Papers by Keyword: Red Pigment

Abstract: Mn-doped alumina red pigment was prepared with Mn(NO₃)₂·6H₂O and Al(NO₃)₃·9H₂O as main raw materials by Low-temperature Combustion-Calcination process. The Mn-doped alumina red pigment was tested by XRD, SEM and CIE L*a*b* colour parameter measurement. The results showed that the reaction of Mn(NO₃)₂·6H₂O, Al(NO₃)₃·9H₂O and CH₃COONH₄ with the theoretical ratio could be ignited and self-propagating at 500 °C. One kind pigment with excellent chromatic performance had been gained at the ratio about 1:40 between Mn(NO₃)₂·6H₂O and Al(NO₃)₃·9H₂O. The crystallite of the precursor obtained by Low-temperature Combustion synthesis (LCS) is imperfectly developed and the aggregation of particles is serious. The crystallite of the powder grows up more perfectly after calcined at 1000 °C for 4 hour with a corundum-like structure. The average particle size of the pigment is approximately 5 μm.

Abstract: Double yttrium-aluminium oxide with perovskite structure (YAP) doped with chromium(III) ions seems to be a promising material for red pigments for new ceramic bodies and glazes. The aim of the present paper was to examine the influence of the precursors morphology on colour properties of the YAP pigments. Two kinds of aluminium hydroxide powders were used, fine- and coarse-grained. The fine Al(OH)3 powder was amorphous with D50=4.58 µm and the coarse one was crystalline gibbsite with D50=42.4 µm. It was stated that using of aluminium hydroxide powders of different morphology led to substantial differences in phase composition of the final materials. Using coarse-grained aluminium hydroxide powder caused formation of over 95 wt% of YAP phase whereas the pigments prepared with amorphous aluminium hydroxide contain significant amounts of other phases in the Y2O3-Al2O3 system. The differences in phase compositions resulted in differences in colour properties of the pigments.

Abstract: Tantalum nitride (Ta3N5) is a nontoxic red pigment that is being developed as a substitute for Cd-related pigments Ta3N5 is produced by the nitridation and heat treatment of amorphous Tantalum precursors. Doping elements were added in the precursor manufacturing stage to improve the red color tone of tantalum nitride. Grain growth was observed in nitrides that formed second phases, such growth led to an increase in the average grain size comprared to undoped nitrides, and the colors declined as the oxygen content increased. Nitrides that did not form second phases in response to doping elements remained a single-phase Ta3N5 and exhibited an excellent red color with a high nitrogen content. We determined that a change in the oxygen/nitrogen contents affected the color manifestation, which depended on the amount by which doping was increased.