Tarnishing kinetics of powders with lognormal particle size distributions

Equations are derived for the reaction kinetics of powders in which a particle of size D reacts according to dFD/d(tz)=(kz/βD)(1 –βF)m and which have lognormal, truncated lognormal or composite lognormal particle size distributions. This leads to a method for estimating such kinetics for powders with arbitrary particle size distribution.For β= 1 and either linear kinetics (z= 1, m=⅔) or parabolic kinetics (z=½, m= 0.43) lognormal powders with 0.2 < σ < 1.2 will approximately obey the same equation with median size for D and with m and ln k approximately linear functions of σ.