Fu Qiang, Rahaman Mohamed N, Dogan Fatih, Bal B Sonny
Department of Materials Science and Engineering, University of Missouri-Rolla, Rolla, Missouri 65409, USA.
J Biomed Mater Res B Appl Biomater. 2008 Aug;86(2):514-22. doi: 10.1002/jbm.b.31051.
In Part I, the influence of processing parameters on the general microstructure of freeze-cast hydroxyapatite (HA) constructs was explored. This work is an extension of Part I to investigate the effect of sintering conditions on the microstructure and mechanical behavior of freeze-cast HA. For constructs prepared from aqueous suspensions (5-20 vol % HA), sintering for 3 h at temperatures from 1250 degrees C to 1375 degrees C produced a decrease in porosity of <5% but an increase in strength of nearly 50%. Constructs with a porosity of 52% had compressive strengths of 12 +/- 1 MPa and 5 +/- 1 MPa in the directions parallel and perpendicular to the freezing direction, respectively. The mechanical response showed high strain tolerance (5-10% at the maximum stress), high strain to failure (>20%), and high strain rate sensitivity. Manipulation of the freeze-cast microstructure, achieved by additions of glycerol and 1,4-dioxane to the aqueous suspensions, produced changes in the magnitude of the mechanical response, but little change in the general nature of the response. The favorable mechanical behavior of the porous constructs, coupled with the ability to modify their microstructure, indicates the potential of the present freeze-casting route for the production of porous scaffolds for bone tissue engineering.
在第一部分中，探讨了加工参数对冷冻铸造羟基磷灰石（HA）结构总体微观结构的影响。本文是第一部分的扩展，旨在研究烧结条件对冷冻铸造HA微观结构和力学行为的影响。对于由水悬浮液（5 - 20体积% HA）制备的结构，在1250℃至1375℃的温度下烧结3小时，孔隙率降低了<5%，但强度提高了近50%。孔隙率为52%的结构在平行和垂直于冷冻方向上的抗压强度分别为12±1 MPa和5±1 MPa。力学响应表现出高应变耐受性（最大应力下为5 - 10%）、高破坏应变（>20%）和高应变率敏感性。通过向水悬浮液中添加甘油和1,4 - 二氧六环来控制冷冻铸造微观结构，会使力学响应的大小发生变化，但响应的总体性质变化不大。多孔结构良好的力学行为，以及改变其微观结构的能力，表明当前冷冻铸造方法在生产骨组织工程多孔支架方面具有潜力。
