Magnetron sputtered freestanding MgAg films with ultra-low corrosion rateTuesday (18.06.2019) 17:00 - 17:15
Biodegradable materials are of great interest for temporary medical applications. The functional stability of each implant type has to be ensured, thus leading to different retention times . As a consequence, specific corrosion rates are needed for the different applications. Magnesium (Mg) and Mg alloys can be used as biodegradable material. Silver (Ag) is known for its antibacterial properties and as an alloy constituent it allows the control of the corrosion rate .
In this study MgAg freestanding films which are fabricated by a combination of UV lithography, sacrificial layer technique and magnetron sputtering are investigated in terms of the corrosion properties and the microstructure . The Ag concentration was varied between 2 and 10 wt% Ag. The corrosion rate was determined by potentiodynamic polarisation measurements in Hanks´ balanced salt solution. The microstructure was investigated using X-ray diffraction and scanning electron microscopy. The obtained results show that it was possible to obtain a single phase material with up to 6 wt% Ag. The alloys showed a preferential orientation in  direction with small grains in the range of a 100 nm up to a few µm. MgAg alloys with 6 wt% Ag showed the lowest corrosion rate (CR=0.040 ±0.010 mm/a) which was by a factor of 2.9 lower than pure Mg (CR=0.116±0. 023 mm/a). At concentration of 10 wt% Ag precipitates are formed, which increase the corrosion rate (CR=2.27±0.463 mm/a) due to the formation of galvanic cells by a factor of 19.6 compared to pure magnesium.
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