1) Application of Microgravity for Technological Innovations

No mass transfer by convection currents in gasses and liquids exists, an effect of surface tension becomes strong and substances having different specific gravity disperse homogeneously under microgravity. It is impossible to obtain these unique circumstances such as microgravity on the ground. The tools for microgravity circumstances are a drop tower, rocket, space shuttle, and so on.
Our research purpose is to synthesize new and highly functional materials under microgravity. In order to reach the purpose mentioned above, we accumulate the information for the physical phenomena under microgravity such as diffusion, surface tension and heat transfer. At present, we are carrying out the microgravity experiments by two drop facilities mainly. One is the facility of the Japan Microgravity Center (JAMIC, Kamisunagawa, Hokkaido) obtained the microgravity circumstances of 10-5g for 10 sec. The JAMIC facility was constructed using a shaft of the abandoned underground coal mine having a depth of 710 m. Other is the HNIRI 10m drop tower obtained the microgravity circumstances of 10-3g for 1.2 sec attached linear motor braking system.


The JAMIC underground microgravity facility	The HNIRI 10m drop tower

Control Processing of Material's Properties

This research is carried out by taking advantage of computer simulation, to find radically new methods and design for manufacturing novel materials such as amorphous compounds, metal-based composites and porous materials under vacuum, high pressure and microgravity.

Research on New Composite Fe-C Alloy under Microgravity

To produce high performance materials of composite FeC alloys containing fine particle such as ceramics, the composite alloys are solidified under a microgravity environment produced by a drop shaft. When metal alloys melt, many phases with different specific-gravities are present and materials with different melting points separate and materials with different melting points separate from the matrix. Then, both the stirring rate and/or the cooling rate of the melt have a major influence on the properties of the product. These facts show a possibility of a new formation process of composite alloys with high wear-resistance, corrosion-resistance and heat-resistance, etc., by utilizing the microgravity of short duration.


Melting under normal gravity	Melting under microgravity

High Speed Heating and Cooling Technology by SHS Process Under Microgravity in a Very Short Time

When we a drop shaft for research under microgravity, it is necessary to utilize the experiment effectively because of the very short duration involved. Gravity usual influences the fluid behavior which is observed in liquid or gas phases. In this research, an experiment is carried out to melt speedily and solidify immediately intermetallic compounds by means of SHS process which can reach high temperatures in a very short time under microgravity, without being influenced by 1g.


Melt and solidify under normal gravi	Melt and solidify under microgravity

Surface Modification Technology of Fine Particles

The objective of the project is to develop particle surface modification technology by using low temperature gas plasma to improve the chemical or physical properties of solid surface. The applicability of the technology in space applications is also examined in microgravity environment.


Powder behavior in normal gravity	Fluidization phenomena in microgravity

Fabrication of high-efficiency crystalline solar cells under microgravity

High-efficiency crystalline solar cells such as CuInSe2 having homogeneous composition and uniform structure are fabricated by melting-solidification and heat treatment (selenization etc.) under microgravity circumstances. No mass transfer by convection currents in gases and liquids exists and substances having different gravity disperse homogeneously under microgravity circumstances. Homogeneous CuInSe2 was obtained under microgravity. Heterogeneous CuInSe2 was obtained under 1-g. From this result, it is expected that high-efficiency CuInSe2 solar cell can be fabricated under microgravity circumstances.


1-g	幍-g

CuInSe2 samples obtained under 1-g and 幍-g

Wettability of molten metal under microgravity

It is necessary for proceeding the microgravity research efficiently that we well understand the unique phenomena under microgravity such as no convection currents, non-contact and homogeneous dispersion. As one of them, effect of surface tension become remarkable under microgravity and wettability is affected. In this research, effect of microgravity on wettability of molten metal such as In is researched using the microgravity facility of our laboratory (10-3g, 1.2sec).


1-g	幍-g

Molten Indium on silica glass under 1-g and 幍-g

Development of manufacturing technology of semiconductor with hemispherical surface

Photoelectric converting semiconductors such as Ge and InP having regularly arranged hemispherical surface are expected to improve photo absorption efficiency. That semiconductor with hemispherical surface can be only fabricated under microgravity circumstances that influence of the surface tension appears remarkably. This research aims at the preparation of semiconductor with hemispherical surface by means of melting-solidification under microgravity.

Ge having hemispherical surface fabricated under 幍-g

The advanced combustion technology under a microgravity environment

　　　The interaction of flame of droplet arrays combustion is investigated as the fundamental study of engine. In this study the microgravity environment is adopted because of the future of non natural convection. The relationships of combustion rates of droplets and spacing distance of each droplet have been measured.
The flame propagation in coal dust cloud is investigated as the fundamental study of pulverized coal combustion boiler. The microgravity environment is adopted because of easiness of making homogeneous dispersion of particles in air. It becomes clear that the oxygen concentration has strong positive effect on flame propagation rate. The increment of total pressure decreases flame propagation rate. The existence of carbon dioxide also decreases flame propagation rate.


Spacing distance of each droplet = 6mm	Spacing distance of each droplet = 14mm
	Burning behavior of droplet arrays
Spacing distance of each droplet = 20mm

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