Vapour phase corrosion inhibition is a science that employs vapor phase corrosion inhibitor technology for corrosion protection. The VCI inhibitors can continuously and slowly vaporize at room temperature, with the corrosion-inhibiting gases volatilizing and adsorbing onto the exposed metal surface to form a stable protective film that is one to two molecules thick. This protective film effectively prevents corrosion of the metal by environmental factors such as oxygen and moisture. Due to the continuous volatilization of the vapor phase corrosion inhibitors, they maintain a "saturated" state in enclosed spaces, thereby achieving long-term, stable, and excellent rust prevention effects.

Firstly, this protection is all-penetrating. Some workpieces have slender, curved holes or narrow blind holes that are often difficult to prevent rust, even with oiling. However, using atmospheric rust prevention agents can easily accomplish the anti-rust measures. In fact, atmospheric rust prevention agents are an active anti-rust material; as long as the sealed environment is permitted and the anti-rust agent remains, it can continue the anti-rust state. Unlike rust prevention oils and coatings, which lose their anti-rust function once the coating is damaged, its anti-rust protection period is very long. It is commonly used in the military for weapon anti-rust, with a long-lasting anti-rust period of up to 12-20 years. Its use, protection, and removal are very convenient; simply place the workpiece with it and use a sealed bag like Nantong Yongyu anti-rust plastic bag to complete the anti-rust protection. To remove, just open the sealed bag, take it out, and it's ready to use. Moreover, in recent years, as European exports of electromechanical products often require oil-free anti-rust, as rust prevention oils can turn into wastewater, causing pollution in importing countries. Therefore, the application and usage of atmospheric rust prevention agents will continue to grow, and it is predictable that in the near future, they will become one of the main anti-rust materials for steel.

Vapor phase corrosion inhibition is a new type of corrosion prevention material. To make the most of it, one must understand its essence. Only by mastering its usage characteristics can it perform exceptionally well in corrosion prevention. Here is a brief introduction to its features:

Sealability:

Vapor-phase corrosion inhibitors rely on the accumulation of nearly saturated corrosion inhibitor concentrations on the workpiece surface, requiring a sealed, non-ventilated micro-environment. This necessitates packaging with good sealability; otherwise, escaping gases can cause the corrosion inhibitor in the micro-environment to deviate from saturation, resulting in failed corrosion protection. On the other hand, poor sealing allows the vapor-phase corrosion inhibitor gas to decompose continuously before reaching saturation, leading to abnormal consumption and缩短 the protection period.

Temperature Impact:

When temperatures exceed 60°C, most vapor phase corrosion inhibitors break down rapidly. Hence, hot workpieces can excessively consume vapor phase corrosion inhibitors; it's advisable to use the material for packaging after the workpieces have cooled completely.

Humidity Impact:

Moisture has a significant impact on metal corrosion, so efforts should be made to minimize its effects during use. Generally, vapor-phase corrosion inhibitors with a longer induction period are suitable for environments with relative humidity below 45%, while those with a shorter induction period are required when the relative humidity exceeds 80%.

Types of Vapor Corrosion Inhibitors:

Vapor-phase corrosion inhibitors can be mainly categorized into three aspects: induction period, type of protected metal, and product form. The induction period, which can be long or short, corresponds to a vapor pressure of one ten-thousandth of atmospheric pressure. This induction period typically requires about 20 hours, which is a drawback. However, the low vapor pressure and slow evaporation allow it to continuously work over an extended period, ranging from 10 to even 20 years. The type of metal protection is another way to differentiate vapor-phase corrosion inhibitors. A single inhibitor often cannot protect multiple metals, so it's essential to select the appropriate agent based on the target metal. In some cases, a vapor-phase corrosion inhibitor may even accelerate corrosion of a specific metal, such as cadmium, magnesium, and others, to varying degrees. This highlights the importance of choosing the right agent.

Common vapor corrosion inhibitors include powders (including tablet powders), solutions, solvents, corrosion-preventive papers, and oils. Solutions, corrosion-preventive papers, and oils are all composed of basic powder materials and other components. Powders are commonly used in complex cavities such as boilers, heat exchangers, and gearboxes, as well as for loose workpieces, requiring only 34g per cubic meter of space. For example, Nantong Yongyu Antirust Material Co., Ltd. produces antirust powder, which can be blown into place using compressed air. If the powder is dissolved in water, it becomes a solution, often used in hydrostatic testing and full water storage, with a usage rate of 0.02%-0.1%. After the workpiece is immersed in the liquid, the surface immediately comes into contact with the agent, without any induction period, and since the agent is close to the workpiece and evenly distributed, the effect is better, although the application process is麻烦.

Vapor Corrosion Inhibitor Paper is a development from the powder form, which involves dissolving the powder in a solvent and then absorbing it onto a paper with good strength. Compared to the powder, its effective surface area increases by dozens of times, and the linear distance to the workpiece is shortened, resulting in better performance and wide application. Vapor corrosion inhibitors can also be dissolved in lubricating oil to create vapor corrosion inhibitor oil. It is commonly used during machine tool and mechanical trial runs, where the oil can prevent rust in the internal cavities. After the trial run, the cavities can be sealed, and upon unsealing, cleaning does not need to be overly strict; a small amount of residue will not affect normal operation. Vapor corrosion inhibitor oil is also frequently used for rust prevention coating on the edges of rolled steel and copper strips, with excellent results.