Corrosion and wear corrosion behaviour of a ceramic composite for use in biomedical applications

In view of the biocompatibility of both Si3N4 and TiN, it was reputed interesting to investigate the corrosion and wear corrosion behaviour of a ceramic Si3N4-35 vol % TiN composite in solutions simulating the composition of biological fluids. With this purpose, composite specimens were prepared and exposed to a 1% NaCl, in the absence and in the presence of 1% lactic acid. Tests were carried out under both corrosion and wear corrosion conditions and the results obtained were compared to those carried out on Ti6Al4V alloy, commonly used in biomedical applications. The morphology of the corrosion attack was investigated by SEM observations. The results show that under corrosion conditions the ceramic material exhibits corrosion rates comparable to those exhibited by the metallic material. However, under combined wear corrosion conditions the ceramic composite is definitely more corrosion resistant.