Phosphate Conversion Coating on Diecast AZ91D and Its Corrosion Resistance

2005 ◽  
Vol 488-489 ◽  
pp. 819-822 ◽  
Author(s):  
Wan Qiu Zhou ◽  
Da Yong Shan ◽  
En Hou Han ◽  
Wei Ke
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Magnesium Alloys ◽  
Polarization Curve ◽  
Immersion Test ◽  
Amorphous Structure ◽  
Conversion Coating ◽  
Test Results ◽  
Complex Phosphate

A phosphate conversion coating was deposited on diecast AZ91D magnesium alloys, the film was a complex phosphate containing Mg and Al,which showed amorphous structure. Corrosion resistance of conversion coating in 3.5%NaCl was investigated by polarization curve. It was showed that the anodic branch of polarization curve for the phosphate conversion coating presented typical passivation characteristic. Immersion test results showed that the corrosion rate of phosphate conversion coating was less than that of chromate Dow7 film.

The Corrosion Resistance of the Mg-Al-Ca-Sr Sand Casting Magnesium Alloys

2012 ◽  
Vol 326-328 ◽  
pp. 255-260 ◽  
Author(s):  
Andrzej Kiełbus ◽  
Tomasz Rzychoń ◽  
Joanna Michalska ◽  
Michal Stopyra
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
Immersion Test ◽  
Corrosion Layer ◽  
Sand Casting ◽  
Nacl Solution ◽  
Effective Barrier ◽  
Corrosion Rates

In this paper, the corrosion resistance of two sand-casting creep resistant magnesium alloys Mg-9Al-1.5Ca-0.3Sr and Mg-9Al-2.2Ca-0.8Sr in the salt environment has been investigated. Specimens of each alloy has been immersed in 3.5% NaCl solution at room temperature and successively taken out after 1, 2, 4, 5 and 9 days. After immersion test, the microstructure and the appearances of the corroded structure were examined. The corrosion rates of both investigated alloys increased lineally with increasing the exposure time in both solutions. Mg-9Al-1.5Ca-0.3Sr alloy exhibits the higher corrosion rate during the immersion test than Mg-9Al-2.2Ca-0.8Sr. The corrosion layer of both alloys consists of MgO, MgOH and phases containing Cl, Na, Al and Ca. The increase of Ca content in the Mg-9Al-2.2Ca-0.8Sr alloy improved the corrosion resistance due to the formation of the reticular (Mg,Al)2Ca phase, which acted as an effective barrier against corrosion.

scholarly journals Structure and Corrosion Behavior of TiO2 Thin Films Deposited by ALD on a Biomedical Magnesium Alloy

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 70
Author(s):  
Aneta Kania ◽  
Magdalena M. Szindler ◽  
Marek Szindler
Keyword(s):  
Thin Films ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Magnesium Alloys ◽  
Corrosion Behavior ◽  
Atomic Layer ◽  
Immersion Test ◽  
Mg Alloys ◽  
Tio2 Films ◽  
Tio2 Thin Films

Magnesium alloys have been investigated as temporary biomaterials for orthopedic applications. Despite their high osseointegration and mechanical (bone-like) properties, Mg alloys quickly degrade in simulated physiological media. Surface coatings can be deposited onto Mg alloys to slow the corrosion rate of these biomaterials in chloride-rich environments. TiO2 films show high potential for improving the corrosion resistance of magnesium alloys. This article presents the structural observations and corrosion behavior of TiO2 thin films deposited onto a MgCa2Zn1Gd3 alloy using atomic layer deposition (ALD). Surface morphologies were observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and Raman analysis of the deposited TiO2 films was also carried out. The corrosion behavior of the uncoated alloy and the alloy coated with TiO2 was measured in Ringer’s solution at 37 °C using electrochemical and immersion tests. The microscopic observations of the TiO2 thin films with a thickness of about 52.5 and 70 nm showed that the surface morphology was homogeneous without visible defects on the TiO2 surface. The electrochemical and immersion test results showed that the thin films decreased the corrosion rate of the studied Mg-based alloy, and the corrosion resistance was higher in the thicker TiO2 film.

Catechol/polyethyleneimine conversion coating with enhanced corrosion protection of magnesium alloys: potential applications for vascular implants

2018 ◽  
Vol 6 (43) ◽  
pp. 6936-6949 ◽  
Author(s):  
Hao Zhang ◽  
Lingxia Xie ◽  
Xiaolong Shen ◽  
Tengda Shang ◽  
Rifang Luo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Surface Modification ◽  
Magnesium Alloys ◽  
Corrosion Protection ◽  
Conversion Coating ◽  
Good Corrosion Resistance ◽  
Potential Applications

A catechol/polyethyleneimine conversion coating on a MgZnMn alloy possessed good corrosion resistance. Heparin was further grafted on it and this showed the potential for surface modification of magnesium-based vascular implants.

scholarly journals Improvement of bio-compatible AZ61 magnesium alloy corrosion resistance by fluoride conversion coating

2016 ◽  
Vol 60 (5) ◽  
pp. 132-138 ◽  
Author(s):  
J. Drábiková ◽  
F. Pastorek ◽  
S. Fintová ◽  
P. Doležal ◽  
J. Wasserbauer
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Simulated Body Fluid Solution ◽  
Conversion Coating ◽  
Az61 Magnesium Alloy ◽  
Wrought Magnesium Alloy ◽  
Consequent Effect ◽  
Materials Used ◽  
Short Time

Abstract Magnesium and its alloys are perspective bio-degradable materials used mainly due to their mechanical properties similar to those of mammal bones. Potential problems in utilization of magnesium alloys as bio-materials may relate to their rapid degradation which is associated with resorption problems and intensive hydrogen evolution. These problems can be eliminated by magnesium alloys surface treatment. Therefore, this work aims with analysis of the influence of fluoride conversion coating on corrosion characteristics of magnesium alloy. Unconventional technique by insertion of wrought magnesium alloy AZ61 into molten Na[BF4] salt at temperature of 450 °C at different treatment times was used for fluoride conversion coating preparation. The consequent effect of the coating on magnesium alloy corrosion was analyzed by means of linear polarization in simulated body fluid solution at 37 ± 2 °C. The obtained results prove that this method radically improve corrosion resistance of wrought AZ61magnesium alloy even in the case of short time of coating preparation.

scholarly journals Effect of Native Oxide Film on Commercial Magnesium Alloys Substrates and Carbonate Conversion Coating Growth and Corrosion Resistance

Materials ◽  
2014 ◽  
Vol 7 (4) ◽  
pp. 2534-2560 ◽  
Author(s):  
Sebastián Feliu, Jr. ◽  
Alejandro Samaniego ◽  
Elkin Bermudez ◽  
Amir El-Hadad ◽  
Irene Llorente ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Oxide Film ◽  
Magnesium Alloys ◽  
Conversion Coating ◽  
Native Oxide ◽  
Coating Growth

Properties of Conversion Coating of Magnesium Alloys by a Phosphate-Permanganate Solution

2005 ◽  
Vol 488-489 ◽  
pp. 665-668 ◽  
Author(s):  
Shu Sen Wu ◽  
Ming Zhao ◽  
Ji Rong Luo ◽  
You Wu Mao
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Adhesion Force ◽  
Conversion Coating ◽  
Resistance Test ◽  
Az91d Alloy ◽  
Conversion Coatings ◽  
Good Adhesion ◽  
Better Than

A chromium-free conversion coating for AZ91D magnesium alloys has been obtained by using a phosphate-permanganate solution. Examinations have been carried out on the conversion coating for morphology, composition, adhesion force and corrosion resistance. Results show that the conversion coatings are relatively uniform and continuous, with thickness from 7µm to 10µm. They exhibit good adhesion to matrix and have some non-penetrate tiny holes on the surface. The main elements of the conversion coating of AZ91D alloy are Mg、O、P、K、Al、Mn. Results of corrosion resistance test indicate that the corrosion resistance of the conversion coating by phosphate-permanganate solution is in match to that of the conversion coating formed in a chromate solution, but for the corrosion resistance after painting, the former is better than the later.

Surface Modification on Magnesium Alloys by Coating with Magnesium Fluorides

2005 ◽  
Vol 475-479 ◽  
pp. 505-508 ◽  
Author(s):  
T. Ohse ◽  
Harushige Tsubakino ◽  
Atsushi Yamamoto
Keyword(s):  
Corrosion Resistance ◽  
Surface Modification ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Az31 Alloy ◽  
Immersion Test ◽  
Low Ph ◽  
Nacl Solution ◽  
Filiform Corrosion ◽  
A New Technique

A new technique has been developed for improving corrosion resistance on magnesium alloys. Specimens of AZ31 magnesium alloy were dipped into molten salt of NaBF4 at 723 K for various times, and then cooled, rinsed with water, and dried in air. Corrosion resistance in the surface treated specimens was evaluated by salt immersion test using 1 % NaCl solution as a time for occurring filiform corrosion. On an un-treated AZ31 alloy, the time for starting the filiform corrosion was about 1.2 ks, while on the surface treated specimen, the time was prolonged into about 1300 ks. Moreover, the surface treated specimen showed corrosion resistance in low pH solutions, such as 1 % HNO3 and HCl solutions.

Preparation and Characterization of Polylactic Acid Coating on the Surface of Magnesium Alloy

2015 ◽  
Vol 814 ◽  
pp. 132-136 ◽  
Author(s):  
Xian Yang Hua ◽  
Mei Feng He ◽  
Xiao Qin Zhou
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance Spectroscopy ◽  
Magnesium Alloy ◽  
Impedance Spectroscopy ◽  
Corrosion Rate ◽  
Polylactic Acid ◽  
Magnesium Alloys ◽  
Electrochemical Impedance ◽  
Hank’S Solution ◽  
Acid Coating

Magnesium is one of the elements necessary for the body, is the man behind the body’s content of potassium ions within the cell are involved in a series of metabolic processes in vivo, including the formation of bone cells , acceleration of bone healing ability. Resulting from the good mechanical properties and biocompatibility, magnesium alloy is used in medical intervention material, but the high corrosion rate of magnesium alloys is the main drawback to their widespread use, especially in biomedical applications. There is a need for developing new coatings that provide simultaneously corrosion resistance and enhanced biocompatibility. In this work the medical magnesium alloy surface are dipped and coated with polylactic acid, so that obtain a dense uniform polylactic acid coating. And the corrosion resistance of the coating is studied in order to obtain controlled degradable and corrosion resisted magnesium alloy biological material. This paper mainly studies the influence of different concentrations of polylactic acid coating on AZ91D magnesium alloy corrosion resistance. The coated samples were immersed in Hank’s solution and the coating performance was studied by electrochemical impedance spectroscopy and scanning electron microscopy. This research is about the influence of the coating on the corrosion resistance of magnesium alloy through the open circuit potential, polarization curves, electrochemical impedance spectroscopy and Mott-Schottky. The results confirmed that the polylactic acid slow down the corrosion rate of AZ91D magnesium alloys in Hank’s solution. And along with the increase of poly lactic acid concentration, the corrosion resistance of magnesium alloys is improved. There is a wide variation of the corrosion morphology magnesium alloy AZ91D specimens after the surface modification using polylactic acid coating, compared with the unmodified.

Fast Electroless Ni-P Coating on AM60 Magnesium Alloy at Low Bath Temperature

2011 ◽  
Vol 418-420 ◽  
pp. 756-759 ◽  
Author(s):  
Guo Bing Mao
Keyword(s):  
Growth Rate ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Electroless Plating ◽  
Corrosion Test ◽  
Bath Temperature ◽  
Test Results ◽  
Electroless Ni

The Ni-P coatings were deposited on AM60 magnesium alloy by electroless plating process without or with accelerators. Without accelerators, the deposition rate is slow and required high bath temperature to obtain compact coating. There have many defects on the surface of the Ni-P coatings which deposited at high bath temperature. The composite accelerators were introduced into the bath for improving the growth rate and the quality of the Ni-P coating. Uniform, with no pores or cracks, “cauliflower-like” structure and complete Ni-P coatings were deposited only taken 20 min with additives at low bath temperature. The XRD result indicates that the structure of the Ni-P coating is amorphous nickel. The corrosion test results indicated that the corrosion resistance of this coated AM60 magnesium alloys increases distinctly as compared to bare alloys.

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