The Identification of the Initial-Stage Sintering Mechanism: A New Approach

Abstract

In the preceding paper we have provided a relationship between neck size and surface area reduction based on the morphological changes accompanying the initial stage sintering of monosized spheres. It was shown that such a relation is dependent on both mechanism and particle coordination (powder packing fraction) in the following manner:

$$\frac{{\Delta S}} {{S_0 }} = K\left( {Bt} \right)^{\frac{m} {N}} \left( {\frac{{\Delta S}} {{S_0 }} \leqslant 0.5} \right)$$

((1))

Here ΔS/S_O is the normalized specific surface area reduction; t is the isothermal sintering time; B is a constant containing material properties, particle size, and temperature; and K, m, and N are constants for a given set of conditions dictated by the controlling mechanism. From theoretical models, N is expected to have a characteristic value for each mass transport mechanism. Examination of Eq. 1 reveals that a log (ΔS/S_O) versus log t plot will show a characteristic inverse slope of N/m if a single mechanism is operative. Since m can be determined from simple compact density determinations,¹ calculation of N is straightforward. Thus, ΔS/S_O has the same fundamental role in sintering kinetics as neck size data, without the inherent errors associated with measurements of the latter parameter.^2–4