Electrochemical Investigations on Weapon Oils

Electrochemical Investigations on Weapon Oils

Based on the different military operation areas weapons are exposed to various climate zones and therefore to atmospheric corrosion. Splash water or sea water aerosols have also to be considered.

For corrosion protection and lubrication of mechanical components on fire arms made of high strength carbon steels weapon oils are doped with specific surface active additives. Due to mechanical and tribological restrictions, organic coatings or metallic layers often cannot be used. It is also not possible to use corrosion-resistant steels as an alternative because those do not have the mechanic properties required. 

In military and civil standards the corrosion protection efficiency of weapon oils mostly is tested in climate chambers, e.g. ASTM B 117. In the German Army the qualification requirement for weapon oils is the protection of panels of carbon steel in the salt spray cabinet for at least 72 hours.

Due to the test procedure the viscosity, thickness and uniformity of the oil film applied are of great importance. The results of the test are often not reproducible or the scatter in experimental data is great.  

By the use of electrochemical test methods e.g. Electrochemical Impedance Spectroscopy (EIS) or polarization measurements, a discrimination between good and bad oils as well as a good ranking within these groups was possible. Advantages of the electrochemical tests are low costs compared to environmental simulation and low sensitivity against uncontrolled experimental parameters.

In the next steps the criteria for qualification requirements have to be defined and after that new test methods have to be implemented into the technical specifications.