bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self-Reinforced Bioactive Glass-Bioabsorbable Polymer Composites
Authors: Niiranen Henna , Törmälä Pertti 
Published: April 2011

AbstractNon-reinforced and self-reinforced bioactive-bioabsorbable composite rods were produced by extrusion and solid state die-drawing using P(L/DL)LA matrix and spherical glass particles. The structure and mechanical properties of composites were measured before and after die-drawing. The structure examination of composites by SEM showed the formation of fibrous reinforced structure of the polymer with spindle-shaped pores around the glass spheres during and oriented in the direction of die-drawing. Incorporation of glass into the polymer matrix turns the composite more brittle compared to neat polymer. By die-drawing the brittleness of the composite can be eliminated.Not only the bioactivity and controlled degradation rate of composite but also structure and mechanical properties achieved during die-drawing make the self-reinforced bioactive glass- bioabsorbable polymer composites a novel implant material for temporary support of healing tissues.
Microstructural Investigation of the Oxide Scale on Zr-2.5NB and its Interface with the Alloy Substrate
Authors: Benezra V. , Mangin S. , Treska M. , Spector M. , Hunter G. , Hobbs L.W. 
Published: April 2011

AbstractOxidized Zr-2.5Nb is being developed as an articular bearing surface for the femoral component in total joint arthroplasty. It has so far demonstrated superior wear performance against ultrahigh molecular weight polyethylene (UHMWPE) with respect to traditional articulating materials such as Co-Cr-Mo alloys. In this investigation, we used thermogravimetric analysis, transmission electron microscopy, and in situ x-ray diffraction techniques to study the microstructure and stress state of the oxide scale grown on Zr-2.5Nb.The oxidation temperature not only determines the kinetics of oxidation but the morphology of the various oxidation products. We have identified the oxidation products of both phases of the two phase alloy and correlated them with the original alloy microstructure. These include not only monoclinic zirconia but also small amounts of tetragonal zirconia and a mixed oxide phase combining both zirconium and niobium. The alloy microstructure both influences the final oxidation products and is reflected in the microstructure of the oxide. The oxide scale itself has a predominantly columnar microstructure which extends from the oxide/metal interface to the outer surface of the oxide. In situ x-ray diffraction measurements revealed that the oxide scale is stressed in compression following cooling and exhibits strong crystallographic texture. The oxide/metal interface is continuous, without pores or voids which might be detrimental to oxide adhesion. In addition, we have identified a phase which develops at the interface between the beta-zirconium grains and the oxide. We have also identified amorphous regions within the oxide scale which serve as sinks for silicon and other impurity elements found in the alloy.
Rapid Depth-Resolved Analysis of Nitride Layers (>50 Micrometers) on Prosthetic Devices by Radio Frequency Glow Discharge Atomic Emission Spectroscopy
Authors: Kenneth R. , Hartenstein Matthew L. , Compton Richard , Shetty Ravi 
Published: April 2011

AbstractThe ability to provide depth-resolved chemical information is an important attribute for analytical methods employed in the biomaterials laboratory, both research and production. Radio frequency glow discharge atomic emission spectroscopy (rf-GD-AES) is shown to provide profiles of nitrogen content in prosthetic alloys to depths of greater than 50 micrometers, with analysis times of less than 30 minutes.
Synthesis and Characterization of Calcium Phosphate Coatings by Metalorganic Chemical Vapor Deposition
Authors: Gao Y. 
Published: April 2011

AbstractThin coatings of various calcium phosphates including tricalcium phosphate (TCP), calcium pyrophosphate, and hydroxyapatite were synthesized by plasma-enhanced metalorganic chemical vapor deposition (MOCVD). Structure, composition, and surface morphology of the coatings were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. All coatings were very dense and free of cracks. X- ray diffraction showed that the as-grown coatings with the Ca/P ratio of 1.5±0.5 and 1.0±0.5 were crystalline μ- TCP and pyrophosphate, respectively. However, hydroxyapatite coatings with the Ca/P ratio of ∼1.67 were amorphous. The crystalline μ-TCP and pyrophosphate coatings exhibited strong growth texture. The textured orientations varied with different growth temperatures. In addition, the microstructure of the μ-TCP coatings strongly depended on the growth temperatures.
Optimising of the Physico-Chemical Properties of a Novel Barium Sulphate Preparation for the X-Ray Examination of the Intestine
Authors: Laermann Barbara , O'Brien Paul , Bartrama Clive 
Published: April 2011

AbstractNovel barium sulphate preparations for X-ray contrasting with defined rheological properties have been developed which provide both low viscosity and high density. The relationship between volume fraction and both high-shear and low-shear viscosity was investigated to obtain the relative viscosity [η] and the limiting packing fraction Φm. The particles in a good preparation have a hydrophilic surface which allows the particles to penetrate through the mucus layer of the gastro-intestinal tract. Adsorption isotherms for chondroitin sulphate on barium sulphate from aqueous solution have been determined by spectrophotometry. FTIR spectroscopy and SEM has been used to analyse adsorption behaviour at a molecular level. Coating studies on mouse intestinal mucosa were carried out. A model for testing the coating thickness and particle packing of proprietary and test suspensions was developed. Surface and cross-sections characterisation of a novel test preparation on the intestinal model were determined using cryo scanning electron microscopy. In order to test the resolution obtained with novel material a phantom has been developed.
Mechanical Properties of Zr-Al-Cu-Ni Alloy Glass at Different Quenching Condition
Authors: Yabe H. , Toyoshima R. , Hiraiwa Y. , Oguri K. , Miyazawa Y. , Nishi Y. 
Published: April 2011

AbstractThe samples of Zr56Al9Cu5Ni30 alloy were prepared by liquid-quenching. The mechanical properties depend on the cooling condition. The Hv value (25g load) is 580 for slow cooled rate sample, whereas the Hv value is over 800 for fast cooled sample. Since the fast cooling enhances the sample hardness, these samples become brittle. The brittleness is evaluated by the critical deformation energy (Ec) of collapse.
The Shear Modulus of Glassy and Supercooled Liquid Pd40Ni40P20
Authors: Bains A. S. , Gordon C. A. , Granato A. V. , Schwarz R. B. 
Published: April 2011

AbstractWe have measured the shear modulus and its temperature dependence of Pd40Ni40P20 using an EMAT technique. The room temperature value of 3.92(1011) d/cm2 is in fair agreement with that of 3.66(1011) d/cm2 given earlier by He and Schwarz, using a resonant ultrasound spectroscopy technique. The relative change with temperature coefficient for T << Tg is 3.4(10−4) K−1. For the heating rate of ∼1 K/min used here, Tg = 565 K compared with a value of 575 K reported earlier. The shear modulus is continuous at Tg , but its temperature coefficient is larger by a factor of 6.5 for T >> Tg. During temperature cycling near but below Tg , irreversible aging effects are found showing that the amorphous state is not an equilibrium state. Near but above Tg, the cycling effects are reversible for time scales of the order of hours but not for time scales of the order of days, showing that metastable equilibrium states have not yet been fully attained. The results are in overall agreement with the predictions of the Interstitialcy Theory.
Significant Undercooled Liquid Region of Over 200K in Rare Earth Based Metallic Glasses
Authors: Lu Z. P. , Li Y. , Ng S. C. , Feng Y. P. 
Published: April 2011

AbstractUsing a newly developed temperature modulated differential scanning calorimetry (TMDSC), glass transition has been detected in several RE-Fe-Al (RE = ND, Pr, Sm and Y) metallic glasses, which can not be observed by a conventional DSC. Our results show that the glass transition occurred together with a small fraction crystallization in the as-spun samples, the final main crystallization transition occurred at higher temperature (over 720K) in these rare-earth based alloys. Large undercooled liquid regions up to 200K at a underlying heating rate of 5K/min have been observed in these glasses.
Viscosity, Relaxation and Crystallization Kinetics In Zr-Ti-Cu-Ni-Be Strong Bulk Metallic Glass Forming Liquids
Authors: Busch Ralf , Masuhr Andreas , Bakke Eric , Waniuk T. Andy , Johnson William L. 
Published: April 2011

AbstractThe high thermal stability of bulk metallic glass (BMG) forming liquids in the undercooled state allows for measurements of thermophysical properties in a large time and temperature window. In this contribution, results on viscous flow, relaxation and crystallization of Zr-Ti-Cu- Ni-Be BMG forming alloys are presented. The data are compared with the kinetics of other metallic and non-metallic liquids. BMG formers are relatively strong liquids with melt viscosities that are about three orders of magnitude larger than in pure metals and other alloys. The strong liquid behavior of these alloys is also reflected by a small entropy of fusion and a weak temperature dependence of the thermodynamic functions upon undercooling. The high viscosity and small driving force for crystallization are major contributing factors to the high glass forming ability and low critical cooling rate. The upper portions of experimental timetemperature- transformation diagrams down to the crystallization nose can be described well using the kinetics deduced from the viscosity data. For lower temperature the viscosity can not describe the crystallization kinetics. The time scale for structural relaxation becomes larger than for diffusive hopping processes. Diffusion stays relatively fast, whereas viscosity and structural relaxation time upon undercooling follow a Vogel-Fulcher-Tammann relation.
Crystallization of Supercooled Zr41Ti14Cu12Ni10B23 Melts During Continuous Heating and Cooling
Authors: Schroers Jan , Masuhr Andreas , Busch Ralf , Johnson William L. 
Published: April 2011

AbstractThe crystallization behavior of the bulk glass forming Zr41Ti14Cu12Ni10Be23 liquid was studied under different heating and cooling rates. Investigations were performed in high purity graphite crucibles since heterogeneous surface nucleation at the container walls does not effect the crystallization of the bulk sample. A rate of about 1 K/s is sufficient to circumvent crystallization of the melt while cooling from the equilibrium melt. In contrast, upon heating a rate of more than 150 K/s is necessary to avoid crystallization of Zr41Ti14Cu12Ni10Be23 samples. The difference between the critical heating and cooling rate is discussed within classical nucleation theory and diffusion limited crystal growth. The calculated difference of the critical heating and cooling rate can be explained by the fact that nuclei formed during cooling and heating are expose to different growth rates.
Atomic Diffusion in Bulk Metallic Glasses
Authors: Geyer Ulrich , Rehmet Achim , Schneider Susanne 
Published: April 2011

AbstractDiffusion experiments in bulk metallic glasses are reviewed. Measurements carried out so far are focused on Zirconium based alloys and cover the amorphous and deeply undercooled liquid states as well as the equilibrium and slightly undercooled melts. Experimental findings are compared with theoretical predictions for atomic transport in glass forming systems.
Bulk Glass-Forming Metallic Alloys: Science and Technology [1998 Mrs Medal Award Lecture, Presented at Symposium Mm]
Authors: Johnson William L. 
Published: April 2011

AbstractThe paper begins with some brief remarks about the history and background of the field of bulk glass-forming metallic alloys. This is followed by a discussion of multicomponent glass-forming alloys and deep eutectics, the chemical constitution of these new alloys, and how they differ from metallic glasses of a decade ago or earlier. The development of bulk glass forming alloys has led to interesting studies of the deeply undercooled liquid alloys, which are made possible by the exceptional stability with respect to crystallization. Recent advances made in this area will be illustrated by several examples. The paper continues with a discussion of some of the physical properties of bulk metallic glasses. Mechanical properties are specifically discussed. Some interesting potential applications of bulk metallic glasses will be mentioned.
High Dynamic Mechanical Strength of Zirconium-Based Bulk Amorphous Alloys
Authors: Zhang Tao , Inoue Akihisa 
Published: April 2011

AbstractA bulk amorphous Zr55Al10Ni5Cu30 alloy prepared by squeeze casting was found to exhibit high mechanical strength values, i.e., uniaxial tensile fracture strength (σt) of 1850 MPa, three-point bending strength (σb) of 3200 MPa, bending fatigue strength (σf) of 1100 MPa, Charpy impact fracture energy (Ef) of 135 kJ/m2 and fracture toughness of 68 MPa√m. The σb, σf and Ef are about two times higher than those for the corresponding bulk amorphous alloys prepared by unidirectional solidification and powder consolidation techniques, though the σt of the squeeze cast sample is higher by about 15 % than those for the other samples. The remarkable increases in the σb, σf and EF are presumably due to the introduction of high compressive residual stress of about 1240 MPa in the outer surface region only for the squeeze cast sample. The finding of the effectiveness of the compressive residual stress on the increase in the mechanical strength under the bending stress mode is important and expected to be widely used as a new strengthening mechanism for bulk amorphous alloys, as is the case for reinforced oxide glasses subjected to strengthening treatment.
Deformation Behavior in La55Al25Ni20 Metallic Glass
Authors: Kawamura Y. , Nakamura T. , Inoue A. 
Published: April 2011

AbstractWe investigated the deformation behavior of the supercooled liquid in a La55Al25Ni20 (at.%) metallic glass ribbon that has a wide supercooled liquid region of 65 K before crystallization. The deformation of the metallic glass was divided into three types, namely, homogeneous deformations with and without a stress overshoot and an inhomogeneous deformation. The supercooled liquid above the glass transition temperature (Tg) exhibited a Newtonian viscosity and superplastic-like behavior during isothermal tensile deformation. The metallic glass was elongated as much as 1000 % at high strain rates ranging from 10−2 s−1 to 10o s−1 without embrittlement. The maximum elongation to failure was in excess of 1800 % at a strain rate of 1.7×10−1 s−1 and at 503 K (Tg+20 K, 0.71Tm) under about 40 MPa.
Synthesis and Properties of Bulk Metallic Glass Matrix Composites
Authors: Choi-Yim Haein , Busch Ralf , Johnson William L. 
Published: April 2011

AbstractBulk metallic glass matrix composites are processed and investigated by X-ray diffraction, DSC, optical microscopy, SEM, microprobe, TEM, and mechanical testing. Ceramics such as SiC, WC, or TiC, and the metals W or Ta are introduced as reinforcements into the metallic melt. The metallic glass matrix remains amorphous after adding up to 30 vol% of particles. The thermal stability of the matrix does not deteriorate after adding the particles. ZrC layers form at the interfaces between the bulk metallic glasses and the WC or SiC particles. Si and W are released into the matrix in which Si enhanced the glass forming ability. The composites are tested in compression and tension experiments. Compressive strain to failure increases by over 300% compared to the unreinforced Zr57Nb5Al10Cu15.4Ni12.6 and the energy to break of the tensile samples increases by over 50% adding 15 vol. % W.
Calculation of Mechanical, Thermodynamic and Transport Properties of Metallic Glass Formers
Authors: Çağin Tahir , Kimura Yoshitaka , Qi Yue , Li Hao , Ikeda Hideyuki , Johnsonb William L. , Goddard William A. 
Published: April 2011

AbstractRecently, we have parametrized Sutton-Chen type empirical many body force fields for FCC transition metals to study the thermodynamic, mechanical, transport and phase behavior of metals and their alloys. We have utilized these potentials in lattice dynamics calculations and molecular dynamics simulations to describe the structure, thermodynamic, mechanical and transport properties of pure metals and binary alloys in solid, liquid and glass phases. Here, we will describe these applications: mechanical properties of binary alloys (Pt - Rh) and viscosity of a binary alloy, (Au - Cu), as a function of composition, temperature, and shear rate, crystal-liquid, liquid-crystal phase transformation in (Ni - Cu), liquid to glass transformation in a model glass former, (Ag - Cu).
Tribological Characteristics of Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 Bulk Metallic Glass
Authors: Fu Xi-Yong , Rigney D. A. 
Published: April 2011

AbstractThe sliding characteristics of Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 bulk metallic glass have been examined in vacuum and in air using a pin/disk geometry without lubrication. The counterface material was either the same metallic glass (self-mated) or 52100 steel. Normal load was 0.1–1 kgf. The test system was equipped for continuous measurement of friction force. In addition, a Kelvin probe allowed continuous monitoring of changes in the structure and chemistry of the disk surface. Post-test characterization included optical and electron microscopy, X-ray diffraction and EDS of worn surfaces and debris. Friction coefficients in both vacuum and air were typical of those expected for ductile materials, with values ranging from 0.4 to 0.9 (higher values with lower load). Wear rates and average debris size increased with load. Wear rates were larger in air than in vacuum. Wear surface appearance and chemical composition were influenced by plastic deformation, material transfer and environmental interactions. After tests in air, the wear tracks and debris had a granular appearance and oxygen concentrations were high. Changes in the Kelvin probe signal correlated well with visual observations and with concentrations of oxygen detected by EDS.
Free Volume Changes in Bulk Amorphous Alloys During Structural Relaxation and in the Supercooled Liquid State
Authors: Nagel C. , Rätzke K. , Schmidtke E. , Faupel F. 
Published: April 2011

AbstractVolume changes in Zr46.7Ti8.3Cu7.5Ni10Be27.5 and Zr 65Al7.5Ni10Cu17.5 bulk metallic glasses have been observed by positron annihilation and density measurements. At low cooling rates excess volume of the order of 0.1 % is quenched in both glasses. Isothermal relaxation kinetics below the glass transition temperature obey a Kohlrausch law with exponents of β≈(0.3 ± 0.1). Structural relaxation is not accompanied by embrittlement, as indicated by simple mechanical tests. The outer surface plays a crucial role in annealing of excess volume, which can be restored by annealing above Tg. The observed free volume changes are at variance with the behavior of a perfectly strong glass. The temperature dependence of the positron lifetime is discussed in terms of thermal detrapping from shallow traps.
High-Temperature Stability of Amorphous Al2O3 Deposited on Si and CeO2-stabilized ZrO2 by Metalorganic Chemical Vapor deposition
Authors: Meyer J. D. , Lee W. Y. 
Published: April 2011

AbstractAluminum acetylacetonate and water vapor were used to deposit an amorphous A1203 seal coating on Si and CeO2-stabilized ZrO2 (CSZ) produced by air plasma spray. The A1203 coating prepared at ∼500°C was ∼2.5μm thick, uniform, and non-porous. The crystallization and adhesion characteristics of the A1203 coating were examined by thermally annealing the A12 03- coated Si and CSZ substrates in air. The amorphous coating crystallized to metastable A1203 phases within 20 hours at temperatures as low as 700°C. The coating on Si spalled upon annealing whereas the coating on CSZ did not spall, but microcracked extensively due to the significant volume shrinkage associated with crystallization.
SiO2 Film Coatings with VUV Excimer Lamp CVD
Authors: Kurosawa K. , Takezoe N. , Yanagida H. , Nomura R. , Yokotani A. 
Published: April 2011

AbstractSilica film coatings were demonstrated using photo-chemical vapor deposition with a 172-nm Xe excimer lamp. Tetraethoxyorthosilicate (TEOS) molecules were successfully dissociated into SiO2+2C2H5-OH+;(residual C and H) with the 7.2-eV photons. The films were deposited onto a quartz or Al203 single crystal substrate with the deposition rate of 1 nm/min. The films were uniform and smooth enough for optical applications.
Metal / Silicon Multilayers Produced by Low-Temperature MOCVD
Authors: Hamelmann F. , Haindl G. , Klipp A. , Majkova E. , Kleineberg U. , Jutzi P. , Heinzmann U. 
Published: April 2011

AbstractW/Si and Mo/Si multilayers with 20 periods (doublelayer spacing d = 24nm) were deposited on silicon substrates using (remote-) plasma-enhanced MOCVD. The substrate temperature was below 200°C, which is necessary to avoid interdiffusion of the layers. The layer thickness and growth was controlled by an in situ soft x-ray reflectivity measurement. The characterisation of the multilayers showed an excellent growth of the silicon layers, while the metal layers are rough with embedded crystallites.
Polymer Multi-Layer Processing of Thin Film Materials
Authors: Miller T. A. , Mikhael M. G. , Ellwanger R. , Boufelfel A. , Booth D. , Yializis A. 
Published: April 2011

AbstractPolymer Multi-Layer (PML) processing is a high speed industrial scale process for depositing thin polymer films. Moving substrates of arbitrary width can have one micron (typ.) polymer films deposited at speeds measured in hundreds of meters per minute. A wide variety of chemical functionality available in the precursor materials allows a variety of chemical, electrical, and optical applications. The polymer characteristics can be further augmented by subsequent deposition of inorganic materials. Recent advances with dielectric, electrolytic, photonic, barrier, chemical affinity, energetic, and piezoelectric thin film polymer materials are discussed.
Structure and Strength of Rapidly Quenched Cu-Al2O3 Composites
Authors: Il'Insky A. I. , Terletsky A. S. , Zozulya E. W. 
Published: April 2011

AbstractMicrostructure of dispersion hardened composites (DC) Cu-Al2O3 prepared by simultaneous vacuum vapor condensation of Cu and A12O3 was studied by X-ray diffractometry and transmission electron microscopy methods. After high temperature annealing at 900°C for 2 hours the composites retain the submicrocrystalline structure and high level of strength -0.9 GPa. It has been found that strain hardening of vacuum deposited Cu-A12O3 composites takes place in three stages that is not typical for well-known composites of metallurgical origin.