During storage and transport
temporary corrosion protection
Temporary corrosion protection describes measures taken to protect metal surfaces from corrosion during transport, storage, and processing, as well as during machine downtimes. Easily removable substances and methods are used for this purpose.
These temporary protection methods can take various forms, such as:
- Applying corrosion inhibitors: Applying liquid or highly viscous oils, greases, or waxes to the metal surface keeps moisture away. The inhibitors in the corrosion inhibitors also inhibit the corrosion reactions on the metal and protect against corrosion.
- Use of VCI protective films: VCI films protect metallic packages from external influences. Furthermore, the inhibitors are able to escape from the VCI film and saturate the sealed-off atmosphere, coating the metal surface and preventing or slowing down corrosion processes.
- Desiccant method: Storing metal parts in dry environments can also provide temporary corrosion protection. In packaging technology, barrier films in combination with desiccants are used for this purpose. This method is specified according to DIN 55473.
- Use of corrosion inhibitors: Chemical additives are used, for example, in cleaning agents or cooling lubricants (CML) to prevent adverse corrosion reactions on the metal surface during or after machining. The duration of protection is usually limited to days or a few weeks. They are only suitable for corrosion protection during transport in conjunction with oils or waxes.
The safest method
VCI corrosion protection
In the field of corrosion protection, VCI stands for "Volatile Corrosion Inhibitor." These substances are designed to generate the corrosion protection process via the vapor phase. This process can be described in several steps:
- Evaporation: VCI substances are embedded in carrier materials such as paper, foil, or foam. These substances evaporate slowly and continuously when exposed to air.
- Diffusion: the vaporized VCI molecules disperse into the air and spread into the surrounding environment. They fill the enclosed space in which the metal is stored and create a protective atmosphere.
- Adsorption: the VCI molecules settle on the metal surfaces and form a microscopically thin protective layer. This layer is usually invisible, just a few atomic layers thick, and has no adverse effects on the metal or its properties.
- Corrosion protection: the VCI layer actively influences the corrosion reactions and protects the metal surface from corrosion by water and oxygen.
- Reversible effect: once the VCI-protected materials are unpacked, the protective molecules evaporate from the surface and the layer disappears. The metal is then immediately ready for use and requires no cleaning or special treatment.
