This paper reviews the present understanding of electrolytic plasma processes (EPPs) and approaches to their modelling. Based on the EPP type, characteristics and classification, it presents a ...generalised phenomenological model as the most appropriate one from the process diagnostics and control point of view. The model describes the system ‘power supply–electrolyser–electrode surface’ as a system with lumped parameters characterising integral properties of the surface layer and integral parameters of the EPP. The complexity of EPPs does not allow the drawing of a set of differential equations describing the treatment, although a model can be formalised for a particular process as a black box regression. Evaluation of dynamic properties reveals the multiscale nature of electrolytic plasma processes, which can be described by three time constants separated by 2–3 orders of magnitude (minutes, seconds and milliseconds), corresponding to different groups of characteristics in the model. Further developments based on the phenomenological approach and providing deeper insights into EPPs are proposed using frequency response methodology and electromagnetic field modelling. Examples demonstrating the efficiency of the proposed approach are supplied for EPP modelling with static and dynamic neural networks, frequency response evaluations and electromagnetic field calculations.
•Comprehensive classification of electrolytic plasma surface treatments•Generalised phenomenological model of electrolytic plasma processes•Examples of phenomenological modelling for different processes•Perspectives on development of smart electrolytic plasma technologies
The modified technology for strengthening the surface layer of low-carbon steel for machine components by electroplasma processing is proposed. This technology is to be used as an alternative ...carburizing method with subsequent hardening. The developed technology of strengthening by the proposed method is based on the author’s invention. The parameters of this process are given, resulting in a thickness of the reinforced surface layer of 1000 µm to 1700 µm. An increase in microhardness of 1.5 to 2 times (compared to the initial state) was observed. With hardening, chemical modification of the material’s surface layer occurs. The microstructure of the treated surface of the steel samples is characterised by a dark modified surface layer: a fine needle-like structure of martensitic origin under the dark layer transforms into an initial perlite-ferritic structure. The advantage of strengthening based on the electrolytic plasma processing consists of low energy consumption at high hardening speeds and the possibility of local processing of surface areas, especially large parts of complex shapes. In addition, the proposed surface treatment method using electrolytic plasma processing (EPP) not only achieves a smooth surface but also improves the service qualities of the components, specifically wear resistance.
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•We hope that this paper may serve as theoretical guidance for the further development and application of EPP.•EPP can efficient removal the surface scale with an appropriate process ...parameters.•EPP can dramatically increases the surface roughness by forming a layer of uniform micro multi-holes.•The micro-structure surfaces of high Nb-TiAl alloy were investigated using SEM, EDS, XRD, and 3D topography.
Metal surface modification by electrolytic plasma processing (EPP) is an innovative treatment widely commonly applied to material processing and pretreatment process of coating and galvanization. EPP involves complex processes and a great deal of parameters, such as preset voltage, current, solution temperature and processing time. Several characterization methods are presented in this paper for evaluating the micro-structure surfaces of Ti45Al8Nb alloys: SEM, EDS, XRD and 3D topography. The results showed that the oxide scale and other contaminants on the surface of Ti45Al8Nb alloys can be effectively removed via EPP. The typical micro-crater structure of the surface of Ti45Al8Nb alloys were observed by 3D topography after EPP to find that the mean diameter of the surface structure and roughness value can be effectively controlled by altering the processing parameters. The mechanical properties of the surface according to nanomechanical probe testing exhibited slight decrease in microhardness and elastic modulus after EPP, but a dramatic increase in surface roughness, which is beneficial for further processing or coating.
A thin diamond-like carbon film was deposited on Ni substrate by plasma electrolytic deposition in ethanol-water solution. The thickness of the deposited carbon film was measured about 40–60nm by ...using glow discharge optical emission spectroscopy and optical profilometer. The characterization of film structure by Raman spectroscopy showed the superposition of Raman features on a photoluminescence background because of low thickness of the deposited film. The surface enhanced Raman scattering technique by coating the carbon film with Au nanoparticles and high power laser in Raman spectroscopy was used as Raman intensity enhancer. Amplified Raman signals by using both techniques showed formation of diamond-like carbon film and various sp2 and sp3-bonded compositions on grain boundaries of nanostructure carbon coating. The Raman spectrum of the Au coated carbon film revealed an additional band at 2150cm−1, which is related to the carbyne structure whereas carbyne band could not be detected using high power laser. Comparison of Raman spectra at two wavelengths of 632.8 and 785nm showed changes in the intensity and position of Raman bands. Likewise, the 785nm laser wavelength excitation has sufficient energy to enhance the scattering from the grain boundary structures.
•The thin DLC film was successfully deposited on Ni substrate by the CPE process.•The SERS enhanced Raman revealed D and G bands and an additional band in 2150cm−1•The appearance of carbyne band (2150cm−1) by SERS is due to its low concentration.•High laser power Raman showed D and G bands and two bands in 1130 and 1430cm−1.•The presence of thin DLC film containing sp, sp2 and sp3 carbon bonding was proved.
As result of plasma-electrolytic nitrocarburizing 30CrMnSiA carbon steel (ferrite-perlite grade), there was a change in the elemental and phase composition, as well as the surface layer ...microstructure (40 ÷ 45 microns thick from the surface). A formation of Me23(CN)6 carbonitrides, FeN nitrides, Fe3C - (Fe,Cr)3C carbides and an increase in dislocation density within α–phase (tempered martensite crystallites), high-temperature lamellar martensite were observed. As a result of PEN / C exposure for 7min. at 750°C there is a reduction of friction coefficient and wear rate, what is connected with finely dispersed secondary phases FeN, (Fe, Cr)3C, Me23(C, N)6 formation. Thus there is an 2,5 ÷ 3,3 times increase in hardness of 30CrMnSiA carbon steel samples.
Coatings on Mg alloys were prepared using NaOH + Na2SiO3 as basic electrolyte containing electrolyte of Na2SiF6 or NaF. EPP treatment was carried out on AZ31 Mg alloys matrix under a hybrid voltage ...of AC of 200 V combined with DC of 260 V for 30 min. Structural and morphological analyses of ceramic coatings were analyzed by XRD and SEM. Wear and hardness of coatings were measured by pin-on disk test and Vickers hardness test. The coatings formed in Na2SiF6 and NaF electrolytes were mainly composed of MgO and Mg2SiO4. The measured micro-hardness of coating formed in Na2SiF6 electrolyte was found to be over HV 1100, while, coating formed in NaF electrolyte possessed micro-hardness of HV ∼900. These results show that the mechanical properties of AZ31B Mg alloys can be enhanced by the proper selection of electrolyte agent.
This work provides the results of research of the wear resistance of the surface of samples of low carbon structural of 18HN3MA-SH steel, subjected to electrolytic-plasma treatment by nitriding and ...carbonitriding. The effect of the structure on the surface wear resistance of steel is shown. Changes in abrasive wear and dry friction characteristics were studied depending on temperature and processing time. The results of studies of tribological tests show that after electrolytic-plasma nitriding, the wear resistance of steel 18HN3MA-SH increases by 1.5–2 times compared with the initial state. The observed effects can be explained by the flowing surface modification - the formation of a modified surface layer with the formation of hardening phases. The nature of changes in the surface roughness Ra of steel samples after cementation, carbonitriding and nitriding was studied.
The study of electrolytic-plasma jet polishing process was made using a high-speed camera. The process visualization allowed us to find optimization methods. Electrolytic-plasma jet polishing ...capabilities are demonstrated in terms of processing the additively manufactured gas turbine engine components with a high level of initial surface roughness and with internal cavities and channels.
In this study, electrolytic plasma processing (EPP) was employed for surface nitrocarburizing of AISI 1020 steel in a urea electrolyte, where the substrate samples were connected cathodically to a ...high-voltage DC current power supply. The structural, mechanical, wear and corrosion properties of the samples treated for 3–5min were investigated. The results show that the surface layers formed on the samples by this treatment at 220V have a ferritic nitrocarburizing characteristic which consists of a compound layer and diffusion zone. The surface layers of the treated samples at 240V consisted of a compound layer, martensitic layer and diffusion zone, respectively, which is a marker of austenitic nitrocarburizing. The compound layers formed at 220V and 240V consisted of ɛ-Fe2-3 (N,C) and γ′-Fe4 (N,C) phases. The hardness value of the compound layer on the substrate was about 930HV which was 4.5 times higher than that of the substrate. The thickness of the surface layer formed on the samples was a function of time and applied voltage. The wear and corrosion resistances of the samples were improved due to the surface treatment.
The welding characteristics of aluminum and aluminum alloy machine parts, as well as such welding methods as arc augmented laser welding, pulsed arc welding, gas tungsten pulsed arc butt welding, ...electrolytic plasma processing, friction stir welding are considered. The results of developments in this area are presented, the technical result of which is to improve the weld quality, the strength and durability of the welded joint.
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