(206d) On-Line Apcvd of Sno2 Coatings on Glass

On-line atmospheric pressure chemical vapor deposition (APCVD) is a critical technique used to deposit coatings on float glass and glass containers and is responsible for the industry-wide production of approximately 110 million ft2/year of value-added products. The primary product produced in this manner utilizes a fluorine-doped SnO2 layer as a low-emissivity coating. This conductive layer reflects in the far-IR region yielding improved energy performance in architectural applications.

Although APCVD is a cost-effective method for on-line coating on glass, improvements in process efficiencies are expected to result in reduced solid waste generation and disposal, lower raw materials usage, and a reduction in energy consumption. Therefore, significant drivers exist for developing the fundamental understanding of the APCVD process that will lead to an increase in the process efficiency [1].

In this presentation a fundamental framework for SnO2 deposition in an impinging flow geometry, developed using computational fluid dynamics (CFD), will be presented. The current CFD model explicitly accounts for homogenous reaction in the gas phase, heterogeneous reaction on the glass surface, thermal effect of the impinging jet on the glass, and the flow characteristics in the confined coating zone. A comparison of CFD model results with experimental data will be described. It will be shown that the experimentally observed spatial distribution in the deposition rate is successfully captured by the model and the wave shape in the deposition profile can be explained with boundary layer separation. Finally, the impact of these findings on potential process efficiency improvements will be discussed.

References

[1] M. D. Allendorf. Research needs for coatings on glass. Summary of the U. S. Department of Energy roadmapping workshop. Thin Solid Films, 392:155?163, 2001.