Structural, Mechanical and Corrosion Properties of Mg/SiO2 and MgO/SiO2 Multilayer Coatings for Magnesium Implant Devices

Abstract

In this study, Mg/SiO2 and MgO/SiO2 multilayer coatings with bilayer thicknesses (Λ) 10, 20, 40, 100, 200 and 1000 nm were deposited on glass substrates using DC and reactive pulsed DC magnetron sputtering processes. The aim of these coatings is to control the initial degradation and provide mechanical strength to magnesium implant during handling and installation. The initial thickness calibrations and deposition rates optimization were conducted using stylus profilometer. After deposition of the multilayer coatings, the values of their bilayer thicknesses (Λ) were obtained from X-ray reflectometery. The mechanical properties, surface morphology and roughness of multilayer coatings were studied using nanoindentation, SEM and AFM respectively. The nanoindentation results showed higher hardness of MgO/SiO2 multilayer coatings compared to single layer Mg. The roughness analyses showed improved roughness for bilayer thicknesses (Λ) less than 20 nm. It was observed from the SEM images that SiO2 coatings has pores. By adding Mg and/or MgO in the form of multilayers improves the pores significantly. The Mg/SiO2 multilayer coatings showed controlled degradation rate when immersed in saline solution compared to the monolithic SiO2 coating. In conclusion, conditions for depositing Mg/SiO2 and MgO/SiO2 multilayer coatings has been optimized. Alternating brittle SiO2 ceramic layers with soft and ductile Mg layers significantly improved the hardness of the Mg coating. Hardness of multilayer coatings can be fine-tuned by modifying bilayer thicknesses. Significant improvement in the corrosion and mechanical properties of the multilayer coatings can be used to protect surface of magnesium implant material during handling, storage and installation.

First-principles study of O2 and H2O adsorption on the Mg3Sb2(10−11) surface

“…It has been reported that, compared with MgO, Al 2 O 3 performs better in improving the corrosion resistance of a material. 34,35 It is natural to think that forming an Al 2 O 3 passivation layer may be more helpful for improving the performance stability of Mg 3 Sb 2 . Both theoretical calculations and experiments have demonstrated that Al as a donor dopant is compatible with the n-type thermoelectric transport of Mg 3 Sb 2 , but its contribution to the electron concentration is far lower than that of lanthanides and chalcogenides.…”

Fabrication of Mg/Al2O3 Nanolaminates using DC/PDC Magnetron Sputtering to Evaluate the Effect of Oxygen Content and Total Pressure for Deposition of Thin-Films

“…Deposition parameters are playing vital role in fabrication of right choice chemistry and morphology. Pulsed DC and Radio frequency magnetron sputtering is most widely used method for oxide or ceramic thin film depositions [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. For pure materials direct current magnetron sputtering is still the best choice [5,[16][17][18][19][20].…”