Bulletproof glass, also known as ballistic glass or bullet-resistant glass, is an incredibly strong type of glass that is designed to withstand ballistic impacts from projectiles such as bullets. It is composed of layers of glass and plastic that are laminated together under high pressure and heat. The purpose of bulletproof glass is to provide protection against gunfire for important structures and vehicles.
While bulletproof glass is very strong, it is not completely impenetrable. With enough firepower or the right ammunition, any bulletproof glass can be defeated. This raises the natural question: What materials are even stronger than bulletproof glass? Keep reading to find out what substances can surpass the strength of bulletproof glass and provide the ultimate protection.
What Makes Bulletproof Glass So Strong?
Before examining what is stronger, it helps to understand what gives bulletproof glass its tremendous durability in the first place. There are two main factors that contribute to the strength of bulletproof glass:
Laminated Layers
Bulletproof glass consists of layers of glass and plastic laminated together under extremely high pressure. The core of bulletproof glass is often made of polycarbonate or acrylic layers that provide flexibility. This sandwiches between plates of ordinary glass.
The glass layers allow the material to break like normal upon impact while retaining its structure. The polymer core absorbs and dissipates the energy from the projectile, preventing it from fully penetrating the glass. The thickness and number of laminated layers directly contribute to the ballistic rating and strength of the glass.
Rigidity
Bulletproof glass needs to be extremely rigid to prevent bending or warping when struck by a bullet. Flexibility allows the material to withstand impacts without shattering, but it also needs to be hard enough to stop projectiles in their tracks.
The laminated layers are compressed together under heat and over 100psi of pressure. This solidifies the glass and plastic sheets together into a single rigid ply with formidable strength. The rigidity provides the resistance needed to decelerate bullets and absorb their kinetic energy.
What Can Penetrate Bulletproof Glass?
Now that we understand why bulletproof glass is so strong, what types of items or forces can actually pierce or damage it? Here are some examples:
Armor-Piercing Bullets
While standard ammunition will not penetrate true bulletproof glass, armor-piercing rounds are specifically designed to defeat ballistic armor. Their hard metal cores and pointed tips allow them to tunnel through the layers of glass rather than flattening on impact. Level III and IV bullet-resistant glass provides some protection, but no bulletproof glass can completely stop heavy armor-piercing rifle rounds.
High-Powered Rifles
Extremely high-velocity rifles like .50 caliber sniper rifles can generate enough concentrated force to penetrate even thick bulletproof glass. Their heavy bullets also retain their shape and pointed tips better than standard rounds. While bulletproof glass can stop intermediate rifle rounds, it cannot withstand repeated hits from the most powerful anti-materiel and anti-armor rifles.
Explosives
A sufficiently large blast can shatter any bulletproof glass. While the glass may remain somewhat intact due to the plastic laminate layers, the shock waves and pressure from an explosion will compromise its structure. Shaped charges from rockets and grenades that focus explosive force into a small point are especially effective at piercing bulletproof defenses.
Thermite Lances
Thermite lances burn at over 4,000°F when ignited and can melt through most materials including bulletproof glass. The intense heat softens the laminate layers, allowing the lance to slowly cut an opening. However, thermite lances require time to penetrate obstacles and do not work instantly like explosive charges.
Laser Cutting
Industrial laser cutters output concentrated beams that can burn through glass, plastics, and even metals. When focused on a small point, a powerful cutting laser can gradually melt a hole in bulletproof glass by slicing through the laminate layers one by one. Like thermite lances, laser cutting is a slow process and does not work as quickly as explosives. However, it allows extremely precise and controlled penetration.
What Materials Are Stronger Than Bulletproof Glass?
We have established that while very durable and protective, bulletproof glass has its limitations and can be defeated under the right circumstances. This brings us back to the original question – what materials are even stronger than bulletproof glass and can provide protection where it fails? Here are some of the strongest and most impenetrable materials that exceed the strength of any bulletproof glass:
Graphene
Graphene is an astounding material made of a single layer of carbon atoms arranged in a hexagonal lattice. Despite being incredibly thin, graphene is over 200 times stronger than steel by weight, lighter than aluminum, and almost perfectly transparent. It is ultra-light and can be layered to absorb impacts. Graphene dissipates force much better than the plastic lamination used in bulletproof glass, making it effective at stopping projectiles and explosions. It has even been shown to withstand a direct shot from a .50 cal sniper rifle.
Carbon Nanotubes
Carbon nanotubes are effectively tiny cylindrical tubes made of graphene. Their small size and immense tensile strength allow carbon nanotubes to be woven into fabrics or added to composite materials. The properties of carbon nanotubes can potentially enhance the ballistic performance of body armor, vehicle armor, and structural shielding past the limits of bulletproof glass laminates.
Aluminum Oxynitride
Also known by the trade name ALON, transparent aluminum oxynitride ceramic possesses incredible strength and optical clarity. It is made of aluminum, oxygen, and nitrogen bonded together. At a third of the weight of glass and bulletproof glass, ALON is durable enough to protect against multiple armor-piercing rounds. It does not splinter or crack under impact either. ALON has seen use in ballistic armor and bulletproof transparent panels.
Dyneema® Fibers
Dyneema® from DSM is an ultra high molecular weight polyethylene fiber 15 times stronger than steel by weight. Lighter than glass yet highly resistant to chemicals, water, UV radiation, and dirt, Dyneema® fibers have been incorporated into protective materials that are lighter weight and more flexible than bulletproof glass. Dyneema® offers one of the highest strength-to-weight ratios of any fiber suitable for ballistic applications.
Spider Silk
Spider silk is a natural protein fiber produced by spiders to make webs and cocoons. Gram for gram, certain spider silks can be stronger and more elastic than Kevlar, steel, and other industrial fibers. Spider silk does not lose strength when made intothread and woven into textiles. Researchers are studying how to replicate spider silk for use in incredibly strong and flexible fabrics for body armor, parachutes, artificial tendons, and other products.
Boron Carbide Ceramics
Boron carbide ceramics made of boron and carbon are extremely hard materials used in bulletproof vests, protective armor plates, and ballistic glass laminates. They are lighter than steel while several times stiffer and stronger. The material does not break upon high velocity impact either. Boron carbide ceramics prove more effective than aluminium oxynitride at stopping armor piercing ammunition. However, they are more expensive and opaque rather than transparent.
Spectra® Fibers
Spectra® ultra high molecular weight polyethylene fibers are strands of very long polyethylene molecules produced by Honeywell. Spectra® fibers demonstrate greater strength and stiffness than aramid fibers like Kevlar. Their lightweight, flexibility, and damage resistance make Spectra® fibers well-suited for ballistic textiles and composite laminates stronger and lighter than standard bulletproof glass.
Depleted Uranium
Military armor often uses depleted uranium alloy plates for the deepest possible protection. Depleted uranium is extremely dense and capable of withstanding high temperatures. It exhibits ballistic properties superior to traditional steel and titanium armors as well as bulletproof glass laminates. Depleted uranium alloys shatter incoming projectiles on impact. However, uranium poses health hazards and is not suitable for mainstream applications.
Graphene Polymer Composites
As mentioned earlier, graphene possesses tremendous strength on its own. Researchers have also developed promising composite materials that incorporate graphene with polymers like polyvinyl alcohol. These graphene polymer composites can be lighter, thinner, more flexible, and higher-performing than Kevlar fabrics and bulletproof glass laminates when engineered properly.
How Are These Strong Materials Used?
We have now highlighted materials capable of exceeding the protective qualities of even the strongest bulletproof glass. Here are some examples of how these supremely strong substances are being utilized:
Vehicle and Aircraft Armor
Military vehicles and aircraft use graphene sheets, composites reinforced with carbon nanotubes and Dyneema® fibers, spider silk wovens, boron carbide ceramic plates, and depleted uranium alloy armor for superior ballistic protection compared to conventional bulletproof glass. However, exotic armor solutions are expensive and not practical for everyday commercial or law enforcement vehicles.
Body Armor
Ballistic vests and helmets crafted using ultra strong polyethylene fibers, aramids, and partly spider silk fabrics provide protective capabilities beyond those of rigid bulletproof glass. New material technologies will help make body armor lighter, thinner, more comfortable, and more effective.
Structural Shielding
Panels made using aluminum oxynitride, boron carbide ceramics, and graphene-enhanced composites can furnish structural transparency and resistance to penetration that standard bulletproof glass cannot match. This allows buildings to incorporate ballistic protection without losing visibility. Such materials also suit mobile shields carried by law enforcement and the military.
Transparent Armor
For transparent armor needs that exceed the limits of bulletproof glass, aluminum oxynitride and graphene offer two futuristic materials that are highly bullet resistant in addition to being see-through. Their combination of optical clarity and ballistic strength surpasses any bulletproof glass currently available. However, costs are extremely prohibitive for widespread adoption.
Electronic Displays
The unparalleled thinness, strength, and transparency of graphene may one day revolutionize mobile device displays and televisions. Graphene-based OLED displays could be flexible, durable, and suitable for roll-up or foldable devices well beyond the capabilities of Gorilla Glass. But graphene remains restricted to R&D labs with no commercial products in market yet.
Comparison to Bulletproof Glass
Here is a comparison table highlighting the properties and performance of bulletproof glass versus the ultra-strong materials discussed above:
| Material | Strength | Weight | Transparency | Ballistic Protection Level |
|---|---|---|---|---|
| Bulletproof Glass | Strong | Heavy | Transparent | Up to Level III/III+ |
| Graphene | Extremely Strong | Very Light | Transparent | Up to Level IV |
| Carbon Nanotubes | Extremely Strong | Very Light | Not Transparent | Up to Level IV |
| Aluminum Oxynitride | Very Strong | Lightweight | Transparent | Up to Level IV |
| Dyneema® Fibers | Extremely Strong | Very Light | Not Transparent | Up to Level III |
| Spider Silk | Very Strong | Very Light | Not Transparent | Up to Level III |
| Boron Carbide Ceramics | Very Strong | Lightweight | Not Transparent | Up to Level IV |
| Spectra® Fibers | Extremely Strong | Very Light | Not Transparent | Up to Level III |
| Depleted Uranium | Extremely Strong | Very Heavy | Not Transparent | Up to Level V |
| Graphene Polymer Composites | Very Strong | Lightweight | Not Transparent | Up to Level IV |
Conclusion
While bulletproof glass boasts tremendous strength and ballistic protection, researchers have developed and continue to engineer even stronger substances that exceed its capabilities. Materials like graphene, spider silk, dyneema fibers, and carbon nanotubes possess incredible lightness, hardness, damage resistance, and stopping power that current bulletproof glass cannot match. Their applications in armor, shields, and protective solutions will likely advance and expand in the future. However, exotic high-tech materials remain cost prohibitive for widespread commercial adoption in the near term compared to traditional bulletproof glass. Nevertheless, the quest for ever stronger and more impenetrable substances marches forward.