Effect of mineralizers on the synthesis of ceramic pigments from talc

Abstract

The mineralizing effect of sodium fluoride, boric acid, and a natural fluorine-bearing mineral (topaz concentrate) on the synthesis from talc of ceramic pigments with magnesium metasilicate, forsterite, and diopside structures is investigated. It is shown that NaF is the most active mineralizer. It is noted that NaF has a positive effect not only on the synthesis of crystalline structure but also on the chromaticity of the pigments. The pigment compositions developed can be widely used to tint ceramic pastes, glazes and glasses, in the manufacture of building materials, and to make paints.Substances that accelerate phase-formation reactionsmineralizers -are often used to obtain ceramic pigments under industrial and laboratory conditions. The effectiveness of mineralizers depends on their nature, quantity, and degree of dispersion in the reagent being activated [1].The following possibilities for the action of mineralizers are known: protection from resorption of a mineral, creation of artificial rudimentary crystalline grains, action similar to that of a catalyst, formation of solid solutions, and action similar to fluxes.To intensify many reactions in the solid phase, the content of an added mineralizer must be not exceed 1 -3% of the total mass of the mixture. Boron, fluorine, and alkali-metal compounds are used as mineralizers to make ceramic pigments.The mineralizing action of fluorine ions is explained by the fact that they cannot participate in the formation of "bridges" between the silicon-oxygen tetrahedra. When fluorine ions are introduced into the initial mix, the fraction of oxygen atoms which are bound in the space lattice between one another via silicon atoms, changes, i.e., a fluorine ion breaks chemical bonds in a crystal lattice.Boron compounds are often used as mineralizing additions in the synthesis of pigments. It has been observed that B 2 O 3 lowers the sintering temperature of many crystalline materials, since B 3+ has a large charge and a small ionic radius (0.02 nm). Consequently, the polarization power is more strongly expressed for boron than for singly charged alkali-metal ions; B 3+ has a greater effect on decreasing the stability of the crystal lattice. It is also observed that B 2 O 3 has a positive effect on the chromophoric properties of pigments [1].Currently, a promising direction of research is to study the possibility of obtaining ceramic pigments using natural mineral raw materials. The structures of many pigments which are conventionally synthesized from pure oxides and salts of various elements can be obtained from chemically pure natural raw materials, for example, diopside, wollastonite, and others [2]. But, a structural deficiency of natural minerals is their organic capability of incorporating tinting ions. The introduction of mineralizers can loosen their crystal lattice, increase the "ionic capacity" of natural minerals, and improve the color characteristics of ceramic pigments based on natural mineral raw materials [3].We investigated the effect of different mineraliz...

Synthesis and Characterizations of (CoxMg(2−x))SiO4 Forsterite Ceramic Pigments from Mirror Waste

“…The single phase of forsterite structure was obtained when the calcination temperature increased up to 1100 °C. According to data in Table 1 , the second highest elemental concentration of mirror waste was sodium which could play a role in forsterite formation as a similar mineralizer, NaF [ 6 , 7 , 8 , 9 ].…”