scholarly journals Effect of Microstructure on the Localized Corrosion and Stress Corrosion Behaviours of Plasma-Electrolytic-Oxidation-Treated AA7075 Aluminum Alloy Forging in 3.5 wt. %NaCl Solution

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
A. Venugopal ◽  
Rajiv Panda ◽  
Sushant Manwatkar ◽  
K. Sreekumar ◽  
L. Ramakrishna ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Plasma Electrolytic Oxidation ◽  
Tensile Tests ◽  
Localized Corrosion ◽  
Nacl Solution ◽  
Uncoated Sample ◽  
Electrolytic Oxidation ◽  
Metallographic Observation ◽  
The One ◽  
Plasma Electrolytic

The influence of metallurgical heterogeneities such as coring and intermetallic phases on the corrosion and stress corrosion cracking behaviours of AA7075 aluminium alloy forging was examined in 3.5 wt. % NaCl solution with and without plasma electrolytic oxidation coating. Electrochemical test results demonstrated significant improvement in the corrosion resistance of the alloy after PEO coating. Stress corrosion results show that the metallurgical heterogeneities resulted in a loss in elongation of the uncoated sample in NaCl (11.5%) when compared to the one tested in air (12.9%). The loss in elongation of the uncoated sample was shown to be due to localized corrosion-assisted mechanical cracking rather than true stress corrosion based on preexposure tensile tests followed by posttest metallographic observation of the stress corrosion tested samples. This was further confirmed by the fractographic examination of the failed samples, which exhibited a typical ductile cracking morphology for all the coated and uncoated specimens.

Corrosion Characteristics of PEO Films on AZ31 Magnesium Alloys

2011 ◽  
Vol 189-193 ◽  
pp. 256-259
Author(s):  
Li Wang ◽  
Li Chen ◽  
Wen Fu
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Plasma Electrolytic Oxidation ◽  
Silicate Solution ◽  
Az31 Magnesium Alloy ◽  
Nacl Solution ◽  
Pitting Corrosion Resistance ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Az31 Magnesium Alloys

The aim of this work is to discuss the corrosion characteristics of plasma electrolytic oxidation (PEO) films formed on AZ31 magnesium alloys in alkaline silicate solution. The uniform and pitting corrosion resistance of the PEO films was investigated by potentiodynamic polarization tests and potentiodynamic scanning curve tests. The composition, the structure and the element contents of the films after immersed in 3.5 wt.% NaCl solution for different time were investigated by XRD、SEM and EDS. The results indicated that the corrosion occurred on AZ31 magnesium alloy and treated PEO samples during five days immersion, but the corrosion tendency of the PEO treated samples is smaller than that of AZ31 magnesium alloy.

Corrosion Mechanism of PEO Films on AZ31 Magnesium Alloys

2012 ◽  
Vol 461 ◽  
pp. 220-223 ◽  
Author(s):  
Li Wang ◽  
Wen Fu ◽  
Li Chen
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Plasma Electrolytic Oxidation ◽  
Silicate Solution ◽  
Corrosion Mechanism ◽  
Nacl Solution ◽  
Electrolytic Oxidation ◽  
Corrosion Mechanisms ◽  
Plasma Electrolytic ◽  
Az31 Magnesium Alloys

The corrosion mechanisms of plasma electrolytic oxidation (PEO) films formed on AZ31 magnesium alloys were discussed in alkaline silicate solution. The structure and element contents of the films after immersed in 3.5 wt.% NaCl solution were investigated by SEM and EDS. The results indicated that the corrosion occurred on AZ31 magnesium alloy and the treated PEO samples during five days immersion. The corrosion procedure of the samples was depicted.

Microstructure and Corrosion Resistance of Al2O3-ZrO2 Composite Coating on Biomedical Magnesium Alloy Fabricated by Cathodic Plasma Electrolytic Oxidation

2012 ◽  
Vol 184-185 ◽  
pp. 1068-1071 ◽  
Author(s):  
Yun Long Wang ◽  
Miao Wang ◽  
Zhao Hua Jiang
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Composite Coating ◽  
Bonding Strength ◽  
Plasma Electrolytic Oxidation ◽  
Corrosion Current ◽  
Uncoated Sample ◽  
Electrolytic Oxidation ◽  
Cathodic Plasma ◽  
Plasma Electrolytic

A relatively new method called cathodic plasma electrolytic oxidation (CPEO) was development to fabricate Al2O3–ZrO2 composite coating on AZ91 biomedical magnesium alloy. The microstructure and properties of the composite coating including phase composition, surface and cross section morphology, thickness and bonding strength were investigated. The corrosion behavior of the coated magnesium alloy in simulated body fluids(SBF) was primarily evaluated. The results showed that the coating was composed of c-ZrO2, α-Al2O3 and γ-Al2O3. The coating surface was coarse and porous with the average pores diameters of 5 µm. The thickness of the coating was about 60 µm and the bonding strength of coating to the AZ91 substrate was 22 MPa. The polarization test indicated that corrosion potential (Ecorr) and corrosion current density (icorr) of the coated samples in SBF were −1.56V and 8.89×10-7 A/cm2 , respectively, whose corrosion resistance was significantly improved compared to the uncoated sample.

scholarly journals Fabrication of a Protective Hybrid Coating Composed of TiO2, MoO2, and SiO2 by Plasma Electrolytic Oxidation of Titanium

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1182
Author(s):  
Tehseen Zehra ◽  
Mosab Kaseem ◽  
Shakhawat Hossain ◽  
Young-Gun Ko
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Pure Titanium ◽  
Titanium Substrate ◽  
Sio2 Nanoparticles ◽  
Hybrid Coating ◽  
Structural Defects ◽  
Nacl Solution ◽  
Microstructural Observation ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic

This work examined the influence of dual incorporation of MoO2 and SiO2 on the corrosion behavior of pure titanium treated via plasma electrolytic oxidation (PEO). To achieve this purpose, pure titanium substrate was treated via PEO in an alkaline-molybdate electrolyte without and with SiO2 nanoparticles. The microstructural observation revealed that the addition of SiO2 nanoparticles into the electrolyte during PEO helped to seal the structural defects in the PEO coating so that a rougher, thicker, and denser coating rich in SiO2 was successfully obtained. From the electrochemical measurements in a 3.5 wt.% NaCl solution, the TiO2-MoO2-SiO2 hybrid coating exhibited a higher corrosion resistance than the TiO2-MoO2 coating which was attributed to the sealing effect by stable SiO2 nanoparticles.

Fabrication of Al2O3 Ceramic Coating on AZ91 Biomedical Magnesium Alloy and the Corrosion Resistance in SBF

2013 ◽  
Vol 365-366 ◽  
pp. 1114-1117
Author(s):  
Yun Long Wang ◽  
Shuo Wang ◽  
Miao Wang ◽  
Li Jie Shi ◽  
Hui Rong Guo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Plasma Electrolytic Oxidation ◽  
Ceramic Coating ◽  
Coated Sample ◽  
Uncoated Sample ◽  
Electrolytic Oxidation ◽  
Simulated Body Fluids ◽  
Plasma Electrolytic

Al2O3ceramic coating was fabricated on AZ91 biomedical magnesium alloy by plasma electrolytic oxidation. The microstructure of the coatings was characterized. The corrosion behavior of the coated magnesium alloy in simulated body fluids (SBF) was evaluated. The results showed that the as prepared coating was composed of crystal Al2O3, including much α-Al2O3and some γ-Al2O3. The Al2O3.coating showed porous surface and the biggest diameters of the holes were about 6-7 um, and the smallest were about 1 um. The corrosion tests in SBF indicated that corrosion resistance of Al2O3coated sample was significantly improved compared to the uncoated sample.

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