Degradation behaviour of selective laser melted CoCrMo alloys in H2O2-containing chloride solutions

H2O2 usually develops after implanting an implant of biomedical material in human body. Our study showed that H2O2 has dual effects on degradation behaviour of biomedical material depending on its concentration. As for a SLMed CoCrMo alloy, a critical concentration of H2O2 exists, below which the corrosion potential shifts positively as the concentration increases, facilitating the passive film formation; and above which, the film becomes less protective due to the change in composition of the film. The corrosion resistance of XOZ plane of the alloy is better than that of XOY plane due to less grain boundaries and secondary precipitates. •A critical concentration of H2O2 exists, below which the formation of passive film was facilitated with increasing concentration, and above which the change of passive film composition results in lower corrosion resistance.•The passive film formed in 9 g/L NaCl + 30 mM H2O2 mainly consist of oxide/hydroxide of Co, which is less protective than Cr2O3 formed in solutions without H2O2.•Corrosion resistance of XOZ plane of the tested SLMed CoCrMo alloy is larger than that of XOY plane due to less grain boundaries and secondary precipitates.