Coalescence Growth of Smoke Particles Prepared by a Gas-Evaporation Technique

The growth of smoke particles by coalescence in which two or more single particles collide and unite in definite orientations has been studied. It is theoretically obtained that the mean size of particles increases linearly with height in a uniform flow of rising smoke, depending on the mass density of the smoke particle and its temperature. The relation is verified by measuring the size of MoO 3 particles in a uniform smoke at a constant temperature. The size and crystal habit of MoO 3 and WO 3 particles produced by burning metals in Ar–O 2 gas have been studied by electron microscopy and the growth of these particles is discussed.