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Abstract

This work focuses on basic research into a P/M processed, porous-surfaced and functionally graded material (FGM) destined for a permanent skeletal replacement implant with improved structural compatibility. Based on a perpendicular gradient in porosity the Young's modulus of the material is adapted to the elastic properties of bone in order to prevent stress shielding effects and to provide better long-term performance of the implant-bone system. Using coarse Ti particle fractions the sintering process was accelerated by silicon-assisted liquid-phase sintering (LPS) resulting in a substantial improvement of the neck geometry. A novel evaluation for the strength of the sinter contacts was proposed. The Young's modulus of uniform non-graded stacks ranged from 5 to 80 GPa as determined by ultrasound velocity measurements. Thus, the typical range for cortical bone (10-29 GPa) was covered. The magnitude of the Poisson's ratio proved to be distinctly dependent on the porosity. Specimens with porosity gradients were successfully fabricated and characterized using quantitative description of the microstructural geometry and acoustic microscopy.

Realization of a Titanium Spinal Implant with a Gradient in Porosity by 2‐Component‐Metal Injection Moulding

“…This aim might be achieved by introducing adequate porosity in the metallic structure. [7][8][9][10][11] For load-bearing implants, a combination of dense and porous parts or a gradient in porosity is often the best compromise to achieve sufficient stability and osseointegration. [12] While the dense part is responsible for the mechanical stability, the porous part of the implant promotes osseointegration.…”

Open Celled Porous Titanium

“…This will result in the initiation of small necks among the particles via diffusion and the retention of relatively small pores due to incomplete densification, provided the temperature and duration of the sintering step is appropriately controlled (sufficient to cause inter-particle bonding, but not enough to reach near full density). The process has been used for the manufacture of Ti with a total porosity of up to 60 %, showing an elastic modulus of 5-60 GPa [9] . The sintering characteristics, and hence porous structure, are affected by the size of the starting powder.…”

Fabrication, Structure, Properties and Application of Gradient Sintered Carbide-Steels with HS6-5-2 Matrix

“…In bone surgery, ceramic materials with a porosity gradient can be used for fabrication of orthopaedic gradients, which are designed just like a living bone tissue [65][66][67][68][69][70].…”