The use of ceramic plates dates back to 1918, after the end of world War I, when Colonel Newell Monroe Hopkins discovered that coating steel armor with a ceramic glaze would greatly enhance its protection.
Although the properties of ceramic materials were discovered early, it was not long before they were used for military purposes.
The first countries to widely use ceramic armor were the Former Soviet Union, and the U.S. military used it extensively during the Vietnam War, but ceramic armor only emerged as personal protective equipment in recent years due to early cost and technical problems.
In fact, alumina ceramic was used in body armor in the UK in 1980, and the US army mass-produced the first truly “plug-in board” SAPI in the 1990s, which was a revolutionary protective equipment at that time. Its NIJIII protection standard could intercept most bullets that could threaten the infantry, but the US army was still not satisfied with this. ESAPI was born.
ESAPI
At the time, ESAPI’s protection was not too much of a hack, and the NIJIV level of protection made it stand out and saved the lives of countless soldiers. How it does that is probably not a lot of attention.
To understand how ESAPI works, we need to understand its structure first. Most composite ceramic armor is a structural ceramic target + metal/non-metal back target, and the US military ESAPI also uses this structure.
Instead of using silicon carbide ceramic that works and is “economical”, the US Army used the more expensive boron carbide ceramic for ESAPI. On the backplane, the US army used UHMW-PE, which was also extremely expensive at the time. The price of the early UHMW-PE even exceeded that of the BORON carbide.
Note: because of the different batch and process, kevlar may also be used as a backing plate by the US army.
Types of bulletproof ceramics:
Bulletproof ceramics, also known as structural ceramics, have high hardness, high modulus characteristics, usually used for metal abrasion, such as grinding ceramic balls, ceramic milling tool head……. In composite armor, ceramics often play the role of “warhead destruction”. There are many kinds of ceramic in body armor, the most commonly used are alumina ceramics (AI²O³), silicon carbide ceramics (SiC), boron carbide ceramics (B4C).
Their respective characteristics are:
Alumina ceramics have the highest density, but the hardness is relatively low, the processing threshold is lower, the price is cheaper. The industry has different purity is divided into -85/90/95/99 alumina ceramics, its label is higher purity, hardness and price are higher
Silicon carbide density is moderate, the same hardness is relatively moderate, belongs to the structure of cost-effective ceramics, so most domestic body armor inserts will use silicon carbide ceramics.
Boron carbide ceramics in these kinds of ceramics in the lowest density, the highest strength, and its processing technology is also very high requirements, high temperature and high pressure sintering, so its price is also the most expensive ceramics.
Taking NIJ grade ⅲ plate as an example, although the weight of alumina ceramic insert plate is 200g~300g more than silicon carbide ceramic insert plate, and 400g~500g more than boron carbide ceramic insert plate. But the price is 1/2 of silicon carbide ceramic insert plate and 1/6 of boron carbide ceramic insert plate, so the alumina ceramic insert plate has the highest cost performance and belongs to the market leading products
Compared with metal bulletproof plate, composite/ceramic bulletproof plate has an insurmountable advantage!
First of all, the metal armor hits the homogeneous metal armor by the projectile. Near the limit penetration velocity, the failure mode of the target plate is mainly compression craters and shear slugs, and the kinetic energy consumption mainly depends on the shear work caused by plastic deformation and slugs.
The energy consumption efficiency of ceramic composite armor is obviously higher than that of homogeneous metal armor.
The reaction of ceramic target is divided into five processes
1: the bullet roof is broken into small pieces, and the crushing of the warhead increases the target action area, so as to disperse the load on the ceramic plate.
2: cracks appear on the surface of the ceramics in the impact zone, and extend outwards from the impact zone.
3: The force field with the impact zone compression wave front into the interior of the ceramic, so that the ceramic broken, the powder generated from the impact zone around the projectile flying out.
4: cracks on the back of the ceramic, in addition to some radial cracks, cracks distributed into a cone, damage will occur in the cone.
5: the ceramic in the cone is broken into fragments under complex stress conditions, when the projectile impact ceramic surface, most of the kinetic energy is consumed in the destruction of the cone’s round bottom area, its diameter depends on the mechanical properties and geometric dimensions of the projectile and ceramic material.
The above is just the response characteristics of ceramic armor at low/medium speed projectiles. Namely, the response characteristics of projectile velocity ≤V50. When the projectile velocity is higher than V50, the projectile and ceramic erode each other, creating a mescall crush zone where both armor and projectile body appear as fluid.
The impact received by the backplane is very complex, and the process is three-dimensional in nature, with interactions between single layers and across these adjacent fiber layers.
In simple terms, the stress wave from the fabric wave to the resin matrix and then to the adjacent layer, the strain wave reaction to the fiber intersection, resulting in the dispersion of impact energy, wave propagation in the resin matrix, the separation of the fabric layer and the migration of the fabric layer increase the ability of the composite to absorb kinetic energy. The migration caused by crack travel and propagation and the separation of individual fabric layers can absorb a large amount of impact energy.
For the penetration resistance simulation experiment of composite ceramic armor, the simulation experiment is generally adopted in the laboratory, that is, the gas gun is used to carry out the penetration experiment.
Why has Linry Armor had a price advantage as a manufacturer of bulletproof inserts in recent years? There are two main factors:
(1) Due to engineering needs, there is a great demand for structural ceramics, so the price of structural ceramics is very low [cost sharing].
(2) As a manufacturer raw materials and finished products are processed in our own factories, so that we can provide the best quality products and the most friendly prices for bulletproof shops and individuals.
Post time: Nov-18-2021