Initial stage sintering kinetics

In the study by Nordstrom and Yost, the sintering behavior of thick film Au conductors was monitored by electrical resistance measurements and scanning electron microscopy. Initial-stage sintering kinetic equations coupled with resistance/neck area correlations were used to develop a relationship between resistance R and sintering time T ... 

Table 4.2. Summary of kinetic equations for various mechanisms of initial stage sintering...

Since the introduction of a mathematical model for sintering by Kuczynski [12] numerous other models have been proposed. Reviews of these sintering kinetic models are given in references [13—19]. This description of sintering kinetics is organized into initial, intermediate, and final stage kinetic models. 

Solid state sintering was discussed previously in this chapter. The sintering kinetics depend upon the rate determining step, which can be either viscous flow, grain boundary diffusion, or lattice diffusion. These sintering kinetics are summarized in Tables 16.4 and 16.6 for the initial and intermediate stage and Section 16.3.2.3 for the final stage. 

Fuentes addressed the issue of deactivation kinetics in general [5], and of sintering kinetics in particular [6,7], and found an important discrepancy between experimental results and use of the PLE as a fitting tool. He observed that in most cases metallic dispersion reached a quasistationary plateau after an initial stage of fast changes in dispersion. That was at odds... 

D.L. Johnson and I.B. Cutler, Diffusion sintering, I initial stage modek and their applications to shrinkage of powder compacts, II intial sintering kinetics of alumina. /. Am. Ceram. Soc., 46 (1963) 541. 

P. H. Shingu, Effect of Competitive Mechanisms upon Densihcation during the Initial Stage of Sintering and Sintering Kinetics of Iron, Ph.D. Thesis, Northwestern University, 1967. 

Many aspects can be studied from the kinetic equations, as densification rate, determination of sintering mechanisms, and activation energy. The equation developed by Coble allows to estimate the sintering mechanisms for the initial stage, based on the two spheres Frenkel s model, as indicated in the Eq. 15 [43] ... 

The deactivation of bulk iron oxide during methane combustion has been studied. The observed deactivation behaviour has been explained as the result of two simultaneous deactivation mechanisms. In the initial phase of reaction both are in operation and the activity drops rapidly as a consequence of both catalyst sintering and of the depletion of lattice oxygen in the outer layers, due to a partial reduction of the catalytic surface. In later stages, catalyst deactivation is almost exclusively due to sintering imder reaction conditions. A kinetic model of deactivation is presented, together with the physicochemical characterization of fresh and partially deactivated catalysts. 

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