The memoir of a silver-aged researcher has been introduced with the aims of assisting and enhancing the enlightenment of the research creativities of young scientists and engineers. It is stressed that research creativity absolutely depends on the human character and the sincere attitude of the research leader. To meet the excellent books as well as the respectable leader, especially in young ages, is also the most important factors for cultivating creativity. Further, it is essential to ensure the freedom and heretical behaviors in research activities, and good rivals are necessitated to cultivate the research creativity each other.

Mn-modified hexagonal YbFeO₃ (Mn-YFO) synthesized by a solvothemal method is found to have a higher catalytic activity for C₃H₈ or CO oxidation than noble metal catalyst, Pd/Al₂O₃. The catalytic activity is mainly due to amorphous MnO_x species located on ab plane of the hexagonal lattice. A small amount of Pd loading on Mn-YFO drastically enhances the catalytic activity; that is, 0.5 wt% Pd/Mn-YFO shows excellent activity for CO oxidation that exceeds the activity of 2.0 wt% Pd/Al₂O₃. The Pd loading dramatically improves the reducibility of the MnO_x species and also CO adsorption to Mn-YFO. Thus, we demonstrate that an extremely small amount of Pd species plays a role as a promoter for the catalytic and reduction functions of the MnO_x species on Mn-YFO. It is expected that the establishment of such promoter effect will provide a novel guideline for reducing the use of precious metal resources.

In this study, microstructural and mechanical properties of the extruded and heat-treated TiNi alloys by sintering the mixture of TiNi pre-mixed powder with titanium dioxide (TiO₂) particles were investigated. Pure Ti and pure Ni powder with TiO₂ particles were mixed and consolidated by spark plasma sintering (SPS). SPSed TiNi alloy compacts were extruded and heat-treated subsequently. SPSed TiNi alloy compacts had TiNi matrix and Ti₄Ni₂O phase. Ti₄Ni₂O phase was formed during SPS by reaction between TiNi matrix and oxygen atoms originated from additive TiO₂ particles. Consequently, the heat-treated Ti-50.5 at.%Ni alloy using pre-mixed powder with 1.0 vol.% TiO₂ particles showed a high plateau stress of 630 MPa and a good shape recovery of 79.7% in 8% strain applied. The heat-treated TiNi alloy with 1.0 vol.% TiO₂ particles revealed the high strength and good shape memory properties. The high strengthening mechanism of the TiNi alloy using pre-mixed powder with TiO₂ particles was mainly due to a decrease martensitic transformation temperature by an increase soluted Ni content in TiNi matrix after reaction between TiNi and TiO₂.

Aqueous reconstruction process (dissolution and reprecipitation) has been investigated at room temperature for Mg-Al LDH (layered double hydroxides: LDH). Especially, the effect of addition of Ni acetate solution on the microstructure of LDH was in detail examined through the reconstruction process for Mg-Al LDH calcined at 500°C. As a result, the layer spacing and adsorption amount of cation depended on reaction time and reaction solution. Furthermore, the substitution of Ni²⁺ for Mg²⁺ in LDH was carried out and the Ni content increased with the time of reconstruction process. Based on these results, it was found that the reconstruction process can be applicable to the synthesis of various dication-substituted LDHs.

Ashes and harmful gasses from volcanoes lead to the air pollution and severe problems for health damage and agriculture. In special, volcanoes more than 50 in Japan are volcanically active and often product a large amount of volcanic ashes. The recycle for waste of volcanic ashes pose a severe problem to the lives of residents near the volcano. The volcanic ashes are composed mostly of SiO₂. In this study the syntheses of zeolite from the waste of volcanic ash including SiO₂ were attempted through the hydrothermal solution process. The relation between the process of hydrothermal solution process and microstructure of obtained zeolites was investigated and also ion exchange ability against Sr ion was evaluated.

New composite ceramic materials enable to improve mechanical properties and various performances more than monolithic ceramic materials. Generally, composite ceramic materials include more than two different materials, in addition, more than two crystal structures in case of α and β crystal phase composite Si₃N₄ material in this research. Composite ceramic materials enable to get various different characteristics that show excellent properties, not only mechanical properties but electrical properties, resistance to oxidation and wear. Properties improvement develops many new applications with superior performance more than conventional materials. In this research, we have developed various ceramic reinforced composite, based on Al₂O₃ and ZrO₂ ceramics with carbide and nitride particles or whisker addition. Farther more we have developed α and β crystal phase composite Si₃N₄ material by researching the sintering additives stoichiometric ratio and sintering condition. Finally we succeeded in applying ceramic composite materials to various industrial parts, for example, Al₂O₃-TiC thin magnetic slider substrate, Al₂O₃-SiC whisker based cutting tool, Si₃N₄ squeezing roll and wear parts, ZrO₂-WC ceramics punch and die for high speed pressing.

WC-Ni₃Al hard metal of the composition for WC-25 vol% (Ni-24 at%Al-0.5 at%B) was prepared by vacuum sintering. The powder mixtures of WC, Ni, NiAl (Ni-50 at%Al) and B were treated by wet milling with tumbling ball mill machine for 24 hr and 48 hr. The average particle size of the powder mixtures after wet-milling for 24 hr and 48 hr were 1.69 μm and 1.23 μm, respectively. These powder mixtures were press-molded into the test-piece and sintered in vacuum of (7~9) × 10⁻³ Pa at various temperature for 1 hr. The densities, microstructures and mechanical properties of the obtained sintered compacts were investigated. When 48 hr wet-milled powder was used and the green compact was sintered at 1425°C for 1 hr, the compact had a relative density more than 99%, transverse rapture strength of 2.2 GPa and vickers hardness of 1330 HV. On the other hand, using 24 hr wet-milled powder, the sintered compact had lower mechanical properties than the compact of 48 hr wet-milled powder due to low density and inhomogeneous microstructure.

Thermal cracking is one mechanism whereby tool degradation occurs. The establishment of an evaluation method for thermal cracking is important in order to develop tool materials with high performance. The thermal shock of tool materials was investigated by repetitive laser irradiation, in particular for Ti(C,N)-based cermets. It was found that the deformation of cermets increased with increasing irradiation power. The present results confirmed that repetitive laser irradiation is effective for assessing the damage behavior of tool materials.