Synthesis And Characterization Of Black Zircon Encapsulated Carbon Black Ceramic Pigment

Under the condition of the improvement of low carbon consciousness and healthy environmental protection,more and more attention was given to heavy metal ion dissolution of ceramic products.So a new type of environmentally friendly black ceramic pigment is to prepared by ceramic enterprises to replace the traditional spinel cobalt black ceramic pigment.Carbon black is a good black pigment,cheap and pure.However,carbon black cannot be directly used as ceramic pigment due to the oxidation at high temperature.This paper present a new ceramic pigment—black zircon encapsulated carbon black ceramic pigment which has the structure of jujube cake.Compared to other encapsulated ceramic pigment,the full coverage of carbon black is required,or else,the pigment will become gray or white due to the oxidation of carbon black.Such a high encapsulation ratio requires to solve two obstacles:?1?the problems of zircon precursor particles encapsulated carbon black particles,hydrophobic carbon black is difficult to disperse in aqueous solution,so the dense layer of zircon hardly form on the surface of carbon black.?2?Formation of the dense zircon layer.The decomposition,crystallization and solid phase reaction process of zircon precursor have the volume change,which is harmful to the densification of layer.This paper researches the preparation conditions of encapsulated carbon black ceramic pigment prepared by sol-gel-spray pyrolysis method and mesoporous collapse method.The effect of preparation conditions on the coating layer of zircon was considered.The preparation process of black zircon encapsulated carbon black ceramic pigment by sol-gel-spraying pyrolysis is mixing of zirconium sol,silica sol and carbon ink,then blending the sol into the tube furnace at high temperature by atomizing spray gun.A dense coating layer on carbon black is formed due to the fast transformation from sol into gel by rapid extraction of solvent.The coating layer further densification after calcination.The zircon encapsulated carbon black pigment with high encapsulation ratio is obtained.The CIE coordination of pigment is:L*=21.40,a*=-0.21,b*=-3.31.The pigment looks deep black.TEM images show that the microstructure of encapsulated pigment is that tetragonal ZrO₂disperses in the amorphous silica.This structure helps to the permeation of visible light into the covered layer,and the absorption by carbon black.The preparation of zircon encapsulated carbon black by mesoporous collapse method utilizes the good physical-chemistry action between sol particles with organic template agent which is easy to form the coating layer.The carbon black is formed in-situ by the template after calcination,and then encapsulated by the collapse ZrO₂ mesoporous material.Finally,zircon encapsulated carbon black ceramic pigment is obtained after calcination.In the process of preparation,mesoporous ZrO₂ is firstly prepared,and then silicon sol is added to accelerate the reaction of SiO₂ and ZrO₂ into zircon.In the process,silicon oxide particles permeate into the mesoporous ZrO₂ and cover the ZrO₂ particle.The black ceramic pigment is obtained.After calcined at 900?for 2h in air,the CIE coordination of pigment is L*=24.14,a*=0.06,b*=-1.76.Lower L*value indicates that the pigment has a good encapsulation ratio because the decrease of L*can only origin from the carbon black who had encapsulated.The black ceramic pigment of zircon encapsulated carbon black has good thermal stability.The glaze looks black.It shows a good application prospect.