scholarly journals Improvement of pitting corrosion resistance for Al-Cu alloy in sodium chloride solution through equal-channel angular pressing

2011 ◽  
Vol 21 (4) ◽  
pp. 307-313 ◽  
Author(s):  
Dan SONG ◽  
Ai-bin MA ◽  
Jing-hua JIANG ◽  
Ping-hua LIN ◽  
Liu-yan ZHANG
Keyword(s):  
Corrosion Resistance ◽  
Sodium Chloride ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Angular Pressing ◽  
Cu Alloy ◽  
Pitting Corrosion Resistance

Effect of severe plastic deformation by ECAP on corrosion behaviour of aluminium alloy AA 7075

2016 ◽  
Vol 81 (2) ◽  
pp. 55-61 ◽  
Author(s):  
M. Ilieva ◽  
R. Radev
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Corrosion Behaviour ◽  
Chloride Concentration ◽  
Chloride Ions ◽  
Angular Pressing ◽  
Pitting Corrosion Resistance ◽  
Aa 7075

Purpose: The present study compares the corrosion behaviour of overaged AA 7075 before and after equal channel angular pressing ECAP in two media, containing chlorides, in order to answer the question how grain refinement of aluminium alloys influences their corrosion properties.Design/methodology/approach: The effect of equal channel angular pressing ECAP on corrosion behaviour of aluminium alloy AA 7075 was studied in two water solutions, containing chloride ions: 1) 0.01 M Na2SO4 with addition of 0.01%Cl-, and 2) 3g/l H2O2 and 57g/l NaCl. The changes in electrochemical characteristics, provoked by grain size refinement after equal channel angular pressing ECAP, were found using potentiodynamic polarisation. Steady state potential, corrosion potential, corrosion current density; breakdown (pitting) potential of overaged and deformed by equal channel angular pressing ECAP aluminium alloy AA 7075 were measured.Findings: In the environment with lower chloride concentration equal channel angular pressing ECAP process led to increase in pitting corrosion resistance and in the medium with higher chloride concentration - to decrease in pitting corrosion resistance. That way grain refinement does not demonstrate a uni-directional influence on corrosion resistance of AA 70775.Research limitations/implications: The results suggest the possibility for development of materials having the same chemical composition but with different corrosion resistance to different environments.Originality/value: The paper presents the corrosion behaviour of ultrafine-grained aluminium alloy AA 7075 and the influence of the chloride ions concentration in the corrosion medium on this behaviour.

Study on Electroless Ni-P Deposit on W-Cu Alloy and its Anti-Corrosion Mechanism

2008 ◽  
Vol 373-374 ◽  
pp. 240-243 ◽  
Author(s):  
Long Hao ◽  
Ye Ming Zhang ◽  
Chao Yang ◽  
Hua Zhu ◽  
Xu Hui Mao ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Sodium Chloride ◽  
Potentiodynamic Polarization ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Alloy Coating ◽  
Corrosion Mechanism ◽  
Alloy Substrate ◽  
Cu Alloy ◽  
Electroless Ni

With suitable pretreatment, a compact and even nickel-phosphorus alloy coating was obtained on W-Cu alloy by electroless deposition from solutions containing nickel sulphate as a source of nickel and sodium hypophosphite as the reducing agent and a source of phosphorus. The Ni-P coating was normally prepared from acidic baths at high temperature of the order of 90oC with the pH of 4.8 and it was smooth and uniform and exhibited high crystal refinement and high microhardness and superior corrosion resistance. The microhardness, adhesion and corrosion resistance mechanism of Ni-P deposit were studied. The microhardness of the Ni-P alloy deposit increases greatly by tempering at various temperatures. The Ni-P deposit has a strong adhesive force with W-Cu alloy substrate checked by thermal shock test and scribe test. The anti-corrosion ability of Ni-P coating and its anti-corrosion mechanism were measured using immersion experiment and potentiodynamic polarization techniques. The results showed that the corrosion resistance of Ni-P coating was higher than that of W-Cu alloy substrate in the 10vol.% sulfuric acid, monitoring sweat solution and 3.5wt.% sodium chloride solution. The anti-corrosion mechanism of electroless Ni-P coating immersed in 3.5wt.% sodium chloride solution was studied using potentiodynamic polarization techniques. The surface micromorphological morphology and structure of the Ni-P coating were investigated using Scanning Electronic Microscope (SEM) and X-ray Diffraction (XRD). The results indicated that the Ni-P alloy coating consisted of microcrystals and it was amorphous in structure, and the electrochemical measurement showed passive film formed on Ni-P coating during immersion test in the 3.5wt.% sodium chloride solution.

scholarly journals Effect of Equal Channel Angular Pressing on the Pitting Corrosion Resistance of Aluminum-Copper Alloy

2010 ◽  
Vol 61 (1) ◽  
pp. 50-57
Author(s):  
In-Joon SON ◽  
Hiroaki NAKANO ◽  
Satoshi OUE ◽  
Shigeo KOBAYASHI ◽  
Hisaaki FUKUSHIMA ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Copper Alloy ◽  
Angular Pressing ◽  
Pitting Corrosion Resistance ◽  
Aluminum Copper Alloy

Effect of Equal Channel Angular Pressing on the Pitting Corrosion Resistance on the Aluminum Alloys with/without Anodization

2010 ◽  
Vol 638-642 ◽  
pp. 1989-1994 ◽  
Author(s):  
Hiroaki Nakano ◽  
In Joon Son ◽  
Satoshi Oue ◽  
Shigeo Kobayashi ◽  
Hisaaki Fukushima ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Formation Rate ◽  
Oxide Films ◽  
Mg Alloy ◽  
Angular Pressing ◽  
Ecap Process ◽  
Pitting Corrosion Resistance ◽  
Al Oxide

The effect of equal-channel angular pressing (ECAP) on the pitting corrosion resistance of Al (AA1100) and Al-Mg (AA5052) alloy with anodization and without was investigated by means of polarization curves in solutions containing 300 ppm or 0.6 mol/L of Cl- and by surface analysis. In Al and Al-Mg alloy without anodization, the potentials for pitting corrosion were evidently shifted to the noble direction by ECAP process, indicating that this process improves resistance to pitting corrosion. SEM observation revealed that the pitting corrosion occurred near the impurity precipitates and the size of impurity precipitated decreased with ECAP process. The time-dependence of corrosion potential and the polarization resistance determined by AC impedance technique suggested that the formation rate of Al oxide films was increased with ECAP process. The improvement in pitting corrosion resistance of Al and Al-Mg by ECAP seems to be attributable to the decrease in the size of impurity precipitates and the increase in the formation rate of Al oxide films. On the other hand, the time required for initiating pitting corrosion of anodised Al was longer with ECAP than without, indicating improvement in the pitting corrosion resistance by application of ECAP. However, the pitting corrosion of anodized Al-Mg alloy occurred earlier with ECAP than without, showing that the corrosion resistance was worse with ECAP than without. In anodized Al-Mg alloy, cracks occurred in the anodic oxide films during initial corrosion and the cracks were larger with ECAP than without. It is assumed that the pitting corrosion was promoted by the cracks due to the higher internal stress resulting from ECAP.

Effect of Equal-Channel Angular Pressing on the Pitting Corrosion Resistance of Al Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 487-492 ◽  
Author(s):  
In-Joon Son ◽  
Hiroaki Nakano ◽  
Satoshi Oue ◽  
Shigeo Kobayashi ◽  
Hisaaki Fukushima ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Formation Rate ◽  
Electrochemical Techniques ◽  
Mg Alloy ◽  
Al Alloy ◽  
Angular Pressing ◽  
Ecap Process ◽  
Pitting Corrosion Resistance

The effect of equal-channel angular pressing (ECAP) on the pitting corrosion resistance of Al and Al-Mg alloy was investigated by means of polarization curves in solutions containing 300 ppm of Cl- and by surface analysis. The potentials for pitting corrosion of Al and Al-Mg alloy were evidently shifted to the noble direction by using the ECAP process, indicating that this process improves resistance to pitting corrosion. This increase in resistance seems to be attributable to the increase in formation rate of Al oxide films due to the increase in grain boundary with ECAP. The pitting corrosion resistance of Al and Al-Mg alloy anodized galvanostatically in H2SO4 solution after ECAP was also investigated using electrochemical techniques. The pitting corrosion resistance of Al and Al-Mg alloy was remarkably improved by anodizing. However, the pitting corrosion resistance of anodized Al-Mg alloy was better without ECAP than with ECAP.

Effect of Equal Channel Angular Pressing and Annealing on Corrosion Resistance of Al-Cu Alloy

2013 ◽  
Vol 803 ◽  
pp. 226-229
Author(s):  
Da Ran Fang ◽  
Chun Liu ◽  
Feng Fang Liu
Keyword(s):  
Corrosion Resistance ◽  
Low Temperature ◽  
Equal Channel Angular Pressing ◽  
Annealing Treatment ◽  
Coarse Grained ◽  
Nacl Solution ◽  
Angular Pressing ◽  
Cu Alloy ◽  
Low Temperature Annealing ◽  
Ultrafine Grained

Al-3.9wt.%Cu alloy was subjected to equal channel angular pressing (ECAP) and subsequent low temperature annealing treatment, and the corrosion resistance of the samples was investigated by potentiodynamic polarization measurements in 3.5% NaCl solution. The results show that the corrosion rate of the ultrafine-grained alloy increases, in comparison with the coarse-grained alloy. Meanwhile, it is noted that the corrosion resistance of the alloy subjected to ECAP can be improved by relief annealing.

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