In Vitro Degradation And Biocompatibility Of Fe-35Mn Alloy Prepared By Spray Forming

Metallic materials are widely used in orthopedics and other hard tissues' repairment,but most of the metal implants are permanent and need to be removed,which doesn't only increase the medical costs,but also add to patients' suffering.Therefore,biodegradable materials have attracted much attention.Iron has certain biodegradability,good biocompatibility and proper mechanical properties,so it has become a potential biodegradable biomaterial.However,iron and most iron alloys are magnetic,leading to failure of medical tests such as nuclear magnetic resonance.In addition,the general degradation of ferroalloys can not meet the clinical application requirements.Its biological toxicity is also a considering point.Spray forming technology is a rapid solidification and forming technology developed in recent years.The obtained material has the characteristics of porous and homogeneous tissue composition,and the effect of improving porosity on improving the degradation performance of the material can not be ignored.In order to make ferroalloy paramagnetic,while maintaining the degradation rate,this project prepared Fe-Mn alloy with Mn content up to 35% by spray forming process.Compared with forged and casted Fe-35 Mn alloy,immersion test in Hank's solution(composition curve,pH curve,weight loss test)was performed.Physical property test(magnetic,surface topography,tensile strength and impact toughness),electrochemical experiments(potentiodynamic scanning method),other methods to explore spray forming process on physical properties of Fe-35 Mn alloy and in vitro degradation experiment were carried out;Cytotoxicity test was conducted to explore compatibility of sprayed Fe-35 Mn alloy.The main findings are as follows:(1)Tensile test and impact test show that spray forming process can improve mechanical properties of Fe-35 Mn alloy.The results of magnetic properties show that Fe-35 Mn alloy has paramagnetic properties and does not affect MRI or other medical tests.(2)Static immersion test and scanning electron microscopy(SEM)show that spray forming process has better effect on improving the degradation rate of Fe-35 Mn alloy than casting and forging process.The corrosion morphology is obviously more uniform too.Fe and Mn can form solid solution,raising the corrosion rate of pure iron.The porous features formed by spray forming have characteristics of self-catalytic corrosion reaction to further improve the corrosion rate of Fe-35 Mn alloy.(3)Analysis of the composition of the corrosives shows that the degradation products deposited on the surface of the Fe-35 Mn alloy are mainly composed of elements beneficial to the human body such as oxygen,iron,manganese,sodium,phosphorus and calcium.Cytotoxicity test further shows that the addition of Mn can improve the biocompatibility of Fe.The higher ion concentration formed by the faster corrosion rate won't cause more severe cytotoxic effects.In addition,Pore enhances the body's metabolism and substance interactions to improve biocompatibility.