| With the advancement of ceramic production and decoration technology, people's requirements for ceramic pigment are increasing. However, due to the limits of producing and process conditions, it is very difficult for us to achieve major breakthroughs and improvements on process approaches and therefore the size of pigment particles could not be further reduced. Besides, encapsulation pigment prepared through the existing technologies usually exhibits some problems about low efficiency of encapsulation, larger particle size, wider size distribution, heavy pollution and so on. At the same time, the emergence and development of some new decoration and preparation methods, such as ceramic ink-jet printers, dry powder mixing technology and so on, make new demands on ceramic pigment and those with sub-micron particle size, as well as fine high temperature stability and bright colors, will be the focus of new development. The economical synthesis of nano/sub-micron encapsulation black pigment has not been reported currently, so the development and application of black and gray encapsulation pigments will be put more emphasis on in the future and in a meanwhile impose a tremendous challenge on the traditional cobalt black and tin-antimony gray pigment, whether in its coloration or in the manufacturing cost.The method of liquid oxidants modification on carbon black (CB) was adopted and the law of oxidation process was also studied. It was showed by the experiment results that, after oxidative modification, the pH values on the surface of CB decreased, while the volatile contents increased. However, the infrared spectrum of liquid oxidants modified CB, which didn't have obvious characteristic differences with that of original CB, presented that there mainly existed carboxyl and hydroxyl groups on its surface, which also was proved through the analysis of XPS. What's more, the oxidation capacity of liquid oxidants directly affected the chemical properties on the surface of CB and its dispersion stability in the aqueous system. Accordingly, the stronger the oxidation capacity of liquid oxidant, the more the electronegativity increased on the surface of carbon black particles, the less the isoelectric point became. In addition, the more the total acid contents of oxygen-containing functional groups on the surface of CB, the stronger the acidity became, the better dispersion stability turned out to be. This attributes to the rised hydrophilic and double-potential layer because of an increase of oxygen-containing functional groups on the surface of CB.Basing on those works above, the method of surfactant modification on liquid oxidants modified CB was adopted to further improve the dispersion stability of CB in the aqueous system. It was indicated by the dispersion stability test and Zeta potential test that cationic surfactant (CTAB) could make the charge on the surface of CB particles reverse in acidic solutions, while non-ionic surfactant (PVP) could reduce the negative charge on its surface.Modified CB powder coated by SiO2 (SiO2@CB), with TEOS and ammonia as raw materials, could be prepared under experimental conditions respectively by st?ber method and sol-gel-precipitation method and the mechanism of its synthesis was studied. Also, its surface morphology and phase composition of coating were systematically analyzed in terms of X-ray diffraction (XRD), scanning electron microscopy (SEM), Zeta potential test and color measurement. It was showed by the test results that there existed a layer of mashed amorphous silica on the surface of SiO2@CB, in which there was many nano-holes. Also, a significant change of Zeta potential on the surface of SiO2@CB particle took place and its isoelectric point greatly offset to the direction of lower pH. Besides, X-ray diffraction (XRD) analysis of SiO2@CB presents no significant changes in the diffraction pattern of CB after high temperature treatment above 500℃for a certain time, suggesting that the presence of SiO2 shell structure could prevent the oxidation and decomposition of CB under high temperature. Moreover, the amorphous SiO2 coating transformed to cristobalite phase to stay on its surface stablely. What's more, the mechanism of coating mainly showed that the amorphous SiO2 nuclei generated from the hydrolyzation of TEOS under basic conditions nucleated on the surface of CB particles in the form of non-homogeneous nucleation, and grew up in the form of homogeneous nucleation to form the coating. At the same time, SiO2 nuclei had a negative charge, while CB dispersion surface had a small amount of positive charge after surfactant (PVP, CTAB) modification, so the core-shell structure could be formed due to the electrostatic interaction between SiO2 nuclei and CB particles.Modified CB powder coated by ZrSiO4 (ZrSiO4@CB) were also tried to prepare by the layer-by-layer self-assembly technology, as well as hydrothermal method and traditional co-precipitation method, and the surface morphology and phase composition of modified CB were analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and color measurement. It was indicated by the test results that ZrSiO4 crystal obtained by hydrothermal method under experimental conditions exhibited a flaky shape, and there existed some small particles over its surface with the average particle size of approximately 100nm. Zircon particles prepared by co-precipitation method under experimental conditions melt together with Na2SiO3, whose X-ray diffraction (XRD) analysis also proved that mineralizer (NaF) can reduce the temperature of zircon formation.
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