Research On Biodegradable Material Of Magnesium And Its Alloys For Coronary Artery Stent

Permanent implants may cause potential suffering for patients, such as mismatches in behaviour between the implant and the body as well as physical irritation and chronic inflammatory reactions. And they cannot degrade spontaneously and a second surgical procedure is usually needed to remove the metal implants from the body after the tissues have completely healed. Repeated surgery increases the cost as well as patient morbidity. In this respect, biodegradable magnesium alloys can be a potential solution. This study designed the new type of non-toxic magnesium alloys, preparaed the alloys and tested the mechanical properties, biocompatibility and biodegradable properties. Obersved the microstructure, phase composition and Ca/P morphology after immersion in SBF by XRD, SEM and EDS methods, and evaluated the corrosion properties by electro-chemical method and immersion in SBF method. The results indicated that:1. The alloys which designed are non-toxic Mg-Sn binary systerm which containingα-Mg and Mg₂Sn phases.2. The microhardness of magnesium alloys increases with the Sn content increasing, and the best tensile properties occurred when Sn addition is 5%. It is means that tensile properties will be better with Sn increasing until 5%, and when it is over over 5%, the tensile properties will be worse again.3. The surface of magnesium alloys can deposite Ca/P layer like flower, needlelike and particle texture after immersion in SBF when the content of Sn is equal or lesser than 3% which is demonstrate good biocompatibility. But when the content of Sn is equal or greater than 4%, the surface of magnesium alloys cannot deposite Ca/P layer any more unless increase the biocompatibility by alkali treatment or alkali-heat treatment.4. The pH value of immersion solution is rising and the weight of samples is lost while the magnesium alloys dissolve in SBF. And the performance of biodegradable behavior can be aggravation and the degradation rate can be increase with the content of Sn increasing. However, the maximum of pH value and sample weight loss rate can be decreased after different alkali treatment or alkali-heat treatment which can improve the biodegradable behavior of magnesium alloys to some extent.5. It is demonstrated that MS0 alloy had good biocompatibility and biodegradable properties. But combined the mechanical properties MS3 alloy is the best for biodegradable material.