Corrosion and Wear Behavior of PEO Coatings on D16T Aluminum Alloy with Different Concentrations of Graphene

Abstract

The effect of added graphene concentration on the microstructure, phase composition, corrosion-and wear-resistance of plasma electrolyte oxidation (PEO) coatings formed on D16T aluminum alloy in silicate electrolyte with different concentrations of graphene were investigated. The results show that the morphologies of the coatings with graphene were obviously different ascribed to the mode of graphene incorporated into the coating. The coatings consisted of mainly α-Al 2 O 3 , γ-Al 2 O 3 , and Al, which were divided into an outer porous layer and a dense inner layer. The thickness of the coatings increased non-linearly with graphene concentration. The corrosion resistance of the coatings with graphene was significantly improved. The wear resistance of the coatings was also greatly improved apart from the coating with 3 g/L graphene. The coating produced in the electrolyte with 2 g/L graphene exhibited the optimal comprehensive properties because graphene successfully incorporated into the coating via the pores and spread on the surface of the coating.Coatings 2020, 10, 249 2 of 20 are influenced by various process parameters such as the constituent and concentration of electrolytes, oxidation time, substrate, various electrical parameters, and additives [7,8]. The constituent and concentration of the additive play an important role in changing the structure, morphology, wear-and corrosion-resistance of the coatings among those factors. A large number of works about the PEO coatings incorporated particles or powders like TiO 2 [9], ZrO 2 [10], Fe micrograins [11], α-Al 2 O 3 [8], and so on were performed. Zhao et al. [7] studied the effect of graphene oxide on the corrosion resistance of the PEO coating on AZ31 magnesium alloy, and reported that the incorporated graphene oxide markedly decreased micropores and improved the corrosion resistance of AZ31 magnesium alloy. Sarbishei et al. [12] reported that alumina nanoparticles incorporated into the PEO coatings formed on a titanium substrate, reducing the density of the coating and the pores' size. The corrosion resistance was improved with the increase of the alumina concentration, and the coatings formed in the electrolyte with 10 g/L alumina nanoparticles showed the best properties. Fatimah [13] studied the structure and corrosion properties of the coatings formed on 6061 Al alloy through the dual incorporation of SiO 2 and ZrO 2 nanoparticles into the oxide layer and found the coatings with SiO 2 and ZrO 2 displaying the best corrosion resistance because they were used as micropores blocker and cracks filler. Yazdanl et al. [14] studied the tribological performance of graphene/carbon nanotube hybrid reinforced Al 2 O 3 , and it was determined that the coating with graphene nanoplatelets hybrid reinforced Al 2 O 3 composites displayed the best wear resistance. Hvizdos et al. [15] studied the tribological properties of Si 3 N 4 -graphene nanocomposites, and Si 3 N 4 -graphene nanocomposites owned better wear resistance was also confirmed. Belmonte et al. [16] pro...

Surface Modification of Additively Fabricated Titanium-Based Implants by Means of Bioactive Micro-Arc Oxidation Coatings for Bone Replacement

“…Such a porous structure is common for MAO coatings, which is due to micro-discharges occurring during the MAO process [27]. Although the pores can negatively affect the anti-corrosion and wear-resistant properties of the coatings, such a porous structure has a positive effect on the attachment of cells to the surface for biomedical applications [55][56][57]. In the present case, the arithmetic average of the roughness profile (R a ) and the maximum roughness (R z ) of MAO 1 and MAO 3 coatings have approximately the same values (Figure 3B and SI Table S1).…”

Effect of graphene on the microstructure and corrosion resistance of PEO coating formed on D16T aluminum alloy

“…D16T aluminum alloy samples were treated by a pulsed DC power supply (t on :t off = .4 ms:3.6 ms) under a constant voltage regime (500 V) for 10 min. Based on the previous research, 28,29 the base electrolyte and the addition concentration of graphene have been optimized. Meanwhile, the good performance of the aluminum alloy PEO coating can be obtained when 2-g/L graphene was added into the electrolyte.…”

Anodization Time Effect on Silver Particles Deposition on Anodic Oxide Coating over Al Produced by Plasma Electrolytic Oxidation

“…Regarding the Aluminum PEO, reports in the literature have described the incorporation of particles into the oxide coating from the electrolyte to enhance their corrosion resistance, wear, and tribological properties [12][13][14][15], catalytic activity [16][17][18], magnetic properties [19,20], and antimicrobial properties [21][22][23][24][25][26]. Studies that focus on improving the corrosion resistance and tribological properties reported the use of carbon-based additives [12,13] and α-Al 2 O 3 [14], and ZrO 2 [15] powders in the electrolyte. In addition, W, Co, and Ni species are reported as an additive in PEO electrolytes to improve the catalytic properties of alumina coatings in thiophene oxidation [16] and CO conversion to CO 2 [17,18].…”