State Key Laboratory for Turbulence and Complex System and Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, No 5 Yi-He-Yuan Road, Hai-Dian District, Beijing 100871, China.
Acta Biomater. 2010 May;6(5):1783-91. doi: 10.1016/j.actbio.2009.10.009. Epub 2009 Oct 6.
Mg/Ca (1 wt.%, 5 wt.%, 10 wt.% Ca) composites were prepared from pure magnesium and calcium powders using the powder metallurgy method, aiming to enlarge the addition of Ca content without the formation of Mg(2)Ca. The microstructures, mechanical properties and cytotoxicities of Mg/Ca composite samples were investigated. The corrosion of Mg/Ca composites in Dulbecco's modified Eagle's medium (DMEM) for various immersion intervals was studied by electrochemical impedance spectroscopy measurements and environmental scanning electron microscope, with the concentrations of released Mg and Ca ions in DMEM for various immersion time intervals being measured. It was shown that the main constitutional phases were Mg and Ca, which were uniformly distributed in the Mg matrix. The ultimate tensile strength (UTS) and elongation of experimental composites decreased with increasing Ca content, and the UTS of Mg/1Ca composite was comparable with that of as-extruded Mg-1Ca alloy. The corrosion potential increased with increasing Ca content, whereas the current density and the impedance decreased. It was found that the protective surface film formed quickly at the initial immersion stage. With increasing immersion time, the surface film became compact, and the corrosion rate of Mg/Ca composites slowed down. The surface film consisted mainly of CaCO(3), MgCO(3)x3H(2)O, HA and Mg(OH)(2) after 72 h immersion in DMEM. Mg/1Ca and Mg/5Ca composite extracts had no significant toxicity (p>0.05) to L-929 cells, whereas Mg/10Ca composite extract induced approximately 40% reduced cell viability.
采用粉末冶金法，由纯镁和钙粉制备了 Mg/Ca（1wt%、5wt%、10wt%Ca）复合材料，目的是在不形成 Mg2Ca 的情况下增大 Ca 的添加量。研究了 Mg/Ca 复合材料的微观结构、力学性能和细胞毒性。通过电化学阻抗谱测量和环境扫描电子显微镜研究了 Mg/Ca 复合材料在 Dulbecco 改良 Eagle 培养基（DMEM）中不同浸泡间隔的腐蚀情况，并测量了 DMEM 中不同浸泡时间间隔释放的 Mg 和 Ca 离子的浓度。结果表明，主要的组成相是 Mg 和 Ca，它们均匀分布在 Mg 基体中。随着 Ca 含量的增加，实验复合材料的拉伸强度和伸长率降低，Mg/1Ca 复合材料的拉伸强度与挤压态 Mg-1Ca 合金相当。随着 Ca 含量的增加，腐蚀电位升高，而电流密度和阻抗降低。研究发现，在初始浸泡阶段迅速形成了保护性表面膜。随着浸泡时间的增加，表面膜变得更加致密，Mg/Ca 复合材料的腐蚀速度减慢。在 DMEM 中浸泡 72 h 后，表面膜主要由 CaCO3、MgCO3x3H2O、HA 和 Mg(OH)2 组成。Mg/1Ca 和 Mg/5Ca 复合材料浸提液对 L-929 细胞无明显毒性（p>0.05），而 Mg/10Ca 复合材料浸提液诱导细胞活力降低约 40%。
