Abstract
In order to simulate the influence of microgravity on the reaction between gas and metallic powder, the experiments of heating the titanium wire specimens with 0.5 mm diameter by electric current in 0.5 absolute atmospheric pressure (0.5 kg/cm2) of pure nitrogen gas environment under normal gravity (g=9.8m/s2=1G) and microgravity (g=μG) using a drop shaft that enables 10 seconds duration of microgravitational condition is carried out. The influence of gravitational acceleration on the morphological changes in optical microscopic microstructures of the specimens is studied. The nitriding reaction becomes active under microgravity by temperature increase of the specimens with the heating time due to the suppression of thermal convection and the cooling effect of the nitrogen gas on the specimens is reduced. The results of the present study are explained by the gravitational acceleration effects.
