Study of Ni/Al₂O₃ Deposition on Metallic Surface using RF Plasma Process

This work is aimed at acquiring knowledge on successive deposition of alumina and nickel coatings on a metallic substrate using an RF plasma torch. The composition and morphology of various Ni/Al₂O₃ steam reforming catalysts, prepared by plasma spraying of precursor nickel suspensions, are studied in this work. As Ni/γ-Al₂O₃ is a well known reforming catalyst it was decided to study the deposition of a particular catalytic formulation on a metallic substrate. The purpose of this study was to find the means of building 2D monolithic catalysts by plasma deposition. Since 2D monolithic catalysts are non-porous, their specific areas available for hosting the catalytic reactions are low. Thus, It is essential to have very good dispersion of the active catalytic sites. Such dispersion is only possible only if the deposit can take place at the nanometer scale. The suspension plasma spraying is assessed for its ability to produce such structures. This method permits the formation of nanocrystalline structures within a few seconds. The main difficulty is the control of the various spraying parameters in order to obtain satisfactory deposition. The Ni/γ-Al₂O₃ catalysts so obtained are characterized by scanning electron microscopy, field electron microscopy and X-Ray diffraction.