International Nuclear Information System (INIS)

A carbon nanotube (CNT) tip, which assembled on the sharp end of a Si tip by dielectrophoresis, was structurally modified using focused ion beam (FIB). We described the imaging characterization of the FIB-modified CNT tip in noncontact AFM mode in terms of wear, deep trench accessibility, and imaging resolution. Compared to a conventional Si tip, the FIB-modified CNT tip was superior, especially for prolonged scanning over 10 h. We conclude that modified CNT tips have the potential to obtain high-quality images of nanoscale structures.

Energy Technology Data Exchange (ETDEWEB)

The sliding friction and wear behaviour of different steel qualities were investigated with and without lubrication conditions. Steel qualities tested are normally used in the overhead conveyor system of many industrial fields, like the automotive sector. Sliding wear tests have been conducted by means of a pin-on-disk machine. A 100Cr6 steel similar to that used within the overhead conveyor trolleys has been employed as a pin. Friction coefficient values obtained under lubrication conditions were three times smaller than those obtained without lubrication. The mechanism that controls wear behaviour under lubrication conditions is an abrasive one and the wear values obtained are almost worthless. On the other hand, mechanism controlling wear during non lubrication tests, was a combination of abrasion and adhesion. (Author) 20 refs.

British Library Electronic Table of Contents (United Kingdom)

To improve the friction and wear behavior of carbon fabric reinforced polymer composites (CFRP), nano-SiO2 was deposited on the fabric surface. The friction and wear behavior of the resulting composites were investigated on a model ring-on-block test rig. Experimental results revealed that fiber surface treatment contributed to largely improve the tribological properties of the CFRP composites. Scanning electron microscope (SEM) investigation showed that the worn surface of the surface modified CFRP composite was smoother under given load and sliding rate. Field emission scanning electron microscopy (FESEM), FTIR and X-ray photoelectron spectroscopy (XPS) studies of the carbon fiber surface showed that nanostructured Sio2 thin film can be obtained by SiO2 sols deposition, which improved th...

Science.gov (United States)

Ceramic and Dental Enamel Wear

International Nuclear Information System (INIS)

Topographic and optical patterns have been fabricated in a-SiC films with a focused high-energy (1 MeV) H"+ and He"+ ion beam and examined with near-field techniques. The patterns have been characterized with atomic force microscopy and scanning near-field optical microscopy to reveal local topography and optical absorption changes as a result of the focused high-energy ion beam induced modification. Apart of a considerable thickness change (thinning tendency), which has been observed in the ion-irradiated areas, the near-field measurements confirm increases of optical absorption in these areas. Although the size of the fabricated optical patterns is in the micron-scale, the present development of the technique allows in principle writing optical patterns up to the nanoscale (several tens of nanometers). The observed values of the optical contrast modulation are sufficient to justify the efficiency of ...

Energy Technology Data Exchange (ETDEWEB)

There is presently considerable interest in wear resistant coatings produced using closed field unbalanced magnetron sputtering technology. For example, layered films of diamond-like carbon (DLC) with tungsten or titanium additions have been widely reported. The benefit is that the mechanical properties are enhanced (e.g. giving greater toughness); also it is possible to control the stress state and enhance adhesion. Here we report the further development of this concept by the addition of TiN, TiCN and TiC layers in DLC-based composites, utilizing an additional source of electrons in the vicinity of substrate to enhance ionisation of the plasma and increase coating density. Composite coatings of ceramics TiN, TiC{sub x}N{sub y}, TiC, CrN, TiCrN, TiCrCN, TiCrC, metal doped Ti{sub x%}-DLC and their combinations were deposited on 316 stainless steel substrates. The mass flow of reactive gases into the chamber was controlled using plasma optical ...

British Library Electronic Table of Contents (United Kingdom)

Residual stresses are present in engineering components as an unintended consequence of manufacturing processes, but they are also deliberately introduced to beneficial effect during surface engineering procedures. Plasma nitriding is a process of particular importance for forming tools and dies, giving significant advantages in wear, and fatigue resistance through the generation of near-surface compressive residual stresses. A precise knowledge of the level and distribution of residual stresses that exist in engineering components is necessary for an accurate design and prediction of a component's fatigue resistance. However, measurement of residual stresses is not always possible, which is especially true for forming tools. Therefore, other methods for residual stress evaluation and pred...

International Nuclear Information System (INIS)

The usually low wear resistance of titanium materials can be increased by the thermochemical surface treatment nitriding. In result of comparative investigations of gas and plasma nitriding it will be shown that it is possible to obtain a specific variation of the properties in the highly stressed case by means of these both technologies on example of the (#alpha#+#beta#) alloy Ti-6Al-4V. Gas and plasma nitriding was carried out in the temperature range from 650 to 800 C over 4 to 48 h in different gas atmospheres, i.e. 100% NH_3 (gas), 100% N_2 (gas and plasma), 20% H_2 + 80% N_2 and 20% Ar + 20% H_2 (plasma). The temperature range was fixed in the middle of (#alpha#+#beta#) region, because the core properties are influenced negative in the field of #beta#-transustemperature. The relations between the applied nitriding technologies, the layer structure (chemical, phases, geometrical) and selected layer properties (microroughness, ...

Science.gov (United States)

... Title : Wear Rate and Friction Coefficient in Liquid Nitrogen and Hydrogen of Steel Sliding on Polymer Laminates (Various Fabrics and Polymers. ...

Energy Technology Data Exchange (ETDEWEB)

Out of the R and D of mesoscopic metal group composite materials, the paper described the fiscal 1997 results. In the in-situ method as a composite material making method, elucidated to some degree were chemical composition of Fe-C-Cr-V-Nb-Mo-W-Ni base multi-dimensional alloys, and wear resistance and oxidation resistance of MC type carbide dispersion multi-phase texture crystallizing as primary crystal and eutectic. In the composite material making with ceramic fiber and alloy by the pressure infiltration method, the paper clarified the texture formation mechanism in solidification/heat treatment by a combination of Al alloys and alumina long fiber, and the relation between fiber configuration and wear resistance. By MA and MG methods as the powder metallurgy composite material making method, a composed body of {alpha}-stainless steel of Fe-12%Cr composition and M23C6 of 40-90vol% are designed for alloy composition, and powder of amorphous or ...

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

The organization of organic semiconductor molecules in the active layer of organic electronic devices has important consequences to overall device performance. This is due to the fact that molecular organization directly affects charge carrier mobility of the material. Organic field-effect transistor (OFET) performance is driven by high charge carrier mobility while bulk heterojunction (BHJ) solar cells require balanced hole and electron transport. By investigating the properties and device performance of three structural variations of the fluorenyl hexa-peri-hexabenzocoronene (FHBC) material, the importance of molecular organization to device performance was highlighted. It is clear from {sup 1}H NMR and 2D wide-angle X-ray scattering (2D WAXS) experiments that the sterically demanding 9,9-dioctylfluorene groups are preventing {pi}-{pi} intermolecular contact in the hexakis-substituted FHBC 4. For bis-substituted FHBC compounds 5 and 6, {pi}-{pi} intermolecular ...

Energy Technology Data Exchange (ETDEWEB)

The wear behaviour of 722M24 (En40B) steel plasma nitrided at high temperatures for long durations was investigated. Under dry sliding and abrasive-containing lubricated conditions, the wear characteristics of the steel were studied as a function of load, time and white layer thickness. The white layer and the wear debris were characterized by X-ray diffraction. The topography of the wear surface was examined in a scanning electron microscope. The plasma nitriding process was carried out using a 20 kW plasma processing unit in cracked ammonia atmosphere. Treatment times of up to 100 h were employed with temperatures of 550, 570 and 590 C. Wear tests were performed with plasma nitrided AMS 6472 as the counterface material. The tests under abrasive-containing lubricated conditions were carried out with 10% carborundum powder 10 [mu]m in size in SAE-30 machine oil. The ...

International Nuclear Information System (INIS)

Fretting wear test in room temperature water was performed to evaluate the wear coefficient of CANDU (CANadian Deuterium Uranium) steam generator (SG) tube material (Alloy 800) against 410 type martensitic stainless steels. The main focus is to compare the wear behaviors between Alloy 800 and Inconel 690. Test conditions are 10#approx#30N of normal load, 200#approx#450mm of sliding amplitude and 30Hz of frequency. The result indicated that the wear rate of Alloy 800 was higher than those of Inconel 690 at various test condition such as normal loads, sliding amplitudes etc. From the results of SEM observation, there was little evidence of plastic deformation layer that were dominantly formed on the worn surfaces of Inconel 690. Also, wear particles in Alloy 800 were released from contacting asperities deformed by severe plastic flow during fretting wear. Main ...

Science.gov (United States)

Electric utilities have been surprised by recent opposition to the construction of very-high-voltage transmission lines, which met with little resistance in the past. Concerns over health and safety factors are associated with the increase in the number of such lines, although their presence has always been an inconvenience and a hazard for those living and working in the immediate vicinity. The new lines present additional hazards due to the continuous flow of small electric currents and the charges that build up in the area of the towers and lines. The lines are also a threat to persons wearing cardiac pacemakers. There is experimental evidence from the Soviet Union and the U.S. that electric and magnetic fields at the frequencies of such power lines can have serious biological effects on growth rates and the functioning of the central nervous system. Full disclosure that possible risks are involved and the opportunity to avoid these risks is ...

Energy Technology Data Exchange (ETDEWEB)

Laser surface alloying with gaseous nitrogen was utilized to improve the wear resistance of a Ti-6Al-4V alloy. Wear-resistant composite coatings reinforced by hard TiN dendrites were produced 'in-situ' on a substrate of a Ti-6Al-4V alloy. The hardness and wear resistance of the laser alloyed coating under two-body abrasive and block-on-ring full-sliding wear conditions were significantly enhanced. (orig.)

Energy Technology Data Exchange (ETDEWEB)

To make the surface composites with hard ceramics particles is an effective means for satisfying the request for the wear-resistance of the casting products. Covering casting is a general method for forming the composites by adding the adhesive into ceramics particles. However, due to the using of adhesive, pore and intermediate are easy to generate, and it is one of the reasons making the wear-resistance unstable. In the present study, it is attempted to form the wear-resistant composite layer by dispersing cast tungsten carbide (CTC) particles on the surface of wear-resistant 7 mass% Mn steel without using adhesives. Subsequently, the experiments on the wear-resistance of the obtained surface composites under several wear conditions are carried out. It is revealed by the results thereof that 7 mass% Mn steel surface composites with CTC particles have the ...

Energy Technology Data Exchange (ETDEWEB)

The tribological behavior of SiSiC/100Cr6-, Si/sub 3/N/sub 4//100Cr6- und Al/sub 2/O/sub 3//100Cr6-pairs has been investigated with oscillating load on a spherical disc/disc tribometer. The prevailing wear mechanism of the Si ceramics is tribooxidation, which leads to the formation of a SiO/sub 2/ protective layer with a reduction in friction and wear. With frequencies >1 kHz, this effect increases, resulting in low friction coefficients and wear rates. The prevailing mechanism of the oxid ceramic is surface fatigue. The hard wear particles produce severe abrasive wear. This effect is intensified with higher frequencies.

Science.gov (United States)

This dissertation presents the development of the novel mechanical testing technique of in situ nanoindentation in a transmission electron microscope (TEM). This technique makes it possible to simultaneously observe and quantify the mechanical behavior of nano-scale volumes of solids.

Energy Technology Data Exchange (ETDEWEB)

Engineering materials for use in low heat rejection engines are required to function under stringent tribological conditions. Severe wear damage and high friction between the components of the tribosystem limit the number of potential materials suitable for such application conditions. The superalloys X-750 and 188 are composed of alloying elements that not only promote a high mechanical and chemical stability but may also result in a reduced wear rate and friction coefficient at elevated temperatures. As a part of the DOE-ECUT Tribology program at Argonne, the present study was undertaken to evaluate the tribological characteristics of these alloys that will also be utilized as the substrates for ion beam deposited lubricous coatings. A wear test rig that crudely simulated the sliding conditions between a piston ring and a cylinder liner in an operating engine was utilized for friction and wear ...

International Nuclear Information System (INIS)

Full Text: Smallstage Dualbeam (SDB) systems, that is a Focussed Ion Beam column coupled with a SEM column, have been around for about five years now. There impact on the Semiconductor industry has been enormous, with virtually every lab having a SDB to produce, characterise and analyse cross sections and TEM samples on the Nano-scale. But what about other industries? What else can SDB system be used for? The SEM column in itself is a very powerful tool for sample characterisation, modification and analysis. An electron beam from a Tungsten or Thermal Field Emission source has enough current to allow sophisticated patterns to be created in photo-resist samples, a process known as lithography. The current is also high enough to allow for a process known as Electron Beam Induced Deposition (EBID), where the beam interacts with an introduced gas and material is deposited in a controlled manner on the sample. With the addition of the Focussed Ion ...

International Nuclear Information System (INIS)

A series of ball-on-disc wear and friction measurements were made for surfaces which have a chemical vapour deposition carbon silicon alloy layer on a carbon substrate (fine grain POCO graphite). Nitrogen ion irradiation was used to improve the wear resistance of the carbon alloy surface. For comparison, measurements were also taken for alumina against alumina. It was found that the lowest friction coefficient and lowest wear occurred for ion irradiated coated samples containing 4% Si in the alloy and that the performance was superior to that of alumina. ((orig.)).

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

Very good friction and wear measurements are reported for MRCC (metal reinforced carbon composites), made from low-wear non-graphitic carbon matrix with metal-fiber reinforcement. Counterfaces include austenitic and martensitic stainless steels, Si nitride, and alumina. Effects of high load, high temperature, and gaseous environments are reported: removal of humidity, atm. oxygen have little effect on friction, wear for MRCC sliding against ceramic or stainless steel. Wear of Al oxide riders on MRCC is very low, not affected by contact load. 260 C temperatures do not degrade performance of 440-C riders on MRCC disks or raise friction. In small or large sizes, MRCC is made in a single-pass process for about the same volume cost as cast iron. It can survive heating in nitrogen above 1600 C without loss of integrity or major change of dimensions.

British Library Electronic Table of Contents (United Kingdom)

Two types of representative nanometer materials, i.e., fibroid nanometer attapulgite and approximate spherical ultrafine diamond, were selected as fillers of polytetrafluoroethylene (PTFE) to study the mechanism of the wear-reducing actions of the fillers in PTFE composites. The friction and wear tests were performed on a block-on-ring wear tester under dry sliding conditions. Differential scanning calorimetry (DSC) was used to investigate material microstructure and to examine modes of failure. No significant change in coefficient of friction was found, but the wear rate of PTFE composites was orders of magnitude less than that of pure PTFE. DSC analysis revealed that nanometer attapulgite and ultrafine diamond played a heterogeneous nucleation role in PTFE matrix and consequently resulte...

International Nuclear Information System (INIS)

Current light water reactor (LWR) steam generators have been affected by a variety of corrosion and mechanical damage degradation mechanisms. Included are wear caused by tube vibration, intergranular corrosion, pitting, and thinning or wastage of the steam generator tubing and accelerated corrosion of carbon steel supports (denting). The Electric Power Research Institute (EPRI) and the Steam Generator Owners Groups (I, II) have sponsored laboratory and field studies to provide ameliorative actions for the majority of the damage forms experienced to date. Some of the current corrosion mechanisms are aggravated or caused by unique materials choices or materials interactions. New materials have been proposed and at least partially qualified for use in replacement model steam generators, including an advanced LWR design. In so far as possible, the materials choices for the advanced LWR steam generator avoid the corrosion pitfalls seemingly inherent ...

Energy Technology Data Exchange (ETDEWEB)

Titanium alloys are characterized by poor tribological properties, and the traditional use of titanium alloys has been restricted to nontribological applications. The deposition of a well adherent diamond coating is a promising way to solve this problem. In this study, the tribological properties of diamond-coated titanium were studied using a pin-on-disk tribometer, and the results were compared with those of pure titanium and plasma nitrided titanium. The tribological behavior of pure titanium was characterized by high coefficient of friction and rapid wear of materials. Plasma nitriding improved the wear resistance only under low normal load; however, this hardened layer was not efficient in improving the wear resistance and the friction properties under high normal load. Diamond coating on pure titanium improved the wear resistance of titanium significantly. Surface profilometry measurement ...

Energy Technology Data Exchange (ETDEWEB)

Youngkwang Unit 3,4 and Ulchin Unit 3 and 4 have had problem of the KSNP Steam Generator due to a severe fretting wear on the tube. In particular, the wears were localized and concentrated in the upper part of U-bend of the Central Cavity region. At the upper tube bundle Central Cavity, the fluid flow velocities and void fraction are very high, because the steam is made by high heat transfer at secondary region. Also, this region is affected easily by fretting wear due to it's unsupported span is longer than another regions. The fretting wear is assumed to be result of Flow-Induced Vibration (F. I. V), which can occur by many mechanisms. EFDP was added to UCN 5,6 for prevent fretting wear by the SEC LCC and DSHIC, a company of design and manufacture of the steam generator, respectively. In order to evaluate the efficacy of EFDP, ANSYS and ATHOS-3 Code were used. From ...

International Nuclear Information System (INIS)

The tool materials durability problem, in particular shock and wear resistance, has allowed to formulate a set of requirements and also to stablish the dependence between physical properties and wear. However, for understanding the nature of the process, for example determining the tribological property of the cutting tool, it is necessary to consider the atom interactions in a crystal. A theoretical study of the physical properties of cutting tool materials (W-Ti-C) with varying concentration of titanium is presented. Total and partial local electronic density for each atom in such hard solutions were calculated. (nevyjel)

Energy Technology Data Exchange (ETDEWEB)

Extensive experimental investigation has been carried out on used flight bearings of the high pressure oxidizer turbopumps (HPOTP) of the space shuttle main engine (SSME) in order to determine the dominant wear modes, their extent, and causes. The paper presents the methodology, various surface analysis techniques used, results, and discussion. The mode largely responsible for premature bearing wear has been identified as adhesive/shear peeling of the upper layers of bearing balls and rings. This mode relies upon the mechanisms of scale formation, breakdown, and removal, all of which are greatly enhanced by the heavy oxidation environment of the HPOTP. Major causes of the high wear rates appear to be lubrication and cooling, both inadequate for the imposed conditions of operation. Numerous illustrations and evidence are provided. 22 refs.

International Science & Technology Center (ISTC)

Corrosion- and Wear Resistant Silicon Containing Chromium-Manganese and Nickel-Chromium-Manganese Nonmagnetic Steels with Increased Strength and Toughness for Reliable Work at Normal and Cryogenic Temperatures

UK PubMed Central (United Kingdom)

The incidence of candidiasis in two groups of voluntary participants wearing tight and loose fitted dresses was investigated by both microscopic and cultural techniques for a period of two months....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Energy Related Inventions Program Number 613 was a two year program to commercialize a unique new wear material, Metal Reinforced Carbon Composite, MRCC. The program was designed to manufacture sample components of MRCC for evaluation by potential users and manufacturers. As a result of the program Burton Technologies Inc. and Rotary Power International are forming a joint company to manufacture, market and license MRCC materials to a wide range of industries.

Energy Technology Data Exchange (ETDEWEB)

This study investigates the effect of solid and liquid lubrication on friction and wear performance of silicon nitride (Si{sub 3}N{sub 4}) and cast iron. The solid lubricant was a thin silver film ({approx}2 {mu}m thick) produced on Si{sub 3}N{sub 4} by ion-beam-assisted deposition. A high-temperature polyol-ester-base synthetic oil served as the liquid lubricant. Friction and wear tests were performed with pin-on-disk and oscillating-slider wear test machines at temperatures up to 300{degrees}C. Without the silver films, the friction coefficients of Si{sub 3}N{sub 4}/Si{sub 3}N{sub 4} test pairs were 0.05 to 0.14, and the average wear rates of Si{sub 3}N{sub 4} pins were {approx}5 x 10{sup -8} mm{sup 3} N{sup -1}. The friction coefficients of Si{sub 3}N{sub 4}/cast iron test pairs ranged from 0.08 to 0.11, depending on test temperature. The average specific wear rates of cast iron ...

International Nuclear Information System (INIS)

For several decades, ceramic matrix composite have been attracted attention in advanced structural and tribological applications. Advanced structural ceramics are presently used in diverse tribological applications such as tips for ballpoint pens, precision instrument bearings and cutting tools inserts. Design and selection of ceramics for these applications require reliable data on the effects of temperature, load and environment on the tribological behavior of these ceramics. In the present work, #alpha#-sialon matrix composites reinforced with different amounts of #beta#-sialon fibers were produced with the aim of improving their toughness to increase the industrial applications. The wear properties of #alpha#-sialon matrix composites were evaluated by carried out wear tests using a pin-on-disk tribometer under dry conditions. The #alpha#-sialon matrix composites were manufactured by slip casting and sintered by uniaxial hot pressing. ...

International Nuclear Information System (INIS)

Textured silicon nitride (Si_3N_4) has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si_3N_4, with emphasis on the anisotropic and abnormal grain growth of #beta#-Si_3N_4, texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW) and templated grain growth (TGG). The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for #beta#-Si_3N_4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical models and experimental data, including the ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this investigation was to simulate a machining front from an abrasive waterjet and its movements in a ceramic material. Wear factors affecting the abrasive waterjet nozzle were also to be established. Therefore, a low inclination angle (9[degree]) was used between the nozzle and test sample, simulating a moving machine front. A standard nozzle with an inner diameter of 0.76 mm was used in the test, and it was placed close to the samples. The outer diameter of the abrasive nozzle was 9.5 mm. The high wear rate from abrasive waterjets makes it possible to machine hard ceramics-including dense alumina, titanium boride, silicon nitride, and composites-at high machining speeds.

Energy Technology Data Exchange (ETDEWEB)

Polyethylene (UHMWPE) wear in current knee prosthesis causes prosthesis loosening after no more than 15 years. In this work, a steady state one-dimensional lubrication model with non- Newtonian fluid, porous elastic layer on tibial component, ultra-filtration mechanism of fluid and some features of the surface roughness is studied through a numerical technique based on the Finite Element Method. The results show that the UHMWPE stiffness makes difficult the lubrication mechanism of the artificial joint and promotes abrasive and fatigue wear. Nevertheless, the use of compliant porous materials on the tibial component could reduce friction and wear. Moreover, the ultra-filtration mechanism promotes efficiency on the joint.

Energy Technology Data Exchange (ETDEWEB)

The purpose of the present study is to develop a new method for chemical state analysis by means of EPMA(Electron probe microanalyser). The measured X-ray intensity of Si-K{beta} characteristic X-ray spectra were read-out by a 16 bit microcomputer with a RS-232C interface. And using the curve fitting method the quantitative analysis of chemical compositions in a ternary compound that constituted of the same element has been established. The present method was applied to analyse of the friction and wear properties of Si-base ceramics sliding materials. It was found that the wear debris contains both the compositions of the sliding materials and SiO{sub 2}, and the SiO{sub 2} contents in wear debris was changed with relative humidity. The results clearly showed that the proposed method is very useful for determing the compositions in the ternary compound. (author).

Energy Technology Data Exchange (ETDEWEB)

Iron nickel chromium manganese silicon and iron chromium nickel manganese silicon molybdenum niobium alloys have a so-called duplex structure in a wide concentration range. This causes an excellent resistance to wear superior in the case of adhesive stress with optimized concentrations of manganese, silicon, molybdenum and niobium. The materials can be used for welded armouring structures wherever cobalt and boron-containing alloy systems are not permissible, e.g. in nuclear science. Within the framework of pre-investigations for manufacturing of filling wire electrodes, cast test pieces were set up with duplex structure, and their wear behavior was examined. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The Dynamic Transmission Electron Microscope (DTEM) is introduced as a novel tool for in situ processing of materials. Examples of various types of dynamic studies outline the advantages and differences of laser-based heating in the DTEM in comparison to conventional (resistive) heating in situ TEM methods. We demonstrate various unique capabilities of the drive laser, namely, in situ processing of nanoscale materials, rapid and high temperature phase transformations, and controlled thermal activation of materials. These experiments would otherwise be impossible without the use of the DTEM drive laser. Thus, the potential of the DTEM to as a new technique to process and characterize the growth of a myriad of micro and nanostructures is demonstrated.

Energy Technology Data Exchange (ETDEWEB)

In the present paper the tribological behavior of the coatings are discussed. Duplex coatings were applied on cold working steel 100Cr6. Samples were plasma nitrided at different thickness of plasma surface layers. TiN was deposited with a classic BALZERS PVD equipment and subsequent ion implantation. Ion implantation was provided with N{sup 5+} ions. The other samples were produced with IBAD technology in DANFYSIK chamber. Wear resistance and exchanges of friction coefficient were measured with on-line test using special designed tribology equipment. Following the tests, the wear zone morphology and characteristics of surface layer structure as well as important properties were investigated by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Scratch adhesion testing was performed using commercially available equipment. Energy dispersive X-ray analysis (EDAX) of the wear-scars on pins provided ...

Energy Technology Data Exchange (ETDEWEB)

In the second part of this paper the author concludes his examination of the application of thermoplastic materials and also considers alumina ceramics, cast basalt and glass, rubbers, resins and wear-resistant steels

Energy Technology Data Exchange (ETDEWEB)

A duplex surface treatment technique based on calorizing and plasma nitriding was developed to improve the wear and oxidation resistance of H13 steel at high temperatures. The effects of the relative thickness of the calorized layer to the depth of plasma nitriding on the wear and oxidation properties at temperatures up to 900 C were investigated in this work. High-temperature wear tests were performed at 500 C with dry conditions in open air using a ball-on-disk type tribotest machine. Isothermal oxidation tests were performed at 900 C for up to 100 h under controlled atmosphere. The results indicated that the specimens with a calorized layer as an intermediate phase between the surface duplex layer and the base metal showed higher wear and oxidation resistance than the specimens with a nitrided layer alone. During exposure to elevated temperatures, the aluminum in the calorized layer diffused to the ...

UK PubMed Central (United Kingdom)

Dogs are domestic reservoir hosts of Trypanosoma cruzi, the etiological agent of Chagas disease. We evaluated the effect of deltamethrin-treated dog collars (DTDCs) over time...Full Text Available

International Nuclear Information System (INIS)

The possibility of surface modification of high-speed steel cutting tool by means of vacuum-plasma treatment including ion nitriding in gas plasma followed by the deposition of wear resistant (Ti, Al)N coatings in metal-gas plasma of a vacuum arc discharge is studied. The regularities of nitrided layer formation and the structure of these layers under various operation conditions of cutting tool are investigated. Optimum conditions of vacuum-plasma treatment providing the best wear resistance of cutting are determined

International Nuclear Information System (INIS)

17-4PH stainless steel was modified by direct current (DC) plasma nitriding and titanium nitride film duplex treatment in this study. The microstructure, wear resistance and corrosion resistance were characterized by X-ray diffraction (XRD), pin-on-disk tribological test and polarization experiment. The results revealed that the DC plasma nitriding pretreatment was in favor of improving properties of titanium nitride film. The corrosion resistance and wear resistance of duplex treatment specimen was more superior to that of only coated titanium nitride film.

Energy Technology Data Exchange (ETDEWEB)

The refractory nature and high ductility of body centered cubic (bcc) phase tantalum makes it a suitable material for corrosion- and wear-resistant coatings on surfaces that are subjected to high stresses and harsh chemical and erosive environments. Sputter deposition can produce thick tantalum films but is prone to forming the brittle tetragonal beta phase of this material. Efforts aimed at forming thick bcc phase tantalum coatings in both flat plate and cylindrical geometries by high-rate triode sputtering methods are discussed. In addition to substrate temperature, the bcc-to-beta phase ratio in sputtered tantalum coatings is shown to be sensitive to other substrate surface effects.

Energy Technology Data Exchange (ETDEWEB)

In this study samples of AISI 4140 steel were pretreated by plasma nitriding and coated with two different physical vapour deposited coatings (TiN and TiAlN). A hardened AISI 4140 sample and a coated sample were also included in the investigation. To examine the influence of the nitrided zone on the performance of the coating-substrate composite, two different nitriding conditions - a conventional 25% N{sub 2} and an N{sub 2}-poor gas mixture - were used. The specimens were investigated with respect to their microhardness, surface roughness, scratch adhesion and dry sliding wear resistance. Wear tests in which the duplex-treated pins were mated to hardened ball bearing steel discs were performed in a pin-on-disc machine under dry sliding conditions. Metallography, scanning electron microscopy and profilometry were used to analyse the worn surfaces in order to determine the dominant friction and wear characteristics of the ...

Energy Technology Data Exchange (ETDEWEB)

The friction and wear properties of glass fiber reinforced composites of nylons (nylon 6, nylon 66 and nylon 46) with different crystallinities due to their molecular structures were investigated by sliding them with alumina ceramics and using a pin-on-disk friction machine. The friction coefficients of the glass fiber reinforced nylons in oil were lower and more stable than those in air from the initial stage of friction. The transfer of nylon matrix to adhere onto the alumina surface in air was so much greater than in oil that the alumina surface could not be recognized. Consequently, a different between the friction and wear properties in air and in oil was resulted. Reinforcement of nylons with glass fiber remarkably improved their friction properties in oil by its lubricating action, while the wears were rather high contrary to what was expected. This tendency was conspicuous for nylon 46 with high crystallinity. ...

International Nuclear Information System (INIS)

The ion nitriding treatment is a process widely used in steel alloys to improve the material's properties; such as surface hardness, resistance to wear, fatigue life and resistance to corrosion. But geometric changes in the components can produce during the nitriding process different effects on the behavior of the plasma, such as local variations in the electric field, an empty cathode effect, etc. These in turn can affect among other factors the local temperature and therefore the kinetics of the process, generating variations in the compound layer thicknesses and zone of diffusion, and micro-hardness profile. These heterogeneities limit the effectiveness of the plasma nitriding process, where control and duplication of the surface modification are most important. This work aims to study the effect of the geometry of the pieces treated with ionic nitriding, especially the effect of the orifices. An understanding of the operating mechanisms is ...

British Library Electronic Table of Contents (United Kingdom)

The thermal stability of nanoscale grains in cryomilled aluminum powders containing 1% diamantane was investigated. Diamantane is a diamondoid molecule consisting of 14 carbon atoms in a diamond cubic structure that is terminated by hydrogen atoms. The nanostructures of the resulting cryomilled powders were characterized using both transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The average grain size was found to be on the order of 22?nm, a value similar to that obtained for cryomilled Al without diamantane. To determine thermal stability, the powders were heated in an inert gas atmosphere at constant temperatures between 423 and 773?K (0.51T m to 0.83T m) for exposure times of up to 10?h. The average grain size for all powders containing diamantane was obse...

Energy Technology Data Exchange (ETDEWEB)

The relationship between microstructure and macro properties of different cementitious materials has been investigated. This study consists of the following tasks: using NMR and IR to better characterize the amorphous and poorly crystalline phases that occur in blended cements; characterizing the microstructure of the hydration products of modified Portland cement as a function of different percentages of pozzolan replacements by ESEM, SEM, and EDS; comparing the properties of blended cement pastes with a control group of normal Portland cements; and studying the engineering aspects of blended cement that are important for identifying and characterizing fundamental phenomena that are responsible for their durability. The overall influence of the nanoscale and microscale structure of blended and Portland cement on the properties of the resultant composite will be discussed.

British Library Electronic Table of Contents (United Kingdom)

The objective of materials research is the development of economical, safe and efficient synthesis routes that lead to the formation of a photocatalyst which is able to overcome performance problems related to particle size, crystallinity, or low surface area. Here, we report high-quality functional nanoparticles of calcium bismuth mixed oxide with 15nm nominal size corresponding to a specific surface area of 41m^2/g which were produced by single-step flame spray synthesis (FSS). The high temperature of the flame afforded creation of oxygen vacancies which were quantified by near edge X-ray absorption fine structure (NEXAFS) spectra. These two parameters, developed active surface area and created in the flame oxygen vacancies, allowed to enhance the photocatalytic activity of calcium bismu...

Energy Technology Data Exchange (ETDEWEB)

Nanoscale islands of Cu2O have been synthesized on single-crystal SrTiO3 (100) substrates using oxygen plasma-assisted molecular-beam epitaxy (OPA-MBE). Island growth location has been controlled by using an ex-situ Ga+ focused ion beam (FIB) to modify the growth surface in discrete locations prior to island synthesis. Analysis of Cu2O dot growth on unmodified substrate regions revealed an evolution of dot size and array density. Atomic force microscopy studies show that certain FIB substrate modification and MBE growth condition combinations lead to directed self-assembly of islands. Islands initially formed in the FIB-generated surface topography and filled those features before nucleating on neighboring unmodified surface regions.

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Nanoscale islands of Cu?O have been synthesized on single crystal SrTiO? (100) substrates using oxygen plasma assisted molecular beam epitaxy (MBE). Island growth location has been controlled by using an ex-situ Ga? focused ion beam (FIB) to modify the growth surface in discrete locations prior to island sythesis. The FIB modifications have generated surface topography with lateral dimensions of 150-200 nm. Ex-situ AFM study after island growth reveals that certain FIB substrate modification and MBE growth condition combinations lead to directed self-assembly of metal oxide islands at the edges of the FIB modified zones.

International Nuclear Information System (INIS)

There is currently great interest in combining focused ion beam (FIB) and scanning electron microscopy technologies for advanced studies of polymeric materials and biological microstructures, as well as for sophisticated nanoscale fabrication and prototyping. Irradiation of electrically insulating materials with a positive ion beam in high vacuum can lead to the accumulation of charge, causing deflection of the ion beam. The resultant image drift has significant consequences upon the accuracy and quality of FIB milling, imaging and chemical vapour deposition. A method is described for suppressing ion beam drift using a defocused, low-energy primary electron beam, leading to the derivation of a mathematical expression to correlate the ion and electron beam energies and currents with other parameters required for electrically stabilizing these challenging materials.

International Nuclear Information System (INIS)

Nowadays, diamond and the nitrogen-vacancy (NV) colour centres constitute the best solid-state system in view of quantum-computing applications. It has also been shown recently that single NV centres could be used as nanoscale magnetic sensors. Such applications require the creation of single NV centres with very high resolution and with a high efficiency. The nano-implanter at the university of Bochum provides low energy nitrogen ions which can be implanted through a hole pierced in the tip of an atomic force microscope. Ultrapure diamond samples have been implanted with spot sizes of 50nm and less. Stimulated Emission Depletion (STED) microscopy has been used to characterise and resolve the implanted spots.

Energy Technology Data Exchange (ETDEWEB)

Following comprehensive research nanomaterials or products which were either still in a re-search/development status or are already available in the marketplace were identified for the water and air sectors. Based on life cycle assessments for two case studies, it was checked how the potential benefits and impacts on the environment for nanotechnology products or processes compare with those for conventional solutions. The first case study deals with the solar treatment of water contami-nated with tetrachloroethylene, comparing nanoscale titanium dioxide (photo-catalysis) and a photo-Fenton process. The second case study on air filtration compares a passenger car cabin-air filter with nanofibres and a conventional filter. (orig.)

British Library Electronic Table of Contents (United Kingdom)

A ferritic steel with finely dispersed precipitates was investigated to reveal the fundamental strengthening mechanisms. The steel has a yield strength of 760MPa, approximately three times higher than that of conventional Ti-bearing high strength hot-rolled sheet steels, and its ultimate tensile strength reaches 850MPa with an elongation-to-failure value of 18%. Using energy dispersive X-ray spectroscopy (EDXS) and transmission electron microscope (TEM), fine carbides TiC with an average diameter of 10nm were observed in the ferrite matrix of the 0.08%Ti steel, and some cubic M23C6 precipitates were also observed at the grain boundaries and the interior of the grains. The finely dispersed TiC precipitates in the matrix provide matrix strengthening. The estimated magnitude of precipitation ...

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There are a number of characteristics exhibited by ceramic materials that may provide potential benefits for the reciprocating internal combustion engine. However, the brittle nature of these materials together with a variability in strength has created difficulties in applying ceramic materials to the engine environment. Although a wide range of physical properties is available from contemporary ceramic materials, a material offering consistently high strength has yet to be developed. For sliding-contact applications, desirable characteristics include good wear resistance, low friction, ability to join metals and good heat dissipation. Test results have shown that cam/follower components with cast iron cam sliding on a silicon nitride follower exhibit very low wear rates. The application of silicon carbide to face seals has also shown substantial reductions in both friction and wear when compared with conventional ...

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The dispersion of more than 20 vol pct submicrometer ceramic particles within a metallic matrix and the deposition of such a cermet to form a thick and tough coating presents problems. Most of the coating techniques have failed in attempting to homogeneously disperse very fine and hard particles in large amounts while avoiding their decomposition or reaction with the metal matrix during the deposition process. A simple and efficient method has been developed for producing ceramic-containing composite coatings. It consists in synthesizing cermet-based materials and in depositing them by a rapid solidification process, such as thermal spraying. Boride- and carbide-based materials have been successfully obtained by plasma spraying reactive powders comprising the basic reagents. These materials, with a microstructure of submicrometer ceramic particles dispersed in a metallic matrix, exhibit good wear-resistant properties (abrasion and sliding ...

International Nuclear Information System (INIS)

Nitrogen ion implantation improves the wear resistance of Ti-6Al-4V alloys by forming a hard TiN superficial passivation layer. However, the thickness of the layer formed by traditional ion implantation is typically 100-200 nm and may not be adequate for many industrial applications. We propose to use radio-frequency (RF) plasma nitriding and nitrogen plasma immersion ion implantation (PIII) to increase the layer thickness. By using a newly designed inductively coupled RF plasma source and applying a series of negative high voltage pulses to the Ti-6Al-4V samples. RF plasma nitriding and nitrogen PIII can be achieved. Our process yields a substantially thicker modified layer exhibiting more superior wear resistance characteristics, as demonstrated by data from micro-hardness testing, pin-on-disc wear testing, scanning electron microscopy (SEM), as well as Auger electron spectroscopy (AES). The performance of our newly ...

Energy Technology Data Exchange (ETDEWEB)

45{number_sign} steel, which has good mechanical strength and is relatively cheap, is a common constituent in industrial components, such as precision gears, piston columns of oil pumps, and so on. However, since the working environment of these industrial parts is sometimes quite harsh and unforgiving, they are vulnerable to wear and corrosion. Replacing 45{number_sign} steel with stainless or alloy steel increases the cost significant, and a better alternative is to improve its surface properties and lifetime using plasma immersion ion implantation (PIII). The authors have devised a variety of treatment processes using PIII, including radio-frequency (RF) plasma nitriding, RF plasma nitriding and nitrogen PIII, Ti deposition in conjunction with nitrogen PIII (IBED), as well as Cr deposition followed by nitrogen PIII (IBED). To assess the efficacy of the processes, the microhardness and mass loss due to wear were measured for both the ...

International Nuclear Information System (INIS)

There are a total of nine operational nuclear plants in Spain totalling 7.350 MWe. These units produced 54.265 x 106 KWh in 1990, 36% of the total generation in Spain. Seven of these plants are of the PWR type. The first plant in operation was Jose Cabrera (ZORITA) in 1968, one loop Westinghouse plant with a model 24 Steam Generator. Due to the design margin and careful operation of the Steam Generator of this plant its performance have been very good, with only 5% tubes plugged after 23 years of operation. This is one of the few units in the world that remains in phosphate chemistry. During the period 1981-1985 a total of four units, two in Almaraz and two in Asco entered in operation. These three loop s Westinghouse units use model D-3 preheater Steam Generators. The poor design and manufacture of the Steam Generators of these units have caused a large number of problems: mechanical (Preheater and AVB's vibration), denting, and primary and secondary stress corrosion cracking. As a ...

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In support of the efforts to apply ceramics to advanced heat engines, a study is being performed of the performance of ceramics at the ring/cylinder interface of advanced (low heat rejection) engines. The objective of the study, managed by the Oak Ridge National Laboratory, is to understand the basic mechanisms controlling the wear of ceramics and thereby identify means for applying ceramics effectively. Attempts to operate three different zirconias, silicon carbide, silicon nitride, and plasma-sprayed ceramic coatings without lubrication have not been successful because of excessive friction and high wear rates. Silicon carbide and silicon nitride perform well at ambient temperatures with fully formulated mineral oil lubrication, but are limited to temperatures of 500F because of the lack of suitable liquid lubricants for higher temperatures.

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This paper summarizes the results of a long-term research project by SKBV which aimed to find ways of increasing spiral chute capacity while minimizing particle degradation, and also to extend the life of chute linings. Spiral chutes have been redesigned in such a way that chute speeds are considerably slower. The most wear-resistant and economic material for the inlet area was found to be slabs of tempered alloy cast steel, and for normal chute sections, cast basalt plates. Vertical rom bunkers can now be lined with thin cladding sections of GRC. Staple pit spiral chutes have been considerably improved in respect to wear and abrasion by the use of toughened steel as the chute lining material. Several of the innovations developed during the course of the research project are in use in West German mines and some have also been introduced abroad. (In German)

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Interest in the tribological properties of plasma nitriding has increased substantially over the past years because plasma nitriding provides a high nitride depth and improved hard facing. The present study examines the tribological properties of AISI H11 plasma nitrided, hot-worked steel. Different nitriding temperatures and durations were considered. Characterization of the composite structures was investigated with wear tests, x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and microhardness tests. The depth profile of the nitrided zone was measured using the nuclear reaction analysis (NRA) technique. Plasma nitriding affected the microhardness, wear properties, and morphology considerably. Increase in process temperature increased the nitride zone depth.

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The refractory nature and high ductility of body centered cubic (bcc) phase tantalum makes it a suitable material for corrosion- and wear-resistant coatings on surfaces which are subjected to high stresses and harsh chemical and erosive environments. Sputter deposition can produce thick tantalum films but is prone to forming the brittle tetragonal beta phase of this material. Efforts aimed at forming thick bcc phase tantalum coatings in both flat plate and cylindrical geometries by high-rate triode sputtering methods are discussed. In addition to substrate temperature, the bcc-to-beta phase ratio in sputtered tantalum coatings is shown to be sensitive to other substrate surface effects.

Energy Technology Data Exchange (ETDEWEB)

TiB{sub 2} appears to be a promising material for the wear protection in various tribological systems, e.g. the diecasting of Al. This study focuses on the development of titanium boride coatings deposited by PACVD, a deposition method which is most suitable for the coating of substrates with complex shapes. All layers analysed are very smooth and exhibit a quasi-amorphous fracture surface. XRD and TEM analysis indicate a nanocrystalline structure with grain sizes in the order of 2 nm. The diffraction patterns can well be correlated to titanium diboride. WDS reveals an over stoichiometric B/Ti ratio. The layer hardness reaches the value of 33 GPa and the critical load in scratch tests rises to 35 N. Neither 100Cr6 nor Al as a counterpart in pin-on-disk tests leads to wear of the coating. (orig.)

British Library Electronic Table of Contents (United Kingdom)

The survival of acetabular components depends on several factors: wear, osteolysis and septic or aseptic loosening. Osteolysis seems to be the main cause for concern in cementless arthroplasties. Acetabular osteolysis results from particle debris and segmental unloading of acetabular bone by rigid sockets. We investigated a cementless elastic monoblock socket with regard to acetabular osteolysis and aseptic loosening in a cohort of young patients. We evaluated 158 hip arthroplasties with a minimum follow-up of ten?years (ten to 18) and a mean age of 42?years (18?50). The overall revision rate at 14?years was 80% with a 98% survival rate for aseptic loosening. The mean polyethylene wear rate was 0.11?mm/year. Progressive acetabular osteolysis was seen in 3% of patients evaluated. In conclus...

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Research at the interface between biomolecules and inorganic nanocrystals has resulted in a great number of new discoveries. In part this arises from the synergistic duality of the system: biomolecules may act as self-assembly agents for organizing inorganic nanocrystals into functional materials; alternatively, nanocrystals may act as microscopic or spectroscopic labels for elucidating the behavior of complex biomolecular systems. However, success in either of these functions relies heavily uponthe ability to control the conjugation and assembly processes.In the work presented here, we first design a branched DNA scaffold which allows hybridization of DNA-nanocrystal monoconjugates to form discrete assemblies. Importantly, the asymmetry of the branched scaffold allows the formation of asymmetric2assemblies of nanocrystals. In the context of a self-assembled device, this can be considered a step toward the ability to engineer functionally distinct inputs and outputs.Next we develop an ...

Energy Technology Data Exchange (ETDEWEB)

In support of the efforts to apply ceramics in advanced heat engines, a study was made of the sliding performance of ceramics at the ring/cylinder interface of low heat rejection engines. The objective was to understand the basic mechanisms controlling the wear of candidate ceramics and thereby identify means for applying these ceramics effectively. Attempts to operate three different zirconias, silicon carbide, silicon nitride, and several plasma-sprayed ceramic coatings without lubrication were unsuccessful because of high friction and high wear rates. Experiments using a polyalphaolefin lubricant at temperatures to 260 C identified several combinations having wear rates in the general range likely to be acceptable for engines. Plasma-sprayed coatings of chromium oxide and hypersonic powder flame sprayed coatings of cobalt-bonded tungsten carbide performed particularly well as ring coatings. Similar performance was ...

Energy Technology Data Exchange (ETDEWEB)

A hydrocarbon composition having a major portion of a hydrocarbon preferably a lubricating oil such as mineral oil and at least a friction-reducing amount usually 0.01 to 10 weight percent of an amine or amine derivative of a hydrocarbon-soluble polymerized fatty acid e.g. a dimeramine derived from a dicarboxylic acid containing at least 12 carbon atoms such as 9(10)-carboxy stearic acid has improved antifriction and flue economy properties.

Science.gov (United States)

These are some interesting sites that will help you to understand networking and how it can benefit you. These sites contain sound so you may want to wear headphones if you are in a classroom. Learn how the internet began and the basics of the www. Learn why a network is useful. Jans network contains the important concepts of networking, Work through section 7 to learn about different types of connections, transmissions, media, and configurations. Then take the quiz at the end to see how ...

International Nuclear Information System (INIS)

In order to investigate the role of amorphous SiO2 particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO2 particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO2 was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO2 particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of ?-phase and amorphous nano-SiO2 particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO2 particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion resistance of composite alloying layer was investigated by an electrochemical method in 3.5%NaCl solution. Compared with single alloying layer, the ...

Energy Technology Data Exchange (ETDEWEB)

The wear behaviour of metallic material is influenced by the friction force, which in turn, is governed by the hardness and oxidation kinetics of the mating surface. In view of this, present investigation is undertaken to find the influence of mating surface on the high temperature wear of 253 MA alloy. This alloy is developed for high temperature application. In this work 253 MA alloy is made to slide against two different types of counter face material, namely 100Cr6 steel and PM 1000 alloy, at five different temperatures. 100Cr6 steel gets soften with increase of temperature whereas PM 1000 alloy retains its strength even at high temperature. The friction coefficient and the thickness loss of 253 MA alloy is measured and compared against both variety of mating surfaces as function of temperatures. The morphology of the worn surfaces and the transverse section of the worn surfaces are examined under scanning electron microscope (SEM) to ...

Energy Technology Data Exchange (ETDEWEB)

Nanoimprinting is a fast-growing technique for nanoscale patterning. One of the remaining issues in nanoimprinting is the removal of the residual layer after nanoimprinting. Traditionally the residual layer is removed by an oxygen reactive-ion etching (RIE) step. The need for a vacuum environment and dedicated equipment in this step lowers the throughput and increases the cost of the nanoimprinting process. It also prevents the possibility of patterning isolated functional polymers because oxygen RIE destroys the functional materials. In this work, novel nanoimprinting schemes are developed to nondestructively remove the residual layer in thermal nanoimprinting by solvent developing and dewetting. Combined with a transfer-bonding technique, three-dimensional polymer scaffolds are achieved. The techniques developed here eliminate the RIE step in thermal nanoimprinting and are compatible with roller nanoimprinting for large-scale patterning of polymer micro- or ...

Science.gov (United States)

We have investigated the nanotexture and crystallographic orientation of aragonite in a coral skeleton using synchrotron-based scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM). Polarization-dependent STXM imaging at 40-nm spatial resolution was used to obtain an orientation map of the c-axis of aragonite on a focused ion beam milled ultrathin section of a Porites coral. This imaging showed that one of the basic units of coral skeletons, referred to as the center of calcification (COC), consists of a cluster of 100-nm aragonite globules crystallographically aligned over several micrometers with a fan-like distribution and with the properties of single crystals at the mesoscale. The remainder of the skeleton consists of aragonite single-crystal fibers in crystallographic continuity with the nanoglobules comprising the COC. Our observation provides information on the nm-scale processes that led to biomineral formation in this sample. Importantly, ...

Energy Technology Data Exchange (ETDEWEB)

Abstract: We report for the selective-area chemical synthesis of semiconductor single-crystal organic nanowires of silver-tetracyanoquinodimethane (Ag-TCNQ). Straight and smooth Ag-TCNQ nanowires can be produced and patterned on micrometer and nanometer scale on silicon substrates covered with a thin layer of Ag film through the reaction of TCNQ and Ag in a simple gas-solid chemical reaction process. Ag-TCNQ nanowires are characterized by UV-vis, IR and Raman spectroscopy, respectively. The Ag-TCNQ nanowires grows preferentially along the [100] direction of strong - stacking of Ag-TCNQ molecules. Nanodevices based on these nanowires are fabricated using focus ion beam (FIB) technique. Electrical properties are characterized and I-V hysteresis is observed, which shows memory effect with electrical switching of three orders on-off ratio. These nanowires could be potential for use in optical storage, ultrahigh-density nanoscale memory and logic devices.

International Nuclear Information System (INIS)

Liquid metal ion sources (LMISs) with Ga as ion species are widely used in focused ion beam (FIB) technology for micromachining and surface treatment on the sub-micron and nano-scale. Key features of a LMIS for investigating mechanical properties and 3D-microfabrication of materials are long life-time, high brightness, stable ion current and a highly effective milling ability for the material to be modified. In order to increase the material removal rate, heavier ions than Ga and their clusters should be applied. Bismuth (Bi) is the heaviest, non-radio-active element in the periodic table, is non-toxic and exhibits a low melting point. We have thus produced a long-life (about 1000 h) Bi LMIS with a good beam performance, applicable in any FIB system. Since Bi is the only element in this source, it is not necessary to separate it from other ions by a mass filter. Investigation of the sputtering rate of NiTi shape memory alloys using Ga and Bi LMIS showed that, for ...

International Nuclear Information System (INIS)

Research highlights: #-># Morphological and chemical characterization at atomic scale of porous alumina layers anodised in ordered regimes. #-># Characterization based on the use of FEG-SEM, STEM-HAADF, STEM-EELS and STEM-X-EDS. #-># Nanoscale distribution of P-, C- and S-bearing species in the pore wall. - Abstract: Ordered porous alumina layers prepared by two-step anodising in phosphoric, oxalic and sulphuric acids have been characterized at sub-nanometer scale using electron microscopy techniques. FEG-SEM and STEM-HAADF images allowed estimating the pore size, cell wall and pore wall thicknesses of the layers. Nanoanalytical characterization has been performed by STEM-EELS and STEM-X-EDS. Detailed features of the spatial distribution of anions in the pore wall of the films have been obtained. Maximum concentration of P-species occurs, approximately, at the middle of the pore wall; adjacent to the pore for C-species, whereas the distribution of ...

International Nuclear Information System (INIS)

Small-angle X-ray scattering method recognised to be very useful in the studies of structural problems of materials in homogeneous in nanoscale. Studies by small-angle X-ray scattering on the Al-Ag alloys are presented. The size distributions of spherical Guinier-Person zones were calculated using Vonk's and Glatter's methods. Small-angle X-ray scattering studies were performed on Al-5.0 at.%Ag alloy containing Guinier-Preson zones in the #eta#-state. For this alloy one can assume that scattering particles are of spherical shape, have uniform electron density and scatter independently. Moreover, the size distributions were calculated for Al-1.6 at.%Ag alloy containing Guinier-Preston zones in #epsilon#-state (scattering particles with not uniform electron density). Both, Vonk's and Glatter's, methods gave similar size distributions. Profiles of size distributions for Guinier-Preston zones in #epsilon#-state are more complex in comparison to Guinier-Preston zones in ...

Energy Technology Data Exchange (ETDEWEB)

Neutron diffraction was used to monitor elastic strains during in situ tension testing of a directionally solidified (DS) superalloy at 900 deg. C. Changes in misfit and thermal expansion coefficients of individual phases were obtained. In the {gamma} phase, it is demonstrated that elastic strains saturate at 350 MPa, which is well below the yield strength of the alloy. This is interpreted as the onset of dislocation glide through less stressed vertical channels. The critical resolved shear stress (CRSS) of {gamma} is found to be 143 {+-} 11 MPa, in agreement with a calculated CRSS that is dominated by Orowan bowing of dislocations through nanoscale-wide {gamma} channels. This provides confirmation of Orowan bowing in plasticity/creep of the {gamma} phase. Implications of CRSS and misfit in a 'threshold stress' for creep and rafting are discussed. The CRSS of {gamma}' is found to be consistent with pairwise penetration of dislocations ...

International Nuclear Information System (INIS)

We developed a new systematic calibration procedure which was applied to the prediction of the diffusivity, the segregation, and transient enhanced diffusion (TED) of an indium impurity. The TED of the indium impurity was studied using four different experimental conditions. Although indium is susceptible to TED, rapid thermal annealing (RTA) is effective in suppressing the TED effect and maintaining a steep retrograde profile. Like boron impurities, the indium shows significant oxidation-enhanced diffusion in silicon and has segregation coefficients much less than 1 at the Si/SiO_2 interface. In contrast to boron, the segregation coefficient of indium decreases as the temperature increases. The accuracy of the proposed procedure was validated by using secondary ion mass spectrometry (SIMS) data and by using the 0.13-#mu#m device characteristics, such as V_t_h and I_d_s_a_t, for which the differences between simulation and experiment less than 5 %.

Energy Technology Data Exchange (ETDEWEB)

In addition to ceramics, alloys such as tool steel and nickel- and iron-based superalloys are being considered for high temperature applications such as missile bearings and low heat rejection engines. Studies were made to lubricate a nickel-based superalloy at 500{degrees}C, by using a vaporized aryl phosphate ester, at a concentration of 0.1% in air. From deposition and wear studies it was found that it was impossible to form a good polymeric coating on the superalloy surface. Energy dispersive X-ray analyzer (EDXA) analysis showed that this was due to minute quantities of aluminum in the alloy segregating to the surface, upon being heated to 500{degrees}C, forming a passive oxide coating. It was necessary to activate the surface, in order to lubricate the material successfully. A method of activation by electrodepositing the surface with a layer of iron oxide was developed. Once activated, a good lubricous polymer was formed on the superalloy surface. Tests ...

International Nuclear Information System (INIS)

The microstructure, microhardness, corrosion, and wear resistance of d.c.-plated Ni electrodeposits prepared from different types of electrolysing Watts-type baths, without or with organic compounds, ceramic powder - SiC and polymer - polytetrafluoroethylene (PTFE), on Cu substrate, which was subsequently removed from the deposits, were investigated. With the change of the type of bath, the deposit grain size was found to decrease markedly, e.g. deposits with an average grain size of about 50 nm could be produced from the bath containing 45 g/dm"3 Ni"2"+ ions, 5 g/dm"3 SiC, and 20 g/dm"3 PTFE. The surface morphology on the bath side of the electrode-posited Ni or Ni-SiC-PTFE foils was characteristic of the type of bath, and its roughness correlated well with the observed grain size. Microhardness and wear resistance increased with decreasing grain size, as expected. On discussing the factors controlling deposit grain size, it is concluded that ...

Energy Technology Data Exchange (ETDEWEB)

A radio frequency sputtering apparatus with a pair of targets has been developed for depositing a film of uniform thickness onto a complex-geometric specimen such as the retainer of a ball bearing. The deposition characteristics of the apparatus were compared with those of the conventional sputtering apparatus. Lubrication properties of MoS/sub 2/ films made by these devices were also compared under a variety of conditions. Finally, friction and wear of MoS/sub 2/ films applied to angular-contact type ball bearings of 20 mm bore were studied in air, nitrogen and vacuo. The two-target sputtering has an advantage mentioned above. However, the films deposited by the method exhibited a rather short wear life because of the temperature rise of the substrate during ion bombardment and during the sputtering process. This temperature dependence was observed in films on those substrates that had been heated with a built-in heater during sputtering. The ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study is to develop the radioisotope tracer technology, which can be used in solving industrial and environmental problems and to build a strong tracer group to support the local industries. In relation to the tracer technology in 1999, experiments to estimate the efficiencies of a sludge digester of a waste water treatment plant and a submerged biological reactor of a dye industry were conducted. As a result, the tracer technology for optimization of facilities related to wastewater treatment has been developed and is believed to contribute to improve their operation efficiency. The quantification of the experimental result was attempted to improve the confidence of tracer technology by ECRIN program which basically uses the MCNP simulation principle. Using thin layer activation technique, wear of tappet shim was estimated. Thin layer surface of a tappet shim was irradiated by proton beam and the correlation between the measured activity loss ...

Energy Technology Data Exchange (ETDEWEB)

This research and development is intended to structure a network centering around a center having systematized high-level maintenance technology, by utilizing the technological infrastructure having been built in local areas, together with element technologies possessed by national and private research institutes, universities and colleges. It is also purposed to establish a new industrial system for maintenance to realize high reliability, high operation rate and low cost in plants in certain areas. The present fiscal year had the following achievements: research and development of a maintenance system, a maintenance model, a maintenance vehicle, damage estimating technology for stationary parts such as piping, an anomaly diagnostic system using acoustic emission, an anomaly diagnostic system using wear particles in lubricant, an anti-wear material using surface modification, a lubrication control system, and an anomaly diagnostic system using ...

International Nuclear Information System (INIS)

Advanced structural ceramics are presently used in several tribological applications, such as precision instrument bearings, automotive engine parts and cutting tools inserts. Design and selection of advanced ceramics for these applications require reliable data on the effects of temperature, load and environment on the tribological behaviour of these materials. In the present work, the friction and wear behaviour of colloidally processed and pressureless sintered sialon ceramics with phase (#alpha#) have been studied, aiming at increasing #alpha#-sialon in industrial applications as cutting tools. The friction and wear behaviour of sialon ceramics against steel DIN-Ck45K were investigated using a pin-on-disk tribometer under dry sliding conditions at room temperature, in order to eliminate the contribution of lubricant. The experiments were performed with a constant sliding velocity of 0.5 m/s and a contact stress of 2.85 MPa for 2000 m of ...

Science.gov (United States)

... Accession Number : ADD457408. Title : FIELD CORROSION TESTS FOR COMPARISON OF CORROSIVITY IN JAPAN AND CHINA. ...

Energy Technology Data Exchange (ETDEWEB)

Twenty years after its building, the tertiary sector of La Defense district near Paris has been rehabilitated. The main reason is not only the age and wear of materials but the heating costs, the fire protection regulations, the search for a better air quality and air renewing with less dusts, smells and noise and a controlled moisture. This paper describes first the original installation of the Monge CB 6 office building and then the renovated installation: the central hot and cold air-treatment plant, the variable flow ventilation system, the air extraction and supply system threw the roofs and the pressure and thermal regulation of the installation. (J.S.)

Energy Technology Data Exchange (ETDEWEB)

Ammonia gas (NH{sub 3}) has been used as a nitrogen source for plasma source ion implantation processing of electroplated chromium. No evidence was found of increased hydrogen concentrations in the bulk material, implying that ammonia can be used without risking hydrogen embrittlement. The retained nitrogen dose of 2.1 {times} 10{sup 17} N-at/cm{sup 2} is sufficient to increase the surface hardness of electroplated Cr by 24% and decrease the wear rate by a factor of 4.

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Silicon nitride hybrid ball bearings used in high temperature applications undergo mechanical and environmental degradation. To study the surface chemistry of silicon nitride, a CAChe{trademark} Worksystem* has been used to generate the clusters and corresponding transmission vibrational spectra of silicon nitride. In the present study, the effect of surface conditions on the surface chemistry and wear degradation of silicon nitride was evaluated. Infrared reflection spectroscopy (IRRS) used to determine molecular orientations shows a difference in reflectance spectra for fractured and as-received.

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The microstructure and mechanical properties of a specimen HIPped at 1100 C under 60 ksi were examined. The examinations indicated that the proper HIPping temperature for this material should be higher than 1100 C. New recipe of monolithic material was developed and presented better extrusion homogeneity and less binder removal defects. However, cracking still occurred in specimens although very slow heating rate of 0.25 C/min for binder burnout was used.

Energy Technology Data Exchange (ETDEWEB)

Physico-chemical characterizations performed on samples of 100Cr6 steel implanted both with boron and nitrogen revealed the formation of boron nitride along with the following new phases: Fe{sub 1-x}(B, N), Fe{sub 2-x}(B, N) and Fe{sub 3-x}(B, N). A thorough analysis of boron NITRIDE (5BN) indicates that a low ion current density (3 {mu}A.cm{sup -2}) in the case of the boron plus nitrogen sequence favours the formation of sp{sup 2} bonds (hexagonal-BN) while a higher ion current density (6{mu}A.cm{sup -2}) promotes sp{sup 3} bonds (cubic-BN) in the opposite sequence. Tribological tests carried out on these samples revealed that nitrogen and boron implantations do not lead to any significant improvement of friction and wear at variance with the results obtained by others authors. However, on a set samples accidentally contaminated with carbon during implantation, we noticed a considerable improvement of these tribological parameters. As this pollution is commonly ...

Energy Technology Data Exchange (ETDEWEB)

The bibliography contains citations concerning the properties, industrial uses and federal regulation of asbestos. The references explore advantages and disadvantages associated with use of industrial robots in areas containing high concentrations of asbestos dust, the use of water as a cutting tool to control the generation of asbestos dust, and governmental policies and attitudes relative to the health and welfare of workers subjected to asbestos. Thermal insulation properties, wear characteristics, high temperature capabilities, use as a reinforcement in composite materials, and asbestos substitutes are included. (Contains a minimum of 69 citations and includes a subject term index and title list.)

International Nuclear Information System (INIS)

Plasma immersion ion implantation (PIII) is an effective materials modification and synthesis technique but has seldom been applied to ceramic materials due to the high electrical resistance that reduces the ion bombardment energy and sometimes causes serious electrical arcing in the instrument. Even in cases where PIII is applicable, the surface properties of the implanted insulating materials can be seriously affected due to the low ion energy and materials damage from electrical arcing. In order to enhance the surface and mechanical properties such as wear resistance of ceramic materials used in many industrial applications, surface modification is needed. In this work, we conduct carbon implantation into sintered #alpha#-SiC (silicon carbides that are widely used in vacuum ceramic bearings) using mesh-assisted plasma immersion ion implantation to enhance the surface properties. The use of a conducting grid is necessitated by the high electrical resistance that ...

UK PubMed Central (United Kingdom)

We consider the problem of minimal (multiplicative) complexity of polynomial multiplication and multiplication in finite extensions of fields. For infinite fields minimal complexities are known [Winograd,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

KoreaScience (Korea)

Full Text Available

International Nuclear Information System (INIS)

The authors present a summary of the present state of the quantum field theory of tachyons. (W.D.L.).

CERN Document Server

Metals and alloys : atmospheric corrosion testing : General requirements for field tests

CERN Document Server

An introduction to recent developments in several active topics at the interface between algebra, geometry, topology and quantum field theory

Science.gov (United States)

A bright field scanning transmission electron microscope (STEM) micrograph showing a Wassonite grain in dark contrast. ...

Energy Technology Data Exchange (ETDEWEB)

Tribological performance of alumina and silicon carbide ceramics as well as of the hardened steel 100Cr6 for reference was studied during reciprocating sliding and cavitation erosion in isooctane as substitute of gasoline and in distilled water. It was the aim to characterize effects of surface finish of the specimens and the liquid media on friction, resistance to sliding wear and cavitation erosion. Sliding wear tests were run on the self-mated ceramics and ceramic/steel pairs under conditions of boundary lubrication using a laboratory tribometer with cylinder-on-plate geometry. Vibratory cavitation erosion tests were conducted according to ASTM G 32-92. High initial surface roughness of coarse ground specimens led to a distinct running-in period during sliding contact with a transition from high to low values of friction coefficient and wear intensity. Incubation time was reduced with increasing surface roughness in the ...

British Library Electronic Table of Contents (United Kingdom)

The immune system modulates many key biological processes in humans. However, the exact role of the immune system in particle-associated periprosthetic osteolysis is controversial. Human tissue retrieval studies, in vivo and in vitro experiments suggest that the immune response to polymer particles is non-specific and macrophage-mediated. Lymphocytes may modulate this response. However direct lymphocyte activation by polymer particle-protein complexes seems unlikely. However, metallic byproducts may complex with serum proteins and lead to a Type IV, lymphocyte-mediated immune reaction. In predisposed individuals, this reaction may rarely lead to persistent painful joint effusions, necessitating debridement and excision of the bearing surfaces of the prosthesis. In these patients, retrieved...

International Nuclear Information System (INIS)

The Steam Generator (SG) tubing degradation caused by corrosion and other age-related mechanisms continues to be a significant safety and cost concern for many Nuclear Power Plants (NPP). The understanding of the steam generator ageing mechanisms is the key to effective management of steam generator ageing and consists of the knowledge of steam generator materials and these one properties, stressors and operating conditions, like degradation sites and wear mechanisms. The principal types of corrosion are presented which can occur in CANDU steam generator. There are also presented the operation conditions, the specifications referring to the water chemistry and the construction materials of Steam Generator, the factors that have a great influence on the corrosion behaviour during the whole exploitation period of this equipment. (R.P.)

Energy Technology Data Exchange (ETDEWEB)

Stainless steels can be nitrided at temperatures {<=}400 C to increase their hardness and wear resistance without a decreasing of their excellent corrosion resistance. Structure and properties of the surface layers produced by plasma nitriding and plasma immersion ion implantation in this temperature range were tested. There are negligible differences in the structure of the produced surface layers in spite of different interaction principles of the used technologies. However there are clear differences between the case of different steels. The case of ferritic chromium steels mainly consists of {epsilon}-nitride. Whereas the cases of austenitic and ferritic austenitic steels are characterized by expanded austenite. The corrosion resistance of the steels is reduced by nitriding only, if evident CrN-formation occurs. (orig.) 11 refs.

International Nuclear Information System (INIS)

Until a decade ago, only the differential bobbin type eddy current probe was considered necessary for reliable heat exchanger tube inspection. The introduction of different tube materials, manufacturing processes and a variety of service induced failures has greatly increased the demands of eddy current testing. Optimized probe designs enhanced by improved instrumentation can help satisfy some of these demands. Some of the more difficult inspection problems are detection of circumferential cracks, fretting wear under non-ferromagnetic support plates and shallow internal defects. Reliable detection and sizing of such defects is often made more difficult by the fact they frequently occur in defect prone regions such as under tubesheets or support plates and in transition regions of finned tubes. Probe designs effective in overcoming these difficulties exist. This paper describes a number of such probes and their performance.

British Library Electronic Table of Contents (United Kingdom)

Mobile offshore drilling rigs are used to drill, complete and workover wellbores in marine environments. The fleet that exists today consists of a wide variety of vessels built to various specifications over the past three decades, and because they operate in harsh, corrosive environments, they wear out structurally and require periodic maintenance. Rig designs have evolved with changes in operating requirements and new technology and rigs are frequently modified and upgraded, depending upon market conditions, operator preferences and other factors. The construction and replacement costs of offshore rigs are often used for management planning, financial valuation and insurance analysis, and because of the wide variety of designs, specifications and upgrades, cost estimates vary widely. In ...

International Nuclear Information System (INIS)

A ternary nickel-base alloy Ni-W-B has been developed for surface corrosion and wear resistance to replace chromium plating, which uses environmentally hazardous solutions. The deposition conditions used an alkaline bath and insoluble anodes. The as-deposited alloy typically contains 40 wt% W and 1 wt% B and has an amorphous or partially amorphous structure. These deposits compare favorably with hexavalent chromium deposits in throwing power, color uniformity, and reflectivity. The corrosion resistance of Ni-W-B alloy was compared with hexavalent chromium and electroless nickel deposits in a variety of acids, including hydrochloric, sulfuric, fluoroboric, and phosphoric. In all cases, best results were obtained with the Ni-W-B deposits.

British Library Electronic Table of Contents (United Kingdom)

The carbon fibers (CF) were pre-treated in two different ways: no pre-treatment, and activation in HNO3 plus application of toluene-2,4-diisocyanate (TDI). Carbon fibers have been introduced into polyurethane (PU) composite coatings. The tribological behaviors of the polyurethane composite coating filled with CF or TDI-modified CF (TDI-CF) were studied using a ring-on-block wear tester under dry sliding, and the worn surfaces of the filled PU coatings and transfer films formed on the surface of the counterpart ring sliding against the PU coating were investigated by SEM and optical microscope (OM), respectively. Owing to the effective improvement of the interfacial adhesion between the CF and polyurethane matrix, compared with the cases of untreated CF, the employment of low content TDI-CF...

British Library Electronic Table of Contents (United Kingdom)

The determination of residual stress (RS) in case-hardened steel gear truck synchronisers coated with thermal sprayed molybdenum was carried out using neutron and synchrotron X-ray diffraction. Two samples with different coating thicknesses (about 120 ?m and 1.4 mm) and different steel substrates (16MnCr5 and SAE4140, respectively) were investigated. Microanalysis revealed substantial porosity in both samples and some debonding was observed between the thin coating and the substrate. The bulk hardness of the SAE 4140 proved to be much higher than the 16MnCr5 and the surface case-hardening increased it by a further 20%. The full three-dimensional stress depth-profile was determined by neutron diffraction (ND) in both the coatings and the substrates, while synchrotron radiation allowed a dep...

Energy Technology Data Exchange (ETDEWEB)

A combination of erosion and corrosion at the Victoria Junction coal preparation plant in Sydney, Nova Scotia was causing serious problems. Schedule 80 mild steel pipes were starting to fail as well as some quarter-inch steel plates in the lauders and chutes. Some corrosion tests were carried out and the high chloride level in the process water was felt to be the single most important contribution to the corrosion problem. Cast basalt was selected as a solution to the pipe wear problem. Three different types of abrasion/corrosion-resistant tiling - basalt tiles, kalceram tiles and ceramic tiles were well suited to the chloride conditions at this plant.

International Nuclear Information System (INIS)

Composite nitrides (such as BN, TiN) are widely used in various industrial applications because of their extreme wear and corrosion resistance, thermal and electrical properties. in order to obtain composite materials with these optimal properties, it is important to elucidate whether any chemical reactions occur at nitride/metal interfaces, e.g., those involving BN-Ti/TiN. Materials of interest include the deposition by PVD of Ti and TiN on BN substrates. Some of these systems were then subjected to varying degrees of physical and thermal alteration. Detailed X-ray photoelectron spectroscopy (XPS) has therefore been rendered of these interfaces using cross-sectional display and sputter etching. Resulting structural and morphological features have been investigated with transmission electron microscopy (TEM) and X-ray diffraction (XRD). Diffusion of the nitridation, oxynitride formation and interfacial growth are of general interest.

International Nuclear Information System (INIS)

Fibre-reinforced-polymer-composite material has been suggested as a bearing material to overcome tribological problems witnessed during the testing of Ram assembly of the 540 MWe fuelling machine at RTD. After successful trials at B-Ram the composite material has been adapted for B-RAM, C-Ram and RDB head at fuelling machines being tested at RTD, Hall 7 and at Tarapur. Laboratory evaluations were also carried out at Tribology Lab RTD to study effect of radiation on the composite. Paper deals with the various aspects of life prediction of this material in term of wear and radiation damage. (author)

International Nuclear Information System (INIS)

Full text: It was recently-established for hexagonal barium ferrite-industrially important magnetically hard material that refinement of the crystallite dimensions into the nanoscale regime, typically #<=# 10 nm, leads after heat treatment at temperatures 800-1000 deg C to significant coercivity increase of up to 6.5 kOe (#approx#3-4 times) with saturation magnetisation values of 50-55 emu/g (#approx#95% of bulk at room temperature). High-energy mechanochemical processing has been applied to prepare nanostructural (nanocrystalline-amorphous) composites. High resolution electron microscopy studies reveal that the enhancement of the final magnetic properties was due to formation of magnetically noninteracting #approx#l,#mu#m Ba-ferrite particles with 5-10 nm amorphous surface layer - depending on annealing parameters. Similar situation was established also for ball milled strontium ferrite (SrFe_1_2O_1_9) powders where short annealing 4 h at 1000 deg C produced ...

Energy Technology Data Exchange (ETDEWEB)

Individual nanoscale building blocks exhibit a wide range of size-dependent properties, since their size can be tuned over known characteristic length scales of bulk materials. In the last several years, the possibility of combining different materials in the form of two and three component nanoparticles (NPs) has been extensively explored. Also multi-component materials can be obtained via self-assembly of NPs from their binary colloidal mixtures. These new nanocrystal solids may possess tunable collective properties that originate from interactions between size and composition controlled building blocks. Exchange coupling between neighboring NPs of magnetically soft and hard materials enhances the magnetic energy product of the nanocomposite material. Randomly mixed solids of small and large semiconducting CdSe NPs revealed enhancement of photoluminescence intensity of large semiconductor particles accompanied by quenching of photoluminescence of the small ...

International Nuclear Information System (INIS)

We have investigated the nanocrystalline microstructure and the hard magnetic properties of Sm(Co_0_._7_2_5Fe_0_._1Cu_0_._1_2Zr_0_._0_4B_0_._0_1_5)_7_._4 melt-spun ribbons. The coercivity (H_c) of the as-spun ribbons increased with the wheel surface speed from 2.8kOe for 10m/s to 14.5kOe for 40m/s. The post-annealing of the melt-spun ribbons from 700 to 900 deg. C for 10min did not lead to a substantial increase of H_c. However, after isothermal aging at 820 deg. C and subsequent slow cooling (0.5 deg. C/min) to 120 deg. C, H_c increased from 2.8 to 10.9kOe for 10m/s, while it decreased from 14.5 to 13.5kOe for 40m/s ribbons. The grain size of the melt-spun ribbon reduced with structural transformation from 2:17H (Th_2Ni_1_7-hexagonal type) to 1:7H (TbCu_7-hexagonal type) as the wheel surface speed was increased. Three-dimensional atom probe analysis showed a boron enriched precipitate at the grain boundaries in the as-spun ribbons, which acts as the grain growth inhibitor causing the ...

International Nuclear Information System (INIS)

We review the current status of Andreev reflection spectroscopy on the heavy fermions, mostly focusing on the case of CeCoIn5, a heavy-fermion superconductor with a critical temperature of 2.3 K. This is a well-established technique to investigate superconducting order parameters via measurements of the differential conductance from nanoscale metallic junctions. Andreev reflection is clearly observed in CeCoIn5 as in other heavy-fermion superconductors. Considering the large mismatch in Fermi velocities, this observation seemingly appears to disagree with the Blonder-Tinkham-Klapwijk (BTK) theory. The measured Andreev signal is highly reduced to the order of maximum ?13% compared to the theoretically predicted value (100%). The background conductance exhibits a systematic evolution in its asymmetry over a wide temperature range from above the heavy-fermion coherence temperature down to well below the superconducting transition temperature. Analysis of the ...

International Nuclear Information System (INIS)

With the deposition of PVD hard coatings on the tools applied in machining operations it is possible to achieve significant improvements in the performance and quality of the machining processes. Depending on the machined material and the operating principle, e.g. turning, milling or drilling, not only different machining parameters but also different coating materials are necessary. In interrupted cut machining of tempered steel, for example, the life time of Ti-C-N coated inserts is several times greater than the Ti-C-N coated ones. This is a result of the favourable thermophysical and tribological properties of Ti-N-C. The potential for tool protection by CrN coatings is a result of the high ductility and low internal stress of this coating materials. CrN films can be deposited with greater film thickness, still maintaining very good adhesion. This paper presents the development of new arc PVD coatings in the system Cr-C-N. Owing to the carbon content in the coating an increased ...

Energy Technology Data Exchange (ETDEWEB)

Diamond-like carbon thin films for tribological applications were deposited by d.c.-magnetron sputtering of a graphite target in a pure argon atmosphere or in a reactive hydrogen or methane atmosphere at pressures between 0.1 and 1 Pa in a graded constitution to improve adhesion and reduce residual stress. The temperature of the metallic, carbon- and ceramic-like substrates was below 100 C. The mechanical, thermal, electronic and optical properties of the carbon thin films show a significant dependence on the ion energy. Below 220 eV, strongly adherent black conductive films with hardness values up to 2000 HV0.05 were obtained. Hard and superhard diamond-like carbon thin films were deposited in an energy range between 220 and 370 eV with hardness values up to 4000 HV0.05. They are insulating, optically transparent and show a high degree of hardness combined with high compressive stress in the order of 4 GPa as well as a low adhesion, which means that the critical loads of failure are ...

Energy Technology Data Exchange (ETDEWEB)

When materials such as metal are into the secondary side of steam generator, they, so called foreign objects, may have influences on the integrity of the steam generator tubes. They cause the tube wear due to the relative motion between the tubes and foreign objects and the tube impact due to flow. The best way to avoid the effects is to remove all the foreign objects. However, it is not easy to remove the foreign materials thoroughly due to their condition such as the location. If the locations of the foreign materials are in the middle of tube bundle and the tube arrangement of the steam generator is the triangle type, the equipment such as FOSAR(Foreign Object Search and Retrieval) can not reach their locations. If the foreign materials stick together with the tubes or tube sheet, they can not be removed. In the case of operating the steam generator with the foreign materials, the licensee must prove that the materials do not affect the tube integrity and do not ...

CERN Document Server

We calculate the quarkonium dissociation rate in the P and CP-odd domains (bubbles) that were possibly created in heavy-ion collisions. In the presence of the magnetic field produced by the valence quarks of colliding ions, parity-odd domains generate electric field. Quarkonium dissociation is the result of quantum tunneling of quark or antiquark through the potential barrier in this electric field. The strength of the electric field in the quarkonium comoving frame depends on the quarkonium velocity with respect to the background magnetic field. We investigate momentum, electric field strength and azimuthal dependence of the dissociation rate. Azimuthal distribution of quarkonia surviving in the electromagnetic field is strongly anisotropic; the form of anisotropy depends on the relation between the electric and magnetic ...

Energy Technology Data Exchange (ETDEWEB)

The study of interaction of tachyons with superluminal electromagnetic fields has been undertaken and it has been shown that the energy of this interaction is similar to that of bradyons with ordinary electromagnetic fields except that the roles of virtual and longitudinal parts are interchanged. It has also been shown that the interaction of tachyons with superluminal electromagnetic fields in time-energy representation is identical to the interaction of bradyons with ordinary electromagnetic fields in space-momentum representation. 19 references.

Scientific Electronic Library Online (English)

Abstract in english We present a detailed derivation of the effective dielectric constant to be used in the dispersion relation for electrostatic waves in the case of a plasma immersed in a inhomogeneous magnetic field, with inhomogeneity perpendicular to the direction of the magnetic field.

Energy Technology Data Exchange (ETDEWEB)

The authors have investigated here whether tachyons can move in stable circular orbits in Kerr, Kerr-Newmann and Lewis fields owing to their dragging effect. It is found that stable circular orbits are possible only in a Lewis field.

Science.gov (United States)

A new type of radiation which occurs when particles are accelerated in the field of a longitudinal wave and in a transverse magnetic field is studied. The characteristics of such spontaneous radiation are obtained, and the influence of collective effects on the radiation is analyzed. The application of the findings to the theory of free electron lasers is discussed. 8 references.

UK PubMed Central (United Kingdom)

The receptive field of a neuron reflects its function. For example, for parallel fiber (PF) inputs in C3 zone the cerebellar cortex, the excitatory and inhibitory receptive fields of a Purkinje cell...Full Text Available

International Nuclear Information System (INIS)

The energy-momentum tensor of a massless spinor field is constructed and studied based on the previously proposed interpretation of quantum effects of such a field in the anisotropic metric of Bianchi type IX. The characteristic properties of the energy-momentum tensor in the mixed universe model are discussed.

Energy Technology Data Exchange (ETDEWEB)

Comparison of dosimetry measured in a noncylindrical Rando-Alderson phantom by two-field, four-field, and six-field total-skin electron-beam therapy (TSEBT) techniques with our dual-field rotational (DFR) technique reveals a superior dosimetry for the latter. Our technique of dual-field rotational DFR-TSEBT is described in detail, and its advantages and indications for the primary management of cutaneous T-cell lymphoma (CTCL) and Kaposi's sarcoma (KS) are discussed.

UK PubMed Central (United Kingdom)

OBJECTIVE--The study was performed to examine the influence of the exposure to magnetic fields in the potrooms of an electrolysis plant on the occurrence of musculoskeletal symptoms among the employees....Full Text Available

International Nuclear Information System (INIS)

An overview is given the expected amount of natural gas that can be produced from small gas fields in the Netherlands in the next 20 years.

International Nuclear Information System (INIS)

... range magnetic fields magnetic susceptibility magnetization neutron diffraction

British Library Electronic Table of Contents (United Kingdom)

Academic, government, and industrial field researchers have generated a significant database of field studies of the volatility of soil applied fumigants. However, limited work exists in validating physical models against field volatility data sets and fully exploring the volatility parametric response surface. Field studies quantifying atmospheric flux for soil fumigants 1,3-dichloropropene and chloropicrin are validated against the United States Department of Agriculture (USDA Salinity Laboratory) soil physics model CHAIN_2D that was modified specifically for agronomic uses of soil fumigants. Comparison between model predictions and field observations for six unique field trials in five different states indicate that CHAIN_2D effectively captures the magnitude and duration of fumigant em...

International Nuclear Information System (INIS)

... parameters magnetic fields magnetic properties magnetization monocrystals

International Nuclear Information System (INIS)

The first cohomology of the Virasoro algebra with coefficients in string fields are investigated. The relation between them and the Nambu-Goto action for a closed string is established. (orig.).

Energy Technology Data Exchange (ETDEWEB)

In the present work the effect of different surface conditions on plasma nitriding response of AISI M2 high speed steel was investigated. The plasma nitriding of ground and sandblasted samples and drills was performed at temperatures of 400 C and 500 C for two gas mixtures: 5 vol.% N{sub 2} and 76 vol.% N{sub 2} in hydrogen. Surface layers were characterized before and after plasma nitriding concerning the microstructure, roughness, microhardness, chemical composition, phase composition and residual stress states. Machining tests were carried out with drills during which drilling forces and flank wear have been measured. A significant effect of the surface state prior to nitriding on residual stress states and the properties of the nitrided layer and untreated core has been observed. Thinner nitrided layers on ground and sandblasted samples were attributed to high compressive residual stress states and a stress affected diffusion of nitrogen and carbon. In the ...

International Nuclear Information System (INIS)

Since the mid-1990s, nuclear power plants in Korea have experienced wall thinning, leaks, and ruptures of secondary side piping caused by flow-accelerated corrosion (FAC). The pipe failures have increased as operating time progresses. In order to prevent the FAC-induced pipe failures and to develop an effective FAC management strategy, KEPRI and KOPEC have conducted a study for developing systematic FAC management technology for secondary side piping of all Korean nuclear power plants. As a part of the study, FAC analyses were performed using the CHECWORKS code. The analysis results were used to select components for inspection and to determine inspection intervals on each nuclear power plant. This paper describes the introduction of the FAC analysis method and the wall thinning trend analysis results by reactor type, system, and water treatment amine. This paper also represents the site application feasibility for secondary side piping management. The site application feasibility of ...

Science.gov (United States)

Al2O3-based ceramic is one of the most widely used materials for tools employed in hardened steel turning applications due to its high hardness, wear resistance, heat resistance and chemical stability. The objective of this work is to predict the lives of Al2O3-(W, Ti)C ceramic tools in intermittent turning of hardened AISI 1045 steel by means of damage evolution model taking into account the mechanical loading and thermal effect in the cutting process. A damage evolution model analyzing the RVE with uniformly distributed interacting cracks is constructed based on micromechanics. The calculated results of the proposed damage evolution model are compared with the lives of two kinds of Al2O3-(W, Ti)C ceramic tools obtained through experiments. It is found that the proposed model can be used to predict the lives of the ceramic cutting tools in intermittent turning operation.

Energy Technology Data Exchange (ETDEWEB)

The present work describes the surface improvement and biocompatibility of TiAl{sub 24}Nb{sub 10} intermetallic alloy using rf plasma nitriding. The nitriding process was carried out at different plasma power from 400 W to 650 W where the other plasma conditions were fixed. Grazing incidence X-ray diffractometry (GIXRD), Auger electron spectroscopy (AES), tribometer and a nanohardness tester were employed to characterize the nitrided layer. Further potentiodynamic polarization method was used to describe the corrosion behavior of the un-nitrided and nitrided alloy. It has been found that the Vickers hardness (HV) and corrosion resistance values of the nitrided layers increase with increasing plasma power while the wear rates of the nitrided layers reduce by two orders of magnitude as compared to those of the un-nitrided layer. This improvement in surface properties of the intermetallic alloy is due to formation of a thin modified layer which is composed of titanium ...

Energy Technology Data Exchange (ETDEWEB)

A hose lining process, used widely for underground service structures, such as for city gas, and water and sewerage pipes, was adopted to repair interiors of underground wire raceways, and improvements were made for power cable pipe use, including long size construction, inner diameter assurance, and flame retardation. The sealing hose as a lining material consists of a fabric layer woven by warps of polybutylene terephthalate (PBT) and wefts of combined PBT fibers and glassfibers, the fabric being coated with polyurethane resin on one side. The other side of the fabric is coated with heat hardening resin made of epoxy resin as the main ingredient and aromatic amine as the hardening agent to assure close adhesion of the sealing hose onto the pipe interior. Mimic raceways were used to verify the lining material for its abrasion coefficient, mechanical strength, wear resistance, water cut-off performance, chemical resistance, and shape retention performance against ...

Energy Technology Data Exchange (ETDEWEB)

The durability of ball bearings, 32-mm- and 45-mm-bore, with a retainer or glass cloth-polytetrafluoroethylene (PTFE) laminate was tested under a high radial load at a speed of 20,000 rpm in LOX or LN2. The retainers were characterized as good self-lubricators because the abrasive glass-cloth fiber tips exposed on the retainer were chemicaly etched away with hydrofluoric acid (HF). During testing, the bearing-cartridge-acceleration was monitored to detect bearing damage. Testing in LOX for about 2.2 hr showed that excellent lubricating conditions were obtained for all bearings. Testing in LN2 for about 5.1 hr detected that the fatigue life of the bearing was about the same as the calculated B10 fatigue life. The HF chemical treatment resulted in a reacted fluoride-oxide material which remained in the etched part of the glass fiber. Several chemical products, particularly MgO, CaO, and CaCO3, enhanced adhesion of PTFE transfer film to the counterface, resulting in the formation of a ...

Energy Technology Data Exchange (ETDEWEB)

A systematic study was made on MoSi{sub 2}-based nanolayer coatings. Alternating layers with thickness 1-20 nm were prepared by sputtering. Nitrided MoSi{sub 2} has a very high crystallization temperature, >1000 C, and MoSi{sub 2}Nx (x=3-4) can be used as a stable second phase reinforcement or diffusion barrier coatings. Mechanical properties depend strongly on phase and morphology of the layers: hardness and modulus is significantly increased in the crystallization. The nanolayers have much higher hardness but lower modulus (which project higher toughness in the nanolayers). Wear resistance is improved with decreasing layer thickness. Single phase MoSi{sub 2}Nx (x=0-4.2) has a wide range of hardness and modulus with varying N content and annealing, suggesting the possibility of engineering MoSi{sub 2}Nx to produce different material properties for different mechanical applications. Most of this paper is made up of viewographs.

Energy Technology Data Exchange (ETDEWEB)

This work analyzes the unoptimized prototype triode-sputtered, 150 microns thick tantalum coatings deposited with a 2.5 microns niobium underlayer on the bore of a large-diameter A723 steel cylinder. The coating was deposited for wear and erosion protection by Pacific Northwest National Laboratory. The phase determination was based on X ray diffraction analysis, wavelength dispersive X ray fluorescence analysis, energy dispersive X ray analysis, and hardness and electrical resistivity measurements. Both X ray diffraction and radius-of- curvature methods were used to determine residual stresses. A locally developed high-resolution pole figure technique was used to perform texture analysis. The post-firing, debonded coating showed alpha-tantalum, preferred 110 orientation, high surface stresses, tantalum oxides, entrapped krypton sputtering gas, interstitial oxygen, and other impurities. The surface and subsurface pole figures revealed broadened poles and ...

International Nuclear Information System (INIS)

As a hardening process, the attractiveness of nitriding lies in its low treatment temperature. Although the thickness of the case is less than that obtained by higher temperature processes such as carburising, there are a range of alloys and applications for which nitriding is the only possible alternative. Indeed, there are some alloys and applications for which even the normal nitriding temperatures (between 500 deg C and 600 deg C for ferrous alloys) are too high. In this paper, we report on developments, specifically the use of low pressure plasmas and high energy ion bombardment, which can extend the benefits of nitriding to lower temperatures. In this poster, we will present results from these collaborative projects, concentrating on the nitriding of austenitic stainless steel at temperatures below 450 deg C. In this temperature range, the hardness and wear resistance of the surface can be improved without compromising the corrosion resistance of the ...

Energy Technology Data Exchange (ETDEWEB)

To improve the surface properties of magnesium alloy, a lining process using shot peening was carried out. The lining of magnesium alloy with metals such as titanium and nickel is useful in heightening the corrosion and wear properties for the components. In the shot peening experiment, the foil set on the magnesium workpiece is pelted with many shots at a high velocity. The foil is bonded to the surface of the workpiece due to plastic deformation induced by the collision of the shots. A pure aluminum foil is inserted between the hard foil and magnesium workpiece to assist the bonding. To heighten the bondability, the foil and workpiece are heated and the flow stresses of the metals are reduced. In this experiment, a centrifugal shot peening machine with an electrical heater was employed. The workpieces were commercially magnesium alloys AZ31B and AZ91D, and the foils were commercially pure aluminum, pure titanium and pure nickel. The effects of collision speed and ...

Energy Technology Data Exchange (ETDEWEB)

A series of plasma nitriding experiments has been conducted on AISI 304L austenitic stainless steel at temperatures ranging from 375 to 475 C using pulsed-DC plasma with different pulse duty cycles, N{sub 2}-H{sub 2} gas mixtures and treatment times. It is shown that a wide range of treatment parameters exist that allow the formation of the S-phase. The formation and growth of this surface layer depend strongly on the treatment parameters, such as nitrogen partial pressure and duty cycle. Within the parameter range investigated, the layer growth appears to be diffusion controlled with an activation energy about 107 kJ/mol. The formation of CrN precipitates during plasma nitriding is not accompanied by the formation of bcc iron, which might be expected due to the loss of free chromium. However, the S-phase transforms into CrN and bcc iron following a heat treatment at 450 C or higher for 25 h. The wear rate after plasma nitriding is greatly reduced compared with the ...

Energy Technology Data Exchange (ETDEWEB)

Microelectronic failure analysis (FA) has been an integral part of the development of state-of-the-art integrated circuits. FA of MicroElectroMechanical Systems (MEMS) is moving from its infancy stage to assume an important role in the successful design, fabrication, performance and reliability analysis for this new technology. In previous work, the authors focused on the application of several techniques developed for integrated circuit analysis to an earlier version of a surface micromachined microengine fabricated at Sandia. Recently, they have identified important new failure modes in binary counters that incorporate a newer design of the microengine, using a subset of integrated circuit failure analysis techniques including optical microscopy, focused ion beam (FIB) techniques, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The primary failure mode they have identified is directly related to visible wear on bearing surfaces. In this ...

International Nuclear Information System (INIS)

Activation has been used for many kinds of useful applications, such as use of the radioisotopes for diagnosis and treatment of cancer, and wear (or corrosion) investigation for using thin layer activation (TLA) technique, etc. But activation also has severe problems for the post-processing of the samples; such as time-loss, inconvenience of sample handling, personal radiation safety, etc. For in-vitro experiments, we observed death of tumor cells by proton irradiation. The use of large activated container material can cause erroneous results in this case. To solve these problems, we studied why the samples were activated and how the level of the activation could be reduced. In proton beam irradiation experiments, the target materials could be defined as the container and sample itself. We could easily reduce activation of container material comparing to activation of sample itself. Therefore, we tried to find less activated container material by irradiating proton ...

KoreaScience (Korea)

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Science.gov (United States)

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KoreaScience (Korea)

Full Text Available

Science.gov (United States)

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CERN Document Server

We study the dynamics of the scalar tensor cosmological model in the presence of tachyon field. In an alternative approach, in two exponential and power law form of the scalar field functions in the model, field equations are solved by simultaneously best fitting the model parameters with the most recent observational data. This approach gives us an observationally verified interpretation of the dynamics of the universe. We then discuss the best fitted of equation of state parameter, the statefinder parameters and the reconstructed scalar field in the model.

Energy Technology Data Exchange (ETDEWEB)

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International Nuclear Information System (INIS)

... fields magnetic moments neel temperature neutron diffraction order-disorder

Energy Technology Data Exchange (ETDEWEB)

The influence of rigid-body and differential rotation and of a fine-scale chaotic magnetic field and a poloidal magnetic field on the minimum mass of a main-sequence star is investigated. It is shown that rotation and a magnetic field with an energy equal to 10--20% of the star's gravitational energy increase the minimum mass of a main-sequence star by 1.5--2 times.

CERN Document Server

A last look at the green field, in the triangular wedge of land stray radiation near the CERN accelerators.

Science.gov (United States)

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KoreaScience (Korea)

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KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

KoreaScience (Korea)

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KoreaScience (Korea)

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Science.gov (United States)

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UK PubMed Central (United Kingdom)

This study investigated the effects of electromagnetic fields on enzymes involved in purine metabolism in human peripheral blood mononuclear cells in vitro. Cells were obtained from 20 volunteers. We...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In the Ti-Si-C and Ti-Si-C-N systems, metastable layers were precipitated by means of non-reactive magnetron sputtering of hot-pressed two-phase TiC/SiC and TiN/SiC targets with 20 mole% and 50 mole% SiC. The preparation parameters were varied as follows: ion bombardment during precipitation (bias sputtering), substrate temperature, and annealing times when annealing amorphous 50%:50% TiC/SiC and 50%:50% TiN/SiC layers. Sputtering of targets containing 20% SiC was found to result in monophase fcc layers (NaCl structure). This was documented on the basis of X-ray and electron diffraction patterns. Direct precipitation of targets with 50 mole% SiC resulted in amorphous layers. Increasing the ion bombardment during accretion, raising the substrate temperature, and annealing amorphous 50%:50% TiC/SiC and 50%:50% TiN/SiC (layers precipitated directly) resulted in the crystallization of TiC and TiN nanocrystallites, respectively, imbedded in an amorphous SiC matrix. These crystallites were ...

International Nuclear Information System (INIS)

This paper presents some situations, in which measurements of electromagnetic fields generated by transmission lines and substations should be performed. The range of measurements may differ, but maximum values of electric and magnetic fields and flux density must be identified in all situations. The area with electric field exceeding 1 kV/m should be identified as well. The author also presents basic requirements to be met by the measurement technique. These requirements are specified according to the national standard. Special attention should be paid to the identification of the spatial distribution of electric field and flux density generated in the vicinity of high voltage transmission lines. To verify the measurement results, it is necessary to calculate the distribution of both aforesaid field components. For environmental protection purposes, it is also proposed that the ...

International Nuclear Information System (INIS)

Three dimensional temperature field and helium flow field of TBM are simulated using the general purpose computational fluid dynamics (CFD) code FLUENT. The temperature distribution of Be Armor, Be Pebble Bed, Li_4SiO_4 Pebble Bed, Structure Material of TBM, and helium flow field in the cooling pipe are presented. The research indicates that the work temperature of each material is under the material temperature allowed except some places where high temperature should be excluded in the design. The results will provide references for further optimized thermal hydraulic design of ITER China TBM. (authors)

International Nuclear Information System (INIS)

We estimate the optimum electric field at the sheath edge and the minimum interval among the nanotubes to promote the growth of armchair-type nanotubes (metallic character) as a function of the tube length. On the basis of the electric charge distribution in a nanotube and the optimum electric filed E*_1 at the tip of a nanotube evaluated using the Hueckel-Poisson method, we calculate the structure of the electric field lines outside a nanotube in the sheath region. As the tube length increases, the E*_1 decreases. To maintain the chemical activity at the tip, the sheath electric field must be decreased. We show the decreasing rate of the sheath field to the tube length.

Energy Technology Data Exchange (ETDEWEB)

The magnetoresistance in an FeNi submicron-structure comprising two wires of 80 and 200 nm in width connected in series was measured at 77 K. When the external magnetic field was applied parallel to the wire axis, two switching fields corresponding to the distinct coercive force of the two wires were observed. When the external magnetic field was applied at an angle of {theta}>30 deg. to the wire axis one switching field was observed, indicating simultaneous magnetization reversal in both wires. This indicates that the domain-wall trapping around the joint can be controlled systematically in terms of the direction of the external magnetic field.

Energy Technology Data Exchange (ETDEWEB)

The diagonal and symmetric Bianchi type IX models are coupled to a homogeneous spinor field. An action for the combined fields is constructed, where the orthonormal basis used is given explicitly in terms of the metric. This allows one to vary the action with respect to the metric and the spinor fields only. Next, a Hamiltonian formulation is given, and a qualitative solution for the problem is presented. We also show that the k = +1 FRW (Friedmann--Robertson--Walker) model is not compatible with a homogeneous spinor field, while the more complicated models are.

Energy Technology Data Exchange (ETDEWEB)

The cell is modeled as an ellipsoid with shell and the surface stress distribution calculated by means of the Maxwell Stress Tensor. The cell membrane is treated as incompressible material having both bending and shear energies of deformation. Employing the principle of virtual work, cell volume (and hence shape) is computed as a function of the external field strength and orientation with respect to the field. The following results were obtained: (1) The surface stresses that develop or the cell membrane are distributed having both normal and tangential components that act together to produce a rounding of the cell. (2) If the tangential component of the stress is ignored, then higher field strengths are needed to produce similar deformation (shape change) of cells. (3) The threshold value of the applied field, i.e, the field strength at which the volume (shape) of the cell changes ...

International Nuclear Information System (INIS)

Exact expressions for wave electromagnetic fields during instantaneous braking of two differently charged discs uniformly moving in the opposite directions have been derived. Analysis of their properties has been made. It is shown that electromagnetic wave fields during instantaneous braking of charges have a tearing nature and the Umov-Poynting theorem in the integral form is realized only at a certain value of parameter #alpha# which determines charges rates at the moment of braking. The value of parameter #alpha# is in the ranges from 0.5 to #sq root#3/2. The wave field is formed already in the absence of motion of charged discs. It is a good example confirming the conclusion that in the case of nonstationary electromagnetic fields, performance of reaction force of the wave field can differ fram radiation energy.

International Nuclear Information System (INIS)

Electrodynamic properties of processes involving charged tachyons are considered in connection with the real superluminal Lorentz transformations. These transformations are interpreted without making use of a tachon corridor and so that the interaction of tachyons from subluminal sources with ordinary matter is Lorentz invariant. Transformations of the electromagnetic fields are deduced from the extended principle of relativity. They are necessary in order to obtain the field equations that are satisfied by fields obeying Maxwell equations relative to superluminal inertial frames with respect to subluminal inertial frames. The field equations allow one to get the dependence of the field energy density and its current on the field strengths. The resulting equations are applied in a discussion of plane electromegnetic waves, sent out by a superluminal source. The ...

Energy Technology Data Exchange (ETDEWEB)

The Mississippi Office of Geology has conducted field trials using the surface exploration techniques of geomicrobial, radiometrics, and free soil gas. The objective of these trials is to determine if Mississippi oil and gas fields have surface hydrocarbon expression resulting from vertical microseepage migration. Six fields have been surveyed ranging in depth from 3,330 ft to 18,500 ft. The fields differ in trapping styles and hydrocarbon type. The results so far indicate that these fields do have a surface expression and that geomicrobial analysis as well as radiometrics and free soil gas can detect hydrocarbon microseepage from pressurized reservoirs. All three exploration techniques located the reservoirs independent of depth, hydrocarbon type, or trapping style.

Science.gov (United States)

The calculations of Gay et al. of the terminal velocities of charged hydrormeteors in the presence of electric fields have formed the basis of computations of the charging current density J flowing through a thunder-cloud as a result of the operation of a precipitative mechanism of cloud electrification. Values of J were calculated for a range of values of field strength E, precipitation rate pO, precipitation content L, cloud water content C, charge distribution, total separated charge, and the fraction of the small particles that have undergone a charging event.It is found that the estimated field required for the initiation of a lightning stroke (3.5 kV cm1 can be achieved only over a narrow range of conditions. The ease with which precipitative mechanisms can produce breakdown fields is considerably increased, however, if account is taken of spatial inhomogenities in the field.

CERN Document Server

In the paper the role of conservation laws in evolutionary processes, which proceed in material systems (in material media) and lead to generation of physical fields, is shown using skew-symmetric differential forms. In present paper the skew-symmetric differential forms on deforming (nondifferentiable) manifolds were used in addition to exterior forms, which have differentiable manifolds as a basis. Such skew-symmetric forms (which were named evolutionary ones since they possess evolutionary properties), as well as the closed exterior forms, describe the conservation laws. But in contrast to exterior forms, which describe conservation laws for physical fields, the evolutionary forms correspond to conservation laws for material systems. The evolutionary forms possess an unique peculiarity, namely, the closed exterior forms are obtained from these forms. It is just this that enables one to describe the process of generation of physical ...

Energy Technology Data Exchange (ETDEWEB)

The selection and design of an MEOR process for application in a specific field involves geological, reservoir, and biological characterization. Microbially mediated oil recovery mechanisms (bigenic gas, biopolymers, and biosurfactants) are defined by the types of microorganisms used. The engineering and biological character of a given reservoir must be understood to correctly select a microbial system to enhance oil recovery. This paper discusses the methods used to evaluate three fields with distinct characteristics and production problems for the applicability of MEOR would not be applicable in two of the three fields considered. The development of a microbial oil recovery process for the third field appeared promising. Development of a bacterial consortium capable of producing the desired metabolites was initiated, and field isolates were characterized.

International Nuclear Information System (INIS)

Understanding human brain function, brain development and brain dysfunction is one of the great challenges of the twenty first century. Biomedical imaging has now run up against a number of technical constraints that are exposing limits to its potential. In order to overcome the current limits to high-field magnetic resonance cerebral imaging (MRI) and unleash its fullest potential, the Cea has built NeuroSpin, an ultra-high-field neuroimaging facility at its Saclay centre (in the Essonne). NeuroSpin already boasts three fully operational MRI systems. The first is a 3-tesla high-field system and the second is a very-high-field 7-tesla system, both of which are dedicated to clinical studies and investigations in humans, while the third is an ultra-high-field 17.65-tesla system designed for studies on small animals. In 2011, NeuroSpin will be commissioning an 11.7-tesla ...

Science.gov (United States)

C-130J payload reduced to make radius. ** Current C-17A uses 3000 ft field, C- 17A+ estimated cost of $378M per plane with. 2000 ft field length, ...

UK PubMed Central (United Kingdom)

BackgroundMagnetic Resonance Imaging scanners have become ubiquitous in hospitals and high-field systems (greater than 3 Tesla) are becoming increasingly common. In light of recent...Full Text Available

UK PubMed Central (United Kingdom)

OBJECTIVES: This article uses meta-analysis methodology to examine the statistical consistency and importance of random variation among results of epidemiologic studies of residential magnetic field...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Relativistic mean field (RMF) theory is applied to modern problems of nuclear structure, such as the description of rotating bands in super-deformed nuclei or the investigation of neutron halos in light exotic nuclei. (orig.)

UK PubMed Central (United Kingdom)

Genetic algorithms (GA) were used to develop specific copper metal-ligand force field parameters for the MM3 force field, from a combination of crystallographic structures and ab initio...Full Text Available

Science.gov (United States)

We obtain the radial Dirac equations for the Plebanski metric and transform these equations into one-dimensional wave equations. Finally we conclude with the result that the electron and the neutrino fields are not superradiant.

Environmental Research Database

DescriptionThe UK horticulture and agriculture industries rely on large inputs of mineral nitrogen (N), phosphorus (P) and potassium (K) fertilisers to maintain product yield and quality. Recovery of applied fertilisers by field crops is inefficient (routinely