Investigation of spacer size effect on architecture and mechanical properties of porous titanium

Titanium and its alloy foams have been receiving a growing interest for biomedical industry due to their biocompatibility and high potential in dental, spinal, joint and hip implant applications. Near net shape production and reproducibility of a product require a full understanding of the processing parameters' effect on manufacturing and final properties. The shape complexity of titanium surgical implants, for example dental implants, necessitates a good control in compaction and sintering of metal skeletons containing macropores for near-net shape manufacturing. In this study, effects of processing parameters such as spacer powder size and amount on compaction, sintering and final structural properties were investigated. Commercially pure cellular titanium with porosities ranging between 35 and 75% and pore sizes between 100 mu m and a few millimeters were produced via powder metallurgy with spacers. Architectural parameters of the foams, before and after sintering, were quantitatively characterized via X-ray computed microtomography. Addition of fine spacer powders enhanced compaction and densification of the foam structure. Pore walls were observed to get thicker during sintering. The use of coarser space holders resulted in thicker pore walls and a wider pore wall thickness distribution. The results indicated that strength and stiffness tend to increase with increasing pore size. Among the structural features that spacer size altered, pore wall thickness and pore face roughness were found to be the most dominant effects on strength and stiffness. (C) 2011 Elsevier B.V. All rights reserved.