bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Laser Texturing on Technical Surfaces
Authors: Gerbig Y. , Dumitru G. , Romano V. , Spassov V. , Haefke H. 
Published: April 2011

ABSTRACTDifferent laser beam techniques were applied to AISI M3 steel samples in order to produce well-defined surface microtextures consisting of pores, which can act as lubricant pockets (reservoir) as well as traps for wear debris. Both effects contribute to improve the tribological performance of textured functional surfaces. The tribological performance of lasertetxures was studied as function of the pore depth and diameter in unidirectional sliding tests under starved lubrication. The lasertetxured surfaces tested under those conditions were produced by a well-established ns laser technique using a Q switched Nd:YAG laser. The topographical microstructures of these laser-induced textures were characterized by optical and scanning electron microscopy as well as replica technique. A significant change in friction behavior as compared to untextured tool surfaces was observed when using microtextured surfaces.In another part of the study, the influence of new-developed fs laser technique of the tool steel was investigated. The fs laser texturing of the steel results in a change of the metallographic structure of the laser-affected zone, which is clearly detectable in cross-section samples. The structure of the material and chemical composition of the laser-affected, pore-near region was analyzed by transmission electron microscopy with combined EDX analysis. It could be shown that the laser-affected zone seems to consist of an amorphous or nanocrystalline material in opposite to the ‘macrocrystalline’ steel substrate. Nanoindentations revealed a two times higher hardness of the laser-affected zone than the steel bulk phase.
Bright plasma nitriding of ferritic steel with several alloying elements
Authors: Kamminga J.-D. , Kwakernaak C. , Janssen G. C. A. M. 
Published: April 2011

ABSTRACTHot work tool steel was plasma nitrided in a PVD apparatus. Phases occurring and nitrogen depth profiles were assessed for the nitrided specimens. In all cases bright nitriding was achieved. Increasing the nitriding time from 15 to 120 min yielded a nitriding depth increasing from about 15 to 35 μm, whereas the nitrogen flux decreased from 8.0 to 5.5 × 10-7 kg s-1m-2. Results from an existing model, predicting nitrogen depth profiles due to plasma nitriding, did not accurately describe the experimental data. Therefore the existing model cannot be used straightforwardly to predict the formation of iron nitrides. The discrepancies of model results and experimental results are discussed in view of the assumptions underlying the model for plasma nitriding.
Micromechanical Properties of He-Implanted Ni
Authors: Knapp J. A. , Follstaedt D. M. , Myers S. M. 
Published: April 2011

ABSTRACTDetailed finite-element modeling of nanoindentation data is used to obtain the micromechanical properties of Ni implanted with ∼5 at.% He to a depth of 600–700 nm. Properties of He-containing metals have implications for studies of radiation damage and for fundamental issues of dislocation pinning. Cross-section TEM shows the implantation produces a highly damaged layer containing a fine dispersion of He bubbles with diameters of ∼1 nm or smaller, with some evidence for interconnection between bubbles. Nanoindentation of the Ni(He) layers gave a fairly hard, stiff response to depths of 100–120 nm, beyond which the layer failed. By modeling the layer as an isotropic, elastic-plastic solid with the Mises yield criterion, the Ni(He) is shown to have a hardness nearly 7 times that of untreated Ni. However, unlike other treatments that we have used to produce very hard Ni-based layers, the Ni(He) layer fails at relatively modest shear stress levels.
Effects of Inclusions and Porosity on the Indentation Response
Authors: Ege E. S. , Shen Y.-L. 
Published: April 2011

ABSTRACTA combined numerical and experimental study was undertaken to investigate the effect of microstructural heterogeneity on indentation response. Finite element analyses were carried out to simulate the stress-strain behavior and the indentation response of two model heterogeneous systems: one with hard particles embedded within a soft matrix and the other with a pore-containing ductile material. For the particle-containing system, the indentation response consistently overestimates the overall strength of the composite. This is largely due to the localized increase in particle concentration directly underneath the indent. For the porous system, the indentation response consistently underestimates the overall strength due to the pore-crushing effect. Experiments on metal-ceramic composites confirmed the non-correspondence between the indentation and stress-strain responses, even when the indent size is much greater than the microstructural feature size. Implications of the present findings in utilizing indentation to quantify surface mechanical properties are discussed.
Surface Modification of Silica with Ultrahighmolecular Weight Polyethylene (UHMWPE)
Authors: Debnath Subir , Ding Jiang , Wunder Stephanie L. , Baran George R. 
Published: April 2011

ABSTRACTUHMWPE (Ultrahighmolecular Weight Polyethylene) was attached to silica using a two step process, in which the first step involves silanating the silica surface with a 0.5–1.2 mole % vinyltrimethoxysilane-ethylene copolymer (PE-silane), and in which the UHMWPE (Mw = 3–6 × 106) is solution coated onto the silanated silica in the second step. Glass beads (3.6 μm diameter) were cleaned using distilled water or refluxed with 5% aqueous Na2S2O8, to remove metallic surface contaminants, were used for UHMWPE attachments. SEM and optical microscopy showed individual particles. TGA (thermogravimetric analysis) studies confirmed the attachments as well as their stability after attachment. The integrity of the coatings was examined by SEM following treatment with HF, which left thin “skins” of polymer remaining. Both washing methodologies for the glass beads provided similar UHMWPE coatings. Bend bars (10) prepared using UHMWPE coated beads show no adverse drop in moduli and strength.
Microstructure Development and the Mechanisms of Lubrication in Magnetron Sputtered HfC-Ag and SiC-Ag Composite Thin Films
Authors: Endrino Jose L. , Nainaparampil Jose J. , Krzanowski James E. 
Published: April 2011

ABSTRACTA soft thin coating on top of a hard substrate is a highly effective way to reduce friction of sliding mechanical components. However, soft coatings often have high wear and short lifetimes, and the restoring of solid lubricants can be remarkably uneconomical. In our recent work, composite TiC-Ag films were successfully deposited by the magnetron-sputtering pulsed laser deposition technique (MSPLD). Secondary electron (SE) images from the wear tracks revealed that silver migrates to the surface and smears along the sliding direction providing low friction, while the carbide phase provides adequate support and storage for the solid lubricant phase, all resulting in lower wear and longer lifetime. One proposed mechanism for lubrication is the friction-induced thermally activated migration of silver to the surface due to the insolubility of the carbide and silver phases which was corroborated by X-ray diffraction (XRD) analysis. The formation of incoherent interfaces between the two phases, observed by transmission electron microscopy (TEM), may influence the adhesive friction behavior of the soft metal. In this study, we investigate the structural properties and vacuum tribological behavior of SiC-Ag and HfC-Ag films.
Effects of Substrate Materials on Nanoindentation Tests of AlN Thin Films
Authors: Miyabe Shuichi , Aono Masami , Kitazawa Nobuaki , Watanabe Yoshihisa 
Published: April 2011

ABSTRACTAluminum nitride (AlN) thin films with different thickness were synthesized by ion-beam assisted deposition on various substrates, Corning 7059 glass, fused silica, Si single crystal, and sapphire, which show the hardness ranging from 7 to 37 GPa. Effects of substrate materials on indentation-hardness of AlN films were studied by using a nanoindentation system equipped with a diamond Berkovich indenter. The maximum force applied to the films was kept at 3 mN. For the films on the Corning 7059 glass substrate, when the normalized penetration depth to the film thickness is 0.98, the film hardness is found to be about 7 GPa, which is close to the hardness of the substrate. While the normalized penetration depth is reduced to 0.11, the film hardness becomes to be about 16 GPa. On the other hand, for the films on the sapphire substrate, when the normalized penetration depth is 0.83, the film hardness is observed to be about 25 GPa, while the normalized penetration depth is reduced to 0.10, the film hardness is found to be about 15 GPa. These results reveal that when the normalized penetration depth to the film thickness is about 0.1, the hardness of the AlN film can be evaluated to be about 15 GPa without being affected by substrate materials.
Development of In-Situ Surface Observation System with an Atomic Resolution under Tensile Stress by Atomic Force Microscope
Authors: Matsumuro Akihito , Kayukawa Kimiharu , Fujimoto Youhei , Ando Taeko , Sato Kazuo 
Published: April 2011

ABSTRACTA new in-situ surface observation system under tensile stress with an atomic resolution has been developed for the purpose of the explanation of the deformation of the surface and the crack growth mechanism for thin films in the micro- and nano-mechanical systems. The mechanical properties such as Young's modulus can be determined at the same time. This observation system consists of the on-chip tensile testing system and a commercialized atomic force microscope (AFM). The on-chip testing system is characterized by a static loading mechanism with a flat spring and a test chip of single-crystal silicon of 15×15×0.5 mm. Particular attention has been paid to the suppression of the vibration which effects on images of the surface with an atomic resolution. Atomic images of the surface of mica can be observed under various tensile strains till the occurrence of the fracture. The growth of the cracks and Young's modulus for TiN thin film deposited on silicon (100) specimen can be also clarified.
Failure Mechanism Researches of Material Surface and Interface in Micro-Scratch Test
Authors: Wei Yueguang , Zhao Manhong , Tang Shan 
Published: April 2011

ABSTRACTIn the present research, the adhesion properties and failure mechanisms for a ductile thin film on a silicon substrate (Ni/Si) are studied experimentally, and are simulated theoretically. In the experimental research, the relations of the horizontal driving force, vertical displacement and the frictional coefficients with horizontal displacement are measured. Furthermore, the variation of the total energy release rate and the frictional coefficient between contact surfaces are measured through obtaining a frictional effect law. The law displays that the frictional influences on the energy release rate of the total system weakly depend on the thin film thickness. This conclusion leads to that the frictional effect can be eliminated in the toughness ratio relation approximately. So that one can directly obtain the interfacial adhesion toughness from measurements in the micro-scratching test. In addition, the micro-scratching process for the ductile thin film/brittle substrate systems is simulated using the double cohesive zone model. Prediction results of the energy release rate are obtained, and are compared with the experimental results obtained in the present research.
Metrology Issues in Cu-Low-K Chemical Mechanical Planarization
Authors: Zantye Parshuram B. , Sikder Arun K. , Thagella Swetha , Gulati Nivedita , Kumar Ashok 
Published: April 2011

ABSTRACTUltra low-k materials used in Cu damascene process are inherently soft and weak in nature; hence the evaluation of tribological properties of these materials is an issue of paramount importance in the field of semiconductor fabrication. Chemical Mechanical Polishing (CMP) of these films is a major challenge due to their reduced modulus and cohesive strength. The objective of this research is to develop a strong understanding of the tribological properties of Cu ultra low-k dielectric materials for successful implementation in the semiconductor devices. The Cu ultra low-k systems are polished at different conditions of load and platen rotation and their polishing behavior is compared with the standard Cu-SiO2 system. The polishing behavior of Cu and the barrier Ta material is studied in order to effectively detect the end point of the Cu CMP process. Delamination studies, post process surface characterization using scanning electron microscopy and the reliability issues of these materials also come within the scope of this study.
Fabrication And Application Of Zeolite Membranes
Authors: Kita Hidetoshi 
Published: April 2011

ABSTRACTZeolite Membranes Were Prepared On A Porous Ceramic Support By Hydrothermal Synthesis Using Conventional Heating System And Microwave Heating. Naa And T Type Zeolite Membranes Were Highly Selective For Permeating Water Preferentially With The High Permeation Flux, While Silicalite Membranes Exhibited Preferential Organic Compound Permeation From Water Such As Ethanol/Water. Nay And Nax Zeolite Membranes Showed A High Alcohol Selectivity For Several Feed Mixtures With Methanol Or Ethanol And A High Benzene Selectivity For Benzene/Cyclohexane And Benzene/N-Hexane Separation. The Performance Of The Zeolite Membranes Was The Most Favorable One For Pervaporation Membranes Which Have Been Published So Far And A Tubular Type Module Using A Type Zeolite Membrane For Dehydration Of Organic Liquids Has Been Put Into Industrial Operation. The Tubular Type Pervaporation And Vapor Permeation Module Can Produce 99.8 Wt% Ethanol From 600 L/H, 90 Wt% Ethanol Feed At 120 °C. For The Mass Production Of Zeolite Membrane A New Synthetic Method Using A Microwave Heating Is Also Proposed.
Pervaporative Dehydration of an Industrial Ketonic Solvent Using Ceramic Silica Membranes
Authors: Urtiaga Ane M. , Casado Clara , Ortiz Inmaculada 
Published: April 2011

ABSTRACTIn this work, the dehydration of an industrial ketonic solvent used in the chemical industry is investigated by means of pervaporation (PV) using commercially available silica membranes (from Sulzer Chemtech and Pervatech BV). The solvent used is an industrial acetone-water mixture, with minor quantities of other reaction products. The initial water content is 30wt.%. The removal of water by PV has been previously experimentally studied using a polymeric Symplex membrane (GKSS), with relative success though the selectivity was low. Recent developments in the inorganic membrane field have led to the commercial availability of silica microporous membrane materials, like those used in this study. The performance of these ceramic membranes is compared, regarding their fluxes and selectivities. A simplified mathematical model is applied in order to be able to predict the pervaporation flux through pervaporation membranes.
The Zeolite ZSM-5 membrane study; synthesis, permeation and modeling.
Authors: Oonkhanond Bovornlak , Mullins Michael E. 
Published: April 2011

ABSTRACTZeolite particles formed in the synthesis solution assume a negative charge due to electrical double layer effects. The membranes synthesized via electrophoretic deposition produce a thin continuous zeolite ZSM-5 layer on the porous alumina substrates. The thickness of membranes can be controlled by varying the precursor concentration, applied potential, and synthesis time. The permeation for a variety of gases through the membranes is examined. The diffusion properties are measured at near ambient temperature and pressure. Selectivity of n-butane over iso-butane is observed on every membrane. The diffusion coefficient of gases on ZSM-5 is also evaluated by gas adsorption on zeolite powders. The results of these studies show an ability to predict the effective diffusion coefficients. The estimation of molar fluxes across the membranes using the Maxwell-Stefan approach predicts a higher flux for thinner membranes. However, the calculations also show that even minor defects in the membrane have a great effect on the permeation rates.
Selective Matrimid Membranes Containing Mesoporous Molecular Sieves
Authors: Balkus Kenneth J. , Cattanach Kyle , Musselman Inga H. , Ferraris John P. 
Published: April 2011

ABSTRACTWe have employed mesoporous molecular sieves in polymer membranes in an effort to enhance the permselectivity. The principal advantage of these materials is that the polymer chains can penetrate the pores reducing the nonselective voids that are often observed with inorganic additives. In this study, we have prepared Matrimid® membranes with various loadings of the all silica molecular sieve DAM-1 (Dallas Amorphous Material) as well as DAM-1 functionalized with amines in the channel wall, to enhance the gas permeability characteristics of a high performance polymer. For all gases tested (N2, O2, CO2, CH4), the permeability increased in proportion to the wt % of the amine DAM-1 present in the membrane. The addition of the amine DAM-1 resulted in modest ideal O2/N2 permselectivity, while the ideal CO2/CH4 permselectivity values were >100, depending upon the moisture content of the feed. The ideal CO2/CH4 permselectivity values are among the highest for this type of composite membrane. Details of membrane fabrication as well as permeability and permselectivity results will be presented for a range of Matrimid®/molecular sieve composites.
Numerical Solution of the Coupled Nernst-Planck and Poisson Equations for Ion-Selective Membrane Potentials
Authors: Lingenfelter Peter , Sokalski Tomasz , Lewenstam Andrzej 
Published: April 2011

ABSTRACTA numerical model is presented for analyzing the propagation of ionic concentrations and electrical potential in space and time in the solution ion-exchanging membrane system. Diffusion and migration according to the Nernst-Planck (NP) flux equation govern the transport of ions, and the electrical interaction of the species is described by the Poisson (P) equation. These two equations and the continuity equation form a system of partial non-linear differential equations that is solved numerically. As a result of the physicochemical properties of the system, both the contact/boundary potential and the diffusion potential contribute to the overall membrane potential. It is shown that interpreting the electrical potential of ion-exchanging membranes exclusively in terms of boundary potential at steady-state is incorrect. The Nernst-Planck-Poisson (NPP) model is general and applies to ions of any charge in space and time domains.
Orientation Dependence of the Texture Evolution in Cold-Rolled Thin Foils of Ni3Al Single Crystals
Authors: Kishida Kyosuke , Yozo Suga Masahiko Demura. , Hirano Toshiyuki 
Published: April 2011

ABSTRACTTexture evolutions of cold-rolled thin foils of binary stoichiometric Ni3Al single crystals were examined as a function of the initial crystal orientation. In the cases of the initial rolling direction (RD) close to <001>, the rolling texture above 90% reduction is composed of two {110}<112> textures, which resulted from the formation of the banded structure with two types of differently oriented matrix bands. The macroscopic shape of these cold-rolled foils is straight and simply elongated along RD keeping their rectangular shape. In contrast, when the initial RD is close to <112>, the texture and the microstructure are rather uniform but the foils are curved, twisted, and eventually cracked from the side edge of the samples. Based on the analysis of the texture evolution and the microstructure observation, the operative slip systems were determined.
Investigation on Additional Hardening Mechanisms in Off-Stoichiometric Al-Rich Ni3Al Alloys in Terms of Anti-Site Defect Configuration
Authors: Miura Seiji , Takizawa Satoshi , Mishima Yoshinao , Mohri Tetsuo 
Published: April 2011

ABSTRACTOne of the unsettled issues of the mechanical properties of L12-Ni3Al compound is the effect of off-stoichiometry on the 0.2% flow stress at low temperature region. 0.2% flow stress at 77 K increases as deviating from the stoichiometric composition to both Ni-rich and Al-rich sides, but in Al-rich side the increasing rate is higher. According to the XRD results for the binary Ni3Al alloys, however, the composition dependence of the lattice constant is the same in both sides of the stoichiometric composition, which implies that the magnitude of lattice strain induced at off-stoichiometric composition is symmetrical. And it is not rational to associate the strengthening mechanism to a sole effect of isotropic strain due to an atomic size difference. In this study, attempts are made to explain the additional strengthening in Al-rich alloys in terms of the tetragonal distortion hardening mechanism, which arises from anisotropic atomic configuration around an anti-site Al atom.
Transition Metal Alloying and Phase Stability in the Mo-Si-B System
Authors: Sakidja R. , Kim S. , Park J. S. , Perepezko J. H. 
Published: April 2011

ABSTRACTThe effect of transition metal substitution for Mo on the phase stability and multi-phase microstructures in the Mo-Si-B ternary system has been examined. The metal-rich portion of the ternary Mo-Si-B system at equilibrium is comprised of thermally stable BCC Mo(ss) phase, a ternary-based Mo5SiB2 (T2 phase), binary-based metal-rich silicides (Mo3Si [the A15 phase] and Mo5Si3 [the T1 phase]) and borides (Mo2B and MoB phases). Systematic alloying with selected transition metals which are substitutional in both Mo(ss) and T2 phases such as Cr, V, Nb, W, Ti and Hf, has been performed to elucidate the roles of the substitution on the stability of the three phase fields of Mo(ss) + T2 + A15 and T2+ T1 + A15. The potential of the alloying effects on the microstructure design and control of the solidification pathways is further detailed.
Eutectoid Phase Transformations in Nb-Silicide In-Situ Composites
Authors: Bewlay B. P. , Sitzman S. D. , Brewer L. N. , Jackson M. R. 
Published: April 2011

ABSTRACTNb-silicide based composites have excellent potential for future high-temperature structural applications. Nb-silicide composites possess Nb together with high-strength silicides, such as Nb5Si3 and Nb3Si. Alloying elements such as Ti and Hf, are added to obtain a balance of properties such as creep performance and oxidation resistance. In Nb-silicide composites generated from Nb-rich binary Nb-Si alloys, Nb3Si is unstable and experiences eutectoid decomposition to Nb and Nb5Si3. The present paper describes a low temperature eutectoid phase transformation during which (Nb)3Si decomposes into (Nb) and (Nb)5Si3, where the (Nb)5Si3 possesses the hP16 structure, as opposed to the tI32 structure observed in binary Nb5Si3.
Atomistic Studies of Dislocation Glide in γ-TiAl
Authors: Porizek R. , Znam S. , Nguyen-Manh D. , Vitek V. , Pettifor D. G. 
Published: April 2011

ABSTRACTComputer simulation of the core structure and glide of ordinary 1/2<110] dislocations and <101] superdislocations in L10 TiAl has been performed using the recently constructed BondOrder Potentials. This description of atomic interactions includes explicitly, within the tight-binding approximation, the most important aspects of the directional bonding, namely d-d, p-p and d-p bonds. The ordinary dislocation in the screw orientation was found to have a non-planar core and, therefore, high Peierls stress. The superdislocation was found to possess in the screw orientation either a planar (glissile) or a non-planar (sessile) core structure. However, the glissile core transforms into the sessile one for certain orientations of the applied stress. This implies a strong asymmetry of the yield stress and the break down of the Schmid law when the plastic flow is mediated by superdislocations. At the same time, this may explain the orientation dependence of the dislocation substructure observed in the single-phase γ-TiAl by electron microscopy.