Chameleon coating, also known as nano composite tribological coating, is an adaptive adhesive that uses nanotechnology to adjust to environmental fluctuations to make living conditions more suitable to the object that the coat has been applied to.

Purpose

The purpose of chameleon coating is to provide optimal performance of material in any environment. The idea is that when a sudden change in the environment occurs the particular nano coating will change its chemical properties to better suit itself in the environment in order to avoid wear due to friction and abrasion. Chameleon coating is supposed to resolve the issues with fluid hydraulics where atmospheric pressure changes under different environments. The chemical properties of fluid hydraulics alter under different atmospheric pressure because liquids and gases expand and condense under different pressures. Thus the goal of chameleon coating is to provide the same lubrication in machines from fluids such as oil but without the drawbacks of the coating or lubrication deteriorating under variable environments.

Development

The beginning of chameleon coating was not always nanoscaled until recent developments in nanoengineering. Before the use of nano films (coatings), the films used to provide the beneficiary aspects of the coating would break down easier and faster due to consistent wear and tear. The use of the nano thin films helped control dislocating formation of the film and helped reduce the shear rate (rate at which the film deteriorated) due to abrasion and wear several folds over. The term “chameleon coating” was used in analogy to the actual coating of a chameleon where the coat of a chameleon is able to adapt to its environment as a defense mechanism to avoid predators and increase its chances of survival. The use of diamond-like carbon for short is generally one of the nano films used to inhibit abrasion. A possible nano film that could be used to counteract temperature changes are the pure metals Ag (

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

) and Au (

gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...

). Silver and gold can withstand high temperatures and remain soft, which is desirable for coating properties. Using a lattice matrix (a template for the coating using the basket weave design), nano engineers are able to utilize properties of the diamond-like carbons and pure metals to make chameleon coatings more adaptable at even more varied environments.

Applications

The most common application for chameleon coating is in

aerospace Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial, and military applications. Aerospace engineering consists of aeronautics and astron ...

technology, where the environment is always changing due to changes in altitude. On the earth the air is humid, and temperature varies only slightly in comparison to other environments like space. The use of oil for reduced friction and wear, and lubrication applies to those ambient conditions only found on earth. When the frontier changes from atmosphere to orbit, temperatures can range from -150 °C to nearly 200 °C many of these lubrications break down at accelerated rates and thus become useless. Space satellites are under such conditions where liquid lubrication is useless as many liquid lubricants become prone to volatilization due to extremely low pressures - from nearly 100 kPa at launch, to 10 nPa in orbit. With the help of chameleon coating, the life expectancy of satellites range from 15 to about 30 years. Chameleon coatings are also often used on

hypersonic In aerodynamics, a hypersonic speed is one that exceeds five times the speed of sound, often stated as starting at speeds of Mach 5 and above. The precise Mach number at which a craft can be said to be flying at hypersonic speed varies, since i ...

and

reusable launch vehicle A reusable launch vehicle has parts that can be recovered and reflown, while carrying payloads from the surface to outer space. Rocket stages are the most common launch vehicle parts aimed for reuse. Smaller parts such as fairings, booster ...

s that require

lubrication Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology. Lubrication mechanisms such as fluid-lubr ...

in ambient atmosphere,

vacuum A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressur ...

(

space Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...

), and during re-entry (high temperature). A typical multilayer coating may use a molybdenum disulfide or diamond-like carbon for low friction at ambient conditions. A layer of

teflon Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, and has numerous applications because it is chemically inert. The commonly known brand name of PTFE-based composition is Teflon by Chemours, a spin-off from ...

may be used for vacuum service along with a

containing layer for high temperature lubricity.

References

{{Reflist Coatings Thin films