B. M. Ginzburg

Antiwear Effect of Fullerene C60 Additives to Lubricating Oils

The protective film (≤1000 Å thick) formed on the copper foil surface upon friction of a steel roller lubricated with industrial oil containing 5% fullerene C60 was studied by optical and electron microscopy, X-ray diffraction (XRD) analysis, hardness measurements, and mass spectrometry. This protective film is probably a fullerene-polymer network formed by fullerene C60 and covalently bound fragments of hydrocarbon chains released in the course of mechanochemical degradation of the lubricating oil. The film exhibits elevated hardness and antiwear properties, and increases the load-carrying power of the tribotechnical unit. Chemical mechanisms of tribopolymerization were analyzed.

Polymeric materials for water-lubricated plain bearings

Results of tribological studies of modern polymeric materials (thermoplastics, thermosetting materials, composites) used to fabricate water-lubricated bearings are considered. Particular attention is given to carbon-fiber-reinforced plastics modified with powdered metals, fullerene-containing additives, and carbon nanotubes.

The effect of stretching on the macromolecular structure of polymer fibres

The increase of the degree of stretching, W, of previously oriented fibres, produced from different crystalline polymers, results in an intensity decrease of the meridianal reflection, I, in low-angle X-ray scattering pictures [1–3]. The same phenomenon was described elsewhere [4] when polyvinyl alcohol (PVA) fibres were stretched at near-melting temperatures. A series of independent measurements of a whole series of structural parameters associated with changes I established that all these changed only slightly [4]. One parameter, not directly measured, which had more effect on I was the density difference between crystalline and amorphous zones, pc−pa; the main part of the reduction in I was therefore attributed to the compensation of this difference [4]. By combining the low-angle X-ray scattering with a fibre shaded with iodine [5], we tried to verify the earlier conclusion that the intrafibrillar amorphous zones become denser, and to evaluate their density. The term “intrafibrillar” is defined as being the zones which directly affect I by their density and dimensions. The remaining unordered zones of the polymer were named interfibrillar.

Structure, mechanical, and tribological characteristics of polyurethane modified with nanodiamonds

The effect of modifying additives based on detonation nanodiamonds on the tribological characteristics of polyurethane rubber is studied. Introduction of modifying additives based on detonation nanodiamonds (0.5 wt %) leads to a marked improvement in the antifriction and wear-resistance characteristics under conditions of boundary sliding friction for steel and for lubrication with water. The attained tribological characteristics (total energy loss for friction, weight loss of polymer during tribological contact, maximum admissible working pressure) are well (∼300%) above the corresponding characteristics of foreign analogs. Changes in the tribological characteristics of the formed nanocomposite material are observed, but the elastic and strength characteristics remain unchanged.

Investigation of changes in supramolecular organization of oriented films of low-density polyethylene in the process of reorientation

Abstract Changes in supermolecular organization (SMO) of oriented films of low-density polyethylene were investigated by small (SAXS) and wide (WAXS) angle x-ray scattering. The films were oriented at different angles α with respect to the initial orientation. The temperatures of the initial orientation (T1) and of reorientation (T2) were varied as follows: (1) T1 > T2 (T1 = 85°C, T2 = 20°C); (2) T1-T2 = 85°C; (3) T1 = T2 = 20°C. In all cases, at relatively high α, reversible skewing of crystallites with initial SMO occurs in the beginning of deformation and, after the critical angle of skewing is attained, the crystallites are destroyed and a new SMO is formed. At T1 = T2 the initial and the new SMO are not distinguished by x-ray diffraction patterns and changes in the latter correspond to a simple rotation of the structure in combination with a relatively small skewing of the crystallites. The first variant of the relationship, T1 > T2, yields the most extensive information. In this case the initial and...

X-ray diffraction analysis of C60 fullerene powder and fullerene soot

C60 fullerene powder and fullerene soot are examined by the method of small-angle X-ray diffraction. Small-angle diffraction patterns constructed in the Guinier coordinates make it possible to find the radii of inertia of scattering elements. The small-angle diffraction scattering findings agree well with large-angle X-ray diffraction data.

Express investigations of wear processes by means of cylindrical counterbodies. Part I: Calculations and technique

Abstract Linear wear intensity Ih was calculated for a fixed cylindrical body which is initially in contact along a single line with another cylindrical body rotating at a constant velocity. The equation I h = Zhf(L) L f (L) was obtained for Ih, where h is the depth of the wear groove formed along the path L, f(L) and f(L) are the instantaneous and average friction coefficients, respectively, and Z is a constant in which the shape of the counterbodies is taken into account. The validity of the energy wear concept was assumed in the calculation. On the basis of these calculations a rapid technique for studying wear processes was proposed. In this technique the usual preliminary formation of the wear groove is absent. The technique was used for testing different commercial materials (steels, bronze and brass) lubricated with different oils. The tribological characteristics of the materials, determined by proposed method, are in agreement with literature data.

Variations in the structure of aromatic solvents under the influence of dissolved fullerene C70

Dilute solutions of the C70 fullerene (at concentrations from 0.0001–0.0005% to a few hundredths of a percent) in benzene, toluene, and p-xylene are investigated using small-angle and wide-angle X-ray diffraction. It is revealed that an increase in the C70 fullerene concentration leads to a nonmonotonic shift of the small-angle X-ray diffraction patterns along the intensity axis: the intensity first decreases, reaches a minimum, and then increases. The wide-angle X-ray diffraction patterns of all the solutions under investigation exhibit two halos: as the fullerene concentration in the solution increases, the intensity of the first halo increases, whereas the intensity of the second halo decreases. The variations observed in the X-ray diffraction patterns of the fullerene solutions are interpreted in terms of structuring of the solvents, i.e., the formation of a specific order on the molecular and supramolecular levels. The X-ray diffraction data are in good agreement with the nonmonotonic concentration dependences of the density of the fullerene solutions in aromatic solvents. A structural interpretation of the initial decrease in the density of the fullerene solutions is proposed.

Carrying capacity of polymers and polymeric composites in water-lubricated friction against metals

On the basis of the authors’ numerous publications in the field over many years, the paper presents a retrospective review of the influence of various factors on the carrying capacity of a number of polymers and polymeric composites at boundary sliding against metals (steels and bronzes of various grades) under water lubrication.

Trapping of solvent by a C60 fullerene film

Mass spectrometry was used over a wide temperature range to compare processes of solvent (toluene) release and desorption of C60 fullerene molecules from a fullerite film formed from solution on an oxidized metal substrate. It is shown that toluene is strongly retained in the fullerite film and that it is almost impossible to remove the toluene from the film without damaging its structure. Quantitative characteristics of the toluene retention and trapping effect are determined.