Synthesis and in vitro degradation evaluation of the nano-HA/MgF2 and DCPD/MgF2 composite coating on biodegradable Mg–Ca–Zn alloy

Effect of Post-Treatment Techniques on Corrosion and Wettability of Hydroxyapatite-Coated Co–Cr–Mo Alloy

“…Electrolyte was prepared by mixing 0.42 mol/L Ca(NO 3 ) · 4H 2 O and 0.25 mol/L NH 4 H 2 PO 4 [16] with the Ca/P ratio being 1.67 in DI water with the pH value of 3.5 adjusted by adding HNO 3 and (CH 2 OH) 3 CNH 2 [20]. The electrolyte was rendered homogeneous by continuously stirring at 100 rpm for 24 h. The EPD process was performed by a regulated DC power supply (DYY-6C, BEIJING LIUYI) in a current density of 9 mA/cm 2 .…”

“…After coating with the calcium phosphate, the specimens were removed from the electrolyte solution, rinsed in distilled water and dried at (60 • C) for 24 h. Two different post-treatment methods were then employed to convert dicalcium phosphate dihydrate (DCPD) to crystalline HA. The first as-deposited sample was sintered at (800 • C) for 1 h in the vacuum furnace at 10 −5 torr [16], and the second one was immersed into the 0.1 mol/L NaOH solution at (70 • C) for 2 h [20]. After immersion, the samples were rinsed with distilled water and subsequently dried.…”

“…A three-electrode cell was used for electrochemical measurements, including a reference electrode [saturated calomel electrode (SCE)], counter electrode (graphite rod) and working electrode (the specimens). The tests were carried out in 500 mL of simulated body fluid (Kokubo solution [(mmol/L) 142 Na + , 5 K + , 2.5 Ca 2+ , 1.5 Mg 2+ , 4.2 HCO 3− , 147.8 Cl − , 1 HPO 2− 4 , 0.5 SO 2− 4 ]) with a pH of 7.6 and a temperature of (37 • C) [20]. The critical parameters, such as corrosion potential (E corr ) and corrosion current density (I corr ), were evaluated from the polarization curves.…”

“…Although there are many methods, such as pulsed laser deposition [12], plasma spray [13], solgel [14] and electrophoretic deposition (EPD) [7,[15][16][17], available to coat HA on metallic substrates, there are only two post-treatment methods that are commercially used: sintering posttreatment [15][16][17] and alkaline post-treatment [18][19][20]. Simple equipment, rapid formation and high efficiency have made EPD a preferable method for the coating of HA on biomaterials, such as stainless steel and titanium.…”

Fabrication and corrosion behavior of Si/HA nano-composite coatings on biodegradable Mg–Zn–Mn–Ca alloy

“…The corrosion current density (i corr ), corrosion potential (E corr ), cathodic Tafel slopes (β c ), anodic Tafel slopes (β a ) and the corresponding corrosion rate (P i ) of the specimens, extracted from the polarization curves, are shown in Table 3. The corrosion rate (P i ) of the samples, obtained from the corrosion current density, was calculated according to [37,38]:…”