Some cases of instability of free sintering of powder materials with matrix containing rigid inclusions

Abstract

An explanation of some conditions under which zones of possible density reduce appear inside of a porous body during sintering is given. The described phenomena, related to shrinkage instability, is treated as possible manifestation of destruction in sintering process. Two main factors conditioning this phenomena are considered. The first is cased as by uneven distribution of the initial density, so by inhomogeneity of other parameters, which describe rheological properties and sintering potential within the sample. The second factor is related to inhomogeneity of porous structure. Peculiarities of be-porous body shrinkage are considered. As the main purpose of the study is quantitative analysis of instability phenomena, the simplest sintering model is used. Possible matrix flow arrangement should be expressed through the viscosity factors. Analytical assessment and numerical solutions, obtained for some ideal systems, are sensitive to restricted and unrestricted sintering conditions and generally correspond to results of Rai — Bordia and Olevsky — Molinary.