Study of compaction-free fabrication of topologically ordered functionally graded iron-hydroxyapatite-zinc biodegradable composite implants

Metals like iron, zinc and magnesium are gaining the attention of researchers in the field of biomedical implants owing to their good mechanical and biodegradable properties. However, there are various problems associated with each of these materials like very fast or very slow degradation rate, stress shielding, poor mechanical properties, etc. These problems could be resolved by fabricating composite and functional biomaterials, combining the advantages of two or more materials into single biomaterial. However, till date no process has been developed to fabricate topologically ordered and functionally graded composite biodegradable implants. The present work focuses on the development of a novel approach utilizing 3D printing, pressureless microwave sintering and casting to fabricate topologically ordered and functionally graded composite biodegradable implants. Four different kinds of composite biomaterials were fabricated by combining iron, hydroxyapatite and zinc with density and porosity varying in range of 1.95–5.36 g/cm³ and 28.37–73.99%, respectively. Dimensional deviation in fabricated samples as compared to designed dimensions was found to be in range of 10.33–18.44%. Compression tests were performed for all fabricated samples, and compressive strength and modulus of elasticity were found to vary from 17.62 to 102.32 MPa and 186.12 to 2452.20 MPa, respectively. The corrosion analysis of fabricated samples was done to evaluate the degradation behaviour in simulated body fluid. The degradation rate was found to be varying in range of 1.68–4.33 mm/year.