Abstract:
A method of forming an oxide coating for reducing the accumulation of radioactive species on a metallic surface exposed to fluids containing charged particles is disclosed. The method includes preparing an aqueous colloidal suspension containing about 0.5 to about 35 weight percent of nanoparticles that contain at least one of titania and zirconia, and about 0.1% to about 10% 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (C7H14O5) or polyfluorosufonic acid in water, depositing the aqueous colloidal suspension on the metallic surface, drying the aqueous colloidal suspension to form a green coating, and then heating the green coating to a temperature of up to 500° C. to densify the green coating to form an oxide coating having a zeta potential less than or equal to the electrical polarity of the charged particles so as to minimize deposition of the charged particles on the metallic surface. The nanoparticles have a diameter of up to about 200 nanometers.
Abstract:
A method for mitigating stress corrosion cracking in high temperature water includes introducing catalytic nanoparticles and dielectric nanoparticles to the high temperature water in an amount effective to reduce a electrochemical corrosion potential of the high temperature water.
Abstract:
A method for reducing in situ the electrochemical corrosion potential and susceptibility to stress corrosion cracking of a nickel-base alloy and boiling water nuclear reactor components formed therefrom when in contact with high temperature water. The method comprises the steps of: adding a metal hydride to the high temperature water; dissociating the metal hydride in the high temperature water to form a metal and at least one hydrogen ion; and reducing the concentration of the oxidizing species by reacting the hydrogen ions with an oxidizing species, thereby reducing in situ the electrochemical corrosion potential of the nickel-base alloy. The method may further include the steps of reacting the metal with oxygen present in the high temperature water to form an insoluble oxide and incorporating the metal into the surface of the nickel-base alloy, thereby reducing the electrical conductivity of the surface of the nickel-base alloy. A nickel-base alloy component having a reduced electrochemical corrosion potential is also disclosed.
Abstract:
Method for reducing in situ the electrochemical corrosion potential and susceptibility to stress corrosion cracking of a nickel-base alloy and boiling water nuclear reactor components formed therefrom when in contact with high temperature water. The method comprises the steps of: adding a metal hydride to the high temperature water; dissociating the metal hydride in the high temperature water to form a metal and at least one hydrogen ion; and reducing the concentration of the oxidizing species by reacting the hydrogen ions with an oxidizing species, thereby reducing in situ the electrochemical corrosion potential of the nickel-base alloy. The method may further include the steps of reacting the metal with oxygen present in the high temperature water to form an insoluble oxide and incorporating the metal into the surface of the nickel-base alloy, thereby reducing the electrical conductivity of the surface of the nickel-base alloy. A nickel-base alloy component having a reduced electrochemical corrosion potential is also disclosed.
Abstract:
A method for mitigating crack initiation and propagation on the surface of metal components in a water-cooled nuclear reactor. A metal coating having an electrically insulating outer layer is applied on the surfaces of IGSCC-susceptible reactor components. The preferred metal coating is a zirconium alloy with a zirconia outer layer. The presence of an electrically insulating layer on the surface of the metal components shifts the corrosion potential in the negative direction without the addition of hydrogen and in the absence of a noble metal catalyst. Corrosion potentials.ltoreq.-0.5 V.sub.SHE can be achieved even at high oxidant concentrations and in the absence of hydrogen.
Abstract:
A method for improving the performance and longevity of coatings of metal deposited from aqueous solutions of inorganic, organic or oraganometallic metal compounds. The method involves co-deposition of noble metal or corrosion-inhibiting non-noble metal during growth of oxide film on a component made of alloy, e.g., stainless steels and nickel-based alloys. The result is a metal-doped oxide film having a relatively longer life in the reactor operating environment. In particular, incorporation of palladium into the film provides greatly increased catalytic life as compared to palladium coatings which lie on the oxide surface.