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

详细研究了非平衡态Cu-Zr、Cu-Ta和Ni-Zr合金的氧化行为以及Co-Zr合金对NO直接分解的催化性能。快速淬火Cu-Zr合金表面形成的初始表面ZrO_2膜很薄，具有保护作用，但由于与大气中的水分反应，失去了保护作用，导致合金氧化。与水分反应形成金属铜层和ZrO_2层的夹层结构。形成了两种类型的ZrO_2氧化物：四方相和单斜相；前者通过与大气水分的反应转化为后者。采用溅射沉积法制备的Cu-Ta合金，在相对湿度为70%的空气中，在70℃下暴露60小时，使其呈现出不同的颜色。颜色取决于合金成分。有色试样的最表面由金属铜组成，铜的氧化层下含有Ta，其着色主要取决于初始氧化膜的保护作用。一种厚度约为20mum的Ni-33Zr合金在高温下表现出Zr在空气中的完全优先氧化。镍在Zr完全氧化后被氧化。在高镍合金上形成的ZrO_2主要是四方晶型，在低镍合金上形成单斜晶型。在HF溶液中对含有少量pt族元素的非晶态Co-Zr合金进行氧化处理，形成了分散在氧化物上的pt族金属微粒，对NO的分解反应表现出较高的活性。另一方面，二元Co-Zr合金对上述反应没有催化活性。在添加的pt族金属中，钯是最有效的，由于Co_3O_4、ZrO_2和金属钯的协同作用，Co-Zr-Pd合金的催化活性几乎与Pd-black一样高。成功制备了纳米尺寸的Fe-Cr-P-C非晶合金粉末。

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.