麻豆淫院

Researchers from IMDEA Materials, in conjunction with the Helmholtz-Zentrum Hereon Institute of Surface Science and Meotec GmbH, have undertaken the first-ever comparison of corrosion resistance in Mg and Zn bioalloys produced by extrusion and additive manufacturing.

The study, which paves the way for safer, longer-lasting biodegradable implants, showed that plasma electrolytic oxidation (PEO) surface treatment improves corrosion resistance across all tested samples.

In a first for the field of bioabsorbable metals, the researchers conducted a pioneering comparison of the corrosion resistance of WE43 magnesium and Zn1Mg zinc alloys produced via extrusion and Laser Powder Bed Fusion (LPBF).

in Surface and Coatings Technology, the study is the first to use electrochemical testing in a buffered saline solution to compare how these two manufacturing routes affect the degradation of these clinically relevant biodegradable metals.

"To our knowledge, this is the first time that these two manufacturing techniques have been compared in terms of corrosion resistance for these materials," said first author Guillermo Dom铆nguez.

The results show that the LPBF-fabricated samples corroded significantly faster than their extruded counterparts. In WE43, this was linked to yttrium oxide particles present in the LPBF samples, which weakened the protective effect of the corrosion layer.

In Zn1Mg, the higher corrosion rate of the LPBF samples was attributed to an increased volume of eutectic phases, which accelerated microgalvanic degradation.

A eutectic phase is a microstructural feature formed when two elements solidify together at a specific ratio and temperature. An increased volume of eutectic phases creates more interfaces with the Zn matrix, forming numerous microgalvanic cells that accelerate localized corrosion. This speeds up overall material degradation.

To counteract this, the team applied a plasma electrolytic oxidation (PEO) surface treatment.

"To enhance corrosion resistance, a PEO process was applied to the samples," explained Dom铆nguez. "This treatment formed the expected oxide layer that improved protection across all tested materials compared to their untreated counterparts."

Interestingly, for Zn1Mg, the LPBF samples actually outperformed the extruded ones after PEO treatment.

"However, the WE43MEO LPBF specimens showed high corrosion rates despite PEO treatment, which was linked to heterogeneities in oxide layer thickness. In contrast, PEO treatment had the opposite effect on Zn1Mg samples, where LPBF specimens demonstrated greater corrosion resistance than the extruded ones," he added.

This disparity was tied to phosphorus-rich protective layers formed during surface modification, leading to higher phosphorus content in the LPBF PEO layer, which promoted the formation of inert phosphate phases, stabilizing the protective oxide layer.

The experimental component of the research was carried out by Dom铆nguez during a research stay at the Helmholtz-Zentrum Hereon Institute of Surface Science as part of the Horizon Europe BIOMET4D project, coordinated by IMDEA Materials Institute.

The samples were fabricated by project partners, Meotec GmbH, while the collaboration with Dr. Carsten Blawert's Department of Functional Surfaces at Hereon provided access to state-of-the-art electrochemical testing equipment.

By controlling how these materials are manufactured and treated, researchers can optimize their behavior inside the body, reducing risks and improving patient outcomes.