Investigation on mechanical, in vitro corrosion, and biocompatibility behaviour of ZK61-10HA-2.5ES hybrid bio-composite for orthopaedic implant applications

Biodegradable implants are crucial for orthopaedic applications, as they eliminate the necessity for a secondary surgical procedure. This investigation adopts composite methodology by reinforcing ZK61 with hydroxyapatite (HA) and eggshell (ES) to fabricate Mg-based metal matrix composite using friction stir processing (FSP). The impact of introducing 10 wt% HA as a bioactive ceramic and 2.5 wt% ES as a green, low-cost reinforcement via FSP on mechanical performance, in vitro corrosion behaviour, and biocompatibility is reported. The microhardness and ultimate compressive strength of the ZK61-10HA-2.5ES composite (74.6 HV, 356 MPa) showed a ∼24% increase in microhardness and a ∼28% increase in UCS compared to ZK61 alloy (60.1 HV, 278 MPa). The corrosion rate of ZK61-10HA-2.5ES composite was assessed using electrochemical measurements and found a lower corrosion rate (1.05 mm/year) compared to ZK61 alloy (3.63 mm/year), which aligned with the results obtained from immersion. After 1 and 3 days of incubation, the MTT assay revealed that the ZK61-10HA-2.5ES composite exhibited grade 0 non-cytotoxic response to MG-63 cells, indicating its promising potential for orthopaedic applications.