Synthesis and study of low-temperature ferrum-willemite ceramic pigments

Abstract

The synthesis of ferrum-willemite ceramic pigments in the system xFeO(2-x)ZnOSiO 2 (where x=0.125-1.00) was investigated in this work. The results of colorimetric measurements (in the system CIEL * a * b *) showed that the concentration of iron(II) oxide in the composition of 0.25 mol is sufficient for preparation of ceramic pigments of redbrown color. An increase in the content of iron(II) oxide in the composition of ceramic pigments from 0.125 to 0.25 mol causes the growth of values of color coordinates à * (up to +26.68) and b * (up to +36.73) as well as lightness L * (up to 48.51). A further increase in the concentration of FeO in pigments to 1.0 mol results in a decrease in the amount of red color: the value of red color coordinate à * falls to +21,87. An effective role of hydrate of silicon(IV) oxide introduced as a quartz-containing component of experimental pigments is also shown. It allows reducing the temperature of their synthesis to 900-1000 0 Ñ. Moreover, the growth of the firing temperature from 900 to 1000 0 Ñ leads to a slight increase in the amount of red color of the developed red-brown pigments (value of color coordinate à * increases from +25.38 to +26.68). By means of the methods of X-ray phase analysis and electron paramagnetic resonance, it was found that willemite solid solution and spinel (zinc ferrite) act as a carrier of color in these ceramic pigments. Formation of the above crystal phases is completed already at the firing temperature of 1000 0 Ñ. The synthesized pigments can be successfully used for coloring of glaze coatings on ceramics as well as glass-enamel coatings for metals.