Solid State Phenomena Vol. 355

Abstract: The influence of the initial shape of graphite powder and Ni content on the structure and properties of the nickel-graphite powders and plasma-sprayed coatings is investigated. The irregularly and spherically shaped graphite powders were produced by mechanical crushing and mechanical crushing with rolling, respectively. It is shown, that spherically shaped graphite powder has advantages in flowability and better deposition of Ni layer. The nickel-graphite core-shell powders with 50 and 75 wt.% Ni content were used to deposit coatings by plasma spraying. The composition, structure, and hardness of the nickel-graphite coatings were studied.

Abstract: The composition, structure, and tribological characteristics at 20 °C and 500 °C of coatings obtained by the vacuum arc deposition method using a MAX phase Ti₂AlC based cathode were investigated. These characteristics were compared to those of titanium nitride coating. It was shown that at a potential of -50 V, a composite coating of TiC and Ti₃AlC phases forms. Meanwhile, at a potential of -100 V, a composite consisting of TiC and α-Ti is formed. At 20 °C, the friction coefficient and specific wear rate of these coatings in contact with a ball made of ShKh15 steel under a load of 2 N are comparable to those of TiN coating. At 500 °C, the wear resistance of the composite (TiC+α-Ti) coating is twice as high as that of TiN coatings. There was no clear correlation between microhardness and the tribological characteristics of the coatings.

Abstract: The plasma sprayed bronze coatings are widely used for repairing of plain bearing used in different applications. This type of coating was not deeply analyzed in state-of-art publications. In presented article we fill this gap in the case of plasma spraying process. The influence of power current (300/500/700A) and hydrogen flow (0/4/8 NLPM) on microstructure and thickness of aluminium bronze-polyester coating was investigated. The Thermico A60 plasma torch was used for thermal spray process of coating on flat carbon steel samples (grade S355). The Metco 604NS was sprayed with 20g/min powder feed rate. The obtained results showed the presence of local large pores formed by burning of polyester in plasma plume. This gap makes role of oil pockets in bearings. The obtained coatings were characterized by large deviation in thickness in range 200-350 micrometers. It might be concluded that in requires additional milling process after deposition.

Abstract: The essential task of modern industry is to increase the reliability and durability of products. One of the promising ways to increase the products operational durability is the ceramics and cermets powders functional coatings application to the working surfaces by the method of high-speed multi-chamber detonation spraying. The objective of the given paper is to determine the regularities of the influence of structural-phase features in the formed material of functional cermets coatings of metal parts on their strength characteristics and crack resistance, while taking into account structural criteria that will provide the required set of strength and crack resistance properties. The method for deep and detailed analysis of the structure features, morphology and distribution of phase particles, their stoichiometric composition, substructure parameters, dislocation density in the coating material obtained due to multi-chamber detonation spraying has been developed in this paper. The research of detonation coating material was carried out using transmission electron microscopy (TEM) on JEM-200CX instrument (produced by JEOL company) with the accelerating voltage of up to 200 kV. The prospects of using the method of multi-chamber detonation spraying on various materials (steel, copper, aluminum, titanium) and alloys are shown on the basis of the research results. A number of composite coatings made of aluminum and zirconium ceramics; chromium, tungsten carbides have been obtained. It has been defined that changes occur in the ratio of the following parameters: microhardness, pore volume fraction, phase composition, distribution of dispersed phases, grain, subgrain, dislocation structures, etc, under different processing modes in the surface layers and corresponding change in the modes of detonation spraying.

Abstract: Coordination polymers, a broad class of porous hybrid materials resulting from the connection of metal ions with organic ligands, showcase enduring porosity, well-organised crystalline structures, and open metal active sites that augment their metal ions' redox activity. This investigation focuses on examining a nanocomposite composed of cobalt carbide/reduced graphene oxide (Co₃C/rGO) prepared through the copolymer method, serving as an electrode material for supercapacitor devices. The nanocomposite's structure and hollow cubic morphology were confirmed through X-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopy (FESEM) analysis. Electrochemical properties were thoroughly assessed using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge in 6M KOH with a voltage window of 0 V to 0.5 V. The Co₃C/rGO electrode exhibited notable electrochemical performance, displaying a specific capacitance of 486.6 F g^-1 at 1 mV s^-1 and a low internal resistance of 0.58 Ω, surpassing existing literature due to its porous morphology. Additionally, to evaluate the nanocomposite's cycling stability, 5000 charge/discharge cycles were conducted, revealing a capacitive retention of 82% of its original capacitance after 5000 cycles. This underscores its excellent long-term durability as a high-performance material for supercapacitor applications.

Abstract: The electromechanical performances of dielectric elastomers were investigated after the incorporation of the confined permittivity enhancing fillers in bacteria cellulose (BC) into polydimethylsiloxane (PDMS) films. The purpose of this study is to investigate the capability of BC as a confinement matrix for the permittivity enhancing fillers to overcome the low relative permittivity and at the same time to increase the softness of the PDMS films. The metal oxide and silicone oil were confined in BC before being physically mixed with PDMS at different percentages. The results showed that the confined TiO2-BC increased the relative permittivity and at the same time maintained the softness of the PDMS films to some extent. In addition to that, by adding confined silicone oil-BC into the PDMS films, this PDMS based dielectric elastomer (DE) becomes even softer.