Having thoroughly studied the properties of a large number of glass-ceramic materials, we settled on the so-called cordierite system SiO2-Al2O3-MgO (Fig.2).
The trademark SIAMITE® was chosen based on two considerations: 1) the chemical formulas of the three main components start with Si, A, and M (SiAM); 2) Formica established the production of its material in Thailand, historically known as SIAM. The ending "ite" is commonly used in mineralogy and petrography for many minerals and rocks.
In addition to the three main components mentioned above, the material contains TiO2, ZrO2, ZnO, Li2O as well as some nucleating, fining, and coloring agents. This composition allows obtaining, in the first stage, a homogeneous and color-consistent high-temperature glass, and then crystallizing nanosized (one nanometer is one-billionth of a meter) crystals of zinc spinel – gahnite within it. Alongside spinel, nanocrystals of rutile, zirconium titanate, and others also form. Their presence is determined through X-ray diffraction analysis.
Thus, SIAMITE® is a nanocrystalline glass-ceramic material, comprising nanosized crystals of spinel and other minerals (depending on color), uniformly distributed in the amorphous high-temperature aluminosilicate glass matrix. The size and concentration of nanocrystals affect the degree of transparency of the material and its color. As they increase, the transparent material becomes first, translucent and then opaque.
In the next part, we will discuss the mechanical, optical, and other physical properties of Siamite® and compare them with similar parameters in natural gemstones.