Additive Layered Manufacturing of Reticulated Ti-6A1-4V Biomedical Mesh Structures by Electron Beam Melting

摘要

Porous coatings, notably thin, porous bead coatings, sintered mesh arrays, thermal-spray coatings and metallic foams have been incorporated into biomedical devices and appliances for several decades to improve bone compatibility, stability, and bone ingrowth. In this research program, we are concerned with the fabrication of reticulated mesh arrays as integral components of monolithic products using Ti-6A1-4V powder to build complex, 3D structures by electron beam melting (EBM). Utilizing software capable of building lattice-truss or cellular lattices with high symmetry, 3D-periodic reticulated arrangements such as hip stem and knee component prototypes have been fabricated with complete mesh arrays or with solid stems with a surrounding mesh structure completely fabricated as a monolithic product. The 3D mesh structures begin with so-caUed lattice elements which can be designed, computed, and attached to a CAD program for additive layered manufacturing by EBM. Mesh arrays with cortical bone density (1.9 g/cm~3) can be fabricated with various lattice-truss structures and truss dimensions tailored to stress-strain and stiffness properties to optimize porous bone-replacement implants, including craniofacial replacements, etc. Mesh-to-mesh structures and functionally graded structures are also explored. Metallographic analysis of these structures using optical and electron microscopies illustrate their microstruc-tural characteristics in association with measured mechanical properties such as microindentation hardness which can be related linearly to residual stress.