Influence of Solid Loading on the Gel-Casting of Porous NiTi Alloys.

Porous NiTi alloys are widely applied in the field of medical implant materials due to their excellent properties. In this paper, porous NiTi alloys were prepared by non-aqueous gel-casting. The influence of solid loading on the process characteristics of slurries and the microstructure and mechanical properties of sintered samples were investigated. The viscosity and the stability of slurry significantly increased with the growth of solid loading, and the slurry had better process characteristics in the solid loading range of 40-52 vol.%. Meanwhile, the porosity and average pore diameter of the sintered NiTi alloys decreased with a rise in the solid loading, while the compressive strength increased. Porous NiTi alloys with porosities of 43.3-48.6%, average pore sizes of 53-145 µm, and compressive strengths of 87-167 MPa were fabricated by gel-casting. These properties meet the requirements of cortical bone. The results suggest that the pore structure and mechanical properties of porous NiTi products produced by gel-casting can be adjusted by controlling the solid loading.

Microstructure and Mechanical Properties of Porous NiTi Alloy Prepared by Integration of Gel-Casting and Microwave Sintering.

Porous NiTi alloys were manufactured by integration of gel-casting and microwave sintering. The effects of sintering temperature on porosity, compressive strength, pore morphology and phase composition of sintered samples were researched. The results show that the porosity and the mean pore diameter of porous NiTi alloys decrease with increasing sintering temperature, whereas the content of the NiTi phase, the elastic modulus and compressive strength of sintered samples increase. When the gel body with the solid loading of 50 vol.% is microwave sintered at 1000 °C for 30 min, porous NiTi alloys are obtained with the porosity of 38.9%, the compressive strength of 254 MPa, elastic modulus of 4 GPa, and predominant phase of NiTi. The results suggest that the method is suitable for rapid preparation of large-size and complex-shape personalized products similar to human bones at a low cost.

Study on a Novel Biodegradable and Antibacterial Fe-Based Alloy Prepared by Microwave Sintering.

This research produced a porous Fe-8 wt.% Cu alloy by microwave sintering in order to achieve (i) an increased biodegradation rate, and (ii) an antibacterial function. The Fe-8Cu alloy had higher density, hardness and degradation rate (about 2 times higher) but smaller and fewer surface pores, compared to the pure Fe. The Fe-8Cu alloy had a strong antibacterial function (the antibacterial rates against E. coli were up to 99.9%) and good biocompatibility. This work provides a novel approach of alloy design and processing to develop novel antibacterial Fe-based alloys.