Characterization of the Micro-Arc Coatings Containing β-Tricalcium Phosphate Particles on Mg-0.8Ca Alloy

Abstract

The characterization of the microstructure, morphology, topography, composition, and physical and chemical properties of the coatings containing β-tricalcium phosphate (β-TCP) particles deposited by the micro-arc oxidation (MAO) method on biodegradable Mg-0.8Ca alloy has been performed. The electrolyte for the MAO process included the following components: Na 2 HPO 4 •12H 2 O, NaOH, NaF, and β-Ca 3 (PO 4) 2 (β-TCP). The coating morphology, microstructure, and compositions have been studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). With increasing of the MAO voltage from 350 to 500 V, the coating thickness and surface average roughness of the coatings increased linearly from 6 to 150 µm and from 2 to 8 µm, respectively. The coating deposited at 350 V had more homogeneous porous morphology with numerous pores similar by sizes (2-3 µm) than the coatings formed at 450-500 V. The β-TCP isometric particles were included in the coating surface. The XRD recognized the amorphous-crystalline structure in the coatings with incorporation of the following phases: β-TCP, α-TCP, MgO (periclase) and hydroxyapatite (HA). The corrosion experiments showed that the biodegradation rate of the Mg-0.8Ca alloy coated by calcium phosphates is almost 10 times less than that of uncoated alloy.

Plasma Electrolytic Oxidation of Metals and Alloys

“…The present Special Issue covers 10 papers: Six articles [1][2][3][4][5][6] discuss the Plasma Electrolytic Oxidation PEO of titanium [2,4,6] and its alloys [1,3,5], two papers talk about the PEO processing of aluminum alloys [7] and composites [8], and one on magnesium alloys [9]. The tenth paper is a review regarding soft sparking issues in PEO [10].…”

“…Sedelnikova et al [9] studied biodegradable magnesium alloy Mg-0.8Ca after PEO/MAO (Micro-Arc Oxidation) treatment. Modification of the biodegradable magnesium alloy using the MAO in electrolytes with the addition of beta-tricalcium phosphate (β-TCP) particles was performed to improve its biocompatibility and corrosion resistance.…”

Comparative Study of the Structure, Properties, and Corrosion Behavior of Sr-Containing Biocoatings on Mg0.8Ca

“…The rate of coatings dissolution and their biological properties depend on the substances that the coatings are consisted of. The most common biocoatings are based on the calcium orthophosphates such as hydroxyapatite (HA) [22,25,27,40] and tricalcium phosphate (TCP) [34] or include their combinations. Hydroxyapatite has the lowest dissolution rate in body fluids.…”

“…Hydroxyapatite has the lowest dissolution rate in body fluids. Acid calcium orthophosphates such as tricalcium phosphate [34], brushite [41], and monetite [42] dissolve faster [43]. Thus, by combining various phases, it is possible to control the dissolution rate of biocoatings and thereby to manage the bioresorption of magnesium alloys.…”

Degradation Behavior of Micro-Arc Oxidized ZK60 Magnesium Alloy in a Simulated Body Fluid

“…To our knowledge, most studies focus on the corrosion behavior of MAO coatings on AZ91 or AZ31 Mg alloys (whose chemical composition contain Al, well-known as a main inducing element to Alzheimer's disease) in SBF [37,38]. Some researchers have chosen to develop their own self-designed Mg alloys with bio-safe alloying elements [39][40][41], taking a great deal of R&D time and cost. ZK60 (Mg-Zn-Zr) Mg alloy is not only commercially available, but its alloying element Zn is a trace element essential to the human body, and Zr (another alloying element)-based materials (e.g., ZrO, Zr-Cu-Al-Ag alloy, Zr-2.5Nb, Zr-1.5Nb-1Ta crystalline alloys, etc.)…”