Patent ID: 7449101

Claim:
A method of reducing corrosion of a metal material on a metal material surface to be exposed to hot water in a power plant, comprising: coating or adhering an n-type semiconductor substance having conductivity for generating an anode current by thermal excitation in the absence of irradiation of light on the metal material surface to be exposed to hot water in a power plant, and exposing the metal surface to water having a temperature of 150° C. or more, wherein the n-type semiconductor is at least one compound selected from a group consisting of a TiO 2 , a PbO, a BaTiO 3 , a Bi 2 O 3 , a ZnO, a WO 3 , an SrTiO 3 , an Fe 2 O 3 , an FeTiO 3 , a KTaO 3 , an MnTiO 3 , an SnO 2 , a ZrO 2 , a CeO 2 and an In 2 O 3 .