Abstract
By the condition of system free energy minimization, it is theoretically proven that the dihedral angle of a closed pore on grain boundaries does not depend on the internal gas pressure of closed pores, and that it would satisfy the Young-Dupré equation at equilibrium state. In the measurement of dihedral angle, it is pointed out that the equilibrium state would be changed with transformation from closed pores to open pores. Moreover, the distribution of measured dihedral angle caused by sectioning and the change in the measured value of dihedral angle at high temperature are discussed.
