Since the early 1960s, cast or welded steel armour have been supplemented by «composite», «advanced», «laminated», or «special» armours. This trend started with the Russian T-64. It used cast and welded steel armour which incorporated “Combination K” – a mixture of steel and ceramic inserts intended to bar the way to Heat (high explosive anti-tank) warheads. Ceramic materials first seemed an odd choice, but in practice proved better than steel at resisting the effects of shaped-charge jets. Since they are brittle, ceramics need to be combined with steel or even aluminium to form multilayered armour. Although much thicker than steel armour, these multilayer systems give high levels of protection. The turret front on the T-64 had a level of protection equivalent to 410 millimetres of steel, 70 per cent better than was provided by the steel armour of the T-62 turret.

Subsequent Soviet-era tanks refined the art even further. The sloped glacis of the T-72 incorporated a 200-millimetre thick laminate armour, thought to be the equivalent of 500 to 600 millimetres of steel, and later production examples had advanced armour turrets. The design finally evolved into the T-90 series protected by what the Russians describe as “combined armour plus Kontakt-5 explosive reactive armour (Era)”. The T-80B, for its part, has a laminate glacis, and a turret protected by a new-generation composite armour equivalent to 500 millimetres of steel. The Ukrainian T-84 derivative makes extensive use of Era, and has a new Ukrainian-designed turret with multilayer armour designed to resist APFSDS (armour piercing fin stabilised discarding sabot) and Heat attacks.

Announced on 17 June 1976, Britain’s Chobham was described by the then Secretary of State for Defence as being the most significant achievement in tank design since the Second World War. Tested in 1971 on the experimental FV4211, its first application would have been the FV4030/3 Shir 2 derivative of the Chieftain which was being developed for Iran in the late 1970s (but cancelled in 1979). The prototypes formed the basis of the Chobham-armoured Challenger I. The Challenger 2 uses what is described simply as “advanced armour technology”, thought to be a second-generation development of Chobham armour. An armour similar to Chobham is used in the hull and turret of the M1 Abrams, and other forms of advanced armour have been adopted in tanks designed by China, France, Germany, India, Israel, South Korea, Pakistan, Poland, Romania, and South Africa. In some cases such as South Korea, the special armour was obtained from abroad; some nations may have copied or modified foreign armours, but in other cases the technology is indigenous. While details of modern composite armours such as Chobham remain classified, most seem to rely on layers of various materials. A recent Russian paper commented that a layer of depleted uranium was an effective counter to KE (kinetic energy) projectiles, and suggested that in future tanks the steel base armour under the multiple layers could be reinforced with carbon fibres.

Although ceramic materials have been used in layered composite armours, their usefulness in add-on armours may be limited. Research into possible add-on protection systems carried out by Sweden’s Consortium of Armour Ceramics has shown that ceramics are only cost and weight efficient in systems designed to protect against small-calibre KE rounds. “On main battle tanks, ceramic armour is not regarded as providing general protection, but may be used to protect limited areas where cost is less important,” a 1995 report concluded.

The Merkava Mk 2 was the first Israeli main battle tank to be fitted with advanced armour: on the hull front, on the front and sides of the turret, and behind the steel skirts. For the later Mk 3, IMI opted to fit more than half of the vehicle’s protection in the form of replaceable bolt-on panels which permit the easy repair of battle damage, and allow the vehicle to be given the increased protection made possible by later armour development. The Merkava Mk 3 was the first tank to have most of its “special armour” in modular form, although the Leclerc had a similar approach with hull and turret made from welded steel with protection by modular composite armour that can easily be replaced or upgraded. Modular armour is also found on China’s Type 90-II main battle tank, and can be expected on future Russian tanks. The Leopard 2 uses a spaced multilayer armour, while the Leopard 2 Improved has a redesigned turret with the addition of externally mounted modules of third-generation armour on the front, sides and roof claimed to resist all known kinetic and chemical energy threats. To save weight and cost, this additional protection was not added to the turret roof, but a spall liner was fitted to the turret interior. Additional armour has been added to the nose, glacis and sides to improve protection over the frontal arc. The 120 Hägglunds-built Leopard 2 (S) hulls incorporate a passive armour developed by Åkers of Sweden.

Whether fitted as an add-on or installed as an integral part of a vehicle’s protection, explosive reactive armour has played a growing role over the last two decades This trend seems set to continue. Several recent designs, including the T-90S and T-84 have integral reactive armour. Since tandem Heat warheads are now being widely marketed as a counter to Era and other advanced armours, tandem Era layers are an obvious countermeasure.