Production of Biodegradable Metal Foams by Powder Metallurgy Method

In this study, highly porous biocompatible and biodegradable zinc, iron and magnesium alloy foams were fabricated for temporary implant and scaffold applications. Specimens with open porous structure were fabricated by powder metallurgy based space holder method. Mg, Fe and Zn are the main bioabsorable metals. Mg alloys biodegrade too fast with H₂ evolution. Biodegradation rate of Fe alloys is too slow, and by-products remain inside the body. Zn alloys show biodegradation rates in the middle of Mg and Fe alloys, and their biodegradation by-products are bioresorbable. Here several Fe, Zn, and Mg alloys were manufactured, and comparatively characterized. Effects of alloying elements on biodegradation, corrosion and mechanical properties were investigated separately. As the mechanical properties of temporary implants must decrease slowly, the variation of mechanical properties with time in the foams was investigated. Corrosion performance was tested in simulated body fluid. Biodegradation rate was investigated by using weight loss and metal ion release measurements. The corrosion and biodegradation rates of Zn specimens were lower than in Mg specimens and higher than in Fe specimens. Fe²⁺, Zn²⁺ and Mg²⁺ ion release amounts were lower than the upper limit for humans.