Biodegradation Behavior of Coated As-Extruded Mg–Sr Alloy in Simulated Body Fluid

Abstract

As-extruded Mg-Sr alloy, a kind of promising biodegradable biomedical material, was coated using micro-arc oxidation and also using a phosphate conversion coating. The corrosion behaviors were investigated using Hanks' solution. The corrosion of the as-extruded Mg-Sr alloy became more serious with increasing immersion time; that is, the corrosion pits became more numerous, larger and deeper. The micro-arc oxidation coating and the phosphate conversion coating were effective in improving the corrosion resistance of the as-extruded Mg-Sr alloy. The micro-arc oxidation coating was much more effective. Moreover, the as-extruded Mg-Sr alloy and the coated as-extruded Mg-Sr alloy exhibited lower corrosion rates than the as-cast Mg-Sr alloy and the corresponding coated as-cast Mg-Sr alloy, indicating that the corrosion properties of the coated samples are dependent on their substrates. The finer microstructure of the substrate of the as-extruded condition corroded much slower. The corrosion resistance of the coated Mg-Sr alloy depended on the coating itself and on the microstructure of the substrate.

Study on a Novel Biodegradable and Antibacterial Fe-Based Alloy Prepared by Microwave Sintering

“…Figure 4 a shows the polarization curves of the microwave-sintered pure Fe and Fe-8Cu. The corrosion potential ( E corr ) and corrosion current density ( i corr ) were evaluated by the Tafel extrapolation method [ 28 , 29 ]. The polarization curve of the microwave-sintered pure Fe had an obvious current platform in the anode region, as shown in Figure 4 a, which indicated that the pseudo-passivation film might be formed on the surface, affecting the corresponding degradation rate [ 21 ].…”

Biodegradation, Antibacterial Performance, and Cytocompatibility of a Novel ZK30-Cu-Mn Biomedical Alloy Produced by Selective Laser Melting

“…The EDS spectra in Point 1 and Point 2 in Figure 7C confirmed that the regular corrosion layers and the discontinuous white products on the corroded surface of SLMed ZK30-0.2Cu-0.8Cu specimens contained “O, Mg, Ca, and P” and “O and Mg,” respectively. The Ca and P elements were present on the corroded surface, indicating that Ca-P compounds precipitated on the surface of the hydroxide corrosion layers as the corrosion continued[ 31 ]. The EDS spectra of Point 3 in Figure 7A confirmed that the corrosion products on the corroded surface of SLMed ZK30-0.2Cu contained “O and Mg,” similar to the EDS spectra of Point 2.…”

Surface Treatment of Zn-Mn-Mg Alloys by Micro-Arc Oxidation in Silicate-Based Solutions with Different NaF Concentrations

“…With the formation of a large number of bubbles on the surface of the metal sample, the metallic luster of the substrate gradually disappears, and a very thin oxide coating is formed [54,55]. During the corrosion process, the internal layer is considered as the main protective layer of the MAO coating, which is a continuous protective screen to prevent charge transfer and subsequent degradation [56]. The holes and microcracks produced in the process of MAO provide a channel for the corrosive medium to enter the substrate and form a local galvanic cell.…”

“…The inner layer can provide a very poor physical isolation of the Zn substrate from the corrosive medium at the beginning of immersion [33]. Due to the me- During the corrosion process, the internal layer is considered as the main protective layer of the MAO coating, which is a continuous protective screen to prevent charge transfer and subsequent degradation [56]. The holes and microcracks produced in the process of MAO provide a channel for the corrosive medium to enter the substrate and form a local galvanic cell.…”