Study On The Hydrothermal Synthesis Process And Chroma Characterization Of Fe₂O₃-SiO₂ Red Inclusion Pigments

In this paper,hematite-silica red pigment was prepared by hydrothermal method.Ferric chloride,TEOS solution was prepared as raw materials according to a certain proportion.Sodium hydroxide solution of 3 mol/L was used to adjust pH values of the hydrothermal solution.SiO2/Fe2O3 mass ratio,reactant concentration,the type and amount of mineralizing agent,hydrothermal treatment temperature,holding time and other parameters such as the filling materials,crystal structure of iron oxide are all impact the color presentation of the hydrothermally synthesized products.In the course of the experiment,the synthesizing conditions of hematite-silica red pigments was optimized and the optimum fomulation and experiment conditions were obtained,combined with the XRD analysis and the color presentation.The results revealed that the optimum pigment was synthesized under the conditions of SiO2/Fe2O3 mass ratio of 80/20,Fe3+reactant concentration of 0.015 mol/L,adding 0.12 g NaF,65%fill factor,and the hydrothermal reaction temperature 220?,holding time of 2 h.The as-synthesized hematite-silica red pigment was of L*=41.72,a*=18.41 and b*=7.84.The use of color Lab value and statistical analysis,by selecting the appropriate criteria and construct a discriminant function,to make a pre judgment on the new lab value of the sample color.And through the Matlab program to the sample color reflected in the Lab space,and can predict the results of visual comparison.