Abstract
The utilization of Mg alloys for biomedical applications is so far underexplored due to the accelerated corrosion hampering patient recovery post implantation. Here, we explore the effectiveness of corrosion reduction of an AZ31 alloy in Simulated Body Fluid when coated with a 40 nm sputtered TiO2 layer and compare it to a similar coating made by Atomic Layer Deposition (ALD). Potentiodynamic polarization and hydrogen evolution experiments were performed on coated samples having different surface roughness and 3D topologies. Interestingly, ALD layers reduce corrosion current density by 94% on Ra = 118.6 ± 5.1 nm and 93% on Ra = 4794.3 ± 49.4 nm, whereas sputtered only by 84% on Ra = 118.6 ± 5.1 nm and 60% on Ra = 4794.3 ± 49.4 nm. Particularly on 3D aspects, the ALD coatings are superior, where a scaffold of 85% porosity with 1 mm pore sizes released 68% lower hydrogen compared to the sputtered counterparts. We relate these observations to the higher surface integrity, adhesion strength and lower line-of-sight restrictions of ALD compared to sputter deposition. The results can be interesting for researchers and practitioners aiming to make Mg alloys more commonplace as temporary metallic implant materials.
Highlights
The ageing of our society paired with increasing obesity raises the demand for orthopedic interventions requiring the implantation of medical devices [1]
Liu et al reported a three orders of magnitude decrease in the corrosion current density of a 10 nm ZrO2 coated AZ31 Mg alloy [40], while Yang et al reported a two orders of magnitude corrosion current density reduction with a 40 nm ZrO2 layer on a MgSr alloy [42]. Taking these results one step further, we explore the corrosion reduction of Atomic Layer Deposition (ALD) layers on realistic AZ31 alloy implant surfaces and compare the results with those obtained by sputter technique
We provided new insights into the corrosion performances of ALD coated AZ31 Mg alloy and compared corrosion protection performances of ALD and sputtered biocompatible TiO2 coatings
Summary
The ageing of our society paired with increasing obesity raises the demand for orthopedic interventions requiring the implantation of medical devices [1]. Among these procedures, the number of orthopedic implantations is growing the fastest [2]. The materials currently used in orthopedic surgery are usually permanent metallic materials, such as stainless steel, titanium, and cobalt‐chromium alloys [3] due to their high strength and good corrosion resistance [3,4,5]. Additional surgeries are required to remove the implant causing an increase in costs to the health care system, as well as emotional stress to the patient
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