Mechanical performance and in-vitro biological behaviors of boronized Ti6Al4V/HA composites synthesized by microwave sintering

Abstract

The boronized Ti6Al4V/hydroxyapatite (HA) composites were synthesized by microwave sintering of the mixture of Ti6Al4V, HA and TiB2 powders at 950–1100 °C for 30 min, with an emphasis on the effects of sintering temperature on the properties of the resulting composites. It was found that at temperatures lower than 1050 °C, the composite specimens were not well sintered, causing high porosities in the composites. At 1050 °C, the Ti6Al4V grain boundaries were interconnected and intensified by TiB, resulting from the in situ reaction of TiB2 with Ti in the alloy. As the temperature increased to 1100 °C, there was apparent decomposition of HA to Ca3(PO4)2 which hindered complete densification of the composites. Because of these phase and microstructural transformations in association with the "lens effect" of microwave, the composite sintered at 1050 °C exhibited the optimal mechanical performance. Additionally, it possessed a small water contact angle, indicating its good hydrophilicity. By immersing this composite in the simulated body fluid (SBF), evident HA precipitation occurred on its surface, showing its great bioactivity. The findings confirmed that by controlling the sintering temperature properly, satisfactory mechanical performance and bioactivity can be obtained for this new type of biomaterial for implantation.