Ceramics in Aerospace & Defence White Paper

Over the last 20 years the demands of the aerospace and defence sectors on materials have consistently focussed on low density (leading to lightweight components), high specific strength and/or stiffness (maximising the performance of the lightweight materials), and high hardness (for wear resistance and ballistic protection).

Reducing the weight of aerospace components has obvious benefits in terms of increasing the effectiveness of the fuel burned, either in increasing the range or allowing greater payload to be carried for the same amount of fuel. In defence applications, a weight reduction of personal protection (armour/helmet etc) reduces the load on the individual soldier, allowing him to carry more munitions making him more effective, and increasing his agility and maneuverability. Similarly, military vehicles benefit from reduced weight, making them more easily transported (airlifted) into the theatre of operations.

However, these weight reductions must not be achieved at the expense of performance - hence the sector’s drive for new, lightweight, high-performance materials.

In addition to light weighting, there are also specific application areas where a material’s extreme properties allow it to outperform the competition to yield benefits in terms of fuel burn, emissions, payload, and survivability.

On the face of it, ceramic materials, characterised as they are by low toughness and by brittle, often catastrophic failure, should have little attraction for the aerospace and defence sectors, which demand the ultimate in performance and reliability. They are however generally low-density materials offering weight benefits over competing metallic materials.

Moreover, ceramics have high specific strength and stiffness and there are several applications in these sectors where the ‘ceramic option’ has become the norm rather than the exception.

Examples include: personnel and vehicle armour where the material often competes with economically more attractive alternatives but where its improved performance wins out; ultra-high temperature ceramics for applications where no alternative materials exist; and thermal barrier coatings for applications where the temperature of operation exceeds the capability of metallic competitors.