Transparent components with almost thickness independent high transmission at UV, visible and IR wavelengths are made from commercial powders and, optionally, by new syntheses.
Because of birefringence the transmission of 1 mm thin ceramics with non-cubic crystal structure (e.g. corundum - α-Al2O3) hardly exceeds 80 % of the theoretical maximum, and their transparency is rather sensitive to thickness. On the contrary, cubic Mg-Al spinel can become fully transparent even with a centimeter of thickness if last hundredths of porosity percents are eliminated. Commonly, this is achieved by sintering at high temperatures > 1700 °C which results in very coarse grain sizes and reduced mechanical parameters. The new fine-grained grades from IKTS (Fig. 1) avoid such shortcomings.
- Real in-line transmission (RIT) > 80 % which is 0.95 of the theoretical maximum (measured at λ = 640 nm with aperture 0.57° at 5 mm thickness). Low dependence of transmission on thickness (Fig. 2)
- High transmission from ultraviolet through infrared (Fig. 3)
- High hardness (HV10 ~ 15 GPa) by small grain sizes down to the sub-µm range. As a consequence, the ballistic strength (AP ammunition) comes close to sub-µm Al2O3 armor and outperforms even sapphire
Products and services offered
- Powder technology for highly transparent spinell ceramics with high hardness starting from commercial spinel powders
- Technological options: reactive sintering, new chemical synthesis
- Technological investigations for upscaling supporting the development of new products
- Investigations of the technical performance in various applications