Composite armour Composite armour is a type of vehicle armour consisting of layers of different material such as metals , plastics , ceramic s or air . Most composite armours are lighter than their all - metal equivalent , but instead occupy a larger volume for the same resistance to penetration . It is possible to design composite armour stronger , lighter and less voluminous than traditional armour , but the cost is often prohibitively high , restricting its use to especially vulnerable parts of a vehicle . Its primary purpose is to help defeat high explosive anti - tank ( HEAT ) rounds . HEAT had posed a serious threat to armoured vehicles since its introduction in World War II . Lightweight and small , HEAT rounds could nevertheless penetrate hundreds of millimetres of the hardest steel armours . The capability of most materials for defeating HEAT follows the " density law " , which states that the penetration of shaped charge jets is proportional to the square root of the shaped charge liner density ( typically copper ) divided by the square root of the target density . On a weight basis , lighter targets are more advantageous than heavier targets , but using large quantities of lightweight materials has obvious disadvantages in terms of mechanical layout . Certain materials have a sweet spot in terms of density that makes them particularly useful in this role . History . The earliest known composite armour for armoured vehicles was developed as part of the US Army ' s T95 experimental series from the mid - 1950s . The T95 featured " siliceous - cored armor " which contained a plate of fused silica glass between rolled steel plates . The stopping power of glass exceeds that of steel armour on a thickness basis and in many cases glass is more than twice as effective as steel on a thickness basis . Although the T95 never entered production , a number of its concepts were used on the M60 Patton , and during the development stage ( as the XM60 ) the siliceous - cored armour was at least considered for use , although it was not a feature of the production vehicles . The first widespread use of a composite armour appears to have been on the Soviet T - 64 . It used an armour known as Combination K , which apparently is glass - reinforced plastic sandwiched between inner and outer steel layers . Through a mechanism called thixotropy , the resin changes to a fluid under constant pressure , allowing the armour to be moulded into curved shapes . Later models of the T - 64 , along with newer designs , used a boron carbide - filled resin aggregate for greatly improved protection . The Soviets also invested heavily in reactive armour , which allowed them some ability to control quality , even after production . The most common type of composite armour today is Chobham armour , first developed and used by the British in the experimental FV 4211 tank , which was based on Chieftain tank components . Chobham sandwiches a layer of ceramic between two plates of steel armour , which was shown to dramatically increase the resistance to HEAT rounds , even in comparison to other composite armour designs . Chobham was such an improvement that it was soon used on the new U . S . M1 Abrams main battle tank ( MBT ) as well . It is the fabrication of the ceramic in large tiles that gives the Challenger and Abrams their " slab sided " look . Design . Chobham ' s precise mechanism for defeating HEAT was uncovered in the 1980s . High speed photography showed that the ceramic material as the HEAT round penetrates , the highly energetic fragments destroying the geometry of the metal jet generated by the hollow shaped charge , greatly diminishing the penetration . The effectiveness of the system was amply demonstrated in Desert Storm , where not a single British Army Challenger tank was lost to enemy tank fire . However , one was destroyed by friendly fire on March 25 , 2003 killing two crew members after a HESH round detonated on the commander ' s hatch causing high velocity fragments to enter the turret . Chobham - type armour is currently in its third generation and is used on modern western tanks such as the British Challenger 2 and the American M1 Abrams . Usage . The French Leclerc , Indian Arjun , Pakistan Al - Khalid tank and Chinese Type 96 / 98 and Type 99 tanks use modular composite armour . The adoption of Modular composite armour design facilitated upgrading and exchange of the armour . Soviet / Russian T - 80 Us and the Pakistani Al - Khalid use composite armour in tandem with explosive reactive armour ( ERA ) , making it hard for missiles and tank rounds to penetrate the frontal and a portion of their side armour . Composite armour has since been applied to smaller vehicles , right down to jeep - sized . Many of these systems are applied as upgrades to existing armour , which makes them difficult to place around the entire vehicle . Nevertheless they are often surprisingly effective ; ceramic upgrades to Canadian M - 113 s were carried out in the 1990s , after it was realized that it would offer more protection than newly built APCs like the M2 Bradley . Improvised . In 2004 , Marvin Heemeyer used an " ad hoc " composite armour on his Komatsu D355A bulldozer ( " Killdozer " ) used in a rampage in response to a dispute with the city he lived in over a zoning issue . The armour , at some places a foot thick , consisted of a layer of concrete sandwiched between layers of steel , successfully rendering the vehicle impervious against small arms fire and small explosives .