689 Matching Results

Search Results

Advanced search parameters have been applied.

Corrosion tests of a heated wing utilizing an exhaust-gas-air mixture for ice prevention

Description: Report presenting an investigation of the exhaust of corrosive attack in an aluminum alloy wing employing an exhaust-gas-air mixture as a heating medium for ice prevention. There were no cases of structurally serious corrosion on either painted or plain specimens removed from the wing for detailed microscopic and metallurgic examination.
Date: January 1949
Creator: Holdaway, George H.
Partner: UNT Libraries Government Documents Department

Preliminary study of circulation in an apparatus suitable for determining corrosive effects of hot flowing liquids

Description: "A simple apparatus particularly applicable to the determination of the corrosive effects of flowing liquid metals on structural materials is described. In this apparatus, flow of the liquid medium at known velocities may be induced in toroidal shaped channels fabricated from the test structural material only, with no pump, valves, or flow meter required. A circulating velocity of 25 ft/sec has been obtained in preliminary tests and no basic limitation on increasing the speed was encountered" (p. 1).
Date: June 29, 1951
Creator: Desmon, Leland G. & Mosher, Don R.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of corrosion by molten sodium hydroxide flowing in tubes of AISI 347 stainless steel, Inconel, and nickel having average outer-wall temperatures of 1500 F and a circumferential temperature gradient of 20 F

Description: Experiments were performed with an apparatus suitable for determining corrosive effects of hot flowing liquids on various container materials. The investigation was conducted with molten sodium hydroxide flowing at a velocity of 15 feet per second. Extensive corrosion and mass trans Extensive corrosion and mass transfer to regions of reduced temperature was observed.
Date: March 1952
Creator: Mosher, Don R. & Desmon, Leland G.
Partner: UNT Libraries Government Documents Department

Failure of cooling tower LOB-CT-1

Description: Following the loss of cooling tower LOB-CT-1, an investigation was conducted to determine the cause and to develop precautions to prevent future cooling tower losses. This cooling tower, located in the office-building basement of the Clinton P. Anderson Los Alamos Meson Physics Facility (LAMPF), was shut down on October 29, 1973. Excessive use of chelate chemical was ludged to be the major factor involved in the high corrosion rates observed. A number of precautions are listed which should prevent further surprise'' corrosion problems. The precautions include precalculation of chemical additions, visual inspection, corrosion coupons, corrosion meters, and chemical analyses of operating conditions. (auth)
Date: March 1, 1974
Creator: Midkiff, W.S.
Partner: UNT Libraries Government Documents Department

CORROSION OF LEAD SHIELDING IN MODEL 9975 PACKAGE

Description: Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of organic materials used in the model 9975 package.[1] The experiments were completed within the framework of a parametric test matrix with variables of organic configuration, temperature, humidity and the effect of durations of exposure on the corrosion of lead in the 9975 package. The room temperature vulcanizing (RTV) sealant was the most corrosive organic species in the testing, followed by the polyvinyl acetate (PVAc) glue. The Celotex{copyright} material uniquely induced measurable corrosion only in situations with condensed water, and to a much lesser extent than the PVAc glue and RTV. The coupons exhibited faster corrosion at higher temperatures than at room temperatures. There was a particularly pronounced effect of condensed water as the coupons exposed in the cells with condensed water exhibited much higher corrosion rates. In the 9975 package, the PVAc glue was determined to be the most aggressive due to it's proximity in the design. The condition considered most representative of the package conditions is that of the coupon exposed to the Celotex{copyright}/glue organic exposed in the ambient humidity conditions. The corrosion rate of 2 mpy measured in the laboratory experiments for this condition is considered to be a bounding condition to the 9975 package conditions when the laboratory results are extrapolated to actual package conditions, and is recommended as a conservative estimate for package performance calculations.
Date: March 15, 2006
Creator: Subramanian, K
Partner: UNT Libraries Government Documents Department

The Electrochemical Behavior of Alloy in Extreme Chloride and Bitrate Environments

Description: Alloy 22 specimens were tested in high temperature (100 to 160 C), high concentration chloride and nitrate environments. Results of this study indicate that increasing nitrate to chloride ratio to 0.5 in these electrolytes increases resistance to localized breakdown and enhances repassivation. In these extreme environments, localized corrosion occurred by pitting even though specimens were tested using artificial crevice formers. Open circuit (E{sub corr}), breakdown and repassivation potentials all increase, and pitting morphology changes as nitrate to chloride ratio increases from 0.05 and 0.15 to 0.5. Results also indicate that increasing the temperature from 100 to 160 C increases E{sub corr} values, while breakdown potentials and repassivation potentials peak at 130 C for the 0.5 nitrate to chloride ratio electrolytes.
Date: July 27, 2006
Creator: Etien, R.A.; Gordon, S.R. & Ilevbare, G.O.
Partner: UNT Libraries Government Documents Department

A ceramographic evaluation of chromia refractories corroded by slag

Description: This paper describes the ceramographic preparation of Cr{sub 2}O{sub 3}-Al{sub 2}O{sub 3} refractory bricks and subsequent microstructural analysis to determine the corrosive effects of molten slag. The porous and friable nature of the brick, especially after exposure to the slag or its individual components, presented some problems in the preparation.
Date: January 1, 2001
Creator: Hunt, Alton H. & Chinn, Richard E.
Partner: UNT Libraries Government Documents Department

Comparison of Ceramic, Metal and Polymer Crevice Formers on the Crevice Corrosopn Behavior of Ni-CR-Mo Alloy C22

Description: A necessary condition for crevice corrosion is that a crevice former create a sufficiently tight, restricted geometry on the metal surface to support the development of critical crevice chemistry. Crevice corrosion is affected by the crevice geometry (tightness) and the properties of the crevice former. The objective of this study is to determine the effect of the crevice former material on the evolution of localized corrosion-damage. A standard crevice corrosion test method is modified by (a) the use of ceramic, metal or polymer materials as the crevice former and (b) the variation of size and shape of the crevice. This study focuses on the post initiation stage of crevice corrosion and addresses factors that may limit the initiation of localized corrosion and also slow or stop the continued propagation of corrosion. Controlled crevice corrosion tests are performed under aggressive, accelerated conditions on Ni-Cr-Mo alloy C-22 and other alloys for comparison. Multiple techniques are used to examine the crevice corrosion damage evolution. Current measurements during the test provide a direct measure of the corrosion rate and indicate the initiation and any stifling or arrest. The localized corrosion is found to be stifled or arrested under several test conditions. The corrosion damage volume and profile are quantitatively measured with optical and SEM 3D reconstruction methods. Analysis by SEMIEDS, XPS and AES show that the corrosion products within the damaged crevice area are enriched in W, Mo, 0 , while being depleted in Cr, Ni, Fe. The results on C-22, SS3 16 and other alloys show that a PTFE tape covered ceramic was the most active crevice former, solid polymer crevice formers (PTFE or Kel-F) are less active, while no distinguishable crevice corrosion was observed with a ceramic material only as the crevice former in direct contact with the metal. The affects are ...
Date: May 8, 2006
Creator: Shan, X. & Payer, J.H.
Partner: UNT Libraries Government Documents Department

Long-Term Corrosion Behavior of Alloy 22 in 5M CaCl2 at 120 C

Description: In conditions where tight crevices exist in hot chloride containing solutions Alloy 22 may suffer crevice corrosion. The occurrence (or not) of crevice corrosion in a given environment (e.g, salt concentration and temperature), is governed by the values of the critical potential (E{sub crit}) for crevice corrosion and the corrosion potential (E{sub corr}). This paper discusses the evolution of E{sub corr} and corrosion rate (CR) of creviced Alloy 22 specimens in 5 M calcium chloride (CaCl{sub 2}) at 120 C. Tested specimens included non-creviced rods and multiple creviced assemblies (MCA) both non-welded (wrought) and welded. Results show that Alloy 22 suffers crevice corrosion under the open circuit conditions in the aerated hot CaCl{sub 2} brine. However, after more than a year of immersion the propagation of crevice corrosion was not significant. The general corrosion rate decreased or remained unchanged as the immersion time increased. For rods and MCA specimens, the corrosion rate was lower than 100 nm/year after more than a year immersion time.
Date: May 8, 2006
Creator: Estill, J.C.; Hust, G.A.; Evans, K.J.; Stuart, M.L. & Rebak, R.B.
Partner: UNT Libraries Government Documents Department

Corrosion studies in plutonium--nitric--hydrofluoric solutions

Description: Several alloys were evaluated as possible construction material in chemical processing equipment for plutonium at Rocky Flats. Corrosion studies were made of these alloys in solutions obtained from a production storage tank. The principal components of these solutions were RNO/sub 3/, HF, and Pu. Results showed relative concentrations of these components can significantly affect corrosion rates. Of the alloys tested, lnconel 690 exhibited the lowest corrosion rates in the process solutions. E-Brite 26-1 also showed corrosion resistance greater than 304L stainless steel. (auth)
Date: February 1, 1974
Creator: Terada, K.; Macki, J. M.; Dringman, M. R. & Cash, D. L.
Partner: UNT Libraries Government Documents Department

Corrosion of beryllium exposed to celotex and water

Description: Celotex is a commercial rigid cellulose fiberboard product primarily used in the building construction industry. Currently celotex is being used as a packing material in AL-R8 containers. Ion chromatography of celotex packing material at Lawrence Livermore National Laboratory (LLNL) has indicated that this material contains aggressive anions, including chloride, which may accelerate corrosion. It is well known that beryllium is susceptible to pitting corrosion when exposed to chloride containing environments. Levy noted pitting in beryllium at the open circuit potential when exposed to 0.1 M NaCl solution. This investigation attempts to evaluate the potential risk of accelerated beryllium corrosion from celotex and water which may occur naturally when celotex dust comes into contact with moisture from the atmosphere.
Date: December 1, 1997
Creator: Hill, M.A.; Butt, D.P. & Lillard, R.S.
Partner: UNT Libraries Government Documents Department

The effect of chromate concentration on the repassivation of corroding aluminum

Description: Current density maps of anodically polarized pure aluminum in chloride solutions were measured and the effect of chromate/dichromate buffer additions monitored. The higher the polarized potential the more chromate was required to repassivate the corroding surface. Small pits repassivated easily, crevice corrosion events were the last to repassivate. Open circuit potential measurements showed the presence of meta-stable pitting at chloride concentrations of 0.3M. The lifetime and magnitude of these metastable pits was reduced on the addition of 0.05M chromate buffer.
Date: February 9, 1999
Creator: Jeffcoate, C.S.; Isaacs, H.S.; Hawkins, J. & Thompson, G.E.
Partner: UNT Libraries Government Documents Department

Dissolution of Oxide Films on Aluminum in Near Neutral Solutions

Description: Simple linear potentiodynamic cycling measurements have been made on abraded pure Al in borate, chromate, phosphate, sulfate and nitrate solutions. In borate and chromate solutions the currents continued to decrease with each subsequent cycle. In phosphate dissolution of the oxide takes place producing repetitive repeat curves. The current variations in borate and chromate were simulated using a high field conduction oxide growth model. Including oxide dissolution in the model simulated the phosphate behavior. Results in sulfate and nitrate solutions were more complex. The behavior in the sulfate solution was attributed to effects of sulfate the oxide/solution interface.
Date: October 17, 1999
Creator: Isaacs, Hugh S.; Xu, Feng & Jeffcoate, Carrol S.
Partner: UNT Libraries Government Documents Department

Effects of smoke on functional circuits

Description: Nuclear power plants are converting to digital instrumentation and control systems; however, the effects of abnormal environments such as fire and smoke on such systems are not known. There are no standard tests for smoke, but previous smoke exposure tests at Sandia National Laboratories have shown that digital communications can be temporarily interrupted during a smoke exposure. Another concern is the long-term corrosion of metals exposed to the acidic gases produced by a cable fire. This report documents measurements of basic functional circuits during and up to 1 day after exposure to smoke created by burning cable insulation. Printed wiring boards were exposed to the smoke in an enclosed chamber for 1 hour. For high-resistance circuits, the smoke lowered the resistance of the surface of the board and caused the circuits to short during the exposure. These circuits recovered after the smoke was vented. For low-resistance circuits, the smoke caused their resistance to increase slightly. A polyurethane conformal coating substantially reduced the effects of smoke. A high-speed digital circuit was unaffected. A second experiment on different logic chip technologies showed that the critical shunt resistance that would cause failure was dependent on the chip technology and that the components used in the smoke exposures were some of the most smoke tolerant. The smoke densities in these tests were high enough to cause changes in high impedance (resistance) circuits during exposure, but did not affect most of the other circuits. Conformal coatings and the characteristics of chip technologies should be considered when designing circuitry for nuclear power plant safety systems, which must be highly reliable under a variety of operating and accident conditions. 10 refs., 34 figs., 18 tabs.
Date: October 1997
Creator: Tanaka, T. J.
Partner: UNT Libraries Government Documents Department

Corrosion of alloy 718 in a mercury thermal convection loop

Description: Two thermal convection loops (TCLs) fabricated from annealed alloy 718 continuously circulated mercury (Hg) with 1000 wppm gallium (Ga), respectively, for about 5000 h, duplicating previous TCL tests for annealed 316L. In each case, the maximum loop temperature was 305C, the minimum temperature was 242C, and the Hg flow rate was approximately 1.2 m/min. Unlike the 316L exposed to Hg, which above about 260C exhibited a thin, porous surface layer depleted in Ni and Cr, the alloy 718 coupons revealed essentially no wetting and, therefore, no interaction with that Hg at any temperature. Alloy 718 coupons suspended in the loops revealed inconsequentially small weight changes, and both the coupons and loop tubing exhibited no detectable metallographic evidence of attack.
Date: December 1, 1999
Creator: Pawel, S.J.; DiStefano, J.R. & Manneschmidt, E.T.
Partner: UNT Libraries Government Documents Department

Diamond-like carbon produced by plasma source ion implantation as a corrosion barrier

Description: There currently exists a broad range of applications for which the ability to produce an adherent, hard, wear and, corrosion-resistant coating plays a vital role. These applications include engine components, orthopedic devices, textile manufacturing components, hard disk media, optical coatings, and cutting and machining tools (e.g., punches, taps, scoring dies, and extrusion dies). Ion beam processing can play an important role in all of these technologies. Plasma source ion implantation (PSII) is an emerging technology which has the potential to overcome the limitations of conventional ion implantation by: (1) reducing the time and expense for implanting onto complex shapes and large areas and (2) extending the thickness of the modification zone through ion beam enhanced plasma growth of surface coatings. In PSII, targets are placed directly in a plasma source and then pulse biased to produce a non-line-of-sight process for complex-shaped targets without complex fixturing. If the pulse bias is a relatively high negative potential (20 to 100 kV) ion implantation will result. If however, a low voltage (50--1,200 eV) high duty cycle pulse bias is applied, film deposition from the chamber gas will result, thereby increasing the extent of the surface modification into the 1--10 micron regime. To evaluate the potential for DLC to be used as a corrosion barrier, Electrochemical Impedance Spectroscopy (EIS) and traditional electrochemistry techniques were used to investigate the breakdown mechanism in chloride and nonchloride containing environments. The effect of surface preparation on coating breakdown was also evaluated.
Date: March 1998
Creator: Lillard, R. S.; Butt, D. P.; Taylor, T. N.; Walter, K. C. & Nastasi, M.
Partner: UNT Libraries Government Documents Department

STIFLING OF CREVICE CORROSION IN ALLOY 22

Description: Artificially creviced Alloy 22 (N06022) specimens may be susceptible to crevice corrosion in presence of hot chloride containing solutions. The presence of oxyanions in the electrolyte, especially nitrate, may inhibit the nucleation and growth of crevice corrosion. Constant potential tests were performed using tightly creviced specimens of Alloy 22. It was found that crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. It was found that as the crevice corrosion nucleated, the current initially increased but later decreased. The net measured current can be converted into penetration following a power law fit of the experimental data. The average power law coefficient ''n'' was found to be 0.439, suggesting that even under constant applied potential, crevice corrosion penetration is diffusion controlled.
Date: July 1, 2005
Creator: Mon, K.G.; Gordon, G.M. & Rebak, R.B.
Partner: UNT Libraries Government Documents Department

Corrosion and stress-corrosion cracking of welded uranium-6 weight percent niobium

Description: The resistance of corrosion and stress-corrosion cracking of welded U--6 wt% Nb in oxygen-saturated water containing 50 ppM chloride ions was investigated. The tests showed that a post-weld heat treatment consisting of solution quenching and underaging (350 deg C for 42 min) provided the best resistance to corrosion and pitting corrosion. Although selective corrosion and pitting corrosion were observed on many of the specimens tested, no evidence of stress-corrosion cracking was found. (auth)
Date: December 27, 1973
Creator: Macki, J. M. & Kochen, R. L.
Partner: UNT Libraries Government Documents Department