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Role and efforts of T3C in corrosion economics

Description: The basic purpose of T3C activity is to show how to acquire specific corrosion cost information so that overall costs for doing business can be reduced. The scope of T3C is to accumulate data, appraise methods, develop recommended practices, promote knowledge and communicate relative to the economic evaluation of corrosion and counter corrosion techniques.
Date: November 1, 1979
Creator: Perrigo, L.D.; Appleman, B.R.; Pamer, R.I. & Thompson, J.L.
Partner: UNT Libraries Government Documents Department

Experimental application of design principles in corrosion research

Description: Experimental design criteria for corrosion investigations are based on established principles for systems that have uniform, or nearly uniform, corrosive attack. Scale-up or scale-down may be accomplished by proper use of dimensionless groups that measure the relative importance of interfacial kinetics, solution conductivity, and mass transfer. These principles have been applied to different fields of corrosion which include materials selection testing and protection; and to a specific corrosion problem involving attack of a substrate through holes in a protective overplate.
Date: January 1, 1977
Creator: Smyrl, W.H. & Pohlman, S.L.
Partner: UNT Libraries Government Documents Department

Electrochemical aspects of stress-corrosion cracking in. cap alpha. -brass

Description: This paper considers a number of aspects of the stress-corrosion cracking of brass from the point of view of the localized electrochemical processes occurring at the tip of a propagating crack. The principal system examined is the intergranular SCC of 70-30 brass in near-neutral ammoniacal solutions, for which a detailed mechanism is developed. In addition, the effects of nitrite ions in promoting SCC of both brass and copper are considered.
Date: January 1, 1981
Creator: Burstein, G T & Newman, R C
Partner: UNT Libraries Government Documents Department

Lithium compatibility research: status and requirements for ferrous materials

Description: A brief historical review and a description of the present status of the knowledge accumulated on lithium-ferrous alloy corrosion research are presented and discussed. The effects of various parameters are discussed and the future requirements of lithium corrosion research are presented and discussed.
Date: January 1, 1978
Creator: Selle, J.E. & Olson, D.L.
Partner: UNT Libraries Government Documents Department

Uranium oxidation: characterization of oxides formed by reaction with water

Description: Three different uranium oxide samples have been characterized with respect to the different preparation techniques. Results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. 27 figures.
Date: April 27, 1983
Creator: Fuller, E.L. Jr.; Smyrl, N.R.; Condon, J.B. & Eager, M.H.
Partner: UNT Libraries Government Documents Department

A study of the inhibition of pitting of aluminum by chromate

Description: The location of chromate activity during the pitting corrosion of aluminum has been studied. Scanning vibrating probe technique monitored the current densities above cathodic and anodic sites and SIMS was used to determine the location of chromium reduction products. Products deposited preferentially on cathodes but chromates dramatically inhibited the anodic pitting processes. 8 refs., 3 figs.
Date: January 1, 1991
Creator: Hawkins, J.; Thompson, G.E.; Wood, G.C. (University of Manchester Inst. of Science and Technology (UK). Corrosion and Protection Centre) & Isaacs, H.S. (Brookhaven National Lab., Upton, NY (USA))
Partner: UNT Libraries Government Documents Department

Initial stages of high temperature metal oxidation

Description: The application of XPS and UPS to the study of the initial stages of high temperature (> 350/sup 0/C) electrochemical oxidation of iron and nickel is discussed. In the high temperature experiments, iron and nickel electrodes were electrochemically oxidized in contact with a solid oxide electrolyte in the uhv system. The great advantages of this technique are that the oxygen activity at the interface may be precisely controlled and the ability to run the reactions in uhv allows the simultaneous observation of the reactions by XPS.
Date: January 1, 1981
Creator: Yang, C.Y. & O'Grady, W.E.
Partner: UNT Libraries Government Documents Department

Modification of the hydriding of uranium using ion implantation

Description: The hydriding of depleted uranium at 76 Torr hydrogen and 130/sup 0/C has been significantly reduced by implantation of oxygen ions. The high-dose implanted specimens had incubation times for the initiation of the reaction after exposure to hydrogen that exceeded those of the nonimplanted specimens by more than a factor of eight. Furthermore, the nonimplanted specimens consumed enough hydrogen to cause macroscopic flaking of essentially the entire surface in times much less than the incubation time for the high-dose implanted specimens. In contrast, the ion-implanted specimens reacted only at isolated spots with the major fraction of the surface area unaffected by the hydrogen exposure.
Date: November 4, 1983
Creator: Musket, R.G.; Robinson-Weis, G. & Patterson, R.G.
Partner: UNT Libraries Government Documents Department

Nucleation of copper during supersonic expansion

Description: Nucleation of copper vapor during gas expansion in a supersonic nozzle is investigated. Time scales for nucleation delay and supersaturation doubling are considered in establishing the need for non-steady state nucleation theory. A population balance model is constructed for tracking the size spectrum of stable clusters formed from self nucleation and exposed to supersaturated gas. It is found that at average cooling rates exceeding 10{sup 7} K/s, copper vapor exists in a highly nonequilibrium concentration at the nozzle exit. Copper condensation is severely limited by the nucleation kinetics and the available residence time. It is influenced by the monomer concentration and the nozzle exit pressure and temperature. The size spectrum of stable clusters is dominated by small clusters containing fewer than fifteen molecules. Nucleation persists throughout the expansion process because of the inability of the vapor condensation processes to relieve supersaturation buildup due to rapid gas cooling. Nucleation rate is sensitive to the surface energy of the clusters corresponding to the critical size. Monte-Carlo simulations of admissible cluster configurations are recommended for determining statistically-averaged surface energies of clusters containing two-to-twenty molecules. 7 refs., 10 figs., 6 tabs.
Date: December 1, 1989
Creator: Ahluwalia, R.K. & Im, K.H.
Partner: UNT Libraries Government Documents Department

The use of a scanning electrochemicl impedance spectroscopy technique to investigate localized corrosion

Description: Recently, the authors have proposed a method for generating local electrochemical impedance maps of electrodes. In this technique impedance maps, at each frequency of interest, are generated by measuring the ratio of ac solution current density, very near the electrode, to the applied potential is measured as a function of position. A review of this method, the results from two model systems, which demonstrate that this technique may be used to generate quantitative data, and its use to investigate aluminum alloys will be presented. 7 refs., 3 figs.
Date: January 1, 1991
Creator: Lillard, R.S. (Johns Hopkins Univ., Baltimore, MD (USA)); Moran, P.J. (Naval Academy, Annapolis, MD (USA). Dept. of Mechanical Engineering) & Isaacs, H.S. (Brookhaven National Lab., Upton, NY (USA))
Partner: UNT Libraries Government Documents Department

Scanning reference electrode techniques in localized corrosion

Description: The principles, advantages, and implementations of scanning reference electrode techniques are reviewed. Data related to pitting, intergranular corrosion, welds and stress corrosion cracking are presented. The technique locates the position of localized corrosion and can be used to monitor the development of corrosion and changes in the corrosion rate under a wide range of conditions.
Date: April 1, 1979
Creator: Isaacs, H.S. & Vyas, B.
Partner: UNT Libraries Government Documents Department

XANES (X-ray Absorption Near Edge Structure) investigation of cerium as an inhibitor for Al alloys

Description: Cerium ions are under investigation as possible replacements for toxic chromates. The use of cerium ions as corrosion inhibitors for aluminum alloys is investigated using XANES (x-ray absorption near edge structure). On immersion in a dilute solution of cerium ions, cerium is incorporated into the oxide films on aluminum alloys in either the 3- or 4-valent state depending upon the alloy and on the surface preparation. 7 refs., 2 figs.
Date: January 1, 1991
Creator: Davenport, A.J.; Isaacs, H.S. (Brookhaven National Lab., Upton, NY (USA)) & Kendig, M.W. (Rockwell International Corp., Thousand Oaks, CA (USA). Science Center)
Partner: UNT Libraries Government Documents Department

Sodium and lithium corrosion in molybdenum heat pipes

Description: Sodium and lithium corrosin in molybdenum heat pipes has been shown to be impurity dependent rather than solubility dependent. Impurities represent the major contributors to corrosion in the heat pipes tested. Our experiments have shown no evidence of direct solution of molybdenum by either sodium or lithium. Analysis has suggested that a critical concentration of impurities is required to initiate corrosion. Thus it appears that corrosion in Mo/Na and Mo/Li heat pipes can be controlled if impurity concentration can be limited by removal of impurities from the working fluid and heat pipe components prior to operation or by internal gettering during operation.
Date: January 1, 1984
Creator: Lundberg, L.B. & Merrigan, M.A.
Partner: UNT Libraries Government Documents Department

Modeled heating and surface erosion comparing motile (gas borne) and stationary (surface coating) inert particle additives

Description: The unsteady, non-similar, chemically reactive, turbulent boundary layer equations are modified for gas plus dispersed solid particle mixtures, for gas phase turbulent combustion reactions and for heterogeneous gas-solid surface erosive reactions. The exterior (ballistic core) edge boundary conditions for the solutions are modified to include dispersed particle influences on core propellant combustion-generated turbulence levels, combustion reactants and products, and reaction-induced, non-isentropic mixture states. The wall surface (in this study it is always steel) is considered either bare or coated with a fixed particle coating which is conceptually non-reactive, insulative, and non-ablative. Two families of solutions are compared. These correspond to: (1) consideration of gas-borne, free-slip, almost spontaneously mobile (motile) solid particle additives which influence the turbulent heat transfer at the uncoated steel surface and, in contrast, (2) consideration of particle-free, gas phase turbulent heat transfer to the insulated surface coated by stationary particles. Significant differences in erosive heat transfer are found in comparing the two families of solutions over a substantial range of interior ballistic flow conditions. The most effective influences on reducing erosive heat transfer appear to favor mobile, gas-borne particle additives.
Date: September 27, 1982
Creator: Buckingham, A.C. & Siekhaus, W.J.
Partner: UNT Libraries Government Documents Department

Potential transmission and transients during corrosion: Applications to corrosion monitoring

Description: The transmission of potential along a passive metal/electrolyte interface, which is important in corrosion monitoring, has been considered for transitory and sustained corrosion processes. The observed signals are modified and delayed by the passive surface. Using a transmission line as the equivalent circuit of a pipe and incorporating the impedance characteristics of the passive-metal/solution interface, enabled an analysis of the effectiveness of corrosion monitoring methods to be carried out.
Date: January 1, 1992
Creator: Isaacs, H.S. & Cho, Jeong-Hwan.
Partner: UNT Libraries Government Documents Department

Investigations of intermetallic alloy hydriding mechanisms. Annual progress report, July 1, 1977--April 30, 1978

Description: Measurements of hydridation of thin films are described. Film deposition by rf sputtering is discussed and studies of microstructure changes due to hydridation are presented. The influence of factors such as alloy composition, microstructural details, surface layers or contaminants and physical properties on hydriding characteristics such as the kinetics of hydrogen absorption and desorption, quantities absorbed, heats of hydriding and the effects of long-term absorption-desorption cycling were studied. (GHT)
Date: April 30, 1978
Creator: Livesay, B.R. & Larsen, J.W.
Partner: UNT Libraries Government Documents Department

Titanium-potassium heat pipe corrosion studies

Description: An experimental study of the susceptibility of wickless titanium/potassium heat pipes to corrosive attack has been conducted in vacuo at 800/sup 0/K for 6511h and at 900/sup 0/K for 4797h without failure or degradation. Some movement of carbon, nitrogen and oxygen was observed in the titanium container tube, but no evidence of attack could be detected in metallographic cross sections of samples taken along the length of the heat pipes. The lack of observable attack of titanium by potassium under these conditions refutes previous reports of Ti-K incompatibility.
Date: July 1, 1984
Creator: Lundberg, L.B.
Partner: UNT Libraries Government Documents Department

Oxidation mechanisms for alloys in single-oxidant gases

Description: Scales formed on alloys invariably contain the alloy constituents in a ratio different from that in the alloy, owing to the differing thermodynamic tendencies of the alloy components to react with the oxidant and to differences in diffusion rates in scale and alloy phases. This complex interrelationship between transport rates and the thermodynamics of the alloy-oxidant system can be analyzed using multicomponent diffusion theory when transport-controlled growth of single or multi-layered scales occurs. In particular, the superimposition of the diffusion data on an isothermal section of the appropriate phase diagram indicates the likely morphologies of the reaction products, including the sequence of phases found in the scale, the occurrence of internal oxidation and the development of an irregular metal/scale interface. The scale morphologies on alloys are also time-dependent: there is an initial transient stage, a steady state period, and a final breakdown, the latter often related to mechanical influences such as scale adherence, spallation, thermal or mechanical stresses and void formation. Mechanical influences have a more devastating effect in alloy oxidation due to the changes in alloy surface composition during the steady state period.
Date: March 1, 1981
Creator: Whittle, D.P.
Partner: UNT Libraries Government Documents Department

Erosion--corrosion

Description: The deterioration of materials by corrosion or erosion by itself presents a formidable problem and for this reason investigators have studied these two phenomena independently. In fact, there are very few systematic studies on E-C and the majority of references mention it only in passing. In most real systems, however, the two destructive processes take place simultaneously, hence the purpose of this review is to present the various interactions between the chemical and mechanical agents leading to accelerated degradation of the material. The papers cited in the review are those that lead to a better understanding of the process involved in the accelerated rate of material loss under E-C conditions.
Date: January 1, 1978
Creator: Vyas, B.
Partner: UNT Libraries Government Documents Department

Evaluation of the current status of hydrogen embrittlement and stress-corrosion cracking in steels

Description: A review of recent studies on hydrogen embrittlement and stress-corrosion cracking in steels shows there are several critical areas where data is either ambiguous, contradictory, or non-existent. A relationship exists between impurity segregation and hydrogen embrittlement effects but it is not known if the impurities sensitize a preferred crack path for hydrogen-induced failure or if impurity and hydrogen effects are additive. Furthermore, grain boundary impurities may enhance susceptibility through interactions with some environments. Some studies show that an increase in grain size increases susceptibility; at least one study shows an opposite effect. Recent work also shows that fracture initiates at different locations for external and internal hydrogen environments. How this influences susceptibility is unknown.
Date: December 1, 1981
Creator: Moody, N.R.
Partner: UNT Libraries Government Documents Department

Dissolution of aluminium oxide as a regulating factor in aqueous aluminum corrosion

Description: The solubility of aluminum corrosion product in contact with metallic aluminum in deionized water has been determined over the range 80 to 350/sup 0/C. Evidence is presented to show that oxide dissolution results in the formation of a porous oxide on aluminum exposed in refreshed dynamic systems. Dynamic corrosion rate data have been analyzed on the basis of parabolic film growth and a linear oxide degradation process acting simultaneously on the system. The degradation process has been shown to be a function of refreshment rate.
Date: August 31, 1959
Creator: Dillon, R.L.
Partner: UNT Libraries Government Documents Department

Microbiologically mediated reduction in the pitting of mild steel overlaid with plywood

Description: Laboratory experiments were conducted to determine the role of microorganisms in the pitting of mild steel flooring, which had been overlaid with plywood. The experimental setups consisted of 4.8 mm (3/16 in.) mild steel plates covered with 12.7 mm (1/2 in.) thick pieces of plywood which were exposed to several different aqueous media supplemented with various combinations of a soil suspension and selected inorganic and organic compounds. Half of the replicate metal-wood-water setups were sterilized and aseptically maintained during incubation after which they were checked for the presence of viable microorganisms and pitting of the mild steel. Results of the first set of experiments showed that pitting of the mild steel specimens in many of these setups occurred after a reasonably short incubation period (3 to 6 months). However, the method used to exclude microorganisms by sterilizing the components separately was unsuccessful. In a second set of experiments, setups were sterilized by exposure to gamma irradiation after they had been assembled. The sterilized setups remained sterile after incubation while those which were not originally sterile still contained viable microorganisms. Pitting of the mild steel specimens was more severe when they were exposed to sterile conditions than when viable microorganisms were present. These experiments showed that while microorganisms are known to enhance corrosion processes in some circumstances, their presence can reduce corrosion in others.
Date: January 1, 1984
Creator: Soracco, R. J.; Berger, L. R.; Berger, J. A.; Mayack, L. A.; Pope, D. H. & Wilde, E. W.
Partner: UNT Libraries Government Documents Department