Characteristic Features of Corrosion Dissolution of a Model Biodegradable Implant Made of NZ30K Alloy + 0.1 wt.% Ag Clad with a Silver Layer in Ringer-Locke Solution

Introduction. In recent years, biodegradable magnesium alloy implants have been increasingly employed in traumatology for the surgical treatment of bone fractures. Their capacity to gradually degrade within the body eliminates the need for secondary removal surgeries. Problem Statement. The widespread clinical adoption of magnesium-based biodegradable implants has been limited by their uncontrolled corrosion behavior and the potential for adverse biological reactions during the healing process. Purpose. This study aims to determine the characteristic features of the corrosion dissolution of NZ30K + + 0.1 wt.% Ag alloy clad with a silver layer when exposed to Ringer-Locke solution. Materials and Methods. The corrosion behavior of NZ30K + Ag alloy samples, clad with a 1200 nm thick silver layer, has been examined in Ringer-Locke solution using electrochemical techniques. Corrosion damage has been characterized through optical and scanning electron microscopy. Results. The NZ30K + Ag alloy samples clad with a 1200 nm silver layer have undergone both contact and crevice corrosion in Ringer-Locke solution. This is reflected in the evolution of the corrosion potential Ecor during testing. Initially, the Ecor value shifts negatively at a rate of 0.06 mV/s — 1.5 and 1.8 times faster than that observed for the samples with coating thicknesses of 900 nm and 500 nm, respectively. Subsequently, the shift rate decreases to 0.014 mV/s, indicating a partial inhibition of crevice corrosion. This process gets stabilized at a steady-state Ecor = –1.426 V, at which selective dissolution of the surface occurs. Corrosion damage manifests itself as of pores and channels, characteristic of preferential degradation of the magnesium matrix. Conclusions. The study has revealed that the sample with a 1200 nm silver coating exhibits selective dissolution with localized pore formation. In contrast, the sample with a 900 nm coating has demonstrated significantly fewer and smaller corrosion sites. Based on these findings, NZ30K + Ag alloy implants with a 900 nm silver coating have been recommended for further clinical evaluation.