bluuebunny/crossref_metadata_2025 huggingface dataset:
Martensitic Transformations of Ni54Mn25Ga21-xAlx Shape Memory Alloys
Authors: Xin Yan , Li Yan , Jiang Cheng Bao , Xu Hui Bin
Published: March 2009

The non-stoichiometric NiMnGa shape memory alloy with high Ni content has been
developed as promising thermo-actuated materials applied at high temperature. A substitution of Al for Ga in the Ni54Mn25Ga21 alloys is performed. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements have been carried out to study the effects of the phase transformations and microstructures of the Ni54Mn25Ga21-xAlx shape memory alloys. The results show
that the martensitic transformation temperatures almost linearly decrease with the increase of Al substitution for Ga, which can be explained considering the effect of the size factor, i.e. the lattice parameter. A structural transition from a non-modulated tetragonal type to a seven-layered 14M one has been found during the increase of Al substitution for Ga.
Martensitic Transformation of Ni2.18Mn0.82Ga Single Crystal Observed by Synchrotron Radiation White X-Ray Diffraction
Authors: Inoue Kazuko , Yamaguchi Yasuo , Ohsumi Kazumasa , Kusaka Katsuhiro , Nakagawa Takeshi
Published: March 2009

A Heusler-type Ni2.18Mn0.82Ga single crystal shows a shape memory effect. It makes a thermo-elastic martensitic transformation at around 340 K, which is coincident with a Curie temperature. We made a synchrotron radiation white X-ray diffraction of the single crystal by changing the temperature from 400 K to 103 K. We observed the change of Laue spots following the transformation. As a result of experiment, the single crystal shows one cubic Heusler structure at 400 K. The direction of the crystal growth is along cubic [010] direction. In the process of decreasing temperature, many tetragonal structures with small volume of different axial direction become to appear. At room temperature the transformation almost finishes and two tetragonal Heusler structures which are twin each other remain. One of them is nearly the same as the structure at the beginning room temperature. The direction of the crystal growth is [010] of this tetragonal structure. We found
that the twinning plane of the tetragonal structure is (011) plane.
The Stability of Magnetic-Field-Induced Strain in a NiMnGa Ferromagnetic Shape Memory Alloy
Authors: Chen Feng , Gao Zhiyong , Cai Wei , Zhao Lian Cheng
Published: March 2009

The stability of magnetic field induced strain (MFIS) in Ni52Mn24Ga24 single crystal under temperature and magnetic field cycling is investigated and the corresponding micro-mechanism is also discussed. It shows that the saturated MFIS is very sensitive to temperature. Below martensitic transformation temperature(Tm), with increasing temperature, the saturated MFIS increases almost linearly. Besides, the saturated MFIS initially decreases with increasing the field cycling number less than four times, then does not change with further increasing the number of field cycles. The decrease of saturated MFIS can be attributed to the
decrease of twin boundary mobility, which is related to the crystal defect introduced by immigration of twin boundary under field cycling.
Effect of Heat Treatment on the Thermal Expansion Coefficient of Austempered Ductile Iron
Authors: Saidi M.Tadayon , Baghersaie N. , Varahram N.
Published: March 2009

Austempered ductile iron provide a unique combination of strength and toughness coupled with excellent design flexibility for automotive application as compared to forged or cast steels. Some material properties such as thermal expansion coefficient and its influence in final machining tolerance is a matter of discussion in the automotive industry. In this study the effect of heat treatment cycle on the microstructure & thermal expansion of ADI was investigated. Samples were austempered at 275 º C and 375 º C for one hour and then dilatometric test carried out in the temperature range of 50 °C to 350 °C, then the result was compared with the thermal expansion coefficient of forged steel. Microstructure and mechanical investigations were used to the assurance of these results. The results indicate that replacing of forged steel with ADI due to lower cost production and reduction in weight is possible if the correct tolerance were selected.
A Study on the Application of Ni-Ti Shape Memory Alloy as a Sensor
Authors: Nahm Seung Hoon , Kim Young Joo , Kim Jeong Min , Yoon Dong-Jin
Published: March 2009

When the shape memory alloy(SMA) completely consists of austenite phase that shows the super-elastic property, if the external energies, such as stress, crack, propagation and lamination, etc. are increased in this alloy until the austenite phase was transformed into the martensite phase, they are enough to change the mean free path of electrons correlated with the electrical resistivity of materials in the microscopic point of view. On the basis of the above concept, we carried out the feasible study for SMA wire as a strain sensor using the super-elastic property of SMA. The SMA wires of diameter 41 ㎛ were utilized for a sensor material. The relationship between electrical resistivity and tensile properties of the Ni-Ti based SMA wires during tensile loading was investigated. Since the strain is very sensitive to the minute change of electrical resistance of SMA wire, it is possible to use the SMA wire as a sensor of such physical quantities. In the study, the possibility for the application of Ni-Ti SMA wire as a sensor was investigated. The sensing system was able to measure the strain up to 6 % with 0.22 % measuring error. The sensitivity described by the ratio of electrical resistivity showed 0.00005.
Effects of Additional Reinforcing Fibers on the Interface Quality of SMA Wire/Epoxy Composites
Authors: Zheng Yan Jun , Cui Li Shan , Schrooten Jan
Published: March 2009

There are only limited ways to improve the interface bond strength of SMA wire reinforced composites. In this paper, the effect of the additional reinforcing fibers on the interface debond temperature of a TiNiCu wire reinforced epoxy matrix composite was studied. It was shown that the Kevlar fiber composite had a better interface between the TiNiCu wire and the epoxy matrix than that in the glass fiber composite. The negative thermal expansion coefficient of the Kevlar fibers were
thought to be beneficial for relieving the thermal stresses at the SMA/epoxy interface. From this angle of view, the Kevlar fiber composites are better candidates as the matrix of the SMA composites than the glass fiber composites.
On the Internal Friction of Ti50Ni25Cu25 Particle/Al Smart Composite
Authors: Shi P. , Cui Li Shan , Yang Da Zhi
Published: March 2009

The Ti50Ni25Cu25 particle/Al composite was fabricated with 30 vol.% Ti50Ni25Cu25
particles by hot pressing and followed by extruding methods. The internal friction (IF) measurements of the composite were carried out on an inverted torsion pendulum. Ti50Ni25Cu25 particles embedded in Al matrix improve the damping capacity of the composite. The internal friction behavior of Ti50Ni25Cu25 particles is consistent to that of the Ti50Ni25Cu25 bulk material. The mismatch of thermal
expansion coefficients between Ti50Ni25Cu25 and Al contributes to the damping capacity of the composite. A high damping capacity of the composite could be obtained at low vibration frequency and large vibration amplitude.
Development of Fe-Mn-Si-Cr Shape Memory Alloy Fiber Reinforced Plaster-Based Smart Composites
Authors: Wakatsuki Teppei , Watanabe Yoshimi , Okada Hiroshi
Published: March 2009

In previous studies, it has been found that the shape memory effect of the embedded
straight and wavy shape memory alloy (SMA) fibers enhance the strength and energy absorption prior to fracture of the composite, where the embedded SMA fibers shrink due to their shape memory effect. In the case of wavy fiber reinforced composites, the SMA fibers were subjected to pre-tensile strain using fiber holder with rotatable rollers to maintain the constant periodicity and amplitude of wavy fibers. In this study, on the other hand, the wavy SMA fibers were subjected to pre-tensile strain without using fiber holder, and therefore, periodicity and amplitude of wavy fibers were varied during the deformation. Then the wavy SMA fiber reinforced smart composite is fabricated. For the mechanical property characterization, three-point bending test is performed for the specimens.
Giant Magnetostrictive Actuator and Its Application in Active Vibration Control
Authors: Xu Hui Bin , Zhang Tian Li , Jiang Cheng Bao , Zhang Hu
Published: March 2009

TbDyFe is a rare earth-iron magnetostrictive alloy with “giant” magnetostrain, good magnetomechanical coupling factor and fast response. Giant magnetostrictive actuators (GMAs) are designed and fabricated with home-made TbDyFe rods. Their magnetostrain properties under varied operation are tested. The static output displacement up to 100μm and output force up to 1500N were obtained. The dynamic displacement increases with amplitude under fixed frequency and decreases with frequency under fixed amplitude generally. The maximum dynamic output displacement of 146µm was obtained at natural frequency around 5Hz. Active vibration control employing GMA was implemented in the flexible structure. The excellent damping effect, 20-30 dB under the frequency range from 10Hz to 100Hz was obtained. The dynamic phase delay of GMA has been analyzed. A
novel improved FSLMS algorithm is proposed to achieve a better control performance.
A Novel Smart Spring Concept for Helicopter Blade Vibration and Noise Suppression
Authors: Chen Yong , Wickramasinghe Viresh K. , Zimcik David G.
Published: March 2009

This paper demonstrates the ability of the Smart Spring to suppress helicopter blade
vibration through numerical simulation and experimental investigation. Mechanical shaker tests on a Bell-212 helicopter blade section verified the impedance control properties and the ability to suppress blade vibration using the Smart Spring proof-of-concept hardware. More importantly, the tests conducted in a wind tunnel proved the performance of the Smart Spring under highly varying unsteady excitation conditions. These tests confirmed that the Smart Spring system is able to actively suppress helicopter vibration through adaptive control of blade impedance properties.
Novel Properties of Nanostructured Metals
Authors: Lu K.
Published: March 2009

Due to the ultrafine grains (or domains or particles) and a high density of grain boundaries (or generally interfaces) in nanostructured materials, many properties and performance of the materials are expected to be significantly varied with respect to their coarse-grained counterparts. Extensive investigations over the past decays indicated that the nanostructured metals do possess some novel properties that may find technological applications in industry. In this talk, a brief survey of current status of investigations on properties of nanostructured metals will be summarized with emphasis on the following properties.
Research on the Model of the Magnetostrictive Actuator
Authors: Li Lin , Zhang Yuanyuan
Published: March 2009

One of the characteristics not to be ignored of the magnetostrictive material used in active vibration control is its hysteresis. In this paper this characteristic has been studied. At first a mathematical model of the hysteresis loop has been obtained on the basis of experiment. This model depends on the frequency and the amplitude of the alternating current inputted to magnetostrictive actuator. Then further modeling of the magnetostrictive actuator has been put forward.
Defects Distribution of Pr2Fe14B Hard Magnetic Magnet from Amorphous to Nanostructures Characterized by Positron Annihilation Spectroscopy
Authors: Wu Yu Cheng , Sprengel W. , Reimann K. , Reichle K.J. , Goll D. , Würschum R. , Schaefer Hans Eckhardt
Published: March 2009

The defect distributions have been investigated using positron lifetime spectroscopy on amorphous and nanocrystalline Pr2Fe14B samples, produced by melt-spinning and nanocrystallization route. The main two components can be concluded that were ascribed to vacancy-like defects in the intergranular layers or the interfaces, and microvoids or large free volumes with size compared to several missing atoms at the interactions of the atomic aggregates or the crystallites. The remarkable changes in the positron lifetimes from the amorphous structure to the nanocrystalline with varied sizes can be interpreted, indicating that the structural transformation and the grain growth induce the defect distribution changes occurring at the interfaces with different shape and size.
Magnetic Stability of Fe-Cr-Co Permanent Magnet Materials at High Temperature
Authors: Gao R.S. , Zhen L. , Shao Wen Zhu , Sun X.Y. , Zhu D.Y. , Xu R.G.
Published: March 2009

Magnetic stability of a Fe-Cr-Co permanent magnet material at high temperatures has been investigated. Changes of microstructures and hyperfine field distributions after high temperature holding were analyzed by transimission electron microscopy (TEM) and Mössbauer spectroscopy. The results of experiments indicate that the changes of magnetic properties of the Fe-Cr-Co alloy tend to decrease, and then gradually keeps a certain level with increasing the holding time at high
temperature. TEM observations show that microstructures of the alloy do not change distinctly after high temperature holding. Hyperfine interaction study through Mössbauer spectroscopy finds that the composition difference between α1 and α2 phases increases, and the composition of the two phases fluctuates. This study attributes the change of magnetic properties to element redistribution of Cr atom rather than the change of microstructure.
Effect of Mini Ga Doping in Nanocrystalline Nd4.5(Fe,Co)77.5B18 Magnet on Coercivity
Authors: Zhu Minggang , Zhang Jing Jing , Chen Wei , Li Xiu Mei , Dong Shengzhi , Li Wei
Published: March 2009

The microstructure and the coercivity of nanocomposite Nd4.5Fe76.5-xGaxCo1.0B18 (x=0~0.6at%)bonded magnets were studied. The results showed that addition of small amount of Ga in Nd4.5Fe76.5-xGaxCo1.0B18 made the grains finer and more uniform. A notable peak of coercivity was observed in the variational curve of coercivity with annealing time when Ga content was low (x=0.2). This phenomenon could be explained by the microstructure and the exchange coupling
interaction of two-phase nanocomposite.
The Effects of RE-Mg on Thermal Fatigue Resistance of Cast High Speed Steel (HSS) Rolls
Authors: Fu Han Guang , Jiang Zhi Qiang , Xing Jian Dong , Li Yan Xiang
Published: March 2009

The influence of rare earths(RE) and Mg compound modification on eutectic carbide morphology and matrix of high speed steel(HSS) roll was investigated. The results show that the matrix can be refined by the RE-Mg compound modifier, the eutectic carbides are inclined to turn into small lump, whose distribution is homogeneous. After modification, the heat conductivity coefficient of HSS is increased and heat expansion coefficient is decreased. Moreover, RE-Mg
modification is able to increase the cycles of thermal fatigue crack initiation and decrease the propagation rate. After cycling 700 times at the condition of heating at 600oC and cooling in 25oC water, the length of thermal fatigue crack is lessened by 41.12%.
Giant Magnetoimpedance in Fe89B4Hf7 Nanocrystalline Ribbons
Authors: Yu Xiaojun , Hu Ji Fan , Wang Dongling , Qin Hong Wei , Li Bo
Published: March 2009

In this work the giant magnetoimpedance effect has been found in Fe89B4Hf7
nanocrystalline ribbons. There is an optimal annealing temperature about 650°C for obtaining a large magnetoimpedance. The magnetoimpedance can reach 208% for Fe89B4Hf7 annealed at 650°C for 20min. meanwhile, it has been found that the magnetoimpedance in FeHfB shows a good thermal- heating stability, which is useful for application.
Effect of Thickness of Water Film on Atmospheric Corrosion Behavior of Carbon Steel
Authors: Hosoya Yuji , Shinohara Tadashi , Motoda Shin-ichi , Oshikawa Wataru
Published: March 2009

Atmospheric corrosion for carbon steel was discussed with taking notice of the relation between the corrosion rate, CR, and the thickness of adsorbed water film, d, onto deposited sea salt. Amount of water adsorbed onto sea salt was measured under various conditions of amount of deposited sea salt, Ws, and relative humidity, RH. Derived concentration of the solution film was compared with that calculated thermodynamically. Corrosion amount of carbon steel specimens exposed for a month under various Ws and RH was measured and CR along with d were obtained for each condition. The relations of CR to d had the same tendency as is found on “moist corrosion” and “wet corrosion” in Tomashov’s model; However, it showed a maximum CR = 0.29mm/y at d = 56µm, thicker than that reported by Tomashov.
Synthesis and Magnetic Properties of FeCo Alloy Nanoparticles by Hydrogen Plasma Metal Reaction
Authors: Leng Yonghua , Zhang Yaohua , Song Xu Bo , Li Xing Guo , Zhang Lefu
Published: March 2009

Fe61Co39 nanoparticles were prepared by hydrogen plasma metal reaction. The
as-synthesized nanoparticles were characterized by x-ray differaction (XRD), transimition electron microscope (TEM) and superconducting quantum interference device (SQUID). The nanoparticles are spherical in shape, have bcc structure with the mean particle diameter of 41 nm, and are basically
ferromagnetic with a slight amount of superparamagnetic part. The saturation magnetization and coercivity of the nanoparticles at 4.2 K are 190.15 emu/g and 1280 Oe, respectively. The blocking temperature is 250 K in 100 Oe and decreases with increasing the magnetic field.
Magnetic Entropy Changes in Ni54.9Mn20.5Ga24.6 Alloy
Authors: Wen Da , Zhang Ze Yu , Long Yi , Ye Rong Chang , Liu Zhuhong , Wu Guang Heng
Published: March 2009

Giant magnetocaloric effect based on first order phase transformation has been
investigated extensively recently. A considerable magnetic entropy change has been found in single crystal Ni52.6Mn23.1Ga24.3, Ni53Mn22Ga25 and polycrystal Ni51.5Mn22.7Ga25.8.This change originated from a sharp magnetization jump caused by the martensitic-austenitic structure transition on heating. In this paper, magnetocaloric effect in the alloys Ni54.9Mn20.5Ga24.6 is studied. The Curie point
temperature Tc of the alloy is adjusted to the vicinity of martensitic transition temperature Tm. The concurrence of martensitic structure transition and magnetic phase transition enhance the magnetocaloric effect in these alloys. The martensitic structure transition effect on the magnetic properties of the alloys is investigated. The character of magnetocaloric effect during the transition from the austenitic to martensitic state is discussed.
Magnetostrictive Properties of TbxDy1-xFey(x=0.3, 0.33; y=1.05, 1.36, 1.65) Composite Made by Directional Solidification and Polymer Infiltration
Authors: Kwon Oh Yeoul , Kim Jong Chul , Kwon Young Dong , Yang Dae Jin , Lee Se Hoon , Lee Zin Hyoung
Published: March 2009

In this paper, composites with Tb:Dy ratio of 0.30:0.70 and 0.33:0.67 were fabricated by polymer infiltration method. Both maximum d33 and strain of composites with different Tb/Dy ratio (0.33:0.67, 0.30:0.70) were investigated as a function of the volume fraction of RFe2 phase. The maximum d33 and the strain of composites with higher Tb:Dy ratio (higher magnetocrystalline anisotropy) showed higher than that of composites with lower one as volume fraction of RFe2 increased.
Dynamics of Magnetization Reversal in Thin Polycrystalline Co Films
Authors: Lai Heng , Huang Zhi Gao , Gai Rongquan , Chen Shui Yuan , Du You Wei
Published: March 2009

The thin polycrystalline Co films with different annealed time were prepared by
magnetron sputtering method. XRD and hysteresis loops of the samples were measured. A mean field equation with Heisenberg model for calculating dynamic scaling was derived. The experimental and simulated results indicate that, the scaling law, A=A0+H0 a ω b, describes well dynamic magnetization along easy and hard axes for the anisotropy magnetic films; the anisotropy scaling exponents exist clearly in the anisotropy films; the simulated results are consistent with the experimental those.
Effects of HA/TiN Coated Film on the Surface Activation of Bone Plate Alloys
Authors: Choe Han Cheol , Ko Yeong Mu
Published: March 2009

In this study, in order to fabricate dental and medical bone plates, the effects of
hydroxyapatite(HA) coating made of tooth ash and TiN coating prepared by electron-beam physical vapor deposition(EB-PVD) method on corrosion resistance and surface phenomena of Ti alloyed bone plates were investigated using various test methods. The coatings were deposited on the Ti-6Al-4V alloy fabricated by using a vacuum induction furnace. The corrosion behaviors of the
samples were examined through potentiodynamic method in 0.9% NaCl solutions at 36.5±1°C and corrosion surface was observed using SEM and XPS. The surface roughness of TiN coated bone plates was lower than that of HA coated plates. The
structure of TiN and HA coated layers showed the columnar structure. The corrosion potential was observed to be higher on the TiN and HA coated specimens than that of the non-coated alloy. The active current density was drastically lowered by both of TiN and HA coatings. The pit number and pit size of TiN and HA coated alloy were smaller in comparison with those of non-coated alloy. From the experimental results, it is suggested that TiN coated Ti alloy sample with rough surface has good protective propertiy against corrosion as well as HA coated bone plate alloy.
Microstructures and Elastic Moduli of Binary Titanium Alloys Containing Biocompatible Alloying Elements
Authors: Jeong Hi Won , Kim Seung Eon , Hyun Yong Taek , Lee Yont Tai , Park Joong Kuen
Published: March 2009

New titanium alloys with a low elastic modulus have been developed for biomedical
applications to avoid the stress shielding effect of an artificial prosthesis. The newly developed alloys contained the transition elements like Zr, Hf, Nb, Ta which were non-cytotoxicity elements and β stabilizers. In the present paper the elastic moduli of Ti-xM containing Zr, Hf, Nb, Ta were evaluated by measuring the velocity of supersonic wave (Pulse Echo Overlap). The effectiveness of the alloying elements for lowering the elastic modulus was investigated. In addition, the dominant factors for the low modulus were discussed. Ta was the most effective in lowering the elastic modulus of the alloys. The effectiveness of Hf was not acceptable for decreasing the elastic modulus. The dominant factor was the lattice parameter for Zr, and the poisson's ratio for Nb, Ta, respectively, in lowering the elastic modulus of Ti.
High Temperature Deformation Behavior of a Beta Titanium Alloy for Biomedical Application
Authors: Zhou Qing , Itoh Goroh , Hasegawa Hisashi , Motohashi Yoshinobu , Niinomi Mitsuo
Published: March 2009

The deformation characteristics of a beta-type Ti-29%Nb-13%Ta-5%Zr alloy, developed for biomedical application, and their relation with the microstructure are investigated. The cold-rolled specimen is subjected to a tensile test at high temperatures ranging from 700 to 800°C under a constant cross-head speed ranging from 1×10-4 to 1×10-2s-1. The elongations tested at different temperatures are compared with that of Ti-15%V-3%Cr-3%Sn-3%Al, a typical beta titanium alloy. The deformation mechanism is characterized from the parameter of the strain rate
sensitivity. The microstructures before and after the tensile test are observed with optical microscope and the correspondent grain sizes are measured. The grain growth during the deformation is also described.
Mechanical Properties of Ti-Nb Biomedical Shape Memory Alloys Containing 13- and 14-Group Elements
Authors: Hosoda Hideki , Fukui Yusuke , Inamura Tomonari , Wakashima Kenji , Miyazaki Shuichi
Published: March 2009

In order to replace Ti-Ni shape memory alloys, new biomedical shape memory alloys
have been developed which are composed of beta titanium and nontoxic elements only. In this paper, experimental results of mechanical and shape memory properties are reported for the Ni-free Ti-18mol%Nb shape memory alloys containing 3mol% of 13-group and 14-group ternary elements in the periodic table. The ternary elements selected are Al, Ga, In, Ge and Sn. It was found that the solution treated alloys exhibit good shape memory effect but almost no pseudoelasticity at room temperature. Ultimate tensile strength and elongation to failure at room temperature are ranged from 250 to 710MPa and from 13 to 21%, respectively, depending on the kind of ternary elements. Effect of solution hardening on strength is discussed.
Wear Loss and Elution of C.P.Ti and Titanium Alloys in Simulated Body Fluids
Authors: Ueda Kyosuke , Narushima Takayuki , Ouchi Chiaki , Iguchi Yasutaka
Published: March 2009

Wear behavior of titanium materials such as C.P.Ti, Ti-6Al-4V and Ti-6Al-7Nb, was
studied in simulated body fluids by means of the pin-on-disk type wear testing. The mass loss in wear testing increased with increasing the sliding distance. The a+b type titanium alloys, Ti-6Al-4V and Ti-6Al-7Nb, exhibited higher wear resistance than the C.P.Ti. Average size of the wear debris was 4.5 µm and 3.7 µm for C.P.Ti and the a+b type titanium alloys, respectively. The elution of metallic constituents into 1 mass% lactic acid solution was detected after the wear test.
Gene Expressions Induced by Calcium Phosphate Ceramics after Implantation into the Muscle of Rat
Authors: Xu Jin Rui , Fan Hong Song , Tan Yan Fei , Zhang Xing Dong
Published: March 2009

The osteoinductivity of calcium phosphate ceramics has been studied extensively, but the mechanism is still unclear and few reports about the molecular mechanism in the osteoinductive process. In this study the osteoblast related gene expressions induced by biomaterials were investigated by isolating the RNA from the tissue grown in porous hydroxyapatite/tricalcium phosphate (HA/TCP) ceramics implanted in rat femur muscle on day 7, 15, 30, 60, 90,120, and analyzed by RT-PCR technique. RNA extracted from muscle without implant was used as control at
the same time. The results showed that osteopontin and osteocalcin genes, the important osteoblastic markers, expressed in early stage, on day 7 after implantation, and were detected at any period. Collagen type I gene expressed on day 60, 90 and 120. It revealed that osteoblast differentiation occurred very early before collagen type I expression after implanting HA/TCP ceramics in vivo.
Improving the Interconnectivity of Chitin-Gel-Cast Porous Calcium Phosphate Ceramics by Different Acid Etching Approaches
Authors: Liang Lie Feng , Weng Jie , Feng Bo , Qu Shao Xing
Published: March 2009

Porous blocks of bioactive ceramics are a more preferable tissue substitute to replace and reconstruct the defected tissues in that their interconnective pores are beneficial to new tissue ingrowth. The most important specification requires the controlled interconnective pores with required mechanical strength. A novel chitin-gel-cast approach is utilized to prepare porous bioceramic blocks. In order to improve their interconnection of pores, several acids are selected to etch the windows between porous. Light microscope (LM) and Scanning electronic microscope (SEM) are used to investigate the etching effect on the windows and walls of porous blocks. The results show that the acid etching can improve the interconnection of porous blocks with slight decrease of compressive strength under carefully controlled process conditions.
Study on Plasma Sprayed Calcium Silicate Coatings
Authors: Zheng Xue Bin , Liu Xuan Yong , Xue Wei Chang , Ding Chuan Xian
Published: March 2009

Wollastonite and dicalcium silicate coatings have been prepared on Ti-6Al-4V substrate via plasma spraying. Bond strength test, simulated body fluid (SBF) immersion, in vitro cell culturing, and in vivo implantation were carried out to evaluate their mechanical and biological characteristics. The results obtained showed that both coatings possess higher bond strength as compared with hydroxyapatite (HA) coating. In the meanwhile, the good bioactivity and biocompatibility were confirmed in this study.
The Influence of Calcium at the Titanium Surface on Co-Precipitation of Ca-P and Bovine Serum Albumin
Authors: Feng Bo , Weng Jie , Qu Shao Xing , Zhang Xing Dong
Published: March 2009

The influence of calcium (Ca) at titanium surface on co-precipitation of Ca-P and bovine serum albumin (BSA) has been investigated by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The titanium surface containing Ca was prepared by immersing titanium plates into a saturated calcium hydroxyl (Ca(OH)2) solution. A solution containing BSA, calcium and phosphate ions was used for the co-precipitation test. Both BSA and calcium
phosphate co-precipitated onto titanium surfaces with and without Ca. For the former, however, a thicker carbonate apatite coating, which consisted of finer crystal grains, formed and more protein precipitated compared to the surface without Ca. These results indicated that Ca at the titanium surface was favorable to the co-precipitation of BSA and Ca-P. Moreover, chemical interactions probably
occurred during the co-precipitation of BSA and Ca-P.
Compare of Electrospinning PLA and PLA/β-TCP Scaffold in Vitro
Authors: Fan Hong Song , Wen Xian Tao , Tan Yan Fei , Wang R. , Cao H.D. , Zhang Xing Dong
Published: March 2009

In recent years, electrospinning process is gradually applied in producing
tissue-engineering scaffold. In this study, we chose polylacticacid(PLA) and β-tertiary calcium phosphate(β-TCP) as raw materials to fabricate PLA/β-TCP biodegradable composite scaffold by electrospinning process. The characteristics of the scaffold and effect of the scaffolds to cell proliferation and cell adhesion was studied. Compare with pure PLA scaffold, blendingβ-TCP in the spinning process of the scaffold could improve the properties of the scaffold, especially the hydrophilicity and the proliferation and adhesion of cells, this means that the material is more potential to be used as tissue engineering scaffolds.
Response of Human Osteoblast-Like Cells and Fibroblasts to Titanium Alloy Nitrided under Glow Discharge Conditions
Authors: Czarnowska E. , Sowinska A. , Cukrowska B. , Sobiecki Jerzy Robert , Wierzchoń Tadeusz
Published: March 2009

Cell adhesion to biomaterials and cell proliferation are affected, among others, by the
chemical composition and surface microtopography of the biomaterial. These are, in turn, influenced by sterilisation processes. The aim of this study was to evaluate the sensitivity of osteoblasts and fibroblasts to TiN surfaces deprived of an oxide film or with an enhanced oxide film due to sterilisation in plasma or in an autoclave, respectively. Type TiN+T2N+aTi(N) nitrided surface layers were produced under glow discharge conditions and sterilized in plasma Sterrad 100 and in a steam autoclave. The results provide evidence that nitrided surface layers improved wearand corrosion resistance of the titanium alloy and that these features were not influenced by sterilisation procedures that resulted in various oxide films. In vitro study of human fibroblast and osteoblast-like cells cultured on TiN surfaces modified by sterilisation processes showed that cells respond to the presence of an enhanced oxide film by aggregating, exhibiting lower viability and increased apoptosis, while to a surface deprived of oxides, by regular spreading and high viability. It can be concluded that differences in surface composition and topography of the nitrided surface layers due to various types of sterilisation elicit specific cell responses, and plasma sterilisation seems to be optimal for bone implants with this surface layer.
The Study of Apoptosis and Phagocytosis of Rabbit Synoviocytes Induced by Particulate Joint Replacement Materials
Authors: Yung Che Ting , Lian Shuang Shii , Sung Y.J.
Published: March 2009

Synoviocyte is one of the cells in direct contact with the wear particles and the role of synoviocytes in the prosthesis loosening remains to be further understood. The purpose of the present study is to investigate whether particulate biomaterials cause synoviocyte dead or simply activate these cells. The activation of synoviocyte in response to particulate biomaterial exposure will be indicated with its phagocytotic ability. As to the effects of particulate biomaterials to apoptosis will
be tested on rabbit synoviocytes, HIG-82 cells. The results demonstrate that the addition of cobalt particles would lead the HIG-82 cells to apoptosis and apoptosis accompanying caspase3 cleavage, which means that apoptosis of the HIG-82 cells resulted from the addition of cobalt particles might went through caspase-dependent pathway. On the other hand, exposing to nonmetal particles such as TiO2 and SiO2, particles did not provoke apoptosis of the HIG-82 cells. TiO2 particles activated the cells and were phagocytosed by the HIG-82 synoviocytes, no significant biological effects were found while the HIG-82 cells exposed to SiO2 particles.
Study of Nano-Hydroxyapatite on the Remineralization of Dismineralized Teeth
Authors: Meng Xiang Cai , Li Xing Yi , Lu Kui Long
Published: March 2009

The hydroxyapatite (HA) particle with different morphologies were prepared by adding a certain additive into Ca(H2PO4)2·H2O and controlling the bathing and sintering temperature, and the pure needle-like HA sol were obtained when the bathing temperature was 70°C. The experimental results show that the degree of crystallization of HA increase and the particles tend to accumulate with increasing of the drying and sintering temperatures. The particles of HA were spheroid, which
diameters were of less than 100nm when they were sintered at the temperature of 700°C. The effect of nano-hydroxyapatite on remineralization of early enamel caries were studied too. The hardness of dismineralized enamel was increased when dismineralized enamel was remineralized by nano-hydroxyapatite. The SEM analysis shows that the interspace of enamel surface were decreased and the many mineral salts were sedimentated, which indicated that the nano-hydroxyapatie could promote remineralization for the dismineralized enamel.
Hydrogenation Properties of Mg-Co and Its Related Alloys
Authors: Zhang Y. , Tsushio Y. , Enoki Hirotoshi , Akiba Etsuo
Published: March 2009

Novel Mg-Co binary alloys with BCC (body-centered cubic) structure have been
successfully synthesized by means of mechanical alloying technique. The formation of BCC structure was confirmed by X-ray diffraction and transmission electron microscopy. Mg-Co alloys were found in the range of Co concentration between 37 and 80 atomic %. All the Mg-Co alloys synthesized absorbed hydrogen below 373K. The maximum hydrogen capacity of these alloys reaches 2.7 mass %. However, desorption of hydrogen at 373 K has not been observed yet. Mg- Co-X (X = B and Ni) ternary alloys with BCC structure have also been synthesized. The lattice
parameter of both alloys is lower than that of Mg-Co binary alloys, meanwhile the maximum hydrogen content of both alloys also decreased.
A Study on Hydrogen Desorption Properties of Multiwall Carbon Nanotubes
Authors: Lee Jai Young , Lee Ho , Kim Hyun Seok
Published: March 2009

Hydrogen desorption properties in multiwall carbon nanotubes(MWNTs) were
investigated from the view points of not only physical hydrogen molecules adsorption in nano-hole but also chemical hydrogen adsorption on graphite surface. MWNTs with intrinsic closed structure having the blocked hole and MWNTs with open structure were studied through hydrogen thermal desorption technique equipped with gas chromatograph. In order to grow MWNTs with open structure, novel method using oxygen added plasma(CH4/H2/O2) has been introduced. The structure of MWNTs was gradually changed with increasing oxygen addition amount, showing aligned MWNTs bundles and open tube cap at 10% oxygen addition. The precise analysis on thermal desorption spectra on MWNTs with closed structure showed that hydrogen gas was released at three major temperature ranges such as 100-230K, 290-350K, and 600-625K, where the evolved hydrogen amounts were about 1.65wt%, 0.64wt%, and 0.03wt%, respectively. However, in case of aligned and open MWNTs, the evolution peak around 290-350K was highly developed (about 1.9wt%) and the desorption peak at 600-625K was disappeared. The hydrogen desorption activation energy was also
calculated. The obtained hydrogen desorption activation energy of MWNTs with closed and open structure at ambient temperature was -18.5kJ/mol H2 and 16.5kJ/molH2, respectively. The hydrogen desorbed between 290 and 330K in MWNTs with open structure was the hydrogen physi-sorbed in nano-hole. And Ni-doping (dispersion) effect on hydrogen storage properties was investigated
comparatively. Ni nano-catalysts were expected to effectively dissociate hydrogen molecules in gas phase, providing atomic hydrogen possible to form chemical bonding on carbon surface. The metal nanoparticles were homogeneously dispersed using incipient wetness impregnation method. Hydrogen desorption spectra of MWNTs with Ni nanoparticles showed that about 2.8wt% of hydrogen was released in the range of 340-520K.
Hydrogen-Induced Amorphization in C15 Laves Phase DyCo2 Studied by Pressure Calorimetry
Authors: Li H.-W. , Ishikawa Kazuhiro , Aoki Kiyoshi
Published: March 2009

Structural changes in C15 Laves phase DyCo2 on heating using a pressure differential scanning calorimeter (PDSC) in a hydrogen atmosphere between 0.1 and 5.0 MPa were investigated by a powder X-ray diffractometer (XRD), a differential scanning calorimeter under an argon flow atmosphere (Ar-DSC), a
transmission electron microscope (TEM) and a hydrogen analyzer. As the temperature of DyCo2 increases, the reactions such as hydrogen absorption in a crystalline state, HIA (hydrogen-induced amorphization), precipitation of DyH3 and decomposition of the remaining amorphous phase into β-Co + DyH3 occurred
exothermically for every hydrogen pressure. The mechanism of HIA in DyCo2 is discussed on the basis of the experimental results.
Relationship between Palladium Morphology and Thermodynamics in Palladium-Hydrogen System
Authors: Tang Tao , Guo Shu-Ian , Lu Guang-da
Published: March 2009

The pressure-composition (P-C) isotherms of protium and deuterium in Pd sponge particles have been measured over a temperature range from 278K to 323K. Based on these data and combined with literature data, the relationship between the Pd crystal type, particle size and thermodynamic properties in the Pd-H system was investigated. The saturation solubility of hydrogen in solid solution
region ( a-phase) and the absorption plateau pressure increase with the decreasing Pd particle size at ambient temperature, but the desorption plateau pressure does not change with Pd morphology. The effect of Pd morphology on above two parameters gets weaker at higher temperature and the difference of plateau pressure among several different Pd morphologies disappears at higher
temperature, such as 373K. The absolute value of phase transformation enthalpy and entropy from solid solution phase to hydride phase decrease with the decreasing particle size of Pd, but which are the smallest in single crystal Pd. The degree of hysteresis effect in Pd-H system depends on the background density in the sample, so it is the strongest in Pd sponge.
Hydrogen Storage Intermetallic Compounds: First Principles Investigations of Properties Relevant to Applications
Authors: Gupta Michèle , Crivello Jean Claude
Published: March 2009

Quantum mechanical calculations of the electronic structure of hydrogen storage
materials have undoubtly deepened our fundamental understanding of their basic properties. In addition, ab-initio calculations can provide a useful insight on the hydrogen storage properties that are crucial for applications. In this paper, we focuss on the latter aspects, we discuss the electronic and elastic properties of Haucke compounds of AB5 type (A=La or Y, B=Ni), in relation with their hydrogen absorption properties. The effects of substitutions of Ni by an s element of the 3d series, Cu, as well as by s-p elements of the IIIA (Al) and IVA series (Si, Ge, Sn) for several substitution rates are presented. and discussed in light of available experimental data on electronic, thermodynamic and elastic properties.
High-Temperature Characteristics of Melt-Spun Hydrogen Storage Alloys
Authors: Li Rong , Wu Jianmin , Qi Yan , Zhou Shaoxiong
Published: March 2009

In this work, the electrochemical discharge capacity of melt-spun (MmY)1 (NiCoMnAl)5 ribbons, in which the content of yttrium was 0-2.5wt%, was studied in the temperature range of 30~80oC. It was found that adding element yttrium made the electrochemical capacity of the compounds increased. The capacity obtained was 333mAh/g at 30 oC and 247 mAh/g at 80oC when the content of yttrium was 2.0wt%. In addition, 70~85% recovery of the capacity was obtained due to better antioxidation. The increase of charging/discharging efficiency with yttrium substitution for Mm in melt-spun ribbons illustrated by the potential characteristics of charging/discharging is ascribed to the flatter and lower hydride formation potential, as well as the higher hydrogen evolution potential. Moreover, This effect is more prominent with increasing yttrium content.
Property Changes of Some Hydrogen Storage Alloys upon Hydrogen Absorption-Desorption Cycling
Authors: Park Choong-N. , Cho Sung-W. , Choi Jeon
Published: March 2009

Hydrogen absorption-desorption cycling induced by pressure change in a closed system were carried out with LaNi5, La0.7Ce0.3Ni4Cu and TiFe0.9Ni0.1 alloys. PC isotherms measured during the cycling showed some changes in hydrogen storage capacity, plateau pressure and hysteresis of the alloys. . The half capacity life of LaNi5 alloy can be projected as 70,000 cycles for room temperature pressure cycling. When La0.7Ce0.3Ni4Cu alloy was pressure cycled both of the plateau pressures were decreased significantly and continuously. TiFe0.9Ni0.1 alloy showed a good resistance to cyclic degradation. Heat treatments of the degraded alloys under 1 atm of hydrogen gas recovered most of the hydrogen storage properties to the initial level even though they were degraded again more rapidly
upon subsequent cycling.
Synthesis and Crystal Structure of New Hydrides in Mg-RE Systems under High-Pressure (RE = La, Ce, Pr)
Authors: Goto Yasuyuki , Kakuta Hirofumi , Kamegawa Atsunori , Takamura Hitoshi , Okada Masuo
Published: March 2009

The high-pressure synthesis of new hydrides of Mg-RE-H systems, where RE = La, Ce and Pr, were conducted by using a cubic-anvil-type apparatus, and their crystal structure, thermal stabilities and hydrogen contents were investigated. In MgH2-xmol%REH (REH = LaH3, CeH2.5 and PrH3), new hydrides with primitive tetragonal structure were synthesized around x = 25 - 33 under GPa-order high pressures. The lattice constants were a = 0.8193 nm, c = 0.5028 nm, a = 0.8118 nm, c = 0.4979 nm and a = 0.8058 nm, c= 0.4970 nm at x = 25 in Mg-La, Ce and Pr systems, respectively. The hydrogen contents of the novel compounds were 4.1 mass%, 3.7 mass% and 3.9 mass% in Mg-La, Ce and Pr systems, respectively, and the chemical formulas were found to correspond to Mg3LaH9, Mg3CeH8.1 and Mg3PrH9. The new hydrides decomposed into Mg and rare-earth hydride at about 600 K (Mg3LaH9: 614 K, Mg3CeH8.1: 609 K, Mg3PrH9: 630 K) with an endothermic reaction.
Centrifugal Casting Practice and Microstructure and Mechanical Properties of a 2205 Duplex Stainless Steel
Authors: Lee Sang Mok , Yang S. , Kim S.T. , Park Y.S. , Moon B.M.
Published: March 2009

Microstructural features, mechanical properties, and corrosion properties of a SAF2205 duplex stainless steel (DSS) were systematically investigated as functions of cooling rate during casting and heat treatment conditions. The choice of a duplex stainless steel was a SAF2205 alloy, of which composition is 0.03C, 21~23Cr, 4.5~6.5Ni, 2.5~3.5Mo, 0.08~0.2N, 1.0Si, and 2.0Mn with remaining Fe. A 5-stepped sand mold and the permanent Y-block mold were used to check the effect
of cooling rate during solidification. The microstructural characteristics, such as grain size, the d/γ ratio, the existence of the carbides and σ phase has been noticed to greatly change with the variation of cooling rate during the casting procedure. Various heat treatment conditions were also examined to achieve the optimized mechanical properties of DSS. Based on the preliminary examination, the
feasibility study of utilization of centrifugal casting has been carried out for the production of better quality DSS pipe components. Melting and casting practices of DSS during centrifugal casting in an air atmosphere were systematically investigated in order to obtain the optimized process parameters.
Interactive Mechanisms of Sulfide Inclusions and Environmental Factors in Low Cycle Fatigue Process of Pressure Vessel Steels in High Temperature Water
Authors: Wu Xin Qiang
Published: March 2009

Low cycle fatigue tests were conducted in high temperature water for A533B pressure vessel steels with sulfur contents of 0.013, 0.025 and 0.038 wt.% respectively. Cyclic stress amplitude response and fatigue resistance as well as influence of strain rate, temperature and dissolved oxygen concentration in water were investigated. Fatigue cracking/fractograhpic features were examined. Sulfide-related environmentally assisted cracking mechanism is discussed.
Investigation of Protective Cover Gas Mixtures for Prevention of Melt Ignition during Magnesium Alloy Melting
Authors: Ha Won , Lee Jae-Eon , Kim Young Jig
Published: March 2009

In this study, melt protection property of SF6+synthetic air and HFC-134a+synthetic air cover gas mixtures were investigated for most commonly used magnesium alloys, AZ91D and AM60B. Each alloy was melted in mild steel crucible with different temperature, cover gas concentrations and sealing conditions. HFC-134a+synthetic air cover gas mixtures offered better melt protection property for all variables of temperatures, alloys, cover gas concentrations and sealing conditions. However, crucible (AISI 1020) surface that is exposed to HFC-134a cover gas mixtures was seriously damaged due to the corrosive characteristics of HFC-134a in molten
magnesium temperature.
Investment Casting of Near-Net Shape Gamma Titanium Aluminide Automotive Turbocharger Rotor
Authors: Kim Myoung Gyun , Sung Si Young , Lee Gyu Chang , Park Joon Pyo , Kim Young Jig
Published: March 2009

The objective of this study was to optimize the casting design of gamma titanium aluminde automotive turbocharger rotor by means of the practical experiment and numerical simulation. Gamma titanium aluminide rotors were produced by centrifugal casting methods on a laboratory scale. Based on the metal-mold reaction of gamma titanium aluminide, the investment molds were manufactured by an electro-fused Al2O3 mold. The experimental results showed that the castings failed to reach the end of the cavities due to insufficient centrifugal force and a lower fluidity compared to the other metals. Although the satisfactory results were not obtained in the numerical simulation, it was concluded that numerical simulation aided to achieve understanding of the casting process and defect formation in gamma titanium aluminide turbocharger rotor castings.
Morphology of Primary Silicon and its Growth Mechanism in Hypereutectic Al-Si Alloys during Melt Overheating Treatment
Authors: Zhang Rong , Zhao Zhi Long , Huang Tai Wen , Liu Lin
Published: March 2009

The relationships between the morphologies of primary silicon and undissolved silicon particles in melt of Al-Si hypereutectic alloys are studied by holding the melt from 600 to 1100°C and then quench interrupting. The variation of growth process and mechanism of primary silicon is also investigated. The results show that undissolved silicon particles in the melt would become the nuclei of primary silicon precipitated in solidification and there is a close relationship between the shape of primary silicon and undissolved silicon particles. The growth of silicon would follow not only twin plane re-entrant edge (TPRE), but also layer mechanism as well. Meanwhile, the shape of primary silicon also relied on kinetic surroundings, such as solute transportation. At higher overheating temperatures of the melt, the primary silicon takes star-like and tree-like shapes.