Li Jinbao, Ren Huijiao, Liu Changsheng, Shang Shuo
School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
Key Laboratory for Laser Application Technology of Liaoning Province, Northeastern University, Shenyang 110819, China.
Materials (Basel). 2019 Apr 23;12(8):1321. doi: 10.3390/ma12081321.
With the development of modern medical implants, there are significantly increasing demands for personalized prosthesis. Corrosion-resistance and dense cobalt alloy specimens have been successfully fabricated by laser metal deposition. The relationship between specific energy density, microstructure and corrosion resistance of the specimens is investigated. The results show that higher specific energy density promotes the formation of columnar grain and leads to coarse grain size. The evolution and distribution of deposited microstructure from bottom to top are summarized in a metallographic sketch. The corrosion current of deposited specimens increases from 2.071 × 10 A/cm to 6.86 × 10 A/cm and rapidly drops to 9.88 × 10 A/cm with increase of specific energy density from 318.8 J/g to 2752.3 J/g. The columnar and equiaxed structure of deposited specimens have lower corrosion current than mixed structure due to finer grain and less Mo segregation. The deposited have low level metal released because of passive film. The passive film have different formation routes in Hank's solution and acidic saliva. The specific energy density has an important effect on the microstructure of deposited, which improves corrosion resistance and life span in implant.
随着现代医用植入物的发展，对个性化假体的需求显著增加。通过激光金属沉积已成功制造出耐腐蚀且致密的钴合金试样。研究了试样的比能量密度、微观结构与耐腐蚀性之间的关系。结果表明，较高的比能量密度促进柱状晶的形成并导致晶粒尺寸粗大。通过金相示意图总结了从底部到顶部沉积微观结构的演变和分布。随着比能量密度从318.8 J/g增加到2752.3 J/g，沉积试样的腐蚀电流从2.071×10 A/cm增加到6.86×10 A/cm，然后迅速降至9.88×10 A/cm。由于晶粒更细且钼偏析较少，沉积试样的柱状和等轴结构比混合结构具有更低的腐蚀电流。由于钝化膜的存在，沉积物释放的金属水平较低。钝化膜在汉克溶液和酸性唾液中有不同的形成途径。比能量密度对沉积物的微观结构有重要影响，这提高了植入物的耐腐蚀性和寿命。
