Today’s aerospace manufacturers rely increasingly upon composites for structural components. These composites increase strength while decreasing weight. While this has obvious advantages, damage to composites is often difficult to detect prior to catastrophic failure. During ground maintenance, simply dropping a wrench on a wing can cause stress fractures not visible on the surface to the eye, and these fractures can propagate under load in flight. During flight, impact from a bird strike, collision, or enemy fire will cause damage affecting flight capabilities, and detection of its location and severity can provide data to determine the permissible flight envelope. Besides impact, damage can also be thermal, stress, or strain. The need exists for both real-time in-flight, as well as routine maintenance detection of these types of damage.

Apply Quasam™ smart skins to critical components such as wing and control surfaces or load bearing spars. The smart skin detects the location, type, and severity of the damage. By measuring between sensor contacts, the location of damage can be readily isolated. The absolute precision can be tailored by adjusting the number of sensors used over an area. The type of damage is determined by comparison of the sensor signal with known parameters. As Quasam™ itself refers not to just one specific material, but rather a class of materials, the specific properties of Quasam™ can be optimized for each application.

The smart skin is a multilayer structure about 10 microns (0.0004 in) thick. Quasam™ forms several of the layers with different electrical insulating or conducting properties determined primarily by the degree of metallic doping. A base, insulating Quasam™ layer assures excellent adhesion and electrical isolation from metallic, conducting surfaces. Above that is the active sensing Quasam™ layer. To that, electrodes and their connections are patterned. Finally, a top, protective layer of Quasam™ is applied.

Quasam™ is produced by standard plasma-enhanced chemical vapor deposition (PECVD) techniques. Quasam™ exhibits high adhesion to most any substrate, and can be deposited upon metals, ceramics, composites, glasses, and plastics. Quasam™ consists of interpenetrating graphite-like and diamond-like phases are typically stabilized by alloying with silicone (Si), hydrogen (H), and oxygen (O) through the use of a high molecular weight siloxane precursor. Varying the metallic content through additional doping permits tuning specific properties, such the electrical conductivity. The coatings can be used for simpler applications, such as for dielectrics, charge dissipation, or field emitters. The smart skin application makes use of up to three formulations of Quasam™ in order to create the total structure: the base, adhesion and insulating layer, the active sensing layer, and the final, protective top layer. Each layer can be formed from one to several microns thick, such that the total thickness will only be about 10 microns. The typical density of Quasam™ is less than 2 g/cc, so one square meter can be covered for less than 20 g.

Because Quasam™ incorporates both diamond-like and graphite-like carbon in its structure, it also benefits by diamond’s hardness and inertness, and graphite’s smoothness. The coatings make for excellent wear and corrosion resistance, and are tribologically smooth.

The ability to identify and locate impact, thermal, stress, and strain damage, combined with light weight and protective properties, makes Quasam™ smart skin an excellent choice for aerospace damage sensors.

This portfolio includes theoretical technology that is patent protected. Related Quasam™ materials and other technology applications are in theoretical levels of development.