Characterization of opportunity for upgrading of the system based on arc plasma torch for thermal spaying of ceramic materials, by means of use of fuel vortex intensifier. Part I: Thermodynamic modeling of the system efficiency parameters

One of the main trends in the field of improving the modern technologies of thermal spraying, including plasma one, for functional ceramic coatings formation is the reducing the energy consumption of the process. In this regard, one of the important directions for improving these technologies is the development of their new versions, using the principle of adding inexpensive fuel-oxidizer mixtures based on hydrocarbons with air. This type of plasma-fuel type of spraying will be promising for application at the present time, first of all, in order to obtain refractory functional coatings. For this purpose, we investigated the opportunity for upgrading an industrial unit/system for plasma spraying of ceramic powder materials with arc plasma torch of 25–40 kW power by the use of experimental variant of a fuel gas-vortex intensifier. The thermodynamic assessment of possible parameters of the generated mixed flow after the torch with this fuel intensifier was carried out to estimate the applicability of this system to optimize the spraying of oxide and carbide coatings (based on the examples of Al2O3, Cr3C2 and other powders). The analysis of possible parameters of the produced flow after the torch with intensifier was performed for the cases of main C–H–O–N–Ar–Me (Me = Al, Cr) systems and additional C–H–O–Al-system to assess the potential of this system to modify the technology of oxide and carbide ceramic coatings formation. New regimes, which were analyzed in our research as the simulants of Al2O3 spraying, surpass on calculated energy efficiency characteristics (by 10–20 %) one of the new prospective spraying methods with (СO2+СH4)-plasma, as well as the conventional method of powder heating during the spraying with N2-plasma. The case of our proposed fuel assisted process (FA-APS) with liquefied petroleum gas (LPG) fuel for the heating of ceramic powders (especially, Al2O3) demonstrates the advantage of the process (in particular, on the energy efficiencies and energy consumption) in a comparison with the conventional regimes of APS of the powders (in N2 plasma of the standard torch). For the variants of the FA-APS with Al2O3 and Cr3C2 feedstock powders it was established to be potentially possible to obtain (at the moderate values of total electric energy consumption for the torch and auxiliary equipment, – near 1.8 and 1.0 kWh/(kg of product)) such high level of the process productivity on the final product as approximately 17 and 28 kg/h, respectively; at the values of required power of the torch:  28.2 and  22.3 kW.

FEATURES OF THE STRUCTURAL PHASE STATE OF A FILM BASED ON A HIGH-ENTROPY AlNbTiZrCu ALLOY SYNTHESIZED BY DEPOSITION OF A MULTIELEMENT METAL PLASMA

В данной работе приведены результаты структурных исследований пленок толщиной до 5 мкм высокоэнтропийных сплавов системы AlNbTiZrCu . Пленки были синтезированы на металлических и металлокерамических подложках путем осаждения многоэлементной металлической плазмы, созданной электродуговым плазменно ассистированным одновременным независимым распылением нескольких катодов. Показано, что пленки являются слоистым материалом и имеют аморфнокристаллическую структуру. Установлено, что облучение пленок импульсным электронным пучком (18 кэВ, 20 Дж/см, 50 мкс, 3 имп., 0,3 с) сопровождается кристаллизацией материала. Показано, что в полученных пленках доминирует соединение состава AlNbTiZr с параметром решетки 0,32344 нм. На основе теоретических расчетов получены структурные данные кристаллической решетки AlTiZrNb и определены механические и термодинамические характеристики этого соединения. This paper presents the results of structural studies of films with a thickness of up to 5 microns of high-entropy alloys of the AlNbTiZrCu system. The films were synthesized on metal and cermet substrates by deposition of a multielement metal plasma created by electric arc plasma assisted simultaneous independent sputtering of several cathodes. It is shown that the films are a layered material and have an amorphous-crystalline structure. It was found that irradiation of films with a pulsed electron beam (18 keV, 20 J/cm, 50 gs, 3 imp., 0,3 s) is accompanied by crystallization of the material. It is shown that the resulting films are dominated by the compound of the AlNbTiZr composition with the lattice parameter of 0,32344 nm. On the basis of theoretical calculations, the structural data of the crystal AlTiZrNb lattice were obtained, mechanical and thermodynamic characteristics of this compound were determined.