High-temperature corrosion metal dusting

Lai, G. Y., Carburization and Metal Dusting, High Temperature Corrosion of Engineering Alloys, ASM International, Materials Park, OH, 1990, pp. 47-72. 

T. A. Ramanarayanan and C. M. Chun, Chapter 6 Metal Dusting Corrosion of Metals and Alloys, New Development in High Temperature Corrosion and Protection of Materials, Ed. W. Gao and Z. Li, Woodhead Publishing Ltd., Cambridge, UK p.80-116 (2008). 

Ramanarayanan TA, Chun CM. Metal dusting corrosion of metals and alloys. In Gao W, Li Z, editors. Developments in high temperature corrosion and protection of materials. Cambridge - UK Woodhead Publishing 2008. p. 80-116 [chapter 5]. 

Accelerated deterioration of metals in carbonaceous gases at elevated temperatures to form a dust-fike corrosion product a unique form of high-temperature corrosion that forms a dust-hke corrosion product and sometimes develops hemispherical pits on a susceptible metal surface simultaneous carburization is generally observed. 

As was also indicated in this chapter the development of an understanding of the mechanisms is still in a dynamic phase as recently significant steps forward have been made in the areas of metal dusting and chlorine corrosion. This shows that high-temperature corrosion research despite all the invaluable achievements in the past is far from being a static situation and in addition to textbook knowledge it is necessary to follow the most recent literature in order to stay up-to-date in the field. 

Maleic Anhydride. The ACGIH threshold limit value in air for maleic anhydride is 0.25 ppm and the OSHA permissible exposure level (PEL) is also 0.25 ppm (181). Maleic anhydride is a corrosive irritant to eyes, skin, and mucous membranes. Pulmonary edema (collection of fluid in the lungs) can result from airborne exposure. Skin contact should be avoided by the use of mbber gloves. Dust respirators should be used when maleic anhydride dust is present. Maleic anhydride is combustible when exposed to heat or flame and can react vigorously on contact with oxidizers. The material reacts exothermically with water or steam. Violent decompositions of maleic anhydride can be catalyzed at high temperature by strong bases (sodium hydroxide, potassium hydroxide, calcium hydroxide, alkaU metals, and amines). Precaution should be taken during the manufacture and use of maleic anhydride to minimize the presence of basic materials. 

The formation of carbon over Ni, Fe, and Co has been extensively studied, both for catalytic applications " and for dusting or dry corrosion, the problem of pitting when steels are exposed to hydrocarbons at high temperatures. Recently, the properties of Ni for forming carbon have even been proposed for use in the manufacture of carbon nanofibers. The mechanism on each of these metals, shown diagrammatically in Figure 8a, involves deposition of a carbon source onto the metal surface, dissolution of the carbon into the bulk of the metal, and finally precipitation of carbon as a fiber... 

Corrosion protection-stoving enamels are produced upon pigmentation with zinc dust. These are utilized for the enameling of components which operate at high temperatures e.g. metal chimneys. 

In heat exchange reformers, special precautions must be taken to avoid corrosion. In such reformers the metal temperature is often high enough for metal dusting to occur and low enough for thermodynamic potential to exist. Special alloys or other techniques are needed to prevent metal dusting in these cases. This area is the subject of considerable research to widen the limits of operation to more severe operating conditions. 

High-temperature processes may induce several corrosion phenomena on the metallic substrate. High-temperatme oxidation may occm on the other surfaces of the reactors while this phenomenon may compete with carburization and metal dusting (MD) phenomena in the inner walls of the structured cataljdic devices. The latter phenomenon occurs in high-carbon-activity atmospheres as the ones resulting from reformate streams. 

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