Characterization and corrosion studies of fluoride conversion coating on degradable Mg implants

Chiu, K. Y.; Wong, M.H.; Cheng, F. T.; Man, Hau Chung

doi:10.1016/j.surfcoat.2007.06.035

Cited by 339 publications

(170 citation statements)

References 23 publications

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“…Conversion coatings are widely studied as corrosion protection for magnesium and its alloys. Fluoride and calcium phosphate-based conversion coatings have a great potential of reducing the corrosion rate of biomedical magnesium implants [1][2][3][4][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Powder Metallurgy Processed Pure Magnesium Materials for Biomedical Applications

Zapletal

Březina

Krystýnová

et al. 2017

Metals

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Magnesium with its mechanical properties and nontoxicity is predetermined as a material for biomedical applications; however, its high reactivity is a limiting factor for its usage. Powder metallurgy is one of the promising methods for the enhancement of material mechanical properties and, due to the introduced plastic deformation, can also have a positive influence on corrosion resistance. Pure magnesium samples were prepared via powder metallurgy. Compacting pressures from 100 MPa to 500 MPa were used for samples' preparation at room temperature and elevated temperatures. The microstructure of the obtained compacts was analyzed in terms of microscopy. The three-point bending test and microhardness testing were adopted to define the compacts' mechanical properties, discussing the results with respect to fractographic analysis. Electrochemical corrosion properties analyzed with electrochemical impedance spectroscopy carried out in HBSS (Hank's Balanced Salt Solution) and enriched HBSS were correlated with the metallographic analysis of the corrosion process. Cold compacted materials were very brittle with low strength (up to 50 MPa) and microhardness (up to 50 HV (load: 0.025 kg)) and degraded rapidly in both solutions. Hot pressed materials yielded much higher strength (up to 250 MPa) and microhardness (up to 65 HV (load: 0.025 kg)), and the electrochemical characteristics were significantly better when compared to the cold compacted samples. Temperatures of 300 • C and 400 • C and high compacting pressures from 300 MPa to 500 MPa had a positive influence on material bonding, mechanical and electrochemical properties. A compacting temperature of 500 • C had a detrimental effect on material compaction when using pressure above 200 MPa.

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Section: Introductionmentioning

confidence: 99%

Characterization of Powder Metallurgy Processed Pure Magnesium Materials for Biomedical Applications

Zapletal

Březina

Krystýnová

et al. 2017

Metals

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“…Several treatments to protect magnesium against corrosion have been proposed such as magnesium purification [11], fluoride conversion coatings [12], alloying with other elements, anodizing, [1,11,13], etc. Several studies [14][15][16][17][18][19][20] have shown that the corrosion behaviour of Mg alloys is significantly dependent on the microstructure and particularly on the amount and distribution of the intermetallic phases and the grain size.…”

Section: Introductionmentioning

confidence: 99%

Corrosion behaviour of AZ31 magnesium alloy with different grain sizes in simulated biological fluids☆

et al. 2010

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The comparative study of the corrosion behaviour of the AZ31 magnesium alloy with different grain sizes immersed in simulated body fluids was made in chloride solutions (8g/L) and Phosphate Buffer-containing Solution (PBS). The influence of the immersion time was also analysed. Electrochemical techniques such as the open circuit potential, polarization curves, current transients and electrochemical impedance spectroscopy, complemented with scanning electron microscopy and energy dispersive spectroscopy were used. Immediately after the immersion in the corrosive media the corrosion resistance was similar for both grain sizes of the AZ31 alloy and higher in 2 NaCl solutions than in PBS. However, this corrosion behaviour was reversed after longer periods of immersion due to the stabilizing of the corrosion products of MgO and/or Mg(OH) 2 with P-containing compounds. These P-compounds contribute to a higher level of protection by hindering the aggressive action of chloride ions. The best corrosion behaviour of the AZ31 alloy was obtained for the finest grain alloy associated with the highest transfer resistance value, after long periods of immersion in PBS.

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“…[72] There are only a few types of solution used for immersion tests: 0.9% NaCl solution saturated with Mg(OH) 2 called PSS (physiological saline solution), [61] PBS solution (phosphate-buffered saline), [72] fetal bovine serum, [4] and the rather aggressive Hanks' solution. [73] The first stage of corrosion is characterized by the fastest changes in pH value and H 2 release. In laboratory studies, this only takes a few hours, [62] 24 h, [52] or at least 100 h [13] to stabilize the pH value and the amount of H 2 released.…”

Section: Corrosionmentioning

confidence: 99%

“…With a more prolonged immersion time, the samples with larger pore diameters were found to degrade faster than those with smaller pores, because of easier fluid flow within the pores. [4] MgF 2 has an electrochemically more stable surface than untreated Mg. [73] The period of Mg immersion in HF to form a conversion coating that is dense and free of cracks is 24 h. The corrosion resistance is more than one order of magnitude better, due to the fluoride coating. Moreover, MgF 2 -coated magnesium corrodes more uniformly.…”

Section: Corrosionmentioning

confidence: 99%

Current Status and Recent Developments in Porous Magnesium Fabrication

et al. 2017

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A significant number of studies have been dedicated to the fabrication and properties of metallic foams. The most recent research is focused on metals with low weight and good mechanical properties, such as titanium, aluminum, and magnesium. Whereas the first two are already fairly well studied and already find application in industry, magnesium currently remains at the research stage. The present review covers the studies conducted on fabrication techniques, surface modifications, and properties of porous structures made of magnesium and its alloys.

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Characterization and corrosion studies of fluoride conversion coating on degradable Mg implants

Cited by 339 publications

References 23 publications

Characterization of Powder Metallurgy Processed Pure Magnesium Materials for Biomedical Applications

Characterization of Powder Metallurgy Processed Pure Magnesium Materials for Biomedical Applications

Corrosion behaviour of AZ31 magnesium alloy with different grain sizes in simulated biological fluids☆

Current Status and Recent Developments in Porous Magnesium Fabrication

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