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Journal of Advanced Ceramics 2014年第1期3卷 31-42页

作者： bahman nasiri-tabrizi Materials Engineering Department Najafabad BranchIslamic Azad UniversityNajafabadIsfahanIran

The influence of thermal treatment on the structural features of mechano-synthesized fluorapatite-titania composite nanopowders was studied.A mixture of calcium and phosphate reagents was mixed with a certain amount of titania(20 wt%)and then was mechanically activated for 5 h,10 h and 15 h *** that,the mechano-synthesized powders were annealed at 700℃for 2 *** crystallite size of the composite nanopowders estimated from Williamson-Hall method was in good agreement with transmission electron microscopy(TEM)*** electron microscopy(SEM)/TEM images confirmed the formation of a cluster-like composite which was composed of ellipse-like nanoparticles with an average size of about 16±7 nm after 15 h of *** the milling process,large variations in mechanochemical behavior of the CaHPO_(4)-Ca(OH)_(2)-CaF2-TiO_(2) system were *** the beginning of milling,no trace of the composite was found due to the lack of sufficient time for the mechanical *** the mechanical activation time increased to 15 h,composite nanopowders with the crystallite size of around 21.66 nm were *** heating at 700℃,the recovery of crystallinity occurred and the fraction of crystalline phase reached a maximum around 88.79%for the 10-h milled *** indicated that the structural features of the composite were strongly influenced by the subsequent annealing.

关键词： nanocomposite fluorapatite thermal treatment Williamson-Hall method structural features

Characterization of mechanothermal-synthesized hydroxyapatite-magnesium titanate composite nanopowders

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Journal of Advanced Ceramics 2013年第1期2卷 63-70页

作者： Abbas FAHAMI bahman nasiri-tabrizi Materials Engineering Department Najafabad BranchIslamic Azad UniversityNajafabadIsfahanIran

Hydroxyapatite-magnesium titanate composite nanopowders have been developed using a mechanothermal *** treatment of the milled powders at 700℃resulted in the formation of HAp/MgTiO_(3)-MgO nanocomposite.X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and energy dispersive X-ray spectroscopy(EDX)techniques were utilized to characterize the synthesized *** results revealed that the dominant phases after mechanical activation were hydroxyapatite,anatase(TiO_(2))and periclase(MgO);while after thermal annealing process at 700℃,hydroxyapatite along with geikielite(MgTiO_(3))and periclase(MgO)were the major *** on the XRD analysis,the evaluation of structural features of the samples indicated that the average crystallite sizes of hydroxyapatite after 10 h of milling and subsequent thermal treatment at 700℃were about 21 nm and 34 nm,*** observations illustrated that the synthesized powders contained large agglomerates which consisted of significantly finer particles with spheroidal *** is concluded that the mechanothermal method can be used to produce hydroxyapatite-based nanocomposite with appropriate structural and morphological features.

关键词： HAp/MgTiO_(3)-MgO nanocomposite characterization methods mechanothermal

Mechanochemical preparation and structural characterization of Ta-doped chlorapatite nanopowders

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Progress in Natural Science:Materials International 2016年第6期26卷 546-554页

作者： bahman nasiri-tabrizi Wan Jefrey Basirun Belinda Pingguan-Murphy Advanced Materials Research Center Materials Engineering DepartmentNajafabad BranchIslamic Azad University Department of Chemistry Faculty of ScienceUniversity of Malaya Department of Biomedical Engineering Faculty of EngineeringUniversity of Malaya

Nanocrystalline tantalum-doped chlorapatite（Ta-doped ClA） was successfully synthesized using a facile mechanochemical method. In the absence of the dopant, milling for 3 h led to the formation of a poorly crystalline hydroxyapatite, while in its presence of the Ta dopant, Ta-doped ClA nanopowders were produced as a result of an oncoming reaction. The results indicated that lattice micro-strain, crystallite size, crystallinity level, phase percentage and hexagonal lattice constants of the substituted apatite nanopowders were dramatically affected by the doping concentration. The a-axis and unit cell volume increased with the increase in the doping concentration, owing to the ionic radius difference of Cl;and OH;ions. From the TEM observations, the doped powders consisted of nanoneedles with a mean size of 60 ± 20 nm in length and 14 ±4 nm in width.

关键词： Mechano-synthesis Structural features Lattice constants XRD-Rietveld refinement Ta-doped ClA

Characterization of single-crystal fluorapatite nanoparticles synthesized via mechanochemical method

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Particuology 2011年第5期9卷 537-544页

作者： Reza Ebrahimi-Kahrizsangi bahman nasiri-tabrizi Akbar Cham Materials Engineering Department Najafabad Branch Islamic Azad University

The synthesis of nanostructured fiuorapatite （FA; Calo（PO4）6F2） was explored from the starting materials of CaHPO4, Ca（OH）2, CaO, P205 and CaF2 via a mechanochemical process. In this research, the suitability of using the mechanochemical process to prepare a high crystalline phase of FA was studied. The characterization and structural features of the synthesized powders were evaluated using powder X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FT-IR）, energy dispersive X-ray spectroscopy （EDX）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM） techniques. The results from the structural studies indicate that the maximum lattice disturbance in the apatite structure after the mechanochemical process was at the （0 0 2） plane. Furthermore, the maximum particle size was below the crystallite size after 60 h of milling and subsequent thermal treatment at 600 ℃ for 1 h （heated up to 600 ℃ and kept for 1 h at this temperature）. We determined that this method gives rise to the single-crystal FA with an average size in the range of 25 ± 5 to 29 ± 9 rim. The present findings suggest that the solid-state reaction and appropriate thermal process simultaneously lead to the formation of nanostructured FA with spheroidal shape.

关键词： Fluorapatite Single-crystal Nanoparticles Mechanochemical Crystallinity

Structural insights of mechanically induced aluminum-doped hydroxyapatite nanoparticles by Rietveld refinement

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Chinese Journal of Chemical Engineering 2017年第2期25卷 238-247页

作者： Abbas Fahami bahman nasiri-tabrizi Gary W. Beall Wan Jefrey Basirun Materials Science Engineering and Commercialization Program Texas State University San Marcos 78666 TX USA Advanced Materials Research Center Materials Engineering Department Najafabad Branch Islamic Azad University Najafabad lsfahan lran Department of Chemistry and Biochemistry Texas State University San Marcos 78666 TX USA Physics Department Faculty of Science King Abdulaziz University Jeddah 21589 Saudi Arabia Department of Chemistry Faculty of Science University of Malaya150603 Kuala Lumpur Malaysia

Aluminum doped hydroxyapatite （HA：AI3 ＋） nanopowders were successfully prepared via a simple and efficient one-pot mechanochemical route. The effects of dopant loading on phase compositions and structural features were assessed by Rietveld analysis. The XRD-Rietveld refinement revealed the stabilization of HA in hexagonal structure for all the samples. The sharpness and intensity of the apatite-derived XRD peaks decreased as the dopant content increased to 10% due to the increase in lattice imperfections and mechanically induced amorphization. The incorpo- ration of A13 ＋ into the HA lattice decreased the unit cell parameters. From the FfiR measurements, the representing bands of apatite were identified in all cases. The mechanosynthesized nanopowders consisted of nanospheroids with an average size of 44 - 20 nm and therefore are promising for bone tissue regeneration.

关键词： SynthesisIon exchangeMechanochemicalRietveld refinement

Structural Characterization of Nanocrystalline Ni(50-x)Ti50Cux(X = 5, 9 wt%) Alloys Produced by Mechanical Alloying

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Advances in Nanoparticles 2013年第2期2卷 71-77页

作者： bahman nasiri-tabrizi Abbas Fahami Materials Engineering Department Najafabad Branch Islamic Azad University Isfahan Iran

Nanocrystalline Ni(50-x)Ti50Cux(X = 5, 9 wt%) alloys were successfully produced by mechanical alloying. Mechanical activation was performed at different milling times under a high purity argon (99.998 vol%) atmosphere. Phase analysis and structural features of the samples were examined by X-ray diffraction (XRD). Results revealed that NiTiCu (B2) phase was achieved after 600 min of milling. The formation of this phase was mostly related to the critical factors in determining the site replacement of elements in Ni-Ti-Cu ternary system. After 600 min of milling, the average crystallite size and lattice strain of the samples were about 5 - 10 nm and 1.057% - 1.967%, respectively. Evaluation of the full width at half maximum (FWHM) values for all the samples indicated the occurrence of anisotropic line broadening. The determined amounts of crystallinity revealed that the fraction of crystalline phase decreased with increasing weight percentage of copper up to 9% and reached a minimum value after 600 min of milling. The lattice parameters and the unit cell volume of the milled samples were always larger than the standard values. In addition, lattice parameter deviation influenced by the weight percentage of copper. Based on the obtained data, mechanical alloying process can be used for production of nanocrystalline NiTiCu alloys with different structural features.

关键词： Nanocrystalline Alloy Mechanical Alloying Phase Analysis Structural Features

Progress in Thermomechanical Analysis of Friction Stir Welding

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Chinese Journal of Mechanical Engineering 2020年第1期33卷 11-43页

作者： bahman Meyghani Chuansong Wu Institute of Materials Joining Shandong UniversityJinan 250061China

This article reviews the status of thermomechanical analysis of the friction stir welding(FSW)process for establishing guidelines for further investigation,filling the available research gaps,and expanding FSW ***,the advantages and applications of FSW process are introduced,and the significance and key issues for thermomechanical analysis in FSW are pointed ***,solid mechanic and fluid dynamic methods in modeling FSW process are described,and the key issues in modeling FSW are *** erent available mesh modeling techniques including the applications,benefits and shortcomings are *** that,at different subsections,the thermomechanical analysis in FSW of aluminum alloys and steels are examined and summarized in ***,the conclusions and summary are presented in order to investigate the lack of knowledge and the possibilities for future study of each method and each material.

关键词： Thermomechanical analysis Friction stir welding Solid mechanic Fluid dynamic Mesh modeling techniques Aluminum alloys and Steels

Laser conditioning and structuring of grinding tools--a review

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Advances in Manufacturing 2017年第1期5卷 35-49页

作者： bahman Azarhoushang Ali Zahedi Institute of Precision Machining (KSF) FurtwangenUniversity of Applied Sciences Jakob-Kienzle-Strasse 1778054 Villingen-Schwenningen Germany

The conditioning of grinding tools is one of the most important factors for achieving an optimal grinding process. It influences the grinding forces and temperatures and, therefore, the achievable material removal rate, dimensional accuracy and the surface integrity of the workpiece. Furthermore, the roundness, profile accuracy and the wear of the grinding tools are strongly influenced by the conditioning process. The conditioning process should be matched to the abrasive type and the bonding of the grinding tool. Laser conditioning is a promising unconventional and non-contact method, which is able to condition all kinds of abrasives and bonding types. The main advantages of this novel method are no tool wear, good repeatability and controllability, high precision and a relatively short process time. Additionally, using this method, grinding tools can be micro-structured. This paper reviews the literature on the laser conditioning of grinding tools, covering the associated setups, wheel conditioning and structuring mechanisms, and experimental results. It also discusses the technical barriers that have to be overcome before laser conditioning can be fully integrated into manufacturing.

关键词： Laser conditioning Structuring Dressing -Truing Grinding tool. Grinding

Assessing dynamic response of multispan viscoelastic thin beams under a moving mass via generalized moving least square method

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Acta Mechanica Sinica 2010年第5期26卷 721-733页

作者： Keivan Kiani Ali Nikkhoo bahman Mehri Department of Civil Engineering Sharif University of Technology Department of Mathematical Sciences Sharif University of Technology

Dynamic response of multispan viscoelastic thin beams subjected to a moving mass is studied by an efficient numerical method in some detail. To this end, the unknown parameters of the problem are discretized in spatial domain using generalized moving least square method （GMLSM） and then, discrete equations of motion based on Lagrange＇s equation are obtained. Maximum deflection and bending moments are considered as the important design parameters. The design parameter spectra in terms of mass weight and velocity of the moving mass are presented for multispan viscoelastic beams as well as various values of relaxation rate and beam span number. A reasonable good agreement is achieved between the results of the proposed solution and those obtained by other researchers. The results indicate that, although the load inertia effects in beams with higher span number would be intensified for higher levels of moving mass velocity, the maximum values of design parameters would increase either. Moreover, the possibility of mass separation is shown to be more critical as the span number of the beam increases. This fact also violates the linear relation between the mass weight of the moving load and the associated design parameters, especially for high moving mass velocities. However, as the relaxation rate of the beam material increases, the load inertia effects as well as the possibility of moving mass separation reduces.

关键词： Moving mass-beam interaction - Multispan viscoelastic beam Euler-Bernoulli beam Generalized moving least square method (GMLSM)

Real-time assessment of tunnelling-induced damage to structures within the building information modelling framework

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Underground Space 2024年第1期14卷 99-117页

作者： Jelena Ninic Ali Gamra bahman Ghiassi School of Engineering University of BirminghamB152TTUK Centre for Structural Engineering and Informatics The University of NottinghamNG72RDUK

During the initial design phases of complex multi-disciplinary systems such as urban tunnelling,the appraisal of different design alternatives can ensure optimal designs in terms of costs,construction time,and *** enable the evaluation of a large number of design scenarios and to find an optimal solution that minimises impact of tunnelling on existing structures,the design and assessment process must be efficient,yet provide a holistic view of soil-structure interaction *** paper proposes an integrated tunnel design tool for the initial design phases to predict the ground settlements induced by tunnelling and building damage using empirical and analytical solutions as well as simulation-based meta ***,visualisation of ground settlements and building damage risk is enabled by integrating empirical and analytical models within our Building Information Modelling(BIM)framework for *** approach allows for near real-time assessment of structural damage induced by settlements with consideration of soil-structure interaction and non-linear material ***,because this approach is implemented on a BIM platform for tunnelling,first,the design can be optimised directly in the design environment,thus eliminating errors in data exchange between designers and computational ***,the effect of tunnelling on existing structures can be effectively visualised within the BIM by producing risk-maps and visualising the scaled deformation field,which allows for a more intuitive understanding of design actions and for collaborative *** a fully parametric design model and real-time predictions therefore enables the assessment and visualisation of tunneling-induced damage for large tunnel sections and multiple structures in an effective and computationally efficient way.

关键词： Building information modelling Soil-structure interaction Tunnelling Settlements Structural damage Visualisation Meta models