Zairyo-to-Kankyo

Adsorption behavior of gaseous hydrogen on metal surface has been briefly reviewed, focusing on fundamentals for hydrogen entry that causes degradation of mechanical properties. The measurements for the adsorbed sites and states by means of thermal desorption spectroscopy and the work function are presented. Studies on the isotherm and adsorption kinetics are also presented. The effects of alloying elements and impurities on hydrogen coverage are summarized as well as the effects of gas components.

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Recently, oxidation and erosion resistant ceramic coating materials have been used for high temperature plant components. Evaluation of physical and mechanical properties is important to select suitable materials and to predict their service duration. Hardness is generally used as an indicator of mechanical properties. Contact pressure is regarded as a representative of the hardness under an indentation process. Therefore, mechanical properties of ceramic coating materials were evaluated from the viewpoint of behaviour of contact pressure obtained from quasi-static and dynamic indentation tests at room temperature. The dynamic indentation tests was also conducted at 723 K. As a result, the contact pressure of the ceramic coating materials depended both on test temperature and coating thickness. The performance of ceramic coating materials used as actual components under erosion by solid particle impact was estimated from the contact pressure behaviour and calculated indentation behaviour of impact particles.

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