Electrical and thermal tortuosity in powder compacts

A simple equation to calculate the effective mean path to be travelled by the heat flow or electrical current in a porous powdered material is proposed. In this equation, the effective mean path is a function of the sample porosity degree and the tap porosity of the original powder. This latter parameter determines to a great extent the compact pore structure, since it depends on the powder particle size, shape and distribution. The proposed equation has been validated using real metallographic images from sintered powders compacts. For measurements, a computer program, based on the Pathfinding A* Algorithm, has been developed. Results are in very good agreement with theoretical predictions. The proposed equation can be useful to model the electrical and thermal conductivity of sintered compacts.