Structure and tribological behavior of nanocomposite C-Ti-WSe x coatings

Nanocomposite thin C-Ti-WSe _x coatings, which contain antifriction (WSe _x and amorphous carbon a-C) and hard (β-WC and TiC) components, are produced by pulsed laser deposition. In order to improve the tribological characteristics of the WSe _x phase and to transform the structural state of the a-C matrix, alloying with titanium is used. The characteristics of the coatings are determined using the sliding of a steel ball at an increased humidity. A comparison of the characteristics of a composite C-Ti-WSe _x coating and a carbon coating alloyed with titanium (a-C(Ti)) shows that the modification of the a-C matrix by introducing the WSe _x phase leads to an increase in the coefficient of friction from 0.05 to 0.2; the wear of the composite coating is approximately six times higher than that of the a-C(Ti) coating. Possible solutions for improving the tribological characteristics of the composite C-Ti-WSe _x coating in humid air are considered.     

Efficient Arrangement of Blanks Made of Oxide Ceramics in the Course of Jet-Abrasive Machining

Refractories and Industrial Ceramics - We perform the experimental investigation of the influence of arrangement of blanks made of oxide ceramics in the chambers of sandblasting installations on...     

Development of residual cutting tool life prediction algorithm by processing on CNC machine tool

The paper is dedicated to the decision of a problem of cutting tool diagnostics and working out of a remaining cutting tool life prediction algorithm. The example for practical realization of such algorithm on the CNC machine tool by machining under specified conditions is given. The question of working error compensation by means of corrective adjustment is considered.     

Structural modification and tribological behavior improvement of solid lubricating WSe x coatings during pulsed laser deposition in buffer He-Gas

Thin film, solid lubricating WSe _x coatings were deposited at room temperature on a steel substrate with a titanium underlayer by pulsed laser deposition (PLD). Two modes of PLD were investigated, i.e., the PLD under vacuum conditions and the PLD in a buffer gas (helium) at a pressure of 2–10 Pa. Gas was used to slow down the laser-induced atomic flux and to modify thus the conditions of the coatings growth. At a pressure ～8 Pa, gas reduced the effectiveness of Se preferential sputtering by atomic flux, which resulted in the formation of coatings with a stoichiometric composition (x ≈ 2). The structure of the coatings was characterized by a greater degree of the perfect organization of atoms in the nanophase laminar packaging and reduced internal stresses. Studies by the ball-on-disk tests in humid air showed that the modification of the structure and the chemical composition of the coatings had a significant effect on their tribological behavior. Vacuum-deposited coatings fractured relatively quickly due to the cracking and delamination from the substrate surface along the sliding track. When the coatings deposited in helium were tested, wear by layer-by-layer removal was dominant, so the adhesive fracture was only observed in the local parts of the track. The simulation of the laser vapor deposition in the vacuum and in the buffer gas was performed. Likely factors that improve the tribological properties of the coating during deposition in the buffer gas were disclosed.     

Combined Analysis of the Stress-Strain State of Al2O3–TiC Ceramics Surface Layer with AlN and TiN Coatings

Refractories and Industrial Ceramics - The influence of AlN and TiN coatings on the stress–strain state of the surface layer on Al2O3–TiC ceramics under the influence of a combined load...     

The formation of a hybrid structure from tungsten selenide and oxide plates for a hydrogen-evolution electrocatalyst

It has been found that the pulsed laser deposition of a thin tungsten selenide film, followed by thermal treatment at 550°C in an Ar + O₂ mixture of gases, results in the formation of a hybrid structure that is made up of ultrathin WSe₂ and WO_3–y platelets. The structural and size characteristics of the nanoplatelets deposited on microcrystalline graphite provide the effective hydrogen evolution reaction in a 0.5 M H₂SO₄ solution, with the cathode current made about seven times higher at a potential of–100 mV and the slope of the Tafel characteristic reduced from 340 to 90 mV/dec.