Definition - What does Metal Dusting mean?
Metal dusting is an extremely destructive type of corrosion which takes place when materials at risk are exposed to high-carbon atmospheres. The corrosion is evident as the breakdown of bulk metals into metal powder.
The primary probable mechanism is graphite deposition on the metal surface that typically forms CO or carbon monoxide in its vapor state. The layers of graphite are transformed into a metastable form that travels away from the surface of the metal. In other cases, it can be described as the metal atoms directly transforming to graphite layers.
Corrosionpedia explains Metal Dusting
Metal dusting involves factors such as:
- Temperature: Typically 450-800°C (840-1470°F)
- Environment: In the gaseous state, potentially reducing and carburizing with or in the absence of oxygen
- Product: Powder or dust composed of metal oxides, metal carbides as well as a mixture of graphite and metal
- Form: General pitting, localized or total surface damage or carburization
This form of high-temperature deterioration can be very dangerous since the growth rate of metal dusting pits may run at one mm a month on materials like stainless steel. The magnitude tends to be higher in cases of low alloys.
Metal dusting is a prevalent issue in the industry of petrochemicals, specifically in reforming units and cracker furnaces. In such, gas that is capable of synthesizing water vapor contains H2 and CO as well as water vapor. Thus, all monomer that is a main material in polymer production may undergo metal dusting. Other examples of industries that can be affected by this corrosion type are those involved in energy production, ammonia plants and heat-treating facilities.
The solution for these issues relies on developing new technologies where only the hydrogen components of fossil fuels are utilized for the production of energy. Along with this, more efficient techniques for conversion that permit the production of natural as an alternative to oil or gas would help in the prevention of metal dusting.