CoAl2O4 blue nanopigments prepared by liquid-feed flame spray pyrolysis method

Abstract

CoAl 2 O 4 pigments were synthesized through Liquid-Feed Flame Spray Pyrolysis (LF-FSP) method using metallorganic precursors of cobalt propionate and alumatrane. The precursors were dissolved in ethanol and aerosolized into a methane/oxygen flame where it was combusted to result in nanopowders at a single step. The resulting nanopowders were collected in electrostatic precipitators and analyzed by x-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), colorimetry, Field Emission Scanning Electron Microscopy (FE-SEM) and BET (Brunauer-Emmett-Teller) nitrogen adsorption. Results show formation of single phase blue nanopigments, suggesting that LF-FSP is an excellent method to produce nanoparticles with high quality in a continuous process for new industrial applications. The nanoparticles presented spherical morphology with specific surface area of 50 m 2 /g, corresponding to average particle size of 27 nm. The pigments were calcined at 500, 600, 800, 1000, 1200 and 1300 °C, aiming to find the color stability whereby the colors were measured using the color space CIE L*a*b* under standardized D65 light. The brightest and bluest was obtained at calcination temperature of 1200°C and its application into a glaze was carried out at 1200 °C to evaluate the color performance and stability after a decoration process. Finally, LF-FSP produced pigments were compared with those produced by solid state reaction. Differences in the color due to the average particle size and process conditions were observed. It is possible to obtain new hues for ceramic applications by LF-FSP method.

Synthesis and characterization of nano-ceramic pigment Co0.5Zn0.5Al2O4 via polyacrylamide gel method

“…It is well known that the method of synthesis plays a key role in influencing the final desired properties of nanopigments. A variety of techniques, such as solid state reaction (Hagiwara et al , 2010; Suzuki et al , 2007), combustion (Merino et al , 2015; Salem et al , 2012), sol-gel (Kurajica et al , 2012; Salavati-Niasari et al , 2009; Sales et al , 1997; Yu et al , 2009), hydrothermal (Yu et al , 2009), micro-emulsion (Giannakas et al , 2007), polymeric precursor (de Souza et al , 2009) and liquid-feed flame spray pyrolysis method (Granados et al , 2015; Granados et al , 2016), have been developed successfully obtaining cobalt aluminate oxides. Although Co x Zn 1-x Al 2 O 4 pigments have been synthesized by different techniques, no study has been done dealing with the use of polyacrylamide gel method.…”