bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binder System Containing Polycarbosilane and Polysiiazane for Injection-Molded Si3N4 Parts
Authors: Su Sophia R. 
Published: March 2011

ABSTRACTPolycarbosilane and polysilazane, precursors of SiC and Si3N4, have been incorporated into the binder system for injection-molded Si3N4-based parts. Property requirements for these precursors as the injection-molding binder are briefly described. The binder removal mechanism is proposed and discussed based on the experimental results. Instead, the gas diffusion effect, rather than fluid wicking, is a key factor. Controlling the thermal decomposition rate of the binder is the key for achieving crack-free dense sintered parts.
Surface Oxidation Kinetics of an a-Si3 N4 and an Amorphous Si3 N4 Powder
Authors: Wang Pu Sen , Malghan S. G. , Hsu S. M. , Wittberg T. N. 
Published: March 2011

ABSTRACTSurface oxidation kinetics of an a-Si3 N4 submicron size and an amorphous nano-size powder have been studied using x-ray photoelectron spectroscopy (XPS) and Bremsstrahlung-excited Auger electron spectroscopy (AES). The samples were oxidized by heating in air at temperatures between 850°C and 1000°C. The oxide thickness for each heating time and temperature was determined both from the relative 0 Is and N Is XPS peak intensities and from the Si02 and Si3 N4 Si KLL peak intensities. In each case, there was a good agreement between the oxide thickness value calculated from the XPS data and that obtained from the AES data. At these temperatures, oxidation followed a linear rate law. Activation energies of 15±1 kcal/mole and 27±1 kcal/mole were measured for the a-powder and the amorphous powder, respectively.
Novel Silicon Nitride Microstructures Through Processing of Phase Separated Polysilazane Gels
Authors: Lindquist David A. , Haggerty John S. , Rhine Wendell E. , Seyferth Dietmar 
Published: March 2011

ABSTRACTTo date, processes used to synthesize to silicon nitride and silicon carbide ceramics from polysilazane preceramic polymers have focused on techniques which seek fully dense monoliths or matrices. An alternative approach, phase separation of polysilazane solutions using appropriate gelation agents, yields infusible preceramic monoliths having controlled two-phase microstructures. Subsequent removal of the solvent phase by supercritical fluid exchange leads to aerogels with defined pore structures. Controlled pore structures were explored as a means of providing diffusional pathways for reactant and product gases during pyrolysis. Resulting changes in the gel microstructure were followed by scanning electron microscopy and surface analysis by nitrogen desorption methods. It was found that micropores present in the unpyrolyzed gels are absent after pyrolysis, but that larger pore structures are maintained.
High Energy Ion Induced Decomposition and Diffusion in Thin Polymer Films
Authors: Venkatesan T. , Edelson D. , Brown W. L. 
Published: March 2011

ABSTRACTElectronic excitation in thin polymer films by MeV ion beams and on-line transient mass spectroscopy together provide a new opportunity for measuring the diffusion of molecules in polymers even when the diffusion coefficients are <∼ 10−10 cm2 s−1.With a quadrupole mass spectrometer, we have obtained transients of several molecular species from a variety of polymers bombarded by 2 MeV helium and argon ions.We have measured, for example, transient emission of D2, CO, CO 2, CD3OD, etc., from deuterated Poly(methyl methacrylate), PMMA.The beam fluences required for the measurements are sufficiently small that they cause minor perturbation in the structure of the film. The exciting ion pulse is typically 15 seconds wide with fast (<msec) rise and fall times. However, the emission signal of m−46 (COOD), for example, shows a slow build-up with a gradual fall after the beam is turned off with a tail lasting several seconds. The experimental data for the above molecule has been fitted to a one-dimensional diffusion model and the diffusion coefficient deduced from three different film thicknesses is ∼8−±2×10−11 cm2S−1 Since very thin films can be used in these experiments, still smaller D values are measurable. The sample requirements are simple and even the presence of pinholes will not affect the measurements significantly. Techniques that completely avoid any possible effects of ion damage tracks and an example where chemical reaction is the rate limiting step will be discussed.
Electron Energy Loss Spectroscopy of Polycrystalline and Ion Irradiated Ni-Al Alloys
Authors: Grunest L.A. , Barbour J.C. , Hung L.S. , Mayer J.W. , Ritsko J.J. 
Published: March 2011

ABSTRACTIon beam modifications to thin film, polycrystalline Ni-Al alloys have been investigated using high resolution (0.1 eV FWHM) transmission electron energy loss spectroscopy (EELS). The ion induced modification of Ni3 AI,NiAI, Ni2Al3, and NiAl3 as measured by EELS, are compared to concurrent electron microscope diffraction analyses. The EELS coresub level spectra corroborate the NiAI3 to amorphous phase transition observed by diffraction, while the EELS valence spectra provide a signature for the Ni2Al3 to NiAl phase transformation. These results reflect the changes in the electronic states caused by changes in the crystal structure. In addition, perturbations to the electronic states are measured even when no change appears in the diffraction pattern (irradiated NiAl). Thus, high resolution EELS is shown to be a sensitive analytical technique for studying ion irradiated materials.
A General Treatment of Antiphase Domain Formation and Identification at Polar-Nonpolar Semiconductor Interfaces.
Authors: Pond R.C. , Gowers J.P. , Holt D.B. , Joyce B.A. , Neave J.H. , Larsen P.K. 
Published: March 2011

ABSTRACTObservations of antiphase disorder obtained using a new technique of transmission electron microscopy, in (100) epitaxial layers of GaAs:Ge produced by MBE are presented. The crystallographic origin of this type of disorder is analysed using a recently developed approach. It is shown that antiphase disorder can exist in epitaxial layers where the substrate orientation is of the form {hko}this is consistent with experimental observations that disorder is observed on (100) and (110) substrates, but not on (111) or (211), for example. Antiphase boundaries in {hko} specimens are shown to separate interfacial domains which are energetically degenerate and related by symmetry operations.
Metal Induced Grain Growth in Germanium and Silicon Thin Films.
Authors: Grovenor C.R.M. , Smith D.A. 
Published: March 2011

ABSTRACTRapid grain growth has been induced in semiconductor films at relatively low temperatures by allowing contact with metals or metal/semiconductor eutectic melts. Mechanisms by which such enhanced grain growth can occur are discussed, and Diffusion Induced Boundary Migration has been shown to be a plausible explanation for the experimental observations from the Sn/Ge, Al/Ge and Au/Ge systems. Interface migration driven by the decrease in free energy during phase transformations however provides a better explanation of the large Si grains produced on heating the Au/Si samples.
Chemical Reaction at the Ni/Inp (110) and Ni/GaAs (110) Interfaces
Authors: Kendelewicz T. , Petro W. G. , Williams M. D. , Pan S. H. , Lindau I. , Spicer W. E. 
Published: March 2011

ABSTRACTThe chemical reaction at the Ni/InP (110) and Ni/GaAs (110) interfaces produced by sequential deposition of thin Ni overlayers onto cleaved semiconductor surfaces has been investigated with valence band (VB) and core level photoemission and Auger spectroscopies using synchrotron radiation as the excitation source. By monitoring changes in the VB, P 2p, In 4d, Ga 3d, As 3d, and Ni 3p photoemission spectra and the lineshape of the P LVV Auger transition during the initial stage of Schottky barrier formation, we found that for both interfaces the first few Å of Ni react strongly with the surface resulting in the formation of a nickel phosphide or nickel arsenide. At the same time, segregation of metallic In or Ga is observed.
Photoemission Studies Of The CU-GaAs(ll0) Interface Formation
Authors: Pan S. H. , Kendelewicz T. , Petru W. G. , Williams M. D. , Lindau I. , Spicer W. E. 
Published: March 2011

ABSTRACTThe cu-GaAS(ll0) interface formation nas been Studied with soft x-ray Photoemssion spectroscopy (SXPS) for Cu overlayers deposited at room temperature. Tne evolution of the tia 3a and As 3a spectra snow that strong interactions occur between Cu and the substrate during the formation of the Cu-GaAs interface. A cnemically smifted Ga 3d peak at 0.8 eV lower binging energy and strong moaification of the As 3d lineshape has been found. Detailed analysis nas shown that the dissociated As is preterentially segregated on the metal layer, but Ga remains mainly in the interfacial reion for trick Cu coverages (30 - 60 Å). Using a deconvolution tecnniqie we nave found that the final stabilized position of the interface Fermi level lies at about 0.9 eV below the conduction band minimum.
Residual Stresses in Co-Sputtered Films of Ta and Si on Substrates of Silicon and Oxide.
Authors: Goldsmith C. C. , Campbell D. R. , Mader S. 
Published: March 2011

ABSTRACTWe have measured the stresses in TaSi. films both as a function of annealing temperature and of composition of the as-deposited films. Substrates of Si, polysilicon and SiO2 were used. The residual, room temperature stresses in samples annealed at 900°C are noticeably dependent on the initial Si/Ta ratio. This effect appears to to be related to microstructural differences between Si-rich and Ta-rich films. The stresses are largely due to the mismatch of thermal expansion coefficients (TEC) between the silicide and silicon although there is also evidence that samples annealed at lower temperatures (500°C) may have a sizable component of intrinsic stress as well. Despite tensile stresses as high as 1500 MPa, the x-ray topographs of Si wafers with patterned silicide/polysilicon structures show that no substrate dislocations are present after- annealing.
The Reaction between thin Ni and Co Films and their Disilicides
Authors: Cahoon E.C. , Comrie C.M. , Pretorius R. 
Published: March 2011

ABSTRACTRutherford backscattering has been used to study metal/disilicide thin film interactions for Ni and Co. Upon heating, the metal first reacted with the disilicide to form Ni2Si and Co2Si, respectively. After complete consumption of the free metal, the monosilicide phase was found to form at temperatures between 350°C and 550°C. In the case of Co it was found that after all the metal had been converted to CoSi in this way, the reaction stopped. In the Si<>/NiSi2/Ni system, however, all the disilicide converted to NiSi, even though the thickness of the deposited metal was insufficient to account for this. For this to occur, the disilicide had to dissociate into NiSi and Si, with the excess silicon regrown epitaxially on the silicon substrate.The stability of NiSi2 under various boundary conditions was investigated to determine the factors affecting dissociation. Partial dissociation was found to occur when the NiSi2/Ni reaction proceeded on an inert SiO2 substrate. The disilicide was stable, however, in the Si<>/NiSi/NiSi2 structure. Argon sputtering at temperature was found to induce complete dissociation of NiSi2 on single-crystal Si. We believe that the NiSi2 instability is due to the very small heat of formation from the monosilicide. In such a case, the thermodynamic driving forces are small enough that the reaction can be significantly influenced by the presence of kinetic barriers.
The Effect of Beam Species and Anneal History on Silicon Surface Damage Induced by Ion Beam Etching
Authors: Davis R. J. , Singh R. , Fonash S. J. , Caplan P. J. , Poindexter E. H. 
Published: March 2011

ABSTRACTIon beam etching and reactive ion etching have been shown to significantly damage silicon surfaces. In this investigation, ion beam damage is examined as a function of ion beam type (1 keV Ne+, Ar+, and Kr+) and anneal history (temperatures of 500°, 800°, and 1000°C in ambient gases Ar,dN2, and Ar + H2 ). Damage at 1 keV, as characterized by currentvoltage and ESR measurements, appears to be roughly proportional to the inverse of ion size. Relatively long anneals at high temperatures (1 hr. at 800'-1000°C depending upon ambient) are found to be necessary to restore original surface characteristics.
Effect of Low Energy Hydrogen Implants on Damage Caused by Argon Ion Beam Etching
Authors: Climent A. , Wang J.-S. , Fonash S. J. 
Published: March 2011

ABSTRACTThe dry etching technologies reactive ion etching (RIE) and ion beam etching (IBE) have both been shown to cause a damaged layer at silicon surfaces. It has been demonstrated that this damage can be annealed out or, alternatively, it can be passivated with low energy hydrogen implants from a Kaufman ion source. This study further explores the hydrogen passivation approach by focusing on the effect of hydrogen implantation on damage caused by argon ion beam etching. The lighter hydrogen ions are actually shown ta cause more extensive damage than the heavier argon ions. However, by using low-energy hydrogen implants all damage, that present from the Ar and that generated during the hydrogen implant, can be passivated.
Electrostatic Spray Deposition of Antimony Doped Tin Oxide on Soda-Lime Glass
Authors: Fabian D.J. , Colbow K. , Clayman B.P. , Mackintosh A. , Manning G. , Morrison S.R. 
Published: March 2011

ABSTRACTA technique for electrostatic spray deposition (ESD) of thin films onto a conducting substrate is described. The method, using a 60 kV corona has been tested for the preparation of heat-reflecting tin oxide coatings onto window glass by spraying solutions of hydrated tin tetrachloride with 1% antimony trichloride in ethyl acetate.Uniformity of film, growth rate, conductivity, infrared reflectivity and light transmission in the visible are all examined and compare favourably with films produced by normal aerosol spray. Conductivity and infra-red reflectivity increase with the substrate temperature during ESD. This is similar to the observation for antimony-doped tin oxide films prepared on soda-lime glass by CVD; although this temperature dependence does not follow closely that reported for normal spray deposition.
Initial Phase formation at the Interface of Ni, Pd, or Pt and Si
Authors: Nemanich R. J. , Tsai C. C. , Stafford B. L. , Abelson J. R. , Sigmon T. W. 
Published: March 2011

ABSTRACTThe initial phase formation at the interface of the near noble metals (Ni, Pd, and Pt) and Si is studied by Raman spectroscopy and Rutherford ion-backscattering. The results show that a crystalline Pd2Si forms immediately at the interface of Pd and Si while a disordered intermixed phase of composition ∼M2Si forms for Ni and Pt at 150°C. The results are discussed in terms of the disorder due to the kinetic process and the stability of the crystalline phase.
Preparation of Synthetic Quartz Aggregates under Pressure
Authors: Luan F. C. , Paterson M. S. 
Published: March 2011

ABSTRACTIn 1965 Griggs and Blacic [1,2] proposed that there is a “hydrolytic weakening” process in quartz and silicates whereby the breaking of Si-O bonds, involved in the movement of dislocations, is facilitated by the presence of water. This proposal aimed to explain the observed dramatic weakening of quartz crystals when they are exposed to water in tests at high temperature, as well as the observed strong contrast in creep strength between dry natural quartz crystals and rapidly-grown synthetic quartz crystals containing traces of water. Such a “hydrolytic” process may also underlie the observed effects of water in accelerating other phenomena such as self-diffusion of oxygen in quartz, aluminium-silicon ordering in feldspars, slow crack propagation in silicates, and recrystallization in quartz. A review of this field is given in Reference 3.
Effect of Pressure Carbonization in Carbon/Carbon Composite Process (II)
Authors: Okamoto H. , Hosomura T. , Kosaka K. 
Published: March 2011

ABSTRACTWe have found that pressurized carbonization cause the increase of carbon yield and the improvement of micro structure In the case of pitch resin. While the effects of pressurized carbonization on phenolic resin are not obvious.In this study, carbonization and graphitization characteristics of phenolic resin were investigated experimentally. Phenolic resin specimens with and without iron powder addition were carbonized at the temperature of 650 °C under the pressure of atmospheric or 100MPa. Then each of them was heat-treated at the temperature of 1200, 1500 and 1900 °C respectively. Measurement of yield, density, x-ray diffraction and optical observation were carried out in the experiments. It is indicated from those results that pressurized carbonization of phenolic resin makes graphite crystallization progress and this effect is promoted by addition of iron powder.
Densification of Ceramics by Gas Overpressure Sintering
Authors: Gazza G. E. , Katz R. N. 
Published: March 2011

ABSTRACTThe use of various gas pressure sintering (GPS) techniques for densifying ceramics are reviewed for both oxides and non-oxides. Variations of the process are discussed with respect to process parameters selected, process sequence, and microstructural development. Theoretical considerations underlying the technique are presented. GPS and hot isostatic pressing are compared and the advantages and disadvantages of each are briefly discussed.
Study of Glass Ceramic Diffusion During Hot Isostatic Pressing of Encapsulated PZT Ceramics
Authors: Leriche A. , Aleksandrowicz P. , Thierry B. 
Published: March 2011

ABSTRACTThe development of high performance piezoelectric and dielectric ceramics needs a close control of density and microstructure. Hot isostatic pressing technique using glass encapsulation method allows to produce dense and complex shape ceramics with controlled grain size. However, diffusion phenomena occur at glass ceramic interface during HIP treatment.In this study, the glass diffusion into PZT ceramics was examined for different glass types. We noted silicon species diffusion into ceramic and also lead migration into glass resulting from PZT decomposition.HIP carried out with diffusion barrier surrounding ceramic samples allows to prevent such a diffusion.
X-Ray Induced Optical Absorption in Densified Silica Glass in the UV Region
Authors: Kitamura Naoyuki , Toguchi Yutaka , Kondoh Isao , Yamashita Hiroshi 
Published: March 2011

ABSTRACTX-ray induced optical absorption has been studied on silica glasses densified by hot isostatic pressing. Density of the glass increases up to about 1% in proportion to the operating pressure. Two main absorption bands centered at 5.8eV(215nm) and 4.8eV(260nm) are induced both in the densified and undensified glasses under the irradiation of X-rays at room temperature. The 5.8eV band is enhanced with the increase in density for the glass with low-OH content(<˜200ppm), but is decreased slightly for the glass with high-OH content(>˜200ppm). On the other hand, the 4.8eV band decreases with the increase in density irrespective of OH content, and reaches at a constant value above the densification of about 0.5%. It is found that these absorption bands originate in point defects in the glass and that the densification improves the optical durability of the glass against X-rays when hydroxyl impurities are contained in the glass.
Solid Gas Reaction Phase Diagram under High Gas Pressure - HIP Phase Diagram
Authors: Ishizaki Kozo 
Published: March 2011

ABSTRACTTo evaluate which are the stable phases under high gas pressure conditions, a solid-gas reaction phase diagram under high gas pressure (HIP phase diagram) has been proposed by the author. The variables of the diagram are temperature, reactant gas partial pressure and total gas pressure. Up to the present time the diagrams have been constructed using isobaric conditions. In this work, the stable phases for a real HIP process were evaluated assuming an isochoric condition.To understand the effect of the total gas pressure on stability is of primary importance: Two possibilities were considered and evaluated, those are: i) the total gas pressure acts as an independent variable, or ii) it only affects the fugacity values. The results of this work indicate that the total gas pressure acts as an independent variable, and in turn it also affects the fugacity values.
Characterization of Hot Isostatically Pressed Bi–Sr–Ca–Cu–O as a Function of Consolidation Variables
Authors: Goretta K. C. , Miller D. J. , Poeppel R. B. , Nash A. S. 
Published: March 2011

ABSTRACTFully dense, bulk Bi2Sr1.7CaCu2Ox (2212) superconductor pellets were made by hot isostatic pressing in an inert atmosphere. Electron microscopy revealed that rotation and bending of the platelike 2212 grains were responsible for much of the densification. Under processing conditions of 825°C and 105 MPa, dense pellets were obtained in 15 min. Many dislocations, planar faults, and, perhaps, intergrowths of the Bi2Sr2CuOx phase were produced during pressing. The dislocations were largely present in subgrain boundaries when the pressing times were increased to 45–120 min.
Surface Engineering by HIP
Authors: Stephenson David J 
Published: March 2011

ABSTRACTMethods for surface treating and coating components by hot isostatic pressing are presented. It is shown that HIP'ing can improve the properties of conventional coatings and also be used to produce coatings that would be difficult to deposit by other techniques. The concept of using a combined coating and HIP treatment to modify surface properties by, for example, removing surface defects in metals and ceramics, is also discussed.
Next Generation of High Temperature Structural Intermetallic Compounds
Authors: Cells Pedro B. , Ishizaki K. , Kagawa E. , Ishikawa J. 
Published: March 2011

ABSTRACTSilicon compounds with the (Mn5Si3)16H crystal structure in particular, have a high melting point, which is a necessary characteristic of high temperature structural materials. The compounds Si3Zr5 and Si3Ti2Zr3 with that crystal structure and with melting points around 2500 K, were densified by using a hot isostatic process (HIP) in a glass capsule. This crystal structure shows good creep resistance, which might be due to the particularly large silicon interatomic distance. The high melting point and good creep resistance, make these intermetallics good candidates for the next generation of high temperature structural materials.
Atmosphere Control in the HIP Treatment of Ceramics
Authors: Fujikawa Takao , Manabe Yasuo , Miyatake Takayuki 
Published: March 2011

ABSTRACTThis paper describes the concept and the significance of atmosphere control in the HIP treatment of ceramics and reviews some practical methods to create desirable atmospheres during HIP treatment for some nitride and oxide ceramics by citing published experimental data. The authors propose new HIP equipment which enables atmosphere controlled HIP treatment involving a wide range of ceramics and compounds.
Collagenous Biocomposites for the Repair of Soft Tissue Injury
Authors: Christiansen David , Pins George , Wang Ming Che , Dunn Michael G. , Silver Frederick H. 
Published: March 2011

ABSTRACTResults of implantation studies in a variety of animal tissue models demonstrate that the rate of biogradation of a collagen scaffold should parallel the rate of wound healing observed in particular anatomic sites. This rapid degradation maximizes tissue regeneration and minimizes encapsulation of the implant. The following paper reviews the effects of crosslinking on the rate of tissue ingrowth and regeneration. In addition, preliminary mechanical data on newly developed soluble type I collagen fibers is presented as a possible advance in the production of high strength collagen based tissue scaffolds.