Estimation of sintering pressure during the pore fragmentation via coordination number and reversal of curvature

Abstract

Sintering is a process of removing pores from a powder compact, and the pressure to shrink pores is called sintering pressure. In this research, to explain the improvement of sintering in accordance with pore fragmentation, the change in the number of grains per pores (coordination number) was highlighted, and the sintering pressure was expressed and calculated in terms of a coordination number. To this end, variables affecting the sintering, such as grain size, pore size, direction of curvature, and dihedral angle, were expressed as the coordination numbers. Evaluation of the sintering pressure for bimodal pores present in 1 wt.% Al-doped ZnO showed that micron pores were expected to exhibit 21 kPa at the mode size, while submicron pores were evaluated to have 6.3–7.9 MPa. This shows that the pore fragmentation, that can be induced by initial heat treatment under mild external pressure, has the effect of improving the sintering pressure by approximately 300 times.