bluuebunny/crossref_metadata_2025_split huggingface dataset:
Possible Artefacts in Measurement of Hardness and Elastic Modulus on Superhard Coatings and the Verification of the Correctness of the Data
Authors: Veprek S. , Mukherjee S. , Karvankova P. , Männling H.-D. , He J. L. , Xu J. , Prochazka J. , Argon A. S. , Li A. S. , Fang Q. F. , Li S. Z. , Manghnani M. H. , Tkachev S. , Zinin P. 
Published: April 2011

ABSTRACTMeasurements of the hardness and Young's modulus of superhard coatings (HV≥40 GPa) by means of automated load-depth-sensing indentation technique can be subject to a number of errors that are discussed and exemplified here. Only load-independent values of hardness for loads larger than 30–50 mN can be considered reliable when the technique of Doerner and Nix (linear extrapolation of the unloading curve) is used to determine the corrected indentation depth. The results are compared with values of Vickers hardness calculated from the contact area of the remaining plastic deformation which was measured by means of calibrated scanning electron microscope. The values of Young's modulus obtained from the indentation are close to the zero-pressure shear modulus of the coatings as measured by means of Vibrating Reed and surface Brillouin scattering techniques.
Adhesion Thin Ductile Films Using Stressed Overlayers and Nanoindentation
Authors: Cordill M. J. , Moody N. R. , Bahr D. F. 
Published: April 2011

ABSTRACTDifferently stressed films of tungsten on silicon dioxide have been studied to determine the interfacial fracture toughness and the Mode I fracture energy release rate of tungsten on glass. Tungsten films with a low compressive stress (less than 1GPa) had nanoindentation tests performed on them to induce buckling. Using mechanics based models and the dimensions of the buckles the fracture energy release rate and the phase angle of loading (Ψ) were calculated to be between 3.8 and 13 J/m2. By varying the residual stress in the film it was possible to examine regions of pure shear (Mode II) interfacial fracture as well as mixed mode interfacial fracture toughness of this system. A similar tungsten film was then used as stressed overlayer on sputtered Pt films on silicon dioxide to determine the fracture energy release rate. Nanoindentation was required to induce buckling, as the overlayer alone did not cause spontaneous buckling. The stressed overlayer method and nanoindentation were used to determine the interfacial toughness of the Pt/silica system to be 1.4 J/m2.
Novel Nanostructured Metal and Ceramic Composites
Authors: Narayan J. 
Published: April 2011

ABSTRACTWe have designed a unique synthesis procedure to create nonomaterials of uniform grain size and control the chemistry of interfaces between the grains. The metastability of nanocrystalline materials is a major challenge which can be addressed by controlling the chemistry of interfaces. The hardness of these films having a uniform size was measured as a function of grain size using a nanoindentation technique. It was found that hardness increased with decreasing grain size in accordance with Hall-Petch model. However, below a critical grain size we observed a decrease or softening with a further decrease in grain size. These observations in metals and ceramics are modeled in view of intragrain deformation (Hall-Petch regime) and intergrain deformation (grain boundary shear/sliding )in the softening regime. Since we can change the alloying of interfacial region, we can address the metastability as a function of temperature, which is crucial from applications viewpoint of these materials.
Novel Composite Coatings With 3D Coating Architectures for Tribological Applications Fabricated Using Semiconductor Patterning Processes
Authors: Krzanowski James E. , Endrino Jose L. , Hirschman Karl 
Published: April 2011

ABSTRACTComposite coatings consisting of hard compounds and soft solid lubricant phases have been actively investigated as tribological coatings for reducing friction while improving wear resistance. In most cases structural modifications in these coatings have been achieved by either natural phase separation or sequential layer deposition. In this study, we explore the concept of creating a three-dimensional structure in a tribological composite coating by using well-established semiconductor patterning methods. Using photolithography, we have patterned the substrate surface with a regular array of micron-size islands. The substrate was then coated with various metal and carbide coatings, including Cr and TiC, using sputter deposition. The substrates were sonicated in a solvent to remove the photoresist islands leaving an array of holes. MoS2 was then deposited onto the substrates. A pin-on-disk friction and wear test was conducted on a TiC/MoS2 sample to examine the effects of these islands on wear morphology. The results showed that the MoS2-filled holes can act as lubricant reservoirs, and the areas of the sample coated with TiC/MoS2 provided better wear protection than areas coated with only MoS2.
Nanocomposite Tribological Coatings for Rolling Element Bearings
Authors: Evans Ryan D. , Cooke Elizabeth P. , Ribaudo Carl R. , Doll Gary L. 
Published: April 2011

ABSTRACTThe performance of rolling element bearings is enhanced by the application of nanocomposite coatings that are composed of metal carbides incorporated into an amorphous hydrogenated carbon matrix (MC/a-C:H). When applied to the rolling elements in tapered roller bearings, MC/a-C:H coatings were found to help increase fatigue life, rib-roller end scuffing resistance, and false brinelling resistance in poorly lubricated environments. This series of performance tests were conducted with both coated and uncoated rollers. The results are attributed to the minimization of adhesive interactions and desirable counterface micro-polishing due to the presence of the thin hard coatings on rollers in the bearings.
Evaluation of Tribological and Mechanical Properties of Nitride Thin Films Prepared by Cathodic ARC Deposition
Authors: Shukla Pallavi , Sikder A. K. , Kumar Ashok , Durvin Robert , McDonough Mark , Smith M. D. 
Published: April 2011

ABSTRACTMechanical and tribological properties of thin films draw special attention and differ from those of bulk materials due to the effects of interfaces, microstructure and thick underlying substrates. In this study hard wear resistant nitride coatings (TiN, ZrN, TiAlN, TiCN and CrN) were coated on high speed steel substrates using cathodic arc deposition method. Mechanical properties of the films were evaluated using nanoindentation technique. Continuous stiffness method was employed to evaluate the depth sensing hardness and modulus values. Studies of tribological properties were performed using ball-on-disk friction and wear test. We have also investigated the wear track using optical microscopy. Variation of coefficient of friction with time has been analyzed and coating endpoint was estimated. Nanoindentation evaluation of mechanical properties along with the measurement of tribological properties is very useful in order to use them as wear resistant hard coatings.
MOCVD of Aluminum Oxide Barrier Coating
Authors: Nable Jun C. , Gulbinska Malgorzata A. , Suib Steven L. , Galasso Francis S. 
Published: April 2011

ABSTRACTHigh temperature materials such as nickel superalloys require the development of corrosion resistant coatings. These coatings must be thermally stable and chemically inert in order to protect the substrate material. Aluminum oxide is one such candidate. Aluminum acetylacetonate was used as the precursor for metal-organic chemical vapor deposition at atmospheric pressure. Uniform, amorphous, and multi-colored protective coatings were deposited onto nickel substrates at 400 to 500°C and dark gray, and powdery coatings were obtained at higher temperatures of 550 to 600°C. The coating was free from cracks when higher carrier gas flow rate were used.
Ion Beam Etching of CVD Diamond Enhanced by Prior Au and O Implantation.
Authors: Leech Patrick W. , Reeves Geoffrey K. , Holland Anthony S. , Ridgway Mark C. 
Published: April 2011

ABSTRACTDiamond films were implanted with Au or O ions at multiple energies in order to produce a uniform region of C vacancies. Analysis of the implanted films by Raman spectroscopy has shown that the proportion of non-diamond or amorphous carbon increased with dose (5 × 1013 − 5 × 1015 ions/cm2). For implantation with Au ions, a complete amorphisation near to the surface was evident at a dose of 5 × 1015 ions/cm2. We have examined the ion beam etch (IBE) rate of the films as a function of the implant species and dose. The etching experiments were performed using either Ar or Ar/O2 gases at a bias energy of 500 -1,000 eV. In Ar gas, the process of sputter etching has produced a similar increase in etch rate with dose for both the Au and O implants. In Ar/ O2 gases, the process of ion-enhanced chemical etching produced greater etch rates than obtained in Ar gas with higher rates for the Au than the O implants.
Double-wall Carbon Nanotubes Synthesized by the Abnormal Glow Discharge Plasma Method
Authors: Yoshikawa Hiromichi , Hoshi Fumiyuki , Kyotani Mutsumasa , Ishikura Takefumi , Yumura Motoo , Koga Yoshinori 
Published: April 2011

ABSTRACTDouble-wall carbon nanotubes (DWCNTs) and single-wall carbon nanotubes (SWCNTs) have been synthesized by the DC abnormal glow discharge plasma CVD method using methane and hydrogen gas on a Si substrate coated with catalyst. Fe(NO3)2 and Mo(CH3COCHCOCH3)2O2 with Al2O3 support were used as catalysts. The growth temperatures were 1000 − 1400°C and the gas pressures were 9kPa - 13kPa. DC plasma was generated between an array of four W cathodes and a Cu disk anode, and the applied power was 4000–10000W (2.5–4.0A per cathode, 400–800V). Samples were characterized by high-resolution transmission electron microscopy (HRTEM) and micro-Raman spectroscopy using 514.5 nm Ar ion laser excitation. The HRTEM images showed that many carbon nanotubes had a concentric cylindrical graphene layer structure (DWCNTs). We measured the diameters of the carbon nanotubes (CNTs) from HRTEM images. The outer diameter of the DWNT was 1.52–1.64nm and the inner diameter of the DWNT was 0.73–0.81nm.
Fabrication and Nonlinear Optical Characterization of Well-Ordered Nanopillar Arrays
Authors: Kuo Chun-Wen , Wu Shuo-Wen , Chen Peilin 
Published: April 2011

ABSTRACTSize-controllable nanostructure fabrication has drawn much of research attention lately, because it may allow the tuning of optical, magnetic, catalytic and electric transport properties of materials. To achieve this goal, we need to investigate the size dependent behavior of materials. The most popular method for size-controlled nanostructure fabrication is e-beam lithography. However, e-beam lithography is not an efficient process for large area fabrication. We report here a novel method to produce large area, well-ordered, size-controlled nanopillar arrays. Nanopillar arrays are among the most studied nanostructures because of their potential applications in photonic crystals, data storage, and sensors. To fabricate nanopillar arrays, we have employed both single layer and double layer nanosphere lithography. Nanosphere lithography, which uses the close packed structure formed by monodispersed colloidal particles as template, is known to produce large area, well-ordered nanostructures on substrate surfaces. These nanostructures have been utilized as the masks in the reactive ion etching process. By carefully controlling the gas composition and etching time, various sizes of nanopillar arrays have been produced. To characterize the optical properties of these nanopillar arrays, surface nonlinear spectroscopy has been used to investigate the size dependent response of nanopillar arrays.
A Simple Method of Tip Shape Calibration for Nano-Indentation Test of Thin Films
Authors: Hattori Koichiro , Xu Junhua , Nakano Hidetoshi , Kojima Isao 
Published: April 2011

ABSTRACTWe have evaluated the hardness and elastic properties of thin films by using a simple procedure to calibrate the tip shape effect of the nano-indentation data. For the simplification, a truncated-shape approximation and linear fit are used to estimate the tip-shape and contact stiffness, respectively, substituting for polynomial area-function and power-law fit. The parameters used in the correction were determined by a fused silica and a single crystal silicon (100) surface. Different film/substrate systems are designed in order to assess these fitted parameters used in the correction. The transition behavior observed from the film to the substrate is well coincide with the other film thickness results, where the indentation depth above 50nm.
Simple methods for measuring tensile and shear bond strength and for determining elastic modulus and strength of coating
Authors: Bao Yiwang , Zhou Yanchun 
Published: April 2011

ABSTRACTTwo new testing techniques, one is for evaluating the ceramics-ceramics and metal-ceramics bond strength, and one is for determining the elastic modulus and fracture strength of brittle coating, were developed respectively. Tensile and shear bond strength were obtained by using compression load on a cross-bonded samples. Rectangular section specimens with surrounding coating or single face coating were used for evaluating the mechanical properties of brittle coating. Analytical formula for the modulus calculation of coatings was derived based on the mechanics of materials. Stress analysis of coated beam provides the expression of the critical stress to fracture in the coating layer. Experimental results confirmed the reliability and convenience of this simple technique.
Mapping of Surface Residual Stress Field by Laser Interferometry Using Stress Relaxation Method
Authors: Kim Dong-Won , Lee Nak-Kyu , Na Kyung-Hoan , Kwon Dongil 
Published: April 2011

ABSTRACTBased on the identification of the residual stress-free state using electronic speckle pattern interferometry (ESPI), we modeled the relaxed stress in annealing, the thermal strain/stress and the residual stress field in case of both single and film/substrate systems by using the thermo-elastic theory and the relationship between relaxed stresses and displacements. Thus we mapped the surface residual stress fields on the indented bulk Cu and the 0.5μm Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -800 MPa to 700 MPa and -600 MPa to 600 MPa respectively around the indented point and in deposited Au film on Si wafer, the tensile residual stress is uniformly distributed on the Au film from 500 MPa to 800 MPa. Also we measured the residual stress by the x-ray diffractometer (XRD) for the verification of above residual stress results by ESPI.
Correlation of Stress and Phase Evolution in Thin Ta Films On Si (100) During Thermal Testing
Authors: French B. L. , Bilello J. C. 
Published: April 2011

ABSTRACTIn this study the stress and morphology of Ta coatings sputtered on Si (100) substrates were monitored in situ and in real-time during thermal testing to allow interruptions at critical events in the coatings' stress evolution. These observations were carried out using white beam Laue transmission diffraction topography/radiography and a high-temperature sample stage at the Stanford Synchrotron Radiation Laboratory (SSRL). The structure of specimens from interrupted thermal tests was then analyzed using x-ray diffraction θ-2θ scans. The structure and phases present in the film at different stages of the thermal test were correlated with specific mechanical responses in the coating such as stress generation. This information was employed to elucidate the role of phase evolution in the respective stress responses of films deposited in high and low-pressure regimes.
Surface and Interface Characterization of Ion Beam Re-crystallized Si
Authors: Sahoo P. K. , Satpati B. , Dey S. , Satyam P. V. , Som T. , Kulkarni V. N. 
Published: April 2011

ABSTRACTIn the present work we have studied efficacy of ion beam induced epitaxial crystallization (IBIEC) to recover amorphous layers (300 – 350 nm) produced by MeV Kr ions in Si(100) and studied the associated changes occurring on surface and interface of the recrystallized region. IBIEC experiments were carried out at sample temperatures in the range of 200 − 400°C using 1 MeV N+ ion beam. Rutherford backscattering-Channeling technique showed planar and gradual recovery of the amorphous layer as a function of temperature. Transmission electron microscopy measurements show good crystalline structure of the recovered region at 400°C while at lower temperatures nano-crystalline Si formation embedded in the amorphous structure is evident. The surface topography studied by atomic force microscopy shows development of islands after IBIEC. The rms roughness is around 0.5 nm and average height of the islands is found to be 1.8 nm. The observed epitaxial growth and the surface topographical features have been correlated.
Multispinneret Methodologies for High Throughput Electrospun Nanofiber
Authors: Bowman Jeremy , Taylor Malcolm , Sharma Vikram , Lynch Anne , Chadha Suneet 
Published: April 2011

ABSTRACTThe overall objective of the Electrospinning program at Foster-Miller is to develop a semi-automated, pilot scale machinery capable of producing nanofiber membranes at reasonable scales so that they can be evaluated for a wide range of military and commercial applications. This paper discusses the development of a high throughput electrospinning process
Anisotropic Hydrogen Permeation in Nano/Poly Crystalline-Nickel Membranes
Authors: Cao Y. , Li H. , Szpunar J. A. , Shmayda W. T. 
Published: April 2011

ABSTRACTBilayer nickel membranes have been prepared using electrodeposition to grow polycrystalline nickel on a nanocrystalline nickel substrate. When hydrogen is charged from the nano-Ni side of the nano-Ni and poly-Ni composite membrane, the permeation current increases rapidly, then the membrane releases hydrogen faster during decay. When hydrogen is charged from the poly-Ni side of the same composite membrane, the permeation current rises gradually and takes a longer time to reach steady state. Also the permeability of nano-poly-Ni membrane is eight times higher than that of poly-nano-Ni membrane. The diffusivity for the nano-Ni side charging in a nano-poly-Ni membrane is two times higher than that of poly-Ni side charging of the same membrane. The diffusivity and permeability of nano-poly-Ni membranes are smaller than those for nano-Ni membranes, but larger than those for poly-Ni membranes. Using this anisotropic behavior, one can manipulate hydrogen permeation through composite membranes. A hydrogen permeation model for bilayer membranes is proposed to simulate diffusion in a nano-Ni and poly-Ni bilayer membrane in two-directions of charging. The experimental data is in good qualitative agreement with the model.
Effects of Bleach Reprocessing on Hemodialysis Membranes
Authors: Wolff Susanne H. , Zydney Andrew L. 
Published: April 2011

ABSTRACTHemodialysis membranes are exposed to bleach during standard reprocessing methods, but there is little quantitative understanding of the effects of bleach on the mass transfer characteristics or surface properties of these membranes. A battery of experiments was used to evaluate the effects of bleach on the properties of Fresenius F80A, F80B, and Optiflux 180A dialyzers. Bleach caused a significant increase in the membrane hydraulic permeability. The clearance of urea (MW=60 Da) increased by only 3% after a 1-hour exposure to bleach at 50 °C compared to more than a 10-fold increase in the clearance of a 15 kD MW dextran. The solute clearance data were used to determine the effective membrane pore size using available hydrodynamic models. Bleach caused a significant increase in the effective pore size, which was attributed to the leaching of the polyvinylpyrrolidone (PVP) out of the polysulfone membrane. Bleach also caused a significant increase in the magnitude of the negative charge on the membrane surface; the zeta potential varied from −4.1 mV for the new membrane to −13.0 mV after a 14-hour exposure to bleach. These changes in pore size and surface properties provide important insights into the effects of bleach on hemodialysis membranes.
Aromatics Enrichment in Refinery Streams using Solvent Resistant Membranes
Authors: White Lloyd S. , Wildemuth Craig R. 
Published: April 2011

ABSTRACTPermselective separation of aromatic from non-aromatic hydrocarbons in feed streams can be accomplished by using membrane systems in hyperfiltration mode. In petrochemical or refinery operations, feed streams containing aromatics such as benzene, toluene, or xylenes can be selectively enriched or depleted in aromatics content. The development program for the STARMEM™ series of membranes led to a commercial process for their large-scale manufacture. A range of membranes in terms of flux and selectivity has been made, and both 2-inch and commercial scale 8-inch diameter spiral wound elements manufactured from these membranes. Tests at 800 psi (55 bar) and 50 °C with a toluene recycle stream have shown stable operation of these modules in hot hydrocarbons. The high efficiencies of these modules allow for high stage cuts (50% and greater) from process streams of thousands of barrels per day. By combining existing refinery operations such as distillation with these new membrane units, cost savings through better purity, recovery, or through-put can be achieved. With these membranes acting as tight hyperfiltration devices, the permeation properties can be modeled through a solution-diffusion equation for molecular transport. Since these membranes also act as solvent resistant nanofiltration devices, unusual benefits can be found while practicing aromatics enrichment of refinery streams, including fractionation of different molecular weight species.
The Preparation of Partially Oriented Zeolite Thin Films via Pulsed Laser Ablation
Authors: Deng Zhongsheng , Pisklak Thomas J. , Balkus Kenneth J. 
Published: April 2011

ABSTRACTThin films of zeolites including silicalite-1, mordenite and UTD-18 have been prepared on stainless steel foil via pulsed laser deposition (PLD). Laser ablation of as-synthesized zeolite targets onto stainless steel foil followed by a post hydrothermal treatment results in partially oriented zeolite thin films. SEM, XRD were used to characterize the zeolite thin films. Preliminary results for multilayercoatings of different zeolites will also be presented.
Hydrophilic, heat stable, low protein binding surface modification of PVDF membranes
Authors: Charkoudian John , Xenopoulos Alex , Lynch John 
Published: April 2011

ABSTRACTProtein binding studies reveal increased levels of protein adsorbed to thermally treated poly-acrylamide-modified PVDF microporous membranes in comparison to polyacrylate-modified membranes. Application of XPS, ToF-SIMS, densitometry and μthermal AFM indicate poly-acryamide-PVDF mixing as the primary cause of the increased protein binding.
Preferential Oxygen Transport in Nanophase Mesoporous Ceramic Ion Conducting Membranes
Authors: Guizard C. , Levy C. , Dalmazio L. , Julbe A. 
Published: April 2011

ABSTRACTRecent data from the literature dealing with the influence on oxygen transport of porous nanophase ion conducting ceramics are reviewed, and then transposed to the design of mesoporous nanophase ceria-based membranes. Mesoporous CeO2/Al2O3 and Gd doped CeO2 membranes containing Pd and Pt nanoparticles were prepared using the sol-gel process. Permeation of N2 and O2 single gases was studied in a temperature range 20–500°C. Permeation measurements indicate an activated oxygen transport in agreement with the literature data. A synergetic effect of the noble metal nanoparticles on oxygen transport has been evidenced, in relation with the triple phase boundary concept. However, these membranes do not perform totally the preferential oxygen transport predicted by the theory. Several directions are proposed for membrane improvement, in particular concerning pore and grain optimal sizes.