METAL SURFACE TREATMENTS FOR CORROSION RESISTANCE

The corrosive deterioration of metal surfaces incurs a great cost to the worldwide economy. Accordingly, there have been many research efforts devoted to understanding the surface chemistry behind these reactions. As we have already seen, this has led to the development of a number of useful alloys that are sufficiently resistant to corrosion - through spontaneous formation of protective oxide layers. However, for other less resistant metals such as carbon steels, a protective layer must be postdeposited onto a metal surface in an effort to prevent corrosion. In this section. 

For carbonaceous gases such as CO and CH4 at relatively high temperatures (ca. 800°C), carburization of steel surfaces takes place in the form of brittle interstitial carbides that may cause surface cracking. Cementite may also form on the surface of steel since its melting point is lower than the underlying metal, it may cause melting of the steel surface that is subsequently eroded by the gas stream. 

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