Volatile Corrosion Inhibitors Research Articles

Use of dicyclohexylamine nitrite in inhibition of coupled zinc and steel

The effect of dicyclohexylamine nitrite (DCHN), a volatile corrosion inhibitor, on the corrosion behaviour of steel, zinc, and coupled steel and zinc was studied. Corrosion rates were determined using mass loss methods as well as potentiodynamic polarisation and ac impedance measurements. Potentiodynamic polarisation studies show that DCHN acts as an anodic inhibitor in the corrosion of mild steel. However, for zinc, DCHN acts to accelerate corrosion. This is attributed to surface chelation between DCHN and zinc, resulting in the formation of a soluble complex. Zero resistance ammetry was used to investigate the dissolution behaviour of a galvanic couple between steel and zinc in the presence of DCHN; in such as situation, the inhibitor effectiveness depends mainly on its concentration.

Use of dicyclohexylamine nitrite in inhibition of coupled zinc and steel

The effect of dicyclohexylamine nitrite (DCHN), a volatile corrosion inhibitor, on the corrosion behaviour of steel, zinc, and coupled steel and zinc was studied. Corrosion rates were determined using mass loss methods as well as potentiodynamic polarisation and ac impedance measurements. Potentiodynamic polarisation studies show that DCHN acts as an anodic inhibitor in the corrosion of mild steel. However, for zinc, DCHN acts to accelerate corrosion. This is attributed to surface chelation between DCHN and zinc, resulting in the formation of a soluble complex. Zero resistance ammetry was used to investigate the dissolution behaviour of a galvanic couple between steel and zinc in the presence of DCHN; in such as situation, the inhibitor effectiveness depends mainly on its concentration.

The Desorption of a Volatile Corrosion Inhibitor from Polyethylene

The kinetics of the desorption of a volatile inhibitor of atmospheric corrosion, hexamethyleneimine m-nitrobenzoate, from polyethylene film at 298–333 K was examined. The dependence of the desorption rate on concentration and the character of the inhibitor's distribution in the film was revealed. Effective diffusion coefficients of the inhibitor in polyethylene, as well as activation energy of the diffusion process, were calculated. Recommendations on the practical application of the inhibited film were offered.

On steel protection with volatile corrosion inhibitors in H2S-containing media

The corrosion behavior of aCt3-type steel in hydrogen sulfide media, including those containing CO2, is studied. The inhibition effects of a volatile, water-soluble inhibitor (IPKhAN-72) and the starting aliphatic amine for its synthesis are compared. IPKhAN-72 is found to be more effective, especially in the presence of CO2. In CO2-free hydrogen sulfide media, IPKhAN-72 functions as an anodic inhibitor. In the presence of CO2, it also decelerates the cathodic process.

Corrosion behaviour of metals in SO2 environment and its prevention by some volatile corrosion inhibitors

Atmospheric corrosion of mild steel, copper and zinc was studied in SO2 environment under dynamic flow conditions by weight loss measurements, and their corrosion prevention by the use of volatile corrosion inhibitors such as cyclohexylamine (CHA) and dicyclohexylamine (DCHA) is discussed. These studies assume importance as SO2 is one of the dominant pollutants in the atmosphere and more so in industrial belts affecting the stability of metal articles to a greater extent.

Host-Guest Systems in the Development of Anticorrosive Polymeric Films

ABSTRACTInteractive dispersion-type LDPE/EVA films with anticorrosive properties were produced using host-guest systems of thermally stable volatile corrosion inhibitors (VCI) dicyclohexylammonium p-nitrobenzoate and phosphate, adsorbed on NaY zeolites and diatomaceous earths. Carbon steel specimens were either directly exposed to the inhibiting systems studied or wrapped with the additivated films. Accelerated corrosion tests were carried out where the inhibitive properties of the systems being studied were determined by mass loss of the test coupons. The influence of the mineral support on the volatility of the corrosion inhibitors was evaluated by TG/DTG techniques. The obtained results may be regarded as a confirmation of the hypothesis that VCI volatility may be controlled by their deposition on determined supports. Also, both VCIs had their efficiency enhanced by zeolites, and the phosphate greatly benefited from the use of diatomaceous earth.

A new method for quantitative evaluation of volatile corrosion inhibitors

A new method to evaluate volatile corrosion inhibitors was developed. The assembly enables a fairly accurate simulation of operational conditions. Problems associated with contamination of equipment are eliminated and reliable quantitative results are obtained.

The role of volatile corrosion inhibitor oil

In the continuing struggle against corrosion one of the most difficult problems to contend with is that of internal corrosion in inaccessible areas. Surfaces which cannot conveniently be coated with paints, lacquers or protective oils, and yet which are subject to corrosion arising from the condensation of moisture, can be extremely difficult to preserve.

Investigation of the adsorption and determination of the heats of sublimation of volatile corrosion inhibitors

1. A gas-adsorption method was used to determine the latent heat of sublimation of hexamethyleneimine benzoate (∼27 kcal/mole) and the number of hexamethyleneimine m-nitrobenzoate molecules adsorbed per square centimeter of iron and nickel powders (2·1011 and 6·1011, respectively). 2. The method makes it possible to study the adsorption of inhibitors at extremely low degrees of surface coverage and also to determine the vapor pressures and heats of sublimation of volatile corrosion inhibitors.

The distribution of a volatile corrosion inhibitor (CHC) on corroded Fe

An investigation has been made to determine the distribution of the volatile corrosioninhibitor CHC on Fe and to identify the inhibitive groups of the inhibitor. Autoradiographically it has been shown that CHC acts both as an anodic and a cathodic inhibitor with CO 2 as the cathodic cyclohexylamine as the anodic part.

Vapor Pressures of Volatile Corrosion Inhibitors by the Torsion-Effusion Method.

V O L A T I L E corrosion inhibitor is the name applied to compounds which have the ability to vaporize and condense on a metal surface making it less susceptible to corrosion. One of the most important properties of these compounds is vapor pressure. Cyclohexylammonium carbonate, for example, has a high vapor pressure of 0.4 mm. of mercury a t 25 C. and is a very effective corrosion inhibitor. The protective time is very short because of rapid depletion of the inhibitor. There are also inhibitors with low vapor pressures on the order of lo-' mm. of mercury. These compounds, however, cannot vaporize quickly enough before corrosion occurs. Therefore, vapor pressure is important, since it determines the usefulness of the compounds. To utilize volatile corrosion inhibitors it is also important to know the rate of vaporization or the vapor pressure change with temperature. A vapor pressure-temperature curve with 1 / T us. the -log P(mm. of Hg) will ,provide information which can later be related to the effectiveness of the various volatile inhibitors. Most of the information on volatile corrosion inhibitors in the literature does not pertain to their physico-chemical properties, and some of the data are conflicting. For example, the value for the vapor pressure of dicyclohexylammonium nitrite a t 21°C. determined by Rozenfeld ( 4 ) and by Wachter (7) is different by a factor of 10. Therefore, it seemed necessary to find a method which would accurately determine the vapor pressures of these compounds and the@ rates of change with temperature.

銅用気相腐食抑制紙の試験法

銅用気相腐食抑制紙の試験法

GASEOUS SYSTEM OF CORROSION CONTROL:Turbo‐Jets Protected by VPI

The protection of metal parts with volatile corrosion inhibitor (VCI) or vapour‐phase inhibitor (VPI) materials has been receiving increasing acceptance in the packaging field because of the simplicity of the wrapping and depreservation procedures. Unlike the preservative oils which function by excluding moisture, these compounds function in the presence of moisture and oxygen on ferrous metal surfaces. The action is somewhat similar to that of a rust inhibitor in an automobile radiator. However, instead of distributing the inhibitor as a liquid, volatile inhibitors depend upon gaseous diffusion of vapours and require smaller quantities of inhibitor than the preservative oil procedure. There is the added advantage that the equipment can be stored in an operable, yet protected, condition.

Dicyclohexylammonium Nitrite, A Volatile Inhibitor for Corrosion Preventive Packaging

Dicyclohexylammonium nitrite is a powerful inhibitor for corrosion of steel by fresh water. Since this nitrite salt is slightly volatile, it has commercial application in a new method for preventing corrosion of packaged steel articles by the moisture that enters or is present within a package. It functions by vaporization and transport of its vapor to the metal surface where it condenses or dissolves in condensing moisture. The duration of protection is dependent upon the quantity of inhibitor present and the rate of loss as vapor and by decomposition. The compound has properties of chemical stability, compatibility, volatility, vapor transport, diffusion, solubility, and corrosion inhibition, that are important to its functions as an inhibitor in packages. The absence of undesirable effects with nonmetallic materials, nonferrous metals, bi-metallic couples and in handling by people are also of practical importance.A large number and variety of tests in the laboratory and in outdoor exposure racks have given information on the performance of the inhibitor under many different conditions. A dynamic corrosion test has been developed that is useful for rapid evaluation of volatile corrosion inhibitors for packaging applications.The inhibitor is most conveniently and effectively employed in the form of a coating on wrapping papers or on paperboard containers. In order to obtain good results it must be used properly. It is not a panacea.