This paper introduces the spouted bed chemical vapor deposition (SBCVD), an alternative technique to fluidized bed CVD for the coating of particles. The raison d'etre of SBCVD is first presented, followed by a literature survey of corresponding applications. Then, research performed in the authors group is detailed, concerning the use of SBCVD for the superficial doping of superalloy powders that are used as raw material of bond coats in thermal barriers applied on turbine blades. Deposition of Re from di-rhenium decacarbonyl (Re_2(CO)_(10)) is investigated due to both the reported improvement of the high temperature behavior of Re-doped superalloys and to the challenge of a low temperature CVD route for the processing of metallic Re. Transport properties of Re_2(CO)_(10) namely vapor pressure as a function of temperature are investigated first. Finally, SBCVD of Re and Ru on the surface of as received commercial NiCoCrAlYTa powders is performed. The morphology and distribution of the two elements on the surface of each particle are investigated with scanning and transmission electron microscopy combined with energy dispersion spectroscopy.
展开▼
