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Metal Dusting Carburisation And Nitridation: Unraveling the Intricacies for Engineers and Researchers

Marc Foster

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Published in Corrosion By Carbon And Nitrogen: Metal Dusting Carburisation And Nitridation (European Federation Of Corrosion (EFC) 41)

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In the realm of materials science and engineering, the phenomena of metal dusting carburisation and nitridation have garnered significant attention due to their profound implications for industrial processes and equipment performance. These complex reactions involve the degradation of metallic components in environments containing carbon and nitrogen, leading to the formation of brittle carbides and nitrides that severely compromise material integrity.

This comprehensive article delves into the intricacies of metal dusting carburisation and nitridation, providing a thorough understanding of their mechanisms, consequences, and mitigation strategies. By exploring the latest research findings and industry best practices, we aim to empower engineers and researchers with the knowledge necessary to address these challenges and safeguard the longevity of their applications.

Corrosion by Carbon and Nitrogen: Metal Dusting Carburisation and Nitridation (European Federation of Corrosion (EFC) 41)

Corrosion by Carbon and Nitrogen: Metal Dusting, Carburisation and Nitridation (European Federation of Corrosion (EFC) Series Book 41)

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Language	:	English
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Understanding Metal Dusting Carburisation and Nitridation

Mechanism of Reactions

Metal dusting carburisation and nitridation are distinct yet related processes that occur when metallic surfaces are exposed to atmospheres containing high levels of carbon and nitrogen, respectively. In both cases, the reactions involve the formation of volatile metal carbides or nitrides that sublime from the metal surface, leaving behind a porous and brittle layer.

For carburisation, the reaction proceeds as follows:

M + xCO -> MxCy + CO2

Where M represents the metal, x and y are stoichiometric coefficients, and CO and CO2 are carbon monoxide and carbon dioxide, respectively.

Similarly, for nitridation, the reaction can be expressed as:

M + xNH3 -> MxNy + H2

Where NH3 and H2 represent ammonia and hydrogen, respectively.

Consequences of Metal Dusting

The consequences of metal dusting carburisation and nitridation are severe, particularly in high-temperature applications. The formation of brittle carbides and nitrides leads to:

Reduced mechanical strength
Increased susceptibility to cracking
Accelerated corrosion

li>Premature component failure

These effects can have devastating impacts on industries such as petrochemical processing, power generation, and aerospace, where materials are exposed to harsh environments.

Mitigation Strategies

Material Selection

The judicious selection of materials is crucial in mitigating metal dusting carburisation and nitridation. Alloys with high chromium and/or aluminium content have been found to exhibit enhanced resistance to these reactions due to the formation of protective oxide layers.

Process Control

Optimising process parameters can effectively reduce the risk of metal dusting. Maintaining low carbon and nitrogen levels in process gases, controlling temperature, and minimising exposure time are key strategies.

Protective Coatings

Applying protective coatings to metallic surfaces provides a physical barrier against carburising and nitriding atmospheres. Coatings based on chromium, aluminium, or silicon have shown promising results in mitigating these reactions.

Applications and Case Studies

Petrochemical Processing

In petrochemical plants, metal dusting is a major concern for components exposed to hydrocarbon streams containing hydrogen and carbon monoxide. Mitigation strategies such as the use of resistant alloys and protective coatings have been successfully implemented to extend equipment lifespans.

Power Generation

In power plants, metal dusting can affect gas turbine components exposed to high-temperature combustion gases. Advanced coating technologies and process optimisation have been employed to combat this issue, ensuring reliable operation and extended maintenance intervals.

Metal dusting carburisation and nitridation are complex phenomena that pose significant challenges in diverse industrial applications. By understanding the mechanisms and consequences of these reactions, engineers and researchers can develop effective mitigation strategies to protect metallic components and ensure optimal performance.

This article has provided a comprehensive overview of metal dusting carburisation and nitridation, empowering readers with the knowledge to address these challenges and safeguard the longevity of their applications.

References

Hucke, M., & Grabke, H. J. (2005). Metal dusting corrosion in coal gasification and cracking processes. Materials and Corrosion, 56(7),479-486.
Yuhara, S., & Okabe, N. (2012). Nitridation and dusting mechanism of ferritic stainless steels in NH3-H2 atmospheres. Corrosion Science, 56(0),116-125.
Rahmel, A., & Grabke, H. J. (1995). Carburisation and nitridation of heat-resistant materials in high-temperature gases. Materials and Corrosion, 46(11),852-866.
Shida, Y., & Matsunaga, K. (2016). Metal dusting corrosion of nickel-based superalloys in CO/CO2-H2S atmospheres. Materials Transactions, 57(12),2158-2163.
European Federation of Corrosion. (2016). Metal Dusting Carburisation and Nitridation. http://www.efcweb.org/publications/books-and-proceedings/