Monazite coatings on short alumina fibers using layer-by-layer assembly technique

Rhabdophane cerous phosphate particles were deposited on short alumina fibers, using an aqueous precursor and layer-by-layer assembly technique. A polyelectrolyte, Na+ salt of poly(acrylic acid), was employed for the surface modification of alumina fibers in the coating process. Subsequent heat treatment caused the transition of the coatings from rhabdophane to monazite. Dense, uniform monazite coatings on the alumina fibers were obtained by multiple coating steps. The precursor phase evolution was studied with differential thermal analysis/thermogravimetric analysis and X-ray diffractometry. The morphology and structure of the coatings were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry. The variables controlling the coating process are discussed.