Development Of Co-based Bulk Metallic Glasses As Potential Biomaterials

In this thesis, CoCrMo bulk metallic glasses（BMGs） were prepared as potential bio-implant materials by the combination method of fluxing treatment and J-quenching repaid solidification technique, and their thermal stability, corrosion resistance, concentrations of ion released and biocompatibility was investigated as compared to the common CoCrMo biomedical alloy（AFSM F75） and biomedical 316 L stainless steel（316L SS）. The main work includes the following two parts.In the first part of work, Co_80-x-yCr_xMo_yP₁₄B₆（x=5 y=5; x=5 y=10; x=10 y=10, all in at.%） BMGs with the maximum diameter of 1.5 mm have been developed as potential bio-implant materials by a combination method of fluxing treatment and J-quenching technique. In corrosion resistance researches, all of samples in both Hank’s solution（pH=7.4） and artificial saliva solution（pH=6.3） at 37 ℃ by electrochemical measurement. Compared the present Co-based BMGs with 316 L SS, the results indicates that the corrosion resistance of the present Co-based BMGs in the above two simulated body solution is much better than 316 L SS. Compared the present Co-based BMGs with ASTM F75, the results indicates that Co70Cr5Mo5P₁₄B6（denoted as Cr5Mo5） and Co65Cr5Mo10P₁₄B6（denoted as Cr5Mo10） in the above two simulated body solution is little worse than ASTM F75, while Co₆₀Cr₁₀Mo₁₀P₁₄B6（denoted as Cr10Mo10） is better than ASTM F75. In concentrations of ion released researches, we detected concentrations of metallic ion released after electrochemical measurements in both Hank’s solution and artificial saliva solution. The results indicates that concentrations of ion released from the present Co-based BMGs is lower than the released from ASTM F75. The biocompatibility of the specimens is evaluated through the in vitro test of NIH3T3 cells culture in the specimen extraction media for 1, 3, 5 and 7 days. The result indicates that the present Co-based BMGs exhibit no cytotoxicity to NIH3T3 cells. And the test result of the cell adhesion and growth on the surface of the specimens indicates that the present Co-based BMGs exhibit the better cell viability compared with ASTM F75 and 316 L SS biomedical alloys.In the second part of work, we substitute Co by Fe in Co₆₀Cr₁₀Mo₁₀P₁₄B6（denoted as Fe0） BMG, which has been developed in the first work and exhibit the best performance, in order to further improve the glass forming ability（GFA） and performance of this BMG. As a result, Co45Fe15Cr10Mo10P₁₄B6（denoted as Fe15） and Co30Fe30Cr10Mo10P₁₄B6（denoted as Fe30） BMGs are successfully prepared. Fe0, Fe15 and Fe30 have been characterized and studied following the same method as that in the first part of work, and so we can investigate the effect of the Fe substitution for Co on the performance of the present CoCrMo BMG. It indicates that the substitution of Co by Fe can effectively enhance the GFA of the present CoCrMo alloy, and the critical diameter of Fe30 reaches 2.0 mm. The corrosion resistance test shows that the corrosion resistance of the present CoFeCrMo BMGs in Hank’s solution decreases with the increase of the Fe substitution content for Co, while the adverse consequence is observed in the artificial saliva. Nevertheless, the Fe substitution content for Co does not significantly affect the corrosion resistance of the present Co-based BMGs. The test of shows that Fe and Co ions are major metal ions released into the two simulated body solutions. In Hank’s solution, the concentration of Co ion released reduces with the increase of Fe content, but the situation is the opposite in saliva solution. The result of the ions concentration released is consistent with that of the corrosion resistance test. Biocompatibility test results shows, with the increase of Fe content, Osteoblast cell viability in a leaching solution produced from the present Co-based BMGs increases, indicating that the biological toxicity to osteoblasts reduces and the biocompatibility improves.