Abstract
Highly porous Ti matrix composites can be a solution for some of the major clinical concerns for the load bearing implants such as low tribocorrosion resistance, stress shielding, and lack of biological anchorage. In order to respond to these needs, highly porous Ti-TiB-TiNx in-situ composites were synthesized by pressureless sintering using BN as reactant and urea as space holder. Corrosion behaviour was investigated at body temperature, in phosphate buffer saline solution (PBS), by measuring open circuit potential (OCP) and cyclic polarization. Wear behaviour was studied in PBS by reciprocating against a 10 mm diameter alumina ball under 3 N of normal load and 1 Hz of frequency. Results showed that the formation of the in-situ reinforcing phases led to an increase on the hardness and on the wear resistance, as well, neither macro porosity nor the reinforcing phases led to localized corrosion.
Highlights
Metallic biomaterials are still indispensable since at least approximately 70% of biomedical implants are produced from them [1,2,3]
Starting from angular shaped Ti, BN, and urea powders (Figures 1a–1c), highly porous Ti and Ti-TiB-TiN x in situ composites having 30% of nominal porosity were produced (Figures 1d–1f)
Detailed microstructural analysis of the dense Ti-TiB-TiN x in situ composite synthesised by using the same Ti:BN weight ratio at the same temperature had previously been reported elsewhere [27] where Ti, TiB whiskers, and substoichiometric TiN x phases where identified on the structure based on SEM/EDS and XRD analyses, and the formation mechanism of each in situ reinforcing phase were discussed
Summary
Metallic biomaterials are still indispensable since at least approximately 70% of biomedical implants are produced from them [1,2,3]. Tang et al [24] produced Ti6Al4V matrix, in situ formed TiC reinforced composites having approximately 25% of porosity by microwave sintering using multiwalled carbon nanotubes as reactant ( acted as a microwave susceptor) and reported increased hardness and compressive strength for the composites. The author and his coworkers had previously synthesized dense Ti-TiB-TiN x in situ hybrid composites by reactive hot pressing and reported significantly improved dry sliding wear [27] and tribocorrosion [28] behaviour for the composites. Ti-TiB-TiN x in situ hybrid composites were produced with 30% nominal porosity (i.e. space holder volume fraction) by P/M with space holder technique, and their corrosion and wear behaviour were studied in a physiological solution
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