Corrosion behavior of pristine and added MgB₂ in Phosphate Buffered Saline Solution

We have obtained by Spark Plasma Sintering (SPS), dense samples of MgB₂ added with Ho₂O₃. Starting composition was (MgB₂)_0.975(HoO_1.5)_0.025 and we used addition powders with an average particle size below and above 100 nm. For Mg, pristine and added MgB₂ samples we measured potentiodynamic polarization curves in Phosphate Buffered Saline (PBS) solution media at room temperature. MgB₂ based composites show corrosion/ degradation effects. This behavior is in principle similar to Mg based alloys in the same media. Our work suggests that the different morphologies and phase compositions of the SPS-ed samples influence the interaction with corrosion medium; hence additions can play an important role in controlling the corrosion rate. Pristine MgB₂ show a significant improvement of the corrosion resistance, if compared with Mg. The best corrosion resistance is obtained for pristine MgB₂, followed by MgB₂ with nano-Ho₂O₃ and μ-Ho₂O₃ additions.