Corrosion studies related to suitability of permanent magnets for biomedical applications

The present paper explains the suitability of permanent magnetic alloys, Nd-Fe-B and SmCo5, for biomedical applications. The results revealed that the corrosion rate of the Nd-Fe-B alloy is about 23 times more than SmCo5 in simulated body fluid environments. The results also revealed that both alloys are unable to form protective oxide scales on their surfaces upon immersion in a simulated body fluid environment. Though the corrosion rate of the SmCo5 alloy is considerably low when compared to the Nd-Fe-B alloy, the corrosion rate is still high for use in biomedical applications. AC impedance results confirm the above findings. The studies also showed that the degradation of the Nd-Fe-B alloy takes place due to grain boundary corrosion, while pitting corrosion is the reason for degradation of the SmCo5 alloy. Finally, the necessity of surface engineering techniques for combating corrosion more effectively without affecting the magnetic properties, and thereby enhancing their exploitation and life in body fluid environments, has been highlighted. (C) 2002 Published by Elsevier Science Inc.