LnTs 1DEq

They calculated a ratio of sintering onset to melting temperature that is in good agreement with experimental data for sintering of nanocrystalline metals. In 1950, Herring developed the classical scaling rule for the effect of the particle size on sintering time (Ref 38). Assuming operation of a single sintering mechanism, the time/ to achieve the same sintering condition is related to the powder particle size D by:

where n is the exponent that has a value of 3 if the main sintering mechanism is volume diffusion and a value of 4 if the main sintering mechanism is grain boundary diffusion. Considering an Arrhenius expression for temperature, the sintering temperature dependence on the particle size becomes:

where Q is the activation energy for the predominant sintering mechanism, R is the universal gas constant, D1 and D2 are the different powder particle sizes, and T1 and T2 are the respective sintering temperatures. Reasonable agreement of experimental and calculated data has been found for Al2O3 and TiO2 (Ref 26, 39).

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