Sacrificial metals, like chromates, zincs, and aluminium, are commonly used to create conventional protective coatings. When you consider the large size of these inhibitors at the microscopic level, it leaves gaps that enable corrosion to get a strong grip in micro-cavities and then easily spread from there. A supplementary technology or an alternative to traditional corrosion inhibitors for various coatings are VCIs (vapour/volatile corrosion inhibitors), which generally come available in the form of amine carboxylates salts.
These corrosion inhibitors have a liking for surfaces made of metal, enabling the inhibitors to adsorb and create a protective and invisible molecular layer on the metals. This molecular barricade obstructs the electrochemical reaction of moisture and oxygen with metal. It slows down electron flow in the standard reaction (oxidation-reduction) that would cause rust to form otherwise.
Since Volatile Corrosion Inhibitors are smaller relatively and create a far more continuous protection layer to line a metal surface’s micro-cavities, they are at times referred to as “micro-corrosion inhibiting” coatings. Combined with the physical barrier and the metal inhibitor barrier of standard coatings, they provide a triple or double barrier against rust corrosion.
Read on to learn more about preventing rust with VCIs.
Volatile Corrosion Inhibitors (VCIs), at times known as Vapor Phase Inhibitors or VPIs, are a specific class or type of chemicals that manufacturers have designed to prevent rust corrosion progression metals. Unlike coatings, paints, and contact inhibitors, it is not necessary to apply Volatile Corrosion Inhibitors to each surface to do their job.
Furthermore, you do not have to remove them before putting items into use. The vapours get the ball rolling once they are present in a particular space (enclosed) and transport the corrosion inhibitor molecules to each metal surface.
Do You Need to Remove VCIs?
Volatile Corrosion Inhibitors often contain an oily liquid –this can easily be poured or drained out of the container if it is still present, and you can then save it for re-use. Any residual vapour will scatter over time, and the product on which you apply the VCI is completely miscible with the majority of the lubricants and fuels.
When a product is intended for potable water, food, or other contents that need high purity, it is recommended to use an aqueous VCI that you can rinse away with a food-grade product (specialist) or water.
What Sort of Products can You Protect from Rust by VCIs?
Courtesy to VCI protection, any space that is enclosed can benefit tremendously. It does not have to be sealed – closed or capped is adequate to prevent the complete escaping of vapours. Misted, fogged, sprayed, or flooded into gearboxes, engines, water or fuel tanks, empty pipelines, and pipes, the complete product is fully protected.
Also, Parts containers can gain advantage from Volatile Corrosion Inhibitor protection. Sealed packing cases or HDPE bags may have the VCI applied, so each surface is safeguarded without requiring a careful application. Furthermore, there is no need to wash or wipe components when they reach their destination, ready for assembling or coating.
Volatile Corrosion Inhibitor paper is soaked with a proprietary VCI, and it can be used to wrap parts of metal to safeguard them in storage or transit. Conventionally used to maintain and protect the edges of small-sized sharps such as razor blades and scalpels, you can cut it to size and lay it in HDPE bags or packing cases. When you do so, you enable the vapours to safeguard the products without the use and disposal of any VCI oil.
On the other hand, VCI bags have proven to be quite famous lately but are not effective in safeguarding products. Once the Volatile Corrosion Inhibitor is bound in plastic, it has a challenging time to return to the vapour phase.
The primary advantage of utilizing these products comes from when sealing the dry parts in plastic. Various VCI specialists recommend using plain HDPE (High-Density Polyethylene) bags, which are far more economical. Moreover, where extra prevention against corrosion is desirable, add a VCI paper piece into the bag or pour it in some VCI oil before sealing.
The Advantage of VCIs
As Vapor Corrosion Inhibitors can easily replace sacrificial metals, they have an environmental benefit. You can use them with great effectiveness to increase the water-based coatings’ corrosion-inhibiting ability.
The latter generally gain benefit from their lower volatile organic compounds concentration when stacked up against solvent-based coatings. Research suggests that VCIs tend to have a synergized result with other inhibitors.
As a case to point, when VCIs were combined with an acrylic coating (water-based) comprising a metal-complex inhibitor (non-zinc), the coating showed to have better protection in fog salt testing. The coating did not blister too much, and there was less corrosion on the surface of the metal than the coating comprising the inhibitor (metal-complex) only.
Summary of Benefits of VCI Technology to Prevent Rust
VCI rust prevention has advantages galore. As stated earlier, it generally does not need the proper removal of a greasy rust preventative or coating. The rust prevention solution decreases fees of hazardous waste disposal and reduces labour time to clean off conventional rust preventatives (petroleum-based), usually with solvent-based cleaners.
It also solves the issue of safeguarding intricate equipment internals (such as boilers, pipes, and valves). Moreover, it would be very challenging to apply a liquid rust preventative or coating.
Volatile Corrosion Inhibitor technologies safeguard multiple types of metal and work in several phases— interface, vapour, and liquid.
VCI is sometimes used together with desiccant bags for added protection from moisture. Hence, you can use them to prevent rust corrosion on metal surfaces above and below the fluid level in gas and oil applications or water treatment.