Electrochemical Characteristics of PEO Treated Electric Arc Coatings on Lightweight Alloys

2010 ◽  
Vol 138 ◽  
pp. 55-62 ◽  
Author(s):  
H.M. Nykyforchyn ◽  
V.I. Pokhmurskii ◽  
M.D. Klapkiv ◽  
Mykhajlo M. Student ◽  
Juliet Ippolito
Keyword(s):  
Corrosion Resistance ◽  
Ceramic Coatings ◽  
Electric Arc ◽  
Arc Spraying ◽  
Oxide Ceramic ◽  
Electrochemical Characteristics ◽  
Ti Alloys ◽  
Oxide Phases ◽  
Oxide Ceramic Coatings ◽  
Plasma Electrolytic

The complex technology of the surface treatment of Al, Mg, Ti alloys for size reconstruction and strengthening is presented herein. This consists of electric arc spraying of aluminum alloys or powder wire in an aluminum shell and then treatment with plasma electrolytic oxidation (PEO). Once treated, oxide-ceramic coatings maintain extreme hardness, durability and resistance to wear. At the same time their corrosion-resistant properties are also significant. Dynamic potential dependences were studied for electric arc Al coatings and PEO treatments on Al, Mg, Ti alloys and corrosion currents were analyzed for exposure to a corrosive environment for a period of from 1 hour to 30 days. It was established that PEO treated coatings on Al alloys have a higher corrosion resistance than untreated sprayed coatings. In Mg alloys, an intermediate layer of aluminum electric arc coating between the substrate and PEO-treated coating is necessary in order to ensure high corrosion resistance. This is due to the specifics of the formation of the MgO and Al2O3 oxide phases in the plasma discharge channels. At the same time Al coatings on Ti alloys, including those of post-PEO treatment, were characterized as having lower corrosion resistance within the range of electrode potential from corrosion potential up to repassivation potential, than were untreated Ti-alloys. Yet it was found that the corrosion resistance of PEO treated coatings increases at higher anode potentials. Under cathode polarization the hydrogen discharge is less likely to occur on PEO-coatings than on untreated Ti alloys which more effectively prevents hydrogenation.

Simultaneous Reduction of Wear and Corrosion of Titanium, Magnesium and Zirconium Alloys by Surface Plasma Electrolytic Oxidation Treatment

2008 ◽  
Vol 38 ◽  
pp. 27-35 ◽  
Author(s):  
H.M. Nykyforchyn ◽  
V.S. Agarwala ◽  
M.D. Klapkiv ◽  
V.M. Posuvailo
Keyword(s):  
Corrosion Resistance ◽  
Plasma Electrolytic Oxidation ◽  
Synthesis Method ◽  
Zirconium Alloys ◽  
Ceramic Coatings ◽  
Oxide Ceramic ◽  
Wear And Corrosion ◽  
Electrolytic Oxidation ◽  
Wear And Corrosion Resistance ◽  
Plasma Electrolytic

Titanium, magnesium and zirconium alloys are widely used in industrial applications, which require high wear and corrosion resistance. However current methods of improving these properties often do not satisfy the requirements of service and functional properties. An alternative approach is the application of oxide-ceramic coatings using high temperature process. The coatings are applied by spark discharge plasma in the metal-electrolyte system at high voltages - PEO (plasma electrolytic oxidation) as an oxide synthesis method. This method has shown good results for aluminium alloys and with good prospects to be used for titanium, magnesium and zirconium alloys. Development of PEO technology to improve the wear and corrosion resistance of titanium, magnesium and zirconium alloys is discussed in this paper. It describes the methods for obtaining the required layer-thickness for a specified hardness, porosity, wear and corrosion resistance, sets up the optimal process parameters (voltage/current) by taking the relation of anodic to cathodic currents into account, and establishing the electrolyte content of different dopants.

Investigation of Internal Stresses in Thin Layer Oxide Coatings on Aluminum Alloys

2019 ◽  
Vol 968 ◽  
pp. 153-160 ◽  
Author(s):  
Yuri A. Kuznetsov ◽  
Aleksandr V. Kolomeichenko ◽  
Vladimir V. Goncharenko ◽  
Igor N. Kravchenko
Keyword(s):  
External Action ◽  
Ceramic Coatings ◽  
Experimental Investigations ◽  
Internal Stresses ◽  
Oxide Ceramic ◽  
Oxide Coatings ◽  
Properties Of Coatings ◽  
Oxide Ceramic Coatings ◽  
Plasma Electrolytic ◽  
Aluminum Surfaces

Among physical and mechanic properties of coatings the internal stresses are of special interest. Internal stresses include stresses which exist and are counterbalanced within a rigid body in cases when there is no external action which caused them. In coatings obtained on the basis of nickel, chrome they can decrease the adhesive strength, cause cracking, peeling, anticorrosion properties deterioration. But the definite level of internal stresses leads to increase of hardness and coatings wear resistance and also facilitates porous coatings obtaining. The results of theoretical and experimental investigations of the internal stresses that appear in oxide ceramic coatings formed by plasma-electrolytic oxidation (PEO) on aluminum surfaces are presented.

scholarly journals Introduction to Plasma Electrolytic Oxidation—An Overview of the Process and Applications

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 628 ◽  
Author(s):  
Frank Simchen ◽  
Maximilian Sieber ◽  
Alexander Kopp ◽  
Thomas Lampke
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Strong Electric Field ◽  
Ceramic Coatings ◽  
Substrate Material ◽  
Oxide Ceramic ◽  
Plasma State ◽  
Electrolytic Oxidation ◽  
Oxide Ceramic Coatings ◽  
Micro Arc Oxidation ◽  
Plasma Electrolytic

Plasma electrolytic oxidation (PEO), also called micro-arc oxidation (MAO), is an innovative method in producing oxide-ceramic coatings on metals, such as aluminum, titanium, magnesium, zirconium, etc. The process is characterized by discharges, which develop in a strong electric field, in a system consisting of the substrate, the oxide layer, a gas envelope, and the electrolyte. The electric breakdown in this system establishes a plasma state, in which, under anodic polarization, the substrate material is locally converted to a compound consisting of the substrate material itself (including alloying elements) and oxygen in addition to the electrolyte components. The review presents the process kinetics according to the existing models of the discharge phenomena, as well as the influence of the process parameters on the process, and thus, on the resulting coating properties, e.g., morphology and composition.

Protective and Thermophysical Characteristics of Plasma-Electrolytic Coatings on the Ultra-Light Magnesium Alloy

2021 ◽  
pp. 1-15
Author(s):  
Sergey Grigoriev ◽  
Igor Kondratsky ◽  
Boris Krit ◽  
Valery Ludin ◽  
Varvara Medvetskova ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Thermal Diffusivity ◽  
Magnesium Alloys ◽  
Ceramic Coatings ◽  
Specific Electrical Conductivity ◽  
Technological Parameters ◽  
Thermophysical Characteristics ◽  
Light Alloy ◽  
Plasma Electrolytic ◽  
Integral Assessment

Abstract Magnesium alloys are now widely used for various purposes due to their unique properties despite the significant disadvantage associated with low corrosion resistance. The plasma-electrolytic oxidation (PEO), which allows the formation of ceramic coatings on the surface of magnesium alloys, is the most advanced and effective method for their protection. But firstly, PEO process of magnesium alloys has some difficulties, and secondly, PEO coatings affect the thermophysical characteristics of the modified materials, in particular they reduce thermal diffusivity. The presented work is devoted to the development of the technological parameters for formation of protective coating on the ultra-light alloy Mg-8Li-1Al-0.6Ce-0.3Y by the PEO method. The results analyses of electrolytes acidity and specific electrical conductivity before and after PEO process and also investigation data of the coatings structure and surface morphology are presented. An integral assessment of the ability of thermal diffusivity and corrosion resistance of the modified alloy was made. Studying of protective and thermophysical characteristics of the obtained coating showed that it provides a sufficiently high corrosion protection, despite the relatively small thickness, and the presence of pores and slightly (not more than 5%) reduces the thermal diffusivity of the magnesium ultra-light alloy.

The Growth Process of the PEO Films under Escalating Voltage Waveform

2011 ◽  
Vol 239-242 ◽  
pp. 720-723
Author(s):  
Li Wang ◽  
Wen Fu ◽  
Li Chen
Keyword(s):  
Corrosion Resistance ◽  
Growth Process ◽  
Ceramic Coatings ◽  
Voltage Waveform ◽  
Potentiodynamic Polarization Curves ◽  
Initial Stage ◽  
Electrolytic Oxidation ◽  
Superior Corrosion Resistance ◽  
Plasma Electrolytic ◽  
Peo Coatings

In order to get a clear picture for describing the growth process of plasma electrolytic oxidation coatings under escalating voltage waveform, the characteristics of PEO coatings formed at different reaction stages were systemically investigated. The morphology and corrosion resistance of the films were studied by scanning electron microscope and potentiodynamic polarization curves. The uniform, semi-transparent and better corrosion resistance of the oxide films on the magnesium electrode surface were formed owe to the extended anodizing time at the initial stage under escalating voltage mode. After sparking occurred, generated ceramic coatings were brokedown, melted, cooled and solidified continuously, so the ceramic coatings were uniform and dense. It also exhibited superior corrosion resistance.

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