Influence of process parameters on expansion behavior of foaming glass

Deformation behavior of foaming glass is examined by experiments as well as finite element analysis on some conditions of the amount and the distribution of a foaming agent. The expansion of glass powder compacts in firing is not proportional to the amount of the added foaming agent, because the skin, the dense region produced by the loss of gas from the surface, tends to obstruct the expansion. The skin also makes the glass foam rounded. In the glass powder laminates, the expansion of a foaming layer is constrained by the other, dense layer. Configuration of the dense regions, of which apparent viscosity is much higher than that of porous regions, is important to control the graded structures as well as the size and the shape of the glass foam products.