Effects of Interaction of (NaPO_3)_6 and NaH_2PO_4 on Ca/P of MAO Bio-ceramic Coating of ZK60 Mg Alloy

摘要

Micro-arc oxidation (MAO) process was conducted on ZK60 Mg alloy in a basic biologic electrolyte composed of silicate by addition of (NaPO_3)_6 and NaH_2PO_4. The microstructural evolution, phase composition and in vitro corrosion resistance of the coating were investigated by means of scanning electron microscopy (SEM) coupled with an energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results revealed that bioactive elements Mg, Ca, P and Si were remained in the bio-ceramic coating which can be prepared in suitable biologic electrolyte. For the interaction of (NaPO_3)_6 and NaH_2PO_4 , the Ca/P molar ratio of the coating in the optimized biologic electrolyte reached to 1.24 by L_9 (3~4) orthogonal experiments. Compared with the bare ZK60 Mg alloy, the corrosion resistance of the optimized sample in 37°C Ringer's solution was improved by 4 orders.