How  Does VCI-Multi-Protector / VCI2000 Work

VCIs generally come  as solid, for convenience in handling. Volatility is simply a means of  transport. Protective vapors disseminate within an enclosed space until equilibrium--determined by the partial vapor pressure--is reached. The  inhibiting process starts when the vapors contact the metal surface and condense to form a thin barrier of micro-crystals. In the presence of even minute traces  of moisture, the crystals dissolve and develop strong ionic activity.
The  result of such activity is adsorption of protective ions onto metal surfaces, with the concurrent formation of a molecular film that fosters breakdown of  contact between the metal and an electrolyte. The presence of an invisible monomolecular film does not alter any of the important properties of the metal,  even in precise electronic application, where properties such as conductivity, or dimensional tolerances are critical, and where even minute deviations could cause malfunction.
VCIs migrate to distant metallic surfaces. This ability  enables VCIs to protect metals without direct contact with metals. VCIs need only to be placed in the vicinity of the metals to provide protection. VCIs will migrate to metallic surfaces through the vapor phase and the inhibitor will be adsorbed on the surface. The protective vapors will distribute within the  enclosed space until equilibrium is reached. Equilibrium is set by the  compound's partial vapor pressure.
Too high a vapor pressure will cause the inhibitor to be released to such an extent that a protective concentration  cannot be maintained. On the other hand, a low-vapor-pressure inhibitor is not  used up as quickly and can thus assure more-durable protection, but more time is  needed for a protective vapor concentration. This raises the risk of corrosion during the initial period of saturation, and if the space is not sealed, a  protective concentration may never be reached.

Selection of VCI´s

Proper selection of  volatile compounds enables controlled and dependable volatilization. The higher the temperature, the stronger the tendency of the metal toward corrosion. The  volatilization rate of VCIs has a similar function dependence upon temperature,  so that more inhibitive material is evaporated at higher temperatures. VCIs can thus self-adjust to the aggressiveness of the environment, over a wide temperature range.  

Volatile corrosion inhibitor development

Volatile corrosion inhibitors were originally developed for protection of ferrous metals in tropical environments, an approach that soon proved limiting because of incompatibility with nonferrous metals. Recent developments are based on the synthesis of compounds that provide satisfactory "general" protection, i.e.,  they protect most commonly used ferrous and nonferrous metals and alloys.
Investigations of electrochemical behavior show that these compounds belong to family of mixed or "ambiodic" inhibitors capable of slowing both  cathodic and anodic corrosion processes. Active ingredients in VCIs are usually  products of reaction between a volatile amine or amine derivative and organic  acid. The product obtained as a result of this reaction, 'aminocarboxilates' are  the most commonly used VCIs. Cyclohexylamine, dicyclohexylamine, guanidine, aminoalcohols, and other primary, secondary & tertiary amine salts represent the chemical nature of VCIs. VCI compounds, although ionized in water, undergo a  substantial hydrolysis that is relatively independent of concentration. This  independence contributes to the stability of the film under a variety of conditions.

The absorbed film of the VCI on the metal surface causes a repulsion of water molecules away from the surface. This film also provides a diffusion barrier for oxygen, decreasing the  oxygen concentration, and thus reduction of the cathodic reaction. Strong  inhibition of the anodic reaction results from the inhibitor's having two acceptor-donor adsorption centers that form a chemical bond between the metal  and the inhibitor. Adsorption of these compound changes the energy state of  metallic surface, leading to rapid passivation that diminishes the tendency of  metal to ionize and dissolve. In addition to preventing general attack on  ferrous and nonferrous metals, mixed VCIs are found to be effective in  preventing galvanic corrosion of coupled metals, pitting attack and, in some cases hydrogen embrittlement

What are YOU doing to control YOUR corrosion problems? Are you using 1940's technology or 1990's technology? Or worse yet, nothing at all...? Is corrosion eating away your bottom line, as well as your products?? By  implementing a total corrosion control plan you can reduce rejects, returns and failures; while increasing productivity, customer satisfaction and profitability. VCI-Multi-Protector / VCI2000 packaging products are Nitrite free, environmentally  safe corrosion prevention products that provide multi-metal protection for  everything from steel rebar to electronic circuit assemblies. VCI's are  non-residual and can be applied during the manufacturing, packaging and/or operational stages of a product. A Brief History  of Vapor Corrosion Inhibitors in the early 1900's, it was discovered that a chemical could protect metal from corrosion by vaporizing and depositing on the metals. These chemicals were Nitrites, and  the first useful one was DICHAN (Dicyclohexylammonium Nitrite). This compound was developed by Shell after the Second World War to protect military equipment. DICHAN was adapted by some companies as a powder and as a paper coating to protect metal parts. However, there were early problems . . . Characteristics  of Nitrites Nitrites protect Iron  and Aluminum ONLY Nitrites attack Copper and Bronze Nitrites are known to cause health problems - Cancer, Respiratory, Visual The disposal of  nitrites causes Environmental problems Nitrites exhibit low vapor pressure It is difficult to calculate exact "dose" for application Nitrites can cause corrosion Today, Sodium  Nitrite is frequently used in Vapor Corrosion Inhibitor (VCI) paper coatings and the same problems exist with this compound. But Sodium Nitrite is inexpensive so a large quantity can be used in a coating without impacting cost significantly. So, nitrites continue to be sold and continue to give VCI's a bad reputation. In the 1950's  research began in earnest to overcome the problems associated with nitrite  based VCI's. The goals of researchers were to: Protect other metals - especially Copper Achieve higher vapor pressure to protect larger  areas Produce products that were safe to use with no health problems Solve  disposal problems - safe for water systems Make it easy to calculate amounts  for proper protection for items These programs were largely successful. New  and innovative methods were developed to deliver these new compounds; and  improved products are now available. However, the workplace is still lenient on rules protecting workers handling VCI products and Nitrites are still acceptable in most countries. The United States, Japan and Germany continue to produce Sodium Nitrite products. WHY? The low cost of Sodium Nitrite makes  it difficult for environmentally safe products to compete. Additionally,  Sodium Nitrite based products perform well in a number of tests (when health  and environmental factors are ignored). Companies like yours that are  health and environment conscious can make a difference, however. You can insist on VCI's that not only outperform Sodium Nitrite, but protect your company's products without compromising the environment or your employee's health!!