Effect of ZrSiO4ZnO Ratio on the Properties of Opaque Glazes

A ceramic raw glaze can be prepared from
a mixture of specified raw materials such as
alumina, kaolin, wollastonite, silica, feldspar,
calcite, talc, dolomite, zinc oxide 1., stannic
oxide, zirconia and zircon 2.; after being ground
and applied onto a ceramic body. This mixture
transforms either wholly or partially into a
vitrified coat during a firing process 3.. Glazes
are used to provide waterproofing protection
to bodies, increase the mechanical durability,
chemical inertness, abrasion and scratch
resistance 4, 5.. They are also appreciated for
their aesthetic aspects 6. (color, transparency,
opacity, glossiness, smoothness, whiteness,
etc.). In general, a highly opaque glaze is
favorable for sanitary-ware products. The glaze
opacity is obtained by the interaction between
the crystalline phase that is dispersed in the
glassy matrix and the incident light, resulting in
the reflection and dispersion of the light. Thus,
the greater the difference between the refractive
indexes of the opacifier and the glassy matrix,
the higher the opacity 7