The sintering of intermediate powder articles based on oxide ceramic is examined from the standpoint of diffusion mass transfer. Two types of powders, differing by the preparation methods, are used in practice. As a rule, the more coarse powder is usually obtained by mechanical comminution while the other powder, characterized by a high dispersity and content of different types of crystal lattice defects in the particles, is obtained by chemical methods, such as precipitation from solutions, heterophase interaction, cryo- and plasma-chemical treatment, and so forth. It is shown that when intermediate articles are sintered they are compacted and hardened by different physical mechanisms.