bluuebunny/crossref_metadata_2025 huggingface dataset:
Ni3Fe Mechanically Alloyed: “Shock Mode” versus “Friction Mode”
Authors: Prică Virgiliu Călin , Marinca Traian Florin , Popa Florin , Chicinaş Ionel
Published: January 2011

Ni3Fe powder has been obtained by high energy ball milling from elemental powders. We used two extreme conditions for milling: “friction mode” – friction between powder and ball/vial– and “shock mode” – direct impact of ball to powders. The influence of milling mode - friction and shock – was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was observed that the Ni3Fe grain size obtained by “friction mode” after 30 hours of milling was around 10 nm. For “shock mode” milling the average grain sizes was around 17 nm after 20 hours. The grain size was calculated using Williamson-Hall formula for both, “shock mode” and “friction mode” of milled powders and Scherrer formula for annealed powders. The powders were subjected to an annealing (30 min. at 350 °C) in order to eliminate the internal stress accumulated to the milling process and to finish the Ni3Fe phase formation.
Research about Obtaining Porous Sintered Multilayer Materials from Stainless Steel Powders
Authors: Vida-Simiti Ioan , Jumate Nicolaie , Cotetiu Artur , Bolog Trandafir
Published: January 2011

Porous samples under the form of disc tablets, 23 mm in diameter and approximately 2 mm thick, were made by freely spreading and then sintering stainless steel powder (316 L). The powder fraction used and the sintering time are the parameters that were varied in order to study their influence on the main structural characteristics. Different powder size ranges were used. The multilayer structure was obtained by freely spreading different particles size ranges -40µm and 100 -125µm in alternative layers. The narrow range (-40µm) of particles was used to obtain a thin layer (0,5mm) intended for small pores size and to maintain the permeability of samples in acceptable limits. The sintered structure was investigated by electron microscopy and mercury porosimetry.
Stainless Steels Sintered Form the Mixture of Prealloyed Stainless Steel and Alloying Element Powders
Authors: Brytan Zbigniew , Grande Marco Actis , Rosso Mario , Bidulský Róbert , Dobrzański L.A.
Published: January 2011

The aim of the presented paper is to describe the sintered duplex stainless steels manufactured in sinter-hardening process and their structural and mechanical properties. Duplex stainless steels were obtained through powder metallurgy starting from austenitic 316L or ferritic 410L prealloyed base powders by controlled addition of alloying elements powder. Prepared mixes were compacted at 700MPa and sintered in a vacuum furnace with argon backfilling at temperature of 1240°C for 1h. After sintering different cooling cycles were applied: rapid cooling (6°C/s) using nitrogen under pressure and slow cooling (0.1°C/s) with furnace in argon atmosphere. Produced sintered duplex stainless steels were studied by scanning and optical microscopy and EDS chemical analysis of microstructure components as well as X-ray analysis. Mechanical properties were studied through tensile and three-point bending tests and Charpy impact test. It was demonstrated that austenitic-ferritic microstructures with regular arrangement of both phases and absence of precipitates can be obtained with properly designed powder mix composition as well as sintering cycle with rapid cooling rate. Produced sintered duplex steels show good mechanical properties which depend on austenite/ferrite ratio in the microstructure and elements partitioning (Cr/Ni) between phases. The optimal mechanical properties were obtained for compositions based on ferritic 410L powder where the balanced distribution of α and γ is present and the tensile strength can reach value about 500MPa with 16% of elongation and impact energy about 120J. The precipitations of hard intermetallic σ-FeCr phase take place when sintering with slow cooling cycle what cause substantial decrease of plastic properties, including reduce of elongation to 7% and in particular decrease of impact energy to 68 J.
Mechano-Synthesis of Nanocrystalline FeTi-Al-Ni Intermetallic Alloy for Hydrogen Storage
Authors: Orban Radu Liviu , Lucaci Mariana , Jumate Nicolaie , Salomie Dana
Published: January 2011

FeTi has one of the highest hydrogen volume storage capacity and its hydride - very favourable absorption/desorption conditions and a high reversibility. However, for applications its low hydrogen mass storage capacity (HMSC) has to be improved. The authors of this paper supposed this would be possible by Al and Ni additions and by a nanocrystalline state. However, FeTi synthesis and alloying with Al and Ni is difficult in a Fe-Ti-Al-Ni system due to the undesired secondary compounds formation. The presented researches proved the possibility of this impediment overcoming and of NiTi-Al-Ni alloy obtaining in a nanocrystalline state, from a mixture of elemental powders of components, by mechano-synthesis carried out in a planetary ball mill, for 24 h, in Ar atmosphere. The obtained alloy proved to have a HMSC of ~3.5 % at 50 0C and 1.5 atm, higher than of FeTi, its dehydrogenation occurring at the same temperature and 1.0 atm.
The Influence of Processing Parameters on the Magnetic Properties of the Nanocrystalline Soft Magnetic Composites Based on Ni3Fe
Authors: Neamţu Bogdan Viorel , Isnard Olivier , Chicinaş Ionel , Popa Florin , Geoffroy Oliver , Pop Viorel
Published: January 2011

The nanocrystalline Ni3Fe powders were obtained via wet mechanical alloying route in argon atmosphere. As process control agent (PCA) the benzene (C6H6) was used. In order to release the internal stresses an annealing at 350 °C for 4 hours was performed. Alternatively, the nanocrystalline Ni3Fe powder was subjected to a process of incipient recrystallization at 600 °C for 30 minutes in vacuum. The recrystallised powders have a crystallite size of 30 nm. The magnetic properties (the frequencies dependence of permeability and magnetic losses) were investigated in AC field of 0.05, 0.1 and 0.2 T. It was found that the polymerization process has a strong influence over the magnetic properties of compacts. If the polymerization was performed by heating the powders into a mould, generally we observed a positive influence over the permeability but a negative influence over the magnetic losses.
Powder Metallurgy Processing of Al/TiAl3+Al2O3
Authors: Csáki Ioana , Moldovan Petru , Popescu Gabriela
Published: January 2011

This paper aims to present a way of obtaining aluminum based composite material obtained by powder metallurgy technique. We start mixing and milling the powders, compressing and sintering the samples. We established a sintering cycle for this type of composite material and studied obtained samples by SEM microscopy. The reaction between the matrix and the precursor of the reinforcing materials was studied with the aid of HSC 4.0 program, available at Engineering and Management of Metallic Materials department.
Influence of the Mechanical Alloying Parameters on the Elaboration of Sic/Al Nanocomposite Powders
Authors: Nicolicescu Claudiu , Ciobanu Mariana , Leonat Lucia
Published: January 2011

The paper presents the experimental work regarding the elaboration of some nanocomposite powders with higher SiC content. For the research, three types of mixtures were prepared: 90SiC-10Al, 70SiC-30Al and 60SiC-40Al using mechanical alloying (MA) technique. The MA was carried out in a vario planetary ball mill Pulverisette 4 for 5 hours using different conditions: - the shock mode (the main disk speed 400 rpm and the planets speed -800 rpm); - the friction mode (the main disk speed 400 rpm and the planets speed 800 rpm). The resulting mixtures was investigated by scanning electron microscopie (SEM), X-ray diffraction pattern (RDX), energy dispersive X-ray analysis (EDAX) and particle size distribution. After 5 hours of MA it is observed that the mixture obtained in the friction mode conditions have a homogenous structure and the particle size distribution is better than the particle size distribution of the mixture obtained in the shock mode conditions.
Gigacycle Fatigue Response of PM versus Ingot Metallurgy Tool Steels
Authors: Danninger Herbert , Sohar Christian , Gierl Mayer Christian , Betzwar-Kotas Agnieszka , Weiss Brigitte
Published: January 2011

In this work, the gigacycle fatigue response of several tool steel grades has been studied using an ultrasonic resonance testing device. It showed that both with ingot metallurgy (IM) and powder metallurgy (PM) tool steels, a true fatigue limit does not exist up to 10E10 cycles. PM steels resulted in significantly higher endurance strength levels than IM grades. However, there was virtually no effect of the composition and hardness of the materials, both for PM and IM grades cold work tool steels and high speed steels exhibiting virtually the same S-N curves. In the IM tool steel grades, crack initiation started at large primary carbides or carbide clusters, while in the PM grades, nonmetallic inclusions were the critical sites. In any case it is very important to avoid introducing residual stresses into the specimen surfaces during preparation, which would markedly shift the endurance strength levels.
Preliminary Studies Regarding the Behaviour of New Titanium Implants
Authors: Roman Călin Rareş , Sorcoi Lidia Adriana
Published: January 2011

This paper presents a study concerning a new titanium-based product reached by the specific techniques of powder metallurgy. The product was tested in vitro to corrosion in artificial saliva and in vivo by biological inocuity on sheep and rats for biocompatibility. The chemical composition of artificial saliva solutions used for general corrosion tests were: Fusayama solution; Carter solution; Ericsson solution; Hank solution; Ringer solution. The exposure length was 48, 720, 1440 and 2784 hours. On the sheep, six titanium implants of purity 99.89%, sintered with microporosities and nanoporosities at the surface were administered. Function of implant location, three cm incisions in the skin was made in the following regions: retroscapular for subcutaneous implants, in the tibial diaphysis for the subperiostal implant and in the Latimus Dorsi region for the intramuscular implant. Three different lots of Wistar breed rats were used; the sintered 3.5/1.5 cm titanium implants were placed subcutaneously and intermuscles. Parameters of descriptive statistics were used to assess inflammatory reaction.
Modification of the Structural Characteristics of the Tungsten Powder through Short Mechanical Milling Processes
Authors: Salomie Dana , Jumate Nicolae
Published: January 2011

The objective of this study is to improve the sintering of W powder through increasing the density of the crystalline structure imperfections. The powder of W was processed by short processes of mechanical milling in a high energy planetary mill. The paper presents the influence of mechanical milling process duration upon the modifications of the structural characteristics of W powder. The fine structure has been studied by using X-ray diffraction.
The Effect of Time of Powder Removal on Powder Particle Size and Shape Copper Powder Produced by Electrolysis Method
Authors: Kurt Adem , Boz Mustafa
Published: January 2011

In this study, electrolyze unit, which is used for the production of metal powders, was designed and produced. The production of powder was carried out by using different parameter times of powder removal (5, 10, 20, 30 and 40 min.). The effect of time of powder removal on powder particle size and shape was examined. Laser particle measurement machine and SEM were also used to measure particle size and particle shape respectively. Experimental results indicated that an increase in time of powder removal caused an increase in powder particle size and its shape changed from acicular dentritic to globular dentritic.
Influences of the Elaboration Conditions and Addition of Ni and Co on the Some Properties of the W-Cu Electrical Contacts
Authors: Ştefan Iulian , Nicolicescu Claudiu , Gavrila Marin
Published: January 2011

This paper presents a study about the influence of some alloying elements like Ni and Co on the elaboration of W-Cu electrical contacts. For the experimental work four types of mixture were prepared using mechanical alloying (MA) technique for six hours. All the samples had the same Ni and Co content (2%) varying the W content as following: 88W-10Cu-Ni, 78W-20Cu-Ni, 68W-30Cu-Ni, 88W-10Cu-Co, 78W-20Cu-Co and 68W-30Cu-Co. The mixtures were pressed in a cylindrical die with 10 mm diameter at two pressures: 400MPa and 600 MPa. The sintering process was carried out in an electrical furnace at the 1180 OC and maintained at this temperature for three hours. For all the samples the electrical properties: resistivity, conductivity, resistance were measured and were made correlation between electrical contacts with Ni and the other with Co. It is observed that, the compaction pressure influence the electrical properties and better properties are obtained for the samples compacted at 600 MPa.
Comparison between Microwave and Microwave Plasma Sintering of Nickel Powders
Authors: Breen Aidan P. , Twomey Barry , Byrne Greg , Dowling Denis P.
Published: January 2011

The objective of this study is to investigate the use of microwave plasma treatments as a processing technology for the sintering of metal powders. The volumetric heating process achieved with microwaves is considerably more efficient compared with resistance heating. The sintering study was carried out on 20 mm diameter by 2 mm thick compacted discs of nickel powder, with mean particle size of 1 µm. The discs were fired in a 5 cm diameter microwave plasma ball, under a hydrogen atmosphere at a pressure of 2 kPa. There was an increase in fired pellet transverse rupture strength (TRS) with plasma treatment duration. The mechanical properties of the sintered nickel discs were compared based on TRS, Rockwell hardness tests and density measurements. The morphology of the sintered discs was compared using microscopy and SEM. Comparison disc sintering studies were carried out using both a non plasma microwave and tube furnace firing. Using the microwave plasma sintering process full sintered disc strength of ≈1000 N (based on 3-point bend tests) was achieved after a 10 minute treatment time. In contrast the sintering time in the tube furnace treatment involved total processing time of up to 6 hours. The non plasma microwave system involved intermediate treatment periods of 2 hours. The degree of sintering between the individual nickel powder particles can be precisely controlled by the duration of the treatment time in the plasma.
Effect of Foaming Agent on the Structure and Morphology of Al and Alumix 231 Foams Produced by Powder Metallurgy
Authors: Turker Mehmet , Ozcatalbas Yusuf , Cinici Hanifi , Gokmen Ugur , Uzun Arif
Published: January 2011

In this study various amounts of foaming agent (TiH2 % 0,5-1-1,5-2 ) were added to Al and Alumix 231 powders (Al-Cu %2,5-Mg %0,5–Si %14) and mixed for 30 minutes in a three dimensional turbula. Mixed powders were compacted and then foamed freely at 690°C. Effect of foaming agent on the structure, shape and distribution of pores together with linear expansion, density of the foam and wall thickness of the cell of both materials were investigated. In all conditions foam produced from Alumix 231 powders had more homogenous distribution of the pore compare to the sample produced from pure Al powders.
High Resistance Porous Pieces Obtained by PM, Reinforced with Metallic Yarns
Authors: Didu Marin , Gruionu Lucian Gheorghe , Radu Stefan , Ghermec Christian
Published: January 2011

The paper presents the results of the experiment in the fields of new technologies of obtaining PM reinforced with metallic yarns pieces. This type of high resistance porous pieces are made from a base part from recovered low alloyed steel or iron powder reinforced in the border zone with high alloyed steel yarns. For the reinforcing have been used solid yarns Φ 0,3 mm and mixed yarns Φ 0,45 mm. There have been obtained parallelipipedic samples reinforced with four yarns placed as in fig.1.1. The samples have been pressed at 300-600 MPa pressure. The pressing has been made orthogonal onto the placement direction of the yarns. The compacting has been made in an unidirectional compression mould with section of 7x51mm. The sintering was made at 1200 degree Celsius in an argon medium. The sintered samples have densities of 5,72g/cm3 (pressed at 300MPa) and 6,72 g/cm3 (pressed at 600MPa). There have been made mechanical bending tests. There were obtained bending strengths σi=490…800 MPa. From the things previously presented it can be observed that this type of reinforced with yarns pieces have high bending strength, though they have high porosity (low density).
Production of Ceramics Reinforced Al Foams by Powder Metallurgy Techniques
Authors: Turker Mehmet
Published: January 2011

Powders metallurgy route was used to produce foams from pure Al powders and pre-alloyed Al alloy powders (Alumix 231) with or without reinforcing elements addition. Both classical Al foam and spherical Al foam were produced with various production parameters and the results obtained have been discussed. SiC particles were used as reinforcing elements and TiH2 powders were used as foaming agent. Prior to compaction process, Al powders, reinforcing element and foaming agent were mixed in a three dimensional turbula for 30 min. Mixed powders were compacted, sintered and deformed and then foamed at 690 oC for spherical foam and 710 oC for classical foam. Effect of volume fraction of reinforcing elements, foaming temperatures and foaming agent amounts on the foaming behavior, pore structure, pore distribution, linear expansion rate, density and wall thickness of the cell were investigated. Experimental studies have shown that 1% foaming agent and 4 % SiC addition was found to be the most suitable for foaming. In general foam produced from Alumix 231 powders exhibited more homogenous pore structure compared to the ones produced from pure Al powders.
Effect of Manganese Addition and Sintering Conditions on Mechanical Properties of Low Carbon 3Cr Prealloyed Steels
Authors: Šalak Andrej , Selecká Marcela
Published: January 2011

Mechanical properties, microstructure and fracture of Fe-3Cr-0.5Mo-xMn steels sintered laboratory at 1250°C and industrially at 1180°C, and of Fe-3Cr-0.3Mo-0.3V-xMn steels laboratory sintered at 1200°C are presented; all steels with 0.24% C. The highest tensile strength of 806 and 856 MPa attained the steels with 2% Mn based on Fe-3Cr-0.5Mo powder and of 929 MPa the Fe-3Cr-0.3Mo-0.3V-1.5Mn-0.24C steels. Linear increase of hardness and relatively linear decrease of impact energy in dependence on Mn addition was recorded. Tested steels exhibited lower heterogeneity of the microstructures. The fracture of steel containing vanadium with 2% Mn showed more metallic inclusions adversely affecting the strength properties.
The Influence of Cu-Coating versus Admixing on Mechanical Properties and Dimensional Change of Sintered Fe-Cu Parts
Authors: Strobl Susane , Wagesreither J. , Gierl Mayer Christian , Dlapka M. , Kupková Miriam , Kupka Martin , Černý Martin
Published: January 2011

The differences in mechanical properties of pressed and sintered specimens made from mixtures of iron and copper powders or from copper-coated iron powders, produced by a cementation process, were studied. For this purpose different copper contents were used (3, 8 or 12wt%) and the oxygen content of the coated powders was measured. After sintering at 1120°C for 60 minutes in hydrogen flow, microgradient structures were observed. The samples were investigated by light optical microscopy and tested under bending and tensile loads. Young´s Moduli were calculated from resonance frequencies. The copper-coating of the iron powder results in an improvement of all properties, owing to a more homogeneous copper distribution and the absence of large secondary pores, compared to specimens made from mixtures of iron and copper powders. In the case of Fe-12Cu (coated), all determined properties tend to result in a maximum: highest sintered density (7,33 g/cm³), tensile strength (489 MPa), transverse rupture strength (1098 MPa) and apparent hardness (162 HV10). The Young´s Modulus (150 GPa) of coated Fe-12Cu is nearly the same as that of sintered iron (154 GPa).
Observation about Obtaining Maximum Compactness Products via Compact Packing
Authors: Spârchez Zeno
Published: January 2011

The optimum concentration of the spherical powder constituents of a mixture aimed at compact packing in free state or in pressed state depends on the compactness of each component in the same state as the mixture. Due to the packing manner of the components in the mixture, the compactness of each constituent is lower when they are found in the mixture than in the case when they are unmixed. Taking as initial condition the ideal concentration of the components established with Furnace relation, the paper presents a graphic-experimental method than enables the determination of the optimum concentration of the components of a mixture of maximum compactness by using nomogrames. The method performing a minimum number of experiments and by using the nomogrames.
Physical Properties of Bonded Nanocomposite Type Hard-Soft Magnets
Authors: Dorolti Eugen , Todoran Alex , Gutoiu Maria Simona , Takacs Albert Flavius , Chicinaş Ionel , Popa Florin , Pop Viorel
Published: January 2011

The exchange spring magnetic powders of SmCo5/α-Fe were obtained by mechanical milling and annealing. SmCo5+20 wt% α-Fe powder milled for 8 h and annealed at about 550 °C was considered to be more appropriate for our purpose. The isotropic nanocomposite permanent magnets were obtained by bonding the magnet powder in a binder matrix. Several ratios from 0.5 to 1.5 wt % between binder and magnetic powder were used. The composite material was compacted in dies at pressure from 600 to 800 MPa. The heat treatments for polymerisation were performed at 180 °C for 1h. The density and the microstructure of the magnets are discussed in connection with the properties of the starting powder and processing conditions. Magnetic characteristics of Br, Hc and (BH)max were obtained from hysteresis curves in magnetic fields up to 10 T.
Experiment Study on the Hot-Shock Consolidation of Tungsten Powder
Authors: Zhou Qiang , Chen Peng Wan , Gao Xiang , Shen Wei Ping
Published: January 2011

Experiments have been conducted to consolidate tungsten powder using hot-shock consolidation technique combining with underwater shock wave. An exothermic mixture (TiO2-C-Al-Fe2O3) was ignited by an electric wire coil to release a large mount of heat via a self-propagating high-temperature synthesis reaction which was used to pre-heat the sample powder. As getting the needed isothermal temperature, the powder was subsequently consolidated by shock wave generated by explosion of nitro methane, with a detonation velocity of 6.3 km/s and a detonation pressure of 11.9 GPa. The density and Vickers micro-hardness of the consolidated sample were determined and its microstructure was analyzed by scanning electron microscope (SEM). High-density tungsten samples were obtained by optimizing the experimental conditions. In this paper, the relative density and hardness of the recovered sample are 96.5% and 670 HV, respectively.
Explosive Welding of ZrTiCuNiBe Bulk Metallic Glass to Crystalline Cu Plate
Authors: Chiba Akira , Kawamura Yoshihito , Nishida Minoru , Yamamuro Takateru
Published: January 2011

Metallic glass or amorphous alloys have been gaining popularity due to their low density, high strength, high fracture toughness, good corrosion and good wear resistance. Especially, bulk metallic glasses (BMGs), which are made in bulk form with a thickness of ~10mm at slow cooling rates of the order of 1~100K/s, have been noted as an industrial application. The welding to other materials becomes very important. Explosive welding of most popular Zr41.2Ti13.8Cu10Ni12.5Be22.5 bulk metallic glass to crystalline pure Cu plate is investigated in this paper and the BMG was found to retain the amorphous structure. The sound bonding with other materials is expected to push forward the application of BMGs for industrial usage.
Energy Dissipation in Explosive Welding of Dissimilar Metals
Authors: Saravanan Somasundaram , Raghukandan Krishnamorthy
Published: January 2011

Explosive welding of two dissimilar metallic sheets is accomplished by the exhaustive deformation owing to high pressure and high temperature created at the collision place. This study addresses the analytical estimation of the dissipation of potential energy of the explosive initially to mechanical energy and then to thermal energy in dissimilar Copper – Low carbon steel combination. The emanating pressure in the region of detonation front is transmitted to flyer surface as compressive stress wave and a reflective tensile wave is generated at the bottom surface of the flyer. A dilational wave and shear wave are generated. As the flyer plate moving with the transmitted wave collides with the parent, the available kinetic energy is converted into thermal energy to produce adequate heat to induce plastic deformation thus resulting into a strong metallurgical bond.
Shock Synthesis and Characterization of a High-Pressure Phase of TiO2
Authors: Chen Peng Wan , Gao Xiang , Liu Jian Jun , Yin Hao , Huang Feng Lei
Published: January 2011

Different TiO2 precursors were impacted by detonation-driven high velocity flyers to obtain high-pressure phases of titania under instantaneous high temperature and pressure. The factors affecting high-pressure phase synthesis such as loading conditions and titanium dioxide precursors were also studied. The structure and phase composition of the shocked samples are determined by X-ray diffraction (XRD). The microstructure of TiO2 after shock treatment was observed by transmission electron microscopy (TEM).
A Comparison between the Corrosion Resistances of High Velocity Oxy Fuel (HVOF) Sprayed Coatings and Hard Chromium Coatings
Authors: Saghi Beyragh Mohammad Reza , Khameneh Asl Shahin , Vasfpour Rahim , Tazesh Farshid , Khallagi Parisa
Published: January 2011

HVOF-sprayed coatings (WC–17%Co) and hard chromium coatings corrosion resistances have been compared through electrochemical polarization test in 3.5% NaCl solution. WC–17%Co alloy coatings were deposited on mild steel substrates by High Velocity Oxy-Fuel (HVOF) spray process. The layers of standard and crack free hard chromium coatings were prepared by using Direct Current (DC) and Pulse Current (PC) electroplating process on the mild steel substrates. Hard chromium coatings was characterized as a reference material, to verify whether HVOF-sprayed coatings are suitable as a hard chromium coatings replacement. The microstructure of the coatings was examined by OM, SEM and XRD. Standard hard chromium coatings passivate in NaCl environment, but crack free hard chromium coatings were prepared by using Pulse Current (PC) electroplating do not passivate. The lowest corrosion current densities (Icorr) were recorded for crack free hard chromium coatings. Comparative electrochemical test results showed that, the Standard hard chromium coating has the highest Icorr and were significantly damaged after the electrochemical tests. It is seem to be that WC–17%Co alloy coatings can be substituted for standard hard chromium coatings but crack free chromium coatings bring new challenge for HVOF-sprayed coatings!
Development of Magnesium Based Alloys for High Temperature Applications
Authors: Pillai Uma Thanu Subramonia , Srinivasan Amirthalingam , Raghukandan Krishnamorthy , Pai Ballembettu Chandrasekhar
Published: January 2011

Individual and combined additions of elements like Si, Sb, Sr are carried out to AZ91 alloy and its microstructure, mechanical properties especially creep properties and corrosion behavior are investigated. In general, additions of the above elements improve the mechanical properties. Further, the results show these alloying elements introduce thermally stable intermetallics and thereby improve the creep performance. Among various additions, Sb addition provides highest creep resistance. With the Si and Sr additions, the corrosion resistance of AZ91 alloy is improved. Detailed micro-mechanisms are also studied and they are correlated with the properties studied.
Evaporating Cryogenic Fluids by Direct Contacting Normal Temperature Fluids
Authors: Watanabe Toshiaki , Maehara Hironori , Itoh Shigeru
Published: January 2011

In recent years in Japan, the demand of cryogenic fluids like a LH2, LNG is increasing because of the advance of fuel cell device technology, hydrogen of engine, and stream of consciousness for environmental agreement. On the other hand, as for fisheries as well, the use of a source of energy that environment load is small has been being a pressing need. We paid attention to the effective use of cold heat of the liquid fuel which is a cryogenic fluid. That method is to use a cold heat which an cryogenic fluid has, without a heat exchanger. The mixture of the extreme low temperature fluid and the normal temperature fluid becomes the cause which causes pressure vessel and piping system crush due to explosive boiling and rapid freezing. Therefore, we carried out the experiments related to promotion of evaporating cryogenic fluids, in the contact directly of the room temperature fluids and cryogenic fluids.
Behavior of Bubble in Small Water Tank Used for Food Processing Using Underwater Shock Wave
Authors: Hamashima Hideki , Shibuta Manabu , Itoh Shigeru
Published: January 2011

The food processing technology using a shock wave can prevent deterioration of the food by heat because it can process food in a short time. Generally, since the shock wave used for food processing is generated by underwater explosion, the load of a shock wave to the food becomes very complicated. Therefore, in order to process safely, it is important to clarify the behaviors of the shock wave and the bubble pulse generated by underwater explosion. In this research, in order to investigate the behavior of the shock wave in the water tank used for food processing, the optical observation experiment and the numerical simulation were performed. In the experiment, the shock wave generated by underwater explosion was observed with the high-speed video camera. The numerical simulation about the behavior of bubble pulse was performed using analysis software LS-DYNA. Comparing and examining were performed about the experimental result and the numerical simulation result. The result of the numerical simulation about the behavior of the shock wave generated by underwater explosion and the shock wave generated by the bubble pulse and the bubble pulse was well in agreement with the experimental result.
Impact Behavior of Biaxially Compressed Wood
Authors: Yamashita Minoru , Sawada Noriyuki , Hattori Toshio
Published: January 2011

The wood bar with square cross-section was biaxially compressed with respect to the cross-sectional plane and the impact 4-point bending test was performed using the compressed wood. The wood material used was sap wood of Sugi, which is a kind of Japanese cedar. The biaxial compression apparatus which enabled to prevent the gap generation between the material and the tool was used. The fixation of wood specimen was also processed. The bar length was 100 mm and the edge length in cross-section was 15 ~ 25 mm. In the 4-point bending test, the distance between the supports and the stress points were 80 mm and 40 mm. The stress points were impacted by a light-weight drop-hammer with 3.0 kg mass. The impact velocity was 2 m/s. The surface strain was measured by a strain gage. When the Young’s modulus was estimated by assuming a linear elastic property, it attained about 32 GPa, which was more than 4 times of the uncompressed wood. The stress – strain hysteresis loop was more remarkable under the impact condition. It was found that the compressed wood provided not only a high rigidity, but also a good property in dissipation of vibration energy.
Structural Evolution of the Cu-Ni Solid Solution Formed by Ball Mechanical Alloying Treatment (BMAT)
Authors: Farahbakhsh Iman , Zakeri Alireza , Manikandan Palavesamuthu , Hokamoto Kazuyuki
Published: January 2011

A nanostructured powder with uniform distribution of Ni and Cu powders was produced by means of the Ball Mechanical Alloying Treatment (BMAT). Mutual diffusion of Ni and Cu in the nanostructured layer and the microstructure of the cross section of the remaining powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Electron Probe Microanalyzer (EPMA). X-ray diffraction patterns revealed that increasing the milling time gives rise to decreasing crystallite size and lattice parameter during the MA process. Furthermore, scanning electron microscopy (SEM) was utilized not only for evaluating the morphology and microstructure of the remaining powder particles but also for proving this claim that during MA process, the mutual diffusion of Ni and Cu has occurred. Elemental mappings also show that the alloying process occurred in samples but obtaining the uniform shape, size and microstructure of the powder requires increase in the milling time.
Dynamic Forming of AZ91 Magnesium Alloy Using Explosive Energy
Authors: Ruan Li Qun
Published: January 2011

Magnesium alloys are poor in ductility at room temperature and it is known that the cold working is very difficult. Therefore, the development of forming methods, especially at normal temperature, is highly expected [1]. In this paper, AZ91 magnesium block were accelerated more than 100 m/s and the magnesium alloy was well deformed into the die gap. The cross-sectional microstructure was characterized and the deformation of the magnesium was discussed.
Experimental Study in H2/CO/CH4–Air and H2/CO/C3H8–Air Premixed Flames. Part 2: Cellular Instabilities
Authors: Vu Tran Manh , Park Jeong , Kim Jeong Soo , Kwon Oh Boong , Yun Jin Han , Keel Sang In
Published: January 2011

Experiments in a constant pressure combustion chamber at room temperature and elevated pressures using schlieren system were conducted to investigate the cellular instabilities in hydrogen/carbon monoxide/methane (or propane)–air premixed flames. In the present study, hydrodynamic and diffusional-thermal instabilities were evaluated to elucidate their effects to flame instabilities. Effective Lewis numbers of premixed flames with methane addition decrease for all of the cases. Meanwhile, the effective Lewis numbers with propane addition increase for lean and stoichiometric conditions, but they increase for rich and stoichiometric cases for hydrogen-enriched flames. With propane addition, the propensity for cells formation is significantly diminished whereas the cellular instabilities for hydrogen enriched flames are promoted. With methane addition, the similar behavior of cellularity is obtained, indicating that methane is not a candidate for suppressing cells formation in hydrogen/carbon monoxide/methane–air premixed flames.
A Novel and Divergent Role of Granzyme A and B in Resistance to Helminth Infection
Authors: Hartmann Wiebke , Marsland Benjamin J. , Otto Benjamin , Urny Jens , Fleischer Bernhard , Korten Simone
Published: January 2011

Granzyme (gzm) A and B, proteases of NK cells and T killer cells, mediate cell death, but also cleave extracellular matrices, inactivate intracellular pathogens, and induce cytokines. Moreover, macrophages, Th2 cells, regulatory T cells, mast cells, and B cells can express gzms. We recently reported gzm induction in human filarial infection. In this study, we show that in rodent filarial infection with Litomosoides sigmodontis, worm loads were significantly reduced in gzmA×B and gzmB knockout mice during the whole course of infection, but enhanced only early in gzmA knockout compared with wild-type mice. GzmA/B deficiency was associated with a defense-promoting Th2 cytokine and Ab shift, enhanced early inflammatory gene expression, and a trend of reduced alternatively activated macrophage induction, whereas gzmA deficiency was linked with reduced inflammation and a trend toward increased alternatively activated macrophages. This suggests a novel and divergent role for gzms in helminth infection, with gzmA contributing to resistance and gzmB promoting susceptibility.
The Evolution and Regulation of the Mucosal Immune Complexity in the Basal Chordate Amphioxus
Authors: Huang Shengfeng , Wang Xin , Yan Qingyu , Guo Lei , Yuan Shaochun , Huang Guangrui , Huang Huiqing , Li Jun , Dong Meiling , Chen Shangwu , Xu Anlong
Published: January 2011

Both amphioxus and the sea urchin encode a complex innate immune gene repertoire in their genomes, but the composition and mechanisms of their innate immune systems, as well as the fundamental differences between two systems, remain largely unexplored. In this study, we dissect the mucosal immune complexity of amphioxus into different evolutionary-functional modes and regulatory patterns by integrating information from phylogenetic inferences, genome-wide digital expression profiles, time course expression dynamics, and functional analyses. With these rich data, we reconstruct several major immune subsystems in amphioxus and analyze their regulation during mucosal infection. These include the TNF/IL-1R network, TLR and NLR networks, complement system, apoptosis network, oxidative pathways, and other effector genes (e.g., peptidoglycan recognition proteins, Gram-negative binding proteins, and chitin-binding proteins). We show that beneath the superficial similarity to that of the sea urchin, the amphioxus innate system, despite preserving critical invertebrate components, is more similar to that of the vertebrates in terms of composition, expression regulation, and functional strategies. For example, major effectors in amphioxus gut mucous tissue are the well-developed complement and oxidative-burst systems, and the signaling network in amphioxus seems to emphasize signal transduction/modulation more than initiation. In conclusion, we suggest that the innate immune systems of amphioxus and the sea urchin are strategically different, possibly representing two successful cases among many expanded immune systems that arose at the age of the Cambrian explosion. We further suggest that the vertebrate innate immune system should be derived from one of these expanded systems, most likely from the same one that was shared by amphioxus.
Visualizing the Role of Cbl-b in Control of Islet-Reactive CD4 T Cells and Susceptibility to Type 1 Diabetes
Authors: Hoyne Gerard F. , Flening Eleanor , Yabas Mehmet , Teh Charis , Altin John A. , Randall Katrina , Thien Christine B. F. , Langdon Wallace Y. , Goodnow Christopher C.
Published: January 2011

The E3 ubiquitin ligase Cbl-b regulates T cell activation thresholds and has been associated with protecting against type 1 diabetes, but its in vivo role in the process of self-tolerance has not been examined at the level of potentially autoaggressive CD4+ T cells. In this study, we visualize the consequences of Cbl-b deficiency on self-tolerance to lysozyme Ag expressed in transgenic mice under control of the insulin promoter (insHEL). By tracing the fate of pancreatic islet-reactive CD4+ T cells in prediabetic 3A9-TCR × insHEL double-transgenic mice, we find that Cbl-b deficiency contrasts with AIRE or IL-2 deficiency, because it does not affect thymic negative selection of islet-reactive CD4+ cells or the numbers of islet-specific CD4+ or CD4+Foxp3+ T cells in the periphery, although it decreased differentiation of inducible regulatory T cells from TGF-β–treated 3A9-TCR cells in vitro. When removed from regulatory T cells and placed in culture, Cblb-deficient islet-reactive CD4+ cells reveal a capacity to proliferate to HEL Ag that is repressed in wild-type cells. This latent failure of T cell anergy is, nevertheless, controlled in vivo in prediabetic mice so that islet-reactive CD4+ cells in the spleen and the pancreatic lymph node of Cblb-deficient mice show no evidence of increased activation or proliferation in situ. Cblb deficiency subsequently precipitated diabetes in most TCR:insHEL animals by 15 wk of age. These results reveal a role for peripheral T cell anergy in organ-specific self-tolerance and illuminate the interplay between Cblb-dependent anergy and other mechanisms for preventing organ-specific autoimmunity.
The IL1RN Promoter rs4251961 Correlates with IL-1 Receptor Antagonist Concentrations in Human Infection and Is Differentially Regulated by GATA-1
Authors: Carrol Enitan D. , Payton Antony , Payne Deborah , Miyajima Fabio , Chaponda Mas , Mankhambo Limangeni A. , Banda Daniel L. , Molyneux Elizabeth M. , Cox Helen , Jacobson Greg , Carr Daniel F. , Molyneux Malcolm E. , Stewart James P. , Quinn John P. , Hart C. Anthony , Ollier William E.
Published: January 2011

IL-1R antagonist (IL-1Ra) is required for adequate host defense in invasive pneumococcal disease (IPD). The minor allele of an IL1RN gene (C/T) promoter polymorphism (rs4251961) has been shown to be associated with decreased IL-1Ra production in healthy adults. We genotyped 299 children with IPD, and examined 19 IL1RN haplotype-tagging single-nucleotide polymorphisms. Human embryonic kidney HEK293(T) cells were transfected with the promoter reporter plasmid pGL3p containing either allelic variant C (pGL3pCC) or T (pGL3pTT) with or without cotransfection with an expression construct overexpressing the globin transcription factor GATA-1. Plasma IL-1Ra concentrations were significantly higher in nonsurvivors compared with survivors (p < 0.0005), and the C allele of rs4251961 was associated with a significant increase in plasma IL-1Ra concentrations (p = 0.01) during the acute illness of IPD. These findings were validated in a cohort of 276 treatment-naive HIV-infected adults, with borderline significance (p = 0.058). Functional analyses demonstrated that the activity of the promoter constructs containing the T allele increased ~6-fold as compared with basal activity, and that containing the C allele by ~9-fold (p < 0.001) in the presence of GATA-1. Our findings suggest that the IL-1Ra single-nucleotide polymorphism rs4251961 plays a key role in the pathophysiology of IPD and in other human infections.
Accelerated Dendritic Cell Differentiation from Migrating Ly6Clo Bone Marrow Monocytes in Early Dermal West Nile Virus Infection
Authors: Davison Ariane M. , King Nicholas J. C.
Published: January 2011

No study has investigated the participation of Ly6C+ monocytes in the earliest phase of skin infection with the mosquito-borne West Nile virus. In a novel murine model mimicking natural dermal infection, CCL2-dependent bone marrow (BM)-derived monocyte migration, differentiation into Ly6C+ dendritic cells (DC), and accumulation around dermal deposits of infected fibroblasts by day 1 postinfection were associated with increasing numbers of monocyte-derived TNF/inducible NO synthase-producing DC by day 2 postinfection in draining auricular lymph nodes (ALN). Adoptive transfer demonstrated simultaneous migration of bone marrow-derived Ly6Clo monocytes to virus-infected dermis and ALN, where they first become Ly6Chi DC within 24 h and then Ly6Clo DC by 72 h. DC migration from the infected dermis to the ALN derived exclusively from Ly6Clo BM monocytes. This demonstrates that Ly6Chi and Ly6Clo BM-derived monocytes have different fates in vivo and suggests that BM may be a reservoir of preinflammatory monocytes for rapid deployment as inflammatory DC during virus infection.
Essential Role of E3 Ubiquitin Ligase Activity in Cbl-b–Regulated T Cell Functions
Authors: Paolino Magdalena , Thien Christine B. F. , Gruber Thomas , Hinterleitner Reinhard , Baier Gottfried , Langdon Wallace Y. , Penninger Josef M.
Published: January 2011

E3 ubiquitin ligases have been placed among the essential molecules involved in the regulation of T cell functions and T cell tolerance. However, it has never been experimentally proven in vivo whether these functions indeed depend on the catalytic E3 ligase activity. The Casitas B-cell lymphoma (Cbl) family protein Cbl-b was the first E3 ubiquitin ligase directly implicated in the activation and tolerance of the peripheral T cell. In this study, we report that selective genetic inactivation of Cbl-b E3 ligase activity phenocopies the T cell responses observed when total Cbl-b is ablated, resulting in T cell hyperactivation, spontaneous autoimmunity, and impaired induction of T cell anergy in vivo. Moreover, mice carrying a Cbl-b E3 ligase-defective mutation spontaneously reject tumor cells that express human papilloma virus Ags. These data demonstrate for the first time, to our knowledge, that the catalytic function of an E3 ligase, Cbl-b, is essential for negative regulation of T cells in vivo. Thus, modulation of the E3 ligase activity of Cbl-b might be a novel modality to control T cell immunity in vaccination, cancer biology, or autoimmunity.
Mice Lacking Ly49E Show Normal NK Cell Development and Provide Evidence for Probabilistic Expression of Ly49E in NK Cells and T Cells
Authors: Aust Jonathan G. , Gays Frances , Hussain Farhana , Butcher Geoffrey W. , Kist Ralf , Peters Heiko , Brooks Colin G.
Published: January 2011

Ly49E is an unusual member of the Ly49 family that is expressed on fetal NK cells, epithelial T cells, and NKT cells, but not on resting adult NK cells. Ly49Ebgeo/bgeo mice in which the Ly49E gene was disrupted by inserting a β-geo transgene were healthy, fertile, and had normal numbers of NK and T cells in all organs examined. Their NK cells displayed normal expression of Ly49 and other NK cell receptors, killed tumor and MHC class I-deficient cells efficiently, and produced normal levels of IFN-γ. In heterozygous Ly49E+/bgeo mice, the proportion of epidermal T cells, NKT cells, and IL-2–activated NK cells that expressed Ly49E was about half that found in wild-type mice. Surprisingly, although splenic T cells rarely expressed Ly49E, IL-2–activated splenic T cells from Ly49Ebgeo/bgeo mice were as resistant to growth in G418 as NK cells and expressed similar levels of β-geo transcripts, suggesting that disruption of the Ly49E locus had increased its expression in these cells to the same level as that in NK cells. Importantly, however, the proportion of G418-resistant heterozygous Ly49E+/bgeo cells that expressed Ly49E from the wild-type allele was similar to that observed in control cells. Collectively, these findings demonstrate that Ly49E is not required for the development or homeostasis of NK and T cell populations or for the acquisition of functional competence in NK cells and provide compelling evidence that Ly49E is expressed in a probabilistic manner in adult NK cells and T cells.