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PRIMARY STUDY OF CREATION OF FINE METALLIC PARTICLES DISPERSED ON METAL OXIDES BY UTILIZING PROPERTIES OF NON-EQUILIBRIUM ALLOYS

利用非平衡合金的性质制造分散在金属氧化物上的细小金属颗粒的初步研究

基本信息

批准号：
06402051
负责人：
ASAMI Katsuhiro
金额：
$ 17.6万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

Oxidation behavior of non-equilibrium Cu-Zr, Cu-Ta and Ni-Zr alloys and catalytic properties of Co-Zr alloys for NO direct decomposition were examined in details.The initial surface ZrO_2 film formed on the rapidly quenched Cu-Zr alloy surface was very thin and protective, but it lost its protectiveness by reaction with moisture in atmosphere, resulting in oxidation of the alloy. The reaction with moisture developed a sandwich-structure of metallic copper layrs and ZrO_2 layrs. Two types of ZrO_2 oxide, tetragonal and monoclinic phases were formed ; the former transformes to the latter phase by reaction with the atmospheric moisture.Cu-Ta alloys prepared by sputter-deposition were colored to various colors by exposure to an air with relative humidities of 70% at 70ﾟC for 60 hours. The color depends on the alloy composition. The topmost surface of the colored specimens consisted of metallic copper, under which oxide layr containing Ta, and the coloration depends mostly on the protectiveness of the initial oxide film.A morphous Ni-33Zr alloy about 20mum thick showed complete preferential oxidation of Zr in air at high temperature. Nickel was oxidized after the complete Zr oxidation. The formed ZrO_2 was mainly tetragonal on high Ni alloys and monoclinic on low Ni alloys.Treatment of amorphous Co-Zr alloys containing small amount of Pt-group elements in HF solutions followed by oxidation formed fine particles of Pt-group metals dispersed and supported on oxides and showed high activity to the decomposition reaction of NO.On the other hand, binary Co-Zr alloys had no catalytic activity to the above reaction. Among the additive Pt-group metals, palladium was most effective, and Co-Zr-Pd alloys had almost the same high catalytic activity with that of Pd-black because of synergistic action of Co_3O_4, ZrO_2 and metallic Pd for the catalytic reaction.Amorphous Fe-Cr-P-C alloy powder of nanometer-size was also successfully formed.

详细研究了非平衡Cu-Zr、Cu-Ta和Ni-Zr合金的氧化行为和Co-Zr合金对NO直接分解的催化性能。在快速淬火的Cu-Zr合金表面形成的初始表面氧化膜非常薄且具有保护性，但与大气中的水分反应使其失去保护性，导致合金氧化。与水分的反应形成了金属铜层和氧化锆层的夹心结构。在70ﾟC、相对湿度为70%的空气中反应60h，溅射沉积的CuTa合金被着色成不同的颜色。颜色取决于合金成分。着色试件的顶层为金属铜，其下面是含Ta的氧化层，着色主要取决于初始氧化膜的保护作用。20微米厚的形态Ni-33Zr合金在高温下表现出在空气中对Zr的完全优先氧化。在完全氧化后，镍被氧化。含少量铂族元素的非晶态Co-Zr合金在HF溶液中处理后再氧化，生成的铂族金属微粒分散在氧化物上，对NO的分解反应表现出较高的活性，而二元Co-Zr合金对上述反应没有催化活性。在添加的铂族金属中，钯是最有效的，由于Co3O4、ZrO2和金属Pd对催化反应的协同作用，Co-Zr-Pd合金具有与Pd-Black几乎相同的高催化活性，并成功地形成了纳米级的非晶态Fe-Cr-P-C合金粉末。