基于TPMS结构的多孔钛制备与表征

Fabrication and Characterization of Porous Titanium Based on TPMS Structure

多孔钛因具有与人体骨组织相近的弹性模量和允许骨长入的孔隙结构而备受关注。其孔隙结构特征不仅影响骨长入效果,而且决定了多孔钛的力学性能。通过三周期极小曲面(triply periodic minimal surfaces,TPMS)隐函数参数的精确调控可以构建出理想的孔隙结构模型。本实验针对TPMS模型中常用的G单元模型,研究了G单元模型隐函数参数对孔隙率、孔径、杆径等孔隙结构特征的影响规律,设计出了孔隙率约为77%,孔径分别为300(G300)、500(G500)微米的均质孔隙结构;模仿自然长骨径向梯度结构模型,构建了相应的G单元仿生梯度孔隙结构。采用选区激光熔化(SLM)增材制造技术制备了相应的多孔钛样件,利用数字显微镜和扫描电镜观测多孔钛的孔隙结构特征,发现SLM多孔钛实测孔隙率低于设计孔隙率,实测孔径小于设计值,实测杆径大于设计值。力学性能检测结果显示,G300和G500多孔钛弹性模量分别为2.04和3.12GPa,其最大抗压强度分别为63.5和103.5MPa,梯度孔隙结构多孔钛弹性模量和最大抗压强度分别为6.3 GPa和186.9 MPa。研究结果表明,G单元梯度孔隙结构多孔钛是一种理想的承重部位骨缺损修复体。

Porous titanium(Ti)has attracted much attention due to its elastic modulus similar to that of human bone tissue and the pore architectures allowing bone ingrow.The pore architectures not only have influence on the effect of bone ingrowth but also determine the mechanical properties of porous Ti.An ideal pore architecture can be constructed by precise regulating of implicit function parameters of triply periodic minimal surface(TPMS).The Gyroid(G)cell structure was used in this paper.The influences of implicit function parameters of G cell on pore structure characteristics,such as porosity,pore diameter and strut diameter were investigated.The homogeneous pore structures with porosity of about 77%and pore size of 300(G300)and 500μm(G500)were designed.Mimicking the radial gradient structure of natural long bone,the graded G pore structure was constructed.Selective laser melting(SLM)technique was used to fabricate the porous Ti samples.Digital microscope and scanning electron microscopy(SEM)were used to observe the pore architecture characteristics of the SLM-produced porous Ti.It is found that the measured porosities of SLM-produced Ti samples are lower than the designed values.The measured pore sizes are less than the designed values and the measured strut diameters are larger than the designed values.The compression tests were examined.The results show that the elastic modulus of porous titanium of G300 and G500 is 2.04 GPa and 3.12 GPa,respectively,and its maximum compressive strength is 63.5 MPa and 103.5 MPa,respectively.The elastic modulus and maximum compressive strength of porous titanium of gradient pore structure is 6.3 GPa and 186.9 MPa,respectively.These results indicate that the G cell gradient porous Ti is an ideal alternative candidate for bone defect repair in load-bearing sites.