Preparation of closed-cell Mg foams using SiO2-coated CaCO3 as blowing agent in atmosphere
Preparation of closed-cell Mg foams using SiO2-coated CaCO3 as blowing agent in atmosphere
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DOI：
10.1016/s1003-6326(13)62667-9
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发表时间：
2013-06-01
影响因子：
4.5
通讯作者：
Zhang, Xing-guo
中科院分区：
文献类型：
--
作者：
Lu, Guo-qiang;Hao, Hai;Zhang, Xing-guo
在熔融发泡法中，发泡剂的热稳定性和发泡速度显著影响泡沫金属的孔结构、孔径和孔隙率。为了减缓镁泡沫的发泡速度，提高镁泡沫的热稳定性，采用Na 2 O中心点nSiO（2）和稀盐酸在CaCO 3发泡剂表面包覆SiO2钝化层。采用热重-差热分析（TGA-DTA）、X射线衍射（XRD）和扫描电子显微镜（SEM）研究了SiO2钝化层的热稳定性和微观结构。结果表明，包覆碳酸钙的热稳定性得到了提高。SiO2层为非晶网状结构。对比实验表明，包覆后的碳酸钙发泡平稳。此外，在不使用保护气体的情况下，通过合金化制备了大尺寸、均匀的阻燃泡沫镁。泡沫镁的孔隙率为60%~ 70%。
In melt foaming method, the thermal stability and foaming speed of blowing agent significantly affect the pore structure, pore size and porosity of metal foams. To retard the foaming speed and increase thermal stability, Na2O center dot nSiO(2) and dilute hydrochloric acid were used to coat SiO2 passive layer on the surface of CaCO3 which is the blowing agent of Mg foams. Thermal stability and microstructure of the SiO2 passive layer were studied by thermo gravimetric analyzer-differential thermal analysis (TGA-DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the thermal stability of coated CaCO3 is improved. The SiO2 layer is amorphous with reticular structure. Contrasting experiments reveal that the coated CaCO3 can foam placidly. Moreover, large size and homogeneous Mg foams were prepared without protective gas with the ignition-proof by alloying. And the porosity of the Mg foams is 60%-70%.