Typical materials for applications in high-temperature, high-pressure aqueous solutions are stainless steels, nickel-base alloys, titanium, tantalum, noble metals, or ceramics. Under these conditions, these materials are often severely attacked, especially in the presence of acids, salts, or gases. Corrosion phenomena in high-temperature aqueous solutions are mainly influenced by the following factors: dissociation of acids, salts, and bases, the solubility of gases, the solubilities of corrosion products, and the stability of the protecting oxide layers. The influences of these factors on the corrosion, together with literature data of dissociation constants and solubilities of oxides, are reviewed in this paper. A recommendation is given for the application of possible reactor materials for oxidizing high-temperature aqueous systems in the presence of different inorganic species.

Factors controlling corrosion in high-temperature aqueous solutions: a contribution to the dissociation and solubility data influencing corrosion processes

Physicochemical and catalytic properties of the system chromium oxides-oxygen-water

Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides.

The oxide of chromium (IV), Cr02, is a highly interesting compound for materials investigation in that it is ferromagnetic at room temperature and a good electrical conductor. The Curie temperature is 118°C, and the material can readily be demagnetized with little energy input. The electrical conductivity of this black compound is quite high for an oxide; it even rivals some of the metal conductors such as Mn and Gd at roomtemperature. Thls review describes procedures for preparing Cr02, presents its chemical and physical properties including the modifications observed with metal-ion substitutions, and discusses the reactions of Cr02 with other metal oxides together with the physical properties of the ternary products containing tetravalent chromium.

A. W. Laubengayer

Papers

New Crystalline Phases in the System Chromium(III) Oxide—Water1