Evaluation of sintering stresses of an Al_2O_3 powder with a self-loading apparatus

摘要

The sintering stress of an Al_2O_3 powder, sigma_s, is evaluated from an equation sigma_s = F_s/rho S_a, where F_s is the uniaxial tensile force necessary to just stop the sintering contraction, p is the relative density, and S_a is the cross-sectional area. During densification, sigma_s increases to the maximum at a relative density of 85 percent , and then abruptly decreases. The variation of sigma_s in the intermediate sintering stage suggests a simple cubic packing of particles. Densification in the final sintering stage is explained by shrinkage of the pores at the corners where four tetrakaidecahedra meet. The present surface tensions of the Al_2O_3 powder evaluated from the sigma_s roughly equal a reported value.