生物医用多孔Ti-Nb-Sn合金激光近终形成形研究

Titanium alloys are widely applied to biomaterials for repairing and substituting hard tissues in recent years due to their low density, high specific strength, excellent corrosion resistance and biocompatibility. However, the elastic modulus of bulk titanium alloys is much higher than that of natural bones, which causes stress shielding, bone degradation, loss and absorption, and accordingly implant loosening and fracture ultimately. Additionally, it is difficult to process the biomedical implant that possesses complex structure and personalized dimension by the traditional manufacturing method. Based on the aim of this project to develop laser near-net-shape forming of porous Ti-Nb-Sn alloys by combining selective laser sintering with homogenization treatment, the influences of alloy powder characteristics and laser processing parameters on the accuracy and strength of formed porous alloys is studied, and the forming mechanism of selective laser sintering of porous alloys is explored accordingly. Under consideration of the pore structure and microstructure of porous Ti-Nb-Sn alloys, the mechanical properties are investigated to make clear the deformation behavior and failure mechanism, and to establish the functional relation between the mechanical performance and pore feature; the electrochemical behavior is carried out to clarify the corrosion mechanism in simulated physiological environment; and the mechanism of apatite formation on the porous alloys soaked in simulated body fluid is also investigated to predict their bioactivity. The research results have great significance that it will accelerate the biomedical applications of porous Ti-Nb-Sn alloys, and satisfy the demands of lots of patients.

钛合金具有低密度、高比强度、良好的耐蚀性能和生物相容性，近年来被广泛用于硬组织修复和替换材料。但是，块体钛合金因弹性模量远高于自然骨而引起应力屏蔽，造成骨退化、萎缩、甚至被吸收，最终导致植入体松动和断裂。另外，医用植入体的结构形状复杂，尺寸因人而异，传统制造方法很难加工。本项目以开发多孔Ti-Nb-Sn合金选择性激光烧结―均匀化处理的近终形成形技术为目标，研究合金粉末特性和激光工艺参数对多孔合金成形精度和强度的影响规律，探索选择性激光烧结多孔钛合金的成形机理；基于研究孔隙结构和微观组织，分析多孔钛合金受力时的变形行为及破坏机理，建立以孔隙特征为参数的力学性能函数；研究多孔钛合金在模拟生理环境中的电化学行为，探索其腐蚀机理；研究其在仿生溶液中表面生成磷灰石的机理，预测其生物活性。该研究成果对促进多孔Ti-Nb-Sn合金在生物医学领域的应用，满足广大患者对生物材料的需求，具有重大的现实意义。

钛及钛合金因具有高比强度、低弹性模量、优异的抗腐蚀性和生物相容性等特点，在骨植入和牙修复领域得到了广泛应用。选择性激光烧结技术能够个性化设计、并快速制造具有任意复杂外形的定制植入体。本项目以金属元素粉末Ti、Mo与粘结剂的混合粉末为原料，采用间接选择性激光烧结工艺，制备了多孔Ti-Mo（Mo=4, 6和7.5wt.%）合金，研究了其孔隙结构、显微组织、力学性能和腐蚀行为。结果表明，多孔Ti-Mo合金的结构、力学和电化学性能随孔隙特征变化且能够调整与自然骨匹配。多孔Ti-Mo合金因其独特的孔隙结构，适宜的力学性能和良好的耐蚀性能，将是很有吸引力的生物材料。