Degradation Of Coatings Research Articles

Characterization of Biofilm Formation and Coating Degradation By Electrochemical Impedance Spectroscopy

Recent findings showed severe localized corrosion of submerged steel bridge piles in a Florida bridge and was associated with microbial activity in presence of marine foulers (Permeh et al, 2017;2018). Microbiologically Influenced Corrosion (MIC) can cause severe degradation of civil infrastructure. MIC has often associated with the formation of biofilm (including the complex interaction of microbe communities and development of extracellular polymeric substances (EPS)) that can influence the corrosion process either by creating oxygen differential aeration cells or generating acidic substances and cathodic reactant depending on the type of bacteria. Sulfate reducing bacteria (SRB) has received much attention in the study of MIC of steel developed in natural waters (Melchers and Wells, 2006; Castaneda and Benetton, 2008). Reactions associated with SRB causes cathodic depolarization of steel leading to the reduction of sulfates to sulfides and promoting steel corrosion (Borenstein,1994). Coatings have been developed to mitigate MIC and marine fouling. Studies have shown that coating blistering and disbondment can occur as a result of microbial attack due to the production of metabolites that degrade coating chemical and physical properties (Mansfield et al.,1998; Muntasser et al.,2002). Recent work evaluated the corrosion mitigation properties of a commercially-available, water-based, self-polishing, antifouling coating in environments that supported SRB as part of a larger research program to identify susceptibility of steel degradation in natural waters due to MIC (Permeh et al.,2019). In the work described here electrochemical impedance spectroscopy (EIS) was conducted to identify microbial activity and degradation of an antifouling coating. EIS was conducted on steel coupons coated with an antifouling coating (with and without coating defects) exposed to SRB inoculated modified Postgate B solution. The exposed coating surface area was ~19.6 cm2 and the coating thickness was ~0.17-0.35 mm. A three-electrode configuration was used for EIS measurements where the coated steel plate was the working electrode, an activated titanium rod was used as a reference electrode, and an activated titanium mesh was used as a counter electrode. EIS measurements were made at OCP condition with 10 mV a.c. perturbation voltage and at frequencies 1Mhz>f>1Hz. The measurements resulted in impedance with multiple loops in the Nyquist diagram (as shown in Figure 1) associated with processes relating to the polymeric coating, development of surface layers (biofilm), and the steel interface. Fitting of the impedance response to equivalent circuit analogs were made to identify coating characteristics and surface layer formation during the experimental exposure in inoculated and non-inoculated solutions. The results revealed near-ideal capacitance for the polymeric coating and a decrease in coating pore resistance. In samples inoculated with SRB, a second high frequency loop developed indicating formation of surface films. The results from EIS indicated degradation of the coating due to its self-polishing characteristics and that formation of surface layers associated with SRB can form as biocide components of the coating become depleted. Continued SRB growth may allow development of marine fouling if the antifouling coating components become less effective and allow possible shelter for SRB to promote MIC. Further work to verify these characteristics in field settings are in progress. References Borenstein, S. (1994). Microbiologically influenced corrosion handbook. Elsevier.Castaneda, H., & Benetton, X. D. (2008). SRB-biofilm influence in active corrosion sites formed at the steel-electrolyte interface when exposed to artificial seawater conditions. Corrosion Science, 50(4), 1169-1183.Mansfield, F., Lee, C. C., Han, L. T., Zhang, G., & Little, B. (1998). The Impact of Microbiologically Influenced Corrosion on Protective Polymer Coatings. University of Southern California Los Angeles Dept of Materials Science And Engineering.Melchers, R. E., & Wells, T. (2006). Models for the anaerobic phases of marine immersion corrosion. Corrosion Science, 48(7), 1791-1811.Muntasser, Z., Al-Darbi, M., Tango, M., & Islam, M. R. (2002, January). Prevention of microbiologically influenced corrosion using coatings. In CORROSION 2002. NACE International. Permeh, S., Boan, M. E., Tansel, B., Lau, K., & Duncan, M. (2019, February). Update on Mitigation of MIC of Steel in a Marine Environment with Coatings. In Coatings+, SSPC 2019. Permeh, S., Li, B., Boan, M. E., Tansel, B., Lau, K., & Duncan, M. (2018, July). Microbially Influenced Steel Corrosion with Crevice Conditions in Natural Water. In CORROSION 2018. NACE International.Permeh, S., Reid, C., Echeverría Boan, M., Lau, K., Tansel, B., Duncan, M., & Lasa, I. (2017, April). Microbiological Influenced Corrosion (MIC) In Florida Marine Environment: A Case Study. In CORROSION 2017. NACE International. Figure 1

Characterization of Biofilm Formation and Coating Degradation by Electrochemical Impedance Spectroscopy

Recent findings showed severe localized corrosion of submerged steel bridge piles in a Florida bridge and was associated with microbial activity in the presence of marine foulers. Microbiologically influenced corrosion (MIC) can cause severe degradation of submerged steel infrastructure with the presence of biofilm associated with microorganisms such as sulfate reducing bacteria (SRB). Coatings have been developed to mitigate MIC and marine fouling. Coating degradation and disbondment can occur as a result of microbial attack due to the production of metabolites that degrade coating chemical and physical properties. In the work described here, electrochemical impedance spectroscopy (EIS) was conducted to identify microbial activity and degradation of an antifouling coating exposed to SRB-inoculated modified Postgate B solution. The measurements resulted in complicated impedance with multiple loops in the Nyquist diagram associated with the coating material, development of surface layers (biofilm), and the steel interface. Deconvolution of the impedance results and fitting to equivalent circuit analogs were made to identify coating characteristics and surface layer formation. EIS test results revealed coating degradation and subsequent formation of surface layers associated with SRB due to coating self-polishing and depletion of biocide components.

Test method for degradation of TiZrN coatings on metal substrate using electrical resistance measurement

A test method was devised to evaluate the degradation level of TixZr1-xN (x = 0.1, 0.5) coatings on SUS304 under thermo-mechanical stress. A pulsed laser ablation system was employed to apply repetitive local stress. A system was designed to determine the degradation from the electrical conductivity differences between the TiZrN coating and the substrate. The electrical resistance between the stress loaded area and the stress un-loaded area was measured using a multimeter. The resistance gradually decreased by more than 60% as the number of laser ablations increased. The resistance displayed the convergence value, which was considered the failure point of the coating layer. SEM-EDS and GIXRD analysis of the coating layer showed an increase in the element concentration of substrate components under laser ablation, which indicated that the decrease in resistance was due to the diffusion of the substrate elements.

Assessment of usability of the exploited gas turbine blade heat-resistant coatings

The exploitation process of gas turbines features various damage to their elements with various effects on their usability. The overheating of the blade material, especially of uncooled blades constitutes damage that is very difficult to identify and a failure hazard that is very difficult to classify. The article presents the results of testing of selected factors on the condition and degradation of heat-resistant coatings (insulation and protective layers) of gas turbine blades from jet motors for manoeuvring aircraft drive units. The deliberations were focused on determining the impact of temperature and exhaust fumes on the condition of heat-resistant coatings. The laboratory experiment demonstrated a negative impact of high temperature exceeding the blade's operating range and its duration on the technical condition of the heat-resistant coating. The article's main context regards the assessment of the technical condition of the exploited blade's coatings. The study took into account the chemical and high-temperature impact of the operating factor. The conducted testing allowed determining the changes in the structure and properties of the heat-resistant coatings after long-term impact of exhaust fumes during exploitation. It was demonstrated that the impact of exhaust fumes with a higher temperature than the operating temperature causes the coating's degradation throughout a longer period of time.It has been found that during the exploitation the quality of coatings decreases non-linearly, which results in deterioration of their protective properties, and, consequently, the durability of gas turbine blades.

The degradation mechanisms in ion-plasma nanostructured coatings under the conditions of contact cyclic loads

The paper describes and attempts to explain the stages of initiation and development of fatigue wear of TiAlSi system nanostructured coatings under contact cyclic loads. The thickness of the coatings obtained by vacuum ion-plasma deposition was 8–10 μm. The electron microscopic tests were a powerful tool to analyze both coating structure and destruction processes. The tests, as well as the mechanisms and methods for assessing the process of coating fatigue degradation of coatings can be successfully expanded to a wide variety of materials.

Corrosion resistance and thermal-mechanical properties of ceramic pellets to molten calcium-magnesium-alumina-silicate (CMAS)

Because gas turbine engines must operate under increasingly harsh conditions, the degradation of thermal barrier coatings (TBCs) by calcium-magnesium-alumina-silicate (CMAS) is becoming an urgent issue. Mullite (3Al 2 O 3 ·2SiO 2 ) is considered a potential material for CMAS resistance; however, the performance of mullite in the presence of CMAS is still unclear. In this study, mullite and Al 2 O 3 –SiO 2 were premixed with yttria stabilized zirconia (YSZ) in different proportions, respectively. Porous ceramic pellets were used to conduct CMAS hot corrosion tests, and the penetration of molten CMAS and its mechanism were investigated. The thermal and mechanical properties of the samples were also characterized. It was found that the introduction of mullite and Al 2 O 3 –SiO 2 mitigated the penetration of molten CMAS into the pellets owing to the formation of anorthite, especially at 45 wt% mullite/55 wt% YSZ. Compared with Al 2 O 3 –SiO 2 , mullite possesses a higher chemical activity and undergoes a faster reaction with CMAS, thus forming a sealing layer in a short time. Additionally, the thermal expansion coefficient, thermal conductivity, and fracture toughness of different samples were considered to guide the architectural design. Considering the CMAS corrosion resistance, thermal and mechanical performance of TBCs systematically, a TBC system with a multilayer architecture is proposed to provide a theoretical and practical basis for the design and optimization of the TBC microstructure.

Degradation of ytterbium disilicate environmental barrier coatings in high temperature steam atmosphere

The use of Ceramic Matrix Composites (CMCs) in the hottest part of an aero engine promises great improvements in fuel efficiency by decreasing component weight and allowing higher gas inlet temperatures. However, an environmental barrier coating (EBC) is required to protect the CMC from the corrosive water vapour contained in the combustion environment.Here, CMC specimens were coated with a silicon bond coat and ytterbium disilicate (Yb2Si2O7) layer using air plasma spraying. The specimens were subsequently exposed to a water steam environment at 1350 °C for hundreds of hours. Stress evolution and phase stability were measured throughout to observe possible degradation. Cross-sectioning of the samples revealed the occurrence of sintering, the formation of a thermally grown oxide along the silicon/EBC interface, and a reaction between the ytterbium disilicate and silica. However, no coating failure was observed, even after 750 h of isothermal exposure to the hot steam environment.

Monitoring of abiotic degradation of photocrosslinked silicone acrylate coatings: the fate of the photoinitiator.

Photocrosslinked silicone acrylates are used in a variety of applications, such as printing inks, adhesives, or adhesive release liners. Their production requires the use of a photoinitiator. Even if the photoinitiator represents a minor mass in the photocurable formulation (2-10%), it is used in excess and residual amounts may therefore remain in the polymerized products and possibly migrate into the environment during the use of the products and/or at their end-of-life stage. Little is known on the possible degradation of silicone acrylate which may increase the potential release. The present study investigated the release of Darocur 1173, the most commonly used photoinitiator, from silicone matrix and the effect of accelerated photoageing on the extent of the phenomenon. Leaching tests in water were conducted on thin-coated plastic film (release liners) made of a mixture of polypropylene and polyethylene. Results showed that 44% of the Darocur 1173 photoinitiator initially used in silicone formulation was released from silicone matrix in the leaching test. Accelerated photoageing obtained by UV irradiation of the films for up to 200h was found to favor photoinitiator degradation but also induced a strong and fast oxidation of silicone-coated liners as compared to that of uncoated ones. Graphical abstract.

Biodegradable hyaluronan hydrogel coatings on acellular dermis grafts—A potential strategy to improve biologic graft durability in hernia repair application

Biologic grafts used in hernia repair undergo rapid cellular infiltration and remodeling, but their premature degradation often results in hernia recurrence. We hypothesize that a temporary barrier that prevents infiltration of acute inflammatory cells into the graft during the initial 4 weeks of implantation could mitigate graft degradation. The purpose of this study is to design tyramine-substituted hyaluronan (THA) hydrogel coatings with tunable degradation properties, as a means to develop a resorbable barrier for human acellular dermis grafts (HADM). THA plugs prepared at different cross-linking densities, by varying cross-linking agent concentration (0.0001-0.0075% H2 O2 ), demonstrated varying rates of in vitro degradation (25 U/mL hyaluronidase, 48 h). Based on these results, HADM grafts were coated with THA at three cross-linking densities (0.0001%, 0.00075%, and 0.003% H2 O2 ) and THA coating degradation was evaluated in vitro (25 U/mL hyaluronidase, 48 h) and in vivo (rat intraperitoneal implantation, 1-4 weeks). THA coatings degraded in vitro and in vivo with the lowest cross-linking density (0.0001% H2 O2 ), generally showing greater degradation as evidenced by significant decrease in coating cross-sectional area. However, all three coatings remained partially degraded after 4 weeks of in vivo implantation. Alternate strategies to accelerate in vivo degradation of THA coatings are required to allow investigation of the study hypothesis. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2664-2672, 2019.

The biodegradation of polyester and polyester polyurethane coatings using Papiliotrema laurentii

The rate and severity of polyurethane (PU) coating degradation is due to a combination of both abiotic and biotic factors. The contribution of biotic factors to the degradation process has not been fully realized, in part, because it is assumed that microorganisms cannot survive exclusively on polyurethane-based coatings. We isolated a strain of Papiliotrema laurentii that, as a biofilm, is capable of degrading a polyester-based polyurethane coating. The biodegradation potential of this strain was screened initially with Impranil®-DLN and then against biodegradable polyesters (polyethylene succinate and polyethylene adipate) and a thermoset polyester polyether polyurethane, Irogran®, with no additional carbon sources over 8 days at a relative humidity of >95%. We confirmed that P. laurentii preferentially hydrolyzed both polyesters coatings and the polyester segment of Irogran® coatings using optical and infrared microscopy techniques. The chemical and metabolic differences observed during the degradation of PES coatings compared to PEA and Irogran® coatings indicate that growth was not required for these coatings to be degraded. This strain of P. laurentii can both hydrolyze and metabolize polyester-based coatings under high humidity over 8 days. These microscopic and analytical data revealed how biodegradation was potentially linked to survival using this fungus isolated from the environment.

High temperature oxidation behavior of Inc-738/NiCrAlY/LaMA thermal barrier coating system

The high temperature oxidation behavior of Inc-738/NiCrAlY/LaMgAl11O19 (LaMA) thermal barrier coating system was studied and compared with Inc-738/NiCrAlY/8YSZ coating system. The morphology of coatings, formation of TGO layer and degradation of coatings during oxidation process were investigated. The results indicated that the thermal cycling lifetime of LaMA coating was more than 8YSZ coating. The morphological evaluation of LaMA coating revealed that the recrystallization of amorphous phase was occurred. The 8YSZ ceramic top coat was sintered and microstructure was generated from columnar to equiaxed structure during thermal cycling process. Following the formation of a continuous alumina layer, undesirable oxides created at the TGO/bond coat (BC) interface in the LaMA coating system, whereas, unwanted oxides created at the TGO/top coat (TC) interface in the 8YSZ coating system and also it is believed that the oxidation of coating systems in steady-state stage was occurred under the diffusion-chemical mechanism and chemical mechanism, respectively. Therefore, the different failure mechanisms were observed in both coating systems. In the 8YSZ coating, the cracks nucleated at the TGO/TC interface, while in the LaMA coating, the cracks nucleation were occurred in TGO layer.

Microstructural degradation and interdiffusion behavior of NiAl and Ge-modified NiAl coatings deposited on Alloy 602 CA

Ge-modified and conventional nickel aluminide coatings were deposited on Alloy 602 CA via a single-step slurry manufacturing process and diffusion heat treated at 800 °C for 5 h. The effect of Ge-addition to slurry nickel aluminide coatings was investigated with respect to the microstructural degradation of coatings during isothermal exposure at different temperatures for 100 h. Addition of Ge resulted in the formation of Cr- and Ge-rich precipitates distributed within a β-phase diffusion zone. The inter-diffusion zone (IDZ) consisted of (Ni,Cr)3Ge phase. On the other hand, the employment of pure Al powder led to the formation of Al-rich phases such as ζ and δ near the surface and a strong Al-gradient in the Ge-free β-phase coating. While the extent of microstructural degradation was similar for both coatings after 100 h at 900 °C, exposure at higher temperatures resulted in Kirkendall void formation in the NiAl coating, whereas the initial (Ni,Cr,Fe)3Ge layer transformed into chromium carbides, which in-situ formed a dense interlayer below the aluminide and obstructed interdiffusion in the Ge-containing coating. At 1050 °C, the NiAl coating delaminated due to the severe Kirkendall porosity, which resulted in the oxidation of the interface and nitridation of the alloy and at 1200 °C it led to the complete dissolution of the NiAl coating. The Ge-containing equivalent maintained its integrity and protective behavior in both cases.

A review on protective polymeric coatings for marine applications

The main objective of this review is to discuss the recent research on polymer-based surface coatings contributing to the protection against marine biofouling based on the knowledge available in literature, supplemented by means of figures, mechanism illustrations, mathematical models, and equations. A need for studies on the mathematical behavior of such coatings is emphasized, composed of quantitative evaluation of foul-release performance of coatings using mathematical equations of the concerned parameters. Apart from the synthesis of protective polymeric coatings, understanding the relationship between characteristics of coating materials and accompanying foul-release and antifouling mechanism is important. In this regard, efforts have been made to equally evaluate, simulate, and measure the appropriate performance of the coatings. By examining the physicochemical and mechanical properties of the polymers, adhesion behavior has been found to be one of the prerequisites for the success of polymeric coatings for marine applications. The potential development of a broad spectrum of methods used to evaluate the foul-release performance of polymeric coatings depending on adhesion behavior of fouling organisms with the coatings has been discussed. From the analysis of the factors affecting degradation of coatings, environmental interference is declared a key factor for complete degradation of polymeric coatings. This review opens up new research directions to improve the adhesion performance of polymeric coatings for ship hulls designed with tunable viscoelasticity by the incorporation of elastomeric polymers (like polydimethylsiloxane) into stiff polymers (like epoxy resins) with and without the utilization of additives, modifiers, and nano-fillers. In addition, it provides methods to improve the foul-release performance of such coatings that work on adhesion behavior of biofouling species attached to the coating surface.

Liquid-Repellent Metal Oxide Photocatalysts.

Metal oxide photocatalysts (MOPCs) decompose organic molecules under illumination. However, the application of MOPCs in industry and research is currently limited by their intrinsic hydrophilicity because MOPCs can be wetted by most liquids. To achieve liquid repellency, the surface needs to possess a low surface energy, but most organic molecules with low surface energy are degraded by photocatalytic activity. Herein, current methods to achieve liquid repellency on MOPCs, while preventing degradation of hydrophobic coatings, are reviewed. Classically, composite materials containing MOPCs and hydrophobic organic compounds possess good liquid repellency. However, composites normally form irregular coatings and are hard to prepare on surfaces such as those that are mesoporous or nanostructured. In addition, the adhesion of composites to substrates is often weak, resulting in delamination. Recent studies have shown that the direct grafting reaction of polydimethylsiloxane (PDMS) from silicone oil (methyl-terminated PDMS) under illumination results in a stable polymer brush. This easy and simple grafting method allows us to create stable liquid-repellent surfaces on MOPCs of various types, structures, and sizes. In particular, super-liquid-repellent drops with an underlying air layer can be created on PDMS-grafted nano-/microstructured MOPCs. Potential applications of surfaces combining liquid repellency and photocatalytic activity are also discussed; thus offering new ways of using MOPCs in a wider range of applications.

Field-Programmable Gate Array-Based Coating Impedance Detector for Rapid Evaluation of Early Degradation of Protective Coatings

In this paper, a novel, compact, And field-programmable gate array (FPGA)-based coating impedance detector (CID 2.0) was proposed to rapidly detect the early degradation of coatings. An FPGA-based hardware design with an embedded analog-to-digital converter and digital-to-analog converter was successfully applied to develop CID 2.0. A method for generating high-quality signals for FPGA by using the delta-sigma modulation was used. This method provided higher measurement ranges and accuracies for detecting coating impedance values. The performance of CID 2.0 was compared with that of a conventional potentiostat. For comparison, the impedance value of ideal resistors and commercial coatings was measured using the proposed and conventional methods. The results indicated an optimal correlation between the impedance values measured using CID 2.0 and that measured using conventional potentiostat in the range of 10 6 - 10 10 Ω-cm 2 . Furthermore, when the continuous monitoring experiments were conducted, CID 2.0 exhibited high sensitivity to detect impedance changes associated with the coating delamination process. The preliminary results suggested that CID 2.0 can be used to observe the changes in the coating impedance values in the critical range to enable workers to determine whether coating maintenance should be scheduled.

Effect of Bacillus flexus on the Degradation of Epoxy Resin Varnish Coating in Seawater

Effect of Bacillus flexus on the Degradation of Epoxy Resin Varnish Coating in Seawater

Degradation of boron nitride interfacial coatings fabricated by chemical vapor infiltration on SiC fibers under ambient air/room temperature conditions

Hexagonal boron nitride (h-BN) interfacial coatings were deposited on SiC fibers by chemical vapor infiltration (CVI) and their degradation behavior under ambient air/room temperature conditions was studied with time. Degradation of the interfacial coatings with time was investigated by characterizing the morphology and microstructure of these materials with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). Thermogravimetry coupled with differential thermal analysis (TG-DTA) and X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical reactions and phase transitions taking place in the BN coatings. The results showed that the as-deposited BN interfacial coatings fabricated by CVI were compact and well bonded to the SiC fibers. BN coatings remained relatively stable under ambient air/room temperature conditions for 50 h, while severe degradation was observed after 500 h of exposure. The degradation of BN interfacial coatings was mainly caused by two factors, namely, reaction with atmospheric air to produce boric oxide and amorphization of the hexagonal structure. The degradation observed under ambient air/room temperature might be due to incomplete crystallinity of BN interfacial coatings. Presence of water vapor may accelerate degradation of the coatings. The results of this degradation test can be used as a reference for the storage of BN coatings fabricated by CVI.

Fluorescence study of the hydrolytic degradation process of the polysiloxane coatings of basalt fibers

Basalt fiber surfaces were modified using different silane aqueous solutions to generate a variety of polyorganosiloxane coatings. After removing the commercial coating of the fibers by calcination and subsequent activation processes, polysiloxanes were grafted on the fiber surfaces. Three aqueous solutions were used for the silanization: (i) γ-aminopropyltriethoxysilane, APTES; (ii) γ-aminopropylmethyldiethoxysilane, APDES, and (iii) a mixture of 50% by weight of both APTES + APDES. The silanized fibers were chemically labeled with fluorescein isothiocyanate to be immersed afterwards in different aqueous solutions (pH = 7) to study the hydrolytic degradation of the polysiloxane coatings. The hydrolysis phenomena were monitored by steady state fluorescence at different temperatures to subsequently study the kinetics of the process. The hydrolysis process was also studied by monitoring the pH of the solution in which the silanized fibers were immersed as a function of time. The data obtained from fluorimetry were fitted to an integrated expression arising from a first order kinetic process, which allowed estimation of the activation energies of the hydrolytic degradations. The results indicated that although the hydrolytic rate of the polysiloxane coatings increased in the order APDES < APDES + APTES < APTES, differences in the mechanism were not the cause of that order; the initial concentration of siloxane bonds able to be hydrolyzed was responsible.

Diffusion cell investigations into the acidic degradation of organic coatings

Diffusion cell investigations into the acidic degradation of organic coatings

Experimental Studies on Corrosion Behavior of Ceramic Surface Coating using Different Deposition Techniques on 6082-T6 Aluminum Alloy

Aluminum alloys cannot be used in aggressive corrosion environments application. In this paper, three different surface coating technologies were used to coat the 6082-T6 aluminum alloy to increase the corrosion resistance, namely Plasma Electrolytic Oxidation (PEO), Plasma Spray Ceramic (PSC) and Hard Anodizing (HA). The cross-sectional microstructure analysis revealed that HA coating was less uniform compared to other coatings. PEO coating was well adhered to the substrate despite the thinnest layer among all three coatings, while the PSC coating has an additional loose layer between the coat and the substrate. X-ray diffraction (XRD) analysis revealed crystalline alumina phases in PEO and PSC coatings while no phase was detected in HA other than an aluminum element. A series of electrochemistry experiments were used to evaluate the corrosion performances of these three types of coatings. Generally, all three-coated aluminum showed better corrosion performances. PEO coating has no charge transfer under all Inductive Coupled Plasma (ICP) tests, while small amounts of Al3+ were released for both HA and PSC coatings at 80 °C. The PEO coating showed the lowest corrosion current density followed by HA and then PSC coatings. The impedance resistance decreased as the immersion time increased, which indicated that this is due to the degradation and deterioration of the protective coatings. The results indicate that the PEO coating can offer the most effective protection to the aluminum substrate as it has the highest enhancement factor under electrochemistry tests compared to the other two coatings.