Metal dusting oxide scale protection

The most common failures are associated with oxidation, carburization and metal dusting, sulfidation, chlorination, and nitridation. The most common high-temperature degradation mode is oxidation, and the protection against oxidation, in general, is given by the formation of a chromium oxide scale. The presence of a small amount of aluminum or silicon in the alloy may improve the resistance against oxidation of a... 

The process also requires additions of chloriding agents now and then their effect was investigated using trichlorethylene (TCE). The presence of TCE enhances the metal dusting attack markedly, most probably due to destruction of protective oxide scales. Upon sufficient H2S addition, this effect can be eliminated, but again the additions of H2S would have to be too high at temperatures >620 °C. 

Current methods of protection against metal dusting are either direeted to the process conditions - temperature, gas composition and sulphur content -or the development of a dense adherent oxide layer on the surface of the alloy by selective oxidation [5, 10-12]. This is done by the addition of chromium, and to a lesser extent aluminium and silicon. However, carbon can still dissolve in the base metal via defects in the oxide scale, meaning that metal dusting is not stopped, but slowed and delayed. 

Nickel alloys containing Cu, even though they did not have any oxide scales to protect against CO gas, were demonstrated to improve the metal dusting... 

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