Preparation And Characterization Of Zirconium And Silicon Based Ceramic Pigments With Core-Shell Structure

Zirconium and silicon based ceramic pigments,as ones of the most widely used pigments in industrial production,have huge demand and rich colors.The existing products of zirconium and silicon based pigments have been lagging behind the development of technology.In particular,the non-contact ceramic ink-jet printing technology under the guidance of CNC is changing the existing industry.The ink-jet technology can meet the finer,more accurate,and more multivariant decorative measure.The advantage of ceramic ink-jet printing is incomparable with traditional screen printing technology.However,one of the factors that restricts the development of ceramic inkjet printing technology is that the development level of ceramic pigments has not been improved,especially the ceramic pigment with core-shell structure.In order to meet or catch up with the development of ceramic inkjet technology in the future,the research on nano-size ceramic pigments is indispensable.Therefore,we select zirconium and silicon ceramic pigments as the research object,focusing on the core-shell structure and nanoscale of the ceramic pigments.Through the structure design and morphology optimization,the related research is carried out on the encapsulated black ceramic pigments and hematite–silica red inclusion pigment,and the main results and the contents are as follows:For the first time,the nano-size carbon spheres（CSs）prepared by hydrothermal method are used as carbon sources,depending on the rich and abundant oxygen functional groups on the surface,which can solve the problem of low encapsulation rate and poor chromaticity performance caused by the traditional carbon source（carbon black）,which is not hydrophilic and easy to aggregate.Zr⁴⁺and Si⁴⁺bond on the surface of CSs to form precursor inclusion layer through electrostatic adsorption and surface precipitation.During the calcination process at 1050℃,the zirconium silicate coating is formed in situ on the surface of CSs.The results indicated that a dense zirconium silicate coating layer was formed with high encapsulation rate,which protects the inner CSs from oxidation,and enables the pigment to achieve a deep black hue with L*value of 22.21 consequently.When it was applied to the transparent glaze at 1100℃,it showed a good chromaticity.The design of zirconia-silicon double shell has made full use of the advantages of the surface and spherical morphology of the CSs.In this way,we prepared the CSs@SiO₂@ZrO₂ precursor.In the process of calcining without mineralizer,the design of double shell improves the uniformity of transfer diffusion.The CSs@ZrSiO₄ pigments can be prepared at 950℃,and the spherical morphology and mono-dispersity of the CSs are retained on the basis of high encapsulation rate.Therefore,the CSs@ZrSiO₄ pigments has a brightness value of 6.95 and an average particle size of 464.87 nm.Compared with the CSs@ZrSiO₄ encapsulated black pigments prepared in the second chapter,the pigments prepared by double shell structure can maintain 48 h dispersion stability in glycol.A high encapsulation rate and mono-disperse hematite–silica red inclusion pigment was prepared by a simple two-step process.In order to obtain excellent pigment morphology,we use the hydrothermal synthesized of nanocrystallineα-Fe₂O₃ particles as the colorant,and use the classical St?ber method is use to encapsulate the colorant uniformly.The results indicated that the as-prepared pigments had the characteristics of narrow particle size distribution,high dispersion and good sphericity.The particles sizes are in the range of 180-220 nm with the mean particle size of 202 nm.Theα-Fe₂O₃@SiO₂reddish pigments were uniform and well-dispersed in solution.In addition,the pigments with different shell thickness were also prepared,and the effect of shell thickness on the color performance of the pigments was discussed.