Interface Structure between Ti-Based Bulk Metallic Glasses and Hydroxyapatite Ceramics Jointed by Hydrothermal Techniques

Abstract

The authors successfully formed a bond between bioactive hydroxyapatite (HA) ceramics and titanium (Ti)-based bulk metallic glasses (Ti₄₀Zr₁₀Cu₃₆Pd₁₄: BMG) through a growing integrated layer (GIL) to develop a new type of biomaterial. The GILs were formed on the BMG surfaces by hydrothermal-electrochemical (HE) techniques. The BMG substrates were treated in a 5 mol/L NaOH solution at 90°C for 600, 2400 and 7200 seconds while a constant electric current of 50 mA/mm² was maintained between the electrodes. Then the BMG disks with the GIL and a powder mixture of calcium phosphate di-hydrate (CaHPO₄·2H₂O) and calcium hydroxide (Ca(OH)₂) were simultaneously treated with an autoclave for hydrothermal hot-pressing (HHP) (150°C, 40 MPa, 7.2 ks). Direct bonding between the HA ceramics and the BMG disks could be achieved through the above processing method. Scanning electron microscopy observations was conducted around the interface between BMG and HA. The bonding model of the bonding BMG and HA was suggested. The bonding was achieved through the amorphous nano-meshed layer consumption during the HHP processing. Sufficient thickness of GIL derived from hydrothermal-electrochemical treatment for over 2.4 ks is needed for the bonding.