Preparation And Color Mechanism Of Spherical Fe-ZrSiO₄ Red Pigment For Ceramic Laser Printing

As the next generation architectural ceramic decoration technology,ceramic laser printing technology possesses broad development prospects and market potential.Ceramic laser printing technology has relatively high requirements on the granularity performance and solid fluidity of ceramic toner.Hence,pigments should be powder with suitable size,uniformity and spherical shape with smooth surface.Simultaneously,the iron zircon red pigment should possess excellent color rendering properties to fulfill the color stability of the iron zircon red pigment in the molten glaze.The sol-gel-hard template method which was a novel preparation method and was suitable for preparing spherical ceramic powders with different particle sizes was proposed in this thesis.The principle of this method was to prepare water-in-oil microemulsion by utilizing molten paraffin.After rapid cooling,the paraffin was solidified to form a spherical microemulsion reaction system,thereby controlling the gelation shape of the sol and obtaining spherical particles.In the preparation process,the precursor aqueous solution of the target powder was firstly dispersed in the molten oil phase composed of paraffin and cyclohexane.After rapid cooling,the droplets of the aqueous phase were fixed in the solid oil phase to form a stable oil-water interface template,waiting for the complete reaction in the aqueous phase.Finally,the model was removed by heating,and the spherical powder was obtained by calcining the precipitate.The spherical powder was prepared by this method,and then the micromorphology and particle size of the powder were characterized by SEM,laser particle size analyzer.The process factors,like the ratio of oil phase composition,the dosage of surfactant,the type and dosage of co-surfactant,dispersion mode were studied to explore their influence on the micromorphology of the spherical powder.The results indicated that the solidified paraffin made the aqueous phase and oil phase form an extremely stable template in the preparation process,so that the sol-gel reaction could fully occur in the aqueous phase.Surfactants made the oil-water interface have a short-term stabilizing effect in the liquid state,maintaining the spherical shape and size of the droplets.The chain length and the dosage of co-surfactant alcohol had an important influence on the sphericity and morphological regularity of the powder.Zirconia powder and iron zircon red precursor powder with a particle size of about 2?m could be prepared by this method and possessed good sphericity,narrow particle size distribution between 700nm-3?m.The dosage of the surfactant required in this method was minimal,and when the dosage reached 0.5 wt.%,the template could be removed by reheating and melting.To obtain the iron zircon red pigment with good color rendering properties,this thesis also proposed to utilize Fe F3 as the iron source to prepare the iron zircon red pigment by sol-gel method.The iron zircon red pigment was characterized by XRD,Raman,XPS,TEM,and visible light absorption,etc.,to analyze the relationship between the microstructure of the iron zircon red pigment and the concentration of Fe³⁺,to study the color rendering mechanism of the iron zircon red pigment,as well as the main source of pigment color.The results indicated that Fe F3 could be utilized as both iron source and mineralizer;the chromatic value of pigment was L*=53.45,a*=22.42,b*=18.57;the solid solution structure and the package structure existed in the iron zircon red pigment;when the ratio of Fe³⁺/Zr⁴⁺ in the pigment was less than 2.25mol%,the solid solution structure would be preferentially formed;when the ratio of Fe³⁺/Zr⁴⁺ in the pigment was more than 2.25mol%,the doping concentration of Fe³⁺ in the ZrSiO₄ crystal would decrease and caused the formation of ?-Fe₂O₃.Furthermore,when the concentration of Fe³⁺ in solid solution Fe-ZrSiO₄ exceeded 2.25mol%,the solid solution could also exhibit a good read.The color of the iron zircon red pigment was determined by the solid solution structure.