bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interface Synthesis By UHV Deposition/Diffusion Bonding
Authors: Kim M. J. , Cox M. J. , Xu J. 
Published: April 2011

ABSTRACTAn ultra high vacuum (UHV) deposition/bonding system has been constructed that can produce planar interfaces from a wide array of materials. The interfaces in this system can be synthesized in-situ by UHV diffusion bonding of two substrates with or without various interfacial layers. Substrate surfaces can be heat treated, sputter cleaned and characterized in-situ prior to deposition and/or bonding. Interfacial layers can be deposited by e-beam evaporation and/or sputter deposition in any layered or alloyed combination. After deposition, the two substrates are bonded in UHV, by the application of heat and pressure.This synthesis procedure permits systematic variation and control of interface morphology and chemistry. Integrity of the bonded interface as well as the microstructure and chemistry are examined by cross-sectional analytical transmission electron microscopy. In this study, stainless steel and single and polycrystalline alumina were used as substrate materials to produce interfaces with and without Ti and Cu interlayers.
Hydrogenation and Magnetic Properties of Pd/Co Multilayers
Authors: Suzuki A. , Kyuno K. , Akiba E. , Manago T. , Miyajima H. , Yamamoto R. 
Published: April 2011

ABSTRACTThe magnetic properties of sputtered Pd/Co multilaysers in hydrogen atmospheres were studied. The x-ray diffraction(XRD) patterns in hydrogen atmospheres showed that the lattice expansion of hydrogenated Pd decreased with decreasing thickness of Pd layers, which is reminiscent of nano-crystalline Pd. Perpendicular magnetic anisotropy(PMA) and saturation magnetization were reduced by the hydrogénation. The interface anisotropy energy per unit area, Ks, and volume anisotropy energy per unit volume, Kv are discussed. These results suggest that interface magnetic anisotropy between Pd and Co layers is suppressed by hydrogenation.
Boron Nitride Coatings on Silicon Carbide Whiskers
Authors: Brown Steven , Partch Richard 
Published: April 2011

ABSTRACTBoron nitride thin films have been produced on silicon carbide whiskers (SiCw) by a novel processing method. A polydivinylbenzene (PDVB) coating was formed in situ on the whisker surface which was subsequently thermally degraded creating a highly porous carbon layer. The total available pore volume of the carbon layer/ SiCw system (SiCwC) was varied by controlling the quantity of PDVB adsorbed. Next, anhydrous sodium borate was mixed with the SiCwC, and upon heating, the precursor melted and absorbed into the porous carbon layer followed by nitridation with anhydrous ammonia. Under certain reaction conditions, silicon oxynitride was also produced as a sublayer. The amount of the latter can be controlled by varying the reaction temperature and time. Control over the thickness of the BN film was achieved by varying the amount of the carbonized polymer layer in proportion to the quantity of sodium borate.
Tem Characterization of Highly Oriented Diamond Films on (001) Silicon Synthesized by Bias Enhanced Nucleation Technique
Authors: Jeon Seung-Joon , Chawla Arun Kumar , Baik Young-Joon , Sung Changmo 
Published: April 2011

ABSTRACTHighly oriented diamond films were deposited on a (001) silicon substrate by bias enhanced MPCVD technique. Three-dimensional TEM characterizations were carried out to understand the nucleation and growth mechanism of diamond grains. The surface morphology, defects, and misorientations of diamond films were compared as a function of synthesizing temperatures and thickness of the films. From our experimental results the texture formation mechanism of diamond films is discussed.
Metal Oxide and Metal Carbide Thin Film Coatings on Large Spherical Particles
Authors: Stephenson Richard C. , Partch Richard E. 
Published: April 2011

AbstractSynthesis and characterization of titanium and zirconium oxide and carbide thin films (1–25 μm) on spherical substrates is reported. Hydrolysis of an appropriate metal alkoxide precursor in aqueous acid yields the amorphous metal oxide coating. Thermal treatment can produce the highly crystalline phases of the oxides or, in the presence of a carbon containing reducing gas, the metal carbide. Scanning electron microscopy and x-ray diffraction have been used to study the surface morphology and the crystallographic structure of the coating films. Morphological characteristics strongly depend on the acid species and acid strength used during hydrolysis. The thickness of the film is also governed by control of the acid hydrolysis step.
Interface Characterization and Delamination Mechanism of c-BN Film
Authors: Kim Ig-Hyeon , Sung Changmo , Lee Sang-Ro , Seo Young-Woon 
Published: April 2011

ABSTRACTCubic boron nitride films were prepared by helicon wave plasma CVD process on (100) Si. The growth and delamination mechanism of c-BN film was investigated with FT-IR spectroscopy and transmission electron microscopy. The film deposited under the intense impact of energetic ions is usually delaminated from the substrate after deposition. It is found that moisture in the air, surface roughness of the film and substrate, as well as severe compressive stresses in the film are the primary contributors to film delamination. An aqueous oxidation was verified by EDXS analysis, which generate local stress by volume expansion at the crack region in the c-BN layer. From the experimental results and ??? observation a model for the delamination mechanism of c-BN film is suggested. Based on the delamination mechanism, several kinds of remedies such as post annealing and post N2plasma treatment were carried out for improving the adhesion.
Residual Stress Effects on the Fracture of Tantalum Nitride Films
Authors: Moody N. R. , Hwang R. Q. , Angelo J. E. , Venkataraman S. , Gerberich W. W. 
Published: April 2011

ABSTRACTIn this study, continuous microscratch testing was used to determine the effects of compressive residual stresses on the fracture of thin tantalum nitride films. The films were sputter deposited at room temperature onto single crystal sapphire substrates to a thickness of 600 nm. Some films were left in the as-deposited condition while the remaining films were vacuum annealed at 300°C. The only discernible change in structure was a surface rearrangement of atoms into parallel arrays of striations on the vacuum annealed samples revealing a high compressive residual stress in the films. These stresses had a strong effect on fracture as shown by the as-deposited films which buckled readily during scratch tests forming uniform-width and circular blisters while the vacuum annealed films exhibited a much lower susceptibility to fracture. Application of mechanics-based models for film buckling defined the levels of compressive residual stress and their effect on interfacial fracture.
Residual Stresses in Single and Multilayer Composite Diamond Coatings
Authors: Jagannadham K. , Watkims T. R. , Narayan J. 
Published: April 2011

ABSTRACTResidual stresses were measured in different types of diamond coatings deposited onto molybdenum substrates by hot filament chemical vapor deposition. The types of coatings examined include a continuous single layer diamond coating and a continuous multilayer diamond composite coating with an aluminum nitride embedding layer. The stresses were determined by X-ray diffraction and Raman spectroscopy and compared.
Interface Shear Strength and Fracture Behavior of NiAl/Metal Laminates
Authors: Fox M. R. , Pickard S. , Ghosh A. K. 
Published: April 2011

AbstractMechanical response of interfaces between intermetallic matrices and ductile reinforcements is of considerable interest in intermetallic matrix composite design. A new approach has been developed to study crack initiation at a planar bimaterial interface by loading one of the adjoining phases in compression. A primarily Mode II stress state with different degrees of superimposed tensile and compressive loading develops at the interface as predicted by FEM analysis. This test method has been used to study NiAl/Mo and NiAl/Cr interfaces in model laminates.
Interfacial Characterization of Mosi2+ X Sic Composite Thin Films on Molybdenum Substrates
Authors: Govindarajan S. , Moore J. J. , Ohno T. R. , Disam J. 
Published: April 2011

ABSTRACTA novel coating architecture is being examined for enhancing the high temperature, oxidation resistance of molybdenum. The coating incorporates a thin, composite film of MoSi2+1.96 mole fraction SiC in order to match the coefficients of thermal expansion between the molybdenum substrate and the coating. Since the as-deposited composite film is amorphous in nature, a diffusion anneal treatment is carried out at 1000°C to achieve crystallization of the film. In this paper, a detailed examination of the Mo-MoSi2+1.96 SiC interface will be presented. The microstructural features of the composite films will be discussed based on electron microscopy, auger electron spectroscopy (AES), and X-ray diffraction analysis. Finally, a novel diffusion barrier layer for minimizing silicon and carbon diffusion from the coating to the substrate will be discussed.
Active Stiffening of Composite Materials by Embedded Shape-Memory-Alloy Fibres
Authors: Bidaux J.-E. , Månson J.-A. E. , Gotthardt R. 
Published: April 2011

ABSTRACTThe use of shape-memory-alloy (SMA) fibres to actively changethe stiffness of a composite beam is investigated on a model system composed of an epoxy matrix with a series of embedded pre-strained NiTi fibres. Stiffness changes are detected through shifts in the natural vibration frequency of the beam. When electrically heated, the pre-strained NiTi fibres undergo a phase transformation. Since the shape recovery associated with the transformation is restrained by the constraints of both the matrix and the clamping device, a force is generated. This force leads to an increase in the natural vibration frequency of the composite beam. Depending on the degree of fibre pre-strain, either ordinary martensite, R-phase or a mixture of the two can be stress-induced. It is found that the R-phase gives rise to the largest change in vibration frequency for a given temperature increase and the most reversible behaviour. Its low transformation strain is also more favourable for fibre-matrix adhesion. The effect of stress relaxation in the polymer matrix on the composite response is discussed.
Mechanical Properties of NiTi-TiC Shape-Memory Composites
Authors: Dunand D. C. , Fukami-Ushiro K. L. , Mari D. , Roberts J. A. , Bourke M. A. 
Published: April 2011

ABSTRACTThis paper reviews recent work on the mechanical behavior of martensitic NiTi composites reinforced with 10–20 vol.% TiC particulates. The behavior of the composites is compared to that of unreinforced NiTi, so as to elucidate the effect of mismatch due to matrix transformation, thermal expansion, twinning or slip, in the presence of purely elastic particles. The twinning and subsequent thermal recovery of deformed composites, measured both macroscopically (by compressive testing and by dilatometry) and microscopically (by neutron diffraction), are summarized.
A Study of Ta2O5 for use as High Temperature Piezoelectric Sensors
Authors: Jooste B. R. , Viljoen H. J. 
Published: April 2011

ABSTRACTAcoustic sensors which can function at high temperatures have important potential uses. In this work we report on the deposition, characterization and qualitative assessment of piezoelectric behaviour of orthorhombic Ta2O5• It is shown that orthorhombic Ta2O5 belongs to the class 2mm. XRD analysis of films annealed for 1 min., 10 min. and 1 hr at 800°C and 900°C reveal the formation of (0 0 1), (1 10 0) and (1 11 0) orientations at 800 °C, but the (1 10 0) increases at the expense of the other two as the annealing period is extended. At 900°C the dominant orientations are (1 10 0) and (2 9 0). The piezoelectric effect is significantly stronger after annealing and the stronger piezoelectric effect does not correlate with the presence of (1 10 0) and (2 9 0) so much as with the absence of (0 0 1) and (1 11 0).
Laser Irradiation Effect on Saw Properties of Layered Structure of Oxide/Piezoelectric Substrate
Authors: Ichikawa Yo , Kitagawa Masatoshi , Setsune Kentaro , Kawashima Syun-ichiro 
Published: April 2011

ABSTRACTUsing surface acoustic wave (SAW) propagating in the layered structure of oxide/piezoelectric substrate, a responsibility of the oxide thin films for the laser irradiation has been investigated. Amorphous Ti-O, Si-O and Si-X-O, where X is other metal elements, films were formed on the surface of the SAW device composed of quartz or LiTaO3 substrate and several hundred Al electrode fingers for oscillating and detecting the SAW. A KrF excimer laser with 248nm in wavelength was used for the irradiation. The center frequency of the SAW devices was immediately decreased by the irradiation of the laser pulses. Although the response to the irradiation was reversible for lower laser energy, the change of the center frequency was irreversible for the laser energy density higher than 20mJ/cm2. It is considered that the response appeared in the frequency shift is generated by a change of an elastic stiffness of the films lowered by an absorption of the laser energy.
High Sensitive Strain Microsensor based on Dielectric Matrix with Metal Nanoparticles
Authors: Konovalov I. A. , Fedorovich R. D. , Nepijko S. A. , Viduta L. V. 
Published: April 2011

ABSTRACTA dielectric matrix, containing metal nanoparticles with interparticle spacings of 1–2 nm, is a system with tunnel mechanism of electrical conductivity. Its electrical resistance is very sensitive to deforming of matrix because it leads to changes in spaces between particles and as a result the potential barrier transperancy is varied.Different metals (Mo, Cr, Ta, Au, Pt, Bi, Al) and their films morphology structure were studied in order to get high sensitive strain sensors. Metal nanoparticles were deposited on elastic dielectric substrates. Strain coefficients were measured for a wide range of strains and temperatures. Variation of matrix structure gives possibilities to produce strain sensors with high electrical resistance and weak temperature dependence. The matrix with Au nanoparticles was found to have maximum strain coefficient (>100). These sensors can be manufactured in the miniature scale (sensitive area around 1 micron or less).
The Influence of Hafnium Content, Cold Work, and Heat Treatment on the R-Phase Transformation of Niti Based Shape Memory Alloys
Authors: Zhang Chen , Thoma Paul E. , Zee Ralph H. 
Published: April 2011

ABSTRACTThe R-phase transformation of a Ti-rich NiTi shape memory alloy (SMA) and two ternary SMAs having the compositions Ni49Ti51-XHfx with lat% and 3at% Hf, has been investigated. The influence of cold work (CW) and heat treatment (HT) on the R-phase transformation is analyzed thermally using Differential Scanning Calorimetry (DSC). Results show that the R-phase transformation depends on the SMA composition as well as the CW and HT conditions in a complex manner. For example, the formation of R-phase upon cooling from austenite (A) is increasingly suppressed with the substitution of Hf for Ti. For the ternary SMA with 3at% Hf, the A→R and R→A transformations are observed only at relatively large amounts of CW (above approximately 40%) and at a high HT temperature (450°C). DSC results also show that for the Ti-rich NiTi and the ternary SMA containing lat% Hf, the A→R and R→A transformation temperatures (TTs) are insensitive to cold work at a HT temperature of 450°C. However, at a lower HT temperature of 350°C, the TTs are found to decrease with increasing CW. For a given CW, the A→R and R→A transformations decrease with decreasing HT temperature and the effect is greatest at high CW (>50%) conditions. An effort is made to identify the factors responsible for the observed behavior in the R-phase transformation.
Smart Piezoelectric PZT Microcantilevers with Inherent Sensing and Actuating Abilities for AFM and LFM
Authors: Lee C. , Itoh T. , Chu J. , Ohashi T. , Maeda R. , Schroth A. , Suga T. 
Published: April 2011

ABSTRACTNovel designs of the force sensing components for an atomic force microscope (AFM) and lateral force microscope (LFM) have been proposed in this study. By using PZT thin layers, a smart structure that can perform force sensing and feedback actuation at the same time is applied to the AFM. Clear images can be derived by an AFM equipped with this smart structure. A structure of two parallel PZT bars integrated on a SiO2 free standing cantilever has shown potential for operation in an LFM, because a difference in the piezoelectric charge outputs from these two beams will be induced by frictional force when the cantilever end quasi-staticly contacts with the sample surface in dynamic scanning across the surface.
Phase Transformations and Crystallography of Twins in Martensite in Ti-Pd Alloys
Authors: Nishida M. , Morizono Y. , Kijima H. , Ikeya A. , Iwashita H. , Hiraga K. 
Published: April 2011

ABSTRACTPhase transformations and crystallography of twins in near-equiatomic Ti-Pd alloys have been studied. In the first half we have found that the transformation temperature decreases with decreasing the Pd contents and the successive transformations take place in the Ti-rich alloys. While the transformation temperature is nearly constant with the composition and a single transformation takes place in the equiatomic and Pd-rich alloys. The solubility limit of TiPd compound in Ti-rich side is extended to about 55 at%Ti at 900°C and abruptly decreased with decreasing temperature. In the latter half we have found three twinning modes, i.e., {111} Type I, <121> Type II and {101} compound twins, in the martensite. The {111} Type I and <121> Type II twinnings which are conjugate to each other coexist in the same variant. The {111} Type I twins are dominantly observed and the <121> Type II twins are less frequently observed. The former twinning is considered to be a lattice invariant shear. There is no martensite variant consisting wholly of the <121> Type II twins throughout the present observation. The <121> Type II twinning is considered to be a deformation twin due to the elastic interaction during the transformation. The {101} compound twinning is also considered to be a deformation twin, since the twin has an isolated fashion in the martensite variant. The boundary structure of the above three twinning modes was also discussed on the basis of lattice image.
Shape Memory Effect and Pseudoelasticity in Ti-40%Ni-10%Cu (At.%) Single Crystals
Authors: Chumlyakov Yu.I. , Kireeva I. V. , Zuev Yu.I. , Lyisyuk A. G. 
Published: April 2011

ABSTRACTThe dependence of shape memory effect (SME) and pseudoelasticity (PE) on crystal orientation and on sign of applied stresses (tension/compression) has been investigated on Ti-40%Ni-10%Cu (at.%) single crystals. It have been shown that both SME and PE depend on an orientation and an applied stress sign. Asymmetry effects were found at deformation in high-temperature B2 phase and in the range of stress-induced martensite transformations.
Nonthermoelastic and Thermoelastic Martensitic Transformation Behavior Characterized by Acoustic Emission in An Fe-Pt Alloy
Authors: Ohtsuka H. , Takashima K. , Olson G. B. 
Published: April 2011

ABSTRACTAcoustic emission (AE) signals generated during the martensitic transformation in an Fe-24at%Pt alloy with various ordering treatments have been measured, and the AE parameters have been correlated with phase transformation events. AE events are generated during cooling of specimens, which is the first detection of the AE events associated with the martensitic transformation in Fe-Pt alloys. In all specimens, AE events were observed at higher temperature than the Ms temperatures determined by electrical resistivity measurement. AE events started to increase abruptly for the weakly ordered specimen with decreasing temperature. In contrast, AE events increased gradually for the highly ordered specimen with decreasing temperature. This is consistent with the nature of the transformation behavior in this alloy. The critical defect size of weakly ordered and highly ordered specimens were calculated using Ms temperature determined by AE technique. Results obtained in this investigation strongly suggests that the AE technique is useful for analysis of transformation kinetics in this alloy.
The Effect of Reverse Transformation on Recovery • Recrystallization Process in Ti-Pd-Ni High Temperature Shape Memory Alloys
Authors: Xu Ya , Otsuka Kazuhiro , Ueki Tatsuhiko , Mitose Kengo 
Published: April 2011

ABSTRACTThe effect of martensitic reverse transformation on recovery • recrystallization process in cold rolled Ti-Pd-Ni high temperature shape memory alloys has been investigated systematically by flash heating treatment, micro-Vickers hardness test, differential scanning calorimetry and transmission electron microscopy. It was found that the temperatures of softening in hardness after flash heating treatments agree well with the reverse transformation temperatures in the present alloys, and most of the softening occurs within 60 seconds when annealing temperature is raised to above the reverse transformation temperature. We conclude that the recovery • recrystallization process is controlled by the reverse transformation. The reasons are considered based on the large difference in atomic diffusion rate in the parent phase and in the martensite.
Microstructures and Mechanical Properties of 6061 Al Matrix Smart Composite Containing TiNi Shape Memory Fiber
Authors: Lee J. H. , Hamada K. , Miziuuchia K. , Taya M. , Inoue K. 
Published: April 2011

ABSTRACT6061 Al-matrix composite with TiNi shape memory fiber as reinforcement has been fabricated by vacuum hot pressing to investigate the microstructure and mechanical properties. The yield stress of this composite increases with increasing amount of prestrain, and it also depends on the volume fraction of fiber and heat treatment. The smartness of the composite is given due to the shape memory effect of the TiNi fiber which generates compressive residual stresses in the matrix material when heated after being prestrained. Microstructual observations have revealed that interfacial reactions occur between the matrix and fiber, creating two intermetallic layers. The flow strength of the composite at elevated temperatures is significantly higher than that of the matrix alloy without TiNi fiber.
Fabrication of Piezoelectric Sensors for Biomedical Applications
Authors: Hussajn Iqbal , Kumar Ashok , Mangiaracina A. , Perlaky S. C. , Mccombs S. C. , Zhong F. , Weimer J. J. , Sanderson L. 
Published: April 2011

ABSTRACTBiosensors are a special class of chemical sensors that take advantage of the high selectivity and sensitivity of biologically active material. We are currently investigating the characteristics of various deposited electrode coatings (Au and Pt) on 10 MHz quartz crystals using the sputtering method. We are also investigating the effect of magnetic behavior (by intermixing Fe and Ni with electrodes) on the binding nature of antigen with the substrate. A change in mass occurs due to the binding of antigens and antibodies on the surface of the thin film coating. The frequency change as a result of a change in mass makes it possible to use these crystals as biological sensor devices. This paper describes the construction of antibody-based piezoelectric crystals capable of detecting mycobacterial antigens in diluted cultures of attenuated M. tuberculosis. The microstructural features of these crystals have been studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The crystallographic properties have been characterized using the X-ray diffraction (XRD) method. The long term objective of this research is to develop a rapid quantitative method of analysis for the diagnosis of tuberculosis (TB) and other infections caused by mycobacteria, using biosensor technology.