An investigation of ceramic coating growth mechanisms in plasma electrolytic oxidation (PEO) processing
TL;DR: In this paper, the authors used optical emission spectroscopy (OES) to follow the microdischarges and substrate and electrolyte elements present in the plasma discharge during the coating growth, and to determine plasma electron temperatures.
About: This article is published in Electrochimica Acta.The article was published on 2013-12-01. It has received 354 citations till now. The article focuses on the topics: Coating & Plasma electrolytic oxidation.
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TL;DR: In this article, a comprehensive review around mechanisms of PEO coatings fabrication and their different properties is provided, and the coatings properties, affecting parameters and improvement strategies are discussed, including corrosion resistance of coatings, important factors in corrosion resistance and methods for corrosion resistance improvement.
349 citations
TL;DR: In this paper, the influence of the electrolyte, process parameters, pretreatment and post-treatment on the coating characteristics (surface micrograph, adhesion strength and biological compatibility etc.) is detailed.
243 citations
TL;DR: In this paper, a review described a couple of the scientific principles including transient discharge behavior at breakdown, nucleation and growth of inorganic layer, and electrophoresis for incorporating inorganic particle.
212 citations
TL;DR: In this article, nano-and micro-sized SiO2 particles were in-situ incorporated into phosphate-based coatings and the effect of these particles on the microstructure, composition and properties of the coatings was investigated.
196 citations
TL;DR: In this paper, a brief overview of surface engineering of the Ti-based alloys from the perspective of electrochemistry is given, which mainly focuses on three major electrochemical techniques: low voltage anodization, micro-arc oxidation, and electrodeposition.
154 citations
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TL;DR: The physical and chemical fundamentals of plasma electrolysis are discussed in this article, and the equipment and deposition procedures for coating production are described, and the effects of electrolyte composition and temperature on ignition voltage, discharge intensity and deposited layer thickness and composition are outlined.
Abstract: This paper overviews the relatively new surface engineering discipline of plasma electrolysis, the main derivative of this being plasma electrolytic deposition (PED), which includes techniques such as plasma electrolytic oxidation (PEO) and plasma electrolytic saturation (PES) processes such as plasma electrolytic nitriding/carburizing (PEN/PEC). In PED technology, spark or arc plasma micro-discharges in an aqueous solution are utilised to ionise gaseous media from the solution such that complex compounds are synthesised on the metal surface through the plasma chemical interactions. The physical and chemical fundamentals of plasma electrolysis are discussed here. The equipment and deposition procedures for coating production are described, and the effects of electrolyte composition and temperature on ignition voltage, discharge intensity and deposited layer thickness and composition are outlined. AC-pulse PEO treatment of aluminium in a suitable passivating electrolyte allows the formation of relatively thick (up to 500 μm) and hard (up to 23 GPa) surface layers with excellent adhesion to the substrate. A 10–20 μm thick surface compound layer (1200HV) and 200–300 μm inner diffusion layer with very good mechanical and corrosion-resistant properties can also be formed on steel substrates in only 3–5 min by use of the PEN/PEC saturation techniques. Details are given of the basic operational characteristics of the various techniques, and the physical, mechanical and tribological characteristics of coatings produced by plasma electrolytic treatments are presented.
2,552 citations
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13 Nov 1997TL;DR: The diagnosis of plasmas using spectroscopic observations has its origins in various older disciplines, including astronomy and discharge physics as mentioned in this paper, and the need for non-interfering diagnostics arose and spectroscopy was applied to determine the physical state and chemical abundance of the studied.
Abstract: The diagnosis of plasmas using spectroscopic observations has its origins in various older disciplines, including astronomy and discharge physics. As laboratory plasma physics evolved from low-density, low-temperature discharges to higher energy density plasmas, the need for non-interfering diagnostics arose and spectroscopy was applied to determine the physical state and chemical abundance of the plasmas studied.
1,120 citations
1,019 citations
TL;DR: In this article, the effects of process parameters (i.e., current density and treatment time) on the plasma discharge behavior during the PEO treatment were investigated using optical emission spectroscopy (OES) in the visible and near ultraviolet (NUV) band (285-800 nm).
Abstract: In this study, a plasma electrolytic oxidation (PEO) process was used to produce oxide coatings on commercially pure aluminium (1100 alloy) at a pulsed dc power mode. The effects of process parameters (i.e. current density and treatment time) on the plasma discharge behaviour during the PEO treatment were investigated using optical emission spectroscopy (OES) in the visible and near ultraviolet (NUV) band (285–800 nm). The elements present in the plasma were identified. Stark shifts of spectral lines and line intensity ratios were utilized to determine the plasma electron concentrations and temperatures, respectively. The plasma electron temperature profile, coating surface morphology and coating composition were used to interpret the plasma discharging behaviour. The different coating morphologies and compositions at different coating surface regions are explained in terms of three types of discharge, which originate either at the substrate/coating interface, within the upper layer, or at the coating top layer. The high spike peaks on the plasma intensity and temperature profiles corresponded to discharges originated from the substrate/coating interface, while the base line and small fluctuations were due to discharges at the coating/electrolyte interface.
461 citations
TL;DR: In this article, a phenomenological mechanism for the formation of the alumina-based ceramic coatings during the microarc oxidation (MAO) process has been proposed and the surface features of the coatings were studied using scanning electron microscopy.
Abstract: Thick alumina coatings were synthesized on 7075 Al-alloy substrates through the microarc oxidation (MAO) route. Different oxidation times namely 1, 3, 5, 10, 20 and 30 min were employed and the coated samples were subjected to coating thickness and surface roughness measurements. Phase composition of the surface layers of the coatings was evaluated through X-ray diffraction. In addition, the surface features of the coatings were studied using scanning electron microscopy. Influence of coating time on the kinetics of coating formation, surface roughness, microhardness, number and size of the microarc discharge channels was investigated. On the basis of the experimental results, a phenomenological mechanism for the formation of the alumina-based ceramic coatings during the MAO process has been proposed.
444 citations