bluuebunny/crossref_metadata_2025 huggingface dataset:
High Precision Multiple Gas Mix & Distribution System for Mg-Alloy Smelting Protection Gas
Authors: Xie XiaoHao , Luo Qin , Dong Qing
Published: March 2009

The operating principle of and the calculating method of the key technology parameters of precise system for mixing the protecting gas of magnesium-Alloy smelting are described. This system adopts the “static-pressure mixing” technology, which has two gas vessels to provide the gas in turn. This technology, compared to the current “dynamic throttling commingle ” technology, enjoys higher
precision of mixing and stability of gas-providing. The economic precision of the mixing is 0.1 percent, which can obviously reduce of the commingling-ratio density of the valid elemental gas’ component and the operating cost of the equipment on the basis of ensuring the safety of segregation the oxygen during the magnesium- alloy smelting.
Effect of Strong Magnetic Field on the Discontinuous and Continuous Precipitation in AZ91 Mg Alloy
Authors: Dong Jie , Li Z.F. , Zeng Xiao Qin , Lu Chen , Ding Wen Jiang
Published: March 2009

A strong static magnetic field (SSMF) of about 10 T was introduced to the aging process of AZ91 magnesium alloy. Comparing with conventional aging, in the first stage of aging with SSMF, discontinuous precipitation of Mg17Al12 at grain boundary was accelerated. The magnetically induced grain boundary migration might be responsible for this acceleration effect. The density of the Mg17Al12 continuous precipitates inside the grains was increased and the precipitation plates became thinner in SSMF pre-aged specimens, which might be ascribed to the retarded volume diffusion resulted from the SSMF.
On Specific Features of Operating Crucibleless Salt-Bath Furnaces
Authors: Zabyelin I.V. , Komelin Igor M. , Barannik Ivan A. , Sikorskaya I.L.
Published: March 2009

This paper covers information on salt melts, used in crucibleless electrical furnaces as a heating element, which interact with atmospheric air to form solid and gaseous products and mostly determine the furnace design, governing furnace maintenance conditions and its service life.
Microstructure and Fracture Surfaces of Carbon Nanotubes/Magnesium Matrix Composite
Authors: Li Sinian , Song Souzhi , Yu Tianqin , Zhang You Shou , Chen Hong
Published: March 2009

Using carbon nanotubes (CNTs) as reinforced phase, it was made to carbon
nanotubes/Magnesium matrix composite by the foundry method in Argon gas protection. The experiment results show that CNTs can strengthen the mechanical properties of the CNTs/Magnesium matrix composite, and tensile strength and elongation ratio are greatly improved. Furthermore, the plating CNTs are better than un-plating CNTs in strengthening effects. Additionally the quantity of CNTs can not be too great, or the properties will be descended to a great extent without distraction of CNTs. Tensile strength has been higher by 150 % and the elongation ratio is higher by 30 % than matrix’s at best, and the fracture of the composite sample has a character of dimples.
An Analysis of the Development and Applications of Current and New Mg-Al Based Elevated Temperature Magnesium Alloys
Authors: Yang Ming Bo , Pan Fu Sheng , Zhang Jing , Zhang Jin
Published: March 2009

The current status of research and application in the AZ(Mg-Al-Zn), AS(Mg-Al-Si), AE(Mg-Al-RE), AX(Mg-Al-Ca), ACM or MRI（Mg-Al-Ca-RE）and AJ（Mg-Al-Sr）series elevated temperature magnesium alloys are reviewed, will special attention paid to the effects of alloying elements and the control of second phases. The existing problems on the development of elevated temperature magnesium alloys are discussed.
Reduce the Residual Stress of Welded Structures by Post-Weld Vibration
Authors: Rao De Lin , Zhu Zheng Qiang , Chen Li Gong , Ni Chunzhen
Published: March 2009

The existence of residual stresses caused by the welding process is an important reason of cracking and distortion in welded metal structures that may affect the fatigue life and dimensional stability significantly. Heat treatment is one of the traditional methods to relieve the residual stresses. But it is often limited by the manufacturing condition and the size of the structures. In this paper a procedure called vibratory stress relief (VSR) is discussed. VSR is a process to reduce and re-distribute the internal residual stresses of welded structures by means of post-weld mechanical vibration. The effectiveness of VSR on the residual stresses of welded structures, including the drums of hoist machine and thick stainless steel plate are investigated. Parameters of VSR procedure are described in the paper. Residual stresses on weld bead are measured before and after VSR treatment by hole-drilling method and about 30%~50% reduction of residual stresses are observed. The results show that VSR process can reduce the residual stress both middle carbon steel (Q345) and stainless steel (304L) welded structures effectively.
Measurement of Stress Distribution Near Fatigue Crack in Ultra-Fine Grained Steel by Synchrotron Radiation
Authors: Akiniwa Yoshiaki , Tanaka Keisuke , Kimura Hidehiko
Published: March 2009

Single-edge-notched specimens of ultrafine-grained steel were fatigued. The mean grain size of the steel is about 2 micrometers. Propagation behavior of fatigue cracks was observed with the crack closure. The resistance of the crack propagation of ultrafine-grained steel was larger than that of conventional steels. The crack closure acted as an important role for the larger resistance of fatigue crack propagation. After fatigue tests, stress distribution near the fatigue crack was measured by monochromatic X-rays from synchrotron radiation. The irradiated area was 100 µm x 100 µm. Residual and loading stress distributions ahead of the crack tip and on the crack wake was measured at the maximum stress intensity factor and zero applied load. The stress was determined by sin2ψ method. The measured stress was compared with the value calculated by FEM and the fatigue crack propagation model. The stress distribution at the maximum load and residual stresses agreed very well with the calculated results. The crack opening stress calculated by the residual stresses agreed with the experimental result.
Stresses Evaluation by Transmission Energy Dispersive X-Ray Diffraction Using Industrial Radiography Equipment
Authors: Lavelle Bruno , Vendier L. , Auriol O.
Published: March 2009

X-rays transmission stress analysis was tested on a 2mm thick steel sheet using energy dispersive X-rays diffraction (EDXD) and an industrial radiography equipment as X-ray source. A complex state of residual stresses was created in the sheet before the test and modified during the experiment by the way of a in-situ tensile test. In the diffracted beam spectrum, the energy peak displacement was related to macroscopic stresses using the elementary Mohr’s circle formalism for
plane stress analysis. The change in the stresses thus analyzed is compared with the applied stress.
A New Type of Instrument with Its Special Excited Input-Signal in Inspecting Residual Stress
Authors: Huang Gang , Li Lu Ming , Cao Yi Ping , Chen Xing
Published: March 2009

The issue of nondestructive testing in aeronautical structures is of considerable importance in the aviation industry today. And a high sensitivity magnetic field sensor, which has recently been developed is designed for non-destructive stress
testing. It is based on idea of the magnetic field produced by pulsed currents and
perturbed by the presence of stress. The sensor can be effectively utilized for the
detection of defects and stress concentration in conducting materials using eddy
current testing measurements. The principle of the measuring technique is based on the unbalance of the magnetic field where the stress or cracks exist. Also, the excited input-signal is special designed. A pulsed current was inputted and changed into a self-attenuation signal which does the effect in the probe.
Ultrasonic Evaluation of Compressive Residual Stress of Surface Treated Metals
Authors: Belahcene Farid , Zhou Xiaolai , Lu Jian
Published: March 2009

Shot peening is an effective method of improving fatigue performance of machine parts in the industry by producing a thin surface layer of compressive residual stresses that prevents crack initiation and retards crack growth during service. Nondestructive evaluation of the prevailing compressive residual stresses in the shallow subsurface layer is realized by the critically refracted longitudinal (Lcr) waves. This paper presents experimental data obtained on SMAT (surface mechanical attrition treatment) steel alloy S355 sample. Comparative travel-time shows that there are statistically significant differences in treated and untreated specimen. With knowledge of the acoustoelastic constants which are obtained by a test calibration, the experimental data indicates that compressive residual stresses are distributed near subsurface (hundreds of micron). These stress results show that the Lcr technique is efficient for evaluation of residual stresses after the surface
treatment.
Residual Stress Measurements in Australia: Present and Future
Authors: Curfs C. , Kirstein Oliver , Studer Andrew , Blevins R. , Carr David G. , Ripley Maurice I.
Published: March 2009

The Australian Nuclear Science and Technology Organisation, ANSTO,
(http:\\www.ansto.gov.au) has initiated a “Neutrons for Engineering” project to provide an integrated residual stress service to Australian industry and academia. The service is based around measurements of residual stress using neutrons on a newly-refurbished instrument on the HIFAR research reactor. In addition to the neutron measurements there is a range of expertise available on the ANSTO site to solve residual stress problems using other techniques including hole-drilling, strain-gauging, and x-ray diffraction, as well as capabilities for finite element modeling and
mechanical testing. In this paper we describe briefly the existing and future facilities at ANSTO for neutron strain scanning and present some benchmark results for the HIFAR strain scanner.
Internal Stress Measurement of Fiber Reinforced Composite by Neutron Diffraction with In Situ Low Temperature Stress Measurement System
Authors: Masayuki Nishida , Muslih M.Refai , Ikeuchi Yasukazu , Minakawa Nobuaki , Takao Hanabusa
Published: March 2009

The internal stresses in the continuous tungsten-fiber reinforced copper-matrix composite were examined by the Neutron stress measurement method. The Neutron diffraction apparatus ND1, which is abbreviated from the Neutron Diffraction system No.1 designed and manufactured by the National Nuclear Energy Agency in Indonesia (Badan Tenage Nuklir Nasional, BATAN), was used in the present study. The most common 3-axes measurement method with Hooke’s equation was
only possible to measure about 110 plane, because the tungsten fiber became the situation of heavy 110 orientation. Thermal stress alterations caused form low temperature cycling was measured by in-situ stress measurement method making use of a cryostat system. The thermal residual stresses in tungsten-fiber longitudinal direction were compressive state in every stage. Results of in-situ thermal stress measurement were good agreed with a calculated result of simple elastic theory in
elastic area.
Approach of Residual Stress Generated by Deep Rolling Application to the Reinforcement of the Fatigue Resistance of Crankshafts
Authors: Galzy F. , Michaud H. , Sprauel Jean Michel
Published: March 2009

In the new types of diesel motors, the crankshaft loads increase dramatically. For that reason, to satisfy the requirements and needs of its motorist’s customers, ASCOMETAL has developed a special bending fatigue test applied to “Baldwin” specimens reinforced by deep rolling. Such test is representative of the main in-service loads existing in crankshaft crankpin fillets (one of the weakest point of the component). Thus, using this test, the mechanisms leading to the increase of the fatigue resistance brought by the deep rolling treatment, could be identified. This
reinforcement is mainly linked to crack arrest due to both a decrease of the in-depth stress concentration factor and to remaining compressive residual stresses induced by the deep rolling. In this paper, the experimental methods (in particular X-rays diffraction) used to characterize the stress fields generated by the deep rolling treatment are described first. The equations of equilibrium and compatibility of the particular toric symmetry of the crankshaft crankpin fillets have been used then
to analyze the surface and in-depth stress profiles of the tested sample. This allowed characterizing the shake down and stress relaxation induced by fatigue. The crack propagation behaviour and the associated fracture limits were also defined.
Residual Stress Relaxation and Cyclic Deformation Behavior of Deep Rolled AlMg4.5Mn (AA5083) at Elevated Temperatures
Authors: Juijerm P. , Altenberger I. , Noster U. , Scholtes Berthold
Published: March 2009

The cyclic deformation behavior of deep rolled and polished aluminium wrought alloy
AlMg4,5Mn in the temperature range 20-300°C has been investigated. Results of quasistatic tension and compression tests of untreated specimens in the temperature range 20-300°C are presented. To characterize the fatigue behavior for stress-controlled tests as a function of test temperature, s-n curves, cyclic deformations curves and mean strains as a function of number of cycles are given. The residual stress- and work hardening states near the surface of deep rolled aluminium alloy AlMg4.5Mn before and after fatigue tests were investigated by X-ray
diffraction methods. The investigated AlMn4.5Mn aluminium alloy shows cyclic hardening until fracture at all stress amplitudes in stress-controlled fatigue tests at 25-150°C. With increasing temperature the deformation behavior shifts from cyclic hardening to cyclic softening. Below a certain stress amplitude at a given temperature deep rolling led to a reduction of the plastic strain amplitude as compared to the untreated state through cyclically stable near-surface work hardening as indicated by stable FWHM-values. This reduction in plastic strain amplitude is associated with enhanced fatigue lives. The effectiveness of deep rolling is governed by the cyclic and thermal stability of nearsurface work hardening rather than macroscopic compressive residual stresses. Since nearsurface work hardening is known to retard crack initiation, deep rolling is also effective in temperature- and stress ranges where macroscopic compressive residual stresses have relaxed almost completely, but where near-surface work hardening prevails.
Above certain stress amplitudes and temperatures, deep rolling has no beneficial effect on the fatigue behavior of AlMg4.5Mn. This is a consequence of instable near-surface microstructures, especially instable near-surface work hardening.
Influence of Transformation Plasticity on Residual Stresses and Distortions due to the Heat Treatment of Steels with Different Carbon Content
Authors: Franz Clemens , Besserdich Gerhard , Schulze Volker , Müller Hermann , Löhe Detlef
Published: March 2009

The field of heat treatment of steels offers a large variety of applications for the use of simulation tools. It always includes the development of residual stresses and distortions. The geometry of the part, the composition of the material, the heat treatment process as well as the initial state of the part interact with each other in complex ways and have an influence on the distortion of the part. Using simulation the temporal development of temperature, phases, stresses and distortions while quenching as well as the residual stress distribution and distortion after quenching can be calculated. Transformation plasticity has been proved to be very important for heat treatment simulation. Three steels with identical contents of alloying elements but different carbon contents of 0.2, 0.5 and 0.8 wt. % were analysed. The influence of transformation plasticity during the martensitic transformation on the distortions and residual stresses after quenching of cylinders made out of the three steels was analyzed in simulations and compared to experimental results.
Analysis of Residual Stress Influencing on Safety of Steam Turbine
Authors: Ding Changfu , Tian Song Feng , Wan Kuifang , Sun Li
Published: March 2009

With the coal-fired units developing toward large capacity and high parameter, the safety and the economic operation is very important. The cracks on the cylinder and rotor that produce during performance are analyzed. It is pointed out that residual stress is an important factor affecting the fault and should be noticed in practice. And residual stress monitoring online has good prospects of development in this field.
Determination of Residual Stress Gradients in Al2O3 Ceramics after Thermal and Mechanical Loading
Authors: Erbacher T. , Ott Michael , Beck Tilmann , Vöhringer Otmar
Published: March 2009

Al2O3 ceramic plates of diameter 166 mm and thickness 5 mm were subjected to frictional loading regimes. The resultant residual stress effect in the material was analyzed using the sin2y and AP methods based on a modified measurement condition for the pole angle y and the azimuth angle F on a 4 cycle goniometer. Furthermore, the frictional loading of the Al2O3 plates lead to clear differences in the residual stress state near the surface. An underlying correlation was observed
between the residual stress state of the Al2O3 material and its residual strength with this effect being ascribed to the magnitude of frictional load applied.
Modification of Alumina Ceramics Properties by Stressonic® Shot Peening
Authors: Tomaszewski Henryk , Godwod K. , Diduszko Ryszard , Carrois F. , Duchazeaubeneix J.M.
Published: March 2009

Modification of material surface layers by conventional shot peening is commonly used to improve the strength of metal components. As it occurred high compressive stresses up to 2.0 GPa may be introduced also to near surface region of alumina ceramics by this technique. Two alumina ceramics were given to ultrasonic shot peening which is a new, compact and small consuming of shot media method developed by Sonats company. This process is named Stressonic®. The dependence between diameter of tungsten balls, treatment time (at constant mass
of balls in the housing and vibration amplitude) and level of compressive stresses introduced was determined. High microplastic deformation in shot peened surface layer of alumina was observed by X-ray diffraction. An increase of surface resistance to fracture of ceramics with increasing level of compressive stresses was also found.
Residual Stresses in Bulk Metallic Glasses due to Thermal Tempering
Authors: Aydiner Cahit Can , Üstündag Ersan
Published: March 2009

Bulk metallic glasses (BMGs) are attractive structural materials that develop residual stresses during processing due to thermal tempering. In this process, compressive surface stresses are generated within thin layers balanced with tension in the interior. In the present study, stress generation was analyzed experimentally and theoretically in a BMG plate and a cylinder. The residual stresses were measured using the crack compliance method. It was shown that high
stresses can be attained in metallic glasses due to thermal tempering: over −300 MPa compression on the surface balanced by +150 MPa tension in the middle. The experimental data were then compared to the predictions of a viscoelastic model that took into account the equilibrium viscosity of BMG as a function of temperature. The model was shown to be accurate within 5 to 25% of the experimental stress data. It is therefore a powerful tool for estimating processing-induced residual stresses in bulk metallic glasses.
Generation of Nanostructures on 316L Stainless Steel and Its Effect on Mechanical Behavior
Authors: Roland T. , Retraint Delphine , Lu K. , Lu Jian
Published: March 2009

Improved mechanical behavior of surface nanostructured metallic materials produced by means of a surface mechanical attrition treatment (S.M.A.T) is investigated experimentally. Based on microscopic observations and residual stress measurements, factors leading to the high strength and yielding are discussed. The effects due to treatment, as compressive residual stresses, are in that way studied for a better understanding of their influence on the global mechanical response of the
nanostructured material. In regards of this, a simple way to increase the ductility of such a nanostructured material is also presented.
Spalling Stress in Oxidized Thermal Barrier Coatings Evaluated by X-Ray Diffraction Method
Authors: Suzuki Kenji , Tanaka Keisuke
Published: March 2009

The spallation of thermal barrier coatings (TBCs) is promoted by thermally grown oxide (TGO). To improve TBCs, it is very important to understand the influence of TGO on the spalling stress. In this study ,the TBCs were oxidized at 1373 K for four diferent periods: 0, 500,1000 and 2000 h. The distribution of the in-plane stress in oxidized TBCs, s1, was obtained by repeating the X-ray stress measurement with low energy X-rays after successive removal of the surface layer. The distribution of the out-of-plane stress, s1− s3, was measured with hard synchrotron X-rays, because high energry X-rays have a large penetration depth. From the results by the low and high energy Xrays, the spalling stress in the oxidized TBCs, s3, was evaluated. The evaluated value of the spalling stress for the oxidized TBC was a small tension beneath the surface, but steeply increased near the interface between the top and bond coating. This large tensile stress near the interface is responsible
for the spalling of the top coating.
Evaluation of Residual Stress in Nano-TiO2 Film on ITO Glass by Synchrotron X-Ray Diffraction
Authors: Ju Dong Ying , Ueda T. , Hatakeyama Tetsuo , Arizono T. , Kusaka Kazuya , Takao Hanabusa
Published: March 2009

In this study, evaluation of residual stress in nano-TiO2 film on ITO glass is carried
out. The films with thickness less than 30 nm are prepared by the dual-arcs magnetron sputtering with gas pressure 10 and 20 Pa. The surface microstructure and grain morphology of the nano-TiO2 films are observed by the atomic force microscopy (AFM). In order to accurately evaluate the residual stress in the film, the Young’s modulus of the film is determined by the nanoindentation with three point bending method at first, then the internal residual stress in the film is measured by high energy X-ray diffraction with the synchrotron radiation facility Spring-8. The measured residual stresses of nano-TiO2 films prepared with gas pressure 10 and 20 Pa are -11.6 and -9.1 GPa, respectively. It is shown that the residual stress of TiO2 films decrease with the increasing of gas pressure.
Application of the White/Monochromatic X-Ray μ-Diffraction Technique to the Study of Texture and Triaxial Strain at the Submicron Level
Authors: Goudeau Philippe , Tamura Nobumichi , Spolenak R. , Padmore H.A.
Published: March 2009

A scanning X-ray microdiffraction beamline using white or monochromatic beam has been recently made available to the user’s community at the Advanced Light Source, Berkeley, USA. Samples are scanned under an X-ray beam with size ranging from 15 microns down to less than a micron, and 2D diffraction patterns are collected at each step. A specifically written software allows for the full treatments
of these patterns to obtain as outputs high spatial resolution grain orientation, strain/stress or mineral species distribution maps. The range of applications of this technique goes from the study of the mechanical properties of thin films to the understanding of trace elements speciation in environmental sciences.
Recent Development in Nano and Graded Thermoelectric Materials
Authors: Zhang Qing Jie , Tang Xin Feng , Zhai Peng Cheng , Niino Masayuki , Endo Cyoji
Published: March 2009

In 2003, a joint research project entitled “Nano and graded thermoelectric
materials/Photovoltaic-thermoelectric-wind power generation” is established in cooperation among research institutes from Japan and China. The major research institutes include State Key Laboratory of Advanced Technology for Materials Synthesis and Processing (Wuhan University of Technology, China), Shanghai Institute of Ceramics (Chinese Academy of Sciences, China), State Key Laboratory of New Ceramics and Fine Processing (Tsinghua University, China), Japan Aerospace Exploration Agency (JAXA, Japan) and Foundation for Promotion of Japanese Aerospace Technology (JAST, Japan). The main aim of this project is to develop a photovoltaic-thermoelectric-wind power generation system with high efficiency solar energy conversion. The key works of the project include: (1) fabrication of high efficiency nano thermoelectric materials with a maximum figure of merit Z≥1.3; (2) design and fabrication of nano graded thermoelectric material/component with efficiency conversion larger than 12% for wide temperature range and (3) design and construction of photovoltaic- thermoelectric coupled power generation system. The recent progress about the joint research project is reported in this paper. Emphasis is put on the mechanism, design and fabrication of high efficiency nano graded thermoelectric materials. The future research plan is also mentioned in brief.
Corrosion Resistance of Homogeneous and FGM Coatings
Authors: Malinina Marina , Sammi Tina , Gasik Michael M.
Published: March 2009

Homogeneous and FGM environmental barrier coatings (EBC) made of alumina – NiCr on the steel substrates by high-velocity oxygen fuel (HVOF) spraying technique were studied. At room temperature, these coatings were characterized by DC polarization measurements and by electrochemical impedance spectroscopy (EIS) after various exposure times in highly aggressive basic solutions. At high temperatures (400-750°C) corrosion resistance was tested in respect to sulfide – sulfate – chloride – carbonate melts in air, which simulates environments in incinerators, kraft recovery boilers and turbines. After testing, the samples were examined by SEM and EDS and their corrosion resistance was compared.
The Optimization of Propagation Characteristic of Elastic Wave in FGM
Authors: Liu Li Sheng , Zhang Qing Jie , Zhai Peng Cheng
Published: March 2009

The reflected coefficient of functionally graded layer to waves is very important as the design of impact-resistant FGMs. In the paper, the Optimization problem of propagation characteristic of elastic wave in FGM has been investigated. The relation between the top layer’s stress and displacement and the bottom layer’s is deduced from elastic propagation equation as the incident wave is a plane and harmonic elastic stress wave, then the reflected coefficient of gradient layer is obtained, and the reflected coefficient is selected as object function of optimization. The thickness of each layer is selected as optimization design parameter. The conjugate gradient method is used to get the optimal results about gradient layers’ thickness.
Fracture and Fatigue Crack Propagation in Graded Composites
Authors: Tilbrook Matthew , Rutgers Lyndal , Moon Robert J. , Hoffman Mark
Published: March 2009

The propagation of cracks in graded materials under monotonic and cyclic loading was investigated via experiment and simulation. Graded alumina/epoxy composite specimens exhibiting a variation in composition from 5% to 65% epoxy, representing a twenty-fold variation in Young’s modulus, across a region of width between 6 and 20 mm, were produced by a multistep infiltration technique. Crack initiation and propagation under monotonic and cyclic four-point bend loading was monitored and crack trajectories and growth rates were measured. Initial crack deflection was observed, in agreement with theoretical and computational predictions in the literature. Cracks exhibited further deviation as they traversed the graded region. Higher deflection angles were observed for specimens with steeper gradients, and for those with cracks initially located closer to the compliant side of the gradient. Homogeneous specimens in the composition range 5% to 55% epoxy were also produced to investigate the composition dependence of mechanical, fracture and fatigue properties for aluminaepoxy composites. Crack propagation resistance appeared to differ between monotonic and cyclic loading, though an increase with crack extension was observed in both cases. The significant variation in measured crack-propagation resistance, for cracks in graded specimens, was accordingly interpreted as a combination of crack-extension effect and spatial variation of both intrinsic and extrinsic crack-growth resistance. A finite element model has been developed to simulate the propagation process, with particular attention paid to crack propagation and deflection criteria. Results from homogeneous specimens were utilised for estimating spatial property distribution and crack-extension effects in the graded specimens. Experimental results for crack path and crack-growth resistance profile show good agreement with modeling predictions.
Determining the Elastic Moduli of the Individual Component Layers of Cylindrical Thermal Barrier Coatings by Means of a Mixed Numerical - Experimental Technique
Authors: Lauwagie T. , Lambrinou K. , Mircea Iulian , Bartsch Marion , Heylen W. , Van der Biest Omer
Published: March 2009

Cylindrical specimens made of the Ni-based super-alloy Inconel 625 (IN 625) were coated with (a) NiCoCrAlY, or (b) NiCoCrAlY and yttria-stabilised zirconia (YSZ: in this case, zirconia with 7-8 wt% yttria), using the electron beam - physical vapor deposition (EB-PVD) technique. In the bi-layer coatings, the YSZ layer is the thermal barrier coating (TBC) and the NiCoCrAlY layer is the metallic bond coat (BC). The BC improves the bonding between the substrate and the ceramic TBC, while the low thermal conductivity of the TBC oers high-temperature protection to the substrate. This paper focuses on the determination of the elastic moduli of the substrate and the coating layers of the test samples. The elastic moduli
of the three dierent materials (IN 625, NiCoCrAlY and YSZ) were determined by means of a mixed numerical - experimental technique (MNET). The employed MNET was based on the comparison of the experimentally measured resonant frequencies of the rst bending mode of the test samples to the numerically calculated ones. The unknown elastic properties were determined by ne-tuning the elastic material parameters of the numerical models so as to enable the reproduction of the experimentally measured resonant frequencies.
Graded Microstructure at Fiber / Copper Matrix Interface in FRM Fabricated by the Reaction at Narrow Holes Method
Authors: Tanaka Yasuhiko , Goto Takeshi , Watanabe Yoshimi
Published: March 2009

The reaction at narrow holes method (RANH method) has been proposed for fabricating fiber reinforced metal (FRM), such as an intermetallic compound fiber / metal matrix composite. This study clarifies a microstructure at a fiber / metal matrix interface of FRM fabricated by using a combination of pure-copper and pure-aluminum in the RANH method. Pure-aluminum fiber was inserted into a narrow hole drilled in the copper matrix. The assembly comprising the pure-aluminum fiber and the pure-copper matrix was heated to a temperature greater than eutectic temperature of the copper-aluminum binary alloy. A molten aluminum reacted with copper to form an annular reacted region consisting of g1 intermetallic compound in a single phase near the edge of the narrow hole. The g1 intermetallic compound has very high hardness on the order of 800-900 HV. The annular reacted region may have a high tensile strength and may work as a reinforcing metal fiber in FRM.
Fabrication and Characterization of Porous Alumina Tube with Pore Gradient
Authors: Chen Chun Hong , Takita K. , Ishiguro Satoshi , Honda Sawao , Awaji Hideo
Published: March 2009

The porous alumina tube with pore gradient along the radial direction was successfully fabricated, where PMMA particles were used as pore former agent. The specimen was expected as a filter subjected to high temperatures. Alumina and PMMA particle were mixed with water to form aqueous slurry, compacted using centrifugal molding technique. The green body was dried in partial vacuum atmosphere, calcinated at 273 K to remove the organic component, sintered at 1623 K to obtain sintered porous a-alumina tubes. The control on the pore gradient of porous tubes was attempted by two ways; lamination and continuous methods. The microstructure observation showed that the inner part of the tubes had higher porosity than the outer part irrespective of the method used. Porous alumina tubes were characterized by microstructure observation, porosity and air permeability. The binary pores of 10µm and submicron in diameter were visible, which were formed by the burning-out PMMA particles and lower sintering temperature, respectively. The influence of PMMA amount on the pore morphology of the tubes was investigated. Fracture strength was carried out by the O-ring diametral compression testing. An analytical formula subject to the diametral testing was introduced with considering the porosity gradient. The correlations between the fracture strength and pore gradient were investigated, where a reduction in fracture strength was observed with the increase in laminated layers, and minimum strength was found in continuous porous tubes.
Synthesis and Characterization of III-V Rod Shape Semiconductor Nanocrystals
Authors: Nedeljković J.M. , Mićić O.I. , Ahrenkiel S.P. , Nozik A.J.
Published: March 2009

InP and InAs quantum rods were synthesized via the reactions of monodispersed indium droplets with phosphide or arsenide ions, respectively. In these reactions indium droplets, which do not act as a catalyst but rather as a reactant, are completely consumed. For the synthesis of InP and InAs quantum rods with a narrow size distribution, a narrow size distribution of indium particles is required because each indium droplet serves as a template to strictly limit the lateral growth of individual InP or InAs nanocrystals. Free-standing InP (130 Å diameter and 870 Å length) and InAs (180 Å diameter and 745 Å length) quantum rods without residual metallic catalyst at the rod tip were synthesized from the diluted transparent solutions of metallic indium. Both kinds of synthesized nanorods are in the strong confinement regime since the Bohr diameters of InP and InAs are 200 and 700 Å, respectively.
Role of Organic Additives in Hydriding Properties of Mg-C Nanocomposites
Authors: Montone Amelia , Grbović Novaković Jasna , Bassetti A. , Mirenghi L. , Rotolo P. , Bonetti Ennio , Pasquini Luca , Vittori Antisari Marco
Published: March 2009

The hydrogen storage performances of Mg-C nanocomposites have been studied on
materials synthesized by ball milling with and without addition of an organic additive. The main purpose of this work is to study in more detail the cooperative effect observed when both graphite and benzene are added to the milled blend. In fact, when both components are added to Mg in the ball milling process, good catalyzing properties of the composite surface allow improved sorptiondesorption behavior of the synthesized material. The processed materials have been characterized by XRD to assess the details of the phase structure by Rietveld analysis, while surface features have been studied by XPS, which evidences structural modifications of both the surface Mg oxide and the graphite particles. The hydrogen desorption behavior has been correlated with the surface structure which appears to depend on the carbon to benzene ratio. Thermal stability and hydrogen desorption properties were investigated by DSC. Experimental results on nanocomposites with the same Mg to C weight ratio (70:30) show improved performances for a proper choice of carbon to benzene ratio weight (1/3), even after manipulation of the milled material in air.
Hypervalent Molecular Cluster: C28H4
Authors: Veljković M. , Nešković O. , Djerić A. , Veličković S. , Šipka V.
Published: March 2009

A growing number of recent publications on clusters reflect a tremendous interest in
these particles. These studies reveal new fundamental physical and chemical aspects of matter. Clusters are called the fifth state of matter: liquid, solid, cluster, gas and plasma. In this work, a carbon cluster was generated by a spark cluster source and detected by single focusing mass spectrometer in situ. We examined the effects of cluster source parameters on the generation of carbon cluster and report our initial results. This method should be useful for studying the mechanism of fullerene formation. In the case when carbon clusters generated in plasma arc are
carried by the Ar or H2 gas flow downstream through a vacuum chamber to the ion source of mass spectrometer, we obtained a small binary carbon cluster C28H4 (hydrogenated fullerene). The empty fullerene is tetravalent and strongly binds four hydrogen atoms, which significantly weakens two different sets of bonds and leads to an open-shell electronic structure. Conclusion is that endohedral C28H4 are hypervalent. We have demonstrated how in situ mass spectrometry has led to the rapid development of an important branch of synthetic fullerene chemistry that has yielded many new small fullerenes and related derivatives with novel structures and properties. The impact of mass spectrometry on the synthesis of fullerene derivatives is the subject of this paper. Significantly, a large fraction of products could be condensed on a specially designed collection plate, which allows further spectroscopic characterization of new derivatives.
The Influence of Surface Modification on Related Functional Properties of Wool and Hemp
Authors: Jovančić P. , Jocić D. , Radetić M. , Topalović T. , Petrović Z.Lj.
Published: March 2009

The new concept of the combined treatment consisting of specific fibre surface tailoring and activation prior to biopolymer or enzyme post-application is introduced. Low-temperature plasma treatment is considered as very useful for superficial treatment of wool and hemp. Some interesting combinations of low-temperature plasma and enzymatic treatments are presented in this paper. These treatments result in an increase in wettability, dimensional stability, polymer adhesion and dyeability of both, wool and hemp fabrics.
Reduction of NiO-WO3 Oxide Mixtures Synthesized by Gel-Combustion Technique: A Route to Ni-W Alloys
Authors: Mentus S. , Majstorović D.M. , Tomić B.S. , Dimitrijević R.
Published: March 2009

The mixtures NiO-WO3 were synthesized by the combustion of gels obtained by drying common solutions of nickel nitrate, polytungstic acid and citric acid. The X-ray diffractograms of oxide mixtures confirmed mutual interaction of oxides during synthesis leading to a new phase, NiWO4. The reduction of oxide mixtures in hydrogen atmosphere was investigated thermogravimetrically. The temperature of reduction of the oxide mixture lies between the temperatures of reduction of pure oxides and monotonously increases with the increase in WO3 mole fraction; however, the reduction itself is a multi-step process, preferably in the composition
region rich in NiO. The X-ray diffractometry of metallic residues evidenced Ni-W alloys and tungsten excess to be the reduction products.
Characterization and Catalytic Activity of Poly(4-Vinylpyridine-Co-Divinylbenzene)-Co2+ Complex
Authors: Lončarević D. , Čupić Ž.
Published: March 2009

Poly(4-vinylpyridine-co-divinylbenzene)-Co2+ was characterized using infrared spectroscopy (IR), thermogravimetric analysis (TG-DTA), N2-physisorption and polarography. Thermal analysis suggests sufficient thermal stability of the polymer support, under reaction conditions. From polarography measurements, the Co2+ content on polymer-supported catalysts is estimated and it was proved that no significant leaching occurred during the activity tests. At the molecular level, FTIR of P4VP-DVB-Co2+ reveals that the pyridine nitrogen lone pair coordinates to the metal center in the polymeric complex. The obtained P4VP-DVB-Co2+ catalysts performed interesting catalytic activity in reaction of the cyclohexane oxidation with air, indicating that increasing Co2+ content lowers the initiation temperature and raises the decomposition of cyclohexylhydroperoxide.
A Kink-Soliton Model of Charge Transport through Microtubular Cytoskeleton
Authors: Keković G. , Raković D. , Satarić M.V. , Koruga Dj.
Published: March 2009

Contemporary trends in science and technology are characterized by integration of biological and technical systems, like in nanotechnology, nanobiology, and quantum medicine. In our case, we were motivated by a necessity to understand charge transport through microtubular cytoskeleton as a constitutive part of acupuncture system. The high frequency component of acupuncture currents, widely exploited in microwave resonance stimulation of acupuncture system in the past decade, implies that explanation of the cytoplasmatic conductivity should be sought in the framework of Frohlich theory. Accordingly, in this paper we critically analyze the problem of the microwave coherent longitudinal electrical oscillations as a theoretical basis for understanding soliton phenomena in microtubules, showing that charged kink-soliton nonlinear microtubular excitations might be a good candidate for charge transport in microtubules.
Effect of Strong Neutron Absorption on Texture and Diffraction Data Analysis
Authors: Volz Heather M. , Vogel Sven C. , Roberts J.A. , Lawson A.C. , Williams D.J. , Daemen L.L.
Published: March 2009

The impact of strong neutron absorption on data analysis and the comparison of two
different absorption corrections for neutron diffraction data implemented in the GSAS Rietveld code are the foci of this work. We investigated the effect of absorption on the texture and the thermal motion parameter for rolled elemental foils. The orientation distribution functions (ODF) of rolled foils of dysprosium and erbium metals were determined from neutron time-of-flight data patterns collected on HIPPO at LANSCE. Both Dy and Er are strong absorbers for thermal neutrons with absorption cross-sections of 994 barns for Dy and 159 barns for Er at l = 1.8 Å. Various stacks of foils of each material, along with combinations of absorbing and less-absorbing foils, were measured. The patterns were analyzed using the GSAS options for Debye-Scherrer and linear absorption models, as well as without an absorption correction. Discrepancies between refined and expected “true” values of crystallographic parameters if absorption is not taken into consideration are discussed.
Nucleation and Texture Development during Dynamic Recrystallization of Copper
Authors: McDonald D.T. , Humphreys John F. , Bate Pete S.
Published: March 2009

Dynamic recrystallization and texture development in polycrystalline copper have been investigated. Specimens were deformed in channel-die plane strain compression to true strains from 0.1 to 0.7 within the temperature range 200°C to 600°C, and the resulting microstructures were investigated with the use of high resolution electron backscatter diffraction (EBSD). Dynamic recrystallization in copper was initiated by the bulging of pre-existing high angle grain boundaries (HAGB), and occurred primarily by strain induced boundary migration (SIBM). Increasing misorientations from parent to dynamically recrystallizing grains indicated the occurrence of lattice rotations within the bulges, leading, in some cases to the formation of a HAGB behind the bulge. Discrimination between recrystallized and deformed components in material which had partially undergone dynamic recrystallization was carried out, followed by texture analysis. This revealed most of the recrystallized material to have orientations close to that of the deformed material, however, some remote orientations were observed which could not be related to the deformation texture by twin or 40° <111> relationships.
Effect of Stacking Fault Energy on Evolution of Recrystallization Textures in Drawn Wires and Rolled Sheets
Authors: Lee Dong Nyung
Published: March 2009

The drawing textures of aluminum, copper, gold, silver, and Cu-7.3% Al bronze wires are approximated by major <111>+minor <100>, except silver wire, which can have the <100> texture at extremely high reductions. The <111> component in the drawing textures of aluminum, copper, gold, and silver transform to the <100> component after recrystallization. On the other hand, the <111> deformation texture of the Cu-7.3% Al bronze wire, which has very low stackingfault- energy, remains unchanged after recrystallization. The Brass component {110}<112> in rolling textures of high stacking-fault-energy metals such as aluminum and copper alloys changes to the Goss orientation {110}<001> after recrystallization. However, the Brass orientation in rolling textures of low stacking-fault-energy fcc metals such as brass appears to change to the {236}<385> orientation after recrystallization. These results seem to be related to the stability of dislocations during annealing.
Cube Texture Development in Pure Ni during Annealing in a High Strength Magnetic Field
Authors: Li Xin Lu , Liu Wei , Godfrey Andrew , Liu Qing
Published: March 2009

A 10 Tesla magnetic field was applied during annealing of cold-rolled high purity Ni at
300°C for 2 hours, with samples aligned at various different angles to the magnetic field direction. The effect of the magnetic field annealing on the cube texture evolution and the microstructural development was investigated by use of electron backscatter pattern (EBSP) analysis in the scanning electron microscope. The results show that both the cube texture evolution and the grain size are affected by the application during annealing of a high strength magnetic field, and that the effect varies as a function of the angle between the sample normal and the magnetic field direction. The cube texture volume fraction resulting from 2 hours annealing increases with increasing angle between the field direction and the sample normal direction, though in nearly all cases lower cube volume fractions were obtained compared to annealing without a magnetic field. The average size for all grains and for just cube-oriented grains both decrease with decreasing cube texture fraction, suggesting that the presence of a magnetic field either leads to enhanced recrystallization nucleation, or to a retardation of grain growth after recrystallization.
Epitaxial Growth of Textured YBa2Cu3O7-δ Films on Silver
Authors: Liu Dan Min , Liu Wei Peng , Suo Hong Li , Zhou Mei Ling
Published: March 2009

YBa2Cu3O7-δ (YBCO) films were deposited on (100), (110) and (111) oriented silver
single crystals and {100}<100>, {110}<211> , {110}<100>+{110}<011>， {110}<011> and {012}<100> textured Ag substrates using pulsed laser deposition. The relationship between the epitaxial growth YBCO film and silver substrate has been determined. It is shown that among polycrystalline Ag substrates, {110}<011> textured tape is suitable for the deposition of YBCO thin
films having strong texture.
Texture Development in Nd-Fe-V Alloys by Hot Deformation in View of Permanent Magnet Properties
Authors: Popa I. , Rivoirard Sophie , Chateigner Daniel , Hansen T. , Fruchart Daniel
Published: March 2009

In this study, a hot forging process is applied to Nd-Fe-V as cast alloys in order to develop both the microstructure and the crystallographic texture appropriate for permanent magnet properties. A neutron diffraction texture analysis is used to account for the extrinsic magnetic anisotropy: the stabilisation of the Nd(Fe,V)12 hard magnetic phase has been achieved during forging but its extrinsic anisotropy level remains low. Attempts to understand this phenomenon are made through a discussion on the Nd-Fe-V alloy rheological and mechanical behaviour and a comparison with Nd-Fe-B permanent magnets.