TiC/Ti3AlC2–Co plasma-sprayed coatings with excellent high-temperature tribological properties

The tribological properties of complex polymeric materials, which include epoxy and polyester resins, two hardeners and two microdispersed fillers: mica-muscovite, copper (II) oxide, were investigated in the work. The results of the testing of specimens at dry friction and in the lubricant were analyzed. It is proved, that the antifriction properties of the composite depend on its composition, formation technology and testing conditions. It has been experimentally determined, that the material which was tested in the lubricating environment – Im = 0.25–0.30 mg/km, f = 0.03–0.04, differs with the improved indexes of wear rate and friction coefficient. As a result of the analysis of investigated microsurfaces studied by optical and electron microscopy, the phase heterogeneity of the composite material system was identified. It contributes to the reduction of the running-in distance of the specimen, and indicates the uniform distribution of the filler particles on the surface, has been found. The elemental composition of the compound was determined, which indicates the direct involvement of fillers in the process of friction. A change in the ratio of atoms on the specimen surface before and after the test was found. The results of the study of the surface in the phase contrast mode correlate with the results of the data obtained by electron microscopy.

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Investigation of Tribological Properties of Two-Component Bidisperse Epoxy-Polyester Composite Materials for Its Use in the Friction Units of Means of Sea Transport

The work presents an analytical study of “crosshead-slide rail” wear effect on stress state of a double piston pump’s rod. The authors proposed an engineering model of pump’s rod stress state and analytically analyzed a pump rod's stress state caused by wear of the “crosshead-slide rail” pair. It was stated, that wear values according to regulations and directive documents can refer to significant values of rod’s residual stresses. The numerical validation of the obtained results was carried out on for drill pump rods, including reinforced functional coatings.

https://iopscience.iop.org/article/10.1088/1742-6596/1741/1/012039/pdf

Analytical study of “crosshead – slide rail” wear effect on pump rod stress state

The corrosion resistance and hydroabrasive resistance of the developed epoxy composite coatings are investigated in this paper. The analysis of the penetration index change after τ = 50–150 days of immersion in a water medium and 10% sulfuric acid solution is carried out. The optimal ratio of the modifier and nanodispersed (Si3N4, Al2O3, AlN, and TiN) and fibrous (viscose, polyamide, matka silk, rong, and cashmere) fillers in the epoxy binder is determined. It was allowed to slow down the process of electrochemical reaction on the metal surface. The penetration of aggressive media in such a coating during the time t = 150 days is 0.8–2.8%. It is 1.5–2 times lower than the similar indexes of the initial epoxy matrix. The rational combination of the fibrous filler (wool, acrylic PAN, and cashmere), modifier, and nanodispersed (Si3N4, AlF3, IH, and ZrH) filler in the epoxy binder is found, which allows to provide optimum indexes of wear rate. The wear rate under the action of a hydroabrasive of such a coating is I = 0.20%, which is 4 times lower than the similar indexes of the initial epoxy matrix. The wear mechanism of such coatings is caused by the physical and mechanical processes of microcutting and plastic deformation of the surface layer of the material.

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The Use of Complex Additives for the Formation of Corrosion- and Wear-Resistant Epoxy Composites

Textured surfaces with partially regular micro relief (PRMR) are reported to be an effective means to control lublication. It was found they are good wear debris trap and suppliers of lubricant directly to the actual friction area. Their tribological properties depend on the clearance between mating surfaces, relative slip speed, direction of motion. These parameters change the lubrication regime, and vice versa changing geometry of PRMR it is possible to predict and control lubrication regime for given conditions. Application of micro textured surface is prospective for high precision sliding units – valve slides of oil and hydraulic systems, faces of gear pump gears, ring-to-cylinder interface of aircraft reciprocating engines etc. providing high service life. On other side, changing texture parameters it is possible to stop the leakage of fluid through the gap, what may be efficiently utilized in aircraft non-contacting mechanical (hydrodynamic and hydrostatic) seals of gas compressors and gear mechanisms. This paper discloses some peculiarities of transition lubrication regimes for textured surfaces in lubricated contact.

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Features of transition modes of friction surfaces with partially regular microrelief

The paper considers the possibility to improve the quality of a plasma coating by means of a laser treatment in the melting and thermal cycling modes. This method provides stronger adhesion of a coating to its base material as well as higher wear resistance. The regularities of the laser treatment in the melting and thermal cycling modes are determined, and a connection between the technological parameters and the quality characteristics is shown.

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Improvement of the quality of TiC-Co system plasma coating by laser treatment

The results of research related to the influence of partially regular microrelief parameters on the adhesion component of the friction factor under boundary lubrication are presented. It has been shown that micro grooves are effective under boundary friction on precision surfaces with low roughness when lack of film and probability of seizure appear. The deformation component of the friction force of surfaces with micro grooves has been studied. The time of micro running-in was the key factor while assessing the dependence of the deformation component on friction when taking into account the depth of micro grooves and their relative area. The research was conducted using a tribometer according to the friction model entitled “shaft & flexible steel tape”.

The friction mechanism between surfaces with regular micro grooves under boundary lubrication

A complex study of the properties and characteristics of discrete structure surfaces with mechanically formed dimples has been carried out. It is shown that the combination of scientific research on friction and wear processes in different scientific and engineering areas, such as mathematical statistics, mechanics of contact, physics of surfaces and magnetism and hydrodynamics, provides a deeper explanation of the processes that take place on discrete surfaces of contact elements.

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Andrii Kryzhanovskyi

Papers

Improvement of the quality of TiC-Co system plasma coating by laser treatment

The friction mechanism between surfaces with regular micro grooves under boundary lubrication

System analysis of the properties of discrete and oriented structure surfaces

Features of transition modes of friction surfaces with partially regular microrelief