Regulation of corrosion damage of magnesium alloys through the use of vacuum zirconium coatings

Abstract

Magnesium alloys have a unique combination of properties in terms of specific strength, modulus of elasticity and biocompatibility, which allows them to be considered as one of the most promising materials for use as temporary bioresorbable implants capable of being replaced by bone tissue in the process of gradual dissolution in the human body, thereby eliminating the need for repeated surgical intervention to remove the implant after healing. In this regard, the world scientific community pays much attention to works aimed at developing methods for controlling the corrosion damage of magnesium alloys. The present study demonstrates that such a precision control can be realized using vacuum zirconium coatings, while Zr itself is already actively used in medicine. It has been shown that the application of a zirconium coating on the MA14 (ZK60) alloy, which is currently considered as one of the possible candidates for use in medical practice, with thicknesses of 0.4 and 0.8 μm, can reduce the corrosion damage estimated by the hydrogen yield, based on 110 hours per 1.3 and 1.6 times, respectively. The favorable effect of the zirconium coating on the resistance to corrosion processes is confirmed by the results obtained using a laser confocal microscope: a decrease in both the total corroded area and the depth of corrosion damage was recorded in three-dimensional images of the sample surface. In addition, in the work using scanning electron microscopy, a comprehensive study of the obtained coatings is presented, which made it possible to characterize its structure and chemical composition. The adhesion characteristics of the coating were evaluated by scratching on a tester and showed that for a coating with a thickness of 0.8 μm, fracture is observed at an indentation load of the conical indenter of the order of 0.5 N.

On the Corrosion Fatigue of Magnesium Alloys Aimed at Biomedical Applications: New Insights from the Influence of Testing Frequency and Surface Modification of the Alloy ZK60

“…As has been shown recently in [76], the deposition of the thin film of Zr on the surface of the specimen of the same ZK60 alloy reduced the corrosion rate in Ringer's solution from about 13.8 to 10.5 mm/y when the coating thickness was 0.4 ± 0.2 μm and to 8.5 mm/y when the thickness of the protective coating was increased to 0.8 ± 0.2 μm. A significant (by orders of magnitude) reduction in the corrosion rate of AZ31 magnesium alloy has been observed after deposition of protective ceramic layers either by plasma electrolytic oxidation (PEO) [77,78] or atomic layer deposition techniques (ALD) [79,80].…”

Attaining High Functional Performance in Biodegradable Mg-Alloys: An Overview of Challenges and Prospects for the Mg-Zn-Ca System

“…The observed features are attributed to the difference in the corrosion resistance of ZK60 and ZX10 (c.f., Table 2 and refs. [ 96 , 235 ]; the corrosion rate in ZX60 is roughly an order of magnitude higher than that in ZX10): the lower the corrosion resistance of the material, the less clearly the fatigue features are seen on the fracture surface (c.f., Figure 12 b,d).…”