High strength zinc composite with tungsten reinforcements as a potential biomaterial

There has been a significant interest in Zinc-based biomaterials on account of their biocompatibility as well as biodegradability. The low mechanical strength of pure Zinc has however limited its widespread application. In this work we report improvement in the strength of Zn brought about by the introduction of W as reinforcement. By employing a combination of powder metallurgy, casting and thermo-mechanical processing, bulk Zn-20 wt% W composite bearing a relative density of 98 % and flexural strength 100 % higher than that of pure Zn was produced. Potentiodynamic polarization tests in Hanks balanced salt solution revealed that the i_corr value of the composite was almost similar to that of Zn at 2.23 × 10⁻³ A/cm². X-ray photoelectron spectroscopy studies on the samples exposed to the electrolyte revealed the presence of a Zn based passivation layer in both Zn and the Zn-20W samples. In-vitro cytotoxicity tests revealed a similar cell response in Zn and Zn-20W samples. In the absence of a binary phase diagram for Zn and W, Miedema’s model was employed to understand the phase formation tendencies in the Zn-W system. X-ray diffraction studies showed that the Zn and W retained their elemental form within the composite despite the plethora of processing steps employed for its production.