Chobham armour
Although the construction details of the Chobham armour remain a secret, it has been described as being composed of ceramic tiles encased within a metal framework and bonded to a backing plate and several elastic layers.
Owing to the extreme hardness of the ceramics used, they offer superior resistance against shaped charges such as high-explosive anti-tank (HEAT) rounds and they shatter kinetic energy penetrators.
The framework holding the ceramics is usually produced in large blocks,[citation needed] giving these tanks, and especially their turrets, a distinctive angled appearance.
Due to the extreme hardness of the ceramics used, the tiles offer superior resistance against a shaped charge jet and they shatter kinetic energy penetrators (KE-penetrators).
The newer composites, though tougher, optimise this effect as tiles made with them have a layered internal structure conducive to it, causing "crack deflection".
Both attack methods will suffer from obstruction to their expected paths, so experience a greater thickness of armour than there is nominally, thus lowering penetration.
The crew remained safe inside for many hours, the Burlington LV2 composite armour protecting them from enemy fire, including multiple rocket-propelled grenades.
Since the early 1990s it has been known that holding the tiles under constant compression by their matrix greatly improves their resistance to kinetic penetrators, which is difficult to achieve when using glues.
Using a number of thinner matrices again enlarges that component for the entire armour package, an effect analogous to the use of alternate layers of high hardness and softer steel, which is typical for the glacis of modern Soviet tanks.
Ceramic tiles draw little or no advantage from sloped armour as they lack sufficient toughness to significantly deflect heavy penetrators.
Indeed, because a single glancing shot could crack many tiles, the placement of the matrix is chosen so as to optimise the chance of a perpendicular hit, a reversal of the previous desired design feature for conventional armour.
A matrix using a titanium alloy is very costly to produce but the metal is favoured for its lightness, strength, and resistance to corrosion, which is a constant problem.
They can also be used as the backing plate for the matrix itself, but this compromises the modularity and thus tactical adaptability of the armour system: ceramic and metal modules can then no longer be replaced independently.
[citation needed] These metal modules function on the principle of perforated armour (typically employing perpendicular rods), with many expansion spaces reducing the weight by up to one third while keeping the protective qualities fairly constant.
[20] The concept of ceramic armour goes back to 1918, when Major Neville Monroe Hopkins discovered that a plate of ballistic steel was much more resistant to penetration if covered with a thin (1–2 millimetres) layer of enamel.
[24] Since the early 1960s there were, in the US, extensive research programmes ongoing aimed at investigating the prospects of employing composite ceramic materials as vehicle armour.
[25] This research mainly focused on the use of an aluminium metal matrix composite reinforced by silicon carbide whiskers, to be produced in the form of large sheets.
[28] An alternative technology developed in the US was based on the use of glass modules to be inserted into the main armour;[27] although this arrangement offered a better shaped charge protection, its multiple hit capability was poor.
A similar system using glass inserts in the main steel armour was from the late fifties researched for the Soviet Obiekt 430 prototype of the T-64;[29] this was later developed into the "Combination K" type, having a ceramic compound mixed with the silicon oxide inserts, which offered about 50% better protection against both shaped charge and KE-penetrator threats, relative to steel armour of the same weight.
After an initial period of speculation in the West as to its true nature, the characteristics of this type were disclosed when the dissolution of the Soviet Union in 1991 and the introduction of a market system forced the Russian industries to find new customers by highlighting its good qualities;[31] it is today rarely referred to as Chobham armour.
[32] In the United Kingdom another line of ceramic armour development had been started in the early 1960s, meant to improve the existing cast turret configuration of the Chieftain that already offered excellent heavy penetrator protection; the research by a team headed by Gilbert Harvey[33] of the Fighting Vehicles Research and Development Establishment (FVRDE), therefore was strongly oriented at optimising the ceramic composite system for defeating shaped charge attack.
[34] The British system consisted of a honeycomb matrix with ceramic tiles backed by ballistic nylon,[35] placed on top of the cast main armour.
[38] Having already designed a system that in their opinion offered satisfactory protection against shaped charges, consisting of multiple-laminate spaced armour with the spaces filled with ceramic polystyrene foam[39] as fitted to the Leopard 1A3, they put a clear emphasis on improving KE-penetrator protection, reworking the system into a perforated metal module armour.
Given the publicly stated protection level for the earliest M1: 350 mm steel equivalence against armour-piercing fin-stabilized discarding sabot (APFSDS) kinetic energy (KE) penetrators, it seems to have been equipped with alumina tiles.
