Study Processing of Ceramic Material

A concept is presented which relates the sinterability of a powder compact to its particle arrangement as defined by the distribution of pore coordination numbers, i.e. the number of touching particles surrounding and defining each void space. Previous thermodynamic arguments suggest that pores will only disappear when their coordination number is less than a critical value. The coordination number distribution of an agglomerated powder is discussed with respect to the size of the multiple-particle packing unit, consolidation forces and phenomena develop during sintering. One pertinent conclusion is that the multiple-particle packing units, density and support grain growth as sintering initiates. Grain growth and rearrangement processes decreases the coordination number of remaining pores to allow them to disappear during latter states of sintering. Porosimetry and direct observations of powder compacts of 1 micron Al2O3 heat treated between 600 and 1600 deg C are consistent with this concept.