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Formation of an amorphous Al2Si2O5 layer on a steel pipe surface, after granite–dry steam interaction in the presence of copper, has been determined by XRD analysis and SEM (with energy dispersive X‐ray microanalysis). Kinetic data indicate high‐protective properties of the Al2Si2O5 layer, which formed a three‐dimension substrate ∼5 μm thick, after 100 h exposure.

Ô¼â£öCÝìpºmçÛǡܬ_m«»ÍoRè¹EInna R. KorablovaESergiy F. KorablovThis work focused on granite\SUS pipe\dry steam interaction in the presence of copper. Three types of hydrothermal experiments were conducted: 1) SUSCugranite, 2) SUSCu, 3) SUSgranite. It was found that a high protective amorphous AlSi 1.6 O 4 layer (thickness about 5 mm) formed on the supporting pipe sur face only in the case of SUSCugranite interaction. The formed layer was characterized by Xray diraction (XRD) techniques and scanning electron microscopy (SEM) equipped with an enrgy dispersive Xray (EDX) device. According to kinetics data this layer was conrmed to have highly protective properties.

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We have observed that a highly protective amorphous aluminum silicate layer on a steel surface was formed after granite–dry steam interaction in the presence of a copper plate near the critical point of water. In this process, the mass transfer of aluminum and silicon species from the granite to the steel surface takes place after copper was transferred to the granite surface. The rate of this process is accelerated by the presence of copper on the granite surface. At present, we have determined the effect of transferred copper species on the weight loss of granite in dry steam with different ratios of O2 and N2. It was also found that transferred copper species at a low O2 level promote the weight loss of granite. Four types of experiments were conducted at low O2 ratios in different‐density steam: (1) steel–steam, (2) steel–Cu–steam, (3) steel–granite–steam, and (4) steel–granite–Cu–steam. It was established that an aluminum silicate film formed on the steel surface only at the steel–granite–Cu–dry steam interaction. The formed film was characterized by scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy and by X‐ray photoelectron spectroscopy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)