Microstructure and Properties of MAO Coatings for AZ91D Magnesium Alloy in Varies Work Mode

Cui, Xuejun; Lin, Xiu; Liu, Chun Hai; Yang, Rui; Li, Ming Tian

doi:10.4028/www.scientific.net/msf.747-748.178

Cited by 6 publications

(5 citation statements)

References 10 publications

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“…The electrical parameters of the MAO technique affect the hardness and corrosion protection behavior of coated AZ91D alloy. [90] 2.1.3. Biodegradable and Self-Healing Coatings Composite coatings are successfully applied in automotive, aerospace, marine, electrical, and electronic applications.…”

Section: Composite Coatingsmentioning

confidence: 99%

“…MAO technique is one of the most common and popular techniques to coat AZ91D alloy. [45,51,90,138,139] The deposition time of 15 min, 20% duty cycle, 600 Hz frequency, 2 A working current, and 22 AE 2 °C electrolyte temperature are the important optimum parameters reported for AZ91D coating. [116,118,138] In the MAO coating of Mg-alloys, high voltage ranging from 200 to 500 V was used in various studies.…”

Section: Micro-arc Oxidationmentioning

confidence: 99%

“…The electrical parameters of the MAO technique affect the hardness and corrosion protection behavior of coated AZ91D alloy. [ 90 ]…”

Section: Coating Materials and Techniques: Overall Developments (2012...mentioning

confidence: 99%

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An Impact of the Recent Developments in Coating Materials and Techniques on the Corrosion Response of AZ91D Alloy: A Review

et al. 2023

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AZ91D, a die‐casted alloy, offers several benefits (better saltwater corrosion resistance, suitable castability, and good atmospheric stability) over other grades of magnesium alloy. However, it cannot overcome the challenging requirements of advanced applications in its current form. Extensive research in coating technologies is crucial in enhancing the performance of AZ91D alloy in highly corrosive environments (coastal and marine, industrial, farm, etc.). The high corrosion resistance of AZ91D for various applications is achievable through the deposition of different materials. Developments in coating materials and techniques, with their influence on the corrosion protection behavior of AZ91D alloy, over the last decade (2012–2022), are focused on in this study. It is observed that composite, biodegradable, and self‐healing coatings are gaining popularity. The transition in the coating technology, from conventional to self‐healing coating materials and from conventional to environment‐friendly coating techniques, is a vital part of this discussion. This review further explores how different additives, pre‐treatments, post‐treatments, and corrosion inhibitors affect the corrosion performance of coatings. This study helps select the optimum coating material for AZ91D magnesium alloy to fulfil a specific application requirement and guides toward technological developments in this segment.

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Section: Composite Coatingsmentioning

confidence: 99%

Section: Micro-arc Oxidationmentioning

confidence: 99%

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An Impact of the Recent Developments in Coating Materials and Techniques on the Corrosion Response of AZ91D Alloy: A Review

et al. 2023

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“…A time-saving energy parameter is power density. The positive power density governs the coating's thickness, corrosion and microstructure [70]. The substrate's composition impacts the MAO coating's thickness as well as the growth rates of the coating [71].…”

Section: Electrolyte and Additives For Mao Processmentioning

confidence: 99%

Recent Advances on Biocompatible coating on Magnesium alloys by Micro Arc Oxidation Technique

Pesode

Mane

Dayane

et al. 2023

KEM

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Magnesium alloys are suitable biological material because of its favourable mechanical qualities, high biocompatibility, and biodegradability. However, it has poor corrosion resistance and has rapid dissolution in the corrosive environment which will weakens its mechanical characteristics. The surface characteristics of magnesium alloy must thus be changed using a suitable surface modification technology, such as micro arc oxidation (MAO). This article examines recent developments and advancements in biodegradable surface coatings applied to magnesium alloys. It was observed there are four steps of MAO process, the formation of a thinner and denser barrier, commencement of oxides in bare Ca-Mg matrix following the presence of sparks; the horizontal expansion of the oxide layer, and finally thickening of MAO coating. It was observed that characteristics of MAO coating can changed by varying electrical parameters like duty cycle, current density, type of power output, frequency, and processing time. It was noticed that when all other factors are held constant, duty cycle, processing time, and frequency primarily effect the coating's porosity, number of cracks and thickness, which in turn influences how well the coating performs. DC, AC, pulsed bipolar, and pulsed unipolar, are the four categories into which the current regimes are classified. It was found that, unipolar current mode MAO coatings found to be rough, highly porous, and vulnerable to microcracks due to stronger spark discharge. MAO coating produced in a bipolar current type of mode have larger pores but are more uniform in thickness and compact. It was noticed that the in-vitro cell assays showed cells L929 on the Ca-P coated Mg alloy to have considerably good adhesion, a high growth rate, and strong proliferation (p 0.05). In other words, the cytocompatibility was greatly enhanced by the Ca-P coating. It was discovered that the Ca-P coated Mg alloy improved cell responsiveness and encouraged early bone formation at the implant/bone interface by both conventional pathological examination and immunohistochemistry investigation. The Ca-P coating was found to be an effective method for raising the surface bioactivity of Mg alloy. It was also observed that the calcium phosphate coating deposited by MAO process improve surface biomineralization which is the main mechanism behind bioactivity. Functional groups that are present on surface engage electrostatically through calcium and phosphate ions from solutions to start the biomineralization process. Calcium phosphates have excellent biocompatibility and are quite comparable to the mineral makeup of bone. The current study aims to investigate the bioactivity of calcium phosphate coatings and the characteristics of magnesium and its alloys.

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“…Power density is a time-saving energy parameter. The positive power density plays a determinable role in the thickness, microstructure, and corrosion of the coatings [42]. The composition of the substrate influences the growth rates of the coating [9,43], and affects the thickness of the MAO coating.…”

Section: Electrolyte and Additivesmentioning

confidence: 99%

Research status of magnesium alloys by micro-arc oxidation: a review

Dou

Chen

et al. 2017

Surface Engineering

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Magnesium and its alloys are fascinating candidates for biodegradable implants due to their suitable mechanical properties, biodegradability and biocompatibility. However, the rapid corrosion rate, generation of a large amount of hydrogen gas and increase in local pH of the body fluid limit their potential biomedical applications. Various techniques, including alloying, mechanical processing and surface treatment, have been used to reduce the corrosion rate of materials. Surface treatment is one of the widely used techniques to improve the corrosion resistance of the Mg alloys. Compared to other surface modification processes, micro-arc oxidation can provide good adherent, hard, scratch-resistant, wearresistant, and corrosion-resistant coatings on magnesium alloys. This article mainly reviews the influence of key relatively process parameters, such as electrolytic composition and presence of additives. Normally, electrolytic system and additives can improve the corrosion behaviour of magnesium alloys using appropriate concentration. The future prospects are summarised as well.

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Microstructure and Properties of MAO Coatings for AZ91D Magnesium Alloy in Varies Work Mode

Cited by 6 publications

References 10 publications

An Impact of the Recent Developments in Coating Materials and Techniques on the Corrosion Response of AZ91D Alloy: A Review

An Impact of the Recent Developments in Coating Materials and Techniques on the Corrosion Response of AZ91D Alloy: A Review

Recent Advances on Biocompatible coating on Magnesium alloys by Micro Arc Oxidation Technique

Research status of magnesium alloys by micro-arc oxidation: a review

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