The compression behaviors of titanium/carbamide powder mixtures in the preparation of biomedical titanium scaffolds with the space holder method

• Compression behaviors of titanium/carbamide powder mixtures were investigated.
• Critical pressures for deformation of carbamide space holder were also determined.
• The mixture showed intermediate compression behaviors of the component powders.
• Yield pressure decreased with increasing volume fraction of carbamide.
• The rule of mixtures was applicable to estimate appropriate compacting pressures.

Titanium has been widely used as a preferred metallic biomaterial for bone tissue engineering scaffolds. So far, a number of techniques have been developed to produce porous-structured titanium, including the space holder method. However, a number of technological challenges are still present, such as the difficulties in controlling the geometry changes of space-holding particles during the compaction of titanium/space holder powder mixtures. In this research, a series of experiments were performed to investigate the compression behaviors of titanium/carbamide powder mixtures and determine maximum compacting pressures, considering the specific net energy expended during the process, the at-pressure relative density of powder compacts and the yield pressure derived from the load–displacement plots of powder compression cycles. The results showed that the titanium and carbamide powders exhibited dissimilar compression behaviors and titanium/carbamide powder mixtures exhibited intermediate compression behaviors of the monolithic titanium and carbamide powders. The yield pressures of titanium/carbamide powder mixtures, obtained from the Heckel plots and used as a measure for the appropriate compacting pressures, decreased with increasing volume fraction of carbamide in the mixture. The rule of mixtures was found to be applicable to predict the compression behaviors and the appropriate compacting pressures of titanium/carbamide powder mixtures. However, limitations of this model were recognized in the case of compacting mixtures with large volume fractions of carbamide space-holding particles (x > 50%) and at high pressures (P > 300 MPa).

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