bluuebunny/crossref_metadata_2025 huggingface dataset:
Solid State Primary & Secondary Batteries & Composite Electrode Theory
Authors: Akridge James R. , Jones Steven D. , Vourlis H.
Published: March 2011

The concept of a solid state energy storage cell has been proven technically feasible by numerous researchers over a period of at least 30 years. [1] Good reviews are available on the state of the art today [2]. The related concept of a solid state rechargeable cell has also been proven technically feasible [3,4]. This paper will describe advances made in primary and secondary solid state cell systems over a period of several years of development at Eveready Battery Co., Inc. Additionally, an attempted experimental verification of “Composite Electrode Theory” proposed by S. Atlung [5] is made.
High Temperature Humidity Sensing Materials
Authors: Tsai Ping Ping , Tanase Shigeo , Greenblatt Martha
Published: March 2011

New proton conducting materials were prepared and characterized for potential applications in humidity sensing at temperatures higher than 100°C by complex impedance or galvanic cell type techniques. Calcium metaphosphate, β-Ca(PO3)2as a galvanic cell type sensor material yields reproducible signals in the range from 5 to 200 nmm Hg water vapor pressure at 578°C, with short response time(-30 sec). Polycrystalline samples of α-Zr(HPO4)2and KMO3P5.8Si2O25, and the gel converted ceramic, 0.10Li2O-0.25P2O5-0.65SiO2as impedance sensor materials show decreases in impedance with increasing humidity in the range from 9 nmn Hg to 1 atm water vapor pressure at 179*C.
Enhanced Ionic Conductivity in Composite Electrolytes
Authors: Dudney Nancy J.
Published: March 2011

The ionic conductivity of a large number of electrolyte materials, such as LiI, AgCl, AgI and CuCl, is known to be enhanced by the addition of inert submicron particles, most often alumina. Typically the conductivity is enhanced by I to 3 orders of magnitude for composites containing 10 to 40 volume % particles. Several other researchers have attributed this effect to an enhanced carrier concentration in a space charge polarization layer surrounding the alumina particles. However, estimates of the magnitude of such a space charge layer indicate that this mechanism alone can not account for the large enhanced conductivities reported for several of the composites.
Non-Random Mixing and Fast ion Decoupling in Lithium Chloroborate Superionic Glasses: An Ion Dynamics Computer Simulation Study
Authors: Syed R. , Kieffer J. , Angell C.A.
Published: March 2011

Li+ions are highly mobile in LiCl-Li2O·2B23glasses to the extent that the decou-pling of conductive modes of motion from the viscous modes, assessed at the glass transition temperature Tgby a relaxation time ratio, is one of the greatest known. The interpretation of the structure of this glass system and its relation to conductivity decoupling is not very advanced at this time but there seems to be a distinction drawn between the chloroborate structure and the structure of the corresponding AgCl-Ag borate and AgI-borate glasses. The latter have frequently been discussed in terms of α-AgI percolating clusters although the available thermodynamic evidence indicates chemical ordering (negative deviations from ideal mixing) as opposed to any sort of clustering (positive deviations from ideal mixing). The LiCl-Li2O-B2O3system is interesting to us because simple transferable effective pair potentials are available for all species in the system and ion dynamics computer simulations should be capable of giving useful insights into the structure, energetics, and dynamics of the system. We present diffusivity data as a function of temperature for several compositions in the LiClLi2O·2B2O3system and observe that the Li+mobility remains high below the simulated, glass transition. Surprisingly, the Cl−anion mobility also remains high, raising a question about anion transport numbers in these glasses. Computed conductivities agree with laboratory data in the liquid state but exceed laboratory data in the glassy state in the direction expected from the high fictive temperature of simulated glass. Deviations from additivity in mixing energy in this system show a weak tendency to clustering of LiCl in the structure which suggests a need for laboratory mixing enthalpy studies.
Accelerated Chloride Ion Diffusion Test
Authors: El-Belbol Said M. , Buenfeld N. R.
Published: March 2011

This paper presents a new test method for rapidly assessing the resistance of a concrete to chloride ion diffusion.
Investigations On The Water Vapor Permeability Of Cementitious Materials Ivan Odler And Hans-Peter Barthold
Authors: Odler Ivan , Barthold Hans-Peter
Published: March 2011

The migration of water vapor through the existing pore system was studied on a series of cementitious, hydrothermally produced and ceramic materials with open porosities ranging between 18 and 79 per cent. Regardless on the nature of the material the water vapor migration rate increased linearly with open porosity. As to the effect of pore size, the apparent diffusion coefficient was moderately greater in pores with radii above 100μm than in smaller pores. As to the effect of relative humidity the water migration rate was greatest at high humidities and exhibited a moderate minimum at about 20–40% r.h.. At equlibrium conditions the amount of water bound in the pore system of samples through which water vapor was alloved to migrate was consistently lower than in identical samples in which just water vapor adsorption took place.
A Model for the Distribution of Pore Sizes in Cement Paste
Authors: Shi D. , Brown P. W. , Kurtz S.
Published: March 2011

The pore size distribution in cement paste over the range of pore sizes interrogated by high pressure mercury intrusion porosimetry may be described by a mixture of two lognormal distributions. The compound distribution of pore sizes may be given as:

where p(x) is the probability density function of pores of size x, f and (1−f) are the weights of sub-distributions, μ1 and μ2 are the location parameters of sub-distributions, and σ1 and σ2 are the shape parameters of sub-distributions. These two sub-distributions may represent the larger and smaller capillary pores respectively. The changes in the sub-distributions and the compound distribution as functions of curing age and water-to-cement ratio are discussed.
An Investigation Of A High Speed Shear Mixer On Selected Pastes And Mortars
Authors: Brown M. L. , Ledbetter W. B. , Jennings H. M.
Published: March 2011

The influence of shear mixing on selected properties of cement pastes and mortars was investigated by preparing specimens using an ordinary paddle mixer and a high speed shear mixer. The results appear to indicate that shear mixing influences the bond between paste and aggregate, particularily at low water:cement ratios. The properties of hardened cement paste did not change markedly as a result of high speed shear mixing used in this initial study.
Influence Of Curing On Surface Characteristics Of Concrete
Authors: Sadegzadeh M. , Kettle R. J. , Page C. L.
Published: March 2011

An experimental assessment is presented of the influence of curing regimes on the abrasion resistance of concrete. Specimens have been produced from several different mix compositions and the abrasion resistance has been measured using a rolling-wheel apparatus. To explore these relationships, microstructural features of the cement matrix components of the surface have been studied by mercury intrusion porosimetry. The results indicate the abrasion resistance of concrete is controlled by the pore structure of the surface matrix. The nature of the curing regime having significantly influenced the pore size distribution and total pore volume of the surface matrix of the concrete surface.
A Study on the Relationship between Pore Structure and Coefficient of Permeability of Soil Stabilized with Cement
Authors: Kunito Toshimitsu , Honda Atsuhiro , Mashima Miho , Hamasato Seishi
Published: March 2011

This study is aimed at the quantitative evaluation of the impermeability of soil-cement in relation with soil conditions, mix proportions and curing ages. Considering the permeability coefficient as the macro property and the pore size distribution as the micro property, this paper presents the relationship between the permeability coefficient and the pore size distribution of the soil-cement. From this study, a dense soilcement with dispersed fine voids is recommended to improve the impermeability of the soil-cement.
Precipitation of Oxygen and Mechanism of Stacking Fault Formation in Czochralski Silicon Bulk Crystals
Authors: Wada Kazumi , Inoue Naohisa , Osaka Jiro
Published: March 2011

This paper describes recent progress on nucleation and growth of oxide precipitates and stacking faults in Czochralski silicon. Conclusions on the growth kinetics of oxide precipitates are drawn from the experiments and analysis of growth kinetics of two-dimensional precipitates: The experimentally obtained growth kinetics, three-quarter power law is theoretically derived and the precipitate growth is demonstrated to be diffusion-limited by oxygen interstitials. The formation mechanism of stacking faults is the Bardeen-Herring mechanism. Based on diffusional growth model, the growth kinetics of stacking faults are analyzed, assuming a coexistence of self-interstitial supersaturation and vacancy undersaturation. It is found that the growth is driven by vacancies in undersaturation. Vacancy component of self-diffusion has been determined and found to be predominant at low temperature. The possibility of growth model proposed for increase of oxide precipitate density during annealing has been excluded. Both processes, homogeneous and heterogeneous nucleation, have been taking place during annealing.
Carbon and the Kinetics of Oxygen Precipitation in Silicon
Authors: Pinizzotto R.F. , Marks S.
Published: March 2011

Oxygen precipitation in Czochralski silicon has been studied as a function of anneal time, oxygen concentration and carbon concentration using FTIR. It was found that the oxygen supersaturation controls the precipitation kinetics in high oxygen content samples, whereas the carbon concentration is of prime importance in low oxygen content samples. The decrease in sustitutional carbon concentration after nucleation and its subsequent increase with extended growth anneals supports the view that carbon affects precipitate nucleation, but not precipitate growth. The measured oxygen solubility at 1000°C was found to depend on both the initial oxygen concentration and the initial carbon concentration.
Effect of Oxygen on Radiation-Enhanced Diffusion in Silicon
Authors: Borisenko V.E.
Published: March 2011

Low-energy ion bombardment has been used to enhance diffusion of phosphorus and antimony atoms in silicon. Oxygen free silicon crystals both containing phosphorus and antimony doped surface layers and original crystals were bombarded at 400–700°C with 400 eV oxygen or argon ions. Impurity and electrical carrier profiles were measured to analyse the role of oxygen in the radiationenhanced diffusion. The results obtained are explained on assuming complexes such as vacancyoxygen and vacancy-substitutional impurity to be involved in the process.
Photoluminescence Study of Thermally Treated Silicon Crystals
Authors: Weber J. , Sauer R.
Published: March 2011

Cz silicon samples heated to 450 ° C or higher temperatures for several hours exhibit many sharp photoluminescence lines well below the band edge. We study the production of the lines in terms of carbon and oxygen doping and of the heating temperature and duration. First results as to a level scheme of the P (0.7672 eV) line are reported.
Oxygen Precipitation Effects in Degenerately – Doped Silicon
Authors: Rozgonyi G. A. , Jaccodine R. J. , Pearce C. W.
Published: March 2011

In this paper we report preliminary observations of oxygen precipitation in degenerately-doped silicon using etching, optical microscopy and transmission electron microscopy. It was found that n+ material was resistant to precipitation, but p+ material precipitated readily. A multistep heat treatment starting with a low temperature step to achieve a high supersaturation ratio was sucessfully used to induce precipitation in n+ material.
Point Defect Thermodynamics of Compound Semiconductors and their Alloys
Authors: Kröger F. A.
Published: March 2011

The physical properties of crystalline solids depend on the presence of point defects. The concentrations of these defects in turn depend on the conditions of preparation and the presence of dopants. Quantitative relations between these conditions (partial pressures of components, concentrations of dopants, temperature) and the defect concentrations is arrived at on the basis of defect chemistry. Examples of pure and doped binary compounds, alloys of binary compounds, and ternary compounds, are given. Whereas binary compounds have one composition variable, the alloy systems and the ternary compounds have two. The role of phase diagrams in preparing systems of required composition and properties is stressed.
Self-Diffusion in Compound Semiconductors
Authors: Willoughby Arthur F.W.
Published: March 2011

Self-diffusion studies are vital in the elucidation of atomic mechanisms of diffusion; as well as in the better understanding of device fabrication processes, such as the annealing of ion-implanted layers. This review outlines first the major reasons for interest in self-diffusion in III–V and II–VI compounds. It discusses the main differences with elemental semiconductors, including the wide variety of possible defects in the compounds, the role of departures from stoichiometry, and the value of tracer and interdiffusion studies. Self-diffusion studies in III–V compounds are next reviewed, including recent measurements in GaAs, where more information on diffusion mechanisms is becoming available. Interdiffusion between different III–V compounds is also discussed in the light of self-diffusion studies. Next, recent progress on self-diffusion in certain II–VI compounds is discussed, where interdiffusion studies have also provided a significant contribution. The review concludes by suggesting areas where research is urgently needed to clarify diffusion mechanisms.
Electrical Properties of Dislocations and Boundaries in Semiconductors
Authors: Queisser Hans J.
Published: March 2011

Simple models have been suggested to predict electronic properties of lattice defects in semiconductor crystals: dislocations ought to act via the acceptor character of dangling bonds, and small-angle grain boundaries ought to consist of regular arrays of dislocations. The actual situation in most semiconductors is, however, much more complicated. The observed electrical effects of dislocations do not confirm the dangling-bond concept, they are affected by dissociation and reconstruction. There appear to be differences between straight and kinked dislocations. Dislocations owe much of their electronic behavior to clouds and precipitates of impurities; oxygen in silicon plays a significant role. This review summarizes the present status of experimental methods and results, including luminescence and capacitance spectroscopy as well as mapping and imaging techniques using electron-microscopes.
Electronic States of Grain Boundaries in Bicrystal Silicon
Authors: Shyu C. M. , Cheng L. J. , Wang K. L.
Published: March 2011

Electronic states at a 20° symmetrical(100) tilt boundary in p-type silicon were studied using deep level transient spectroscopy (DLTS) and other electrical measurements. The data can be explained with a model in which the local barrier height at the grain boundary varies on a scale much smaller than the boundary plane (∼I mm2) under study. Based on a relationship between the carrier capture cross section and energy level deduced from the experimental data, we have been able to calculate the distribution of the density of states in the energy bandgap at the boundary, which contains two groups of continuously distributed states; a major one whose density of states increases monotonically with the position of the state from the valance band, and a minor narrow one whose density of states is centered at Ev,+0.20 eV.
The Effect of Oxygen in Cosputtered (Titanium + Silicon) Films
Authors: Beyers R. , Sinclair R.
Published: March 2011

The effect of oxygen incorporation on the growth and microstructure of TiSi2 has been investigated. Cosputtered films, with Si/Ti ratios between one and three, were deposited on (100) Si substrates and reacted at temperatures from 650° to 1050°C. Both Auger electron spectroscopy, in conjunction with sputter profiling, and Rutherford backscattering spectrometry indicate that oxygen in the as-deposited films redistributes to the silicide-silicon interface upon heating. Cross sectional transmission electron microscope images show that the oxygen is present as an amorphous oxide.
Investigations of Metal-Silicon Interfaces by Time-of-Flight Atom Probe.
Authors: Grovenor Christopher , Smith George
Published: March 2011

The use of a Time-of-Flight Atom Probe in the analysis of silicon surfaces, and the interfaces between metals and silicon, promises to provide very accurate chemical analysis allied with structural information from Field Ion Microscopy images. This paper presents results on the analysis of silicon surfaces by this technique,showing that good spectra can be obtained without difficulty. Some preliminary experiments on the structure of such specimens after the deposition of thin layers of Pd and Ni will be described,concentrating on the analysis of the stoichiometry of the reacted layers.
The Growth of Epitaxial NiSi2 Single Crystals on Silicon by the Use of Template Layers
Authors: Tung R. T. , Gibson J. M. , Poate J. M.
Published: March 2011

A novel crystal growth technique for NiSi2 epitaxy is presented which utilizes thin silicide (<60Å) template layers to pin the subsequent growth under ultrahigh vacuum conditions. Single crystalline NiSi2 films can be grown with either type A or type B orientations on Si(111). Continuous single crystalline NiSi2 is grown on Si(100) with flat interface and uniform thickness.
Correlation of Structure and Properties of Silicon Devices
Authors: Marcus R. B.
Published: March 2011

Three types of structure-related problems in VLSI materials and the impact of these problems on device properties are discussed: substrate defects and device leakage/breakdown, metallization linewidth and device failure, and SiO2/polysilicon interface texture and device leakage/breakdown. In many cases transmission electron microscopy is the major source of information on structure.
Donage and in Situ Annealing During Ion Implantation
Authors: Sadana D. K. , Washburn J. , Byrne P. F. , Cheung N. W.
Published: March 2011

Formation of amorphous (α) layers in Si during ion implantation in the energy range 100 KeV–11MeV and temperature range liquid nitrogen (LN)-100°C has been investigated.Cross-sectional transmission electron microscopy (XTEM) shows that buried amorphous layers can be created for both room temperature (RT) and LN temperature implants, with a wider 100 percent amorphous region for the LN cooled case. The relative narrowing of the α layer during RT implantation is attributed to in situ annealing. Implantation to the same fluence at temperatures above 100°C does not produce αlayers. To further investigate in situ annealing effects, specimens already containing buried α layers were further irradiated with ion beams in the temperature range RT-400°C. It was found that isolated small α zones (< 50 Å diameter)embedded in the crystalline matrix near the two α/c interfaces dissolved into the crystal but the thickness of the 100 percent α layer was not appreciably affected by further implantation at 200°C. A model for in situ annealing during implantation is presented.
A Comparison of Ellipsometer and Rbs Analysis of Implant Damage in Silicon
Authors: Paulson W. M. , Wilson S. R. , White C. W. , Appleton B. R.
Published: March 2011

The purpose of this study is to analyze ion implant damage profile using RBS and ellipsometry. Silicon wafers were implanted with 75As at 100, 200 or 300 keV; doses were chosen to generate constant peak impurity concentrations at each energy. The samples were then analyzed using RBS to obtain damage- depth profiles and ellipsometry to obtain Δ,ψ parameters. At light doses decreasingΔ values correspond to increased scattering yield; at higher doses ψ increases rapidly as the scattering yield approaches the random value. The higher energy implants shift the Δ-ψ curves to larger ψ values. Multilayer structures, that include lightly damaged silicon on either side of the project range as well as more damaged near the projected range, are required to model the ellipsometer parameters.
The Study of Damage Profile of Ion Implanted Layer on Si by Spectroscopic Ellipsometry
Authors: Luo Jinshen , Mc Marr P.J. , Vedam K.
Published: March 2011

We have determined the dielectric function of silicon samples which were implanted with 100-150 KeV P, As, Si ions to doses of 2·1014-1·1016cm−2, by a rotating analyser Automated ellipsometer in the spectral range 1.77− 4.59 eV. These data have been analyzed using a simplified three layer model.The results are compared with an earlier ellipsometric investigation [2].
Si-On-Sapphire and Si Implanted with Zr Ions: Lattice Location, Solid Phase Epitaxial Regrowth, and Electrical Properties
Authors: Golecki I. , Suni I.
Published: March 2011

Zr ions have been implanted at 300 keV (Rp= 1400Å) and doses of 3×1012 − 3×l015 Zr/cm2 into Si-implanted, amorphous Sip layers on (100) bulk Si and Sion- sapphire. Rutherford backscattering and channeling spectrometry was used to study the Zr distribution and lattice location during solid-phase regrowth of the Si layers. The regrowth at 500—550°C stops at 3.4хl020 Zr/cm3, and Zr exhibits interface trapping and surface segregation effects. In this temperature range, Zr is essentially non-substitutional, and inactive electrically.
Defects in Amorphous Silicon
Authors: Biegelsen D. K.
Published: March 2011

In this paper we argue that amorphous silicon can be treated as a relaxed continuous random network. The optical and electronic properties are controlled by localized gap states which arise from characteristic features of a disordered tetrahedrally-bonded covalent network. Experimental results are reviewed which indicate that the dominant (perhaps only) electrically-active defect in hydrogenated amorphous silicon is the topologically distinct, silicon dangling bond. Finally, we suggest that the same, disorder-related characteristics might also typify the electronic properties of some macroscopic crystalline silicon defects.
Metastable Defect Configurations in Semiconductors
Authors: Benton J. L. , Levinson M.
Published: March 2011

Deep Level Transient Spectroscopy is used to examine the stability of defect configurations in Si and InP. A systematic approach has been developed to study alternate structures of metastable defects through their representative electronic states. Regulation of defect charge state prior to analysis reveals dramatic transformations in the resulting spectra. These defect states are metastable and can be controlled with thermal or electronic energy. Model studies in electron irradiated InP and Si are presented. The barriers to configurational change are determined from the reaction kinetics. The roles of electric field, minority carrier injection and charge state are explored through junction bias techniques. It is believed that the observed behaviors represent a new class of defect reactions. The systematics of detecting and studying these reactions are presented. Model defect structures are discussed.
Micromechanics and Microdynamics Via Atomistic Simulations
Authors: Landman Uzi , Luedtke W. D. , Ribarsky M. W.
Published: March 2011

Basic understanding of the structure and dynamics of materials and their response to external perturbations requires knowledge on the microscopic level, of the underlying energetics and atomic dynamics, whose consequences we observe and measure. Coupled with the above is the everlasting quest to observe and understand natural phenomena on refined microscopic scales, which provides the impetus for the development of experimental and theoretical techniques for the interrogation of materials with refined spatial and temporal resolution. In this paper we review the development of molecular dynamics simulations for studies of the energetics and dynamical response of materials to external mechanical perturbations. Applications to investigations of solid and liquid interfacial systems under stress and to studies of the consequences of tip-substrate interactions in atomic force microscopy are demonstrated.
Tribology of Amorphous Alloys Formed with Ion Beams
Authors: Follstaedt D. M. , Knapp J. A. , Pope L. E.
Published: March 2011

The changes in friction and wear properties (i.e., tribology) of steels due to thin surface alloys formed by ion beams are surveyed, and considered in light of their microstructures. Amorphous alloys containing both Ti and C are found to give superior performance in comparison to alloys with N, B, C, P or Ti. All the amorphous layers reduce friction, but the duration of benefits and wear resistance at high loads vary with composition. By examining similar amorphous alloys with Ti alone or C alone, the critical roles played by each in resisting wear are demonstrated. Amorphous alloys with Ti and C appear to be quite hard.
Tribological and Mössbauer Studies of Ion-Implanted Iron
Authors: Williamson D.L. , Qu Yi , Wei Ronghua , Sampath W.S. , Wilbur P.J.
Published: March 2011

A modified pin-on-disc wear test technique and conversion electron M6ssbauer spectroscopy (CEMS) have been used to characterize the tribological and microstructural properties, respectively, of pure Fe implanted with N and Ar ions at high current densities. CEMS measurements were made before and after wear testing. For the lubricated, mild adhesive wear conditions used here, no evidence was found for iron-nitride dissolution or N atom migration. Disordering of γ'-Fe4N did occur as a result of the wear process. All Nimplanted surfaces were tribologically superior to the Ar-implanted surface and an extremely wear-resistant surface layer about 30-50 nm thick was produced with a dose of 8x1016 N atoms/cm2, at a dose rate of 100 μA/cm2. However, once this layer was worn away the wear rate returned sharply to that of unimplanted pure Fe. A high retained N dose has been observed even for a dose rate of 750 μA/cm2 during which the sample reached 280°C.
Friction Characteristics of B+- and N2+-Implanted Fe-Cr Alloys.
Authors: Sasaki Jun , Iwaki Masaya
Published: March 2011

A study has been made on friction and hardness of boron and nitrogen ion implanted Fe-Cr alloys. Ion implantation has been carried out with doses ranging from 5 wt% up to 20 wt% at energies of 50, 100 and 150 keV at room temperature. Reciprocal traces for friction coefficient measurements were performed by using a Bowden-Leben tester at a low speed without lubricant. Hardness was measured by using a micro-Vickers tester at a load of 2gf. Hardness of the specimen increases after the implantation with either of ion species. Friction measurements with reciprocal sliding show that a life-time of decreased friction coefficient depends on implanted ion species, Cr concentrations and acceleration energies. For B+- implantation, the lower the chromium contents are, the longer a decreased friction coefficient lasts. Meanwhile, the friction reduced by nitrogen implantation lasts longer for higher chromium content substrates. Dependence of friction coefficient on an acceleration energy is discussed for B+-implantation.
Unlubricated Sliding Properties of Ion Beam and Excimer Laser Mixed Fe-Ti-C Multilayered Films
Authors: Hirvonen J-P. , Nastasi M. , Jervis T.R. , Tesmer J.R. , Zocco T.G.
Published: March 2011

Multilayered Fe-Ti-C films consisting of eleven sublayers were vacuum deposited onto an AISI 304 stainless steel substrate and subsequently mixed using either 400 keV Xe ions or an excimer laser operating at a wavelength of 308 nm. Ion mixing was accomplished in a two step process: the multilayers were first irradiated with 1xl017 Xe/cm2 at 520 °C, after which half of the sample was irradiated with 5x1015 Xe/cm2 at 0 °C. Laser mixing was carried out at both 1.1 and 1.7 J/cm17 with the number of pulses varied between 1 and 10. Pin-on-disc studies revealed only slight differences between the two kinds of ion beam mixed samples, whereas the dry sliding properties of laser mixed samples were strongly dependent on the total fluence used. In the optimum conditions, similar friction coefficients were obtained on both kinds of samples.
Surface Mechanical Properties of Ti Alloys Produced by Excimer Laser Mixing of Ti on AiSi 304 Stainless Steel
Authors: Jervis T. R. , Hirvonen J-P. , Nastasi M. , Zocco T. G. , Martin J. A. , Pharr G. M. , Oliver W. C.
Published: March 2011

We have investigated the properties of surface alloys of Ti formed by excimer laser melting and mixing of Ti overlayers on AISI 304 stainless steel substrates.The thickness of the initial Ti surface layers and the fluence and number of pulses used to mix the surface were varied toinvestigate a broad range of processing conditions. Samples were uniformly translated at different speeds under repetitive pulses of homogenized laser radiation at 308 nm to vary the number of pulses incident on the sample. We investigated the surface structure and composition, the wear and friction behavior, and the surface hardness of the resulting alloys.

The extent of mixing is observed by Rutherford backscattering spectroscopy to be proportional to the number of pulses incident on the sample. Amorphous surface layers are formed at some mixing levels with a composition which indicates that Ti substitutes for Fe in the stainless steel on a one to one basis. Incorporation of C from surface and interface contamination is observed but at a level much below that found in comparable ion implanted materials.

Friction coefficient measurements indicate that there exists an optimum level of mixing for each layer thickness. Excessive mixing degrades both the coefficient of friction and the wear performance in dry sliding tests.

As with the tribological measurements, the surface hardness showed a dependence on amount of mixing. The surface hardness of the as deposited samples was higher than that of the laser mixed samples, initially decreased with mixing, and finally increased with further mixing.
Solid Lubricating Films for Extreme Environments
Authors: Singer Irwin L.
Published: March 2011

Advances in solid lubricating films for vacuum and high temperature applications are reviewed. Traditional lubricants (e.g. graphite and dichalcogenides) are being improved and new lubricating materials (e.g. amorphous carbons) are being discovered with the aid of recent developments in deposition processes and surface analytical methods. Ion bombardmenttreatments have increased film adhesion, lowered friction coefficients and enhanced the wearlife of MoS2films, as well as created new forms of lubricating carbons (amorphous, polymeric and diamond-like). Composite films and multilayer coating treatments are providing extra protection for surface and films against environmental degradation. Ultralow friction coefficients (<0.01) have been achieved with MoS 2 as well as diamond-like carbon films. Material selection, in some cases (e.g. thin metal films), can nowbe made basedon scientific principles, although many tribomaterials are still being developed by trialand error methods.
Modifications of Molybdenum-Disulphide Films by Ion-Bombardment Techniques
Authors: Mikkelsen Niels JØrgen , SØrensen Gunnar
Published: March 2011

The present paper reports on the structural and tribological studies of MoSx films in the thickness range of 3-4000 Å bombarded with inert-gas ions in the hundred-keV energy range. It has been shown that it is possible to amorphize MoS1.8 crystalline films with 400-keV Ar ions at a dose of lxl016 ions/cm2 Contrary to previous studies, there is evidence for both a lowfriction coefficient and an increased sliding life of sputtered MoSx films when amorphized by the ion-bombardment technique. The paper will discuss the influence of ion dose and tribological differences between bombarded and nonbombarded MoSx films. With the availability ofhigh-intensity ion beams in the mA range, the possibility of a direct ion synthesis of a molybdenum surface with high-intensity sulphur-ion beams will be discussed, and friction measurements of these systems will be presented.
Tribological Applications for Advanced Ceramics
Authors: Jahanmir S.
Published: March 2011

Advanced structural ceramics offer unique capabilities as tribomaterials. They are being used today in diverse applications such as tips for ball-point pens, precision instrumentbearings, and cutting tool inserts. Tribological applications of ceramics can be divided into several categories based on the properties of the ceramics. These include: resistance to abrasion and erosion; resistance to corrosive wear; wear resistance at elevated temperatures; low density; and electrical, thermal and magnetic properties. Examples of present utilization of ceramics in each category are described and a few examples of potentialfuture applications are given. Many scientific and technical barriers must be overcome before the full potential of ceramics in tribological applications is realized. These barriers are discussed in terms of the limited knowledge regarding tribological performance, problems with reliability, and lack of design knowledge and experience. It is clear that the wide-spread use of advanced ceramics requires further research and development. However, it must be realized that the solutions to the scientific and technical problems will be slow.
The Effect of Surface Finishing on the Tribological Behavior of a 94% Alumina Ceramic Material
Authors: Spodnik Jeffrey L. , Wert James J.
Published: March 2011

The effect of surface finish on the unlubricated sliding wear behavior of a 94% A12O3 ceramic material has been investigated using a reciprocatingright cylinder-on-flat tribometer. The surface finishes evaluated were produced using a combinationof SiC and diamond abrasive particles.

Profilometry was employed to characterize surface topography and x-ray diffraction was used to determine the residual stress associated with each finishing process.

The coefficients of friction and controlling wear mechanisms varied dramatically as the maximum asperity height was altered by different finishing techniques. Below a peak profile of 0.25 μm, the coefficient of friction varied between 0.60 and 0.75 due to preferential shearing of the siliceous binder phase which segregated at surfacial pores and grain boundaries. Binder adhesion in the sliding contact produced stick-slip frictional behavior. Surfaces with asperity heights in excess of 10 μin exhibited intergranularfracture or grain “pluck-out”. These surfaces contained minimal real areas of contact and yielded friction coefficients of 0.30 - 0.35. Removed alumina grains actedas hard abrasives in the contact zone and enhanced transgranular fracture by a lateral cracking mechanism. Evidence of crack propagation as a result of Mode II and Mode III shearloading was discovered at subsurface pore sites. The influences of microindentation hardness and fracture toughness are discussed in terms of their relative importances on the observed wear behavior.
The Tribooxidative Behavior of Rutile-Forming Substrates
Authors: Gardos Michael N.
Published: March 2011

An assessment of the literature indicates that in high temperature air not only titanium,but also titanium carbide (TiC) and titanium nitride (TiN) react to form rutile, the mostthermodynamically stable polymorph of titanium dioxide. It has been recently hypothesizedthat slightly oxygen-deficient rutile (TiO2-x) behaves as a low shear strength, lubricious oxide.

Although the oxidation kinetics-driven reaction of the less stable TiC results in thickeroxide layers than on TiN, the most prevalent film morphology and oxide structure on both TiC and TiN are the same as those generated on the much softer Ti and its alloys. In mostcases of static oxidation and tribooxidation at high temperatures, the oxide layers grow in extremely thin (1 to 5 μm) sheets, which periodically delaminate from the substrate. The kinetics of delamination are highly dependent on substrate properties. These sheets form an array of loosely cohering (under static conditions) or tightly cohering (under triboconditions) scales, similar to the morphology of multilayered pastry dough. The most thermodynamically stable [(110)] cleavage planes of rutile tend to align preferentially in the plane of the peeling flakes, but without any azimuthal order. It is suggested that rutile can be rendered lubricious (a) by this unique structure, (b) by keeping its shear strength minimal by intrinsic (i.e., environment-independent) control of the number of oxygen vacancies within the oxide layers, and (c) by tailoring the load-carrying substrate used to form the rutile films in-situ. Accordingly, the removal rate ofrutile and the friction coefficient provided by the oxide/substrate tribosystem may be further controlled by taking advantage of (a) the high, but still significantly different hardnesses and ideal habit plane orientation of the TiC and TiN mother matrix underlays, and (b) the differences in the reaction kinetics of layered oxide growth on these highly oriented, hard metal coating matrices at elevated temperatures, in air.
Tribochemical Lubricious Oxides on Silicon Nitride
Authors: Fischer T. E. , Liang H. , Mullins W. M.
Published: March 2011

The concept of lubrication by a tribochemically generated oxide layer on the surface of silicon nitride is further investigated. Previous work has shown that low friction coefficients (μ≈0.1) are obtained in a range of sliding velocities and loads when otherwise unlubricated silicon nitride slides in humid air at temperatures between 150 and 650ºC. In order to verify the hypothesis that this behavior results from a competition between the growth of an oxide layer (with growth kinetics accelerated by friction) and its removal by wear, we have performed model experiments at room temperature, wherethe oxide layer is grown statically (i.e. without friction) and the friction coefficient and its evolution in time are subsequently measured. In order to avoid high friction by plowing, ultraflat surfaces were first prepared by sliding in water. The experiments showed that the oxide layer growing in humid air on silicon nitride produces a friction coefficient as low as μ≈0.05 that survives about 30 Newton meter of sliding, which corresponds to several hundred passes of the counterface. When sliding in water, the surface acquires a high friction coefficient (μ≈0.7) very rapidly. The difference in the lubricating properties of tribochemical surface layers on aluminum oxide and silicon nitride can be understood on the basis of the differing surface chemistries of these materials. We offer a tentative lubrication mechanism based on low adhesion between the oxide surface and the silicon nitride counterface and the structure of oxides grown inhumid ambients.
Fundamentals of Tribology at the Atomic Level
Authors: Ferrante John , Pepper Stephen V.
Published: March 2011

Tribology, the science and engineering of solid surfaces in moving contact, is a field that encompasses many disciplines: solid state physics, chemistry, materials science, and mechanical engineering. In spite of the practical importance and maturity of the field, the fundamental understanding of basic phenomena has only recently been attacked. In this paper we will attempt to define some of these problems and indicate some profitable directions for future research. We make three broad classifications: (1) fluid properties--compression, rheology, additives and particulates; (2) material properties of the solids--deformation, defect formation and energy loss mechanisms; and (3) interfacial properties--adhesion, friction chemical reactions, and boundary films. Research in the categories has traditionally been approached by considering macroscopic material properties. Recent activity has shown that some issues can be approached at the atomic level: that is, the atoms in the materials can be manipulated both experimentally and theoretically, and can produce results related to macroscopic phenomena. This experimental and theoretical activity is reviewed and related to the traditional research areas.
Surface Analysis of Fretting Damage in Electrical Connectors
Authors: Braunović M.
Published: March 2011

A number of bolted-type tin-plated copper connectors commonly used for distribution transformers were examined using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDX). The connectors studied had been removed from service because of unsatisfactory performance under normal operating conditions as manifested either by overheating or instability.Detailed examination revealed the presence of extensive fretting damage in thecontacting surfaces. The fretting debris was composed mainly of tin oxide and oxidized base-metal particles. Localized melting and wear of the tin plating were also observed.
Monte Carlo Simulation of Adsorption of Di-Block Copolymers
Authors: Shih Wan Y. , Shill Wei-Heng , Aksay Ilhan A.
Published: March 2011

In this paper we are concerned with the morphology of the polymers adsorbedon surfaces, in particular di-block copolymers. Our work is motivated by the experimental findings of Fladziioannou et al. [1] on the steric forces between two adsorbed layers of di-block poly(vinyl-2-pyridine)\ polystyrene (PV2P\ PS) copolymer on mica surfaces. The PV2P block binds strongly on the mica surfaces and the PS block extends into thesolvent toluene (good solvent for PS). Hadziiouannou et al. found that the repulsive forces between the two surfaces start at a distance 1) larger than 10 times the radius of gyration RG of a free P' in toluene. Furthermore, the starting distance D increases with increasing degree of polymerization N of PS in a fashion I) ~ Na with a close to I. We,tudy the adsorption of di-block copolymer with Monte Carlo simulations. The Monte Carlo simulations are especially powerful in dealing with kinetics which is important in systems where hysteresis is observed II1 and cannot be appropriately taken into account by analytical (or numerical) calculations based onequilibrium assumptions.
Development of the Computer Controlled Seizure Testing Methodology
Authors: Dubrovsky R. , Shih I-Tsung
Published: March 2011

In this paper the computer controlled methodology and the testing apparatus were developed and designed to study seizure as a destructive wear. The seizure testing methodology is based on obtaining the power losses information in testing zone during any time of testing period. These losses are dueto the different friction coefficient in the area of load and sliding zone.They can be automatically recorded and recomputed into the friction force and\or friction coefficient. The friction force and\or friction coefficient - sliding distance relationship can be plotted and the starting point of mass transfer which results in increasing the friction coefficient can be detected. The test results are presented using developed methodology as well as traditional optical microscope and surfanalyzer.
Sliding Wear of Metallic Materials at 25 and 550 ºC.
Authors: Fischer A.
Published: March 2011

A new wear tester for temperatures up to 1100ºC is introduced. Firstresults of sliding wear tests are shown and discussed. Due to enhanced tribooxidation at 550ºC the wear rates of one-phase materials are lower compared to those measured at 25ºC. The wear rates of hard phase containing alloys increase with temperature, because the metal matrices loose their capability of supporting the hard phases bringing about additional abrasion.
The Adhesion and Deformation Properties of CVD TiC Coated Bearing Balls Under Heavy Loads
Authors: Hanson Robert A.
Published: March 2011

CVD TiC coatings on steel bearing balls have been demonstrated to improve conventionally lubricated instrument bearing performance and life, particularly where wear mechanisms predominate. Lightly loaded, approximately 1,400 (200 ksi) MPa maximum Hertz stress, coated bearing balls have run billions of load cycles without coating integrity failure. Data is presented to characterize the behavior of TiC coated steel balls under heavy loads, to approximately 4,200 MPa (605 ksi) maximum Hertz stress, for 175,000 load cycles. As in the lightly loaded tests, there was no indication of coating integrity failure, ie. cracks or delamination. At loads of 2,500 MPa (364 ksi) and above, somewhat below the elastic limit of the 440C substrate, there was evidence of plastic deformation of the coated surface.
Improvement of the Wear Resistance of Magnetic and Vitreous Substrates Coated with Thin Diamond Like Carbon Layers
Authors: Meunier P.L. , Texier F. Le , Coutellier J.M. , Mackowski J.M.
Published: March 2011

Results of wear tests on VTR carried out on magnetic and nonmagnetic dummies coated with a thin (20-30 nm) diamond-like carbon are reported.

The diamond-like carbon thin films have been obtained by two techniques : RF Plasma Deposition by decomposition of hydrocarbon and Dual Ion Beam Sputtering (DIBS). The first one is more suitable for vitreous materials such as S1O 2, Fotoceram, and magnetic material Sendust (FeSiAI) though DIBS technique turned out to be the proper candidate for polycrystallines Ferrite Substrates.

A multilayer : diamond-like Carbon\Sendust\A120 3TiC dummy (25nm\3 itm\Substrate) tested on VTR tapes at 5 ms-1 exhibited a 3000 h life time without significant wear.
Utilization of Ultrasonic Measurements to Quantify Aging-Induced Material Microstructure and Property Changes
Authors: Doctor Steven R. , Bruemmer Stephen M. , Good Morris S. , Charlot Larry A. , Taylor T. Thomas , Boyd Donald M. , Deffenbaugh John D. , Reid Larry D.
Published: March 2011

Many structural components are exposed to thermal environments that promote aging-induced changes in material microstructure and properties. The extent of these changes may lead to a reduction in the design safety factors and, as a worst case, premature failure of the component. In order to illustrate how nondestructive measurements can be used to indicate these changes, ultrasonic measurements were conducted on stainless steel. Specimens from a high-carbon, Type 304 stainless steel were subjected to various thermal treatments to introduce differing precipitation morphologies. Specimens were examined using transmission electron microscopy to quantify the size, density, and distribution of the precipitates formed. Ultrasonic measurements were performed to assess sensitivity to the change in precipitation levels. Shear-wave birefringence provided the most consistent measurements for tracking precipitate morphology changes. Birefringence velocity differences increased as precipitate size and density increased on grain boundaries and as additional precipitates formed in the matrix. The ability to nondestructively monitor the precipitation process is important since susceptibility to environmentally assisted cracking and low-temperature embrittlement correlated with this microstructural change.