Open AccessEnvironmentally Benign Solution‐Based Procedure for the Fabrication of Metal Oxide Coatings on Metallic Pigments
Author(s) -
Bies Thorsten,
Hoffmann Rudolf C.,
Stöter Matthias,
Huber Adalbert,
Schneider Jörg J.
Publication year - 2020
Publication title -
chemistryopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 29
ISSN - 2191-1363
DOI - 10.1002/open.202000223
Subject(s) - thermogravimetric analysis , thermal decomposition , oxide , copper , inorganic chemistry , iron oxide , metal , materials science , scanning electron microscope , chemistry , urea , chemical engineering , organic chemistry , metallurgy , engineering , composite material
Aluminum pigments were coated with Fe 2 O 3 and CuO by solution‐based thermal decomposition of the urea nitrate compounds hexakisureairon(III)nitrate and tetrakisureacopper(II)nitrate. The deposition process was optimized to obtain homogeneously coated aluminum pigments. The growth of the surface coatings was controlled by investigation with scanning electron microscopy, energy dispersive X‐ray spectroscopy and static light scattering as well as infrared, X‐ray diffraction and thermogravimetric analysis. The iron precursor showed an incomplete decomposition in solution, incorporating traces of urea molecules inside the coatings while the copper precursor showed complete dissociation accompanied by in situ formation of amine complexes. The amount of organic residues resulting from ligand fragments in the final oxide coatings could be reduced to 22 % for the iron oxide and 12 % for the copper oxide by further temperature treatment in solution (259 °C). Colorimetric investigations of the obtained pigments revealed an excellent hiding power, outperforming the pigments used in current state‐of‐the‐art formulations.