Effect of Carbon Nanotube Addition on Tribological Behavior of UHMWPE

Carbon nanotubes (CNTs) were added to Ultra-high molecular weight polyethylene (UHMWPE) to improve the tribological properties of UHMWPE. CNTs which have a diameter of about 10–50 nm, while their length is about 3–5 nm were produced by the catalytic decomposition of acetylene gas using a tube furnace. Ball-on-disc-type wear tests were performed to evaluate the tribological performance of UHMWPE composites reinforced with CNTs. The results showed that addition of carbon nanotube up to 0.5 wt% lowered wear loss significantly and increased friction coefficient slightly. Also through the scanning electron microscope (SEM), the surfaces of UHMWPE were observed and analyzed to discuss the tribological behavior of CNT added UHMWPE.     

A Position-Sensitive Optical Detector Based on Anomalous Photovoltage Films

A laboratory method for manufacturing position-sensitive optical detectors based on thin films of the CdTe-type semiconductors is described. These detectors are capable of generating anomalously high photoelectric voltages. To render a detector position-sensitive, the film thickness is increased stepwise, starting at ∼1 µm (for CdTe films).__________Translated from Pribory i Tekhnika Eksperimenta, No. 4, 2005, pp. 125–126.Original Russian Text Copyright © 2005 by Rakhimov, Ser’eznov.     

Measuring and Visualizing Strong Magnetic Fields by Means of Indicators Based on Garnet Ferrite Films

A method for measuring by means of indicators based on garnet ferrite films the strong magnetic stray fields having intensities of 5–10 kOe that arise in systems of magnets with enormous magnetic anisotropy is described. The method is based on the phase transition from a strip domain structure into a uniformly magnetized state that takes place in garnet ferrite films in magnetic fields with intensities approaching the values of their anisotropy fields. It is shown that, by using indicators with various anisotropy field values, it is possible to obtain a fairly complete pattern of the stray fields localized in a narrow region over the magnets. The resolution limit in the localization region of a strong field is comparable to the width of the strip domains in the indicator and is 1–4 µm. The limiting value of the measured field intensity is equal to the anisotropy field of the indicator material.__________Translated from Pribory i Tekhnika Eksperimenta, No. 4, 2005, pp. 89–94.Original Russian Text Copyright © 2005 by Il’yashenko, Lubyanyi, Samofalov.     

Nanotribological behavior of tethered reinforced polymer nanolayer coatings

We fabricated molecularly thick thermoplastic elastomeric films with organized microdomain structure and intriguing nanotribological properties. Molecular films from poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) were obtained by a melt/solution grafting to a functionalized silicon surface modified with epoxy-terminated self-assembling monolayers. We varied the thickness of grafted block–polymer films from 1.35 nm (disordered polymer layer) to 9 nm (well defined nanophase structure) and tested their friction, adhesion, shear and wearing properties on a microscale with scanning probe microscopy. Tethered SEBS monolayers, composed of a rubber matrix reinforced by a two-dimensional net of glassy polystyrene (PS) microdomains, possess a friction coefficient as low as 0.02 and shear strength in the range 0.15–1.5 GPa. Chemically tethered SEBS monomolecular films are much more stable under shear stresses than conventional molecular coatings.     

A Solar Blind Filter for the Ultraviolet Spectral Range

Transmission factors of potassium films of different thicknesses are calculated. A prototype of a potassium-based solar blind filter for the ultraviolet spectral range was developed. The filter transmission factor is 20–30% in a spectral band of 200–300 nm.     

Evidence of commensurate contact and rolling motion: AFM manipulation studies of carbon nanotubes on HOPG

We report on experiments in which multiwall carbon nanotubes (CNTs) are manipulated with AFM on a graphite (HOPG) substrate. We find certain discrete orientations in which the lateral force of manipulation dramatically increases as we rotate the CNT in the plane of the HOPG surface with the AFM tip. The three-fold symmetry of these discrete orientations indicates commensurate contact of the hexagonal graphene surfaces of the HOPG and CNT. As the CNT moves into commensurate contact, we observe the motion change from sliding/rotating in-plane to stick–roll motion.     

Electric contact resistance between finely polished nickel plates with PFPE coating and its relation to friction

The electric contact resistance between mechanically polished nickel plates, with one side dip-coated in perfluoropolyether (PFPE), was evaluated under statically loaded and sliding conditions to investigate the isolation property of the PFPE coating, which may have an important role in thin-film lubrication on relatively large, minutely rough, plane surfaces. The nickel plate surfaces had a roughness of 1–3 nm and the PFPE coating had a thickness of 4–6 nm. Two types of relationship between load and contact resistance were observed. One was estimated to be for a uniform coating of the oil film, the other for a patchy one. Friction tests revealed that a uniform coating of oil film would be preferable to a patchy one to prevent solid–solid contact, if the nominal thicknesses of the oil films were similar.     

Tribology of X-1P vapor lubricated hard disks

The tribological characteristics of vapor lubricated X-1P films on carbon coated disks were investigated as a function of lubricant thicknesses (0.2–2 nm) and compared with traditionally dip-coated X-1P and PFPE films. Glide and flyablity tests were performed and the lubricant redistribution in the ‘wear track’ was investigated using a surface reflectance analyzer (SRA). A critical lubricant thickness was found to exist for X-1P below which lubricant accumulation was observed, while lubricant loss was found to be present if the thickness of the lubricant film was greater than the critical thickness.     

Mechanical properties and tribological behavior of ZrO<Subscript>2</Subscript> thin films deposited on sulfonated self-assembled monolayer of 3-mercaptopropyl trimethoxysilane

A silane coupling reagent (3-mercaptopropyl)trimethoxysilane (abridged as MPTS) was self-assembled on a single-crystal Si substrate to form a two-dimensional organic monolayer (MPTS-SAM). The terminal –SH group in the MPTS-SAM film was in-situ oxidized to –SO₃H group to endow the film with good chemisorption ability. Then ZrO₂ thin films were deposited on the oxidized MPTS-SAM by way of the enhanced hydrolysis of aqueous zirconium sulfate (Zr(SO₄)₂·4H₂O) in the presence of aqueous HCl at 50 °C, making use of the chemisorption ability of the –SO₃H group. The thickness of the ZrO₂ films was determined with an ellipsometer, while their morphologies and corresponding friction forces were analyzed by means of atomic force microscopy. The hardness and elastic modulus of the ZrO₂ thin films were determined on a Nanoindentation II (MET) instrument. The macro-friction and wear behaviors of the ZrO₂ films sliding against an AISI-52100 steel ball were examined on a unidirectional friction and wear tester and the worn surface morphologies observed on a scanning electron microscope (SEM). As the results, the as-deposited ZrO₂ thin film at a deposition duration of 100 h is about 100 nm thick, it decreases to 48 nm after annealing at 500 °C and further decreases to 45 nm after heating at 800 °C. The as-deposited ZrO₂ film is relatively rougher, with the rms to be about 1.0 nm, while the ZrO₂ thin films heated at 500 and 800 °C have surface roughness rms of 0.76 nm and 0.68 nm, respectively. The ZrO₂ film annealed at 800 °C has a high hardness to elastic modulus (H/E) ratio (0.062) as compared to the as-deposited ZrO₂ film and the film annealed at 500 °C. Both the two annealed ZrO₂ films show excellent wear-resistance as they slide against AISI-52100 steel at a normal load below 2.0 N, while the one annealed at 800 °C has better wear-resistance. The differences in the friction and wear behaviors of the as-deposited ZrO₂ film, the ZrO₂ film annealed at 500 °C and that annealed at 800 °C are attributed to their different micro structures and compositions. Since the ZrO₂ films was well adhered to the underlying MPTS-SAM, it might find promising application in the surface-protection of single crystal Si and SiC subject to sliding at small normal load in microelectromechanical systems (MEMS).     

A Method for Evaluating the Thickness of Ultrathin Films

A method for determining the thickness of ultrathin (<10 nm) films using an atomic-force microscope is described. Films were deposited onto a porous glass substrate that has smooth surface areas between the pores when the flow of the evaporated material incident on the substrate is at an angle of 20°–30° with respect to the normal to its surface. In order to obtain pores with sharp edges, the substrate surface was preliminarily sputtered by an oxygen ion beam directed at an angle of 90° to this surface. Images of such films obtained using the atomic-force microscopy technique clearly resolve the position of the pore edge–film boundary, making it possible to evaluate the film thickness by the height of the step between the pore edge and the by surface in the cross section of the surface topography.     

The Contribution of Thin PFPE Lubricants to Slider–Disk Spacing

We have investigated the effect of the molecular weight (MW) and film thickness of a perfluoropolyether lubricant, Zdol, on the slider–disk spacing loss, or clearance. The major conclusion of this work is that Zdol films as thin as 10 Å can reduce the slider–disk clearance by 2 nm or more in the molecular weight range of 1000–5000 amu. This is attributed to the attractive van der Waals interaction between the slider and the disk surface that causes the Zdol main chain to interact with the slider surface, giving rise to a friction force. When the film thickness of the lubricant exceeds the monolayer thickness, dewetting can take place. The droplets that form occupy the space between the slider and disk surface reducing the slider–disk clearance by as much as 4 nm. There is a step increase in the acoustic emission signal at the dewetting thickness transition, indicative of a slider–disk interference.     

Nondestructive Testing of Mechanical Properties of Rolled Steel (Review): 1. Tests of Strength and Plastic Properties

This review considers the creation and development of a nondestructive technique based on coercive-force measurements used to determine strength and plastic properties of industrial rolling products made from Russian-produced low-carbon and low-alloy steels. The operating principle for a coercimeter equipped with a field electromagnet is described briefly. Regression lines of mechanical properties versus coercimeter readings are presented for 20Κ- and 09Γ2-steel sheets produced by Nizhni Tagil Iron and Steel Works. Different methods for considering sheet thickness and tube dimensions are discussed.__________Translated from Defektoskopiya, Vol. 41, No. 5, 2005, pp. 39–52.Original Russian Text Copyright © 2005 by Bida.     

Applying the Adiabatic Demagnetization Technique to Detect Explosive Substances by the Nuclear Quadrupole Resonance Method

An experiment in applying the adiabatic demagnetization technique to considerably increase the sensitivity of the nuclear quadrupole resonance (NQR) method for the multipulse detection of one of the most widely used explosives—pentaerythritol tetranitrate (PETN)—is described. The results were obtained using a highly inhomogeneous magnetic field produced by permanent magnets. The dependences of the NQR signal enhancement on the carrier frequency offset and the time during which the sample was kept in the magnetic field were studied while using the adiabatic demagnetisation technique.__________Translated from Pribory i Tekhnika Eksperimenta, No. 3, 2005, pp. 132–135.Original Russian Text Copyright © 2005 by Mikhaltsevich, Belyakov.     

Shock-squeezed metal-insulator-metal films at high-speed impacts of micrometeoroid and technogenic particles

The mechanisms of the interaction of high-speed particles with metal-insulator-metal (MIM) film structures were studied using electrostatic accelerators. Experimental dependences of signals from shock-squeezed and particle-punched MIM structures on the mass and velocity of particles in the ranges 10^–9–10^–13 g and 0.3–7 km s^–1, respectively, were obtained. An ionization-capacitor device was developed and built for detecting micrometeoroid particles.__________Translated from Pribory i Tekhnika Eksperimenta, No. 2, 2005, pp. 123–129.Original Russian Text Copyright © 2005 by Semkin, Voronov, Novikov, Bogoyavlenskii.     

Characteristics of the energy filter for an MX7304A mass spectrometer

The transmission curves of the energy filter for an MX7304A mass spectrometer are determined by analyzing the transmission of an ion beam with a small ion-energy spread through the filter. A beam of potassium ions produced by heating a tungsten ribbon coated with a layer of potassium hydroxide was used.__________Translated from Pribory i Tekhnika Eksperimenta, No. 2, 2005, pp. 120–122.Original Russian Text Copyright © 2005 by Baturin, Eremin.     

Evaluation of the friction of WC/DLC solid lubricating films in vacuum

The accuracy of nanopositioning is to a large extent limited by the friction-caused errors, particularly in vacuum environments. An investigation of the friction behaviour of sp²-bonds dominating diamond like carbon (DLC) coatings and WC_1−x/DLC, WC(N)/DLC multilayer coatings, which are considered to be used in nanopositioning in vacuum, have been performed by a vacuum microtribometer. By using an atomically smooth Si sphere as a counterface, the reciprocating sliding friction was measured at a normal load <5 mN, and running speed at a 1–100 μm/s in ambient air and in ultra high vacuum (UHV) at 10⁻⁷ Pa, and correlated with microstructures and properties of the coatings. When tested in UHV, the coefficient of friction (COF) for pure DLC coatings (thickness: 700 nm) changes significantly between 0.2 and 0.4. Once the thickness of DLC layers is limited to 5 nm by formation of multilayer coatings, the COF in UHV decreases by nearly one order to 0.02–0.05. We suggest that the deformation of DLC films and the transfer films determines COF. Thick DLC coatings can induce more plastic deformation and consumes more energy in sliding resulting in a high COF. Thickening of the transfer film in running leads to a continuous decrease of COF since the deformation of the transfer films turns easier. The low COF of multilayer coatings is mainly due to their confinement of the thickness of DLC films. A consistent velocity-strengthening frictional behaviour of both WC_1−x/DLC and WC(N)/DLC coatings in UHV indicates that the transfer films acting as a thin layer of granular material. Further study of the friction behaviour with the presence of such granular materials might be interesting for the further development of tribological coatings for vacuum applications.     

A plasmatron with interelectrode inserts for depositing diamond and diamond-like films

A plasmatron with a sectionalized interelectrode insert, intended for heating argon up to a temperature of 10 000 to 11 000 K, is described. Investigations have shown that the volt-ampere characteristics of an arc in an argon flow are ascending in the operating range of the plasmatron parameters. The thermal efficiency is as high as 0.9. The plasmatron is used in the chemical gas-phase deposition of thin wear-resistant diamond-like films with the application of a high-temperature supersonic plasma jet.__________Translated from Pribory i Tekhnika Eksperimenta, No. 2, 2005, pp. 140–143.Original Russian Text Copyright © 2005 by Sazonov, Tsyganov.     

Inspection of the Strength Characteristics and Heat-Treatment Quality of Ferromagnetic Articles Based on Parameters of the Residual-Magnetization Hysteresis Loop upon Their Local Magnetization and Magnetization Reversal in a Pulsed Magnetic Field with a Variable Amplitude: II. Steel 60C2

Effects of the tempering temperature on specimens’ hardness and on the anomalous-hysteresis loop’s and the recovery curves’ parameters for residual magnetization are experimentally studied. Test specimens made of steel 60C2 intended for laminated springs were subject to local magnetization and magnetization reversal by a pulsed magnetic field with a variable amplitude. Parameters enabling tests of the hardness of steel within three ranges of the tempering-temperature variation (0–300, 300–600, and 0–600°C) are determined.__________Translated from Defektoskopiya, Vol. 41, No. 5, 2005, pp. 14–23.Original Russian Text Copyright © 2005 by Matyuk, Mel’gui, Pinchukov, Lyubarets.     

Characterization of nanoscale recording mark on Ge2Sb2Te5 film

We have fabricated nanoscale recording marks on Ge₂Sb₂Te₅ (GST) films with conductive atomic force microscope (AFM). GST films were deposited on glass or polyimide film with thickness of 150–200 nm by the rf–sputtering method. Through current–voltage (I–V) spectroscopy, good cantilevers for fabrication and characterization of nanoscale marks on GST were selected. A fresh and highly conductive tip showed voltage-switching characteristic in the I–V curve, where the threshold voltage was 1.6 V. Nanoscale dot and wire arrays of crystalline phases were successfully obtained by varying sample bias voltage from −10 to 10 V. With highly conductive tips, nanowires having full-width at half-maximum of 20 nm could be fabricated, whereas nanowires could not be fabricated with bias voltage below −2 V. The width of the nanoscale mark was increased by repetition of AFM lithography even with same applied voltage and lithography speed. For a thicker nanowire, the width measured in current-image (C-image) was observed to be 2 times of that measured in topography-image (T-image). This result supports that current sensing provides an image of phase-changed GST area with higher resolution than topography sensing.     

A Chemiluminescent Balloon-Type Nitrogen Dioxide Meter for Tropospheric and Stratospheric Investigations (NaDA)

We have developed and produced a small and inexpensive balloon-type instrument for tropospheric and stratospheric measurements of the content of nitrogen dioxide in the atmosphere, the NaDA. The instrument utilizes the reaction of liquid luminol with NO₂, which results in the emission of light in the visible spectral region, and can operate under both tropospheric and stratospheric conditions. The range of measured concentrations is ∼ 0.1–50 ppbv; the instrument’s sensitivity is ∼26000 pulses/s per 1 ppbv of NO₂ at atmospheric pressure and its mass is ∼1 kg. Field tests of the instrument have been performed. A height profile of the NO₂ distribution in the atmosphere was obtained.__________Translated from Pribory i Tekhnika Eksperimenta, No. 3, 2005, pp. 136–141.Original Russian Text Copyright © 2005 by Sitnikov, Sokolov, Ravegnani, Yushkov, Ulanovskiy.