Effect of sandblasting on the oxidation and corrosion behaviour of an oxide-dispersed strengthened (ODS) FeCrAl alloy

摘要

Metallic biomaterials are preferred for replacements of the hard tissues since they are the most suitable to withstand the mechanical loads. For same components the higher surface roughness is preferred to increase the adherence and anchorage between the implant and the bone. In this work sandblasting prior to the oxidation is used to increase the surface roughness of the oxide dispersion strengthened (ODS) FeCrAl alloy. The effect of sandblasting on its oxidation and corrosion behaviour is studied. As a comparison, polished samples are also studied. The alloy treated at 1100°C generates a dense α-alumina layer which thickness increases with increasing exposure time, being the values somewhat lower for the sandblasted samples. Impedance diagrams obtained for sandblasted samples preoxidised for 1 and 3 h show impedance values at the lowest frequency two orders of magnitude lower than those for polished samples. This decrease in the impedance value can be attributed to the presence of paths or fine cracks in the alumina layer that communicate the aggressive medium with the metallic substrate. Spallation of the alumina layer in preoxidised sandblasted samples has been detected by electrochemical impedance spectroscopy for treatment times of 10 and 100 h. Despite this loss of the scale integrity, the corrosion behaviour is good.