STUDIES ON SELECTIVE LASER MELTING FORMING AND PROPERTIES OF TI POROUS STRUCTURES
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实验表明，通过合适的选区激光熔化工艺参数可以顺利成型介观尺度的多孔结构，且最优能量密度约为实体结构的0.4倍，通过调节不同能量密度，还可形成不同的微表面粗糙结构；氮气氛强化纯Ti多孔结构的性能可以通过其与孔隙率及单胞尺寸等参数的关系进行较好预测；Ti多孔结构的生物相容性及促进细胞融合生长性能优良，其中 螺旋十二面体型多孔结构样品综合性能最优；各种多孔结构弹性模量均在0.2~20 GPa范围内，符合人体骨质的模量范围，因此能很好减缓应力屏蔽效应，适合植入物应用。
3D printing technology, also known as additive manufacturing, is a manufacturing method of adding materials layer by layer through automatic control based on 3D model data to finally produce the required parts, which makes 3D printing less limited by complex geometries. Therefore, the application of 3D printing technology in the field of orthopedic implants has been rapidly developed. 3D printing technology can prepare orthopedic implants with complex porous structures and internal structures. However, under the premise of the same biocompatible materials, different types of porous structures in 3D printed orthopedic implants, the same porous structure in the case of different geometric structure parameters, its influence on the growth of biological osteoblasts has not been systematically studied. The existing technical process, only relies on the experience of doctors and designers for selection, which reduces the reliability and scientificity of implants to a certain extent. In this study, five porous structures such as Dodecahedron, Diamond, Gyroid, Fischer Koch S and Voronoi were selected, 3D modeling by computer-aided design technology and 20 samples with different structural parameters were prepared by selective laser melting under N2 and Ar mixture atmosphere.
In this study, compression tests were carried out on samples with different porous structures, and the influence of porosity and unit cell length on the elastic modulus was analyzed. At the same time, key mechanical properties such as yield strength, ultimate strength, and energy absorption capacity were measured. The corresponding parameters of the bone were compared to characterize the difference in mechanical properties; the samples were subjected to osteoblast culture experiments and mineralization, and the Ca content was semi-quantitatively analyzed by a microplate reader, and the osteoblasts in different porous structures were compared. Growth in the sample through live and dead cell staining, the growth of cells in the porous structure and the ability to attach to the surface were studied to study the difference in the growth of cells in different porous structures. Finally, the samples were tested for cell proliferation and toxicity and hemolytic test to more comprehensively verify its biological properties.
The research shows that the mesoscopic-scale porous structure can be successfully formed by suitable selective laser melting process parameters, and the optimal energy density is about 0.4 times that of the solid structure. Different micro-surface rough structures can also be formed by adjusting different energy densities. The performance of pure Ti porous structure strengthened by nitrogen atmosphere can be well predicted by its relationship with parameters such as porosity and unit cell size. Among them, the Gyroid porous structure sample has the best comprehensive performance. The elastic modulus of various porous structures is in the range of 0.2~20 GPa, which is in line with the modulus range of human bone, so it can well reduce the stress shielding effect and is suitable for implant applications.
|Year of Degree Awarded|
 Suresh G , Reddy M H , Narendra G , et al. Summarization of 3D Printing Technology in Processing & Dovelopment of Medical Implants[J]. J.Mech.Cont.& Math. Sci,2019,14(1):176-191.
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|Department||School of Innovation and Entrepreneurship|
刘永伦. Ti多孔结构选区激光熔化成型及性能研究[D]. 深圳. 南方科技大学,2022.
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