定向凝固后脱合金制备微-纳双尺度复合多孔金属

A new idea was presented in this research project proposal for fabrication of new type porous metals with orderd micrometer scale pores and random nanometer scale pores by combination of directional solidificaton process (Gasar) and dealloying process, in which, Gasar process was used for forming of the directional regular micrometer scale pores, and dealloying process was used for forming of the random nanometer scale pores separately. In order to do so, two technical routes will be taken. One is preparing lotus-type porous Cu-Mn alloy with long cylindrical pores alined in one direction by Gasar process first, and then dealloying it to obtain 3D porous Cu with double scale pores. The other is preparing lotus-type porous pure Cu by Gasar process first, and then making Cu-Zn or Cu-Mn alloy layer on the pore walls of porous Cu by vapor deposition, chemical plating, electroplating or dip plating, plus proper heat treatments, and finally dealloying it to obtain porous Cu with nanometer scale pores on the surface layer of micrometer scale pores' walls. A systematic research will be made on the theory of alloy-gas eutectic solidification, the fabrication optimizing of regular porous alloy by Gasar process, the mechanism of the forming of nanometer scale porous structure based on regular micrometer scale porous structure, the effect of dealloying etching parameters on nanometer scale pores and the detailed procedure and mechanism of dealloying etching. This kind of new type porous metals will possess various merits of porous materials, porous metals, nanoporous materials, microporous materials and regular porous materials, and has very important potential applications.

利用定向凝固工艺制备具有微米级孔的规则多孔结构(Gasar)，利用脱合金腐蚀工艺制备具有纳米级孔的无序多孔结构，把两种工艺结合形成一种制备有序-无序组合、微米孔-纳米孔复合的新型微-纳复合多孔金属的新方法。将沿两条技术路线展开研究，一是先利用Gasar工艺直接制得定向规则多孔Cu-Mn合金，然后进行脱合金腐蚀以获得三维通透的微孔-纳孔复合的双尺度多孔Cu；另一路线是利用Gasar工艺先制得定向规则多孔纯Cu，然后进行孔表面合金化沉积及热处理获得带Cu-Mn或Cu-Zn合金表层的定向多孔Cu，最后进行脱合金腐蚀获得孔壁带有纳米孔表层的双尺度多孔Cu。系统研究合金-气体共晶凝固理论及Gasar多孔合金的优化制备条件、脱合金腐蚀工艺参数对在定向微米多孔结构基体上形成纳米多孔结构的影响规律及脱合金腐蚀机理。所制得的微-纳孔复合的多孔金属将兼具规则多孔金属、纳米多孔材料的诸多优点，具有重要应用价值。

本项目研究利用定向凝固工艺制备具有微米级孔的规则多孔结构，利用脱合金腐蚀工艺制备具有纳米级孔的无序多孔结构，把两种工艺结合形成一种制备有序-无序组合、微米孔-纳米孔复合的新型微-纳复合多孔金属的新方法。.发展了定向凝固规则多孔合金制备技术。基于Cu-Mn合金系，得到了制备定向凝固规则多孔（百微米）合金的条件，进而通过脱合金使定向凝固规则多孔Cu-Mn合金的孔壁成为纳米（几十纳米）通孔结构，从而制备出了微米-纳米双尺度、直通（微米）-随机（纳米）双结构的复合多孔金属，使得制备厘米尺度块体甚至更大尺寸的纳米多孔金属产品成为可能。在纳米级高精度过滤等方面有重要应用前景。.研发了定向凝固规则多孔铜内表面制备纳米多孔层的方法。定向凝固规则多孔金属的一个重要结构特点是孔内壁光滑，但在传热等功能中，内表面毛化是更优的结构。本项目研究实现了这种毛化。同时，为金属细深孔内表面纳米多孔化提供了新的可行方法。.研发了制备大尺寸、高质量定向凝固规则多孔金属的新技术。采用Bridgman法变拉速技术，在优化的拉速下成功制备出了直径150mm、高约200mm、重约20kg的优质大尺寸Gasar Cu铸锭。制备大尺寸、高质量的Gasar Cu铸锭，是实现低成本、工业化生产Gasar Cu 产品，如Gasar Cu 热沉的基础，具有重要应用前景。