Effect of ultrasonic on microstructure and growth characteristics of micro-arc oxidation ceramic coatings on 6061 aluminum alloy

The influence of phase gradient within the micro arc oxidation (MAO) coatings on mechanical and tribological behaviors

“…[11] Nevertheless, the hardest zone in the coating is typically located near the substrate-coating interface due to the presence of higher proportion of -Al 2 O 3 phase. [12] The maximum hardness (peak hardness) values with in the MAO coating correspond to [17][18][19][20][21][22] GPa for coatings based on -Al 2 O 3 , 10-15 GPa for -Al 2 O 3 based coatings and 4-9 GPa for coatings based on mullite. [5] It was although less reported but widely believed that the proportion of -Al 2 O 3 is highest towards the substratecoating interface while -Al 2 O 3 phase predominantly presents at the coating surface.…”

“…[13][14] Accordingly, the typical hardness distribution in the MAO coatings with a peak hardness near the substrate-coating interface followed by gradual decrease in hardness towards the coating surface has been reported by a large number of researchers. [12,[15][16][17][18][19][20][21][22][23] Therefore, the tribological performance as evaluated under diverse wear modes such as abrasion, erosion and sliding demonstrate the exceptional performance of MAO coatings deposited on widely different Al alloys. [24] A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 3 Despite the above understanding, several subsequent research works have only reported a single hardness value for the MAO coating, [7][8][25][26] while in some cases, more meaningfully, it was explicitly mentioned that the hardness value measured corresponds to the internal dense layer alone.…”

Fabrication and characterization of hydrophobic microarc oxidation/poly-lactic acid duplex coating on biodegradable Mg–Ca alloy for corrosion protection

“…Microarc oxidation (MAO) is a chemical conversion process and is one of the most appropriate method for Mg alloys owing to its excellent abrasive resistance, enhanced corrosion resistance and high bonding strength to the substrate [3,[5][6][7]. However, MAO coating is not able to provide long term corrosion protection for Mg alloys in physiological environment owing to its porous structure [5,8].…”

Binary Additives Enhance Micro Arc Oxidation Coating on 6061Al Alloy with Improved Anti-Corrosion Property

“…Therefore, increasing the thickness and reducing the porosity of MAO coatings are two effective methods of enhancing the anti-corrosion properties of these coatings. Many factors can affect the thickness and porosity of MAO coatings, such as elements in the metal substrate [16,17], compositions of the electrolyte [18][19][20], processing time [21,22], processing temperature [23], current density [24][25][26], the type of power source [27][28][29], and other process assistance methods [30][31][32].…”