Corrosion Inhibitors for Military Applications
A corrosion inhibitor is essentially a chemical compound that has the ability to decrease the corrosion rate of many different types of material like alloys and metals. It is usually used by first adding it to liquid or gas. The better the fluid composition, flow regime and quantity of water the more effective the corrosion inhibitor will be. It works by preventing the corrosive substances from accessing the metal.
Hence it necessary to ensure the corrosion inhibitor is first applied to the metal so that it can form a protective coating and prevent corrosion. Such corrosion inhibitions can be in the form of a spray (usually in a combination of lubricant & penetrating oil) and are often available over the counter.
This article goes on to describe the types of corrosion inhibitors and why it is invaluable to the military.
Types of corrosion inhibitors
A corrosion inhibitor has the ability to decrease the corrosion rate when the metal is exposed to environmental elements like air and water. It is essentially a chemical solvent. There are several types of corrosion inhibitors:
- Anodic inhibitor: This type of inhibitor creates a preventive oxide film over the exterior of the metal it is applied on. This helps reduce the effects of corrosive substances by creating a chemical reaction and causing a large anodic shift to protect the metallic surface. Some examples of anodic inhibitors include chromate, nitrite, molybdate, and orthophosphate.
- Cathodic inhibitor: The cathodic inhibitor can either slow down the cathodic reaction or restrict the diffusion of eroding elements onto the metal surface. Although this is successful at reducing the corrosion rate, it results in increasing the sensitivity of the metal to hydrogen-induced cracking. This is because during the process hydrogen is often absorbed by the metal. This includes material like sulphite, bi-sulphite, etc.
- Mixed inhibitors: As the name suggests this is a mixed inhibitor that reduces the effect of the cathodic and anodic reactions. It is a film-forming compound and includes compounds like silicated and phosphates that are often used with domestic water softeners.
- Volatile Corrosion Inhibitors (VCI): This is also called Vapor Phase Inhibitors (VPI). It prevents corrosion by volatilization from several sources. For example, a boiler includes volatile basic compounds that are carried with vapour to prevent corrosion in the condenser tubes.
Military Applications:
There are many applications for the military as explained here:
- Protects hard to reach places and profiled metal surfaces.
- It does not require any special preparation.
- It is very easy to implement since there are many methods of doing so.
- They are usually not harmful to humans; besides which they are also environmentally friendly.
- It is more economical to implement and also ensures all the military equipment is ready for combat.
- The application of a corrosion inhibitor prevents the rusting at the same time does not affect the normal functioning of the equipment.
- It protects many different types of metal and the application process is not time-consuming, hence it is also not a labour-intensive process.
The corrosion inhibitors are also invaluable to military aircraft manufacturers. It is useful for electrical and close mechanical applications. Military aircraft have several common issues like salt fog during their flights over mountainous regions. Special inhibitors are used by the military in such case to prevent corrosive damage. It has the ability to protect the electronics of the plane and even other surfaces that are exposed to several dangerous chemicals. The dangerous chemicals can be Sulfur Dioxide (SO2), nitrogen dioxide (NO2), Hydrogen Sulfide (H2S), Chlorine based gases (CL12), Ammonia (NH3), etc.
For example, it is used in the F16 aircraft to ensure the avionics and electronics systems function fine. It is useful in preventing corrosion on several components of the F16 warcraft and several other warcrafts; it includes components like switches, connectors, electronics, electrical systems, avionics. It has similar applications on the aircraft P 3 Orion which is an electronic surveillance aircraft used by the Navy.
