NIJ and military specifications for body armor and helmet systems are interesting in the one respect they always have in common: They test armor systems against threats that are many decades old. The .30-06 M2 AP hasn’t been in production in decades, and all of the stock that the NIJ uses for testing dates back to the 1950s. The 7.62x54Rmm B-32 API is every bit as old as that. These are still heavy-hitting rounds, but the threat spectrum is evolving, and armor must evolve with it.
Near-future threats that future armor might face include:
– Intermediate cartridges, in the 5.8 to 6.8mm diameter range, with high sectional densities and velocities over 3000 fps at muzzle.
– The proliferation of tungsten-carbide cored AP rounds, and “ball” rounds with hardened steel cores, like the M855A1 and M80A1. All projectiles are evolving to better defeat armor, and some are built specifically to penetrate hard armor plates at standoff distances of several hundred meters.
– Improvements in tungsten metallurgy, driven by the desire to replace depleted uranium with high-performance tungsten alloys in heavy munitions, may enable small-arms AP rounds with tungsten heavy alloy cores.
– Directed energy weapons, both high-power microwaves and high-energy lasers. These are already in-use as anti-drone weapons, they are getting smaller and more effective all the time, and they may well be directed against special operations forces in future conflicts.
From this small selection of trends, it is apparent that the armor of the future will need to stand up to heavier kinetic energy threats, and qualitatively different threats such as high-energy lasers.
In order to keep armor weight constant in the face of these threats, or even reduce armor weight, advances in materials and systems technologies will be necessary. These fall into three categories which we will consider in turn:
- Improved fiber materials.
- Improved hard armor materials.
- Improved composite system design strategies.
Improved fiber materials:
Ceramic-composite armor is a product of the 1960s, and it’s safe to say that just about all of the innovation since that time has been in fibers and fiber composites. The best hard armor plates of the 1960s consisted of a boron carbide strike-face over a fiberglass-epoxy backer. Today’s best plates are boron carbide over UHMWPE-polyurethane fiber composites. The ceramic component has not changed at all; the fiber component has gone through a number of successive generations — from fiberglass, to aramid, to polyethylene based composites.
This evolutionary process has by no means run its course, even in “conventional” fibers.
New aramid materials are in development at DuPont and at Russia’s Kamenskvolokno which should bring aramid to performance-to-weight parity with today’s best UHMWPE materials, and may even surpass them. (Kamenskvolokno’s best “AuTx” materials are already roughly at parity with today’s best UHMWPE composites.) Aramid also has superior chemical and thermal stability to UHMWPE, and it is typically much cheaper, so an improved grade could have wide-ranging implications for armor designers.
Not that UHMWPE is standing still. There are half a dozen firms that produce UHMWPE fibers and composites — including DSM, Honeywell, and Teijin — and new grades are introduced regularly. We can expect the regular introduction of better, lighter UHMWPE materials.
Other materials are, however, on the horizon.
Spider silk is a natural fibrous protein. Although even the strongest types of spider silk are roughly 50% weaker than aramid and UHMWPE, spider silk can be much more tough and flexible. It also exhibits better heat transfer than traditional ballistic fiber materials, and this, combined with its better flexibility, may make it more comfortable to wear — which may, in turn, enable the development of ballistic-resistant articles of clothing that look and feel like regular items of clothing. It was indeed once suggested that spider silk be investigated for use in ballistic resistant undergarments for groin protection from frag and shrapnel.
Spider silk is chemically and structurally complex, and has proven all but impossible to make in the lab. It consists largely of hard crystalline segments that are particularly rich in the amino acid alanine, which are joined by softer and more flexible amorphous segments that are rich in the amino acid glycine. The alanine-rich crystallites are very small — typically measuring under 10nm in each dimension. (Organic structures that fine are all but impossible to reproduce via top-down laboratory techniques, to say nothing of industrial techniques! Spider silk is a real, non-gimmick, nanomaterial.) Total crystallinity varies widely, but is often around 20-30%. These semi-crystalline protein chains are drawn and oriented into long fibers, and are coated in various natural, non-protein chemical lubricants and preservatives.
All of that simply to say that spider silk is a few orders of magnitude more complicated than any simple synthetic polymer like aramid or UHMWPE. Chemical factories can’t produce it. Period. But genetically-engineered organisms, perhaps, can. And although it has proven impossible to farm spiders for silk, the “instructions” for spider silk are present in any given spider’s DNA. If the right genetic sequence is isolated, it can be implanted into other organisms via CRISPR or other techniques. This was done with silkworms in 2014; a spider’s dragline silk gene was isolated and implanted into silkworms via plasmid-based gene transfer technique. The silk those modified silkworms produced, though neither as strong nor as tough as native spider silk, was much stronger than what they would otherwise have made, and the silkworms produced so much of it that the researchers were able to use that ersatz “spider silk” to produce a few prototype articles of clothing. Gene transfer technologies have improved by leaps and bounds since 2014 — indeed, they have arguably improved more than any other technology since then — so silkworm-derived “spider silk” might be viable in our very near future. And, after that, with some more genetic tinkering, it may well be possible to induce those worms to produce silk fibers that are stronger than any natural spider silk, while maintaining or even improving their other favorable properties such as high toughness, elasticity, etc. This would have tremendous implications for soft body armor.
There’s another interesting benefit to spider silk as a soft armor material: Its primary building blocks, glycine and alanine, are the same amino acids that are highly expressed in human skin and collagen. The application of spider silk to wounds and burns has been shown to substantially accelerate healing. (Spider silk is probably also edible and even nutritious, but you’d have to be in one hell of a bad spot….)
Carbon nanotubes are another material of enduring interest. In principle, extremely light, extremely strong, and extremely stiff, CNT-based materials could be called “super carbon fiber” — indeed, from a molecular structural standpoint, CNTs are to carbon fiber as graphene is to graphite — and CNT-based materials have the potential to not only outperform traditional ballistic composite materials, but may also displace carbon fiber in structural and aerospace applications.
If it sounds too good to be true… yeah, there’s a problem. That problem is that carbon nanotubes are short. The longest groups of nanotubes ever made, in recent research that was reported in November 2020, were under six inches in total length. This, in all fairness, is a tremendous technical accomplishment, but we’re very far from the production of spools of CNT yarn, and you can’t make a ballistic fabric unless you’re working with very long fibers, spun into yarn, and rolled in spools.
Still, research is proceeding apace. Just ten years ago, the longest CNTs measured less than an inch. Ultimately, we anticipate that both spider silk and CNT fibers will see use in armor by 2040. At the present time, those are the two materials on our radar with the highest potential. Honorable mention to M5 Fiber, if production on it ever resumes. M5 seems like a very promising material, though it doesn’t quite have the performance upside of engineered spider silk or fabrics derived from CNTs. In other words, spider silk and CNT fabrics would be revolutionary, whereas the introduction of M5 fiber would be a mere incremental improvement over today’s best UHMWPE and Russian aramid fabrics.
In an overall sense, spider silk is of greatest relevance towards soft body armor and anti-fragmentation garments. CNT fabrics are more interesting where rigid helmets and hard body armor backing layers are concerned; spider silk’s inherent advantages don’t translate terribly well to those particular applications.
On that note, there is one last thing that must be mentioned with respect to CNTs: There are, already, companies that claim to have “carbon nanotube armor.” If that is true, what these companies have done is disperse very short nanotubes in a polymer matrix. There is very little evidence to suggest that this is beneficial at all, and it is, emphatically, not what we are referring to when we talk about carbon nanotubes as an armor material. We are explicitly referring to long carbon nanotube fibers drawn into yarns and woven into ballistic fabrics. Nothing else.
Improved hard armor materials:
As mentioned previously, ceramic armor materials have been very slow to evolve since the 1960s. There are two primary reasons for this, and both of them have to do with boron carbide.
For although boron carbide was first developed and utilized in armor in the 1960s, it was very expensive back then. In fact, it was so expensive that, for a very long time, the Army didn’t want anything to do with it; until 1996, it preferred to field cheaper and much heavier plates made from aluminum oxide. Most of the “progress” between the late 60s and the mid 90s wasn’t about developing a better ceramic armor material, but about developing production technologies that would enable boron carbide plates to be fielded in large bulk quantities at a reasonable price. (These efforts were successful, due in large part to the development of “reaction-bonded” or siliconized ceramic parts. By 2006, over a million boron carbide SAPI and ESAPI plates had been issued to troops, at a relatively low average cost per pair.)
The second issue is that boron carbide, as an armor ceramic, is already very close to perfection. It combines an extremely low density with very high hardness, and — much unlike materials such as diamond, boron suboxide, and cubic boron nitride — boron carbide ceramic parts are not unduly difficult to produce. Besides, cubic boron nitride and boron suboxide don’t perform much better than boron carbide, if they perform better at all, and polycrystalline diamond’s performance advantage is on the order of 10%. Diamond aside, the list of known materials that might be better than boron carbide is very short — short enough that it can be counted off on one hand. Between 1960 and 1990, most of the ceramic materials on that short list were investigated, and all of them were found wanting for one reason or another. Simply put, it seemed that boron carbide, as an armor material, was as near perfection as modern ceramic engineering technologies could achieve, and that it would be impossible to significantly improve upon it.
In hindsight, that’s very close to the truth, but there is a major caveat which wasn’t identified until the early 2000s: The boron carbide amorphization problem. This is discussed at length elsewhere on the Adept database, so for now suffice it to say that boron carbide’s molecular structure begins to break down when it’s subjected to very high pressures in the 20-23 GPa range. These pressures are not typically attained when boron carbide ceramics are struck by steel-core AP rounds at regular small-arms velocities, but are sometimes attained when tungsten (WC-Co or WHA) or depleted uranium projectiles are employed, or when boron carbide is impacted by anything at an extremely high velocity, over 1500-2000 m/s. This breakdown in structure often results in sharply reduced ballistic performance.
Recent work has begun to identify the causes of this amorphization problem, and already offers clues as to how it might be mitigated. The solution seems to involve doping, or alloying, boron carbide with different elemental or ceramic materials — like adding a small amount of silicon to boron carbide, or adding aluminum and excess boron to produce the ternary boron carbide derivative AlB12C2.
This sort of work — the optimization of an already near-perfect ceramic material — is fairly far along. The boron carbide we use in Adept plates is silicon and titanium doped, and exhibits superior performance to standard grades. By 2025, the optimization of boron carbide will likely be complete.
Substantial, non-incremental advances in other hard armor materials seem relatively unlikely. There could be some improvement in the processing and production of boride ceramics, but it is unlikely that these materials will be meaningfully superior to an optimized boron carbide.
Incidentally, this means that there’s a floor for ceramic composite plate weight. For protection against 7.62mm AP rounds, it’s roughly 4.25 pounds per square foot — and that’s if and when there are substantial advances in fiber composite materials. Against emerging high-velocity intermediate threats with cores that are better-optimized for the defeat of ceramic armor, plates will necessarily need to be heavier than that. In this case — and also given meaningful advances in fiber composite materials — a minimum weight of roughly 5 psf seems reasonable.
Metals are worth mentioning in passing. Prior to 2021, titanium was never really a serious candidate as a body armor material. Now our titanium-faced plate already outperforms many alumina-based ceramic composite plates — and, at the same time, is much tougher, much more multi-hit capable. Incremental upgrades to the titanium plate are anticipated over the next several years, which should further improve its performance.
Steel alloys are also a domain with much untapped potential. (Which might seem surprising, given that steel is both the oldest and the most exhaustively studied of all armor materials.) New powder metallurgical techniques enable the production of very strong, enhanced-toughness steels on a small-batch basis, and we’ve already made prototypes that near the theoretical maximum strength of martensitic steels. Also, new hot-stamping techniques enable the stamping of very strong steels into complex shapes. In the very near future, armor steel will be 20-30% lighter than it already is, and may remain useful in helmets and form-fitting or lamellar stab vests for many years to come.
Improved composite system design strategies
Materials aside, there are other considerations. The main one being, “how can armor systems be modified to better counter emerging threats?”
The emerging threat of higher-potency projectiles has only one real solution: Armor will need to get thicker, stronger, or both.
The emerging threat of directed energy weapons has a number of more interesting solutions. First, a highly reflective layer can be placed on the outermost surface of the plate, behind its fabric enclosure. Done properly, this should be able to reflect anywhere from 40-96% of the incoming beam energy, depending on the laser type, energy, pulse duration, and wavelength. Second, plates can integrate layers of materials with high and low thermal conductivities — high conductivity and high melting-point materials nearer the surface of the plate, and low conductivity nearer the body side. This is already done, for all practical intents and purposes, as all of the ceramics used in armor are very high melting-point, high-thermal-conductivity materials, and all of the fiber composite materials used in backer plates have very low thermal conductivities. Still, there’s room for further optimization. Those concepts aside, there has been a great deal of published and classified work on how to shield missiles and drones from laser-based air defense systems, and very many of those concepts can also apply to hard armor plates and the bodies of soldiers.
What’s true for plates is also true for soft armor systems. There are a number of ballistic fabrics that have been coated with a ceramic material on one side. Ostensibly, this is for anti-stab purposes. But, also, it makes for what should be a very effective anti-laser armor material, particularly if multiple layers are employed.
In short, very credible anti-ballistic/anti-laser body armor can be fielded with current tech, and will likely begin to be built in the very near future.