טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentOlga Shalev
SubjectProcessing and Characterization of Porous Metal-based
Structures Designed as Scaffolds for Bone
Ingrowth
DepartmentDepartment of Materials Science and Engineering
Supervisors Full Professor Gutmanas Elazar
Dr. Gotman Irena


Abstract

Development of high-strength synthetic implants for filling osseous defects in long bones is one of many challenges of biomedical materials engineering. Besides mechanical strength, the main requirements of such bone graft substitutes are biocompatibility, low stiffness closely matching that of bone and osteoconductivity which is achieved by using porous implants having interconnected porosity in the range of 100-500 micrometers. The main objective of the present work was the fabrication of strong structures with high interconnected porosity and regular pore shape and size designed to function as scaffolds for bone ingrowth.

Carbon foams with pore size ranging from 250 to 500 micrometers were converted by using an original PIRAC method: samples were immersed into various metal powders (Ti, Nb, Cr), admixed with iodine and heat-treated. Reactive diffusion of a metal into carbon yielded the corresponding metal-based porous structure whose geometry was dictated by the strut thickness and pore size of the carbon foam.

When carbon foams were treated in Ti/ Nb, mechanically-weak structures with corresponding metal carbides layers of several microns thickness were obtained. At the same time, PIRAC treatments in Cr powder resulted in much stronger structures, as carbon foam was fully converted into porous chromium carbide structure. In order to obtain a biocompatible metallic surface, porous carbon samples were first treated in chromium and then in titanium or niobium. The layers of an almost pure metallic Ti or Nb formed on the surface of porous PIRAC-converted Cr carbide structures should provide these scaffolds with the required biocompatibility and bone conducting capability.