Development of New Ceramic Dyes

Abstract

Research on new ceramic dyes is addressed to obtain best pigmenting materials in order to reach higher thermal stability (e.g. for porcelainised stoneware) than classical pigments, higher chemical stability towards the coloured matrix or low toxicity in order to satisfy health and environmental requirements. The earlier developments on the research in new ceramic pigments based on new crystal structures (e.g. perovskite, hexaaluminates, fergusonite, pseudobrookite …), new chromophores (e.g. ruthenium, bismuth and rare earth ions), or new methods of preparation are discussed in this communication.

Iron and chromium doped perovskite (CaMO3 M = Ti, Zr) ceramic pigments, effect of mineralizer

“…Ca(Cr x Ti 1Àx )O 3 x = 0.025, 0.05, 0.1 and 0.2 compositions obtained without addition of NH 4 Cl as mineralizer, produce pink color in glazes at low x, but CaCrO 4 crystallizes when x increases, producing pin-hole defects and green colors in glazed samples. The crystallization of chromates can be avoided using NH 4 Cl as mineralizer.…”

“…The crystallization of chromates can be avoided using NH 4 Cl as mineralizer. Only chromium doped calcium titanate produce a complete solid solution in presence of NH 4 Cl: the Ca(Cr x Ti 1Àx )O 3 titanate produces pink color in glazes at low x and dark blue shades at high x. CO samples produce blue colors at low x and at low temperature (1000 8C instead 1200 8C for CE sample).…”

“…When it is characterized as pigment in a CaO-ZnO-SiO 2 conventional transparent glaze used for ceramic tiles (1080 8C) produce the best red-brown color using 0.015 mol/mol of chromium and fired at 1100 8C with a soaking time of 3 h (5% weight added to the transparent glaze show CIEL*a*b* valours of 59.3/12.5/ 9.5). Likewise 5 wt.% addition of NH 4 Cl used as flux agent increase a* and decrease both b* and L* valours (L*a*b* = 45.2/15.3/5.3).…”

“…Perovskite is a ceramic structure that would be added to CPMA list of ceramic pigments [1] because it is well known for its application as ceramic pigment since Eppler [2] developed black pigments from (Sr,Ca)MnO 3 perovskites using oxides and carbonates, mixed with conventional mineralizers fired at 730 8C with soaking time of 3 h. Other perovskites as neodymiates and titanates can be used as ceramic pigments [3,4]. Perovskite ABO 3 is an ideally cubic phase, but really becomes a rhombic syngony ( (4-07-3), several chromium-rutile pigments (Cr,MÁTi)O 2 M = Sb, Nb, W or Mn (11-17-16, 11-18-6, 11-19-6 and 11-46-7), several chromium-spinel pigments A(B,Cr) 2 O 4 (13-29-2, 13-30-3, 13-32-5, 13-33-7, 13-37-713-38-9, 13-40-9, 13-48-7, 13-50-9 and 13-51-7) in chromium case, and hematite brown (3-06-7), iron-chromium spinel brown (13-33-7), iron-titanium spinel brown (13-34-7), iron-nickel spinel brown (13-35-7), iron-zinc spinel brown (13-36-7), iron-zinc-chromium spinel brown (13-37-7), iron-cobalt spinel black (13-39-9), ironcobalt-chromium spinel black (13-40-9), iron-manganese spinel black (13-41-9), iron-manganese-chromium spinel brown (13-48-7), iron-nickel chromium spinel black (13-50-9) and pink koral zircon (14-44-5) for iron.…”

“…338 8C, decomposes) as mineralizer, have been studied. 4 Cl supplied by Panreac S.A., have been used as precursors to 10 g of final product. Nitrates were solved in 200 ml of water and maintaining 70 8C and continuous stirring, titanium isopropoxide was dropped to the solution, and then concentrated ammonia solution was dropped until pH 8 was reached.…”