Effects of Sintering Temperature on the Porosity and Mechanical Behavior of Porous Titanium Scaffolds Prepared by Freeze
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JMEPEG https://doi.org/10.1007/s11665-019-04291-w
Effects of Sintering Temperature on the Porosity and Mechanical Behavior of Porous Titanium Scaffolds Prepared by Freeze-Casting Joe-Ming Chang, Guan-Lin Liu, and Hsiao-Ming Tung (Submitted September 10, 2018; in revised form July 2, 2019) The purpose of this study was to investigate the effects of sintering temperature on the microstructure, and associated mechanical properties of porous titanium scaffolds prepared by freeze-casting. Sintering temperature significantly influenced the porosity and the mechanical properties of the titanium scaffolds. The porosity decreased from 60 to 20% as the sintering temperatures increased from 800 to 1100 °C. The scaffolds were of an open pore structure with pore sizes ranging from 2 to 20 lm. The average wall thickness of the porous titanium was measured, using a micro-computed tomography, to be in the range from 9.2 to 26.2 lm. Elastic modulus was between 2 to 7 GPa, depending on vacuum annealing conditions. The compression strength of the scaffolds may exceed 1000 MPa as the sintering temperature higher than 1000 °C. The increase in titanium strength and stuffiness could be mainly attributed to the decrease in porosity as well as the increase in wall thickness. Keywords
freeze-casting, mechanical strength, porous titanium, sintering temperature
1. Introduction Freeze-casting is a solidification process by which the porous materials are fabricated. Powder and working fluid are added together, and by proper mixing, the chosen particles are evenly suspended in the fluid. As the temperature of fluid is decreased below the freezing point, the particles are rejected and then the wall of the solidifying fluid is formed. As a result, a pore structure is generated after removal of the solid. Through this technique, the porous structures, including size, shape, volume fraction of porosity, can be altered by changing the process parameters (Ref 1-5). For instance, the wall-to-wall distance is increased by increasing the particle size (Ref 1). The shape of the pores, structural morphology and the bridges between adjacent walls can be changed by using different additives (Ref 2). The porosity decreases with increasing the volume fraction of the particles (Ref 6). In addition to porous ceramics, porous metals were also successfully prepared by the freeze-casting technique recently (Ref 7, 8). Potential applications included supercapacitors (Ref 9), photocatalysis (Ref 10), sensors (Ref 11) and biomaterials (Ref 12, 13), revealing its versatility.
Joe-Ming Chang, Guan-Lin Liu, and Hsiao-Ming Tung, Institute of Nuclear Energy Research, Taoyuan 32546, Taiwan, ROC. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
One of the porous metals fabricated by freeze-casting is titanium, due to its low density and modulus, high strength, good biocompatibility. Therefore, it has been considered for medical implants and other technological applications (Ref 14, 15). For example, for titanium with a proper pore structure, t
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