Effective thermal expansion coefficient of a sintered glass–eucryptite composite

The paper focuses on a glass–ceramic composite consisting of lead borate glass matrix containing isolated eucryptite granules (hereafter called inhomogeneities) having negative thermal expansion coefficient. We discuss the dependence of the overall thermal expansion on the size of the particles and the temperature of sintering as well as the process of the diffusion of lithium from eucryptite into the glass matrix. The latter leads to the formation of interphase zones between the matrix and inhomogeneities. The overall thermal expansion coefficient is measured experimentally and modeled using various micromechanical schemes. The best agreement for the entire range of variation of the eucryptite volume fraction is provided by Maxwell homogenization scheme.