New Research


Visualization of gas elements released from solid materials by fracturing

Material testing apparatus with a mass spectrometer and a high-speed microscope

Prof: Hidetoshi Kobayashi, Associate Prof: Keitaro Horikawa, Assistant Prof: Kenichi Tanigaki

   We have studied the fracture phenomenon of solid materials with hydrogen charging. Recently, the methods to utilize hydrogen have been developed as a promising energy source in the future, such as fuel cell system. Metallic materials are widely used as the component of the hydrogen energy system at present. However, it is known that all of the metallic materials are weakened by the effect of hydrogen absorption (Hydrogen embrittlement). Thus, it is important to reveal the effect of atmospheric hydrogen on the mechanical properties of metallic materials in order to establish the complete hydrogen energy system. Atomic size of hydrogen is the smallest and diffusivity of hydrogen in the solid material is very high. In addition, the hydrogen amount affecting the embrittlement is as low as the order of 1 ppm. Thus, it was difficult to clarify the hydrogen behavior in the hydrogen embrittlement so far. Based on this background, we have developed a new testing apparatus, which can monitor the hydrogen-related gas evolution and the microstructural image at the same time (Figure 1). This apparatus is composed of tensile testing machine, mass spectrometer (M/e=1~400, 1 sec) and high speed microscope (2000 fps) installed in the ultrahigh vacuum chamber (10-8 Pa). By using this apparatus newly developed, we have revealed the information of the hydrogen trapping state and the hydrogen amount in the microstructure when the metallic materials are embrittled by atmospheric hydrogen.

Strength of Structure and Materials Group
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