Morphological study of 16-year patinas formed on copper in a wide range of atmospheric exposures

Long-term forecast of corrosion mass losses of technically important metals in various world regions using a power function

Bi-modal trends in the long-term corrosion of copper and high copper alloys

A brief review has been carried out on the performance of barrier materials for low-level radioactive wastes in seawater environments The environments include those for shallower coastal waters as well as the deep ocean (down to 3800 m) The review is mainly focused on metallic materials since they are the most common for seawater service and they have the largest data base Information from the literature is usually pertinent to shallower coastal locations, but there is a valuable source of corrosion data obtained from several studies of metallic specimens exposed to ocean-bed conditions In addition, the corrosion of carbon steel barriers has been evaluated for actual waste containers that were retrieved from previously-used disposal sites in the Atlantic and Pacific Oceans Of the metallic materials studied, carbon steel showed the least corrosion resistance Failure by non-uniform attack in a typical waste container could occur in as little as 25 y in some ocean environments ` Penetration by local attack, such as pitting and crevice corrosion resistance was also observed for more expensive materials such as low-alloy steels, stainless steels, titanium alloys, zirconium alloys, copper alloys, nickel alloys, aluminum alloys, and lead alloys

/pdf/corrosion-of-barrier-materials-in-seawater-environments-9ag4kl5pfg.pdf

Corrosion of barrier materials in seawater environments

Influence of seawater and its aerosols on copper patina composition

Cu and Cu alloys show weight losses in tropical water from 1.4 to 2 times that in temperate waters; tropical marine atmosphere also cause higher weight losses. Corrosion of commercially pure Cu for 16 years in tropical sea water was approximately proportional to Ct 1/2 C isa constant and t is time of exposure). Corrosion-time functions for the other high Cu and alpha-phase Cu-Zn alloys were generally curvilinear for the first 4-8 years exposures. Extrapolation of the curves shows the lack of reliability of the short-term secant rates. In the various tropical environments, 5% Al bronze had the best over-all corrosion resistance. alpha-Phase Cu-Zn corroded slightly faster than Cu in fresh water and somewhat less than Cu in other environments. The 60-40 alpha + beta brasses, with the exception of Mn bronze in fresh water, corroded considerable more than Cu in underwater exposures. Heavy dezincification occurred in the alpha + beta brasses in sea water. Moderate dezincification was evident in the duplex brasses in fresh water and marine atmosphere exposures. Small additions of As, Sn, and Mn were ineffective in inhibiting marine dezincification of high brasses. Tensile data generally show weight losses for the high Cu Alloy, and heavy dezincification in the duplex brasses with penetrations 2.2 to 5.5 times that shown by weight logs for the sea-water exposures. Corrosion of phosphor bronze and naval brass was galvanically accelerated 42 and 24% when coupled with 1/7 area strips of type 316 stainless steel. Efficient cathodic protection of bronze and brass was provided by C Steel anodes for periods of 8-12 years. Cu and its alloys showed varying fouling resistance in the bioactive tropical waters. Marine fouling collected directly on Cu panels when the corrosion rate of the Cu was too low to provide an effective Cu ion concentration. Galvanically protected Cu metals, including dezincified surfaces, were moderately to heavily covered at the 2 year inspection. Plates of Cu and high-Cu alloys showed decreasing fouling resistance with exposure time and all were heavily covered at 16 years. Corrosion of all Cu metals was very low in the tropical atmosphere, and they are considered excellent for this environment. All bronze and the Cu Zn alloys cored linearly with time after 1 or 2 years exposure in the atmosphere.

Charles R. Scuthwell

Papers

Corrosion of metals in tropical environments. Copper and wrought copper alloys