Corrosion Protection For Steel

Steel is a durable and cost-effective metal. But when exposed to the atmosphere, it starts corroding. A considerable amount of resources are wasted annually in metal industries due to metal corrosion. The phenomenon of corrosion adversely affects and causes deterioration in metals through oxidization. Steel corrosion is an electrochemical process, and the coinciding existence of moisture and oxygen in the atmosphere leads to corrosion. The reaction starts when the oxygen in the atmosphere oxidizes iron in the presence of water.

Also, the emissions of gases in the atmosphere like carbon dioxide (CO2), carbon monoxide (CO), sulphur dioxide (SO2), nitrous oxide (NO2), and many other chemicals can accelerate the corrosion process. Additionally, if any two metals with different potentials come in contact with each other, current will flow, and the more reactive metal will corrode in comparison to the less reactive metal; this is called bimetallic or galvanic corrosion.

The rate at which the corrosion will progress depends upon the climatic condition around the steel. The high level of moisture/wetness and pollution in the atmosphere would cause corrosion at a much faster rate and vice versa. Therefore, the rate of corrosion is different in different places due to variations in atmospheric conditions. And, hence it is essential to do Corrosion Protection for Steel.

Below are some protection methods which can stop or slow the corrosion process.

Protective Coating for Steel Rust Protection

Here the steel is coated with a protective layer which works as a barrier between the metal and oxygen, water, or ions from the atmosphere. Lower permeability of water by the coating will ensure better protection. The coating can be Paint coating which gives improved durability to steel, or it can be Metallic coating. The four commonly used methods of applying a metal coating to steel are hot-dip galvanizing, thermal spraying, electroplating, and sherardizing.

Moreover, Zinc has high corrosion-resistant properties and is used as a protective coating on many products and under many conditions. The quality of the coating, its selection, its application, and handling are all important factors in deciding the kind of protection offered. If maintenance acts are not carried out regularly, the protective coating can become ineffective. This happens when corrosion takes shape beneath the film of the coating. It is very important that protective coatings are to be carefully handled while setting up so that they last long as considered.

Hot-Dip Galvanizing

In this process, fabricated steel or iron is immersed in a kettle of molten zinc. The steel reacts with the zinc to form an alloy coating. The process provides a barrier and cathodic protection resulting in Corrosion Protection for Steel lasting decades. This method resists corrosion through the buildup of zinc plating and provides protection to galvanized steel and issueless longevity.

This is an ancient method that originated more than 250 years ago. But, the latest technology and innovative chemistry have led to the unrelenting advancement of this established method.

Duplex System

This system consists of providing paint or powder coating over hot-dip galvanized steel. This provides enhanced corrosion protection than either of the individual methods. Many people are aware of one or the other method of corrosion protection. Whereas, there are some people who know the fundamental value of applying two methods together. It is what is described as the duplex system. This distinguished manner of protection against corrosion is a synergistic effect. An additional obstruction is created with the outer layer of coating, which significantly lengthen the existence of galvanized steel.

Special Steels

Different steels like stainless and weathering have special chemistry and elements. They provide corrosion resistance by taking advantage of these unique properties.

Stainless steel contains iron and chromium, and the presence of chromium ensures excellent stain and rust protection. Stainless steel has an exceptional defense against rust and stain as it contains a considerable percentage (12-20) of chromium. Steels with austenite and nickel also provide improved ductility and superior resistance to corrosion. This steel is named austenitic stainless steel. Another kind of stainless steel is Ferritic stainless steel which has greater resistance to stress corrosion.

Weathering steel contains copper and develops a natural iron oxide patina that, once formed, is stable. The steel is allowed to rust, after which it creates a protective layer or patina. A layer protecting the surface is developed. Compared to carbon steel, weathering steel offers increased corrosion protection.

Sacrificial Protection (Cathodic Protection)

The reaction between two dissimilar metals can be used to protect against corrosion. Zinc is a widely used metal for steel rust protection. Protection is offered through preferential oxidation by placing zinc in direct contact with the steel. Zinc corrodes against steel and effectively stops the oxidation reactions on the steel. Also, zinc normally corrodes at a slower rate. Three metals that are mostly used in this method are aluminum, magnesium, and zinc. Aluminum and zinc are used mostly in saltwater.

Read Also: Corrosion Resistance with Rust Prevention Oils

Temporary Barrier for Steel Rust Protection:

Rust Preventive Oil, VCI or Volatile Corrosion Inhibitor, etc. Temporary Barrier Protection is the conventional rust protection method and is found to be one of the appropriate methods to protect the parts from rust for a short period of time in the steel industry, as it allows for flexibility in application, excellent confluence with upstream and downstream requirements & is considered very economical.

NOX-RUST Rust Preventive Oils are based on CCI or Contact Corrosion Inhibition Technology and have been found extensively useful in the protection of temporary protection of steel in challenging climates and conditions. Based on the concept of polarity & thin Film Technology, Daubert proprietary polar molecules do not allow any oxidizing elements to permeate even under condensing climates faced during the height of the rainy seasons and are able to survive thermic stresses beyond most other rust preventives in similar categories.

The exceptional ability of NOX-RUST to remove pre-existing moisture and light alkaline from the metal surface further augments its performance under moist application and storage conditions. NOX-RUST offers a broad range of rust preventives which, besides corrosion protection, can be selected on the basis of needs such as water displacement properties, film thickness, upstream and downstream compatibility requirements, and many more.

Similarly, Daubert’s VCI Technology is based on the concept of Volatility & Polarity and performs favorably even in the presence of moisture. Daubert unique VCI technology enables it to complex with the moisture present in the air therefore retarding or often neutralizing its corrosive effects. Daubert VCI technology-based products are made available in various forms such as oils, packaging papers, and films, emitters, powders which allow their use in multifarious applications across a broad spectrum of industries and at different stages of the product life cycle.

An optimized and effective Corrosion Protection Method can be developed by Daubert Solution Engineering Team, which can be validated by various accelerated corrosion tests and field trials.