Study On Synthesis And Properties Of Copper Silicate System Pigments

Copper silicate system pigments are highly stable decoration materials.Nowadays they have been widely concerned by people because of the better fluorescence performances.Although the solid state process required higher calcination temperature and the morphology of the products are difficult to control.As for the sole hydrothermal method,it still required higher hydrothermal temperature and longer hydrothermal time.These system pigments could not be extensively used in industrial fields due to the preparation limitation.Therefore,an efficient and effective synthetic method is the way of realizing their wide industrial application.Chinese purple?Ba Cu Si₂O₆?,Egyptian blue(Ca Cu Si₄O_{1 0}),Chinese blue(Ba Cu Si₄O_{1 0})and Chinese dark blue?Ba Cu₂Si₂O₇?occupy a large proportion of research in the copper silicate system pigments,they also possess good luminescence properties.Therefore,these pigments were selected as the research objects of this paper.In this work,the coprecipitation and hydrothermal proc ess combined with final crystallization calcination was used to prepare these pigments,which effectively reduced the reaction temperature and shortened the reaction time.The crystal structure,morphology and color characteristics of the obtained samples were examined by XRD,colorimetric analysis and other techniques.The effects of calcination temperature,calcination time,hydrothermal time,different silicate raw materials and the solution p H value on the structure and color characteristics were investigated.?1?Sodium silicate?Na₂Si O₃?and sodium metasilicate?M=2.1².2,soluble glass?as silicon source,copper nitrate as copper source and barium nitrate as barium source,the Chinese purple was prepared by the coprecipitation and hydrothermal process,and then sintered at certain temperatures.The effects of calcination temperature,calcination time,hydrothermal time and different silicon raw materials on the structure and color characteristics of the Chinese purple were investigated.The results showed that the suitable synthetic conditions of the Chinese purple were optimized as hydrothermal reaction temperature of 180?for 20 h and calcination temperature of 700?for 5 h with the sodium silicate as silicon raw material.The corresponding color characteristics of the L*value,a*value,b*value and c*value are 60.8,10.91,-45.58and 46.87 respectively,while the chromaticity coordinates are x=0.22305 and y=0.21299.In addition,the as-prepared Ba Cu Si₂O₆pigment also shows well optical property with broadband absorption in the 500-800 nm range,and the super emission in the 800-1200 nm range in which the emission peak is centered on 916 nm.?2?Sodium silicate and sodium metasilicate as silicon source,copper nitrate as copper source and calcium nitrate as calcium source,the Egyptian blue was prepared by the coprecipitation and hydrothermal process,and then sintered at certain temperatures.The effects of calcination temperature,calcination time,hydrothermal time,different silicon raw materials and the solution p H value on the structure and color characteristics of the Egyptian blue were investigated.The results showed that the suitable synthetic conditions of the Egyptian blue were optimized as hydrothermal reaction temperature of 180?for 24 h and calcination temperature of 800?for 5 h,with the sodium silicate as silicon raw material and the solution p H value as 9.5-10.The corresponding color characteristics of the L*value,b*value and c*value are 61.23,-23.57 and 24.93 respectively,while the chromaticity coordinates are x=0.23277 and y=0.26737.In addition,the as-prepared Ca Cu Si₄O_{1 0} pigment also shows well optical property with broadband absorption in the 500-800 nm range,and the super emission in the800-1200 nm range in which the emission peak is centered on 953 nm.?3?Sodium silicate and sodium metasilicate as silicon source,copper nitrate as copper source and barium nitrate as barium source,the Chinese blue was prepared by the coprecipitation and hydrothermal process,and then sintered at certain temperatures.The effects of calcination temperature,calcination time,hydrothermal time,different silicon raw materials and the solution p H value on the structure and color characteristics of the Chinese blue were investigated.The results showed that the suitable synthetic conditions of the Chinese blue were optimized as hydrothermal reaction temperature of 180?for 20 h and calcination temperature of 800?for 5 h,with the sodium silicate as silicon raw material and the solution p H value as 11.5-12.The corresponding color characteristics of the L*value,b*value and c*value are 63.75,-44.56 and 44.57 respectively,while the chromaticity coordinates are x=0.2152 and y=0.2248.In addition,the as-prepared Ba Cu Si₄O_{1 0} pigment also shows well optical property with broadband absorption in the 500-800 nm range,and the super emission in the800-1200 nm range in which the emission peak is centered on 980 nm.?4?Sodium silicate and sodium metasilicate as silicon source,copper nitrate as copper source and barium nitrate as barium source,the Chinese dark blue was prepared by the coprecipitation and hydrothermal process,and then sintered at certain temperatures.The effects of calcination temperature,calcination time,hydrothermal time and different silicon raw materials on the structure and color characteristics of the Chinese dark blue were investigated.The results showed that the suitable synthetic conditions of the Chinese dark blue were optimized as hydrothermal reaction temperature of 180?for 20 h and calcination temperature of 800?for 5 h with the sodium silicate as silicon raw material.The corresponding color characteristics of the L*value,b*value and c*value are 39.08,-17.65 and 18.49 respectively,while the chromaticity coordinates are x=0.24059 and y=0.27213.