Synthesis and Characterization of Ti-Enhanced F75/HA Functionally Graded Materials Fabricated by Powder Metallurgy

Functionally graded materials (FGMs) are a highly advanced class of biomaterials with graded structure and properties, enabling the fabrication of physiologically and mechanically compatible materials for use in various medical devices. This study aims to produce a functional-grade material based on a cobalt-chromium-molybdenum alloy (F75) reinforced with 4% titanium (Ti) and hydroxyapatite (HA). This will enhance the material's mechanical properties, corrosion resistance, and bioactivity, making it suitable for use as a bone substitute. The natural eggshells were washed, burnt, and chemically processed to form hydroxyapatite with a Ca/P proportion of 1.67. FTIR showed that phosphate and OH groups were separate, and XRD showed that the substance formed nano-HA (peaks at 25.9 ° and 49.5 ° with a crystallite size of 14-56 nm), which showed the purity of the substance. Five-layer graded materials (FGM) were created using the prepared HA. With an elastic modulus of 34.37±0.49 GPa, which is closer to that of natural bone and lessens stress shielding, FGM performed the best. Additionally, its corrosion rate dropped to 0.413±0.015 mm/y, and its hardness rose to 375.63±17.8 HV. In terms of biology, FGM exhibited a high bio-sedimentation rate (90%) during immersion, and the number of bacterial colonies decreased from 1.34 ± 0.02 × 108 CFU/ml to 0.060 ± 0.020 × 108 CFU/ml, yielding an inhibition rate of more than 95%. Titanium's ability to reduce crystalline defects and form a stable Tio₂ layer that enhances corrosion resistance and bioactivity is responsible for these advancements. This study demonstrates the effectiveness of titanium in developing functionally graded materials for use as bone implants.