The unique set of mechanical properties found in rigid biological tissues, which combine high strength and stiffness with superior toughness, offer inspiration for the design of advanced functional structural materials with outstanding performance. This paper reports on the first utilization of one such biogenic material—siliceous sponge spicules, the skeletal elements of sponges (Poriphera)—as a unique naturally nanostructured template for vacuum deposition, while also reporting on the effects of the required chemical and thermal treatments for template preparation on the material’s microstructure and mechanical properties. The confined space within the central channel of spicules from the sponge Euplectella acts simultaneously as a nanotemplate and as a biogenic, optically transparent, glassy microchamber for the preparation of micrometer-sized clusters of fullerene-C60 through vacuum deposition onto the nanostructured surface. This biological material allows an unprecedented and unique microporous morphology of C60 particles to be obtained.

Cathode reaction on overpack corrosion in the geological repository environments of radioactive waste was identified from corrosion experiments of carbon steel specimens. Carbon steel specimens were encapsulated in degassed glass ampoules with various solutions which were prepared by distilled water degassed by Ar gas bubbling, and set in a thermostatic bath for several weeks. In the X-ray diffraction and X-ray photochemical spectroscopy, crystalline Fe3O4 and Fe2(OH)2CO3, and amorphous Fe(OH)2 were mainly detected on specimens which were immersed into distilled water, high concentration of sodium hydrogen carbonate solution, and low concentration of sodium hydrogen carbonate solution and sodium sulfate solution, respectively. Only hydrogen gas was detected in a gas phase analysis, indicating that hydrogen generation reaction was the dominant cathode reaction in the anoxic condition expected in geological repository environments.

Porous Al2O3/Al catalyst supports were fabricated using a mixture of Al(OH)3 and Al powders, followed by pressureless sintering at a temperature of 600 °C in vacuum. Different pressures were used to prepare green compacts. High compaction pressure led to a high surface area and good mechanical and electrical properties for the sintered specimens. However, when the Al content in the sintered specimen exceeded a definite value, high compaction pressure decreased the surface area abruptly. Scanning electron microscopy observations revealed that agglomeration in the starting mixture has a significant effect on the microstructure of the sintered specimens. High compaction pressure greatly eliminated the agglomerates and led to a uniform microstructure for the sintered specimens. However, when the Al content in the starting mixture was too high, Al particles in the compacts prepared by the high pressure were largely sintered due to the high compact density so that most of the pores were closed. The present study indicates that a suitable compaction pressure is critical to obtaining superior Al2O3/Al supports.

Nanocomposites of hydroxyapatite (HAp) and collagen (Col) were prepared by a biomimetic coprecipitation method under controlled pH and temperature. Transmission electron micrographs showed that the c-axis of HAp nanocrystals aligned along collagen by a self- rganization mechanism; a very similar alignment to bone's structure was found in the sample prepared at nearbiological conditions, i.e. pH8–9 and 40'C, which consisted of fibers with length of 20μm. From the material scientific point of view, therefore, osteoblasts may control the chemical condition in a small area around the cells to pH 8–9 as well as supply raw materials of bone, hydroxyapaite and collagen, at the initial state of osteogenesis. The biocompatibility of the composites was examined by animal tests using beagles. The composites were absorbed and new bone was formed as rapidly as a bone remodeling process. The HAp/Col composites prepared by biomimetic process were expected to be applicable as filler materials changing to new bone instead of autograft.

A new method of X-ray stress measurement was proposed to estimate non-destructively the steep residual stress distribution in the surface layer of ground Si3N4. We assumed an exponential decrement of the residual stress near the ground surface, and derived a formula for the lattice strain as a function of sin2Ψ. In the experiments, the diffraction angles were measured on the ground surface for a widest possible range of sin2ѱ using an Ω-goniometer. In order to measure the diffraction angle at very high sin η values, a scintillation counter was located on the -η side and an incident X-ray beam impinged on the ground surface with a very low angle from the +η side using the glancing incidence X-ray diffraction technique. A strong non-linearity was found in the 20-sin2ѱ diagrams especially at very high ѱ -angles. From the analysis of non-linearity, the stress distribution in the surface layer was determined. Tine residual stress took the maximum compression of 2 GPa at a depth of about 0.5 μm from the surface, and then diminished to zero at about 25 μm in depth. In the close vicinity of the ground surface, the compressive residual stress was relieved because of both the surface roughness and microcracking induced during the grinding process.