Microstructure and properties of co-continuous (β-TCP+MgO)/Zn-Mg composite fabricated by suction exsorption for biomedical applications

The biomedical co-continuous (β-TCP+MgO)/Zn-Mg composite was fabricated by infiltrating Zn-Mg alloy into porous β-TCP+MgO using suction exsorption technique. The microstructure, mechanical properties and corrosion behaviors of the composite were evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion test. It was found that the molten Zn-Mg alloy had infiltrated not only into the pores but also into the struts of the porous β-TCP+MgO scaffold to form a compact composite. The Zn-Mg alloy contacted to the β-TCP+MgO scaffold closely, and no reaction layer can be found between the alloy and the scaffold. The compressive strength of the composite was as high as 244 MPa, which was about 1000 times higher than that of the original porous β-TCP+MgO scaffold and 2/3 of the strength of the Zn-Mg bulk alloy. The electrochemical and immersion tests in simulated body fluid (SBF) solution indicated that the corrosion resistance of the composite was better than that of the Zn-Mg bulk alloy. The corrosion products on the composite surface were mainly Zn(OH)₂. Appropriate mechanical and corrosion properties indicated that the (β-TCP+MgO)/Zn-Mg composite fabricated by suction exsorption would be a very promising candidate for bone substitute.