Influences of Tannic Acid Concentration on Properties of Micro-Arc Coatings Formed on AZ91 Magnesium Alloys

2012 ◽  
Vol 182-183 ◽  
pp. 297-301
Author(s):  
Shu Fang Zhang ◽  
Rong Fa Zhang ◽  
Tao Wang ◽  
Shun Shun Yao ◽  
Zhi Hua Chen
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Acid Concentration ◽  
Tannic Acid ◽  
Coating Properties ◽  
Micro Arc Oxidation ◽  
Az91 Magnesium ◽  
Solution Conductivity ◽  
Coating Color

Anodic coatings were prepared by micro-arc oxidation on AZ91 magnesium alloys with the addition of 0-8 g/L tannic acid. The influences of tannic acid concentration on the conductivity and coating properties were studied. The result shows that with the increase of tannic acid concentration, the solution conductivity decreases and the coating color becomes dark. In the solution with 4 g/L tannic acid, the obtained coatings are the most uniform and achieve the best corrosion resistance.

Effects of Calcium-Containing Electrolytes on Anodic Coatings Formed on AZ91 Magnesium Alloys

2014 ◽  
Vol 952 ◽  
pp. 43-46
Author(s):  
Shu Fang Zhang ◽  
Rong Fa Zhang ◽  
Biao Qu ◽  
Yin Feng Zheng
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Calcium Content ◽  
Coating Properties ◽  
Calcium Salts ◽  
Calcium Addition ◽  
Az91 Magnesium

Anodic coatings were prepared by micro-arc on AZ91 magnesium alloys in solutions with different calcium salts. The influence of calcium salts on the coating properties were studied. The result shows that anodic coatings formed in Ca (OH)2system has higher calcium content. When the Ca (OH)2concentrations is 2g/L, the Ca content is the highest, and the Calcium addition achieve the best corrosion resistance.

Influence of 8-hydroxyquinoline on properties of anodic coatings obtained by micro arc oxidation on AZ91 magnesium alloys

2012 ◽  
Vol 539 ◽  
pp. 249-255 ◽  
Author(s):  
R.F. Zhang ◽  
S.F. Zhang ◽  
N. Yang ◽  
L.J. Yao ◽  
F.X. He ◽  
...  
Keyword(s):  
Magnesium Alloys ◽  
Micro Arc Oxidation ◽  
Az91 Magnesium

Effects of Erbium Addition on the Corrosion Resistance and Microstructure of AZ91 Magnesium Alloy

2011 ◽  
Vol 194-196 ◽  
pp. 1221-1224 ◽  
Author(s):  
Zhong Jun Wang ◽  
Yang Xu ◽  
Jing Zhu
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Discontinuous Precipitation ◽  
Az91 Magnesium Alloy ◽  
Continuous Precipitation ◽  
Az91 Magnesium ◽  
Precipitation Phase

The microstructures and corrosion resistance of AZ91 and AZ91+0.5 wt.% erbium (Er) magnesium alloys were studied, respectively. The results show that the Er addition in scrap AZ91 magnesium alloy can improve the corrosion resistance, markedly. The discontinuous precipitation phase (DPP) for Mg17Al12was retarded and the amount of DPP was decreased by 41% due to the formation of Al8ErMn4phase during solidification. The amount of continuous precipitation phase (CPP) in grains was decreased by 8% because of the formation of Al7ErMn5phase during solidification.

Corrosion and Protection of Magnesium Alloys

2015 ◽  
Vol 1120-1121 ◽  
pp. 1078-1082 ◽  
Author(s):  
Yang Yang Lv ◽  
Ling Feng Zhang
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Automotive Industry ◽  
Physical And Mechanical Properties ◽  
Current Status ◽  
Strain Rates ◽  
Metallic Materials ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

Magnesium alloy as a green material in the 21st century, because of its excellent physical and mechanical properties of metallic materials as an ideal in the automotive industry, electronic industry and aviation, aerospace and other industries[1]. However, poor corrosion resistance of magnesium alloys become an important issue hinder application of magnesium alloys[2]. So magnesium alloy corrosion problems and the current status of research paper reviews several magnesium alloy protection methods at home and abroad, and also highlighted with our latest laser shock (LSP) study of AZ91 magnesium alloy at high strain rates of corrosion resistance results.

Effects of NaOH Concentration on Properties of Micro Arc Coatings on Magnesium Alloys

2012 ◽  
Vol 482-484 ◽  
pp. 909-913 ◽  
Author(s):  
Shu Fang Zhang ◽  
Rong Fa Zhang ◽  
Wen Kui Li ◽  
Yi Min Zhong
Keyword(s):  
Corrosion Resistance ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Magnesium Alloys ◽  
Environmental Scanning ◽  
Nacl Solution ◽  
Base Solution ◽  
Polarization Test ◽  
Micro Arc Oxidation ◽  
Scanning Electron

Anodic coatings were prepared by micro arc oxidation on AZ91HP in a base solution of 18 g/L Na2SiO3 ּ9H2Oand 4 g/L tannic acid with 5-20 g/l NaOH. The influence of NaOH concentration on final voltage and corrosion resistance were studied. The morphologies of anodic coatings were determined by environmental scanning electron microscope (ESEM). Potentiodynamic polarization test was performed in 3.5wt.% NaCl solution to evaluate the corrosion resistance of anodic coatings. The results show that the NaOH concentration has greatly effect on the final voltage, the compositions, thickness, morphologies and corrosion resistance. The corrosion resistance of anodic coatings is the best in the base solution containing 10 g/l NaOH.

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.

Study on Micro-Arc Oxidation Behavior of AZ91 Magnesium Alloy in Aluminate Environmentally Friendly Electrolyte

2020 ◽  
Vol 1003 ◽  
pp. 67-75
Author(s):  
Xian Ming Chen ◽  
Ying Ying Fan
Keyword(s):  
Corrosion Resistance ◽  
Electron Microscope ◽  
Magnesium Alloy ◽  
Oxide Film ◽  
Oxidation Behavior ◽  
Salt Spray ◽  
Alkaline Electrolyte ◽  
Az91 Magnesium Alloy ◽  
Micro Arc Oxidation ◽  
Az91 Magnesium

In aluminate alkaline electrolyte the effect of aluminate on the microstructure and properties and the MAO(micro-arc oxidation) behavior of micro-arc oxide film of AZ91 magnesium alloy was studied. Transmission electron microscope(TEM), energy dispersive spectrum (EDS), X-ray diffraction(XRD), salt spray test and scanning electron microscope(SEM)were used to analyze and characterize the structure and properties of the film. The results show that the concentration of aluminate has an important effect on the tank voltage, corrosion resistance, surface morphology and phase structure of micro-arc oxidation film. The corrosion resistance and film quality of the film were increased first and then decreased, but the surface roughness decreased first and then increased with the increase of aluminate concentration from 5g/L to 30g/L. At our work, the concentration of 10g/L aluminate electrolyte is most favorable to the formation of micro-arc oxide film.

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