SNMS investigations of thermally sprayed coatings

Abstract

Abstract Surface protective coatings are commonly used in order to protect the bulk materials against corrosion and high temperature oxidation. The present publication discusses the morphology of high-velocity oxygen fuel (HVOF) sprayed MCrAlY coatings obtained from CoNiCrAlY particles (8 wt.-% Al) before and after electron beam (EB) treatment. The latter process was applied in order to achieve a homogeneous and refined structure free of pores and oxides. The microstructure and phase modification of the coatings before and after the EB remelting were characterized by scanning electron microscopy (SEM) and X-ray diffraction technique. Using the sputtered neutral mass spectrometry (SNMS) technique, the element contents (O, N, Co, Ni, Cr, Al, Y) of the coating in as sprayed and after EB irradiation were examined. Experiments have shown that while the Co concentration remains practically unchanged, significant changes in Cr, Ni, Al and Y concentrations occurred. Also, the N and O contents are lower compared to those of the as sprayed coatings.