• Corrosion Science and Technology
• /
• v.7 no.6
• /
• pp.307-314
• /
• 2008

The influence of a moist atmosphere on $90^{\circ}$ domain switching under a sustained electric field, stress corrosion cracking of an indentation crack in water and an aggressive solution, and the relation between penetrating crack propagation and domain switching were studied using $BaTiO_3$ single crystal. The results indicate that enlarging the domain switching zone and crack propagation could be facilitated by a moist atmosphere or an aggressive solution due to the indentation residual stress. A moist atmosphere exerts remarkable influence upon the polarization of $BaTiO_3$ single crystal under a sustained electric field, and the surface energy of the c domain was much lower than that of the a domain. Domain switching ahead of a penetrating indentation crack tip was an essential requirement for crack propagation under constant stress.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.256-259
• /
• 2002

The critical currents of sintered $YBa_{2}Cu_{3}O_{6.5+\delta}$ were measured as the variables with the corrosive time in the humid air. The corrosive process was studied by means of the current changes. Ag coating on the textured YBCO and polytetrafluoroethylene (PTFE) coating on the sintered YBCO were prepared. The critical current densities of different YBCO samples with and without coatings were compared. Both Ag coating and PTFE coating can well protect YBCO from moisture and $CO_{2}$.