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Assessment of Sensitization in AISI 304 Stainless Steel by Nonlinear Ultrasonic Method

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Acta Metallurgica Sinica(English Letters) 2013年第5期26卷 545-552页

作者： Saju T.Abraham S.K.Albert C.R.Das N.Parvathavarthini B.Venkatraman R.S.Mini K.Balasubramaniam Quality Assurance division Indira Gandhi Centre for Atomic Research Department of mechanical Engineering Government Engineering College Department of mechanical Engineering Indian Institute of Technology

A nonlinear ultrasonic technique has been developed to evaluate sensitization in Type 304 stainless steel. In order to achieve diferent degree of sensitization（DOS）, specimens have been subjected to heat treatment at 675℃ at varying soaking time（0.5, 1.0, 2.0, 3.0 and 4.0 h）. Heat treated specimens were subjected to intergranular corrosion tests as per ASTM standards A262 and G108. Sensitization in longer soaked material has been confirmed through ditch microstructures, cracks on the bend tested specimens and higher degree of sensitization. Nonlinear ultrasonic studies showed variation in the nonlinearity parameter with soaking time which also confirms sensitization. A good correlation was observed between the degree of sensitization measured by the electrochemical potentiokinetic reactivation test and the ultrasonic nonlinearity *** study clearly demonstrated that nonlinear ultrasonic technique can be used as a potential technique for non-destructive characterization of sensitization in austenitic stainless steel.

关键词： Austenitic stainless steel Degree of sensitization Intergranular corrosion Nonlinear ultrasonics

Adaptive Neuro-Fuzzy Modeling of mechanical Behavior for Vertically Aligned Carbon Nanotube Turfs

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Journal of Materials Science & Technology 2011年第4期27卷 301-308页

作者： Mohammad Al-Khedher Charles Pezeshki Jeanne McHale Fritz Knorr Mechatronics division Al-Balqa Applied University School of mechanical and Materials Engineering Washington State University Department of Chemistry Washington State University

Several characterization methods have been developed to investigate the mechanical and structural properties of vertically aligned carbon nanotubes （VACNTs）. Establishing analytical models at nanoscale to interpret these properties is complicated due to the nonuniformity and irregularity in quality of as-grown samples. In this paper, we propose a new methodology to investigate the correlation between indentation resistance of multi-wall carbon nanotube （MWCNT） turfs, Raman spectra and the geometrical properties of the turf structure using adaptive neuro-fuzzy phenomenological modeling. This methodology yields a novel approach for modeling at the nanoscale by evaluating the effect of structural morphologies on nanomaterial properties using Raman spectroscopy.

关键词： Adaptive neuro-fuzzy Carbon nanotubes Image analysis Nanoindentation Raman spectroscopy

Formation and characterization of Plasma Sprayed Photocatalytic TiO2- ZnO Nano- Compounded Coatings

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Journal of Rare Earths 2004年第z2期22卷 162-166页

作者： Lee Soo Wohn Aum Ho Sung Hur Bo Young Chen Huang division of Materials and Chemical Engineering Sun Moon UniversityAsanChungnam 336708Korea Division of Mechanical and Control EngineeringSun Moon UniversityAsanChungnam 336708Korea Division of Materials EngineeringGyeong Sang National UniversityChinju 660701Korea Division of Materials and Chemical EngineeringSun Moon UniversityAsanChungnam 336708Korea

Two kinds of TiO2-ZnO nano-compounded powders aggregated by spray-drying process and evaporation method were used to deposit photocatalytic coatings by atmospheric plasma spraying technique. The phase compositions, morphologies of the agglomerated TiO2-ZnO powders and the as-sprayed coating were characterized using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) respectively. Furthermore, roughness measurements were carried out on their surfaces of the plasma sprayed TiO2-ZnO nano-comPounded coatings. Compared with the TiO2ZnO nano-compounded coating deposited from the spray-dried powder, it was found that the TiO2-ZnO nano-compounded coating deposited from the evaporated powder possesses higher anatase phase. It is ascribed to the existing of partially melted or non-melted microstructure in the TiO2-ZnO coating deposited from the evaporated powder. The partially-meltedor non-melted microstructure was retained from the starting agglomerated powder. This microstructure is beneficial to improve the photocatalytic properties of plasma sprayed TiO2-ZnO nano-compounded coatings.

关键词： plasma spraying spray-drying evaporation characterization TiO2-ZnO rare earths

Effect of tool plunge depth on reinforcement particles distribution in surface composite fabrication via friction stir processing

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Defence Technology（防务技术） 2017年第2期13卷 86-91页

作者： Sandeep Rathee Sachin Maheshwari Arshad Noor Siddiquee Manu Srivastava division of Manufacturing Processes and Automation Engineering(MPAE) Netaji Subhas Institute of Technology Department of mechanical Engineering Jamia Millia Islamia A Central University

Aluminium matrix surface composites are gaining alluring role especially in aerospace, defence, and marine industries. Friction stir processing(FSP) is a promising novel solid state technique for surface composites fabrication. In this study, AA6061/SiC surface composites were fabricated and the effect of tool plunge depth on pattern of reinforcement particles dispersion in metal matrix was investigated. Six varying tool plunge depths were chosen at constant levels of shoulder diameter and tool tilt angle to observe the exclusive effect of plunge variation. Process parameters chosen for the experimentation are speed of rotation, travel speed and tool tilt angle which were taken as 1400 rpm, 40 mm/min, and 2.5 °respectively. Macro and the microstructural study were performed using stereo zoom and optical microscope respectively. Results reflected that lower plunge depth levels lead to insufficient heat generation and cavity formation towards the stir zone center. On the other hand, higher levels of plunge depth result in ejection of reinforcement particles and even sticking of material to tool shoulder. Thus, an optimal plunge depth is needed in developing defect free surface composites.

关键词： Metal matrix composites Friction stir processing Tool plunge depth Microstructural characterization

Effects of charging rates on LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2)(NMC622)/graphite Li-ion cells

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Journal of Energy Chemistry 2021年第5期30卷 121-126页

作者： Xianyang Wu Yaocai Bai Zhenglong Li Jue Liu Kejie Zhao Zhijia Du Energy and Transportation Science division Oak Ridge National LaboratoryOak RidgeTN 37830USA School of mechanical Engineering Purdue UniversityWest LafayetteIN 47907USA Neutron Scattering division Oak Ridge National LaboratoryOak RidgeTN 37830USA

Enabling fast charging capability of lithium-ion battery is of great importance to widespread adoption of electric *** the charging rates from state-of-the-art 2 C(30 min)to 6 C(10 min)requires deep understanding on the cell aging *** this study,400 mAh pouch cells are cycled at 1 C,4 C and 6 C charging rates with 1 C discharging *** fading,cathode structural changes,Li inventory loss,electrolyte composition changes and Li plating on graphite electrodes are thoroughly studied by various characterization *** rapid capacity fading in cells at 6 C charging rate is mainly due to Li inventory loss from cathode structure and metallic Li plating on graphite electrode at higher charging ***-mortem analysis also revealed changes in electrolyte such as increased salt molarity and transesterification during fast charging.

关键词： Li-ion cells Fast charging Post-test analysis Neutron powder diffraction

Microstructure Evolution during Friction Stir Welding of Aluminum Alloy AA2219

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Journal of Materials Science & Technology 2010年第8期26卷 747-753页

作者： K.S.Arora S.Pandey M.Schaper R.Kumar mechanical Engineering Department Indian Institute of Technology Institut fuer Werkstoffwissenschaft Technische Universitaet Dresden Institut fuer Sicherheitsforschung Forschungszentrum Dresden-Rossendorf Engineering division National Metallurgical Laboratory

The characterization of microstructure evolution in friction stir welded aluminum alloy was carried out by optical microscopy （OM） and transmission electron microscopy （TEM） and electron backscatter diffraction （EBSD）. The weld nugget consisted of very fine equiaxed grains and experienced dissolution of nearly half of metastable precipitates into the matrix during welding. Thermomechanically affected zone （TMAZ） also experienced dissolution of precipitates but to a lesser extent whereas coarsening of precipitates was observed in heat affected zone （HAZ）. Grain boundary misorientation measurements using EBSD indicated continuous dynamic recrystallization as the underlying mechanism for the fine equiaxed nugget grains. The yield and tensile strength of the weld decreased with comparison to base material. But due to the decrease of grain size and the dissolution of second phase precipitates, an increased Charpy energy value was observed in the weld n u gget.

关键词： Friction stir welding AA2219 Precipitates Vickers hardness Tensile testing Charpy impact energy

characterization and Photocatalytic Efficiency of TiO_2 /Ti Beads Fabricated by Simple Heat-Treatment

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Journal of Materials Science & Technology 2012年第2期28卷 184-192页

作者： Altangerel Amarjargal Leonard D.Tijing Mi-Hwa Yu Chae-Hwa Kim Chan-Hee Park Dong-Won Kim Cheol-Sang Kim Department of Bionanosystem Engineering Chonbuk National University Power Engineering School Mongolian University of Science and Technology division of mechanical Design Engineering Chonbuk National University Department of Industrial and Information Systems Engineering Chonbuk National University

The goal of the present study was to investigate the photocatalytic efficiency of titanium dioxide （TiO2） formed on titanium （Ti） bead substrate （referred herein as TiO2/Ti beads） by heat treatment when exposing to ultraviolet （UV） light irradiation. Escherichia coli was used as the model test organism. The results show 4-log and 7-log decrease in bacterial concentration after a test time of 15 and 120 min, respectively, using TiO2/Ti beads irradiated with UV light in a tin-foil covered beaker. This article presents the potential of TiO2 on Ti bead substrate formed by simple heat-treatment together with UV light for bacterial inactivation.

关键词： Photocatalysis Titanium dioxide Bacterial inactivation Heat treatment Escherichia coli

Biomaterials / bioinks and extrusion bioprinting

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Bioactive Materials 2023年第10期28卷 511-536页

作者： X.B.Chen A.Fazel Anvari-Yazdi X.Duan A.Zimmerling R.Gharraei N.K.Sharma S.Sweilem L.Ning Department of mechanical Engineering University of Saskatchewan57 Campus DrS7K 5A9SaskatoonCanada b Division of Biomedical EngineeringUniversity of Saskatchewan57 Campus DrSaskatoonS7K 5A9Canada c Department of Mechanical EngineeringCleveland State UniversityClevelandOH44115USA

Bioinks are formulations of biomaterials and living cells, sometimes with growth factors or other biomolecules, while extrusion bioprinting is an emerging technique to apply or deposit these bioinks or biomaterial solutions to create three-dimensional (3D) constructs with architectures and mechanical/biological properties that mimic those of native human tissue or organs. Printed constructs have found wide applications in tissue engineering for repairing or treating tissue/organ injuries, as well as in vitro tissue modelling for testing or validating newly developed therapeutics and vaccines prior to their use in humans. Successful printing of constructs and their subsequent applications rely on the properties of the formulated bioinks, including the rheological, mechanical, and biological properties, as well as the printing process. This article critically reviews the latest developments in bioinks and biomaterial solutions for extrusion bioprinting, focusing on bioink synthesis and characterization, as well as the influence of bioink properties on the printing process. Key issues and challenges are also discussed along with recommendations for future research.

关键词： 3D bioprinting Extrusion Bioinks Biomaterials Tissue engineering

Synthesis of iron oxide nanoparticles via sonochemical method and their characterization

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Particuology 2011年第1期9卷 95-99页

作者： Amir Hassanjani-Roshan Mohammad Reza Vaezi Ali Shokuhfar Zohreh Rajabali Engineering Department Islamic Azad University Karaj Branch Karaj Iran division of Advanced Materials Materials and Energy Research Center Karaj Iran Advanced Materials and Nanotechnology Research Center Faculty of Mechanical Engineering K.N. Toosi University of Technology Tehran Iran

Preparation of iron oxide （α-Fe2O3） nanoparticles was carried out via a sonochemical process. The process parameters sucb as temperature, sonication time and power of ultrasonication play important roles in the size and morphology of the final products. The iron oxide nanoparticles were characterized by trans- mission electron microscopy, X-ray powder diffraction, and thermogravimetric and differential thermal analyses. From transmission electron microscopy observations, the size of the iron oxide nanoparticles is estimated to be significantly smaller than 19 nm. X-ray diffraction data of the powder after annealing provide direct evidence that the iron oxide was formed during the sonochemical process.

关键词： Sonochemical Nanoparticles Iron oxides Hematite