An experimental study of heat transfer and particle deposition during the outside vapor deposition process

An experimental study has been carried out for heat transfer and particle deposition during the outside vapor deposition process. The surface temperatures of deposited layers, and rates, efficiencies and porosities of particle deposition were measured. For the characterization of the burner used, temperature distributions in the flame were measured using thermocouples and the evolution of the particle sizes was obtained-using a thermophoretic sampling technique and TEM (transmission electron microscope). Of particular interest are the effects of the traversing speed of the burnet, the flow rate of the chemical, and different passes of burner traverse. It is shown that the axial variation of the surface temperature can be assumed to be quasi-steady in the moving frame with the burner. As the traversing speed of burner is increased, the deposition rate, the efficiency and the porosity increase due to the decrease of surface temperatures. As the flow rate of the chemicals is increased, both the thickness of deposition layers and the surface temperature increase. Deposition rate also increases, however, deposition efficiency decreases for tests done. Later passes in the early deposition stage result in higher surface temperatures due to larger thickness of porous deposited layers, which cause the deposition rate, efficiency and porosity to decrease. (C) 1997 Elsevier Science Ltd.