PREPARATION OF BIOACTIVE NANOSTRUCTURE SCAFFOLD WITH IMPROVED COMPRESSIVE STRENGTH

Highly porous scaffolds with open structure are today the best candidates for bone substitution to ensure bone oxygenation and angiogenesis. In this study, we developed a new route to enhance the compressive strength of porous hydroxyapatite scaffold made of natural bone. Briefly, the spongy bone of an adult bovine was extracted, annealed, and coated by a nanostructure bioactive glass layer to be subsequently sintered at different temperatures. The apatite formation ability on the surfaces of the coated scaffolds was investigated by standard procedures. Our results showed that the scaffold and coating microstructure consisted of the grains smaller than 100 nm. These nanostructures improved the compressive strength and bioactivity of highly porous scaffold. The results showed that with increasing the sintering temperature, the compressive strength of scaffolds increased while their in vitro bioactivity decreased

Enhanced Mechanical Properties and Microstructure of Accumulative Roll-Bonded Co/Pb Nanocomposite.

Lead composites have been used as anode in electrowinning process to produce metals such as copper and zinc. Manufacturing of stable lead anodes with appropriate mechanical and chemical properties is required to improve the performance of the electrowinning processes. In this study, accumulative roll bonding (ARB) method was used to fabricate Co/Pb nanocomposite. Utilizing ARB method can help us to achieve a uniform structure with enhanced mechanical properties via sever plastic deformation. The results showed that suitable tensile properties were obtained in Pb-%0.5Co-10pass samples. The tensile strength and strain of these samples were 2.51 times higher and 83.7% lower than that of as-cast pure Pb. They also showed creep resistance and hardness up to 1.8 and 2.5 times more than that of as-cast pure Pb. ARB technique uniformly distributed Co par-ticles in the Pb matrix. The enhanced strength of Pb samples was observed in the composite in-cluding grain size less than 50 nm as a result of hindering the recovery phenomenon. The particle size of the Co distributed in the Pb matrix was 353 ± 259 nm. Compared to conventional methods, ARB process improved the mechanical properties of Co/Pb composites and can open a new horizon to fabricate this composite in metal industries