Improving Corrosion Resistance of AA2014 Welds with Micro Arc Oxidation

2013 ◽  
Vol 765 ◽  
pp. 634-638 ◽  
Author(s):  
Roshan Jacob ◽  
S.A. Srinivasan ◽  
K. Sivaprasad ◽  
V. Muthupandi
Keyword(s):  
Corrosion Resistance ◽  
Current Mode ◽  
Silicate Solution ◽  
The Other ◽  
X Ray Diffraction ◽  
Gas Tungsten Arc ◽  
Weld Metals ◽  
Full Penetration ◽  
Gtaw Process ◽  
Micro Arc Oxidation

Autogenous single pass full penetration welds of 2.8 mm thick AA 2014 plates were produced by un-pulsed and pulsed gas tungsten arc welding (GTAW) process. In pulsed current mode, two levels of pulsing viz., 3 and 6 Hz were employed. In order to improve the corrosion resistance of weld metals, micro arc oxidation (MAO) treatment was given in aqueous silicate solution containing either borax or tungstate. The MAO treatment was carried out for 10, 20 and 30 minutes. Irrespective of the electrolyte composition, surface roughness increased with increasing treatment duration. However, the effect was observed to be significant with borax addition. X-ray diffraction studies showed that γ-Al2O3 content in the coating continued to increase up to 20 minutes and for the coating produced with 30 minutes duration the α-Al2O3 content was found to be more than γ-Al2O3. The coating treated for 30 minutes exhibited relatively poorer corrosion resistance than the other coated specimens. The better corrosion resistance offered by the coating obtained after 20 minutes, compared with the other coatings, could be attributed to the nature of the oxide and its content. Even though tungstate addition improved hardness of the coating, borax addition was found to enhance the corrosion resistance.

Study On the Corrosion Resistance Properties of the Ceramic Coating Obtained Through Microarc Oxidation on the Aluminium Alloy Surface

2007 ◽  
Vol 353-358 ◽  
pp. 1733-1736 ◽  
Author(s):  
Fei Chen ◽  
Hai Zhou ◽  
Chen Chen ◽  
Fan Xiu Lu ◽  
Fan Xiu Lu
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Ceramic Coating ◽  
Microarc Oxidation ◽  
Electrochemical Corrosion ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
Micro Arc Oxidation ◽  
Coating Formation ◽  
Α Al2o3

Oxidation ceramic coating was directly synthesized on LY12 aluminium alloy by micro-arc oxidation (MAO) process in Na2SiO3 electrolyte solution with the Na2WO4-KOH-Na2EDTA addition. The corrosion resistance of the coating was tested using CS300P electrochemical corrosion workshop in 3.5% NaCl solution. Using the scanning electron microscopy (SEM) and X-ray diffraction (XRD), the cross-section microstructure, the surface morphology and the phase structure of the micro-arc oxidation ceramic coating were analyzed. The results showed that the corrosion resistance of the micro-arc oxidation ceramic coating in 3.5% NaCl solution was enhanced remarkably, the corrosion velocity was obviously slowed down. The thickness of micro-arc oxidation ceramic coating was about 11μm. The final phases in the coating were found to be α-Al2O3 and γ-Al2O3. The mechanism of the oxidation ceramic coating formation was investigated too.

scholarly journals Thermal and Residual Stress Distributions in Inconel 625 Butt-Welded Plates: Simulation and Experimental Validation

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Harinadh Vemanaboina ◽  
Edison Gundabattini ◽  
Kaushik Kumar ◽  
Paolo Ferro ◽  
B Sridhar Babu
Keyword(s):  
Residual Stress ◽  
Arc Welding ◽  
Thermomechanical Analysis ◽  
Numerical Code ◽  
Inconel 625 ◽  
Stress Distributions ◽  
X Ray Diffraction ◽  
Gas Tungsten Arc ◽  
Thermal Measurements ◽  
Gtaw Process

Thermal and residual stress distributions induced by the gas tungsten arc welding (GTAW) process on Inconel 625 were studied using numerical simulation and experiments. A multi-pass welding model was developed that uses a volumetric heat source. Thermomechanical analysis is carried out to assess the Thermal and residual stress distributions. Experiments were carried out with 5 mm thick Inconel 625 plates. X-ray diffraction techniques were used to measure residual stresses, and IR thermometry was employed to capture the temperature values on the welded joints. Simulations were performed with ANSYS numerical code, and a close agreement was found between the predicted and experimentally measured residual stress. Thermal measurements were collected pass by pass from the analysis, and the agreement was 9.08%. The agreement between the measured and analysed residual stress was 11%.

Effects of graphene on the microstructure and properties of MAO coatings formed on AA7050

2020 ◽  
Vol 111 (6) ◽  
pp. 463-468
Author(s):  
Bo Xu ◽  
Yafeng He ◽  
Xiangzhi Wang ◽  
Weimin Gan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Composite Coatings ◽  
Ceramic Coatings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Scanning Electron

Abstract Ceramic coatings were prepared on the surface of 7050 highstrength aluminum alloy using micro-arc oxidation in an aluminate electrolyte with added graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron, and electrochemical measurements were used, respectively. The addition of 9 g · L-1 of graphene to the electrolyte decreased the micro-pore size of the composite coatings and improved the density. In addition, with the addition of graphene, the roughness was the lowest, and the corrosion resistance was significantly improved.

Microstructure and properties of rare earth CeO2-doped graphene composite coatings prepared by MAO on AA7050

2020 ◽  
Vol 111 (11) ◽  
pp. 923-930
Author(s):  
Yu Zong ◽  
Renguo Song ◽  
Tianshun Hua ◽  
Siwei Cai
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Composite Coatings ◽  
High Strength ◽  
Ceramic Coatings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Doped Graphene ◽  
Micropore Size

Abstract In this paper, ceramic coatings were prepared on the surface of 7050 high strength aluminum alloy using a micro-arc oxidation process in a silicate electrolyte combined with the rare earth element cerium or graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, and electrochemical measurements were used, respectively. It was shown that the micropore size of the composite coatings, which mainly consisted of α-Al2O3 and γ-Al2O3, decreases and the density improved with the simultaneous addition of 4 g · L-1 of CeO2 and 10 g · L-1 of graphene to the electrolyte. In addition, with the addition of CeO2 and graphene, the roughness was the lowest and the corrosion resistance was significantly improved.

Micro Arc Oxidation of AZ91 Magnesium Alloy – Effect of Organic Compounds in the Electrolyte

2014 ◽  
Vol 353 ◽  
pp. 217-222 ◽  
Author(s):  
Namik Kemal Gozuacik ◽  
Mert Altay ◽  
Murat Baydogan
Keyword(s):  
Corrosion Resistance ◽  
Coating Thickness ◽  
Electrochemical Corrosion ◽  
Organic Chemicals ◽  
X Ray Diffraction ◽  
Az91 Magnesium Alloy ◽  
Micro Arc Oxidation ◽  
Az91 Magnesium ◽  
Alloy Effect ◽  
Thickness Measurements

AZ91 Mg alloy was micro arc oxidized under constant electrical parameters in silicate based and phosphate based electrolytes with and without addition of organic chemicals, namely Hexamethylenetetramine (HMTA), TRIS (hydroxymethyl) aminomethane (THAM) and Glycerol in two different concentrations. Following oxidation, samples were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), coating thickness measurements, hardness measurements and electrochemical corrosion tests. Results showed that coating layers mainly consisted of MgO, Mg2SiO4 and MgF2 for silicate based electrolytes, and MgO for phosphate based electrolytes. Incorporation of organic chemicals into electrolyte composition did not change the type of the phases in the coating. However, when they are added in silicate based electrolytes, pore density and coating thickness are reduced and pore size is increased. On the other hand, there is no significant change in surface morphology when organic chemicals are added in phosphate based electrolyte. In the view point of corrosion resistance, organic chemicals did not enhance corrosion resistance of the samples oxidized in silicate based electrolytes, but exhibited some increment in corrosion resistance of the samples oxidized in phosphate based electrolytes.

Influence of Na2SiO3 Concentration on the Corrosion Behavior of TC4 Ceramic Coatings

2014 ◽  
Vol 971-973 ◽  
pp. 85-88
Author(s):  
Yun Long Zhang ◽  
Cheng Hai Li ◽  
Ming Hu ◽  
Yu Min Zhang
Keyword(s):  
Corrosion Resistance ◽  
Phase Composition ◽  
Sodium Silicate ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Ceramic Coatings ◽  
Coating Properties ◽  
Silicate Content ◽  
Micro Arc Oxidation ◽  
Oxidation Technology

The micro-arc oxidation technology were utilized to fabricated the ceramics coating in order to improve the corrosion resistance of Ti–6Al–4V alloy (TC4). The sodium silicate solution was introduced into the electrolyte solution for increasing the coating properties. The effect of the sodium silicate content on the phase composition, surface morphology and potentiodynamic polarization behavior was investigated. The results showed that the increase of Na2SiO3 concertration was benefit to improve corrosion resistance of the MAO coating of TC4 alloy. Key words: Micro-arc oxidation, Ceramic Coatings, Corrosion Resistance.

Micro Arc Oxidation of AZ91 Mg Alloy for Improved Corrosion Resistance

2011 ◽  
Vol 312-315 ◽  
pp. 877-881 ◽  
Author(s):  
H.G. Yavuz ◽  
M. Gunyuz ◽  
Isa Metin Ozkara ◽  
Murat Baydogan ◽  
Huseyin Cimenoglu
Keyword(s):  
Corrosion Resistance ◽  
Surface Topography ◽  
Xrd Analysis ◽  
Processing Parameters ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
Corrosive Solution ◽  
Weight Losses ◽  
Before And After ◽  
Micro Arc Oxidation

AZ91 Mg alloy was subjected to the micro arc oxidation process by using different processing parameters. Following oxidation, surface topography and qualitative phase analysis were made by tabletop digital microscopy and X-ray diffraction (XRD) analysis. In order to evaluate the relative corrosion resistance of the samples that were oxidized in different parameters, the samples were immersed in a corrosive solution for 6 days and the weight losses before and after the corrosion tests were compared. Relative corrosion resistance of the samples was evaluated on the basis of surface topography.

Microstructure Characteristics of Fe-xCr-C Hardfacing Alloys

2012 ◽  
Vol 472-475 ◽  
pp. 165-168
Author(s):  
Lin Zong ◽  
Zheng Jun Liu
Keyword(s):  
Solid Solution ◽  
Optical Microscopy ◽  
Arc Welding ◽  
Room Temperature ◽  
Gas Tungsten Arc Welding ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure Characteristics ◽  
Gas Tungsten Arc ◽  
Gtaw Process

A series of Fe-xCr-C hardfacing alloys were successfully fabricated on a substrate of 20g steel by gas tungsten arc welding (GTAW) process. These claddings were disigned to observe hypoeutectic, near-eutectic, and hypereutectic structures with various Cr3C2 and M7C3 carbides at room temperature. According to X-ray diffraction(XRD) and optical microscopy (OM), the hypoeutectic and eutectic composites include the Fe-Cr solid solution(α+A) and Cr3C2 carbides. Hypereutectic structures consist of α+A+M+M7C3 respectively. The cladding of hypereutectic microstructure with great amounts of primary M7C3 carbides had the highest hardness of the all conditions.

Effects of Interaction of (NaPO3)6 and NaH2PO4 on Ca/P of MAO Bio-Ceramic Coating of ZK60 Mg Alloy

2013 ◽  
Vol 745-746 ◽  
pp. 21-27
Author(s):  
Cui Ling Du ◽  
Jing Chen ◽  
Bin Bin Cao ◽  
Lei Xu ◽  
Sheng Lu
Keyword(s):  
Corrosion Resistance ◽  
Ceramic Coating ◽  
Energy Dispersive Spectrometer ◽  
Mg Alloy ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Orthogonal Experiments ◽  
Micro Arc Oxidation ◽  
Evolution Phase

Micro-arc oxidation (MAO) process was conducted on ZK60 Mg alloy in a basic biologic electrolyte composed of silicate by addition of (NaPO3)6 and NaH2PO4. The microstructural evolution, phase composition and in vitro corrosion resistance of the coating were investigated by means of scanning electron microscopy (SEM) coupled with an energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results revealed that bioactive elements Mg, Ca, P and Si were remained in the bio-ceramic coating which can be prepared in suitable biologic electrolyte. For the interaction of (NaPO3)6 and NaH2PO4 , the Ca/P molar ratio of the coating in the optimized biologic electrolyte reached to 1.24 by L9 (34) orthogonal experiments. Compared with the bare ZK60 Mg alloy, the corrosion resistance of the optimized sample in 37 Ringers solution was improved by 4 orders.

Weldability of High-Mn Austenitic Twinning-Induced Plasticity (TWIP) Steel Microalloyed with Nb

MRS Advances ◽  
2017 ◽  
Vol 2 (62) ◽  
pp. 3899-3908 ◽  
Author(s):  
I. Mejía ◽  
H. Hernández-Belmontes ◽  
C. Maldonado
Keyword(s):  
Heat Affected Zone ◽  
Twip Steel ◽  
Research Work ◽  
Welding Process ◽  
X Ray Diffraction ◽  
Austenite Stability ◽  
Gas Tungsten Arc ◽  
Solution Condition ◽  
Gtaw Process ◽  
Arc Welding Process

ABSTRACTThe objective of this research work is to study the weldability of a Nb microalloyed TWIP steel through welding nuggets generated by Gas Tungsten Arc Welding process. Weldability was examined by microstructural changes in the fusion zone (FZ) and heat affected zone (HAZ) using light optical metallography (LOM), segregation in the nuggets was evaluated using elemental mappings of chemical analysis by Scanning Electron Microscopy and Electron Dispersive Spectroscopy (SEM-EDS), phase transformations were evaluated using X-ray diffraction (XRD) and the hardness properties were examined using Vickers microhardness testing (HV25). Experimental results show that microstructure of welding nuggets consists of austenitic dendritic grains in the FZ and equiaxed grains in the HAZ. FZ width and HAZ grain growth tend to increase as the heat input increases. Additionally, the studied Nb-containing TWIP steel showed segregation in the FZ, where Mn and Si segregated in the interdendritic regions, while Al and C preferentially segregated in dendritic areas. In general, the data obtained by XRD indicated that GTAW process did not affect austenite stability. Finally, the welding nuggets of studied TWIP steel showed lower microhardness values than the as-solution condition (starting condition). However, the heat affected zone showed hardened areas, which are associated with NbC precipitation hardening.

Sign in / Sign up

Export Citation Format

Share Document