Liquid spray vs. gaseous precursor injection — Its influence on the performance of particle coating by CVD in the fluidized bed

Aluminum coatings were created onto glass beads by chemical vapor deposition in a fluidized bed reactor at different temperatures. Two different routes were examined. First, tri-isobutyl-aluminum (TIBA) vapor was enriched in nitrogen and thermally decomposed inside the fluidized bed to deposit elemental aluminum. On the other hand, liquid injection of TIBA via a two-fluid nozzle directly into the fluidized bed was tested. To ensure homogeneous coating on the bed material, the fluidizing conditions necessary to avoid agglomeration were investigated for a broad range of temperatures. Also, different glass types and pretreatments of the substrate surface were investigated to elucidate the influence of the surface chemistry on the growth and morphology of the layers deposited.