NATO SPS project develops thinner, lighter transparent armour windows

The new armoured window, which was developed as part of a Science for Peace and Security (SPS) project, will be used to make armoured glass windows for military and security personnel vehicles. It reached the STANAG 4569 Level III (protection against 7,62 armour piercing bullets, e.g. from sniper rifles) certificate – currently the highest level of protection with transparent armour – and can now be produced commercially for special vehicles (commando vehicles, transportation of officers on the battlefield).

Compared with opaque armour materials, the area of transparent armoured applications are limited due to very much higher thickness and weight for the same ballistic results. The effectiveness of new types of small calibre armour-piercing ammunition is now so high that the minimum thickness of armoured glass available on the market that is able to withstand the multihit impact is 85–105 mm (made from layers of float glass and polycarbonates).

In the framework of the SPS project, scientific teams from the Czech Republic, Slovak Republic, Russia and Ukraine have worked together with the French glass-manufacturing company Saint-Gobain Sully in developing a new sapphire-based armour allowing armoured windows to be about 40% thinner, lighter than a standard glass solution – at a reasonable cost compared with the currently used glass windows. The window unit consists of back multi layered transparent armour system (composed with sapphire strip layer) and front steel armour louver with movable lamellas.

During the demonstration in Slavicin, bullets were shot at samples of the prototype unit showing that the thinner material is as strong as the old thick glass. Besides the obvious advantages for mobility of lighter windows, the reduced thickness also allows soldiers and security personnel to have a less distorted view and a higher light transmission .

The teams from Ukraine and Slovak Republic produce the materials for the front layers of sapphire single crystals The Czech team at Turnov (Saint-Gobain Advanced Ceramics) is producing samples of the end-result by using a sandwich-layer method and is evaluating the properties in a shooting laboratory in Slavicin. In addition, the Russian team from St. Petersburg performs preliminary ballistic tests looking at the impact of high-hardness high-speed projectiles on these samples.

The project is funded by the NATO Science for Peace and Security Programme (www.nato.int/science).