ultra low porosity ceramics

The secret of transparent ceramic is its extremely low porosity.

Ceramic consists of many billions of tiny crystals that are connected to one another by high temperatures of 1200-1800°C. After the ceramic is fired, a few pores remain between the crystals. Normal densely sintered technical oxide ceramics have about 1-2% porosity. In contrast to tableware, these ceramics are waterproof even without glaze and have much higher strength and hardness. However, ceramic remains a brittle material and the remaining pores or defects can reduce the strength. 

The new transparent ceramic sintered almost pore-free not only has a higher strength but can also become transparent. Using a Mie simulation calculation, the graphic shows the light scattering from pores of different sizes in spinel ceramics 1 mm thick. Due to the scattering of light on pores, normal technical ceramic appears white. With an extremely low porosity of 0.01% the ceramic becomes transparent.

The manufacture of transparent ceramics requires special high-purity raw materials and new processing techniques. Transparent ceramic does not contain any glass that could close the pores, but is created through the complete compression of high-purity synthetic oxide powder.