How do VCI Products Prevent Corrosion?
VCI products prevent corrosion in several ways. 1) By acting as a protective barrier from external dirt and abrasion, and also as a barrier to help block the diffusion of corrosive acid gas pollutants from outside the VCI Protective packaging material (such as sulfur dioxide or hydrogen sulfide) – thereby preventing contact of these corrosive gases with enclosed metal surfaces. 2) By vapor corrosion inhibitors that passivate the electron flow between the anodic and cathodic areas on metal surfaces and interrupt the electro-chemical corrosion process. 3) By adding water repulsion properties to the metal surface, which inhibit water from permeating the metal surface and providing the electrolyte for corrosion reactions. The vapor corrosion inhibitor portion of VCI products is made of proprietary chemical formulations that are invisible, odorless, non-toxic, non-reactive, non-flammable and non-allergenic. These chemical formulations release a corrosion-inhibiting vapor that diffuses throughout an enclosure that either contains VCI Protective Packaging formulations or is made from VCI Protective Packaging materials, and settles on exposed metal surfaces to form a microscopic corrosion-inhibiting layer. This protective layer will remain on the surface of the metal as long as there is no significant, continuous exchange of air & moisture within the enclosure. Ideally, there should be less than one air exchange per day (for example, when an electrical cabinet or package is opened briefly and occasionally). Once the metal part is removed from the enclosure, the corrosion-inhibiting layer is no longer kept in place by equilibrium with the VCI Protective Packaging source, and it dissipates from metal surfaces (typically within about an hour) leaving the metal part clean, dry and corrosion-free. The vapor diffusing properties of our corrosion inhibiting formulations offer an important advantage over conventional inhibitor coatings since the traces of these gas molecules penetrate into inaccessible crevices, gaps, and slots, reaching the surfaces of complex-shaped articles that are difficult to coat. They are adsorbed onto the surface of the metal to form a corrosion inhibiting protective layer that is just a few molecules thick. VCI products may also include acid gas absorbing chemicals in the packaging material to act as a barrier and add another dimension to the protection of the metal content. These “scavenging” chemicals react and neutralize the polluted air that may diffuse through the VCI material. Also used are various combinations of physical barrier properties that optimize the corrosion prevention and physical protection needs of our customers. These may range from plain low density polyethylene (LDPE) material to combinations of higher strength, higher tear resistance, higher resistance to sunlight or UV, static charge dissipation, and lower diffusion for moisture or acid gas molecules. VCI products offer corrosion protection without having to be in direct contact with or coated onto the parts that are being protected. Metal parts merely need to be enclosed in or with a VCI product (where airflow is minimized) for protection to occur. With VCI, it is no longer necessary to apply messy oils, greases and other corrosion protection compounds and incur the cost of their removal.