VT: Self-Healing Materials and Related Technology

Presiding Author: DROA-499

It is hard to overstate the relevance of current Self-Healing technologies. They've managed to work their way into nearly every application imaginable- while not entirely ubiquitous, these offer massive advantages to the low-density, long-endurance state of the current strategic and tactical environment, to say nothing of general applications in more passive roles.

History

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Say it with me class: we use these words a bit differently than we used to. Old self-healing technology was... Not, in a lot of ways. Rubber that would elastically close a hole poked in it up, foam coats that would saturate and expand when wetted with fuel to seal back up, so on and so forth.

The field of material memory became relevant here- materials that could change back and forth between arrangements. A spring that, when straightened, coils itself back up under heat, and forging processes that leveraged tendencies for materials to warp and rearrange themselves when given energy.

Then came the real advances. Materials science marches on and all. Several approaches exist, to varying degrees of effectiveness.

The "True" self-healing materials were arguably first, and were offshoots of technology that led to practical legged vehicles and Autosprings. Ironically, it was only after this that the simpler coagulant methods would be advanced to their current states, forming a complement to them.

True Self-Healing Materials (EARC/M)

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Entropy/Electrically-Activated ReCrystallization/Moulding is the more technical name of the "True" self-healing material class. A variety of materials exist that benefit from this effect, including both amorphous (Moulding) and crystalline (Crystallization) solids.

The principle behind these material systems is to force a material to reshape itself when exposed to high amounts of heat or current. The material bears self-arranging tendencies, and heating causes its crystal units to reshape according to a "memory" impressed into it during forging via gradients in its composition.

At first, this was extremely subtle, and only applicable to relatively thin, flexible structures. This, simply put, changed. A lot.

EARC/M possesses a potential downside of deforming, and putting strain on surrounding parts- including the risk of this being used as an attack via electrical or thermal weapons. However, it's proven useful even in tight-tolerance conditions, able to even bring engines that have been perforated back online. Most of the time it just fights material fatigue, but the ability of certain engines to leverage their own thermal waste to grant the capacity to restart themselves after minutes of being out of operation is frankly shocking. Structure and armor heal, and even holes will re-knit into shallow dents- the only loss is material jettisoned from the system, and the occasional risk of something getting jammed up.

That being said, there's still limits. It takes a lot of energy- heat is readily available in small amounts, but providing an electrical current can speed things up greatly, which can make it reliant on the platform's (or an assisting platform's) power generation. Meanwhile, it can't just generate mass, so anything just lost is gone, and there's always the fact that enough damage will "scramble" the differentials of material that enable reshaping, overwhelming it and rendering it unable to return to its original geometry. The most significant downside is that these tend to be made of materials with less favorable sheer strength/weight ratios, which limits material choices if you aim to use this technology.

Coagulants

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Coagulants are a subset of self-healing technology that requires more internal space and can still be depleted, but offers a bit more flexibility of use. The material hardens in some way or another upon impact, filling in damaged places with itself.

The end result of a coagulant is often a hard, low-density substance, such as a metal foam or aerogel. The reaction is quick and violent, and can potentially backfire in situations of extreme damage by impinging upon other systems or warping structures- but that's fairly easy to dismiss given what that'd take. Coagulants often do not preserve external geometry, and tend to restore the material as weaker than it was due to material inconsistencies. The supply may also deplete more quickly after a few big hits.

Coagulants, of course, synergize well with self-healing material. There has been limited success with using coagulants in conjunction with true self-healing materials in a much more extensive way, however. Currently in LRIP, these simply have the coagulant produce an EARC/M (more commonly EARM, using polymers as a base). This covers the weakness of true self-healing being generally unable to replenish the material it works on, and the weakness of coagulants not producing coherent structures. The drawback is that these tend to be fairly weak, even moreso than the limited characteristics of EARC/M, mostly high-density polymers with a few metal inclusions.

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