Synthesis, morpho-structural characterization and electrophoretic deposition of aegirine obtained by the hydrothermal method in the Si-Fe-Na-H2O system

Abstract

Aegirine belongs to a group of minerals known as inosilicates. In this study, a fast and efficient procedure is proposed for the synthesis of aegirine nanoparticles by means of the hydrothermal process, starting from a suspension of simple hydroxide/silicate precursors. Structural properties of the obtained mineral were assessed by the XRD technique. It was found that aegirine was the only crystalline phase present. The expected needle-like morphology, characteristic of inosilicates, was confirmed by scanning electron microscopy (SEM). Through an appropriate selection of solvents and dispersants, an electrophoretic deposition and immobilization of aegirine on stainless steel was achieved. Native layers of aegirine displayed a very smooth morphology, while after calcination, a detachment of the layers from the stainless steel substrate and the appearance of cracks in the coating was observed. This phenomenon could be prevented by the use of appropriate additives. SINTEZA, MORFO-STRUKTURNA KARAKTERIZACIJA I ELEKTROFORETSKA DEPOZICIJA EGIRINA DOBIJENOG Si-Fe-Na-H 2 O SISTEMA HIDROTERMALNIM POSTUPKOM Egirin je mineral inosilikatnog tipa. U ovom radu je opisan brz i efikasan hidrotermalni postupak za sintezu nanocestica egirina, polazeci od suspenzije jednostavnih hidroksida/silikata kao prekursora. Strukturne karakteristike dobijenog minerala su proucavane XRD metodom (rendgenska difrakcija praha), pri cemu je utvrđeno da se on sastoji iskljucivo od kristalne faze. Primenom SEM  metode (skenirajuca elektronska mikroskopija), potvrđena je iglicasta struktura minerala, karakteristicna za inosilikate. Odabirom odgovarajuceg rastvaraca i desperzanta, izvrsena je elektroforetska depozicija i imobilizacija egirina na nerđajucem celiku. Nativni slojevi egirina su posedovali glatku morfologiju, međutim, nakon kalcinacije uoceno je odvajanje prevlake od nosaca od nerđajuceg celika i pojava naprslina. Ovo se može spreciti upotrebom odgovarajucih aditiva. HIGHLIGHTS Fast and efficient synthesis of inosilicate aegirine nanoparticles by a hydrothermal process from hydroxide/silicate precursors was herein proposed Structural properties of the obtained mineral were studied by XRD and SEM techniques Electrophoretic deposition and immobilization of aegirine on stainless steel was achieved Native layers of aegirinedeposits on stainless steel had a very smooth morphology The addition of additives prevented detachment of the layers from the substrate and the appearance of cracks