： photoionization cross sections energy levels wavelengths lifetimes

A New Process for Titanium Aluminides Production from TiO_2

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Journal of materials science & Technology 2007年第3期23卷 367-372页

作者： A.R.Kamali h.Razavizadeh s.m.m.hadavi Department of materials and metallurgy Engineering IUsT University Department of Chemical and materials Engineering maleke Ashtar University

This paper describes a new process for producing titanium aluminides, in particular TiAl, from TiO2 raw material. On the basis of obtained results, the non-completed reaction of TiO2 with Al and Ca in a special reaction vessel results in the production of granulates of titanium aluminides especially Ti3Al and other Ti- Al phases as the metallic product and Ca12Al14O33 as the non-metallic product. By adding KClO4 in the mixture, a nearly completed reaction can be carried out. The products of this reaction are titanium aluminide particularly TiAl as the metallic part and CaAl4O7 （grossite） as the non-metallic slag part. Both product and slag are produced in a separated form. This process, called KRh-method is described in this article. The scanning electron microscopic microstructure of metallic part of the product shows different phases： the matrix phase is TiAI, where the needle form precipitation is TiAl2 and the plate form precipitation includes TiAI and Ti3Al phases. The microstructure of the remelted metallic part indicates dendritic phase with a lamellar structure comprising of TiAl and Ti3Al phases. The interdendritic phase of TiAI is also seen.

关键词： Titanium aluminide Titanium dioxide Grossite KRh process

Investigation on the dissolution of η phase in a cast Ni-based superalloy

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International Journal of minerals,metallurgy and materials 2013年第1期20卷 42-48页

作者： m.R. Jahangiri h. Arabi s.m.A. Boutorabi school of metallurgy and materials Engineering Iran University of Science and Technology metallurgy Department Niroo Research Institute Center of Excellence for Advanced materials & Processing Iran University of Science and Technology

The dissolution behavior of rI phase has been investigated in a cast Ni-based superalloy. The results showed that the platelets and blocks of η phase were formed within the interdendritic regions of the microstructure. Applying standard solution annealing at 1150-1160℃ for a period of 4 h did not result in the complete dissolution of η phase. For the complete dissolution of η phase without residual incipient melting, a 2-step solution annealing has been recommended. After dissolution at high tem- peratures, the TI phase transforms to two mC-type carbides： one is enriched in Ti, Nb, and Ta, and the other is of （Zr,Ti）C type.

关键词： superalloys nickel alloys phase transitions dissolution heat treatment carbides

helically symmetric equilibria for some ideal and resistive mhD plasmas with incompressible flows

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Applied mathematics(A Journal of Chinese Universities) 2023年第2期38卷 192-209页

作者： s.m.moawad O.h.El-Kalaawy h.m.shaker mathematics and Computer science Department Faculty of ScienceBeni-Suef UniversityBeni-SuefEgypt Future high Institute of Engineering in Fyoum Ministry of High EducationFyoumEgypt

In this paper, the problem of finding exact solutions to the magnetohydrodynamic(mhD) equations in the presence of incompressible mass flows with helical symmetry is considered. For ideal flows, a similarity reduction method is used to obtain exact solutions for several mhD flows with nonlinear variable mach number. For resistive flows parallel to a magnetic field, the governing equilibrium equation is derived. The mhD equilibrium state of a helically symmetric incompressible flow is governed by a second-order elliptic partial differential equation(PDE) for the helical magnetic flux function. Exact solutions for the latter equation are obtained. Also, the equilibrium equations of a gravitating plasma with incompressible flow are derived.

关键词： magnetohydrodynamics helical symmetry resistivity incompressible ows exact equilibria

Improvement in mechanical Properties of microalloyed steel 30msV6 by a Precipitation hardening Process

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Journal of Iron and steel Research International 2013年第5期20卷 66-73页

作者： m hajisafari s Nategh h Yoozbashizadeh A Ekrami Department of materials Engineering Science and Research Branch Islamic Azad University Department of materials science and Engineering Sharif University of Technology

The microstructural evolutions and mechanical properties of vanadium microalloyed steel （30msV6） during precipitation hardening were studied. The effects of aging temperature and cooling rate on mechanical strength （yield strength and ultimate tensile strength） were similar. Increasing aging temperature or cooling rate firstly increased the mechanical strength of specimens up to their maximum values, which then decreased with further increase in aging temperature or cooling rate. microstructural evolutions revealed that cooling rate had significant effects on the pearlite interlamellar spacing and size of pre-eutectoid ferrite. Unlike the effect of austenitizing temperature, the pearlite interlamellar spacing and pre-eutectoid ferrite size were decreased by increasing the cooling rate from austenitizing temperature. According to the microstructural evolutions and mechanical properties, the optimal heat treatment process of microalloyed steel 30msV6 was austenitizing at 950 ℃ for 1 h, air cooling （3.8 ℃/s） and aging at 600 ℃ for 1.5 h. This optimal heat treatment process resulted in a good combination of elongation and yield strength.

关键词： microalloyed steel microstructure precipitation strength

Thickness-dependent mechanical properties of nacre in Cristaria plicata shell:Critical role of interfaces

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Journal of materials science & Technology 2020年第9期44卷 1-8页

作者： s.m.Liang h.m.Ji X.W.Li Department of materials Physics and Chemistry School of Materials Science and EngineeringKey Laboratory for Anisotropy and Texture of MaterialsMinistry of EducationNortheastern UniversityShenyang110819China

The thickness dependence of mechanical properties of nacre in Cristaria plicata shell was studied under three-point bending *** results show that the mechanical behavior of nacre exhibits a strong thickness *** bending strength firstly increases with the increase of specimen thickness and then becomes roughly constant as the thickness reaches a certain value of∼***,the mean value of work per unit volume increases constantly with increasing specimen thickness;meanwhile,the cracking mode changes from penetration into the platelets to deflection along the *** theoretical analyses indicate that the thickness-dependent mechanical properties of nacre are mainly caused by the variation in the number of inter-lamellar *** more the number of inter-lamellar interfaces is,the higher the strength and work of fracture of nacre under bending tests will ***,as the number of inter-lamellar interfaces reaches a certain value(e.g.,in the present specimen with 2.5mm thickness),the strength tends to remain constant,while the work of fracture still ***,the present research findings are expected to provide a valuable guidance for the interfacial design of nacre-like materials with high strength and toughness.

关键词： Cristaria plicata shell Nacre mechanical property Thickness Interface

A high-strength and high-toughness nacreous structure in a deep-sea Nautilus shell:Critical role of platelet geometry and organic matrix

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Journal of materials science & Technology 2021年第29期88卷 189-202页

作者： s.m.Liang h.m.Ji X.W.Li Department of materials Physics and Chemistry School of Materials Science and EngineeringNortheastern UniversityShenyang110819China state Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China Key Laboratory for Anisotropy and Texture of materials Ministry of EducationNortheastern UniversityShenyang110819China

To explore the differences in mechanical behavior of nacre between shells that live in different water depths,the microstructures,phase composition and related mechanical properties of nacre under indentation,three-point bending and shear tests in deep-sea Nautilus and freshwater Cristaria plicata shells were systematically *** is found that the nacreous structure in Nautilus shell exhibits an outstanding combination of high strength and high toughness compared with that in *** shell,attributing to its larger aspect ratio of platelet and interfacial shear ***,the interfacial resistance is mainly generated from the adhesion of organic matrix and friction caused by nano-asperities on platelet *** to the interfacial resistance model,the stiction force originated from organic matrix adhesion is sensitive to its content,and the friction force produced by nano-asperities presents a positive correlation with their distribution density and ***,the higher content of organic matrix of nacre with denser and larger nano-asperities on platelet surfaces in Nautilus shell contributes to a higher interfacial ***,it is the coupled effects of platelet geometries(*** ratio and nano-asperity)and organic matrix that result in the high-strength and high-toughness nacreous structure in Nautilus shell,which is thus more conductive to inhabit in the deep sea with extremely high *** present research findings are expected to provide beneficial references for the design of strong and tough nacre-inspired materials with appropriate platelet geometry and content of soft phase.

关键词： Deep-sea Nautilus shell Nacre mechanical property Platelet geometry Organic matrix

Effect of rare earth elements and their oxides on tribo-mechanical performance of laser claddings:A review

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Journal of Rare Earths 2016年第6期34卷 549-564页

作者： m.m.Quazi m.A.Fazal A.s.m.A.haseeb Farazila Yusof h.h.masjuki A.Arslan Department of mechanical Engineering Faculty of EngineeringUniversity of Malaya50603 Kuala LumpurMalaysia Center for Energy science Uni-versity of Malaya50603 Kuala LumpurMalaysia Centre of Advanced manufacturing and material Processing(AmmP Centre) University of Malaya50603 Kuala LumpurMalaysia

Laser cladding is a promising photon-based surface engineering technique broadly utilized for fabricating harder and wear resistant composite coatings. In spite of excellent properties, the practical applications of laser claddings are relatively restricted when compared with well-established coating techniques because of their inherent defects identified as cracks, pores and inclusions. substantial evidence suggests that the incorporation of an appropriate amount of rare earth in laser claddings can remarkably prevent these defects. Additionally, the presence of rare earth in laser claddings can notably enhance tribo-mechanical properties such as surface hardness, modulus of elasticity, fracture toughness, friction coefficient and wear rate. In this literature review, the effect of rare earth in reducing dilution and cracks susceptibility of laser claddings in addition to microstructural refinement attained was examined. mechanical and tribological properties of these claddings along with their underlying mechanism were discussed in detail. Finally, this article summarizes current applications of laser claddings based on rare earth and was concluded with future research directions.

关键词： laser cladding rare earth elements microstructure tribo-mechanical properties