Abstract:The ceramic surface treatment of aluminum alloy is an important means to improve the mechanical properties and corrosion resistance of aluminum alloy.This paper focuses on the process and research status of aluminum alloy anodic oxidation technology and aluminum alloy micro-arc oxidation technology and analyzes the future development direction.
“…Among them, 402.61 eV matches the EV value of Sc 3+ in Sc 2 O 3 , indicating that Sc 3+ eventually became Sc 2 O 3 during the MAO process. The possible reactions in the whole MAO process are listed [21,22]: Figure 3 (a) XRD results of the coating and (b) XPS results of Sc.…”
Micro-arc oxidation (MAO) coatings were fabricated on 2195 aluminium-lithium alloy substrate, using a silicate and phosphate electrolyte with variable scandium nitrate (Sc(NO 3 ) 3 ) concentrations. The properties of the coatings were analysed by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical workstation. The comprehensive analysis demonstrates that adding proper amount of Sc(NO 3 ) 3 increased the oxidation voltage, which transformed the worm shape discharge micropores into round-hole shape, and the MAO coatings presented a doublelayer structure. The primary phase composition of the coatings was γ-Al 2 O 3 , α-Al 2 O 3 , Sc 2 O 3 and Al 3 Sc. The optimum concentration of Sc(NO 3 ) 3 was 0.6 g L −1 . The hardness reached a maximum value of (1284 ± 43.5) HV, which was about 2.5 times higher than that without adding. The self-corrosion current density reduced from 138.00 × 10 −7 A cm −2 (substrate) to 3.65 × 10 −7 A cm −2 , which was approximately two orders of magnitude lower, indicating that the corrosion resistance was improved.
“…Among them, 402.61 eV matches the EV value of Sc 3+ in Sc 2 O 3 , indicating that Sc 3+ eventually became Sc 2 O 3 during the MAO process. The possible reactions in the whole MAO process are listed [21,22]: Figure 3 (a) XRD results of the coating and (b) XPS results of Sc.…”
Micro-arc oxidation (MAO) coatings were fabricated on 2195 aluminium-lithium alloy substrate, using a silicate and phosphate electrolyte with variable scandium nitrate (Sc(NO 3 ) 3 ) concentrations. The properties of the coatings were analysed by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical workstation. The comprehensive analysis demonstrates that adding proper amount of Sc(NO 3 ) 3 increased the oxidation voltage, which transformed the worm shape discharge micropores into round-hole shape, and the MAO coatings presented a doublelayer structure. The primary phase composition of the coatings was γ-Al 2 O 3 , α-Al 2 O 3 , Sc 2 O 3 and Al 3 Sc. The optimum concentration of Sc(NO 3 ) 3 was 0.6 g L −1 . The hardness reached a maximum value of (1284 ± 43.5) HV, which was about 2.5 times higher than that without adding. The self-corrosion current density reduced from 138.00 × 10 −7 A cm −2 (substrate) to 3.65 × 10 −7 A cm −2 , which was approximately two orders of magnitude lower, indicating that the corrosion resistance was improved.
The Plasma Electrolytic Method of Oxidation (PEMO ) is proved powerful for producing the wear and corrosion-resistant coating of the oxide layer for exclusive applications. This technique is having a better capability for industrial use for growing proactive coatings on material like Aluminium, Magnesium, Titanium for diverse application of lightweight and high temperature requirements applications. The paper consists of review of papers primarily based on the surface modification amendment method of plasma arc oxidation of aluminium and its alloy. Because the process characterized by the discharge generated by electrode, electrolyte composition and oxide coating morphology which might be crucial component for effectiveness of the technique. The purpose of the paper is to write the systematic review for electrodes, electrolyte compositions, and its effect in improving the characteristics of aluminium alloys. There is a large scope for enhancing the method and monitoring the electric parameters of PEMO for massive applications in regions of automotive wherein the modification in surfaces can replace the components by the lightweight aluminium alloy material. The attempt is made to pick the key elements inside the technique. The scope of designing numerous optimization algorithms and analytical modelling is a key area for further research which can help to screen the technique extra precisely to get an optimized coating microstructure.
Through a three-factor, two-level orthogonal experiment, the effects of varying electrical parameters (voltage, frequency, and duty cycle) on the thickness, pressure resistance, corrosion resistance, morphology, and phase composition of the micro-arc oxidized film of aluminum foil in constant voltage mode were investigated. The aluminum foil was oxidized by micro-arc oxidation for 50 min. Eddy-current thickness gauges were used to measure the oxide film’s thickness, TV characterization testers were used to test the film’s resistance to pressure, kinetic potential polarization curves were used to examine the oxide film’s resistance to electrochemical corrosion, and SEM and XRD composition were used to examine the microstructures and phase compositions of the oxide films that were produced. The oxide film’s thickness was increased from 7 μm to 22 μm and the voltage was increased from 350 V to 450 V. The oxide film’s ramp-up time at a frequency and duty cycle of 2000 Hz and 15% could reach 3 s, and the resistance value could reach 98% of the micro-arc oxidation voltage. The oxide film’s icorr decreased by an order of magnitude at high voltage compared to low voltage and the Rp value increased by an order of magnitude, which improved the corrosion resistance. The oxide film’s thickness increased as the voltage increased. Meanwhile, SEM was used to enhance the corrosion resistance. The oxide film thickens as the voltage increases. At the same voltage, the oxide film with a high frequency and low duty cycle has the best voltage resistance. The oxide film generated under high-voltage conditions has regular and dense surface holes, the oxide film’s α-Al2O3 phase increases, and the corrosion resistance in the NaCl medium is enhanced.
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