Science.gov

Sample records for continuous cathodic protection

  1. Photovoltaic Power Without Batteries for Continuous Cathodic Protection

    NASA Technical Reports Server (NTRS)

    Muehl, W. W., Sr.

    1993-01-01

    The objective of this project was to successfully demonstrate that renewable energy can efficiently and economically replace dedicated non-renewable power sources. The COASTSYSTA designed, installed, and started up on 20 Jan. 1990, a state-of-the-art photovoltaic powered impressed current cathodic protection system (PVCPSYS) for steel and iron submerged structures. This system does not require any auxiliary/battery backup power. The PVCPSYS installed on 775 ft. of steel sheet piling of a Navy bulkhead is continuing to provide complete, continuous corrosion protection. This installation is well documented by COASTSYSTA and was verified on-site by the U.S. Army Corps of Engineers. The PVCPSYS uses only renewable energy and is environmentally clean. A patent is pending on the new technology. Other possible PVCPSYS applications are mothballed ships, docks, dams, locks, bridges, marinas, and pipelines. The Department of Defense Photovoltaic Review Committee and Sandia National Laboratories consider this successful and cost effective system a major advance in the application of photovoltaics.

  2. Photovoltaic power without batteries for continuous cathodic protection

    NASA Astrophysics Data System (ADS)

    Muehl, W. W., Sr.

    1994-02-01

    The COASTSYSTA designed, installed, and started up on 20 Jan. 1990, a state-of-the-art stand alone photovoltaic powered impressed current cathodic protection system (PVCPSYS) not requiring any auxiliary/battery backup power for steel and iron submerged structures. The PVCPSYS installed on 775' of steel sheet piling of a Navy bulkhead is continuing to provide complete, continuous corrosion protection. This has been well documented by COASTSYSTA and verified on-site by the U.S. Army Civil Engineering Research Laboratory, Champaign, Illinois and the Navy Energy Program Office-Photovoltaic Programs, China Lake, California. The Department of Defense (DoD) Photovoltaic Review Committee and Sandia National Laboratories consider this successful and cost effective system a major advance in the application of photovoltaic power. The PVCPSYS uses only renewable energy and is environmentally clean. A patent is pending on the new technology. Other possible PVCPSYS applications are mothballed ships, docks, dams, locks, bridges, marinas, offshore structures, and pipelines. The initial cost savings by installing a PVCPSYS vs. a conventional CP system was in excess of $46,000.00.

  3. Photovoltaic power without batteries for continuous cathodic protection

    NASA Astrophysics Data System (ADS)

    Muehl, W. W., Sr.

    1993-02-01

    The objective of this project was to successfully demonstrate that renewable energy can efficiently and economically replace dedicated non-renewable power sources. The COASTSYSTA designed, installed, and started up on 20 Jan. 1990, a state-of-the-art photovoltaic powered impressed current cathodic protection system (PVCPSYS) for steel and iron submerged structures. This system does not require any auxiliary/battery backup power. The PVCPSYS installed on 775 ft. of steel sheet piling of a Navy bulkhead is continuing to provide complete, continuous corrosion protection. This installation is well documented by COASTSYSTA and was verified on-site by the U.S. Army Corps of Engineers. The PVCPSYS uses only renewable energy and is environmentally clean. A patent is pending on the new technology. Other possible PVCPSYS applications are mothballed ships, docks, dams, locks, bridges, marinas, and pipelines. The Department of Defense Photovoltaic Review Committee and Sandia National Laboratories consider this successful and cost effective system a major advance in the application of photovoltaics.

  4. Photovoltaic power without batteries for continuous cathodic protection

    NASA Technical Reports Server (NTRS)

    Muehl, W. W., Sr.

    1994-01-01

    The COASTSYSTA designed, installed, and started up on 20 Jan. 1990, a state-of-the-art stand alone photovoltaic powered impressed current cathodic protection system (PVCPSYS) not requiring any auxiliary/battery backup power for steel and iron submerged structures. The PVCPSYS installed on 775' of steel sheet piling of a Navy bulkhead is continuing to provide complete, continuous corrosion protection. This has been well documented by COASTSYSTA and verified on-site by the U.S. Army Civil Engineering Research Laboratory, Champaign, Illinois and the Navy Energy Program Office-Photovoltaic Programs, China Lake, California. The Department of Defense (DoD) Photovoltaic Review Committee and Sandia National Laboratories consider this successful and cost effective system a major advance in the application of photovoltaic power. The PVCPSYS uses only renewable energy and is environmentally clean. A patent is pending on the new technology. Other possible PVCPSYS applications are mothballed ships, docks, dams, locks, bridges, marinas, offshore structures, and pipelines. The initial cost savings by installing a PVCPSYS vs. a conventional CP system was in excess of $46,000.00.

  5. Cathodic protection

    SciTech Connect

    Pfalser, I.L.; Brannan, M.S.

    1991-08-20

    This patent describes a cathodic protection system for protecting a metallic structure in contact with the earth from corrosion. It comprises at least one electrically conductive member positioned in a borehole in the earth which is defined by an earthen sidewall: a quantity of a particulate mixture of a clay and a carbonaceous solid which at least partially fills the borehole around the at least one conductive member such that the mixture contacts the earthen sidewall and the at least one conductive member, wherein the mixture has a clay to carbonaceous solid weight ratio of at least about 0.1:1; means for applying a DC electrical voltage to the metallic structure and the at least one conductive member such that the metallic structure is at a negative polarity and the at least one conductive member is at a positive polarity, whereby a current is established between the metallic structure and the at least one conductive member through the earth and the mixture.

  6. Cathodic protection of underground storage tanks using continuous polymeric cable anode systems

    SciTech Connect

    Werner, D.P.; Mussall, E.J.

    1995-12-31

    The US Environmental Protection Agency (EPA) has mandated several compliance deadlines for owners of underground storage tanks. These regulations include installation of vapor recovery systems, inventory control systems, tank tightness testing, overfill and overspill protection, and installation of cathodic protection systems, et al. This paper will focus on the installation of cathodic protection systems, the installation of which the EPA has mandated be complete prior to the end of 1998 for underground storage tanks.

  7. Cathodic protection -- Rectifier 46

    SciTech Connect

    Lane, W.M.

    1995-06-14

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms on the Hanford Reservation. The tank farms store radioactive waste.

  8. Cathodic protection -- Rectifier 47

    SciTech Connect

    Lane, W.M.

    1995-06-14

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms at the Hanford Reservation. The tank farms store radioactive waste.

  9. Cathodic protection system inspection 5

    NASA Astrophysics Data System (ADS)

    Jenkins, Jim; Polly, Dan

    1994-02-01

    The rectifier is the heart of an impressed current cathodic protection system. As it is subject to many adverse conditions including power surges, lightning strikes, vandalism, physical damage, and deterioration from atmospheric exposure, frequent inspections of rectifiers are vital to keeping an impressed current system operating so that it can provide nearly continuous protection of the underground, or submerged structures that are being protected.

  10. Cathodic protection maintenance for aboveground storage tanks

    SciTech Connect

    Koszewski, L.

    1995-12-31

    Cathodic protection systems are utilized to mitigate corrosion on the external bottom surfaces of aboveground storage tanks (ASTs). Cathodic protection systems should be part of a preventative maintenance program to minimize in-service failures. A good maintenance program will permit determination of continuous adequate cathodic protection of ASTs, through sustained operation and also provide the opportunity to detect cathodic protection system malfunctions, through periodic observations and testing.

  11. Photovoltaic power without batteries for continuous cathodic protection and an alternate photovoltaic/ultracapacitor combined power source

    SciTech Connect

    Muehl, W.W.

    1994-12-31

    The Coastal Systems Station (COASTSYSTA) designed, installed, and started up on 20 January 1990, a state-of-the-art stand-alone photovoltaic powered impressed current cathodic protection system (PVCPSYS) not requiring any backup power for steel and iron submerged structures. The PVCPSYS, installed on a 775-foot steel sheet piling of a Navy dock bulkhead, provides complete, continuous corrosion protection. The PVCPSYS has been in operation for more than five years, has not required any repair or maintenance, ad is environmentally clean. Initial cost savings of the PVCPSYS versus conventional cathodic protection system was $46,000. A second PVCPSYS was installed on another 800-foot bulkhead on 21 May 1993. It is also providing complete corrosion protection without backup power. Performance is well documented. Other potential applications are moth-balled ships, locks, dams, bridges, pipelines, and similar structures. These systems are considered a major advance by Sandia and the Department of Defense (DOD) Photovoltaic Review Committee. An ultra-capacitor, a recent hi-tech development that is environmentally clean, will be incorporated in the PVCPSYS when required to enhance the system`s capability. A photovoltaic/ultracapacitor (or equivalent) combined power source operating under adverse conditions, and/or to satisfy or meet regulations will assure cathodic protection, including pipelines carrying combustibles or other products that could otherwise create environmental problems.

  12. Photovoltaic power without batteries for continuous cathodic protection and an alternate photovoltaic/ultracapacitor combined power source

    SciTech Connect

    Muehl, W.W. Sr.

    1995-12-31

    The Coastal Systems Station (COASTSYSTA) designed, installed, and started up on 20 January 1990, a state-of-the-art stand-alone photovoltaic powered impressed current cathodic protection system (PVCPSYS) not requiring any backup power for steel and iron submerged structures. The PVCPSYS, installed on a 775-foot steel sheet piling of a Navy dock bulkhead, provides complete, continuous corrosion protection. The PVCPSYS has been in operation for more than five years, has not required any repair or maintenance, and is environmentally clean. Initial cost savings of the PVCPSYS versus conventional cathodic protection system was $46,000. A second PVCPSYS was installed on another 800-foot bulkhead on 21 May 1993. It is also providing complete corrosion protection without backup power. Performance is well documented. Other potential applications are moth-balled ships, locks, dams, bridges, pipelines, and similar structures. These systems are considered a major advance by Sandia and the Department of Defense (DOD) Photovoltaic Review Committee. An ultracapacitor, a recent hi-tech development that is environmentally clean, will be incorporated in the PVCPSYS when required to enhance the system`s capability. A photovoltaic/ultracapacitor (or equivalent) combined power source operating under adverse conditions, and/or to satisfy or meet regulations will assure cathodic protection, including pipelines carrying combustibles or other products that could otherwise create environmental problems. Patents are pending on this PVCPSYS and the photovoltaic/ ultracapacitor powered systems.

  13. 49 CFR 192.463 - External corrosion control: Cathodic protection.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false External corrosion control: Cathodic protection. 192.463 Section 192.463 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.463 External corrosion control: Cathodic protection. (a) Each cathodic...

  14. 49 CFR 192.463 - External corrosion control: Cathodic protection.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false External corrosion control: Cathodic protection. 192.463 Section 192.463 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.463 External corrosion control: Cathodic protection. (a) Each cathodic...

  15. 49 CFR 192.463 - External corrosion control: Cathodic protection.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false External corrosion control: Cathodic protection. 192.463 Section 192.463 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.463 External corrosion control: Cathodic protection. (a) Each cathodic...

  16. Offshore platform cathodic protection retrofits

    SciTech Connect

    Turnipseed, S.P.

    1996-10-01

    Cathodic protection (CP) is the primary technique used for underwater corrosion control on the majority of offshore steel structures. Offshore platforms are often kept in service far beyond their original design life. Refurbishment of the CP system is required when adequate protection can no longer be maintained. Various offshore platform CP retrofit designs are discussed.

  17. Cathodic protection diagnostic expert system

    SciTech Connect

    Van Blaricum, V.L.; Kumar, A. ); Park, Y.T. . Dept. of Computer Science)

    1994-12-01

    A knowledge-based diagnostic system has been developed for troubleshooting cathodic protection systems. The expert system is designed to work in conjunction with a database that stores inventory and field measurement information and flags problem areas. The system is described, and examples of troubleshooting using the system are presented.

  18. Cathodic protection installation for underground storage tanks

    SciTech Connect

    Koszewski, L.

    1995-12-31

    The 1998 deadline is fast approaching for upgrading Underground Storage Tanks (USTs) with cathodic protection. With so many tanks requiring upgrades over the next few years, tank owners and operators will likely find a shrinking pool of quality cathodic protection installation contractors to perform the necessary upgrading. The proper installation of cathodic protection components is critical to long term effective operation of the cathodic protection system.

  19. 49 CFR 192.463 - External corrosion control: Cathodic protection.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false External corrosion control: Cathodic protection. 192.463 Section 192.463 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.463 External corrosion control: Cathodic protection. (a) Each...

  20. 49 CFR 192.463 - External corrosion control: Cathodic protection.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false External corrosion control: Cathodic protection. 192.463 Section 192.463 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.463 External corrosion control: Cathodic protection. (a) Each...

  1. Cathodic protection design for aboveground storage tanks

    SciTech Connect

    Koszewski, L.; Quincy, G.L.

    1995-12-31

    The application of cathodic protection for aboveground storage tank (AST) bottoms has been accomplished in a variety of approaches, with varying degrees of success. Recent State regulations, requiring corrosion protection for new tanks and secondary containment for double bottom tanks, have prompted new application techniques to be developed for AST cathodic protection. Improved design applications are now available to todays` tank owners and operators to provide effective long term cathodic protection.

  2. Cathodic protection diagnostic expert system

    SciTech Connect

    Van Blaricum, V.L.; Kumar, A.; Park, Y.T.

    1994-12-31

    A knowledge-based diagnostic system called CP Diagnostic has been developed for troubleshooting sacrificial and impressed current cathodic protection systems. The expert system is designed to work in conjunction with the CP Diagnostic database system, which stores inventory and field measurement information for CP systems and flags problem areas. When a malfunction is detected, the expert system queries the user and the companion inventory and field measurement databases to determine its symptoms. The system will be described and examples of troubleshooting using the system will be presented.

  3. Sun powers Libya cathodic-protection system

    SciTech Connect

    Currer, G.W.

    1982-03-22

    Well castings and part of the main 300-mile-long, 32-in diameter pipeline from Sarir to Tobruk are cathodically protected by solar power, which prevents galvanic action by applying an electric direct current of appropriate magnitude and polarity to the steel structures. They then act as cathodes and become the recipients of metallic ions. At each cathodic-protection station, the solar-generaor system consists of solar-panel arrays, electronic controls, and batteries.

  4. Aboveground storage tank double bottom cathodic protection

    SciTech Connect

    Surkein, M.B.

    1995-12-31

    Cathodic protection is typically used to achieve corrosion control between bottoms of aboveground storage tanks with double bottoms. To determine the proper design of such systems, an investigation was conducted on the performance of two different cathodic protection system designs utilizing zinc ribbon anodes. A full scale field test on a 35 meter (115 feet) diameter tank was conducted to determine cathodic protection system performance. The test included periodic measurement of tank bottom steel potentials including on, instant off and polarization decay, anode current output and tank product level measurements.Results showed that zinc ribbon anode spacing in a chord fashion of 1.2 meter (4 feet) or less can be effective to achieve cathodic protection according to industry accepted standards. Utilizing the design information gained by the study, a standard sacrificial anode and impressed current anode cathodic protection system has been developed.

  5. Cathodic protection on concrete offshore platforms

    SciTech Connect

    Heuze, B.

    1980-05-01

    Experience with five cathodically protected North Sea concrete platforms has demonstrated the value of interconnecting the concrete-reinforcement steel with cathodically protected metal items on the structure (rather than insulating the steel from them) as a means of bringing the entire structure under the protection of the corrosion-control system. Lessons learned from this experience point out the importance of the duct material in safeguarding the prestressing tendons, the limitations of cathodic protection in cases of coating cracking and disbondment, and the precautions to be taken against stray welding currents. An improved approach to corrosion prevention focuses on the design philosophy, the current required by the reinforcing bar and well casing, the corrosion protection inside piping shafts and risers, and the required monitoring systems.

  6. UST -- Cathodic protection testing (maintenance and monitoring)

    SciTech Connect

    Maloney, T.A.

    1995-12-31

    Without proper maintenance, every tank system will eventually deteriorate. However, technology exists to extend structural life indefinitely if applied and maintained correctly. The keys to effective corrosion control of USTs are quality design and installation of equipment, use of proper technologies, and ongoing maintenance and monitoring. When a UST owner evaluates risk, corrosion control must be an integral part of their evaluation. The federal government recognizes the importance of ongoing corrosion control for underground storage tanks. Federal regulations (40 CFR Part 280) require each tank to be properly designed and constructed, and any portion underground that routinely contains product must be protected from corrosion, and to monitor the corrosion control to ensure continued protection. The regulations also require that the design, installation, and testing of cathodic protection systems be carried out by a person qualified by experience and training in corrosion control methods. Civil and criminal penalties can be imposed for noncompliance with the regulations. This paper provides background on maintenance of installed corrosion protection systems, testing requirements, and monitoring options available to owners of underground storage tanks.

  7. Cathodic protection retrofit of an offshore pipeline

    SciTech Connect

    Winters, R.H.; Holk, A.C.

    1997-09-01

    The cathodic protection anodes and corrosion coating on two 8-inch (203.2 mm) outside diameter (O.D.) offshore pipelines were damaged during deep water ({minus}380 feet, {minus}116 m) installation. In-situ methods for deep water inspection and repair of the pipelines` cathodic protection and coating systems were developed and performed. Methods are described in which underwater anode retrofits were performed and friction welding technology was used to re-attach anode leads. Standard procedures for underwater pipeline coating repair and remediation of damaged line pipe are provided.

  8. Acceptance Test Procedure for Cathodic Protection, Rectifier 11

    SciTech Connect

    Clifton, F.T.

    1995-04-28

    This Acceptance Test Procedure for Project W-030 Cathodic Protection Installation, 241-AY and 241-AZ Tank Farm Ventilation Upgrade, has been prepared to demonstrate that the cathodic protection system functions as required by project criteria.

  9. Cathodic protection requirements for deepwater systems

    SciTech Connect

    Menendez, C.M.; Hanson, H.R.; Kane, R.D.; Farquhar, G.B.

    1999-07-01

    Field and laboratory experience related to requirements for cathodic protection (CP) in deep water are reviewed with emphasis on identification of the major variables that need to be specified for successful deepwater CP designs for offshore structures. The subject is addressed based on the historical development of cathodic protection design methodologies for offshore structures focusing on sacrificial anode systems and trends that have resulted in specific changes in design requirements. Three main subjects are discussed: (1) application of existing industry standards such as NACE RP0176; (2) environmental factors--dissolved oxygen, temperature, salinity, pH, water velocity and fouling; and (3) calcareous deposits--difference between shallow and deep waters. Current practice of design criteria and systems for deepwater applications is assessed, including initial polarization, use of coatings and anode materials. The results from laboratory tests are compared with available documented service experiences and field tests results.

  10. Auger tension leg platform cathodic protection system

    SciTech Connect

    Goolsby, A.D.; Smith, J.D.

    1995-11-01

    In 1986, Shell began investigating corrosion control systems for a generic 3,000 ft. water depth Tension Leg Platform (TLP) type structure to be located in the north-central Gulf of Mexico. In 1987, the 2,850 ft. deep Garden Banks block 426 ``Auger`` location was chosen for the first TLP, and the detailed design process began in earnest. During late 1993 and early 1994, the Auger hull was mated with the other components at its permanent site, and first oil and gas production began April 15, 1994. This paper describes the corrosion control design for the exterior submerged and buried steel surfaces of the 2,850 ft. (869 m) water depth Auger Tension Leg Platform structure. Each major type of component (hull, subsea marine wellhead/guidebase, tendon foundation template, tendon, and production riser) has its own combination of coating system and cathodic protection system designed for a thirty five year lifetime. Cathodic protection (CP) is achieved using a variety of sacrificial anode alloys and geometries (e.g. bracelet, flush-mount, and standoff anodes). Anode and cathode CP design parameters for each component depend upon water depth, and were developed using field test data, laboratory studies, field measurements on existing structures, and available literature information. CP design was performed using design spreadsheets constructed for each component, which optimized anode geometries. Extensive quality assurance efforts were part of the anode procurement process, to ensure performance for the intended life of the corrosion-control systems. Results of early in-service CP surveys of the tendons and guidebases are presented, showing the successful achievement of cathodic protection against seawater corrosion. Corrosion control of one additional system, the eight point lateral mooring system, is not addressed here.

  11. Modeling of underground cathodic protection stray currents

    SciTech Connect

    Brichau, F.; Deconinck, J.; Driesens, T.

    1996-06-01

    OKAPPI, a numerical model for calculating cathodic protection (CP) problems involving underground pipelines, was extended to situations involving stray currents. Aboveground structures such as rail bars, power stations, electric train or tram vehicles, and overhead lifelines were integrated in the existing model in a straightforward and transparent way. As a result, it was shown that the model can be used to deal with most of the CP problems encountered with underground pipes. Situations where the sources of stray current, such as other CP installations or earthing systems located in the soil, were modeled and compared with theory. Cases involving the four standard kinds of CP interference (anodic, cathodic, combined, and induced) were calculated and discussed. A few complex situations involving overhead systems such as trams or railways were investigated. The theoretically expected phenomena were confirmed by the calculations.

  12. Underground storage tank cathodic protection design

    SciTech Connect

    Garrity, K.C.

    1995-12-31

    The US Environmental Protection Agency has enacted rules regulating the use, installation and operation of underground storage tanks. Effective December 22, 1988, the rule applies to underground storage tanks and piping containing regulated substances. These rules supersede the Interim Prohibition issued in May, 1985. Owners must comply with the rules by December, 1998. These regulations mandate that the installation prevent releases (leaks) due to corrosion or structural failure for the operational life of the tank. Further, the tank and piping must be cathodically protected against corrosion, constructed of noncorrosive material, steel clad with a noncorrosive material or designed in a manner to prevent the release or threatened release of any stored substance. The regulations also mandate that material used in construction or lining of the tank be compatible with the substance to be stored. This paper discusses the basic corrosion mechanisms which affect direct buried steel tankage and piping systems as well as basic principles for applying cathodic protection as a means of corrosion control intended to satisfy EPA Regulations.

  13. Cathodic protection of a remote river pipeline

    SciTech Connect

    Martin, B.A. )

    1994-03-01

    The 261-km long 500-mm diam Kutubu pipeline, which runs through dense jungle swamps in Papua, New Guinea, was built for Chevron Niugini to transport oil from the remote Kutubu oil production facility in the Southern Highlands to an offshore loading facility. The pipeline was laid with a section in the bed of a wide, fast-flowing river. This section was subject to substantial telluric effects and current density variations from changing water resistivities. The cathodic protection system's effectiveness was monitored by coupon off'' potentials and required an innovative approach.

  14. Cathodic protection -- Addition of 6 anodes to existing rectifier 31

    SciTech Connect

    Lane, W.M.

    1995-06-14

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system additions are installed, connected, and function as required by project criteria. The cathodic protection system is for the tank farms on the Hanford Reservation. The tank farms store radioactive wastes.

  15. Cathodic protection design using the regression and correlation method

    SciTech Connect

    Niembro, A.M.; Ortiz, E.L.G.

    1997-09-01

    A computerized statistical method which calculates the current demand requirement based on potential measurements for cathodic protection systems is introduced. The method uses the regression and correlation analysis of statistical measurements of current and potentials of the piping network. This approach involves four steps: field potential measurements, statistical determination of the current required to achieve full protection, installation of more cathodic protection capacity with distributed anodes around the plant and examination of the protection potentials. The procedure is described and recommendations for the improvement of the existing and new cathodic protection systems are given.

  16. Effects of cathodic disbonding and blistering on current demand for cathodic protection of coated steel

    SciTech Connect

    Knudsen, O.O.; Steinsmo, U.

    2000-03-01

    Cathodic disbonding, blistering, and current demand for cathodic protection were measured for nine commercial coatings for submerged steel structures. The ASTM-G8 standard test and a long-term test (2 years), simulating North Sea conditions, were used. The relevance of the ASTM-G8 test as a prequalification test was evaluated by comparing cathodic disbonding in the two tests. After 800 days in the long-term test, the correlation to ASTM-G8 was good. The correlation coefficient was 0.98. The current demand for cathodic protection increased when the coatings blistered. Examination of the blisters showed that they had cracked. After 2 years of testing, the current demand only had increased for the thin coatings (< 150 {micro}m). The current demand for the thicker coatings (> 450 {micro}m) had not increased, in spite of significant cathodic disbonding for some coatings. Coating breakdown factors, defined as the ratio between current demand for cathodic protection for the coated samples and samples of bare steel, were calculated. These factors were compared with the design values for cathodic protection in Det Norske Veritas (DNV) RP B401 and NORSOK M-CR-503. For all coatings, the coating breakdown rate was lower than the design values.

  17. Cathodic Protection of the Yaquina Bay Bridge

    SciTech Connect

    Bullard, Sophie J.; Cramer, Stephen D.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Russell, James H.; Laylor, H.M.; Cryer, C.B.

    2001-02-01

    The Yaquina Bay Bridge in Newport, Oregon, was designed by Conde B. McCullough and built in 1936. The 3,223-foot (982 m) structure is a combination of concrete arch approach spans and a steel through arch over the shipping channel. Cathodic protection is used to prevent corrosion damage to the concrete arches. The Oregon Department of Transportation (Oregon DOT) installed a carbon anode coating (DAC-85) on two of the north approach spans in 1985. This anode was operated at a current density of 6.6 mA/m2(0.6 mA/ft2). No failure of the conductive anode was observed in 1990, five years after application, or in 2000, 15 years after application. Thermal-sprayed zinc anodes 20 mils (0.5 mm) thick were applied to half the south approach spans beginning in 1990. Thermal-sprayed zinc anodes 15 mils (0.4 mm) thick were applied to the remaining spans in 1996. These anodes were operated at a current density of 2.2 mA/m2(0.2 mA/ft2). In 1999, four zones on the approach spans were included in a two-year field trial of humectants to improve zinc anode performance. The humectants LiNO3 and LiBr were applied to two zones; the two adjacent zones were left untreated as controls. The humectants substantially reduced circuit resistance compared to the controls.

  18. Intermittent cathodic protection for steel reinforced concrete bridges

    SciTech Connect

    Bullard, Sophie J.; Ziomek-Moroz, Margaret; Cramer, Stephen D.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Russell, James H.; Soltesz, S.M.

    2002-01-01

    Thermal-sprayed zinc anodes are used for impressed current cathodic protection (ICCP) systems on Oregon's reinforced concrete coastal bridges to prevent chloride-induced corrosion damage. Thermal-sprayed zinc performs well as an ICCP anode but the service life of the zinc anode is directly related to the average current density used to operate the systems. After a ICCP system is turned off, the rebar in the concrete remains passive and protected for a period of time. Intermittent operation of CP systems is possible when continuous corrosion rate monitoring is used to identify conditions when the CP system needs to be turned on to reestablish protection conditions for the rebar. This approach applies CP protection only when needed and reflects the fact that external protection may not be needed for a range of environmental conditions. In doing so, intermittent CP would lower the average current necessary to protect rebar, increase the anode service life, and reduce the lifetime costs for protecting reinforced concrete bridges.

  19. Exploring the complexity of the mechanism of cathodic protection

    SciTech Connect

    Thompson, N.G.; Lawson, K.M.; Beavers, J.A.

    1994-12-31

    The present understanding of the mechanism of cathodic protection is too simplistic to explain when, why, and under what conditions corrosion is mitigated for a buried pipeline. This paper presents a general framework which attempts to explain why cathodic protection is achieved and what factors are critical in determining the ability of cathodic protection to mitigate corrosion. It is speculated that the changes in the ``near-surface`` environment due to the reduction processes on the cathodically protected steel surface play a significant role in mitigating corrosion and in defining the level of polarization achieved. This is accomplished by contributing a concentration polarization term to the overall level of polarization. Furthermore, the concentration polarization term explains many field related observations not easily explained by activation polarization and mixed potential theory. 32 refs.

  20. Solar energy for cathodic protection, monitoring and communication

    SciTech Connect

    Lasa, I.R.; Powers, R.G.; Kessler, R.J.

    1994-12-31

    This paper discusses the results of a short term evaluation of two nearly identical solar energy cathodic protection (CP) systems. The first system was observed under controlled laboratory conditions while the second was incorporated on an existing CP system on a bridge substructure in Jacksonville, Florida. Each system was provided with data acquisition equipment for monitoring. The field site was provided with a cellular transceiver for remote monitoring. Economic considerations are also discussed and compared to rectifier powered cathodic protection.

  1. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Criteria for Cathodic Protection and Determination of Measurements D Appendix D to Part 192 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION...

  2. EVALUATION OF IMPRESSED ELECTROMOTIVE FORCE CATHODIC PROTECTION

    DTIC Science & Technology

    Electromotive couples consisting of 0.064 in. x 24 in. x 24 in. bare 7075-T6 aluminum cathodes and 0.064 in. x 2 in. x 3 in. RC-70 titanium or...such a manner that it opposed the galvanic current. In a series of tests wherein the impressed voltage and current was varied from specimen to specimen

  3. Installation of aboveground storage tank cathodic protection systems

    SciTech Connect

    Garrity, K.C.

    1995-12-31

    The application of cathodic protection is an effective means of controlling corrosion on tank bottom undersides. The success of the cathodic protection system is dependent upon proper design and system selection and effective monitoring of the level of protection being afforded to the entire tank bottom underside. The use of angle drilled anodes around the periphery of the storage tank should provide a better distribution of current to the tank center on existing tanks. The use of undertank ribbon anode system and secondary containment should prove effective for newly constructed tanks.

  4. Cathodic protection on the Dampier to Perth pipeline - Australia

    SciTech Connect

    McCoy, J.

    1989-02-01

    The Dampier-Perth Pipeline in Australia transports natural gas from the north to the south over a distance of 1540 km. The ground along the route is high in electrical resistivity. Coupled with the fluid bed epoxy (FBE) coating, this high electrical resistivity posed some special design problems for cathodic protection indirectly influencing spacing of cathodic protection stations, provision of groundbeds, compatibility of earthing, and groundbed interference. A major consideration at the design stage was IR voltage drop in the soil, which necessitated extensive manipulation of earthing placement and materials. Telluric currents were also of concern. This article provides insight into design considerations and also reviews the performance of the permanent cathodic protection system.

  5. Hydrogen embrittlement of cathodically protected subsea bolting alloys

    SciTech Connect

    Wolfe, L.H.; Burnette, C.C.; Joosten, M.W. )

    1993-07-01

    Normal operations of cathodic protection (CP) systems caused hydrogen embrittlement failures of subsea bolts made of Monel K-500 alloy (UNS N05500) on offshore platforms. Subsequent testing showed that the embrittlement could be predicted from cathodically protected slow strain rate tensile tests. Additional slow strain rate tests have shown that CP caused embrittlement of Ferralium 255 (S32550), Inconel X-750 (N07750), Inconel 718 (N07718), high strength steel, and 13% chromium alloys. Beryllium copper (C17200), A-286 steel (S66286), Beta-C titanium (R58640), and steel at a yield strength of 793 MPa (115 ksi) were not embrittled under the same conditions.

  6. Technology assists in testing, improving storage tank cathodic protection

    SciTech Connect

    1996-10-21

    Horizontal boring allowed Amoco Pipeline Co. easily and inexpensively to retrofit cathodic protection under storage tanks at its Wyco, Colo., terminal. With the Bore Logic system, developed by Coroocon Inc., Broomfield, Colo., operators insert slotted PVC piping at very shallow depths, 18--24 inches under existing tank bottoms. The pipe networks are then used for developing accurate tank-to-soil potential profiles, placing reference cells beneath tank centers and, when necessary, retrofitting tanks with undertank cathodic protection systems. The paper describes the system and its installation.

  7. Viability of stored seed: extension by cathodic protection.

    PubMed

    Pammenter, N W; Adamson, J H; Berjak, P

    1974-12-20

    Placing seeds on a negatively charged conductor extended their viability during artificial aging. Such cathodic protection may reduce free radical attack by providing a source of electrons. The results stupport the hypothesis of free radical damage to cellular components and are consistent with such damage being important in deteriorative senescence changes.

  8. 49 CFR 195.563 - Which pipelines must have cathodic protection?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Which pipelines must have cathodic protection? 195... have cathodic protection? (a) Each buried or submerged pipeline that is constructed, relocated, replaced, or otherwise changed after the applicable date in § 195.401(c) must have cathodic protection....

  9. 49 CFR 195.563 - Which pipelines must have cathodic protection?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Which pipelines must have cathodic protection? 195... have cathodic protection? (a) Each buried or submerged pipeline that is constructed, relocated, replaced, or otherwise changed after the applicable date in § 195.401(c) must have cathodic protection....

  10. 49 CFR 195.563 - Which pipelines must have cathodic protection?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Which pipelines must have cathodic protection? 195... have cathodic protection? (a) Each buried or submerged pipeline that is constructed, relocated, replaced, or otherwise changed after the applicable date in § 195.401(c) must have cathodic protection....

  11. 49 CFR 195.563 - Which pipelines must have cathodic protection?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Which pipelines must have cathodic protection? 195... have cathodic protection? (a) Each buried or submerged pipeline that is constructed, relocated, replaced, or otherwise changed after the applicable date in § 195.401(c) must have cathodic protection....

  12. 49 CFR 195.563 - Which pipelines must have cathodic protection?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Which pipelines must have cathodic protection? 195... have cathodic protection? (a) Each buried or submerged pipeline that is constructed, relocated, replaced, or otherwise changed after the applicable date in § 195.401(c) must have cathodic protection....

  13. Testing cathodic protection systems on aboveground storage tanks

    SciTech Connect

    Garrity, K.C.

    1995-12-31

    The evaluation of cathodic protection systems on aboveground storage tanks presents a unique challenge. Paramount with selection of system type is the method of verification that corrosion control has indeed been achieved. Past experience indicates that standard monitoring procedures intended to determine satisfaction of the industry recognized criteria may not be adequate in analyzing the degree of protection being afforded a storage tank resting on the ground. The standard method of determining the effectiveness of cathodic protection on any structure is the structure-to-electrolyte potential measurement. These measurements are performed utilizing a high impedance voltmeter and a stable, reproducible reference electrode contacting the electrolyte. The paper describes several case histories to illustrate methods.

  14. Internal cathodic protection of cement-lined steel pipes

    SciTech Connect

    Jensen, F.O. ); Tems, R.D. )

    1988-07-01

    Internally coated, cement-lined, carbon steel pipes have been used extensively for ballast- and service-water systems offshore. Mechanical cracking of the lining, undercutting, and erosion have resulted in corrosion and system leaks. Cathodic protection is one alternative that has been evaluated as a solution. Cathodic protection normally gives limited protection when applied internally to a pipeline system. Tests have been performed to evaluate this hypothesis and the possibility of improved current distribution due to the cement lining. This paper presents the test results as well as a solution to the problem. Internally coated, cement-lined steel pipes are used for ballast-water, service-water, and fire-water systems in the offshore oil and gas production industry.

  15. Photovoltaic-powered regulated cathodic-protection system

    NASA Astrophysics Data System (ADS)

    Anis, Wagdy R.; Alfons, Hany A.

    The objective of a cathodic protection system is to protect metallic structures against corrosion. To achieve this, a sacrificial anode is connected to the protected structure (which acts as a cathode) through a d.c. power supply. To stop the corrosion, the protected structure requires a constant current. The current is determined by the metal and area of the structure, as well as the surrounding medium. The major difficulty in achieving a constant current is the variation in the resistivity of the surrounding medium that is caused by changes in the climatic conditions. Conventional cathodic-protection systems resolve this problem by manual adjustment of the d.c. voltage periodically to obtain a constant current. Such adjustment depends on the experience of the technician and the accuracy of the measuring equipment. Moreover if the interval between successive adjustments is relative long, the corrosion could become excessive. To overcome such difficulties, an automatically regulated system has been developed. The proposed system senses variations is the resistivity of the surrounding medium and adjusts the d.c. voltage accordingly so that the current is kept constant at the required level. The design of a solar photovoltaic system to supply the required d.c. power is discussed in this communication.

  16. Application of BEM to cathodic protection of seawater pump

    SciTech Connect

    Miyasaka, M.; Ishiguro, J.; Kishimoto, K.; Aoki, S.

    1995-11-01

    A three-dimensional boundary element method (3D-BEM) was developed to quantitatively estimate cathodic protection and macro-cell corrosion. To confirm the validity and usefulness of the BEM for analysis of fluid machines handling seawater with complex 3D fields, experiments and analyses were performed. A cast iron vertical pump with Zn anodes for cathodic protection, was submerged in seawater and operated. Potential distributions inside the pump and anodic currents on the Zn anodes were measured. Polarization characteristics of the pump material were also examined as functions of flow rate, time and temperature. Extremely accurate analyses on potential and current density distributions were performed by reflecting the polarization characteristics in the boundary conditions, and by means of appropriate modeling that takes account of the symmetry of the object being analyzed.

  17. Cathodic protection of offshore structures - Problems and solutions

    SciTech Connect

    Robson, D.N.C.

    1985-01-01

    The paper outlines the three basic options for cathodically protecting offshore structures; namely impressed current or sacrificial anodes protecting a bare metal structure or sacrificial anodes on a totally painted structure. Some of the problems encountered by these systems are described and some specific examples experienced by Britiol structures are discussed in more detail. Various solutions for overcoming these problems are discussed and comparisons made of their respective costs and ease of implementation. Finally, some solution to CP problems adopted by Britoil are described with emphasis on the difficulties in implementation.

  18. 49 CFR 195.571 - What criteria must I use to determine the adequacy of cathodic protection?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false What criteria must I use to determine the adequacy of cathodic protection? 195.571 Section 195.571 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY...

  19. Cathodic Protection Deployment on Space Shuttle Solid Rocket Boosters

    NASA Technical Reports Server (NTRS)

    Zook, Lee M.

    1998-01-01

    Corrosion protection of the space shuttle solid rocket boosters incorporates the use of cathodic protection(anodes) in concert with several coatings systems. The SRB design has large carbon/carbon composites(motor nozzle) electrically connected to an aluminum alloy structure. Early in the STS program, the aluminum structures incurred tremendous corrosive attack due primarily to the galvanic couple to the carbon/carbon nozzle at coating damage locations. Also contributing to the galvanic corrosion problem were stainless steel and titanium alloy components housed within the aluminum structures and electrically connected to the aluminum structures. This paper will highlight the evolution in the protection of the aluminum structures, providing historical information and summary data from the operation of the corrosion protection systems. Also, data and information will be included regarding the evaluation and deployment of inorganic zinc rich primers as anode area on the aluminum structures.

  20. Cathodic protection deployment on space shuttle solid rocket boosters

    SciTech Connect

    Zook, L.M.

    1999-07-01

    Corrosion protection of the space shuttle solid rocket boosters incorporates the use of cathodic protection (anodes) in concert with several coatings systems. The SRB design has large carbon/carbon composite (motor nozzle) electrically connected to an aluminum alloy structure. Early in the STS program, the aluminum structures incurred tremendous corrosive attack at coating damage locations due primarily to galvanic coupling with the carbon/carbon nozzle. Also contributing to the galvanic corrosion problem were stainless steel and titanium alloy components housed within the aluminum structures and electrically connected to the aluminum structures. This paper highlights the evolution in the protection of the aluminum structures, providing historical information and summary data from the operation of the corrosion protection systems. Also, data and information are included regarding the evaluation and application of inorganic zinc rich primers to provide anode area on the aluminum structures.

  1. Cathodic protection criteria for prestressed concrete pipe -- an update

    SciTech Connect

    Hall, S.C.

    1998-12-31

    Prestressed concrete cylinder pipe (PCCP) is used in water and waste water systems that serve virtually every major city in North America. Under certain conditions, such as high chloride environments, the steel can depassivate, leading to corrosion. Under these conditions, cathodic protection (CP) can be used to protect the encased steel elements. This paper provides the theoretical consideration and the results of laboratory and field investigations performed during the past decade to determine the effects of CP on the performance of passivated, corroded, and split prestressing wire immersed in an environment to simulate sound mortar and mortar surrounding severely corroded wire. The current densities required to achieve a 100 mV polarization or depolarization shift and the maximum potential criterion to prevent hydrogen embrittlement were determined. The effect of low pH due to corroding wire, the susceptibility of prestressing wire to hydrogen embrittlement, and the approximate length of time and potentials to produce hydrogen embrittlement and eventual wire failure were determined. The effect of discontinuing high levels of CP on the diffusion of hydrogen from wire and the recovery of ductility was evaluated. The amount of current flowing to the prestressing wire and steel cylinder at various current densities were also determined. Case histories of five cathodically protected pipelines are given. The data and results are presented and the minimum and maximum potential levels are recommended. The use of potential monitoring of PCCP to locate corrosion and possible causes of corrosion requiring CP is also presented.

  2. Biocidal effect of cathodic protection on bacterial viability in biofilm attached to carbon steel.

    PubMed

    Miyanaga, Kazuhiko; Terashi, Ryosuke; Kawai, Hirofumi; Unno, Hajime; Tanji, Yasunori

    2007-07-01

    Biofilm formed on carbon steel by various species of bacterial cells causes serious problems such as corrosion of steel, choking of flow in the pipe, deterioration of the heat-transfer efficiency, and so on. Cathodic protection is known to be a reliable method for protecting carbon steel from corrosion. However, the initial attachment of bacteria to the surface and the effects of cathodic protection on bacterial viability in the biofilm have not been clarified. In this study, cathodic protection was applied to an artificial biofilm containing Pseudomonas aeruginosa (PAO1), a biofilm constituent, on carbon steel. The aims of this study were to evaluate the inhibition effect of cathodic protection on biofilm formation and to reveal the inhibition mechanisms. The viability of PAO1 in artificial biofilm of 5 mm thickness on cathodically protected steel decreased to 1% of the initial cell concentration. Analysis of pH distribution in the artificial biofilm by pH microelectrode revealed that pH in proximity to carbon steel increased to approximately 11 after cathodic protection for 5 h. Moreover, 99% of region in the artificial biofilm was under the pH conditions of over nine. A simulation of pH profile was shown to correspond to experimental values. These results indicate cells in the artificial biofilm were killed or damaged by cathodic protection due to pH increase.

  3. Influence of cathodic protection on the lifetime extension of painted steel structures

    NASA Astrophysics Data System (ADS)

    Yoo, Y. R.; Cho, H. H.; Take, S.; Kim, J. G.; Kim, Y. S.

    2006-06-01

    For corrosion to occur on a coated metal surface, an electrochemical double layer must be established. Hence, the adhesion between the substrate and the coating must be weakened to enable a separate thin layer of water to be formed at the interface from water that has permeated the coating. To prevent the failure of a painted coating, we applied a cathodic protection method. This method has been controversial for a few years because cathodic protection can induce cathodic delamination of the entire surface, especially near the anode, and also because it is not effective on a not-wetted surface from the anode. We therefore evaluated the efficiency of cathodic protection for 700 days in an atmospheric environment and performed surface observation, AC impedance measurements and corrosion tests. In the case of a noncathodic protected painted steel specimen, blisters formed after 100 days and grew in number for the remainder of the test. However, cathodic protection of the painted steel increased the coating resistance and extended the lifetime of the coating. According to our calculation with the BEASY program, the thickness of the water film under a rain condition barely influenced the protection potential. The high voltage of the cathodic protection and the subsequent cathodic delamination caused the paint to peel off near the anode. Hence, the protection voltage should be controlled in accordance with changes to the environmental condition.

  4. E.M.I Effects of Cathodic Protection on Electromagnetic Flowmeters

    PubMed Central

    Gundogdu, Serdar; Sahin, Ozge

    2007-01-01

    Electromagnetic flowmeters are used to measure the speed of water flow in water distribution systems. Corrosion problem in metal pipelines can be solved by cathodic protection methods. This paper presents a research on corruptive effects of the cathodic protection system on electromagnetic flowmeter depending on its measuring principle. Experimental measurements are realized on the water distribution pipelines of the Izmir Municipality, Department of Water and Drainage Administration (IZSU) in Turkey and measurement results are given. Experimental results proved that the values measured by the electromagnetic flowmeter (EMF) are affected by cathodic protection system current. Comments on the measurement results are made and precautions to be taken are proposed.

  5. Designing cathodic protection systems for marine structures and vehicles. ASTM special technical publication 1370

    SciTech Connect

    Hack, H.P.

    1999-07-01

    Cathodic protection is an important method of protecting structures and ships from the corrosive effects of seawater. Poor designs can be far more costly to implement than optimal designs, Improper design can cause overprotection, with resulting paint blistering and accelerated corrosion of some alloys, underprotection, with resultant structure corrosion, or stray current corrosion of nearby structures. The first ASTM symposium specifically aimed at cathodic protection in seawater was intended to compile all the criteria and philosophy for designing both sacrificial and impressed current cathodic protection systems for structures and vehicles in seawater. The papers which are included in this STP are significant in that they summarize the major seawater cathodic protection system design philosophies. Papers have been processed separately for inclusion on the database.

  6. DEMONSTRATION AND EVALUATION OF TECHNOLOGIES FOR DETERMINING THE SUITABILITY OF USTS FOR UPGRADING WITH CATHODIC PROTECTION

    EPA Science Inventory

    Field applications of three alternate technologies for assessing the suitability of underground storage tanks for upgrading by the addition of cathodic protection were observed and documented. The technologies were applied to five existing underground storage tanks that were slat...

  7. DEMONSTRATION AND EVALUATION OF TECHNOLOGIES FOR DETERMINING THE SUITABILITY OF USTS FOR UPGRADING WITH CATHODIC PROTECTION

    EPA Science Inventory

    Field applications of three alternate technologies for assessing the suitability of underground storage tanks for upgrading by the addition of cathodic protection were observed and documented. The technologies were applied to five existing underground storage tanks that were slat...

  8. Demonstration of Photovoltaic-Powered Cathodic Protection System with Remote Monitoring Capability

    DTIC Science & Technology

    2014-02-01

    ER D C/ CE RL T R- 14 -3 DoD Corrosion Prevention and Control Program Demonstration of Photovoltaic-Powered Cathodic Protection System... Prevention and Control Program ERDC/CERL TR-14-3 February 2014 Demonstration of Photovoltaic-Powered Cathodic Protection System with Remote...demonstration was performed for the Office of the Secretary of De- fense (OSD) under Department of Defense (DoD) Corrosion Control and Prevention Project

  9. Internal cathodic protection of piping system by the RCP method: What is the experience?

    SciTech Connect

    Johnsen, R.; Valen, S.; Gartland, P.O.; Drugli, J.M.

    1997-12-01

    Internal cathodic protection by resistor controlled anodes--Resistor controlled Cathodic Protection (RCP)--was introduced in 1991 as an alternative method for the prevention of localized corrosion of seawater transportation systems. More than five hundred RCP anodes have been installed in seawater piping systems made from highly alloyed stainless steel which had suffered from corrosion. This paper describes some of the installations including experiences so far. In addition the possible use of AISI 316L combined with RCP anodes is described.

  10. Cathodic protection system design for steel pilings of a wharf structure

    SciTech Connect

    Nikolakakos, S.

    1999-07-01

    Corrosion of steel pilings in sea and brackish water is mostly due to the establishment of localized corrosion cells and the effects of the tidal changes. The most frequently used corrosion protection systems are coatings and/or cathodic protection. These protective systems when properly designed, installed and operated are very effective in preventing corrosion problems. The design of a cathodic protection system, in order to be effective and reliable, must take into consideration all technical design criteria, the type of materials used, the geometric shape of the structure, environmental conditions, site restrictions, and any outside interferences. These design considerations, as well as the use of design data and an overall design methodology for a cathodic protection system for pipe and sheet piling used in a wharf structure, are discussed in this paper.

  11. Cathodic protection by zinc sacrificial anodes: impact on marine sediment metallic contamination.

    PubMed

    Rousseau, C; Baraud, F; Leleyter, L; Gil, O

    2009-08-15

    Cathodic protection by sacrificial zinc anodes is often applied to prevent immerged metallic structures from corrosion. But this technique induces the zinc anodes dissolution, which can induce marine sediments and seawater contamination. A large scale experiment, in natural seawater, was conducted during 12 months, in order to evaluate the potential environmental impact of this continuous zinc dissolution, and of some necessary cleaning operations of the anodes surfaces. The heavy metal (Cr, Cu, Pb and Zn) concentration in water and sediment samples was monitored. A sequential extraction procedure was applied on sediment samples to differentiate the zinc mobile fractions from the residual one. A significant increase of zinc concentration was observed in water as well as in the surface sediments under the specific operating conditions. Sediments then become a secondary pollution source, as the sorbed labile zinc can be remobilized to seawater.

  12. Embedded reference electrodes for corrosion potential monitoring, electrochemical characterization, and controlled-potential cathodic protection

    NASA Astrophysics Data System (ADS)

    Merten, Bobbi Jo Elizabeth

    aluminum could be designed through continued mixture optimization. The Ag wire ERE has been utilized for the characterization and ranking of experimental coatings on metal substrates. Structural health monitoring and corrosion potential feedback of cathodic protection systems are additional uses. There is some indication that CPCP may be applied by ERE to control the substrate polarization for an organic coating system.

  13. Continued Development and Testing of Tungsten Controlled Porosity Dispenser Cathodes.

    DTIC Science & Technology

    1985-02-01

    DYNAMICS DIV ,EB 85 UNCLSSIFIED EDD-I-69514 N18914-8i-C-2245 F/O 1/6 NL=uuaa=7Emmmhmhhhlo Eu.’.comom...1-0 II 28 2-5 liltimmn 2 4 161 *2 (4 I 6 LL It’ ELECTRON DYNAMICS DIVISION In FINAL REPORT CONTINUED DEVELOPMENT AND TESTING OF TUNGSTEN...AIRCRAFT COMPANY ELECTRON DYNAMICS DIVISION 3100 WEST LOMITA BOULEVARD P.O. BOX 2999 TORRANCE, CA 90509 -. . .~ .~ . . .~ . . .~- . -. 0 TABLE OF CONTENTS

  14. Monitoring cathodic protection systems: Observational causes of low readings

    SciTech Connect

    Haffer, R.G.

    1997-09-01

    Monitoring relatively new cathodic systems on steel Underground Storage Tanks (USTs) is a very straightforward business. In theory 100% of all systems tested should adhere to the NACE`s standard RP-02-85 (and consequently government compliance) without much difficulty. But an enigma exists in that a relatively small number of tanks are not able to meet that criteria. This paper intends to explore the human element often responsible for the factors which result in non-conforming potential readings.

  15. Cathodic protection of steel reinforced concrete facilitated by using carbon fiber reinforced mortar or concrete

    SciTech Connect

    Hou, J.; Chung, D.D.L.

    1997-05-01

    Due to the decrease in volume electrical resistivity associated with carbon fiber addition (0.35 vol.%) to concrete (embedding steel rebar), concrete containing carbon fibers and silica fume reduced by 18% the driving voltage required for cathodic protection compared to plain concrete, and by 28% compared to concrete with silica fume. Due to the decrease in resistivity associated with carbon fiber addition (1.1 vol.%) to mortar, overlay (embedding titanium wires for electrical contacts to steel reinforced concrete) in the form of mortar containing carbon fibers and latex reduced by the 10% the driving voltage required for cathodic protection, compared to plain mortar overlay. In spite of the low resistivity of mortar overlay with carbon fibers, cathodic protection required multiple metal electrical contacts embedded in the mortar at a spacing of 11 cm or less.

  16. Protected Sulfur Cathode with Mixed Conductive Coating Layer for Lithium Sulfur Battery

    NASA Astrophysics Data System (ADS)

    Jin, Jun; Wen, Zhaoyin; Wang, Qingsong; Gu, Sui; Huang, Xiao; Chen, Chunhua

    2016-10-01

    A mixed conductive coating layer composed of lithium ion conductive ceramic powder, carbon and binder was introduced on the surface of a sulfur electrode. This coating layer is designed to suppress the migration of lithium polysulfides from the sulfur electrode, and improve the cycling capacity of a lithium sulfur battery. The protected sulfur cathode with a mixed conductive coating layer delivered an initial specific capacity of 1236 mAh g-1 at 0.5C and maintained a capacity of 842 mAh g-1 after 100 cycles. In particular, a soft package battery with protected cathode exhibits improved cycling capacity and excellent rate performance.

  17. The sacrificial cathodic protection of UNS C71500 heat exchanger tubes in Arabian Gulf sea water

    SciTech Connect

    Al-Hashem, A.; Carew, J.A.; Al-Sayegh, A.

    1997-12-01

    A laboratory investigation using a specially designed circulating test rig was carried out to study the effectiveness of achieving complete cathodic protection of UNS C71500 heat exchanger tubes in seawater applications. Results indicated that the galvanic current distribution covered the entire 6m length of the tube. The presence of sulfide ions as pollutants in seawater shifted the galvanic potentials of the tubes to more active potentials and prevented the formation of protective films that normally form.

  18. Protection of steel piles in harbours by using DZ tape and cathodic polarization

    NASA Astrophysics Data System (ADS)

    Dai, Zhongdao

    1987-12-01

    An anticorrosion method using wet DZ1 tape and electrochemical cathodic protection is suggested. The advantages of this method over internationally patented sealing techniques lie in its electrochemically open system, high adsorption of OH- with resultant rise of pH, exchangeable electrolytes, simple pretreatment of the steel pipe, simplicity of application, lower cost, better protection even under ebb tide, and low transmission of oxygen and corrosion products.

  19. Hydrogen Induced Stress Cracking of Materials Under Cathodic Protection

    NASA Astrophysics Data System (ADS)

    LaCoursiere, Marissa P.

    Hydrogen embrittlement of AISI 4340, InconelRTM 718, Alloy 686 and Alloy 59 was studied using slow strain rate tests of both smooth and notched cylindrical specimens. Two heat treatments of the AISI 4340 material were used as a standard for two levels of yield strength: 1479 MPa, and 1140 MPa. A subset of the 1140 MPa AISI 4340 material also underwent plasma nitriding. The InconelRTM 718 material was hardened following AMS 5663M to obtain a yield strength of 1091 MPa. The Alloy 686 material was obtained in the Grade 3 condition with a minimum yield strength of 1034 MPa. The Alloy 59 material was obtained with a cold worked condition similar to the Alloy 686 and with a minimum yield strength of 1034 MPa. Ninety-nine specimens were tested, including smooth cylindrical tensile test specimens and smooth and notched cylindrical slow strain rate tensile tests specimens. Testing included specimens that had been precharged with hydrogen in 3.5% NaCl at 50°C for 2 weeks (AISI 4340), 4 weeks (InconelRTM 718, Alloy 686, Alloy 59) and 16 weeks (InconelRTM 718, Alloy 686, Alloy 59) using a potentiostat to deliver a cathodic potential of -1100 mV vs. SCE. The strain rate over the gauge section for the smooth specimens and in the notch root for the notched specimens was 1 x 10-6 /s. It was found that the AISI 4340 was highly embrittled in simulated ocean water when compared to the nickel based superalloys. The higher strength AISI 4340 showed much more embrittlement, as expected. Testing of the AISI 4340 at both 20°C and 4°C showed that the temperature had no effect on the hydrogen embrittlement response. The InconelRTM 718 was highly embrittled when precharged, although it only showed low levels of embrittlement when unprecharged. Both the Alloy 686 and Alloy 59 showed minimal embrittlement in all conditions. Therefore, for the materials examined, the use of Alloy 686 and Alloy 59 for components in salt water environments when under a cathodic potential of -1100 mV vs. SCE is

  20. Effect of Alternating Current on the Cathodic Protection and Interface Structure of X80 Steel

    PubMed Central

    Wang, Huiru; Du, Cuiwei; Liu, Zhiyong; Wang, Luntao; Ding, De

    2017-01-01

    This study employs potential-monitoring techniques, cyclic voltammetry tests, alternating current (AC) voltammetry methods, and surface characterization to investigate the AC corrosion of cathodically protected X80 pipeline steel. In a non-passive neutral solution at pH 7.2, a sufficiently negative potential completely protects steel at an AC current density of 100 A/m2. In an alkaline solution at pH 9.6, more serious AC corrosion occurs at more negative cathodic protection (CP) potential, whereas without CP the steel suffers negligible corrosion. In addition, the interface capacitance increases with AC amplitude. Based on these results, the AC corrosion mechanisms that function under various conditions are analyzed and described. PMID:28773211

  1. Electrocatalysis paradigm for protection of cathode materials in high-voltage lithium-ion batteries

    SciTech Connect

    Shkrob, Ilya A.; Abraham, Daniel P.

    2016-07-06

    A new mechanistic framework is suggested to account for the protective action of certain electrolyte additives on high-voltage positive electrode (cathode) materials. The mechanism involves inactivation of catalytically active centers on the electrode active materials through fragmentation reactions involving molecules at its surface. The cathode protection additives oxidize before the solvent and serve as sacrificial inhibitors of the catalytic centers. Without the additive, the surface oxidation of the solvent (like solvent oxidation in the bulk) yields H loss radicals and releases the proton that can combine with anions forming corrosive acids. This proton-release reaction is demonstrated experimentally for boronate additives. Specific radical reactions for the latter additives on the electrode surface are suggested. Furthermore, the same approach can be used to rationalize the protective action of other additives and account for various observations regarding their performance.

  2. Electrocatalysis paradigm for protection of cathode materials in high-voltage lithium-ion batteries

    SciTech Connect

    Shkrob, Ilya A.; Abraham, Daniel P.

    2016-07-06

    A new mechanistic framework is suggested to account for the protective action of certain electrolyte additives on high-voltage positive electrode (cathode) materials. The mechanism involves inactivation of catalytically active centers on the electrode active materials through fragmentation reactions involving molecules at its surface. The cathode protection additives oxidize before the solvent and serve as sacrificial inhibitors of the catalytic centers. Without the additive, the surface oxidation of the solvent (like solvent oxidation in the bulk) yields H loss radicals and releases the proton that can combine with anions forming corrosive acids. This proton-release reaction is demonstrated experimentally for boronate additives. Specific radical reactions for the latter additives on the electrode surface are suggested. Furthermore, the same approach can be used to rationalize the protective action of other additives and account for various observations regarding their performance.

  3. Electrocatalysis paradigm for protection of cathode materials in high-voltage lithium-ion batteries

    DOE PAGES

    Shkrob, Ilya A.; Abraham, Daniel P.

    2016-07-06

    A new mechanistic framework is suggested to account for the protective action of certain electrolyte additives on high-voltage positive electrode (cathode) materials. The mechanism involves inactivation of catalytically active centers on the electrode active materials through fragmentation reactions involving molecules at its surface. The cathode protection additives oxidize before the solvent and serve as sacrificial inhibitors of the catalytic centers. Without the additive, the surface oxidation of the solvent (like solvent oxidation in the bulk) yields H loss radicals and releases the proton that can combine with anions forming corrosive acids. This proton-release reaction is demonstrated experimentally for boronate additives.more » Specific radical reactions for the latter additives on the electrode surface are suggested. Furthermore, the same approach can be used to rationalize the protective action of other additives and account for various observations regarding their performance.« less

  4. Preliminary Investigation of Ceramic-Coated Anodes for Cathodic Protection.

    DTIC Science & Technology

    1983-08-01

    used Electrodes," Journal De Physique, Vol 4. p CI (1977) R. Itai and anodes that are either inexpensive and very large, or H. Kunai, U.S. Patent No...have been made to manu- protection system anodes was only begun recently. facture anodes coated with magnetite. Itai and Kanai Two types of systems

  5. Stainless steels can be cathodically protected using energy stored at the marine sediment/seawater interface.

    PubMed

    Orfei, Leda H; Simison, Silvia; Busalmen, Juan Pablo

    2006-10-15

    Laboratory-scale experiments were performed in which the corrosion protection of stainless steels in seawater was afforded by cathodic protection. The method was implemented for the first time using the potential difference at the marine sediment/seawater interface as the only source of electric power. Graphite electrodes buried in marine sediment, developing a potential of -0.45 V versus a saturated calomel electrode (SCE), were used as anodes to cathodically polarize UNS S30403 stainless steel coupons that were exposed to seawater. The cathodic protection system was operated with low polarization of stainless steel, typically to -0.2 V (vs SCE) and was found to properly prevent material failure even in the presence of a well-developed biofilm. With voltammetry, the protection current was found to be related to the oxidation of reduced sulfur compounds in the sediments. Results demonstrate that this inexpensive and environmentally friendly method can, so far, extend the service life of stainless steels in seawater.

  6. Impressed current cathodic protection of a caisson structure for arctic conditions

    SciTech Connect

    Willis, A.D. Ltd., Bowesfield Lane, Stockton on Tees, Cleveland TS18 3HQ ); Lingnau, D.G. )

    1988-11-01

    The search for new commercial oil production has led to exploration for the first offshore fields within the arctic circle. The cathodic protection of structures capable of withstanding sea ice floes of 4-m (12-ft) thick presents the corrosion engineer with a new challenge. The design consideration for an external corrosion prevention system on a permanent caisson structure (Molikpaq) deployed for a 20-year service life are reviewed both in terms of the cathodic protection requirement and the mechanical considerations. This article describes a practical system adopted as a solution to these challenges. the rationale is also detailed for selecting the maximum current output for the system, materials for anodes, dielectric shields and reference electrodes, along with the methods used in installation. Data obtained during the commissioning of the system is included, as well as values of output current and potential from the fixed control electrodes during the systems's initial month of operation at an offshore drilling unit. The system not only achieved protection of the external immersed surfaces, but also full cathodic protection in the central core area filled with aggregate.

  7. The past and future of cathodic protection for underground storage tanks

    SciTech Connect

    Lehmann, J.A. )

    1994-05-01

    Corrosion protection for underground storage tanks (USTs) has become a vital national consideration since the establishment of new US Environmental Protection Agency (EPA) rules. Compliance with these rules is required by the end of 1998. Approximately 700,000 buried steel tanks in the United States are likely candidates for cathodic protection (CP) to meet regulatory compliance. This review of CP and other corrosion control measures used on USTs will help tank owners and corrosion control professionals make plans to meet the EPA deadline before the last-minute rush begins.

  8. The long term effects of cathodic protection on corroding, pre-stressed concrete structures: Hydrogen embrittlement of the reinforcing steel

    NASA Astrophysics Data System (ADS)

    Enos, David George

    Assessment of the effect of cathodic protection on a chloride contaminated bridge pile involves the definition of the hydrogen embrittlement behavior of the pearlitic reinforcement combined with quantification of the local (i.e., at the steel/concrete interface) chemical and electrochemical conditions, both prior to and throughout the application of cathodic protection. The hydrogen embrittlement behavior of the reinforcement was assessed through a combination of Devanathan/Stachurski permeation experiments to quantify subsurface hydrogen concentrations, CsbH, as a function of the applied hydrogen overpotential, eta, and crack initiation tests for bluntly notched and fatigue pre-cracked tensile specimens employing elastic-plastic finite element analysis and linear elastic fracture mechanics, respectively. A threshold mobile lattice hydrogen concentration for embrittlement of 2×10sp{-7} mol/cmsp3 was established for bluntly notched and fatigue pre-cracked specimens. Crack initiation occurred by the formation of shear cracks oriented at an angle approaching 45sp° from the tensile axis, as proposed by Miller and Smith (Miller, 1970), in regions where both the longitudinal and shear stresses were maximized (i.e., near the notch root). These Miller cracks then triggered longitudinal splitting which continued until fast fracture of the remaining ligament occurred. Instrumented laboratory scale piles were constructed and partially immersed in ASTM artificial ocean water. With time, localized corrosion (crevicing) was initiated along the reinforcement, and was accompanied by an acidic shift in the pH of the occluded environment due to ferrous ion hydrolysis. Cathodic protection current densities from -0.1 muA/cmsp2 to -3.0 muA/cmsp2 were applied via a skirt anode located at the waterline. Current densities as low as 0.66 muA/cmsp2 were sufficient to deplete the dissolved oxygen concentration at the steel/concrete interface and result in the observance of hydrogen

  9. Demonstration of Cathodic Protection Systems for Utilities in Severely Corrosive Environments at Fort Jackson

    DTIC Science & Technology

    2009-08-01

    permanent copper - copper sulfate reference electrode. If the coupon reading is -850 mV or more negative (this value can be set higher or lower by the...6. Solid perforated pipe to be located at anode depth, solid pipe above anodes, and small vent pipe entire length of column...aluminum and copper which have different criteria for cathodic protection than that used on buried steel pipe. A new ceramic mixed metal oxide

  10. Continuing life test of a xenon hollow cathode for a space plasma contactor

    NASA Technical Reports Server (NTRS)

    Sarver-Verhey, Timothy R.

    1994-01-01

    Implementation of a hollow cathode plasma contactor for charge control on the Space Station has required validation of long-life hollow cathodes. A test series of hollow cathodes and hollow cathode plasma contactors was initiated as part of the plasma contactor development program. An on-going wear-test of a hollow cathode has demonstrated cathode operation in excess of 10,000 hours with small changes in operating parameters. The discharge has experienced 10 shutdowns during the test, all of which were due to test facility failures or expellant replenishment. In all cases, the cathode was re-ignited at approximately 42 volts and resumed typical operation. This test represents the longest demonstrated stable operation of a high current (greater than 1 A) xenon hollow cathode reported to date.

  11. Continuous treatment of high strength wastewaters using air-cathode microbial fuel cells.

    PubMed

    Kim, Kyoung-Yeol; Yang, Wulin; Evans, Patrick J; Logan, Bruce E

    2016-12-01

    Treatment of low strength wastewaters using microbial fuel cells (MFCs) has been effective at hydraulic retention times (HRTs) similar to aerobic processes, but treatment of high strength wastewaters can require longer HRTs. The use of two air-cathode MFCs hydraulically connected in series was examined to continuously treat high strength swine wastewater (7-8g/L of chemical oxygen demand) at an HRT of 16.7h. The maximum power density of 750±70mW/m(2) was produced after 12daysof operation. However, power decreased by 85% after 185d of operation due to serious cathode fouling. COD removal was improved by using a lower external resistance, and COD removal rates were substantially higher than those previously reported for a low strength wastewater. However, removal rates were inconsistent with first order kinetics as the calculated rate constant was an order of magnitude lower than rate constant for the low strength wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Thermal-sprayed zinc anodes for cathodic protection of steel-reinforced concrete bridges

    SciTech Connect

    Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; McGill, Galen E.

    1996-01-01

    Thermal-sprayed zinc anodes are being used in Oregon in impressed current cathodic protection (ICCP) systems for reinforced concrete bridges. The U.S. Department of Energy, Albany Research Center, is collaborating with the Oregon Department of Transportation (ODOT) to evaluate the long-term performance and service life of these anodes. Laboratory studies were conducted on concrete slabs coated with 0.5 mm (20 mil) thick, thermal-sprayed zinc anodes. The slabs were electrochemically aged at an accelerated rate using an anode current density of 0.032 A/m2 (3mA/ft2). Half the slabs were preheated before thermal-spraying with zinc; the other half were unheated. Electrochemical aging resulted in the formation at the zinc-concrete interface of a thin, low pH zone (relative to cement paste) consisting primarily of ZnO and Zn(OH)2, and in a second zone of calcium and zinc aluminates and silicates formed by secondary mineralization. Both zones contained elevated concentrations of sulfate and chloride ions. The original bond strength of the zinc coating decreased due to the loss of mechanical bond to the concrete with the initial passage of electrical charge (aging). Additional charge led to an increase in bond strength to a maximum as the result of secondary mineralization of zinc dissolution products with the cement paste. Further charge led to a decrease in bond strength and ultimately coating disbondment as the interfacial reaction zones continued to thicken. This occurred at an effective service life of 27 years at the 0.0022 A/m2 (0.2 mA/ft2) current density typically used by ODOT in ICCP systems for coastal bridges. Zinc coating failure under tensile stress was primarily cohesive within the thickening reaction zones at the zinc-concrete interface. There was no difference between the bond strength of zinc coatings on preheated and unheated concrete surfaces after long service times.

  13. Cathodes with intrinsic redox overcharge protection: A new strategy towards safer Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Wen, Jian-Wu; Zhang, Da-Wei; Chen, Chun-Hua; Ding, Chu-Xiong; Yu, Yan; Maier, Joachim

    2014-10-01

    Overcharge safety is the most crucial problem facing especially large-sized lithium-ion batteries (LIBs) packs owing to the inevitable inhomogeneity of charge-state for each cell. We propose a fresh safety strategy to avoid overcharging, i.e. the use of a solid-state anti-overcharge additive to perform an intrinsic overcharge protection. The mechanism is triggered from a solid-state composite cathode obtained by typically mixing a pre-selected transition-metal oxide with a certain cathodes thus constituting a composite cathode. The effectiveness of this strategy is demonstrated with an example of LiCoO2/CuO (95:5 by weight) composite, which exhibits high-potential (up to 5 V vs. Li+/Li) and long-period (month-level) anti-overcharge performance. It is found that the additive does not hurt the electrochemical cycling performance under normal operational conditions. This novel safety strategy is simple and flexible, which may open a new window to develop safer LIBs systems.

  14. Electrochemical measurements of cathodic protection for reinforced concrete piles in a marine environment using embedded corrosion monitoring sensors

    NASA Astrophysics Data System (ADS)

    Jeong, Jin-A.; Chung, Won-Sub; Kim, Yong-Hwan

    2013-05-01

    This study developed a sensor to monitor the corrosion of reinforced concrete structures. Concrete pile specimens with embedded sensors were used to obtain data on corrosion and cathodic protection for bridge columns in a real marine environment. Corrosion potential, cathodic protection current density, concrete resistivity, and the degree of depolarization potential were measured with the embedded sensors in concrete pile specimens. The cathodic protection (CP) state was accurately monitored by sensors installed in underwater, tidal, splash, and atmospheric zones. The protection potential measurements confirmed that the CP by Zn-mesh sacrificial anode was fairly effective in the marine pile environment. The protection current densities in the tidal, splash zones were 2-3 times higher than those in underwater and atmospheric zones. The concrete resistivity in the tidal and splash zones was decreased through the installation of both mortar-embedded Zn-mesh (sacrificial anode) and outside an FRP jacket (cover). Considering the CP, the cathodic prevention was more effective than cathodic protection.

  15. Cathodic protection of steel by electrodeposited zinc-nickel alloy coatings

    SciTech Connect

    Baldwin, K.R.; Smith, C.J.E.; Robinson, M.J.

    1995-12-01

    The ability of electrodeposited zinc-nickel alloy coatings to cathodically protect steel was studied in dilute chloride solutions. The potential distribution along steel strips partly electroplated with zinc-nickel alloys was determined, and the length of exposed steel that was held below the minimum protection potential (E{sub prot}) was taken as a measure of the level of cathodic protection (CP) provided by the alloy coatings. The level of CP afforded by zinc alloy coatings was found to decrease with increasing nickel content. When nickel content was increased to {approx} {ge} 21 wt%, no CP was obtained. Surface analysis of uncoupled zinc-nickel alloys that were immersed in sodium chloride (NaCl) solutions showed the concentration of zinc decreased in the surface layers while the concentration of nickel increased, indicating that the alloys were susceptible to dezincification. The analysis of zinc-nickel alloy coatings on partly electroplated steel strips that were immersed in chloride solution showed a significantly higher level of dezincification than that found for uncoupled alloy coatings. This effect accounted for the rapid loss of CP afforded to steel by some zinc alloy coatings, particularly those with high initial nickel levels.

  16. Cathodic protection of prestressed concrete bridge pilings in a marine environment

    SciTech Connect

    Scannell, W.T.; Sohanghpurwala, A.A.; Powers, R.G.; Hartt, W.H.

    1994-12-31

    Cathodic protection (CP) is the only recognized technique for arresting ongoing corrosion of conventional mild reinforcing steel in concrete. This paper discusses the present state of knowledge regarding the applicability of this technology to prestressing steel. Practical and technical issues to consider in selecting a CP system for prestressed concrete bridge pilings in a marine environment are discussed. The design parameters for the first full scale installation of CP on over 170 prestressed concrete bridge pilings in a marine environment are presented. Performance data obtained on the selected CP system from other small scale installations are also presented.

  17. Humectants To Augment Current From Metallized Zinc Cathodic Protection Systems on Concrete

    SciTech Connect

    Holcomb, Gordon R.; Covino Jr., Bernard S.; Cramer, Stephen D.; Russell, James H. Russell; Bullard, Sophie J.; Collins, W. Keith; Bennett, Jack E.; Soltesz, Steven M.; Laylor, H. Martin

    2002-12-01

    Cathodic protection (CP) systems using thermal-sprayed zinc anodes are employed to mitigate the corrosion process in reinforced concrete structures. However, the performance of the anodes is improved by moisture at the anode-concrete interface. Research was conducted to investigate the effect of hydrophilic chemical additives, humectants, on the electrical performance and service life of zinc anodes. Lithium bromide and lithium nitrate were identified as feasible humectants with lithium bromide performing better under galvanic CP and lithium nitrate performing better under impressed current CP. Both humectants improved the electrical operating characteristics of the anode and increased the service life by up to three years.

  18. Cathodic protection survey of deep-water structures and subsea installations

    SciTech Connect

    Leask, L.J. )

    1989-11-01

    The successful and efficient cathodic protection (CP) survey of a deep water structure using a remotely operated vehicle (ROV) has remained an enigma to many corrosion engineers in oil companies. The location of the corrosion group within the company structure often plays a major role in the success of the project. Operators locate their corrosion departments in different groups, some in the offshore/onshore operations and others in the design group. This location often has a bearing on the financial and operational approach to the project. The author discusses how a successful CP survey is both an achievable and exciting project with experienced preplanning and selection of the correct equipment.

  19. Protective sheath for a continuous measurement thermocouple

    DOEpatents

    Phillippi, R.M.

    1991-12-03

    Disclosed is a protective thermocouple sheath of a magnesia graphite refractory material for use in continuous temperature measurements of molten metal in a metallurgical ladle and having a basic slag layer thereon. The sheath includes an elongated torpedo-shaped sheath body formed of a refractory composition and having an interior borehole extending axially therethrough and adapted to receive a thermocouple. The sheath body includes a lower end which is closed about the borehole and forms a narrow, tapered tip. The sheath body also includes a first body portion integral with the tapered tip and having a relatively constant cross section and providing a thin wall around the borehole. The sheath body also includes a second body portion having a relatively constant cross section larger than the cross section of the first body portion and providing a thicker wall around the borehole. The borehole terminates in an open end at the second body portion. The tapered tip is adapted to penetrate the slag layer and the thicker second body portion and its magnesia constituent material are adapted to withstand chemical attack thereon from the slag layer. The graphite constituent improves thermal conductivity of the refractory material and, thus, enhances the thermal responsiveness of the device. 4 figures.

  20. Protective sheath for a continuous measurement thermocouple

    DOEpatents

    Phillippi, R. Michael

    1991-01-01

    Disclosed is a protective thermocouple sheath of a magnesia graphite refractory material for use in continuous temperature measurements of molten metal in a metallurgical ladle and having a basic slag layer thereon. The sheath includes an elongated torpedo-shaped sheath body formed of a refractory composition and having an interior borehole extending axially therethrough and adapted to receive a thermocouple. The sheath body includes a lower end which is closed about the borehole and forms a narrow, tapered tip. The sheath body also includes a first body portion integral with the tapered tip and having a relatively constant cross section and providing a thin wall around the borehole. The sheath body also includes a second body portion having a relatively constant cross section larger than the cross section of the first body portion and providing a thicker wall around the borehole. The borehole terminates in an open end at the second body portion. The tapered tip is adapted to penetrate the slag layer and the thicker second body portion and its magnesia constituent material are adapted to withstand chemical attack thereon from the slag layer. The graphite constituent improves thermal conductivity of the refractory material and, thus, enhances the thermal responsiveness of the device.

  1. Protective sheath for a continuous measurement thermocouple

    SciTech Connect

    Phillippi, R.M.

    1991-12-03

    Disclosed is a protective thermocouple sheath of a magnesia graphite refractory material for use in continuous temperature measurements of molten metal in a metallurgical ladle and having a basic slag layer thereon. The sheath includes an elongated torpedo-shaped sheath body formed of a refractory composition and having an interior borehole extending axially therethrough and adapted to receive a thermocouple. The sheath body includes a lower end which is closed about the borehole and forms a narrow, tapered tip. The sheath body also includes a first body portion integral with the tapered tip and having a relatively constant cross section and providing a thin wall around the borehole. The sheath body also includes a second body portion having a relatively constant cross section larger than the cross section of the first body portion and providing a thicker wall around the borehole. The borehole terminates in an open end at the second body portion. The tapered tip is adapted to penetrate the slag layer and the thicker second body portion and its magnesia constituent material are adapted to withstand chemical attack thereon from the slag layer. The graphite constituent improves thermal conductivity of the refractory material and, thus, enhances the thermal responsiveness of the device. 4 figures.

  2. Corrosion control acceptance criteria for sacrificial anode type, cathodic protection systems (user guide)

    NASA Astrophysics Data System (ADS)

    Hock, Vincent F.; Noble, Michael; McLeod, Malcolm E.

    1994-07-01

    The Army currently operates and maintains more than 20,000 underground storage tanks and over 3000 miles of underground gas pipelines, all of which require some form of corrosion control. Cathodic protection is one method of corrosion control used to prevent corrosion-induced leaks when a steel structure is exposed to an aggressive soil. The corrosion control acceptance criteria for sacrificial anode type CP systems provides guidelines for the DEH/DPW cathodic protection installation inspectors whose responsibilities are to ensure that the materials and equipment specified are delivered to the job site and subsequently installed in accordance with the engineering drawings and specifications. The sacrificial anode CP acceptance criteria includes all components for the sacrificial anode system such as insulated conductors, anodes, anode backfills, and auxiliary equipment. The sacrificial anode CP acceptance criteria is composed of a checklist that lists each component and that contains a space for the inspector to either check 'yes' or 'no' to indicate whether the component complies with the job specifications. In some cases, the inspector must measure and record physical dimensions or electrical output and compare the measurements to standards shown in attached tables.

  3. Hydrogen Assisted Crack in Dissimilar Metal Welds for Subsea Service under Cathodic Protection

    NASA Astrophysics Data System (ADS)

    Bourgeois, Desmond

    Dissimilar metal welds (DMWs) are routinely used in the oil and gas industries for structural joining of high strength steels in order to eliminate the need for post weld heat treatment (PWHT) after field welding. There have been reported catastrophic failures in these DMWs, particularly the AISI 8630 steel - Alloy 625 DMW combination, during subsea service while under cathodic protection (CP). This is due to local embrittlement that occurs in susceptible microstructures that are present at the weld fusion boundary region. This type of cracking is known as hydrogen assisted cracking (HAC) and it is influenced by base/filler metal combination, and welding and PWHT procedures. DMWs of two material combinations (8630 steel -- Alloy 625 and F22 steel -- Alloy 625), produced with two welding procedures (BS1 and BS3) in as welded and PWHT conditions were investigated in this study. The main objectives included: 1) evaluation of the effect of materials composition, welding and PWHT procedures on the gradients of composition, microstructure, and properties in the dissimilar transition region and on the susceptibility to HAC; 2) investigation of the influence of microstructure on the HAC failure mechanism and identification of microstructural constituents acting as crack nucleation and propagation sites; 3) assessment of the applicability of two-step PWHT to improve the resistance to HAC in DMWs; 4) establishment of non-failure criterion for the delayed hydrogen cracking test (DHCT) that is applicable for qualification of DMWs for subsea service under cathodic protection (CP).

  4. Cathodic protection parameters measured on corrosion coupons and pipes buried in the field

    SciTech Connect

    Barlo, T.J.

    1998-12-31

    There is renewed interest in the use of corrosion coupons for monitoring catholically protected pipelines. The resurgence in interest was prompted by the need to determine the {minus}850 mV (Cu/CuSO{sub 4}) polarized potential recommended by NACE International RP0169-96 where traditional methods (e.g., current interruption) may not be feasible or practical. A variety of coupon sizes, shapes, orientations, and means of measurement have been developed over the years, with many in use today around the world. The results from a field study on operating pipelines using coupons of two different sizes (49 and 4.2 cm{sup 2}) in two widely different soil environments are presented, and correlations between the cathodic protection parameters of on-potential, instant-off potential, IR drop, and polarization on the coupons and pipes are discussed. Factors controlling the relationships are analyzed and some limitations in the use of coupons are considered.

  5. 39 CFR 3007.61 - Continued effectiveness of protective conditions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Continued effectiveness of protective conditions... MATERIALS PROVIDED BY THE POSTAL SERVICE § 3007.61 Continued effectiveness of protective conditions. (a) If... protective conditions at least as effective as those set forth in the Commission order establishing...

  6. Continuous electricity generation in stacked air cathode microbial fuel cell treating domestic wastewater.

    PubMed

    Choi, Jeongdong; Ahn, Youngho

    2013-11-30

    This study examined the continuous performance of air cathode MFC stacks for domestic wastewater treatments at two different temperatures (23 ± 3 °C and 30 ± 1 °C) and organic loading rates to determine the effects of the electrode connection and hydraulic flow mode on the stack performance. The power density and process stability were affected significantly by the electrode connection type, flow mode, and operating parameters. The parallel electrode connection system (in series flow mode) had benefits of COD removal, Coulombic efficiency and maximal power density due to the higher stability of the ORP in overall cells. The highest power density of 420 mW/m(2) (12.8 W/m(3)) was achieved in series flow and parallel connection mode at an organic loading rate of 25.6 g COD/L-d (HRT of 0.33 h) under mesophilic conditions, achieving a COD removal of 44%. The results highlight the importance of prefermentation process in the application of a stacked MFC for an actual wastewater treatment.

  7. Long-term effects of cathodic protection on prestressed concrete structures: Hydrogen embrittlement of prestressing steel

    SciTech Connect

    Enos, D.G.; Williams, A.J. Jr.; Scully, J.R.

    1997-11-01

    The issue of safe cathodic protection (CP) limits for prestressing steel in concrete was addressed in regard to concerns over hydrogen embrittlement (HE). The local environment at the steel-concrete interface was found to vary as a function of vertical position within a laboratory-scale marine bridge piling. Embedded pH electrodes indicated the pH within a steel crevice embedded within a concrete piling decreased from 11.5 to 6.5 in the atmospheric zone 30.5 cm (12 in.) above the water line. Hydrogen permeation was detected using embedded sensors at applied potentials (E{sub app}) more positive than the reversible potential for hydrogen production calculated for alkaline pore solutions (pH > 12.6). A safe limit based on the reversible electrode potential (REP) would require knowledge of pH and E{sub app} as a function of vertical position, as well as an understanding of their influence on HE. Constant extension rate tensile testing (CERT) was performed on notched prestressing steel tensile specimens at various cathodic polarization levels in: (1) saturated calcium hydroxide (Ca[OH]{sub 2}), (2) ASTM artificial ocean water, (3) under a mortar cover in artificial ocean water, and (4) in pH 4 and pH 6 Ca{sup 2+}-containing environments simulating ferrous ion hydrolysis on corroding prestressing steel. CERT results were combined with permeation measurements to determine the relationship between steel mobile hydrogen concentration (C{sub H}) and fracture initiation stress ({sigma}{sub i}) in each environment over a series of cathodic potentials.

  8. Continuous flow membrane-less air cathode microbial fuel cell with spunbonded olefin diffusion layer.

    PubMed

    Tugtas, Adile Evren; Cavdar, Pelin; Calli, Baris

    2011-11-01

    The power production performance of a membrane-less air-cathode microbial fuel cell was evaluated for 53 days. Anode and cathode electrodes and the micro-fiber cloth separator were configured by sandwiching the separator between two electrodes. In addition, the air-facing side of the cathode was covered with a spunbonded olefin sheet instead of polytetrafluoroethylene (PTFE) coating to control oxygen diffusion and water loss. The configuration resulted in a low resistance of about 4Ω and a maximum power density of 750 mW/m2. However, as a result of a gradual decrease in the cathode potential, maximum power density decreased to 280 mW/m2. The declining power output was attributed to loss of platinum catalyst (8.26%) and biomass growth (38.44%) on the cathode. Coulombic efficiencies over 55% and no water leakage showed that the spunbonded olefin sheet covering the air-facing side of the cathode can be a cost-effective alternative to PTFE coating.

  9. Compact lanthanum hexaboride hollow cathode.

    PubMed

    Goebel, Dan M; Watkins, Ronald M

    2010-08-01

    A compact lanthanum hexaboride hollow cathode has been developed for space applications where size and mass are important and research and industrial applications where access for implementation might be limited. The cathode design features a refractory metal cathode tube that is easily manufactured, mechanically captured orifice and end plates to eliminate expensive e-beam welding, graphite sleeves to provide a diffusion boundary to protect the LaB6 insert from chemical reactions with the refractory metal tube, and several heater designs to provide long life. The compact LaB(6) hollow cathode assembly including emitter, support tube, heater, and keeper electrode is less than 2 cm in diameter and has been fabricated in lengths of 6-15 cm for different applications. The cathode has been operated continuously at discharge currents of 5-60 A in xenon. Slightly larger diameter versions of this design have operated at up to 100 A of discharge current.

  10. Influence of scale deposition on cathodic-protection performance in desalination plant conditions.

    PubMed

    Hodgkiess, T; Najm-Mohammed, N A

    2004-01-01

    This paper describes an investigation into the interrelationships between the performance of an impressed current cathodic protection (CP) system and the deposition of scale compounds in a seawater pipe system. Some experiments were conducted on a laboratory set-up but the emphasis was on tests on a 0.25 m diameter steel pipe fed by seawater flowing to a thermal desalination plant. The experimental approach involved monitoring the CP current as a function of time at various set potentials and correlating this data with evidence from visual inspection of the pipe-wall surfaces and small probe specimens. The influences of control potential and seawater flow rate at temperatures of 25-35 degrees C were studied. Selected scale samples were subjected to examination by scanning electron microscopy and X-ray diffraction. The overall findings are discussed in terms of fundamental scale/CP-operation interactions and aspects relevant to practical operation of CP systems on seawater pipe installations.

  11. Laboratory study on new cathodic protection criterion proposed for prestressed concrete

    SciTech Connect

    Wagner, J. Jr.; Funahashi, M.

    1994-12-31

    Bazzoni and Lazzari have proposed a new criterion for the cathodic protection of prestressed concrete. The criterion is based on the use of mixed metal-oxide-activated anodes which exhibit a stable polarized potential over a wide range of current densities when embedded in concrete. The criterion proposes that a ``safe`` anode/structure feeding voltage can be calculated that will both provide corrosion control in the area covered by the anode system and will prevent the steel reinforcement potential reaching values where hydrogen ions can be reduced to hydrogen and the consequent possibility of embrittlement of high strength prestressing members. This paper describes a laboratory study made to examine the validity of the proposed criterion. The results of the study appear to support criterion as both safe and effective for new prestressed concrete structures and possibly for existing structures as well.

  12. Performance of thermal-sprayed zinc anodes treated with humectants in cathodic protection systems

    SciTech Connect

    Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Holcomb, Gordon R.; Russell, James H.; Bennett, John E.; Milius, John K.; Cryer, Curtis B.; Soltesz, Steven M.

    2001-01-01

    Thermal-sprayed Zn anodes are used for impressed current cathodic protection (ICCP) systems in Oregon's reinforced concrete coastal bridges to minimize corrosion damage. Thermal-sprayed Zn performs well as an ICCP anode but the voltage requirement can increase with increasing electrochemical age. It also performs well as a galvanic (GCP) anode but current output can decrease with increasing electrochemical age. Past research has shown that increasing moisture at the Zn anode-concrete interface improves the operation of the thermal-sprayed Zn anode. Humectants, hygroscopic materials that are applied to the surface of the Zn-anode, can increase the moisture at the zinc-concrete interface, thereby improving the performance and extending the anode service life. Results are given for humectant-treated (LiBr and LiNO3) thermal-sprayed Zn anodes used in the laboratory electrochemical aging studies and in field studies on the Yaquina Bay Bridge, Oregon, USA.

  13. The slope parameter approach to marine cathodic protection design and its application to impressed current systems

    SciTech Connect

    Hartt, W.H.

    1999-07-01

    The recently developed slope parameter approach to design of galvanic anode cathodic protection (cp) systems for marine structures constitutes an advancement in this technology compared to current practice, primarily because the former is first principles based and the latter is an empirical algorithm. In this paper, the slope parameter approach is reviewed; and related applications for which it can be utilized, including (1) design of new and retrofit cp systems, (2) evaluation of potential survey data, and (3) cp system design for complex geometries, are mentioned. The design current density is identified as the single remaining parameter for which values must be projected solely by experience or experimentation. In addition, the slope parameter approach is applied to the results of impressed current cp experiments, and it is shown how parameters for this can be interrelated with those of galvanic anode cp. Advantages of this capability are identified and discussed.

  14. Relative contribution of set cathode potential and external mass transport on TCE dechlorination in a continuous-flow bioelectrochemical reactor.

    PubMed

    Verdini, Roberta; Aulenta, Federico; de Tora, Francesca; Lai, Agnese; Majone, Mauro

    2015-10-01

    Microbial bioelectrochemical systems, which use solid-state cathodes to drive the reductive degradation of contaminants such as the chlorinated hydrocarbons, are recently attracting considerable attention for bioremediation applications. So far, most of the published research has focused on analyzing the influence of key (bio)electrochemical factors influencing contaminant degradation, such as the cathode potential, whereas only few studies have examined the potential impact of mass transport phenomena on process performance. Here we analyzed the performance of a flow-through bioelectrochemical reactor, continuously fed with a synthetic groundwater containing trichloroethene at three different linear fluid velocities (from 0.3 m d(-1) to 1.7 m d(-1)) and three different set cathode potentials (from -250 mV to -450 mV vs. the standard hydrogen electrode). The obtained results demonstrated that, in the range of fluid velocities which are characteristics for natural groundwater systems, mass transport phenomena may strongly influence the rate and extent of reductive dechlorination. Nonetheless, the relative importance of mass transport largely depends on the applied cathode potential which, in turn, controls the intrinsic kinetics of biological reactions and the underlying electron transfer mechanisms.

  15. Influence of fouling on the efficiency of sacrificial anodes in providing cathodic protection in Southeast Asian tropical seawater.

    PubMed

    Blackwood, D J; Lim, C S; Teo, S L M

    2010-10-01

    Aluminum and zinc based sacrificial anodes are routinely used to provide corrosion protection to metals (typically steel) exposed to seawater, for example in steel pipelines and storage tanks. However, the high fouling rates experienced in South East Asia means that both the anodes and the metals to be protected rapidly become coated with macrofoulers, which could potentially prevent the anodes from being effective. The present study, involving exposure tests of up to 18 months, indicates that both aluminum and zinc sacrificial anodes remain effective even after being completely coated with biofouling. Furthermore, it was easier to remove the biofouling on the cathodically protected samples than on their unprotected counterparts, possibly due to the higher local pH produced by cathodic protection at the metal and seawater interface.

  16. Use of Molten Salt Fluxes and Cathodic Protection for Preventing the Oxidation of Titanium at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Schwandt, Carsten; Fray, Derek J.

    2014-12-01

    The current study demonstrates that it is possible to protect both solid and liquid titanium and titanium alloys from attack from air by cathodically polarizing the titanium component using an electro-active high-temperature molten salt flux and a moderate polarization potential. The electrolytic cell used comprises a cathode of either solid titanium or liquid titanium alloy, an electrolyte based on molten calcium chloride or fluoride salt, and an anode consisting of an inert oxygen-evolving material such as iridium metal. The new approach renders possible the processing of titanium at elevated temperatures in the presence of oxygen-containing atmospheres.

  17. EXPERIMENTAL STUDY ON EFFECTS OF CATHODIC PROTECTION TO PREVENT MACRO-CELL CORROSION OF STEEL IN CONCRETE

    NASA Astrophysics Data System (ADS)

    Yamamoto, Satoru; Ueno, Moe; Ishii, Kouji; Seki, Hiroshi

    Reinforcing bars embedded in concrete tend to corrode due to salt attack under marine environments. Corrosion of bars might be often caused with phenomenon of macro-cell. Cathodic protection has been, so far, applied to control the corrosion of reinforcing bars in RC members. In order to make clear the mechanisms of macro-cell corr osion and the effect of cathodic protecti on, laboratory tests were carried out. Testing concrete specimens contained two reinforcing bars which were buried at upper area of specimens and at lower area of ones, respectively. Lower zone of the concrete specimens were immersed in water. Testing results indicated as follows: (1) reinforci ng bars under wetting condition were anode and reinforcing bars under drying one cathode, (2) current density of macro-cell between two bars increased according as the potential difference increased and electric resistance of the concrete between two bars decreased, and (3) cathodic protection was effective to prevented macro-cell corrosion of reinforcing bars in concrete. Furthermore, it was presumed that corroded iron might be reduced to metal iron due to the protection current.

  18. Effect of formation of biofilms and chemical scale on the cathode electrode on the performance of a continuous two-chamber microbial fuel cell.

    PubMed

    Chung, Kyungmi; Fujiki, Itto; Okabe, Satoshi

    2011-01-01

    A two-chamber MFC system was operated continuously for more than 500 days to evaluate effects of biofilm and chemical scale formation on the cathode electrode on power generation. A stable power density of 0.57 W/m(2) was attained after 200 days operation. However, the power density decreased drastically to 0.2 W/m(2) after the cathodic biofilm and chemical scale were removed. As the cathodic biofilm and chemical scale partially accumulated on the cathode, the power density gradually recovered with time. Microbial community structure of the cathodic biofilm was analyzed based on 16S rRNA clone libraries. The clones closely related to Xanthomonadaceae bacterium and Xanthomonas sp. in the Gammaproteobacteria subdivision were most frequently retrieved from the cathodic biofilm. Results of the SEM-EDX analysis revealed that the cation species (Na(+) and Ca(2+)) were main constituents of chemical scale, indicating that these cations diffused from the anode chamber through the Nafion membrane. However, an excess accumulation of the biofilm and chemical scale on the cathode exhibited adverse effects on the power generation due to a decrease in the active cathode surface area and an increase in diffusion resistance for oxygen. Thus, it is important to properly control the formation of chemical scale and biofilm on the cathode during long-term operation.

  19. Design of impressed current cathodic protection (ICCP) systems for U.S. Navy hulls

    SciTech Connect

    Lucas, K.E.; Thomas, E.D.; Kaznoff, A.I.; Hogan, E.A.

    1999-07-01

    The goal of impressed current cathodic protection (ICCP) design for ship hulls, under the Navy Ship's Technical Manual (NSTM, Chapter 633), is to provide a uniform potential distribution at {minus}0.85 V, {+-}0.05 V, versus a silver/silver chloride (Ag/AgCl) reference cell, over the wetted hull surface during all operational aspects of an active ship. To accomplish this, the physical scale modeling (PSM) technique, combined with a rigid design protocol, has been used extensively by the US Navy to provide optimal and retrofit upgrade designs of ICCP systems for hulls. The ICCP design guidance, provided by the protocol, defines the hull properties, hull damage and general power supply requirements. PSM is utilized to determine optimal placement of ICCP components (anodes and reference cells) and to evaluate performance for up to a 15% wetted hull coatings loss under static (pierside) and dynamic (underway) conditions. Data are provided which illustrate the use of the design protocol criteria, along with the integrated PSM technique, to determine ICCP system design and evaluate performance.

  20. Application of Direct Assessment Approaches and Methodologies to Cathodically Protected Nuclear Waste Transfer Lines

    SciTech Connect

    Dahl, Megan M.; Pikas, Joseph; Edgemon, Glenn L.; Philo, Sarah

    2013-01-22

    The U.S. Department of Energy's (DOE) Hanford Site is responsible for the safe storage, retrieval, treatment, and disposal of approximately 54 million gallons (204 million liters) of radioactive waste generated since the site's inception in 1943. Today, the major structures involved in waste management at Hanford include 149 carbon steel single-shell tanks, 28 carbon-steel double-shell tanks, plus a network of buried metallic transfer lines and ancillary systems (pits, vaults, catch tanks, etc.) required to store, retrieve, and transfer waste within the tank farm system. Many of the waste management systems at Hanford are still in use today. In response to uncertainties regarding the structural integrity of these systems,' an independent, comprehensive integrity assessment of the Hanford Site piping system was performed. It was found that regulators do not require the cathodically protected pipelines located within the Hanford Site to be assessed by External Corrosion Direct Assessment (ECDA) or any other method used to ensure integrity. However, a case study is presented discussing the application of the direct assessment process on pipelines in such a nuclear environment. Assessment methodology and assessment results are contained herein. An approach is described for the monitoring, integration of outside data, and analysis of this information in order to identify whether coating deterioration accompanied by external corrosion is a threat for these waste transfer lines.

  1. Carbon fiber reinforced mortar as an electrical contact material for cathodic protection

    SciTech Connect

    Fu, X.; Chung, D.D.L.

    1995-05-01

    For a joint between old plain mortar and new mortar (which serves as an electrical contact material for cathodic protection of steel-reinforced old mortar), short carbon fiber addition to the new mortar was found to decrease both the contact resistivity and the new mortar`s volume resistivity. Whether the new mortar contained fibers or not, the contact resistance was higher than the new mortar`s volume resistance perpendicular to the contact and was lower than the new mortar`s volume resistance parallel to the contact. In the presence of latex, the volume resistivity was 3.1 {times} 10{sup 5}, 1.4 {times} 10{sup 3} and 1.2 {times} 10{sup 2} {Omega}{center_dot}cm and the contact resistivity was 5.9 {times} 10{sup 6}, 2.7 {times} 10{sup 5} and 2.6 {times} 10{sup 4} {Omega}{center_dot}cm{sup 2} at fiber contents of 0, 0.53 and 1.1 vol.% respectively. Latex addition alone to the new mortar increased slightly both contact resistivity and new mortar`s volume resistivity. All resistivities increased very slightly with curing age.

  2. Impressed-current cathodic protection of steel-reinforced concrete pilings: Protection criteria and the threshold for hydrogen embrittlement

    SciTech Connect

    Enos, D.G.; Williams, A.J. Jr.; Scully, J.R.; Clemena, G.G.

    1998-05-01

    Safe cathodic protection (CP) limits for prestressing steel in concrete and the adequacy of CP using established criteria were evaluated in regard to hydrogen embrittlement (HE). Impressed-current CP was applied to laboratory scale pilings at current densities from 0.1 {micro}A/cm{sup 2} to 3.0 {micro}A/cm{sup 2} via a skirt anode located at the waterline. Adequate CP was achieved at positions 25 cm (9.8 in.) above to 50 cm (19.7 in.) below the waterline, according to the 100-mV depolarization criterion, at an apparent applied current density of 0.33 {micro}A/cm{sup 2}. However, the {minus}780 mV{sub SCE} criterion was not met for currents as high as 1.33 {micro}A/cm{sup 2} for these positions. Hydrogen production, absorption, and permeation in steel first was observed via embedded hydrogen sensors 50 cm and 25 cm above the water line at an applied current density of 0.33 {micro}A/cm{sup 2}. Observation of hydrogen production verified concerns that the local oxygen concentration might be depleted readily at modest CP levels and that local pH levels may be below 12.5. Experimentation demonstrated that steel crevice corrosion was initiated readily within chloride (Cl{sup {minus}})-contaminated concrete prior to CP application and that this corrosion was accompanied by acidification of the local environment to pH {le} 6 as a result of ferrous ion (Fe{sup 2+}) hydrolysis. The mobile subsurface hydrogen concentration present within the steel reinforcement was determined for each applied cathodic current density. Although hydrogen production and uptake occurred at current densities as low as 0.33 {micro}A/cm{sup 2}, the critical hydrogen concentration for embrittlement (i.e., 2 {times} 10{sup {minus}7} mol H/cm{sup 3}, as determined in prior research for bluntly notched prestressing steel) was not exceeded at area averaged current densities <1.33 {micro}A/cm{sup 2}.

  3. Hydrothermal synthesis and photoelectrochemical performance enhancement of TiO2/graphene composite in photo-generated cathodic protection

    NASA Astrophysics Data System (ADS)

    Zhang, Weiwei; Guo, Hanlin; Sun, Haiqing; Zeng, Rong-Chang

    2016-09-01

    TiO2/graphene composites were synthesized through one-step hydrothermal method. The composites show an enhancement in photo-generated cathodic protection as the time-dependent profiles of photocurrent responses has confirmed. XRD data show that a bicrystalline framework of anatase and brookite formed as graphene provided donor groups in the hydrothermal process. The transfer of photoinduced electrons in the biphasic TiO2 results in effective electron-hole separation. Moreover, graphene lead to a negative shift of the Fermi level as evidenced by Mott-Schottky analysis, which decreases the Schottky barrier formed in the TiO2 and 304 stainless steel interface and results in the enhancement of photo-generated cathodic protection.

  4. Apollo/Saturn C00.00.19.3 operations and maintenance. Cathodic protection of communication cables

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Operating and maintenance instructions for cathodic protection of communication cables at the Cape Kennedy Launch Complex are presented. The system is designed to prevent or arrest corrosion of communication cables buried in soil or submerged in water by impressing sufficient direct current from the rectifier through the anodes to the cable. This process neutralizes or counteracts current flowing from the cable into the soil or water, thus preventing or arresting corrosion of the cable sheath material.

  5. A facile approach to derive binder protective film on high voltage spinel cathode materials against high temperature degradation

    NASA Astrophysics Data System (ADS)

    Chou, Wei-Yu; Jin, Yi-Chun; Duh, Jenq-Gong; Lu, Cheng-Zhang; Liao, Shih-Chieh

    2015-11-01

    The electrochemical performance of spinel LiNi0.5Mn1.5O4 cathode combined with different binders at elevated temperature is firstly investigated. The water soluble binder, such as sodium carboxymethyl cellulose (CMC) and sodium alginate (SA), is compared with the polyvinylidene difluoride (PVdF) binder used in non-aqueous process. The aqueous process can meet the need of Li-ion battery industry due to environmental-friendly and cost effectiveness by replacing toxic organic solvent, such as N-methyl-pyrrolidone (NMP). In this study, a significantly improved high temperature cycling performance is successfully obtained as compared to the traditional PVdF binder. The aqueous binder can serve as a protective film which inhibits the serious Ni and Mn dissolution especially at elevated temperature. Our result demonstrates a facile approach to solve the problem of capacity fading for high voltage spinel cathodes.

  6. Field Trial of impressed current, sacrificial anode, constant voltage and intermittent cathodic protection on a steel reinforced coastal bridge

    SciTech Connect

    Bullard, S.J.; Covino, B.S., Jr.; Williamson, K.M.; Holcomb, G.R.; Ziomek-Moroz, M.; Eden, D.A.; Cryer, C.B.; Tran, H.

    2007-03-01

    Equipment has been designed and installed for a field trial being conducted on a coastal reinforced concrete bridge with a newly installed cathodic protection (CP) system. The purpose of the field trial is to determine the optimum form of intermittent CP for protecting coastal bridges. The forms of CP that were considered for the field trial are: (1) impressed current CP as the control; (2) currentinterrupted ICCP; (3) corrosion rate monitoring device controlled ICCP; (4) constant voltage CP; and (5) sacrificial anode CP. Once the test is initiated, the performance of these four forms of CP on a coastal RC bridge and their effectiveness in providing protection to reinforcing steel will be is compared with that achieved by present Oregon Department of Transportation ICCP practices. Details are presented on the set up of the experiment and the logic used to control CP intermittently. The field trial is scheduled to be started early 2007.

  7. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... alkali on the metal surface. A voltage in excess of 1.20 volts may not be used unless previous test... not in contact with metals of different anodic potentials. (3) A minimum negative (cathodic... increase the pH at the metal surface, careful investigation or testing must be made before applying...

  8. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... alkali on the metal surface. A voltage in excess of 1.20 volts may not be used unless previous test... not in contact with metals of different anodic potentials. (3) A minimum negative (cathodic... increase the pH at the metal surface, careful investigation or testing must be made before applying...

  9. 49 CFR Appendix D to Part 192 - Criteria for Cathodic Protection and Determination of Measurements

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... I. Criteria for cathodic protection— A. Steel, cast iron, and ductile iron structures. (1) A... those across the structure-electrolyte boundary may suffer corrosion resulting from the build-up of... results indicate no appreciable corrosion will occur in the particular environment. (4) Since aluminum...

  10. Design and installation of a cathodic protection system for a large reinforced concrete intake structure in the Arabian Gulf

    SciTech Connect

    Ali, M.; Al-Ghannam, H.

    1997-09-01

    The paper describes the condition survey methodology, design and installation of a cathodic protection (C.P.) system for a large reinforced concrete reservoir and sea water intake structure. The structure is critical for the supply of cooling water for a 2.4 million metric ton steel plant. The C.P. System consisting of mixed metal oxide coating on titanium mesh type anodes and automatic voltage/current controlled rectifiers was successfully installed and has been operating within design guidelines for the past 15 months.

  11. Experience of cathodic protection, fabrication and installation of anodes for deep water pipelines in the North Sea and the Norwegian Sea

    SciTech Connect

    Eliassen, S.; Pettersen, N.H.

    1996-08-01

    Statoil is the major operator of the oil and gas pipelines in the North Sea and the Norwegian Sea. Different coating systems have been used for external corrosion protection of the pipelines. The paper presents the company`s experience regarding cathodic protection design and fabrication and installation of anodes for deep water pipelines.

  12. Fundamental advances for characterizing cathodic protection systems. Annual report, August 1993-July 1994

    SciTech Connect

    Srinivasan, R.; Gopalan, P.; Zarriello, P.R.; Murphy, J.C.

    1995-01-01

    In Part I of this report, corrosion of A109 steel in aerated aqueous 0.5% sodium chloride solution (ASTM-G-85) has been studied at the corrosion potential (Ecor) and at different cathodic polarization potentials. Optical microscopy is used to characterize localized corrosion. The Tone-Burst Faradaic Rectification (TBFR) instrumentation is described in Part II. Measurement of corrosion rates in steel that is under cathodic polarization is one of the main goals of this program. Although the authors have successfully demonstrated the capability of using faradaic rectification technique to measure corrosion rates in steel under CP, the presence of electrochemical and other low frequency noise has limited the use of this technique under most corrosion environments.

  13. Performance of Zinc Anodes for Cathodic Protection of Reinforced Concrete Bridges

    SciTech Connect

    Covino, Bernard S. Jr.; Cramer, Stephen D.; Bullard, Sophie J.; Holcomb, Gordon R.; Russell, James H.; Collins, W. Keith; Laylor, Martin H.; Cryer, Curtis B.

    2002-03-01

    Operation of thermal spray zinc (Zn) anodes for cathodic protection (CP) of reinforced concrete structures was investigated in laboratory and field studies conducted by the Albany Research Center (ARC) in collaboration with the Oregon Department of Transportation. The purposes of the research presented in this report were: evaluate the need for preheating concrete to improve the adhesion of the anode; estimate the service life of thermal spray Zn CP anodes; determine the optimum thickness for Zn CP anodes; characterize the anode-concrete interfacial chemistry; and correlate field and laboratory results. Laboratory studies involved accelerated electrochemical aging of thermal sprayed Zn anodes on concrete slabs, some of which were periodically wetted while others were unwetted. Concrete used in the slabs contained either 1.2 or 3 kg NaCl /m3 (2 or 5 lbs NaCl /yd3) as part of the concrete mix design. The Zn anodes were applied to the slabs using the twin wire arc-spray technique. Half of the slabs were preheated to 120-160 C (250-320 F) to improve the initial Zn anode bond strength and the other half were not. Accelerated aging was done at a current density of 0.032 A/m2 (3 mA/ft2), 15 times that used on Oregon DOT Coastal bridges, i.e, . 0.0022 A/m2 (0.2 mA/ft2) Cores from the Cape Creek Bridge (OR), the Richmond San Rafael Bridge (CA), and the East Camino Underpass (CA) were used to study the anode-concrete interfacial chemistry, to relate the chemistry to electrochemical age at the time of sampling, and to compare the chemistry of the field anodes to the chemistry of anodes from the laboratory studies. Cores from a CALTRANS study of a silane sealant used prior to the application of the Zn anodes and cores with galvanized rebar from the Longbird Bridge (Bermuda) were also studied. Aged laboratory and field anodes were characterized by measuring some or all of the following parameters: thickness, bond strength, anode-concrete interfacial chemistry, bulk chemistry

  14. Simultaneously Harvesting Thermal and Mechanical Energies based on Flexible Hybrid Nanogenerator for Self-Powered Cathodic Protection.

    PubMed

    Zhang, Hulin; Zhang, Shangjie; Yao, Guang; Huang, Zhenlong; Xie, Yuhang; Su, Yuanjie; Yang, Weiqing; Zheng, Chunhua; Lin, Yuan

    2015-12-30

    Metal corrosion occurs anytime and anywhere in nature and the corrosion prevention has a great significance everywhere in national economic development and daily life. Here, we demonstrate a flexible hybrid nanogenerator (NG) that is capable of simultaneously or individually harvesting ambient thermal and mechanical energies and used for a self-powered cathodic protection (CP) system without using an external power source. Because of its double peculiarities of both pyroelectric and piezoelectric properties, a polarized poly(vinylidene fluoride) (PVDF) film-based NG was constructed to scavenge both thermal and mechanical energies. As a supplementary, a triboelectric NG was constructed below the pyro/piezoelectric NG to grab ambient mechanical energy. The output power of the fabricated hybrid NG can be directly used to protect the metal surface from the chemical corrosion. Our results not only verify the feasibility of self-powered CP-based NGs, but also expand potential self-powered applications.

  15. Gene expression by the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough grown on an iron electrode under cathodic protection conditions.

    PubMed

    Caffrey, Sean M; Park, Hyung Soo; Been, Jenny; Gordon, Paul; Sensen, Christoph W; Voordouw, Gerrit

    2008-04-01

    The genome sequence of the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough was reanalyzed to design unique 70-mer oligonucleotide probes against 2,824 probable protein-coding regions. These included three genes not previously annotated, including one that encodes a c-type cytochrome. Using microarrays printed with these 70-mer probes, we analyzed the gene expression profile of wild-type D. vulgaris grown on cathodic hydrogen, generated at an iron electrode surface with an imposed negative potential of -1.1 V (cathodic protection conditions). The gene expression profile of cells grown on cathodic hydrogen was compared to that of cells grown with gaseous hydrogen bubbling through the culture. Relative to the latter, the electrode-grown cells overexpressed two hydrogenases, the hyn-1 genes for [NiFe] hydrogenase 1 and the hyd genes, encoding [Fe] hydrogenase. The hmc genes for the high-molecular-weight cytochrome complex, which allows electron flow from the hydrogenases across the cytoplasmic membrane, were also overexpressed. In contrast, cells grown on gaseous hydrogen overexpressed the hys genes for [NiFeSe] hydrogenase. Cells growing on the electrode also overexpressed genes encoding proteins which promote biofilm formation. Although the gene expression profiles for these two modes of growth were distinct, they were more closely related to each other than to that for cells grown in a lactate- and sulfate-containing medium. Electrochemically measured corrosion rates were lower for iron electrodes covered with hyn-1, hyd, and hmc mutant biofilms than for wild-type biofilms. This confirms the importance, suggested by the gene expression studies, of the corresponding gene products in D. vulgaris-mediated iron corrosion.

  16. Mechanical and chemical protection of a wired enzyme oxygen cathode by a cubic phase lyotropic liquid crystal.

    PubMed

    Rowinski, Pawel; Kang, Chan; Shin, Hyosul; Heller, Adam

    2007-02-01

    When implanted in animals, enzyme-containing battery electrodes, biofuel cell electrodes, and biosensors are often damaged by components of the biological environment. An O2 cathode, superior to the classical platinum cathode, which would be implanted, as part of a caseless physiological pH miniature Zn-O2 battery or as part of a caseless and membraneless miniature glucose-O2 biofuel cell, is rapidly damaged by serum urate at its operating potential. The cathode is made by electrically connecting, or wiring, reaction centers of bilirubin oxidase to carbon with an electron-conducting redox hydrogel. In the physiological pH 7.3 electrolyte battery or biofuel cell, the O2 cathode should operate at, or positive of, 0.3 V (Ag/AgCl), where the urate anion, a common serum component, is electrooxidized. Because an unidentified urate electrooxidation intermediate, formed in the presence of O2, damages the wired bilirubin oxidase electrocatalyst, urate must be excluded from the cathode. Unlike O2, which permeates through both the lipid and the aqueous interconnected networks of cubic-phase lyotropic liquid crystals, urate permeates only through their continuous three-dimensional aqueous channel networks. The aqueous channels have well-defined diameters of approximately 5 nm in the monoolein/water cubic-phase liquid crystal. Through tailoring the wall charge of the aqueous channels, the anion/cation permeability ratio can be modulated. Thus, doping the monoolein of the monoolein/water liquid crystal with 1,2-dioleoyl-sn-glycero-3-phosphate makes the aqueous channel walls anionic and reduces the urate permeation in the liquid crystal. As a result, the ratio of the urate electrooxidation current to the O2 electroreduction current is reduced from 1:3 to 1:100 for 5-mm O2 cathodes rotating at 1000 rpm. Doping with 1,2-dioleoyl-sn-glycero-3-phosphate also increases the shear strength of the cubic-phase monoolein/water lyotropic liquid crystal. While the undoped liquid crystal is

  17. Efficient salt removal in a continuously operated upflow microbial desalination cell with an air cathode.

    PubMed

    Jacobson, Kyle S; Drew, David M; He, Zhen

    2011-01-01

    Microbial desalination cells (MDCs) hold great promise for drinking water production because of potential energy savings during the desalination process. In this study, we developed a continuously operated MDC--upflow microbial desalination cell (UMDC) for the purpose of salt removal. During the 4-month operation, the UMDC constantly removed salts and generated bio-electricity. At a hydraulic retention time (HRT) of 4 days (salt solution) and current production of ∼62 mA, the UMDC was able to remove more than 99% of NaCl from the salt solution that had an initial salt concentration of 30 g total dissolved solids (TDS)/L. In addition, the TDS removal rate was 7.50 g TDSL(-1)d(-1) (salt solution volume) or 5.25 g TDSL(-1)d(-1) (wastewater volume), and the desalinated water met the drinking water standard, in terms of TDS concentration. A high charge transfer efficiency of 98.6% or 81% was achieved at HRT 1 or 4d. The UMDC produced a maximum power density of 30.8 W/m(3). The phenomena of bipolar electrodialysis and proton transport in the UMDC were discussed. These results demonstrated the potential of the UMDC as either a sole desalination process or a pre-desalination reactor for downstream desalination processes. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Protective coating for MCFC cathode: Low temperature potentiostatic deposition of CoOOH on nickel in aqueous media containing glycine

    NASA Astrophysics Data System (ADS)

    Mansour, C.; Pauporté, T.; Ringuedé, A.; Albin, V.; Cassir, M.

    The corrosion and dissolution of the state-of-the-art nickel cathode is one of the major problems for the development of the molten carbonate fuel cell. In order to protect this cathode, electrochemical potentiostatic deposition, a cheap and low-temperature technique, was used to produce CoOOH coating. It is well known that the lithiated cobalt oxide (LiCoO 2, stable from produced at 650 °C in molten carbonates) is significantly less soluble than nickel oxide. Potential-acidity diagrams of the cobalt-water system with the presence of a complexing agent, glycine, established from a new critical data set, allowed to predict the thermodynamic stability of CoOOH in a range of 25-80 °C. The deposition process was optimised on dense nickel substrates, analysing thoroughly the effect of the temperature, imposed potential, pH, electrolysis duration and the role of glycine. The structure and morphology of the thin layers prepared were characterised by X-ray diffraction and scanning electron microscopy (SEM). XRD measurements showed the presence of the characteristic CoOOH lines in varied experimental conditions. The CoOOH coatings were spontaneously transformed into LiCoO 2 in the molten carbonate melt. Preliminary results, obtained from ex situ and in situ techniques, on their behaviour and stability in MCFC conditions are given here.

  19. A Study on Effects of Mechanical Stress and Cathodic Protection on Marine Coatings on Mild Steel in Artificial Seawater

    NASA Astrophysics Data System (ADS)

    Yang, Hong-Qi; Zhang, Qi; Tu, San-Shan; Li, Yi-Min; Wang, You; Huang, Yi

    2016-09-01

    In this work, the separate and combined effects of elastic stress and cathodic protection (CP) potential on barrier properties of two marine coating systems applied on Q235 steel plates in artificial seawater were investigated through measurements of electrochemical impedance spectra. The obtained results indicated that elastic stress could have a significant influence on coating barrier property, and the extent of this influence depends on both the magnitude and direction of elastic stress. Meanwhile, it was shown that the separate application of CP could also promote coating degradation, and for both coating systems, the more negative the applied CP potential, the more quickly and more seriously the coatings deteriorated. Furthermore, compared with the sample with only stress or CP, the results showed that the interaction between mechanical stress and CP could reduce their respective impact on coating barrier property, and the combined effect depends on the predominant factor.

  20. Cathodic protection of pre-tensioned concrete. Part 1: Brittle fracture propensity of corrosion damaged prestressing tendon wire

    SciTech Connect

    Stauder, A.L.; Hartt, W.H.

    1998-12-31

    Constant extension rate tests were performed upon prestressing wire specimens in air and in saturated Ca(OH), solution at {minus}0.90 and {minus}1.30 v (SCE) in order to investigate the influence of various levels of precorrosion upon mechanical properties and fracture behavior. It was determined that ultimate tensile strength (UTS) was reduced to a greater extent in the case of specimens which exhibited layer corrosion compared to those with simulated pits. The UTS of layer corroded specimens was not significantly influenced by corrosion morphology acuity but, instead, correlated with the magnitude of cross sectional area reduction. The results are discussed within the context of the previously proposed negative potential limit of {minus}0.90 v (SCE) for cathodic protection of prestressing steel, and a modified qualification criterion is introduced based upon a relationship between fracture load (alternatively, prestress level) and the magnitude of cross section reduction by corrosion.

  1. Study of chloride ion migration in reinforced concrete under cathodic protection. Final report

    SciTech Connect

    Orlova, N.V.; Westall, J.C.; Rehani, M.; Koretsky, M.D.

    1999-09-01

    The migration of chloride ions in concrete with steel reinforcement was investigated. Mortar blocks (15 cm x 15 cm x 17 cm) of various composition (water to cement ratio, chloride ion content) were cast with an iron mesh cathode imbedded along one face and a thermally sprayed zinc anode applied to the opposite face. Current densities of 0.033 and 0.066 A (sq m) were applied to the blocks over a period of one year at constant temperature and humidity. The zinc face was covered with a pond of saturated calcium hydroxide to prevent polarization of the zinc-concrete interface. Over the course of polarization, potential vs. time curves were recorded and samples of mortar were extracted for determination of chloride concentration.

  2. Continuous calibration of a vacuum ultraviolet system from 65 to 125 nm by a cascade arc and comparison with the calibrated line radiation of a hollow cathode.

    PubMed

    Frost, R M; Awakowicz, P

    1997-03-20

    A high-power stationary helium cascade arc has been developed as a standard source for continuum radiation in the VUV spectral range from 65 to 125 nm. The calibration of the VUV system response was based on the calculated and measured continuum radiation of a 2-mmphi pure He arc. Diagnostics of the arc plasma in partial thermal equilibrium yielded the electron density and the temperature that were inserted in the calculations of the continuous radiation. The results were compared with the helium, argon, and krypton radiation lines of a high-current hollow cathode lamp. This lamp was built according to the construction drawings of a hollow cathode, which was calibrated by means of the electron synchrotron radiation at the Physikalisch Technische Bundesanstalt Berlin.

  3. Core-Protected Platinum Monolayer Shell High-Stability Electrocatalysts for Fuel-Cell Cathodes

    SciTech Connect

    K Sasaki; H Naohara; Y Cai; Y Choi; P Liu; M Vukmirovic; J Wang; R Adzic

    2011-12-31

    Platinum monolayers can act as shells for palladium nanoparticles to lead to electrocatalysts with high activities and an ultralow platinum content, but high platinum utilization. The stability derives from the core protecting the shell from dissolution. In fuel-cell tests, no loss of platinum was observed in 200,000 potential cycles, whereas loss of palladium was significant.

  4. Core-Protected Platinum Monolayer Shell High-Stability Electrocatalysts for Fuel-Cell Cathodes

    SciTech Connect

    Adzic, R.R.; Sasaki, K.; Naohara, H.; Cai, Y.; Choi, Y.M.; Liu, P.; Vukmirovic, M.B.; Wang, J.X.

    2010-11-08

    More than skin deep: Platinum monolayers can act as shells for palladium nanoparticles to lead to electrocatalysts with high activities and an ultralow platinum content, but high platinum utilization. The stability derives from the core protecting the shell from dissolution. In fuel-cell tests, no loss of platinum was observed in 200?000 potential cycles, whereas loss of palladium was significant.

  5. Corrosion protection of Arctic offshore structures: Final report. [Effects of temperature and salinity on required cathodic protection current

    SciTech Connect

    Sackinger, W.M.; Rogers, J.C.; Feyk, C.; Theuveny, B.

    1985-10-01

    Results are presented for a research program on corrosion prevention for Arctic offshore structures which are in contact with sea ice for a significant portion of the year. The electrical method most adaptable for structure protection involves the injection of impressed current from several remote anodes buried just beneath the sea floor. The electrical resistivity of annual sea ice as a function of temperature and salinity is presented. Details of the interface layers formed between sea ice and steel in the presence of current injection are shown. A computer program was developed to enable the calculation of protective current density into the structure, in the presence of ice rubble and ridges around the structure. The program and the results of an example calculation are given for a caisson- retained island structure. 81 refs., 103 figs., 3 tabs.

  6. Low-temperature liquid phase deposited TiO 2 films on stainless steel for photogenerated cathodic protection applications

    NASA Astrophysics Data System (ADS)

    Lei, C. X.; Zhou, H.; Feng, Z. D.; Zhu, Y. F.; Du, R. G.

    2011-06-01

    The low-temperature synthesis of anatase TiO 2 films was an imperative requirement for their application to corrosion prevention of metals. In this paper, a liquid phase deposition (LPD) technique was developed to prepare TiO 2 films on SUS304 stainless steel (304SS) at a relatively low temperature (80 °C). The as-prepared films were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photon spectroscopy (XPS). It was observed that a dense and crack-free anatase TiO 2 film with a thickness about 300 nm was obtained. The film contained some fluorine and nitrogen elements, and the amounts of these impurities were greatly decreased upon calcination. Under the white light illumination, the electrode potential of TiO 2 coated 304SS rapidly shifted to a more negative direction. Moreover, the photopotential of TiO 2/304SS electrode showed more negative values with increased film thickness. In conclusion, the photogenerated cathodic protection of 304SS was achieved by the low-temperature LPD-derived TiO 2 film.

  7. 42 CFR 3.208 - Continued protection of patient safety work product.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Continued protection of patient safety work product... GENERAL PROVISIONS PATIENT SAFETY ORGANIZATIONS AND PATIENT SAFETY WORK PRODUCT Confidentiality and Privilege Protections of Patient Safety Work Product § 3.208 Continued protection of patient safety...

  8. Cathodic protection system for underground M.S. pipeline of watersupply project.

    PubMed

    Patil, V D; Phulari, P S

    2003-01-01

    Corrosion of steel embedded in soil can generally be explained in terms of long cell action arising from differential aeration. The significant factors to promote corrosion are soil potential, Resistivity and draining characteristics. As the corrosive nature of soil is not fixed absolute value, the said study can be analyzed by adopting the following methodology. i) Study of state of soil at different location. ii) Nature of corrosion under consideration With above methodology an attempt can be made to achieve the following objective to, i) Assess the extent of corrosive tendencies of soil along the pipeline. ii) Co-relate potential and resistivity with corrosive parameters of soil and, iii) Suggest the appropriate remedial means for protecting it from corrosion. i.e. Galvanic activity.

  9. A new approach to the determination of the cathodic protection period in zinc-rich paints

    SciTech Connect

    Abreu, C.M.; Izquierdo, M.; Merino, P.; Novoa, X.R.; Perez, C.

    1999-12-01

    The present study examined the behavior of zinc-rich paints (ZRP) based on an epoxy binder in 3% sodium chloride (NaCl) solution. The study focused on the effect of some design parameters often considered in paint formulation. The paint thickness, the zinc particle grain size, and the zinc particle distribution in the paint were studied. The study was based mainly on electrochemical impedance spectroscopy (EIS). EIS results were interpreted using a model involving the contact impedance between zinc particles. The contact impedance and electrolyte resistance throughout the coating defined the protective action of ZRP. Based on these two concepts, a practical approach to evaluate ZRP performance was given. This approach, called total film resistance (TFR), can be used for optimization criteria in paint formulation.

  10. Controlled assembly of layer-by-layer stacking continuous graphene oxide films and their application for actively modulated field electron emission cathodes.

    PubMed

    Huang, Yuan; She, Juncong; Yang, Wenjie; Deng, Shaozhi; Xu, Ningsheng

    2014-04-21

    A featured "vapor transportation" assembly technique was developed to attain layer-by-layer stacking continuous graphene oxide (GO) films on both flat and concavo-concave surfaces. Few-layer (layer number < 10) GO sheets were "evaporated" (carried by water vapor) from the water-dispersed GO suspension and smoothly/uniformly tiled on the substrate surface. We have found evidence of the influence of the deposition time and substrate-liquid separation on the film thickness. A model was proposed for interpreting the assembly process. It was found that a current conditioning would induce a reduction of the GO surface and form an Ohmic contact between the GO-metal interfaces. Accordingly, an actively modulated GO cold cathode was fabricated by locally depositing continuous GO sheets on the drain electrode of a metal-oxide-semiconductor field effect transistor (MOSFET). The field emission current of the GO cathode can be precisely controlled by the MOSFET gate voltage (VGS). A current modulation range from 1 × 10(-10) A to 6.9 × 10(-6) A (4 orders of magnitude) was achieved by tuning the VGS from 0.812 V to 1.728 V. Due to the self-acting positive feedback of the MOSFET, the emission current fluctuation was dramatically reduced from 57.4% (non-control) to 3.4% (controlled). Furthermore, the integrated GO cathode was employed for a lab-prototype display pixel application demonstrating the active modulation of the phosphor luminance, i.e. from 0.01 cd m(-2) to 34.18 cd m(-2).

  11. Controlled assembly of layer-by-layer stacking continuous graphene oxide films and their application for actively modulated field electron emission cathodes

    NASA Astrophysics Data System (ADS)

    Huang, Yuan; She, Juncong; Yang, Wenjie; Deng, Shaozhi; Xu, Ningsheng

    2014-03-01

    A featured ``vapor transportation'' assembly technique was developed to attain layer-by-layer stacking continuous graphene oxide (GO) films on both flat and concavo-concave surfaces. Few-layer (layer number < 10) GO sheets were ``evaporated'' (carried by water vapor) from the water-dispersed GO suspension and smoothly/uniformly tiled on the substrate surface. We have found evidence of the influence of the deposition time and substrate-liquid separation on the film thickness. A model was proposed for interpreting the assembly process. It was found that a current conditioning would induce a reduction of the GO surface and form an Ohmic contact between the GO-metal interfaces. Accordingly, an actively modulated GO cold cathode was fabricated by locally depositing continuous GO sheets on the drain electrode of a metal-oxide-semiconductor field effect transistor (MOSFET). The field emission current of the GO cathode can be precisely controlled by the MOSFET gate voltage (VGS). A current modulation range from 1 × 10-10 A to 6.9 × 10-6 A (4 orders of magnitude) was achieved by tuning the VGS from 0.812 V to 1.728 V. Due to the self-acting positive feedback of the MOSFET, the emission current fluctuation was dramatically reduced from 57.4% (non-control) to 3.4% (controlled). Furthermore, the integrated GO cathode was employed for a lab-prototype display pixel application demonstrating the active modulation of the phosphor luminance, i.e. from 0.01 cd m-2 to 34.18 cd m-2.

  12. Hydrogen hollow cathode ion source

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J., Jr.; Sovey, J. S.; Roman, R. F. (Inventor)

    1980-01-01

    A source of hydrogen ions is disclosed and includes a chamber having at one end a cathode which provides electrons and through which hydrogen gas flows into the chamber. Screen and accelerator grids are provided at the other end of the chamber. A baffle plate is disposed between the cathode and the grids and a cylindrical baffle is disposed coaxially with the cathode at the one end of the chamber. The cylindrical baffle is of greater diameter than the baffle plate to provide discharge impedance and also to protect the cathode from ion flux. An anode electrode draws the electrons away from the cathode. The hollow cathode includes a tubular insert of tungsten impregnated with a low work function material to provide ample electrons. A heater is provided around the hollow cathode to initiate electron emission from the low work function material.

  13. Highly CO2-Tolerant Cathode for Intermediate-Temperature Solid Oxide Fuel Cells: Samarium-Doped Ceria-Protected SrCo0.85Ta0.15O3-δ Hybrid.

    PubMed

    Li, Mengran; Zhou, Wei; Zhu, Zhonghua

    2017-01-25

    Susceptibility to CO2 is one of the major challenges for the long-term stability of the alkaline-earth-containing cathodes for intermediate-temperature solid oxide fuel cells. To alleviate the adverse effects from CO2, we incorporated samarium-stabilized ceria (SDC) into a SrCo0.85Ta0.15O3-δ (SCT15) cathode by either mechanical mixing or a wet impregnation method and evaluated their cathode performance stability in the presence of a gas mixture of 10% CO2, 21% O2, and 69% N2. We observed that the CO2 tolerance of the hybrid cathode outperforms the pure SCT15 cathode by over 5 times at 550 °C. This significant enhancement is likely attributable to the low CO2 adsorption and reactivity of the SDC protective layer, which are demonstrated through thermogravimetric analysis, energy-dispersive spectroscopy, and electrical conductivity study.

  14. Continuing dental education in radiation protection: monitoring the outcomes.

    PubMed

    Absi, Eg; Drage, Na; Thomas, Hs; Newcombe, Rg; Nash, Es

    2009-03-01

    To evaluate an evolving radiation protection dental postgraduate course run in Wales between 2003 and 2007. We compared three standardized course series. Course content was enhanced in 2006 to target areas of weakness. In 2007, a single best answer multiple choice questionnaire instrument superseded a true/false format. Practitioners' performance was studied pre- and immediately post-training. 900 participants completed identical pre- and post-course validated multiple choice questionnaires. 809 (90%) paired morning-afternoon records, including those of 52 dental care professionals (DCPs), were analysed. Mean (standard error) pre- and post-course percentage scores for the three courses were 33.8 (0.9), 35.4 (1.4), 34.6 (1.0) and 63.6 (0.9), 59.0 (1.4), 69.5 (0.9). Pre-training, only 2.4%, 3.1% and 4.9% of participants achieved the pass mark compared to 57.7%, 48.4% and 65.9% post-training, indicating a rather greater pass rate and gain in the most recent series than earlier ones. In recent series, older more experienced candidates scored slightly higher; however, their gain from pre- to post-training was slightly less. Baseline levels of radiation protection knowledge remained very low but attending an approved course improved this considerably. Targeting areas of weaknesses produced higher scores. Current radiation protection courses may not be optimal for DCPs.

  15. Hierarchical Porous Nickel Cobaltate Nanoneedle Arrays as Flexible Carbon-Protected Cathodes for High-Performance Lithium-Oxygen Batteries.

    PubMed

    Xue, Hairong; Wu, Shichao; Tang, Jing; Gong, Hao; He, Ping; He, Jianping; Zhou, Haoshen

    2016-04-06

    Rechargeable lithium-oxygen (Li-O2) batteries are consequently considered to be an attractive energy storage technology because of the high theoretical energy densities. Here, an effective binder-free cathode with high capacity for Li-O2 batteries, needle-like mesoporous NiCo2O4 nanowire arrays uniformly coated on the flexible carbon textile have been in situ fabricated via a facile hydrothermal process followed by low temperature calcination. Because of the material and structural features, the needle-like NiCo2O4 nanowire arrays (NCONWAs) served as a binder-free cathode exhibits high specific capacity (4221 mAh g(-1)), excellent rate capability, and outstanding cycling stability (200 cycles). This cathode based on nonprecious mesoporous metal oxides nanowire arrays has large open spaces and high surface area, providing numerous catalytically active sites and effective transmission pathways for lithium ion and oxygen, and promises the abundant Li2O2 storage. The fast electron transport by directly anchoring on the substrate ensures fast electrochemical reaction process involved with the every nanowire. Furthermore, a bendable Li-O2 battery assembled by using the flexible NCONWAs as the cathode, can be able to light an LED and shows good rate capability and cyclic stability.

  16. Mechanisms of LiCoO2 Cathode Degradation by Reaction with HF and Protection by Thin Oxide Coatings.

    PubMed

    Tebbe, Jonathon L; Holder, Aaron M; Musgrave, Charles B

    2015-11-04

    Reactions of HF with uncoated and Al and Zn oxide-coated surfaces of LiCoO2 cathodes were studied using density functional theory. Cathode degradation caused by reaction of HF with the hydroxylated (101̅4) LiCoO2 surface is dominated by formation of H2O and a LiF precipitate via a barrierless reaction that is exothermic by 1.53 eV. We present a detailed mechanism where HF reacts at the alumina coating to create a partially fluorinated alumina surface rather than forming AlF3 and H2O and thus alumina films reduce cathode degradation by scavenging HF and avoiding H2O formation. In contrast, we find that HF etches monolayer zinc oxide coatings, which thus fail to prevent capacity fading. However, thicker zinc oxide films mitigate capacity loss by reacting with HF to form a partially fluorinated zinc oxide surface. Metal oxide coatings that react with HF to form hydroxyl groups over H2O, like the alumina monolayer, will significantly reduce cathode degradation.

  17. The use of non-invasive procedures described in ASTM ES40-94 for evaluating the suitability of an UST for upgrading with cathodic protection

    SciTech Connect

    Rogers, W.F.

    1995-12-31

    This paper outlines field procedures and data analysis requirements for the use of non-invasive procedures to evaluate the suitability of tanks for upgrading with cathodic protection. The non-invasive evaluation procedure is one of the three alternative means of assessing USTs, and there are specific procedures described for each of the assessment procedures which are detailed in ES40-94. The UST owner/operator and corrosion engineer should recognize that there are accept/reject guidelines in the standard, and that many existing underground storage tanks will not be found suitable for upgrading.

  18. Continuous wavelet transform based time-scale and multifractal analysis of the nonlinear oscillations in a hollow cathode glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Nurujjaman, Md.; Narayanan, Ramesh; Iyengar, A. N. Sekar

    2009-10-01

    Continuous wavelet transform (CWT) based time-scale and multifractal analyses have been carried out on the anode glow related nonlinear floating potential fluctuations in a hollow cathode glow discharge plasma. CWT has been used to obtain the contour and ridge plots. Scale shift (or inversely frequency shift), which is a typical nonlinear behavior, has been detected from the undulating contours. From the ridge plots, we have identified the presence of nonlinearity and degree of chaoticity. Using the wavelet transform modulus maxima technique we have obtained the multifractal spectrum for the fluctuations at different discharge voltages and the spectrum was observed to become a monofractal for periodic signals. These multifractal spectra were also used to estimate different quantities such as the correlation and fractal dimension, degree of multifractality, and complexity parameters. These estimations have been found to be consistent with the nonlinear time series analysis.

  19. Design of surface protective layer of LiF/FeF 3 nanoparticles in Li-rich cathode for high-capacity Li-ion batteries

    SciTech Connect

    Zhao, Taolin; Li, Li; Chen, Renjie; Wu, Huiming; Zhang, Xiaoxiao; Chen, Shi; Xie, Man; Wu, Feng; Lu, Jun; Amine, Khalil

    2015-01-01

    Advanced lithium-ion batteries for renewable energy storage applications have become a major research interest in recent years. Much better performance can be realized by improvements in the material surface design, especially for the cathode materials. Here, we present a new design for a surface protective layer formed via a facile aqueous solution process in which a nano-architectured layer of LiF/FeF3 is epitaxially grown on bulk hierarchical Li-rich cathode Li[Li0.2Ni0.2Mn0.6]O2. Coin cell tests of this material in the voltage range of 2–4.8 V indicated a high reversible capacity (260.1 mA h g-1 at 0.1 C), superior rate performance (129.9 mA h g-1 at 20 C), and excellent capacity retention. Differential scanning calorimetry showed good thermal stability. The enhanced capacity and cycling stability are attributed to the suppression of interfacial side reactions as well as the conversion reaction resulting from the introduction of LiF/FeF3 as a surface protective layer.

  20. A-e Services to perform a cathodic protection survey of the bulk fuel terminals at N. S. C. Pearl Harbor, Hawaii. Volume II

    SciTech Connect

    Not Available

    1982-06-01

    This section includes one 25,000 bbl, two 80,000 bbl, and two 150,000 bbl tanks in the Pearl City Tank Farm. Tanks in the upper tank farm consist of six 150,000 bbl tanks, eight underground diesel storage tanks at building 60, four 10,000 bbl underground surge tanks, two ballast tanks, two diesel tanks, one hot settling tank and one diesel flotation tank. Four 50,000 bbl tanks and one 80,000 bbl tank at the middle tank farm are included along with four 50,000 bbl tanks at the lower tank farm. One outdoor ballast tank and one water storage tank at the Stilling Basin and associated piping are also included. The existing impressed current type of cathodic protection system and the existing sacrificial type of cathodic protection system are considered and three POL lines located in the lower Red Hill Tunnel from the Red Hill storage tanks to the Pearl Harbor Naval Base are included.

  1. Mixed ion/electron-conductive protective soft nanomatter-based conformal surface modification of lithium-ion battery cathode materials

    NASA Astrophysics Data System (ADS)

    Park, Jang-Hoon; Kim, Ju-Myung; Lee, Chang Kee; Lee, Sang-Young

    2014-10-01

    Understanding and control of interfacial phenomena between electrode material and liquid electrolytes are of major scientific importance for boosting development of high-performance lithium ion batteries with reliable electrochemical/safety attributes. Here, as an innovative surface engineering approach to address the interfacial issues, a new concept of mixed ion/electron-conductive soft nanomatter-based conformal surface modification of the cathode material is presented. The soft nanomatter is comprised of an electron conductive carbonaceous (C) substance embedded in an ion conductive polyimide (PI) nanothin compliant film. In addition to its structural uniqueness, the newly proposed surface modification benefits from a simple fabrication process. The PI/carbon soft nanomatter is directly synthesized on LiCoO2 surface via one-pot thermal treatment of polyamic acid (=PI precursor) and sucrose (=carbon source) mixture, where the LiCoO2 powders are chosen as a model system to explore the feasibility of this surface engineering strategy. The resulting PI/carbon coating layer facilitates electronic conduction and also suppresses unwanted side reactions arising from the cathode material-liquid electrolyte interface. These synergistic coating effects of the multifunctional PI/carbon soft nanomatter significantly improve high-voltage cell performance and also mitigate interfacial exothermic reaction between cathode material and liquid electrolyte.

  2. Arcjet Cathode Phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  3. Arcjet cathode phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  4. Gene Expression by the Sulfate-Reducing Bacterium Desulfovibrio vulgaris Hildenborough Grown on an Iron Electrode under Cathodic Protection Conditions▿ †

    PubMed Central

    Caffrey, Sean M.; Park, Hyung Soo; Been, Jenny; Gordon, Paul; Sensen, Christoph W.; Voordouw, Gerrit

    2008-01-01

    The genome sequence of the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough was reanalyzed to design unique 70-mer oligonucleotide probes against 2,824 probable protein-coding regions. These included three genes not previously annotated, including one that encodes a c-type cytochrome. Using microarrays printed with these 70-mer probes, we analyzed the gene expression profile of wild-type D. vulgaris grown on cathodic hydrogen, generated at an iron electrode surface with an imposed negative potential of −1.1 V (cathodic protection conditions). The gene expression profile of cells grown on cathodic hydrogen was compared to that of cells grown with gaseous hydrogen bubbling through the culture. Relative to the latter, the electrode-grown cells overexpressed two hydrogenases, the hyn-1 genes for [NiFe] hydrogenase 1 and the hyd genes, encoding [Fe] hydrogenase. The hmc genes for the high-molecular-weight cytochrome complex, which allows electron flow from the hydrogenases across the cytoplasmic membrane, were also overexpressed. In contrast, cells grown on gaseous hydrogen overexpressed the hys genes for [NiFeSe] hydrogenase. Cells growing on the electrode also overexpressed genes encoding proteins which promote biofilm formation. Although the gene expression profiles for these two modes of growth were distinct, they were more closely related to each other than to that for cells grown in a lactate- and sulfate-containing medium. Electrochemically measured corrosion rates were lower for iron electrodes covered with hyn-1, hyd, and hmc mutant biofilms than for wild-type biofilms. This confirms the importance, suggested by the gene expression studies, of the corresponding gene products in D. vulgaris-mediated iron corrosion. PMID:18310429

  5. Vacuum ultra-violet emission of plasma discharges with high Xe partial pressure using a cathode protective layer with high secondary electron emission

    SciTech Connect

    Zhu, Di; Song, Le; Zhang, Xiong; Kajiyama, Hiroshi

    2014-02-14

    In this work, the mechanism of the vacuum ultra-violet (VUV) emission of plasma discharges, with high Xe partial pressure and high ion-induced secondary electrons emission protective layer, is studied by measuring the VUV light emission directly and comparing it with two-dimensional simulations. From the panel measurement, we find that the high intensity of excimer VUV mainly contributes to the high luminous efficacy of SrCaO-plasma display panels (PDP) at a low sustain voltage. The unchanged Xe excitation efficiency indicates that the electron temperature is not decreased by the high secondary electrons emission protective layer, even though the sustain voltage is much lower. From the two-dimensional simulations, we can find that the ratio of excimer VUV to resonant VUV, which is determined by the collision rate in the discharge, is only significantly affected by the Xe partial pressure, while it is independent of the sustain voltage and the secondary-electrons-emission capability of protective layer. The unchanged average electron energy at the moment when the electric field becomes maximum confirms that the improvement of the VUV production efficiency mainly is attributed to the increase in electron heating efficiency of a PDP with high ion-induced secondary electrons emission protective layer. Combining the experimental and the simulation results, we conclude about the mechanism by which the VUV production is improved for the plasma display panel with a high Xe partial pressure and a cold cathode with high ion-induced secondary electrons emission.

  6. Cathodic arcs

    SciTech Connect

    Anders, Andre

    2003-10-29

    Cathodic arc plasma deposition has become the technology of choice for hard, wear and corrosion resistant coatings for a variety of applications. The history, basic physics of cathodic arc operation, the infamous macroparticle problem and common filter solutions, and emerging high-tech applications are briefly reviewed. Cathodic arc plasmas standout due to their high degree of ionization, with important consequences for film nucleation, growth, and efficient utilization of substrate bias. Industrial processes often use cathodic arc plasma in reactive mode. In contrast, the science of arcs has focused on the case of vacuum arcs. Future research directions include closing the knowledge gap for reactive mode, large area coating, linear sources and filters, metal plasma immersion process, with application in high-tech and biomedical fields.

  7. The effect of cerium-based conversion treatment on the cathodic delamination and corrosion protection performance of carbon steel-fusion-bonded epoxy coating systems

    NASA Astrophysics Data System (ADS)

    Ramezanzadeh, B.; Rostami, M.

    2017-01-01

    The effect of surface pre-treatment of pipe surface by green cerium compound and phosphoric acid solution on the fusion-bonded epoxy (FBE) coating performance was studied. The composition and surface morphology of the steel samples treated by acid and Ce solutions were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), equipped with energy dispersive spectroscopy (EDS). Also, the surface free energy was evaluated on these samples through contact angle measurements. In addition, the effect of Ce and acid washing procedures on the adhesion properties and corrosion protection performance of the FBE was examined by pull-off, salt spray and electrochemical impedance spectroscopy (EIS) tests. Results showed that compared to acid washing, the chemical treatment by Ce solution noticeably increased the surface free energy of steel, improved the adhesion properties of FBE, decreased the cathodic delamination rate of FBE, and enhanced the coating corrosion resistance compared to the acid washed samples.

  8. Mechanistic Insight in the Function of Phosphite Additives for Protection of LiNi0.5Co0.2Mn0.3O2 Cathode in High Voltage Li-Ion Cells.

    PubMed

    He, Meinan; Su, Chi-Cheung; Peebles, Cameron; Feng, Zhenxing; Connell, Justin G; Liao, Chen; Wang, Yan; Shkrob, Ilya A; Zhang, Zhengcheng

    2016-05-11

    Triethlylphosphite (TEP) and tris(2,2,2-trifluoroethyl) phosphite (TTFP) have been evaluated as electrolyte additives for high-voltage Li-ion battery cells using a Ni-rich layered cathode material LiNi0.5Co0.2Mn0.3O2 (NCM523) and the conventional carbonate electrolyte. The repeated charge/discharge cycling for cells containing 1 wt % of these additives was performed using an NCM523/graphite full cell operated at the voltage window from 3.0-4.6 V. During the initial charge process, these additives decompose on the cathode surface at a lower oxidation potential than the baseline electrolyte. Impedance spectroscopy and post-test analyses indicate the formation of protective coatings by both additives on the cathode surface that prevent oxidative breakdown of the electrolyte. However, only TTFP containing cells demonstrate the improved capacity retention and Coulombic efficiency. For TEP, the protective coating is also formed, but low Li(+) ion mobility through the interphase layer results in inferior performance. These observations are rationalized through the inhibition of electrocatalytic centers present on the cathode surface and the formation of organophosphate deposits isolating the cathode surface from the electrolyte. The difference between the two phosphites clearly originates in the different properties of the resulting phosphate coatings, which may be in Li(+) ion conductivity through such materials.

  9. Filtered cathodic arc source

    DOEpatents

    Falabella, S.; Sanders, D.M.

    1994-01-18

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge is described. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45[degree] to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles. 3 figures.

  10. Filtered cathodic arc source

    DOEpatents

    Falabella, Steven; Sanders, David M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45.degree. to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  11. Miniature Reservoir Cathode: An Update

    NASA Technical Reports Server (NTRS)

    Vancil, Bernard K.; Wintucky, Edwin G.

    2002-01-01

    We report on recent work to produce a small low power, low cost reservoir cathode capable of long life (more than 100,000 hours) at high loading (> 5 A/sq cm). Our objective is a highly manufacturable, commercial device costing less than $30. Small highly loaded cathodes are needed, especially for millimeter wave tubes, where focusing becomes difficult when area convergence ratios are too high. We currently have 3 models ranging from .060-inch diameter to. 125-inch diameter. Reservoir type barium dispenser cathodes have a demonstrated capability for simultaneous high emission density and long life. Seven reservoir cathodes continue to operate on the cathode life test facility at NSWC, Crane, Indiana at 2 and 4 amps/sq cm. They have accumulated nearly 100,000 hours with practically no change in emission levels or knee temperature.

  12. Understanding the long term effects of cathodic protection on pre-stressed concrete structures: Hydrogen embrittlement of pre-stressing steel

    SciTech Connect

    Enos, D.G.; Williams, A.J. Jr.; Scully, J.R.

    1996-11-01

    This paper addresses the issue of safe cathodic protection limits for pre-stressing steel in concrete given the concern of hydrogen embrittlement (HE). The local environment at the steel/concrete interface was found to vary as a function of vertical position within a laboratory scale marine bridge piling. Embedded pH electrodes indicated that the pH within a steel crevice embedded within a concrete piling decreased from 12.5--7.7 in the atmospheric zone 30.5 cm above the waterline. Hydrogen permeation was detected using embedded sensors at applied potentials (E(app)) as positive as {minus}694 mV{sub SCE} which also confirmed a local pH drop to below 8. In light of this information, a reversible electrode potential (REP)-based safe limit would require knowledge of pH and E(app) as a function of vertical position, as well as an understanding of their influence on HE. To address the latter issue, notched pre-stressing steel tensile specimens were CERT tested at various cathodic polarization levels in (1) saturated Ca(OH){sub 2}, (2) ASTM artificial oceanwater, (3) under a mortar cover in ASTM artificial oceanwater, and (4) a pH 4 environment simulating ferrous ion hydrolysis on corroding pre-stressing steel. CERT results were combined with permeation measurements to determine the relationship between mobile hydrogen concentration (C{sub H}) and fracture initiation stress, {sigma}{sub i}, in each environment over a series of cathodic potentials. A relationship of the form {sigma}{sub i} = {sigma}{sub 0}-{alpha}Log(C{sub H}/C{sub 0}) was observed independent of the environment and pH. The previously reported fixed cracking threshold of {minus}900 mV{sub SCE} in Ca(OH){sub 2} solutions pH adjusted with HCl, irrespective of pH (pH from 7 to 12.5), was explained. Decreasing pH can produce a roughly constant C{sub H} at fixed E(app) due to the opposing influences on hydrogen uptake of increasing overpotential but decreasing availability of a Ca(OH){sub 2} poison.

  13. Manipulation of the immune evasive properties of circulating cathodic antigen induces protective immunity against Schistosomiasis mansoni in C57BL/6 mice.

    PubMed

    Abdeen, Sherif H

    2010-01-01

    Schistosome circulating cathodic antigen (CCA) has been hypothesized to take part in immune evasion mechanisms that protect against host's immunity. To dissect its immunogenicity, lymphoproliferative responses of splenocytes were assessed in C57BL/6 mice immunized with recombinant plasmid constructs expressing full-length and truncated fragments of CCA cDNA, before and after challenge infection with S. mansoni cercariae. Prior to challenge, splenocytes of immunized mice showed low responses to phytohaemagglutinin (PHA) and high responses to native CCA, compared to controls. After challenge, PHA-responses increased on day 3 through day 7 and subsequently declined. On the other hand, CCA-induced responses increased on day 3 post-challenge then declined in mice immunized with CCA fragments lacking the N-terminus (-N CCA). Whereas, mice immunized with full-length or CCA fragment lacking the C-terminus (-C CCA) showed a delayed increase of CCA-induced responses that maximize on day 25. Interestingly, animals immunized with -N CCA showed a significant reduction in worm burden between 42-51%, while, mice immunized with full-length or -C CCA showed lower protection levels of about 15 and 37%, respectively. These findings suggest that CCA may contain immunosuppressive epitopes on the N-terminus. Abrogation of these epitopes could disrupt the immune evasion mechanism orchestrated by CCA, which could aid the development of an alternative vaccination approach.

  14. High current density cathode for electrorefining in molten electrolyte

    DOEpatents

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  15. Protective equipment: continuous and contingent application in the treatment of self-injurious behavior.

    PubMed Central

    Dorsey, M F; Iwata, B A; Reid, D H; Davis, P A

    1982-01-01

    This study evaluated the use of protective equipment in treating self-injurious behavior (SIB) exhibited by three retarded persons. In Experiment 1, the equipment was first applied continuously during 20-min sessions in individual multiple baseline designs across settings. Results showed substantial reductions in head hitting, eye gouging, and hand biting. Brief periods of time-out with the protective equipment were later made contingent on SIB and combined with a differential reinforcement procedure. Reduced levels of SIB was maintained with all subjects. Additionally, the amount of time during which the equipment was applied decreased as the SIB diminished. Experiment 2 evaluated the use of contingent protective equipment (the final condition in Experiment 1) when applied directly in the subjects' living units during the day. During Experiment 2, SIB remained at or below the levels found at the termination of Experiment 1. Finally, in an effort to assess the long-term effectiveness of the procedure, responsibility for implementation was given to the staff who were typically assigned to provide therapy to the subjects. Follow-up probe observations conducted up to 104 days after termination of the final experimental condition showed continued low levels of both SIB and equipment usage. Results of these experiments suggest that contingent protective equipment and differential reinforcement may be effective in reducing chronic self-injury. PMID:7118755

  16. Multiple Hollow Cathode Wear Testing

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    1994-01-01

    A hollow cathode-based plasma contactor has been baselined for use on the Space Station to reduce station charging. The plasma contactor provides a low impedance connection to space plasma via a plasma produced by an arc discharge. The hollow cathode of the plasma contactor is a refractory metal tube, through which xenon gas flows, which has a disk-shaped plate with a centered orifice at the downstream end of the tube. Within the cathode, arc attachment occurs primarily on a Type S low work function insert that is next to the orifice plate. This low work function insert is used to reduce cathode operating temperatures and energy requirements and, therefore, achieve increased efficiency and longevity. The operating characteristics and lifetime capabilities of this hollow cathode, however, are greatly reduced by oxygen bearing contaminants in the xenon gas. Furthermore, an optimized activation process, where the cathode is heated prior to ignition by an external heater to drive contaminants such as oxygen and moisture from the insert absorbed during exposure to ambient air, is necessary both for cathode longevity and a simplified power processor. In order to achieve the two year (approximately 17,500 hours) continuous operating lifetime requirement for the plasma contactor, a test program was initiated at NASA Lewis Research Center to demonstrate the extended lifetime capabilities of the hollow cathode. To date, xenon hollow cathodes have demonstrated extended lifetimes with one test having operated in excess of 8000 hours in an ongoing test utilizing contamination control protocols developed by Sarver-Verhey. The objectives of this study were to verify the transportability of the contamination control protocols developed by Sarver-Verhey and to evaluate cathode contamination control procedures, activation processes, and cathode-to-cathode dispersions in operating characteristics with time. These were accomplished by conducting a 2000 hour wear test of four hollow

  17. Continuous endotracheal tube cuff pressure control system protects against ventilator-associated pneumonia.

    PubMed

    Lorente, Leonardo; Lecuona, María; Jiménez, Alejandro; Lorenzo, Lisset; Roca, Isabel; Cabrera, Judith; Llanos, Celina; Mora, María L

    2014-04-21

    The use of a system for continuous control of endotracheal tube cuff pressure reduced the incidence of ventilator-associated pneumonia (VAP) in one randomized controlled trial (RCT) with 112 patients but not in another RCT with 142 patients. In several guidelines on the prevention of VAP, the use of a system for continuous or intermittent control of endotracheal cuff pressure is not reviewed. The objective of this study was to compare the incidence of VAP in a large sample of patients (n = 284) treated with either continuous or intermittent control of endotracheal tube cuff pressure. We performed a prospective observational study of patients undergoing mechanical ventilation during more than 48 hours in an intensive care unit (ICU) using either continuous or intermittent endotracheal tube cuff pressure control. Multivariate logistic regression analysis (MLRA) and Cox proportional hazard regression analysis were used to predict VAP. The magnitude of the effect was expressed as odds ratio (OR) or hazard ratio (HR), respectively, and 95% confidence interval (CI). We found a lower incidence of VAP with the continuous (n = 150) than with the intermittent (n = 134) pressure control system (22.0% versus 11.2%; p = 0.02). MLRA showed that the continuous pressure control system (OR = 0.45; 95% CI = 0.22-0.89; p = 0.02) and the use of an endotracheal tube incorporating a lumen for subglottic secretion drainage (SSD) (OR = 0.39; 95% CI = 0.19-0.84; p = 0.02) were protective factors against VAP. Cox regression analysis showed that the continuous pressure control system (HR = 0.45; 95% CI = 0.24-0.84; p = 0.01) and the use of an endotracheal tube incorporating a lumen for SSD (HR = 0.29; 95% CI = 0.15-0.56; p < 0.001) were protective factors against VAP. However, the interaction between type of endotracheal cuff pressure control system (continuous or intermittent) and endotracheal tube (with or without SSD) was not

  18. Continuous overturn control of compactors/rollers by rollover protective structures

    PubMed Central

    Myers, Melvin L.

    2009-01-01

    The objective of this article is to report on the effectiveness of Rollover Protective Structures (ROPS) in preventing continuous overturns of compactors/rollers. This study is a case-based analysis of government investigation reports of injury-related overturns of compactors/rollers. The overturns were predominately on construction sites including road and embankment construction in the USA. Other sites included driveway and roadway maintenance or repair and transporting of compactors/rollers either by driving or when loading on or unloading from trailers. The principle intervention observed in controlling a continuous overturn (a roll beyond 90° relative to the impact surface) was the presence of a ROPS on a compactor/roller that serves as an anti-roll bar. The main outcome measures are cases of compactor/roller overturns that are restricted to a 90° roll or are continuous (exceed a 90° roll.) All cases of an overturn in which a ROPS was present resulted in no continuous overturn, and the cases involved with no ROPS averaged an overturn of 301°, showing a propensity for a continuous overturn. This case-based analysis identified a ROPS on compactors/rollers as an effective control for reducing the risk of an overturn to 90° relative to the impact plane. PMID:21765649

  19. Privacy and Security Issues Surrounding the Protection of Data Generated by Continuous Glucose Monitors.

    PubMed

    Britton, Katherine E; Britton-Colonnese, Jennifer D

    2017-03-01

    Being able to track, analyze, and use data from continuous glucose monitors (CGMs) and through platforms and apps that communicate with CGMs helps achieve better outcomes and can advance the understanding of diabetes. The risks to patients' expectation of privacy are great, and their ability to control how their information is collected, stored, and used is virtually nonexistent. Patients' physical security is also at risk if adequate cybersecurity measures are not taken. Currently, data privacy and security protections are not robust enough to address the privacy and security risks and stymies the current and future benefits of CGM and the platforms and apps that communicate with them.

  20. Lipon coatings for high voltage and high temperature Li-ion battery cathodes

    DOEpatents

    Dudney, Nancy J.; Liang, Chengdu; Nanda, Jagjit; Veith, Gabriel M.; Kim, Yoongu; Martha, Surendra Kumar

    2017-02-14

    A lithium ion battery includes an anode and a cathode. The cathode includes a lithium, manganese, nickel, and oxygen containing compound. An electrolyte is disposed between the anode and the cathode. A protective layer is deposited between the cathode and the electrolyte. The protective layer includes pure lithium phosphorus oxynitride and variations that include metal dopants such as Fe, Ti, Ni, V, Cr, Cu, and Co. A method for making a cathode and a method for operating a battery are also disclosed.

  1. Model for designing planar magnetron cathodes

    SciTech Connect

    Garcia, M.

    1997-09-30

    This report outlines an analytical model of the distribution of plasma in the cathode fall of a planar magnetron cathode. Here I continue commentary on previous work, and introduce an ion sheath model to describe the discharge dark space below the magnetron halo.

  2. Elastomeric Cathode Binder

    NASA Technical Reports Server (NTRS)

    Yen, S. P. S.; Shen, D. S.; Somoano, R. B.

    1985-01-01

    Soluble copolymer binder mixed with cathode material and solvent forms flexible porous cathode used in lithium and Ni/Cd batteries. Cathodes prepared by this process have lower density due to expanding rubbery binder and greater flexibility than conventional cathodes. Fabrication procedure readily adaptable to scaled-up processes.

  3. Hollow cathode apparatus

    NASA Technical Reports Server (NTRS)

    Aston, G. (Inventor)

    1984-01-01

    A hollow cathode apparatus is described, which can be rapidly and reliably started. An ignitor positioned upstream from the hollow cathode, generates a puff of plasma that flows with the primary gas to be ionized through the cathode. The plasma puff creates a high voltage breakdown between the downstream end of the cathode and a keeper electrode, to heat the cathode to an electron-emitting temperature.

  4. A cathode material based on the iron fluoride with an ultra-thin Li3FeF6 protective layer for high-capacity Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Juan; Xu, Zhanglin; Zhou, Haochen; Tang, Jingjing; Sun, Hongxu; Ding, Jing; Zhou, Xiangyang

    2017-09-01

    Iron fluoride based on the multi-electron reaction is a typical representative among the new-style cathode materials for Lithium-ion batteries, which is attracting extensive attentions. To relieve the cathode dissolution and interfacial side reactions and improve the electrochemical performance of FeF3·0.33H2O, we design an ultra-thin Li3FeF6 protective layer, which is in-situ formed on the surface of FeF3·3H2O particles by a facile process. The prepared Li3FeF6/FeF3·0.33H2O (LF50) composite displays a superior rate performance (152 mAh g-1 at 1000 mA g-1), which is remarkable to many other carbon-free iron fluorides. And it is noticeable that a reversible capacity of 174 mAh g-1 can be retained after 100 cycles, indicating an outstanding cycling stability contrast to the bare FeF3·0.33H2O. The enhanced electrochemical performance is attributed to the protection of Li3FeF6 layer which reduces the cathode dissolution and interfacial side reactions. Moreover, the agglomeration of first particles in the calcination process is effectively suppressed resulting from the introduction of the Li3FeF6 protective layer, which promotes electrolyte penetration and charge transfer in the composites. It is expected that the strategy can provide a new approach for the modification of other metal fluoride.

  5. Nanotube cathodes.

    SciTech Connect

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  6. Emerging tools for continuous nutrient monitoring networks: Sensors advancing science and water resources protection

    USGS Publications Warehouse

    Pellerin, Brian; Stauffer, Beth A; Young, Dwane A; Sullivan, Daniel J.; Bricker, Suzanne B.; Walbridge, Mark R; Clyde, Gerard A; Shaw, Denice M

    2016-01-01

    Sensors and enabling technologies are becoming increasingly important tools for water quality monitoring and associated water resource management decisions. In particular, nutrient sensors are of interest because of the well-known adverse effects of nutrient enrichment on coastal hypoxia, harmful algal blooms, and impacts to human health. Accurate and timely information on nutrient concentrations and loads is integral to strategies designed to minimize risk to humans and manage the underlying drivers of water quality impairment. Using nitrate sensors as an example, we highlight the types of applications in freshwater and coastal environments that are likely to benefit from continuous, real-time nutrient data. The concurrent emergence of new tools to integrate, manage and share large data sets is critical to the successful use of nutrient sensors and has made it possible for the field of continuous nutrient monitoring to rapidly move forward. We highlight several near-term opportunities for Federal agencies, as well as the broader scientific and management community, that will help accelerate sensor development, build and leverage sites within a national network, and develop open data standards and data management protocols that are key to realizing the benefits of a large-scale, integrated monitoring network. Investing in these opportunities will provide new information to guide management and policies designed to protect and restore our nation’s water resources.

  7. Measurement and mitigation of corrosion on self-contained fluid filled (SCFF) submarine circuits for New York Power Authority: Volume 2 -- Stray electrical current measurements and preliminary design of the cathodic protection system. Final report

    SciTech Connect

    1998-10-01

    In 1987, the New York Power Authority (NYPA) installed a 345-kV submarine cable circuit across Long Island Sound between substations at Davenport Neck and Hempstead Harbor. During design and installation of the cable circuit, utility and cable manufacturers engineers identified corrosion as a possible problem for the cable system. They considered such effects in the cable design and discussed preliminary requirements for a cathodic protection system on Long Island Sound circuit. EPRI cosponsored this review of the corrosion effects with NYPA and Empire State Electric Energy Research Corp. (ESEERCO). Volume 1 of this report discusses the results from an in-depth evaluation of the self-contained fluid-filled (SCFF) cable construction materials and their susceptibility to corrosion. Volume 2 provides extended stray current field measurements and a preliminary design for a cathodic protection system to ensure cable service reliability. This study provides a blueprint for East or West Coast utilities evaluating site-specific corrosion processes and cable circuit protection methods suitable for underwater environments.

  8. A-e Services to perform a cathodic protection survey of the bulk fuel terminals at N. S. C. Pearl Harbor, Hawaii. Volume I. Report for Aug 81-May 82

    SciTech Connect

    Not Available

    1982-06-01

    The purpose of this corrosion survey was to inspect and checkout the existing cathodic protection systems of the underground metallic fuel lines and tanks at the Bulk Fuel Terminal, Naval Supply Center, Pearl Harbor, Hawaii. The corrosion survey was conducted from August 1981 to May of 1982. The corrosion survey was conducted on the following fuel tanks and fuel lines under Contract N62742-81-C-0006. The corrosion evaluation survey was conducted on the following fuel lines under Contract N62742-81-C-0006/P00002.

  9. Cathode phenomena in plasma thrusters

    NASA Astrophysics Data System (ADS)

    Schrade, H. O.; Auweter-Kurtz, M.; Kurtz, H. L.

    1987-05-01

    Processes at the arc cathode attachment decisively determine the entire discharge behavior of almost all arc devices and therefore also of MPD and/or arc jet thrusters. One well known process occurring on spotty arc attachments in a transverse magnetic field is the fact that the cathode spots move or jump in the direction opposite to the Lorentzian rule. In pulsed thruster devices with cold cathodes and very likely also in continuously running thrusters with so-called thermionic-seemingly diffuse attachments of hot surfaces, the arc attachment consists of many high current density spots. These spots can stick or spread upstream and thereby overheat the insulating material of the back-plate of the thruster. In this paper an explanation of the phenomena of spot motion is presented.

  10. Recent Advances in Thermionic Cathodes

    SciTech Connect

    Ives, R. Lawrence; Miram, George; Collins, George; Falce, Louis R.

    2010-11-04

    The latest advances in thermionic cathodes, including scandate and controlled porosity reservoir cathodes, are reviewed. These new cathodes provide improved performance over conventional cathodes for many applications. Advantages and disadvantages are presented.

  11. Development of Lanthanum Ferrite SOFC Cathodes

    SciTech Connect

    Simner, Steve P.; Bonnett, Jeff F.; Canfield, Nathan L.; Meinhardt, Kerry D.; Shelton, Jayne P.; Sprenkle, Vince L.; Stevenson, Jeffry W.

    2003-01-01

    A number of studies have been conducted concerning compositional/microstructural modifications of a Sr-doped lanthanum ferrite (LSF) cathode and protective Sm-doped ceria (SDC) layer in an anode supported solid oxide fuel cell (SOFC). Emphasis was placed on achieving enhanced low temperature (700-800 degrees C) performance, and long-term cell stability. Investigations involved manipulation of the lanthanum ferrite chemistry, addition of noble metal oxygen reduction catalysts, incorporation of active cathode layer compositions containing Co, Fe and higher Sr contents, and attempts to optimize the ceria barrier layer between the LSF cathode and YSZ electrolyte.

  12. Sintered wire cathode

    DOEpatents

    Falce, Louis R.; Ives, R. Lawrence

    2009-06-09

    A porous cathode structure is fabricated from a plurality of wires which are placed in proximity to each other in elevated temperature and pressure for a sintering time. The sintering process produces the porous cathode structure which may be divided into a plurality of individual porous cathodes, one of which may be placed into a dispenser cathode support which includes a cavity for containing a work function reduction material such as BaO, CaO, and Al.sub.2O.sub.3. The work function reduction material migrates through the pores of the porous cathode from a work replenishment surface adjacent to the cavity of the dispenser cathode support to an emitting cathode surface, thereby providing a dispenser cathode which has a uniform work function and therefore a uniform electron emission.

  13. EPA Signs Two Clean Up Decisions in a Continued Effort to Protect Cape Cod Drinking Water

    EPA Pesticide Factsheets

    In its ongoing efforts to protect the Cape Cod aquifer from contamination from historical military training activities, the U.S. Environmental Protection Agency (EPA) has issued final cleanup strategies for two contaminated areas at Camp Edwards.

  14. Pressed boride cathodes

    NASA Technical Reports Server (NTRS)

    Wolski, W.

    1985-01-01

    Results of experimental studies of emission cathodes made from lanthanum, yttrium, and gadolinium hexaborides are presented. Maximum thermal emission was obtained from lanthanum hexaboride electrodes. The hexaboride cathodes operated stably under conditions of large current density power draw, at high voltages and poor vacuum. A microtron electron gun with a lanthanum hexaboride cathode is described.

  15. Application of segmented dental panoramic tomography among children: positive effect of continuing education in radiation protection.

    PubMed

    Pakbaznejad Esmaeili, Elmira; Waltimo-Sirén, Janna; Laatikainen, Tuula; Haukka, Jari; Ekholm, Marja

    2016-05-23

    Dental panoramic tomography is the most frequent examination among 7-12-year olds, according to the Radiation Safety and Nuclear Authority of Finland. At those ages, dental panoramic tomographs (DPTs) are mostly obtained for orthodontic reasons. Children's dose reduction by trimming the field size to the area of interest is important because of their high radiosensitivity. Yet, the majority of DPTs in this age group are still taken by using an adult programme and never by using a segmented programme. The purpose of the present study was to raise the awareness of dental staff with respect to children's radiation safety, to increase the application of segmented and child DPT programmes by further educating the whole dental team and to evaluate the outcome of the educational intervention. A five-step intervention programme, focusing on DPT field limitation possibilities, was carried out in community-based dental care as a part of mandatory continuing education in radiation protection. Application of segmented and child DPT programmes was thereafter prospectively followed up during a 1-year period and compared with our similar data from 2010 using a logistic regression analysis. Application of the child programme increased by 9% and the segmented programme by 2%, reaching statistical significance (odds ratios 1.68; 95% confidence interval 1.23-2.30; p-value < 0.001). The number of repeated exposures remained at an acceptable level. The segmented DPTs were most frequently taken from the maxillary lateral incisor-canine area. The educational intervention resulted in improvement of radiological practice in respect to radiation safety of children during dental panoramic tomography. Segmented and child DPT programmes can be applied successfully in dental practice for children.

  16. Application of segmented dental panoramic tomography among children: positive effect of continuing education in radiation protection

    PubMed Central

    Waltimo-Sirén, Janna; Laatikainen, Tuula; Haukka, Jari; Ekholm, Marja

    2016-01-01

    Objectives: Dental panoramic tomography is the most frequent examination among 7–12-year olds, according to the Radiation Safety and Nuclear Authority of Finland. At those ages, dental panoramic tomographs (DPTs) are mostly obtained for orthodontic reasons. Children's dose reduction by trimming the field size to the area of interest is important because of their high radiosensitivity. Yet, the majority of DPTs in this age group are still taken by using an adult programme and never by using a segmented programme. The purpose of the present study was to raise the awareness of dental staff with respect to children's radiation safety, to increase the application of segmented and child DPT programmes by further educating the whole dental team and to evaluate the outcome of the educational intervention. Methods: A five-step intervention programme, focusing on DPT field limitation possibilities, was carried out in community-based dental care as a part of mandatory continuing education in radiation protection. Application of segmented and child DPT programmes was thereafter prospectively followed up during a 1-year period and compared with our similar data from 2010 using a logistic regression analysis. Results: Application of the child programme increased by 9% and the segmented programme by 2%, reaching statistical significance (odds ratios 1.68; 95% confidence interval 1.23–2.30; p-value < 0.001). The number of repeated exposures remained at an acceptable level. The segmented DPTs were most frequently taken from the maxillary lateral incisor–canine area. Conclusions: The educational intervention resulted in improvement of radiological practice in respect to radiation safety of children during dental panoramic tomography. Segmented and child DPT programmes can be applied successfully in dental practice for children. PMID:27142159

  17. 95 GHz gyrotron with ferroelectric cathode.

    PubMed

    Einat, M; Pilossof, M; Ben-Moshe, R; Hirshbein, H; Borodin, D

    2012-11-02

    Ferroelectric cathodes were reported as a feasible electron source for microwave tubes. However, due to the surface plasma emission characterizing this cathode, operation of millimeter wave tubes based on it remains questionable. Nevertheless, the interest in compact high power sources of millimeter waves and specifically 95 GHz is continually growing. In this experiment, a ferroelectric cathode is used as an electron source for a gyrotron with the output frequency extended up to 95 GHz. Power above a 5 kW peak and ~0.5 μs pulses are reported; a duty cycle of 10% is estimated to be achievable.

  18. Pilot-scale continuous synthesis of a vanadium-doped LiFePO4/C nanocomposite high-rate cathodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Johnson, Ian D.; Lübke, Mechthild; Wu, On Ying; Makwana, Neel M.; Smales, Glen J.; Islam, Husn U.; Dedigama, Rashmi Y.; Gruar, Robert I.; Tighe, Christopher J.; Scanlon, David O.; Corà, Furio; Brett, Dan J. L.; Shearing, Paul R.; Darr, Jawwad A.

    2016-01-01

    A high performance vanadium-doped LiFePO4 (LFP) electrode is synthesized using a continuous hydrothermal method at a production rate of 6 kg per day. The supercritical water reagent rapidly generates core/shell nanoparticles with a thin, continuous carbon coating on the surface of LFP, which aids electron transport dynamics across the particle surface. Vanadium dopant concentration has a profound effect on the performance of LFP, where the composition LiFe0.95V0.05PO4, achieves a specific discharge capacity which is among the highest in the comparable literature (119 mA h g-1 at a discharge rate of 1500 mA g-1). Additionally, a combination of X-ray absorption spectroscopy analysis and hybrid-exchange density functional theory, suggest that vanadium ions replace both phosphorous and iron in the structure, thereby facilitating Li+ diffusion due to Li+ vacancy generation and changes in the crystal structure.

  19. A Continued Study of Polymeric Materials for Protection Against Chemical and Biological Contaminants and Halogen Oxidants for Immobilization in Protective Materials and Coatings

    DTIC Science & Technology

    2013-03-01

    laboratory testing of materials developed during the project, as well as to Dr. M. E. Shirtliff at the Center for Biofilm Engineering at Montana State...unlimited. 88ABW-2013-1126, 8 March 2013. Engineering at Montana State University coated polycarbonate slides with our material and tested them...AFRL-RX-TY-TR-2012-0027 A CONTINUED STUDY OF POLYMERIC MATERIALS FOR PROTECTION AGAINST CHEMICAL AND BIOLOGICAL CONTAMINANTS AND HALOGEN

  20. U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA) ENVIRONMENTAL TECHNOLOGY VERIFICATION (ETV) PROGRAM: MERCURY CONTINUOUS EMISSION MONITORS

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) Environmental Technology Verification (ETV) program evaluates the performance of innovative air, water, pollution prevention and monitoring technologies that have the potential to improve human health and the environment. This techn...

  1. U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA) ENVIRONMENTAL TECHNOLOGY VERIFICATION (ETV) PROGRAM: MERCURY CONTINUOUS EMISSION MONITORS

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) Environmental Technology Verification (ETV) program evaluates the performance of innovative air, water, pollution prevention and monitoring technologies that have the potential to improve human health and the environment. This techn...

  2. Stranger danger? Women's self-protection intent and the continuing stigma of online dating.

    PubMed

    Cali, Billie E; Coleman, Jill M; Campbell, Catherine

    2013-12-01

    The present study examines the stigma associated with online relationship initiation and its relation to women's self-protective behavior. Self-protective behaviors are those an individual engages in to avoid becoming a victim of dating violence. Female participants from a Midwestern university (N=82) were asked to read scenarios describing a hypothetical date. In one scenario, the prospective date was only previously known through an online social networking site, while in the other scenario, the date was previously known through brief face-to-face interaction. After reading the scenario, participants rated the importance of engaging in self-protection behaviors if they were in the date situation being described. As we predicted, participants assigned greater importance to self-protective behavior after reading the online meeting scenario than the face-to-face scenario. This tendency was especially strong among participants who had never been on a date with someone they had met online.

  3. Virtual Cathode Oscillator Study.

    DTIC Science & Technology

    1984-11-01

    emission region then con- sists of an array of fibers perpendicular to a conducting cathode surface . A surface flashover along the individual fibers...acts like the Corona electron source developed by Helionetics13 for laser pre-ioniza- tion. The axial surface flashover mechanism is more desirable than...the conventional cold cathode emission process, because production of plasma in this manner inhibits the formation of surface cathode spots. 7 75

  4. Bifurcations of edge states—topologically protected and non-protected—in continuous 2D honeycomb structures

    NASA Astrophysics Data System (ADS)

    Fefferman, C. L.; Lee-Thorp, J. P.; Weinstein, M. I.

    2016-03-01

    Edge states are time-harmonic solutions to energy-conserving wave equations, which are propagating parallel to a line-defect or ‘edge’ and are localized transverse to it. This paper summarizes and extends the authors’ work on the bifurcation of topologically protected edge states in continuous two-dimensional (2D) honeycomb structures. We consider a family of Schrödinger Hamiltonians consisting of a bulk honeycomb potential and a perturbing edge potential. The edge potential interpolates between two different periodic structures via a domain wall. We begin by reviewing our recent bifurcation theory of edge states for continuous 2D honeycomb structures (http://arxiv.org/abs/1506.06111). The topologically protected edge state bifurcation is seeded by the zero-energy eigenstate of a one-dimensional Dirac operator. We contrast these protected bifurcations with (more common) non-protected bifurcations from spectral band edges, which are induced by bound states of an effective Schrödinger operator. Numerical simulations for honeycomb structures of varying contrasts and ‘rational edges’ (zigzag, armchair and others), support the following scenario: (a) for low contrast, under a sign condition on a distinguished Fourier coefficient of the bulk honeycomb potential, there exist topologically protected edge states localized transverse to zigzag edges. Otherwise, and for general edges, we expect long lived edge quasi-modes which slowly leak energy into the bulk. (b) For an arbitrary rational edge, there is a threshold in the medium-contrast (depending on the choice of edge) above which there exist topologically protected edge states. In the special case of the armchair edge, there are two families of protected edge states; for each parallel quasimomentum (the quantum number associated with translation invariance) there are edge states which propagate in opposite directions along the armchair edge.

  5. Mechanistic Insight in the Function of Phosphite Additives for Protection of LiNi 0.5 Co 0.2 Mn 0.3 O 2 Cathode in High Voltage Li-Ion Cells

    SciTech Connect

    He, Meinan; Su, Chi-Cheung; Peebles, Cameron; Feng, Zhenxing; Connell, Justin G.; Liao, Chen; Wang, Yan; Shkrob, Ilya A.; Zhang, Zhengcheng

    2016-05-11

    Triethlylphosphite (TEP) and tris(2,2,2-trifluoroethyl) phosphite (TTFP) have been evaluated as electrolyte additives for high-voltage Li-ion battery cells using a Ni-rich layered cathode material LiNi0.5Co0.2Mn0.3O2 (NCM523) and the conventional carbonate electrolyte. The repeated charge/discharge cycling for cells containing 1 wt% of these additives was performed using an NCM523/graphite full cell operated at the voltage window from 3.0 to 4.6 V. During the initial charge process, these additives decompose on the cathode surface at a lower oxidation potential than the baseline electrolyte. Impedance spectroscopy and post-test analyses indicate the formation of protective coatings by both additives on the cathode surface that prevent oxidative breakdown of the electrolyte. However, only TTFP containing cells demonstrate the improved capacity retention and Coulombic efficiency. For TEP, the protective coating is also formed, but low Li+ ion mobility through the interphase layer results in inferior performance. These observations are rationalized through the inhibition of electrocatalytic centers present on the cathode surface and the formation of organophosphate deposits isolating the cathode surface from the electrolyte. The difference between the two phosphites clearly originates in the different properties of the resulting phosphate coatings, which may be in Li+ ion conductivity through such materials.

  6. Hypertension and cardiovascular remodelling in rats exposed to continuous light: protection by ACE-inhibition and melatonin.

    PubMed

    Simko, Fedor; Pechanova, Olga; Repova Bednarova, Kristina; Krajcirovicova, Kristina; Celec, Peter; Kamodyova, Natalia; Zorad, Stefan; Kucharska, Jarmila; Gvozdjakova, Anna; Adamcova, Michaela; Paulis, Ludovit

    2014-01-01

    Exposure of rats to continuous light attenuates melatonin production and results in hypertension development. This study investigated whether hypertension induced by continuous light (24 hours/day) exposure induces heart and aorta remodelling and if these alterations are prevented by melatonin or angiotensin converting enzyme inhibitor captopril. Four groups of 3-month-old male Wistar rats (10 per group) were treated as follows for six weeks: untreated controls, exposed to continuous light, light-exposed, and treated with either captopril (100 mg/kg/day) or melatonin (10 mg/kg/day). Exposure to continuous light led to hypertension, left ventricular (LV) hypertrophy and fibrosis, and enhancement of the oxidative load in the LV and aorta. Increase in systolic blood pressure by continuous light exposure was prevented completely by captopril and partially by melatonin. Both captopril and melatonin reduced the wall thickness and cross-sectional area of the aorta and reduced the level of oxidative stress. However, only captopril reduced LV hypertrophy development and only melatonin reduced LV hydroxyproline concentration in insoluble and total collagen in rats exposed to continuous light. In conclusion, captopril prevented LV hypertrophy development in the continuous light-induced hypertension model, while only melatonin significantly reduced fibrosis. This antifibrotic action of melatonin may be protective in hypertensive heart disease.

  7. Continuing Change in Newark: To Protect Reform, Chris Cerf Builds Collaborative Relationships

    ERIC Educational Resources Information Center

    Colvin, Richard Lee

    2016-01-01

    This article reports on the efforts of Christopher Cerf, the state-appointed superintendent of Newark Public Schools (New Jersey), to protect reform and build collaborative relationships. His tenure followed the controversial leadership of the former superintendent that had enacted a series of unpopular initiatives, including a new citywide…

  8. Continuing Change in Newark: To Protect Reform, Chris Cerf Builds Collaborative Relationships

    ERIC Educational Resources Information Center

    Colvin, Richard Lee

    2016-01-01

    This article reports on the efforts of Christopher Cerf, the state-appointed superintendent of Newark Public Schools (New Jersey), to protect reform and build collaborative relationships. His tenure followed the controversial leadership of the former superintendent that had enacted a series of unpopular initiatives, including a new citywide…

  9. Protection against Amorimia septentrionalis poisoning in goats by the continuous administration of sodium monofluoroacetate-degrading bacteria.

    PubMed

    da Silva, Layze C A; Pessoa, Danielle A N; Lopes, Jose R G; de Albuquerque, Laio G; da Silva, Leomyr S A; Garino Junior, Felicio; Riet-Correa, Franklin

    2016-03-01

    The intraruminal inoculation of sodium monofluoroacetate (MFA)-degrading bacteria has been proposed as a method to prevent poisoning by MFA-containing plants. In previous experiments, MFA-degrading bacteria were inoculated intraruminally before or concurrent with plant challenge, with both strategies conferring partial protection to poisoning. To evaluate the protection to Amorimia septentrionalis poisoning provided by the continuous inoculation of MFA-degrading bacteria isolated from plants and soils, 18 goats were divided into three experimental groups of six animals each: Group 1 goats received daily doses of a mixture of Paenibacillus sp. and Cupriavidus sp., and Group 2 goats received a mixture of Ralstonia sp. and Burkholderia sp., for 40 days, while Group 3 goats were not inoculated. Ten days after initiation of bacterial inoculation in Groups 1 and 2, all goats were challenged daily with 5 g/kg body weight of green leaves from A. septentrionalis. Four goats from Group 1 consumed the leaves throughout the 30-day consumption period and showed clinical signs such as transient tachycardia and engorgement of the jugular. The two remaining animals from Group 1 showed obvious signs of intoxication, and plant administration was suspended on days 17 and 19. The goats in Group 2 consumed the leaves throughout the 30-day study without showing signs of poisoning. The goats from Group 3 (control) manifested severe clinical signs of poisoning between the 3rd and 10th days following the start of the A. septentrionalis challenge. Under the conditions of this experiment continuous intraruminal administration of Ralstonia sp. and Burkholderia sp. provided complete protection to poisoning by A. septentrionalis in goats, while continuous intraruminal administration of Paenibacillus sp. and Cupriavidus sp. provided partial protection.

  10. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    SciTech Connect

    Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

    2002-03-31

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. This period has continued to address the problem of making dense 1/2 to 5 {micro}m thick dense layers on porous substrates (the cathode LSM). Our current status is that we are making structures of 2-5 cm{sup 2} in area, which consist of either dense YSZ or CGO infiltrated into a 2-5 {micro}m thick 50% porous layer made of either nanoncrystalline CGO or YSZ powder. This composite structure coats a macroporous cathode or anode; which serves as the structural element of the bi-layer structure. These structures are being tested as SOFC elements. A number of structures have been evaluated both as symmetrical and as button cell configuration. Results of this testing indicates that the cathodes contribute the most to cell losses for temperatures below 750 C. In this investigation different cathode materials were studied using impedance spectroscopy of symmetric cells and IV characteristics of anode supported fuel cells. Cathode materials studied included La{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF), La{sub 0.7}Sr{sub 0.2}MnO{sub 3} (LSM), Pr{sub 0.8}Sr{sub 0.2}Fe{sub 0.8}O{sub 3} (PSCF), Sm{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF), and Yb{sub .8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF). A new technique for filtering the Fourier transform of impedance data was used to increase the sensitivity of impedance analysis. By creating a filter specifically for impedance spectroscopy the resolution was increased. The filter was tailored to look for specific circuit elements like R//C, Warburg, or constant phase elements. As many as four peaks can be resolved using the filtering technique on symmetric cells. It may be possible to relate the different peaks to material parameters, like the oxygen exchange coefficient. The cathode grouped in order from lowest to highest ASR is

  11. Business continuity, emergency planning and special needs: How to protect the vulnerable.

    PubMed

    Reilly, Daniel

    2015-01-01

    Emergencies and disasters affect all segments of the population. Some segments are more at risk during the emergency response and recovery efforts owing to vulnerabilities that increase the risk of harm. These vulnerabilities are due to individuals' disabilities, which must be incorporated into emergency and business continuity planning. Some disabilities are obvious, such as impaired vision, hearing or mobility, while other are less evident, but equally disabling, such as cognitive disorders, geographical or language isolation, and numerous age-related factors. Taken together when creating emergency or business continuity plans, the issues identified as disabilities can be grouped by functionality and termed as special needs. This paper will detail the identification of special needs populations, explain how these persons are vulnerable during the emergency or disaster response and recovery process, and provide examples of how to partner with individuals within identified special needs populations to improve the planning process.

  12. Do continued antidepressants protect against dementia in patients with severe depressive disorder?

    PubMed

    Kessing, Lars Vedel; Forman, Julie Lyng; Andersen, Per Kragh

    2011-11-01

    Studies on humans show that depressive disorder is associated with an increased risk of developing cognitive dysfunction, and animal studies suggest that antidepressants may have neuroprotective abilities. On the basis of these observations, it was hypothesized that treatment with antidepressants may decrease the risk of developing dementia in patients with depression. We investigated whether continued treatment with antidepressants is associated with a decreased rate of dementia in a population of patients discharged from psychiatric healthcare service with a diagnosis of depression. We used register data on all prescribed antidepressants in all patients discharged from psychiatric healthcare service with a diagnosis of depression and with subsequent diagnoses of dementia in Denmark from 1995 to 2005. A total of 37 658 patients with a diagnosis of depression at their first psychiatric contact and who were exposed to antidepressants after discharge were included in the study. A total of 2007 patients (5.3%) were subsequently diagnosed with dementia of any kind. The rate of dementia decreased during periods of two or more prescriptions of older antidepressants compared with the period of only one prescription of older antidepressants [relative risk (RR)=0.83 (95% confidence interval (CI)=0.70-0.98)]. This finding was replicated with Alzheimer's disease as the outcome [RR=0.66 (95% CI=0.47-0.94)] but not with dementia of other kinds as the outcome [RR=0.88 (95% CI=0.73-1.06)]. In contrast, during periods of continued use of selective serotonin reuptake inhibitors or newer nonselective serotonin reuptake inhibitors, the rate of dementia was not decreased, regardless of the subtype of dementia. It was concluded that continued long-term treatment with older antidepressants is associated with a reduced rate of dementia in patients treated in psychiatric healthcare settings, whereas continued treatment with other kinds of antidepressants is not. Methodological reasons for

  13. Promoting employee health by integrating health protection, health promotion, and continuous improvement: a longitudinal quasi-experimental intervention study.

    PubMed

    von Thiele Schwarz, Ulrica; Augustsson, Hanna; Hasson, Henna; Stenfors-Hayes, Terese

    2015-02-01

    To test the effects of integrating health protection and health promotion with a continuous improvement system (Kaizen) on proximal employee outcomes (health promotion, integration, and Kaizen) and distal outcomes (workability, productivity, self-rated health and self-rated sickness absence). Twelve units in a county hospital in Sweden were randomized to control or intervention groups using a quasiexperimental study design. All staff (approximately 500) provided self-ratings in questionnaires at baseline, and a 12- and 24-month follow-up (response rate, 79% to 87.5%). There was a significant increase in the proximal outcomes over time in the intervention group compared with the control group, and a trend toward improvement in the distal outcomes workability and productivity. Integration seems to promote staff engagement in health protection and promotion, as well as to improve their understanding of the link between work and health.

  14. An improved reservoir oxide cathode

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxia; Liao, Xianheng; Luo, Jirun; Zhao, Qinglan

    2005-09-01

    A new type of reservoir oxide cathode has been developed in IECAS. The emission characteristics of the cathode are tested. The results show the new cathode has higher emission current density and better resistance to poisoning at same operating condition compared with those of conventional reservoir oxide cathode.

  15. Lightweight Cathodes For Nickel Batteries

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    1996-01-01

    Lightweight cathodes for rechargeable nickel-based electrochemical cells undergoing development. In cathodes, mats of nickel fibers are substrates providing structural support of, and electrical contact with, active cathode material. Offers specific energies greater than sintered nickel plaque cathodes. Electrodes used in rechargeable batteries for applications in which weight major concern, including laptop computers, cellular phones, flashlights, soldiers' backpacks, and electric vehicles.

  16. Cathodes - Technological review

    NASA Astrophysics Data System (ADS)

    Cherkouk, Charaf; Nestler, Tina

    2014-06-01

    Lithium cobalt oxide (LiCoO2) was already used in the first commercialized Li-ion battery by SONY in 1990. Still, it is the most frequently used cathode material nowadays. However, LiCoO2 is intrinsically unstable in the charged state, especially at elevated temperatures and in the overcharged state causing volume changes and transport limitation for high power batteries. In this paper, some technological aspects with large impact on cell performance from the cathode material point of view will be reviewed. At first it will be focused on the degradation processes and life-time mechanisms of the cathode material LiCoO2. Electrochemical and structural results on commercial Li-ion batteries recorded during the cycling will be discussed. Thereafter, advanced nanomaterials for new cathode materials will be presented.

  17. Cathodes - Technological review

    SciTech Connect

    Cherkouk, Charaf; Nestler, Tina

    2014-06-16

    Lithium cobalt oxide (LiCoO{sub 2}) was already used in the first commercialized Li-ion battery by SONY in 1990. Still, it is the most frequently used cathode material nowadays. However, LiCoO{sub 2} is intrinsically unstable in the charged state, especially at elevated temperatures and in the overcharged state causing volume changes and transport limitation for high power batteries. In this paper, some technological aspects with large impact on cell performance from the cathode material point of view will be reviewed. At first it will be focused on the degradation processes and life-time mechanisms of the cathode material LiCoO{sub 2}. Electrochemical and structural results on commercial Li-ion batteries recorded during the cycling will be discussed. Thereafter, advanced nanomaterials for new cathode materials will be presented.

  18. Neobenedenia melleni-Specific Antibodies Are Associated with Protection after Continuous Exposure in Mozambique Tilapia

    PubMed Central

    Kishimori, Jennifer M.; Takemura, Akihiro; Leong, Jo-Ann C.

    2015-01-01

    Neobenedenia melleni is a significant monogenean pathogen of fish in aquaculture facilities and public aquaria. Immunity after exposure to live N. melleni is well established, but the mechanisms of immunity remain unclear. In this study, tilapia (Oreochromis mossambicus) were continuously exposed to N. melleni over a four-month period and assessed for immunity as determined by a reduction in the number of parasites dislodged from the experimental animals during freshwater immersion. Specific mucosal and systemic antibody levels were by determined via enzyme-linked immunosorbent assay. At 45 days postexposure (DPE), fish displayed high parasite loads and baseline levels of mucosal antibodies. At 102 and 120 DPE parasite loads were significantly decreased, and antibody levels were significantly increased for mucus and plasma samples. The correlation between immunity (reduction in parasite load) and an increased humoral antibody response suggests a key role of antibody in the immune response. This is the first report of immunity against N. melleni that is associated with specific mucosal or systemic antibodies. PMID:25756055

  19. Oxide Cathode Mechanisms: Electronic and Structural Features of Oxide Cathode Surfaces.

    DTIC Science & Technology

    1985-01-01

    journals shall ensue as follows: (i) in form by Elsevier under the title Isorption and (Cont) 17. COSATI CODES 18. SUBJECT TERMS ( Continue on reverse it...Lminescence from Oxide Surfaces 19. ABSTRACT ( Continue on reverse if necesary and identify by block number) Continued fran Blk 11: and Structural...Features of Oxide Cathode Surfaces. Continued fran Blk 16: Catalysis om Oxide Surfaces" (ii) in JCS Faraday Transaction I as two scientific papers

  20. Extended-testing of xenon ion thruster hollow cathodes

    NASA Technical Reports Server (NTRS)

    Sarver-Verhey, Timothy R.

    1992-01-01

    A hollow cathode wear-test of 508 hours was successfully completed at an emission current of 23.0 A and a xenon flow rate of 10 Pa-L/s. This test was the continuation of a hollow cathode contamination investigation. Discharge voltage was stable at 16.7 V. The cathode temperature averaged 1050 C with a 7 percent drop during the wear-test. Discharge ignition voltage was found to be approximately 20 V and was repeatable over four starts. Post-test analyses of the hollow cathode found a much improved internal cathode condition with respect to earlier wear-test cathodes. Negligible tungsten movement occurred and no formation of mono-barium tungsten was observed. These results correlated with an order-of-magnitude reduction in propellant feed-system leakage rate. Ba2CaWO6 and extensive calcium crystal formation occurred on the upstream end of the insert. Ba-Ca compound depositions were found on the Mo insert collar, on the Re electrical leads, and in the gap between the insert and cathode wall. This wear-test cathode was found to be in the best internal condition and had the most stable operating performance of any hollow cathode tested during this contamination investigation.

  1. A study of cathode erosion in high power arcjets

    NASA Astrophysics Data System (ADS)

    Harris, William Jackson, III

    Cathode erosion continues to be one of the predominant technology concerns for high power arcjets. This study will show that cathode erosion in these devices is significantly affected by several mitigating factors, including propellant composition, propellant flowrate, current level, cathode material, and power supply current ripple. In a series of 50-hour and 100-hour long duration experiments, using a water-cooled 30 kilowatt laboratory arcjet, variations in the steady-state cathode erosion rate were characterized for each of these factors using nitrogen propellant at a fixed arc current of 250 Amperes. A complementary series of measurements was made using hydrogen propellant at an arc current of 100 Amperes. The cold cathode erosion rate was also differentiated from the steady-state cathode erosion rate in a series of multi-start cathode erosion experiments. Results of these measurements are presented, along with an analysis of the significant effects of current ripple on arcjet cathode erosion. As part of this study, over a dozen refractory cathode materials were evaluated to measure their resistance to arcjet cathode erosion. Among the materials tested were W-ThO2(1%, 2%, 4%), poly and mono-crystalline W, W-LaB6, W-La2O3, W-BaO2, W-BaCaAl2O4, W-Y2O3, and ZrB2. Based on these measurements, several critical material properties were identified, such work function, density, porosity, melting point, and evaporation rate. While the majority of the materials failed to outperform traditional W-ThO2, these experimental results are used to develop a parametric model of the arcjet cathode physics. The results of this model, and the results of a finite-element thermal analysis of the arcjet cathode, are presented to better explain the relative performance of the materials tested.

  2. Suppressing capacity fading and voltage decay of Li-rich layered cathode material by a surface nano-protective layer of CoF2 for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Chong, Shaokun; Chen, Yuanzhen; Yan, Wuwei; Guo, Shengwu; Tan, Qiang; Wu, Yifang; Jiang, Tao; Liu, Yongning

    2016-11-01

    Li-rich layered oxides have been regarded as valuable cathode materials for high energy density lithium-ion batteries. However, high initial irreversible capacity, bad rate capability, as well as serious capacity fading and voltage decay hinder their commercial application. In this paper, a nano CoF2 protective layer is coated on the surface of Li1.2Ni0.2Mn0.6O2 via a facial wet chemistry method. A high initial discharge capacity of 264.4 mAh g-1 is obtained for 0.5% CoF2-coated sample and 259.1 mAh g-1 for 1% CoF2-coated sample owing to the suppression of irreversible release of O2 and the contribution of electrochemical conversion of CoF2/LiF. Furthermore, 1% CoF2-coated sample exhibits the excellent rate capability of 167.5 mAh g-1 at 5 C rate, the superior cycling stability with the capacity retention of 241.0 mAh g-1 and the ameliorative voltage drop of 0.312 V at 0.1C after 100 cycles. The enhanced rate performance as well as stability of capacity and voltage can be attributed to the nano coatings which inhibit the electrolyte-electrode side reaction, enhance the electrochemical kinetics and mitigate structure transition from layered to spinel phase.

  3. Alternative methods for evaluating corrosion deterioration on existing USTs prior to upgrading with cathodic protection as defined in ASTM standard practice ES40-94

    SciTech Connect

    Bushman, J.B.

    1995-12-31

    In November, 1994 ASTM approved the issuance of Emergency Standard ES40-94 defining new means for evaluating the corrosion condition of existing USTs. This paper presents the background information which lead to the formation of a committee which undertook the development of the new standard, general descriptions of each of the methodologies provided, information on the standard approval process and an outline of the continuing work effort to reissue the standard with minor editorial modifications as a regular ASTM standard.

  4. Metrology in arc plasmas - A new cathode

    NASA Astrophysics Data System (ADS)

    Croche, R.

    1980-02-01

    A new radiating source consisting of an electric arc under argon pressure is described, with power varying between about 0.2 and 1.5 kW, and with the plasma furnishing a continuous spectrum between 115 and 350 nm. The arc functions from 5 to 50 A, with a voltage varying between 30 and 35 V. The cathode of the transfer arc is described in detail, including such advantages as easy igniting of the arc and the possibility of re-sharpening the tip of the cathode. Most important, the new 'knife-shaped' form of the tungsten cathode has improved the stability and reproducibility of the ultraviolet continuum emitted by the plasma of the arc, which is used at the French National Institute of Metrology as a transfer standard of spectral radiance in the vacuum ultraviolet.

  5. Cathode materials review

    SciTech Connect

    Daniel, Claus Mohanty, Debasish Li, Jianlin Wood, David L.

    2014-06-16

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO{sub 2} cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  6. Cathode materials review

    NASA Astrophysics Data System (ADS)

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

    2014-06-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  7. A-E Services to Perform a Cathodic Protection Survey of the Bulk Fuel Terminals at N.S.C. Pearl Harbor, Hawaii. Volume I.

    DTIC Science & Technology

    1982-06-01

    cast iron fire water mains around the Upper Tanks are not electrically continuous section to section. These cast iron water mains are also electrically...rectifier and fourteen (14) 4"x40" graphite anodes, be installed southwest of Pumphouse 59. -294- B. It. is recommended that the cast iron fire water mains...between the cast iron fire water main and the POL lines near Fire Hydrant #468. C. It is reconmended that an insulator be installed at each of the

  8. Microscale gradients of oxygen, hydrogen peroxide, and pH in freshwater cathodic biofilms.

    PubMed

    Babauta, Jerome T; Nguyen, Hung Duc; Istanbullu, Ozlem; Beyenal, Haluk

    2013-07-01

    Cathodic reactions in biofilms employed in sediment microbial fuel cells is generally studied in the bulk phase. However, the cathodic biofilms affected by these reactions exist in microscale conditions in the biofilm and near the electrode surface that differ from the bulk phase. Understanding these microscale conditions and relating them to cathodic biofilm performance is critical for better-performing cathodes. The goal of this research was to quantify the variation in oxygen, hydrogen peroxide, and the pH value near polarized surfaces in river water to simulate cathodic biofilms. We used laboratory river-water biofilms and pure culture biofilms of Leptothrix discophora SP-6 as two types of cathodic biofilms. Microelectrodes were used to quantify oxygen concentration, hydrogen peroxide concentration, and the pH value near the cathodes. We observed the correlation between cathodic current generation, oxygen consumption, and hydrogen peroxide accumulation. We found that the 2 e(-) pathway for oxygen reduction is the dominant pathway as opposed to the previously accepted 4 e(-) pathway quantified from bulk-phase data. Biofouling of initially non-polarized cathodes by oxygen scavengers reduced cathode performance. Continuously polarized cathodes could sustain a higher cathodic current longer despite contamination. The surface pH reached a value of 8.8 when a current of only -30 μA was passed through a polarized cathode, demonstrating that the pH value could also contribute to preventing biofouling. Over time, oxygen-producing cathodic biofilms (Leptothrix discophora SP-6) colonized on polarized cathodes, which decreased the overpotential for oxygen reduction and resulted in a large cathodic current attributed to manganese reduction. However, the cathodic current was not sustainable.

  9. Microscale Gradients of Oxygen, Hydrogen Peroxide, and pH in Freshwater Cathodic Biofilms

    PubMed Central

    Babauta, Jerome T.; Nguyen, Hung Duc; Istanbullu, Ozlem

    2014-01-01

    Cathodic reactions in biofilms employed in sediment microbial fuel cells is generally studied in the bulk phase. However, the cathodic biofilms affected by these reactions exist in microscale conditions in the biofilm and near the electrode surface that differ from the bulk phase. Understanding these microscale conditions and relating them to cathodic biofilm performance is critical for better-performing cathodes. The goal of this research was to quantify the variation in oxygen, hydrogen peroxide, and the pH value near polarized surfaces in river water to simulate cathodic biofilms. We used laboratory river-water biofilms and pure culture biofilms of Leptothrix discophora SP-6 as two types of cathodic biofilms. Microelectrodes were used to quantify oxygen concentration, hydrogen peroxide concentration, and the pH value near the cathodes. We observed the correlation between cathodic current generation, oxygen consumption, and hydrogen peroxide accumulation. We found that the 2e− pathway for oxygen reduction is the dominant pathway as opposed to the previously accepted 4e− pathway quantified from bulk-phase data. Biofouling of initially non-polarized cathodes by oxygen scavengers reduced cathode performance. Continuously polarized cathodes could sustain a higher cathodic current longer despite contamination. The surface pH reached a value of 8.8 when a current of only −30 μA was passed through a polarized cathode, demonstrating that the pH value could also contribute to preventing biofouling. Over time, oxygen-producing cathodic biofilms (Leptothrix discophora SP-6) colonized on polarized cathodes, which decreased the overpotential for oxygen reduction and resulted in a large cathodic current attributed to manganese reduction. However, the cathodic current was not sustainable. PMID:23766295

  10. Miniaturized cathodic arc plasma source

    DOEpatents

    Anders, Andre; MacGill, Robert A.

    2003-04-15

    A cathodic arc plasma source has an anode formed of a plurality of spaced baffles which extend beyond the active cathode surface of the cathode. With the open baffle structure of the anode, most macroparticles pass through the gaps between the baffles and reflect off the baffles out of the plasma stream that enters a filter. Thus the anode not only has an electrical function but serves as a prefilter. The cathode has a small diameter, e.g. a rod of about 1/4 inch (6.25 mm) diameter. Thus the plasma source output is well localized, even with cathode spot movement which is limited in area, so that it effectively couples into a miniaturized filter. With a small area cathode, the material eroded from the cathode needs to be replaced to maintain plasma production. Therefore, the source includes a cathode advancement or feed mechanism coupled to cathode rod. The cathode also requires a cooling mechanism. The movable cathode rod is housed in a cooled metal shield or tube which serves as both a current conductor, thus reducing ohmic heat produced in the cathode, and as the heat sink for heat generated at or near the cathode. Cooling of the cathode housing tube is done by contact with coolant at a place remote from the active cathode surface. The source is operated in pulsed mode at relatively high currents, about 1 kA. The high arc current can also be used to operate the magnetic filter. A cathodic arc plasma deposition system using this source can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  11. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  12. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2015-01-13

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  13. Synopsis of Cathode #4 Activation

    SciTech Connect

    Kwan, Joe; Ekdahl, C.; Harrison, J.; Kwan, J.; Leitner, M.; McCruistian, T.; Mitchell, R.; Prichard, B.; Roy, P.

    2006-05-26

    The purpose of this report is to describe the activation of the fourth cathode installed in the DARHT-II Injector. Appendices have been used so that an extensive amount of data could be included without danger of obscuring important information contained in the body of the report. The cathode was a 612 M type cathode purchased from Spectra-Mat. Section II describes the handling and installation of the cathode. Section III is a narrative of the activation based on information located in the Control Room Log Book supplemented with time plots of pertinent operating parameters. Activation of the cathode was performed in accordance with the procedure listed in Appendix A. The following sections provide more details on the total pressure and constituent partial pressures in the vacuum vessel, cathode heater power/filament current, and cathode temperature.

  14. Cathode development for a rechargeable lithium ion battery

    SciTech Connect

    Sengupta, D.

    1994-04-01

    Lithium ion rechargeable batteries have been the subject of much research since 1990, when Sony announced their intention to market such a battery. The cathode of this battery continues to pose many processing questions, in terms of additive content and fabrication procedure. Some of these questions have been examined in this report. Experiments involving several additives in varying amounts with lithium cobalite powder, the primary material in the battery cathode have been performed. A brief analysis of the Sony battery was also completed.

  15. International Space Station Cathode Life Testing Status

    NASA Technical Reports Server (NTRS)

    Sarver-Verhey, Timothy R.; Soulas, George C.

    1998-01-01

    To demonstrate adequate lifetime and performance capabilities of a hollow cathode for use on the International Space Station (ISS) plasma contactor system, life tests of multiple hollow cathode assemblies (HCAs) were initiated at operating conditions simulating on-orbit operation. Three HCAs are presently being tested. These HCAs are operated with a continuous 6 sccm xenon flow rate and 3 A anode current. Emission current requirements are simulated with a square waveform consisting of 50 minutes at a 2.5 A emission current and 40 minutes with no emission current. As of July 1998, these HCAs have accumulated between 1 1,700 and 14,200 hours. While there have been changes in operatin, behavior the three HCAs continue to operate stably within ISS specifications and are expected to demonstrate the required lifetime.

  16. Air cathode structure manufacture

    DOEpatents

    Momyer, William R.; Littauer, Ernest L.

    1985-01-01

    An improved air cathode structure for use in primary batteries and the like. The cathode structure includes a matrix active layer, a current collector grid on one face of the matrix active layer, and a porous, nonelectrically conductive separator on the opposite face of the matrix active layer, the collector grid and separator being permanently bonded to the matrix active layer. The separator has a preselected porosity providing low IR losses and high resistance to air flow through the matrix active layer to maintain high bubble pressure during operation of the battery. In the illustrated embodiment, the separator was formed of porous polypropylene. A thin hydrophobic film is provided, in the preferred embodiment, on the current collecting metal grid.

  17. Improved Rare-Earth Emitter Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  18. Conducting polymer PPy nanowire-based triboelectric nanogenerator and its application for self-powered electrochemical cathodic protection† †Electronic supplementary information (ESI) available: Microscope images, OCP variation and Tafel curves of Q235 carbon steel which is connected to the cathodic protection system driven by W-TENG are reported here. See DOI: 10.1039/c6sc02562e Click here for additional data file.

    PubMed Central

    Cui, Siwen; Zheng, Youbin; Liang, Jun

    2016-01-01

    As a new type of energy harvesting device, the triboelectric nanogenerator (TENG) can convert almost all kinds of mechanical energy into electricity based on the coupling of triboelectrification and electrostatic induction. Here, a novel TENG is constructed with a conducting polymer polypyrrole nanowire (PPy NW) electrode, which is prepared by an electrochemical polymerization method with anodic aluminum oxide (AAO) as the template. The PPy NW-based TENG shows high output performance with a maximum short circuit current density of 23.4 mA m–2 and output voltage of 351 V, which can light 372 commercial red LEDs. Moreover, a self-powered anticorrosion system powered by the PPy NW-based TENG is designed, which can provide extra electrons to inject into the surface of the protected metals, forming effective impressed current cathodic protection by harvesting mechanical energy or wind energy. This smart device has potential applications for protecting metals from corrosion in daily life, industrial production and ocean exploration by harvesting the energies in the ambient environment. PMID:28451105

  19. Cathodic degradation of antibiotics: characterization and pathway analysis.

    PubMed

    Kong, Deyong; Liang, Bin; Yun, Hui; Cheng, Haoyi; Ma, Jincai; Cui, Minhua; Wang, Aijie; Ren, Nanqi

    2015-04-01

    Antibiotics in wastewaters must be degraded to eliminate their antibacterial activity before discharging into the environment. A cathode can provide continuous electrons for the degradation of refractory pollutants, however the cathodic degradation feasibility, efficiency and pathway for different kinds of antibiotics is poorly understood. Here, we investigated the degradation of four antibiotics, namely nitrofurazone (NFZ), metronidazole (MNZ), chloramphenicol (CAP), and florfenicol (FLO) by a poised cathode in a dual chamber electrochemical reactor. The cyclic voltammetry preliminarily proved the feasibility of the cathodic degradation of these antibiotics. The cathodic reducibility of these antibiotics followed the order of NFZ > MNZ > CAP > FLO. A decreased phosphate buffered solution (PBS) concentration as low as 2 mM or utilization of NaCl buffer solution as catholyte had significant influence on antibiotics degradation rate and efficiency for CAP and FLO but not for NFZ and MNZ. PBS could be replaced by Na2CO3-NaHCO3 buffer solution as catholyte for the degradation of these antibiotics. Reductive dechlorination of CAP proceeded only after the reduction of the nitro group to aromatic amine. The composition of the degradation products depended on the cathode potential except for MNZ. The cathodic degradation process could eliminate the antibacterial activity of these antibiotics. The current study suggests that the electrochemical reduction could serve as a potential pretreatment or advanced treatment unit for the treatment of antibiotics containing wastewaters.

  20. The cathode plasma simulation

    NASA Astrophysics Data System (ADS)

    Suksila, Thada

    Since its invention at the University of Stuttgart, Germany in the mid-1960, scientists have been trying to understand and explain the mechanism of the plasma interaction inside the magnetoplasmadynamics (MPD) thruster. Because this thruster creates a larger level of efficiency than combustion thrusters, this MPD thruster is the primary cadidate thruster for a long duration (planetary) spacecraft. However, the complexity of this thruster make it difficult to fully understand the plasma interaction in an MPD thruster while operating the device. That is, there is a great deal of physics involved: the fluid dynamics, the electromagnetics, the plasma dynamics, and the thermodynamics. All of these physics must be included when an MPD thruster operates. In recent years, a computer simulation helped scientists to simulate the experiments by programing the physics theories and comparing the simulation results with the experimental data. Many MPD thruster simulations have been conducted: E. Niewood et al.[5], C. K. J. Hulston et al.[6], K. D. Goodfellow[3], J Rossignol et al.[7]. All of these MPD computer simulations helped the scientists to see how quickly the system responds to the new design parameters. For this work, a 1D MPD thruster simulation was developed to find the voltage drop between the cathode and the plasma regions. Also, the properties such as thermal conductivity, electrical conductivity and heat capacity are temperature and pressure dependent. These two conductivity and heat capacity are usually definded as constant values in many other models. However, this 1D and 2D cylindrical symmetry MPD thruster simulations include both temperature and pressure effects to the electrical, thermal conductivities and heat capacity values interpolated from W. F. Ahtye [4]. Eventhough, the pressure effect is also significant; however, in this study the pressure at 66 Pa was set as a baseline. The 1D MPD thruster simulation includes the sheath region, which is the

  1. Depression cathode structure for cathode ray tubes having surface smoothness and method for producing same

    SciTech Connect

    Rychlewski, T.V.

    1984-10-23

    Depression cathode structures for cathode ray tubes are produced by dispensing liquid cathode material into the depression of a metallic supporting substrate, removing excess cathode material by passing a doctor blade across the substrate surface and over the depression, and drying the cathode layer to a substantially immobile state. The cathode layer may optionally be further shaped prior to substantially complete drying thereof.

  2. Protective Factors Interrupting the Continuity from School Bullying to Later Internalizing and Externalizing Problems: A Systematic Review of Prospective Longitudinal Studies

    ERIC Educational Resources Information Center

    Ttofi, Maria M.; Bowes, Lucy; Farrington, David P.; Lösel, Friedrich

    2014-01-01

    A systematic review is presented, based on prospective longitudinal studies, on protective factors that interrupt the continuity from bullying perpetration at school to externalizing problem behaviors later in life; and from bullying victimization to later internalizing problems. Some common factors were established, which seem to interrupt the…

  3. Protective Factors Interrupting the Continuity from School Bullying to Later Internalizing and Externalizing Problems: A Systematic Review of Prospective Longitudinal Studies

    ERIC Educational Resources Information Center

    Ttofi, Maria M.; Bowes, Lucy; Farrington, David P.; Lösel, Friedrich

    2014-01-01

    A systematic review is presented, based on prospective longitudinal studies, on protective factors that interrupt the continuity from bullying perpetration at school to externalizing problem behaviors later in life; and from bullying victimization to later internalizing problems. Some common factors were established, which seem to interrupt the…

  4. Is overprotection of the sulfur cathode good for Li-S batteries?

    PubMed

    Gao, Tian; Shao, Jie; Li, Xingxing; Zhu, Guobin; Lu, Qiujian; Han, Yuyao; Qu, Qunting; Zheng, Honghe

    2015-08-11

    How to restrain the dissolution of polysulfides from the sulfur cathode is the current research focus of Li-S batteries. Here, we find that moderate dissolution of polysulfides is of great importance for high-efficiency and stable discharge/charge cycling. Both overprotection and inadequate protection of the sulfur cathode are unfavorable for the cycling of Li-S batteries.

  5. Titanium diaphragm makes excellent amplitron cathode support

    NASA Technical Reports Server (NTRS)

    Teich, W. W.

    1965-01-01

    Cathode support structure designed around a titanium diaphragm prevents radial misalignment between the cathode and anode in amplitrons. The titanium exhibits low thermal conductivity, tolerates lateral thermal expansion of the cathode, and is a poor primary and secondary emission medium.

  6. Triservice/NASA cathode life test facility

    NASA Astrophysics Data System (ADS)

    Windes, D.; Dutkowski, J.; Kaiser, R.; Justice, R.

    1999-05-01

    Since December 1992, Naval Surface Warfare Center-Crane Division (NSWCCD) has logged over 1,318,000 h of cathode life testing on 6 different cathode systems in the Triservice/NASA Cathode Life Test Facility. These include two types of reservoir cathodes designated as MK (Siemens), and RV (CPI, formerly Varian), and impregnated matrix cathodes designated M type (manufactured by Semicon and Hughes), TM (Transition Metal cathodes-CPI) and MMM (Mixed Metal Matrix cathodes-CPI). This paper will present results of the cathode life testing at this facility.

  7. Hot hollow cathode gun assembly

    DOEpatents

    Zeren, J.D.

    1983-11-22

    A hot hollow cathode deposition gun assembly includes a hollow body having a cylindrical outer surface and an end plate for holding an adjustable heat sink, the hot hollow cathode gun, two magnets for steering the plasma from the gun into a crucible on the heat sink, and a shutter for selectively covering and uncovering the crucible.

  8. Cheaper Hydride-Forming Cathodes

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Blue, Gary

    1990-01-01

    Hydride-forming cathodes for electrochemical experiments made of materials or combinations of materials cheaper and more abundant than pure palladium, according to proposal. Concept prompted by needs of experimenters in now-discredited concept of electrochemical nuclear fusion, cathodes useful in other electrochemical applications involving generation or storage of hydrogen, deuterium, or tritium.

  9. Virtual cathode microwave devices -- Basics

    SciTech Connect

    Thode, L.E.; Snell, C.M.

    1991-01-01

    Unlike a conventional microwave tube, a virtual-cathode device operates above the space-charge limit where the depth of the space-charge potential can cause electron reflection. The region associated with this electron reflection is referred to as a virtual cathode. Microwaves can be generated through oscillations in the position of the virtual cathode and through the bunching of electrons trapped in a potential well between the real and virtual cathodes. These two mechanisms are competitive. There are three basic classes of virtual cathode devices: (1) reflex triode; (2) reditron and side-shoot vircator; and (3) reflex diode or vircator. The reflex diode is the highest power virtual-cathode device. For the reflex diode the energy exchange between the beam and electromagnetic wave occurs in both the axial and radial directions. In some designs the oscillating-virtual-cathode frequency exceeds the reflexing-electron frequency exceeds the oscillating-virtual-cathode frequency. For the flex diode a periodic disruption in magnetic insulation can modulate the high- frequency microwave power. Overall, particle-in-cell simulation predictions and axial reflex diode experiments are in good agreement. Although frequency stability and phase locking of the reflex diode have been demonstrated, little progress has been made in efficiency enhancement. 58 refs., 11 figs.

  10. Cathodic hydrodimerization of nitroolefins

    PubMed Central

    Weßling, Michael

    2015-01-01

    Summary Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C–C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a ß,ß-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products. PMID:26199673

  11. Cathodic hydrodimerization of nitroolefins.

    PubMed

    Weßling, Michael; Schäfer, Hans J

    2015-01-01

    Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C-C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a ß,ß-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products.

  12. Apparatus and method for treating a cathode material provided on a thin-film substrate

    DOEpatents

    Hanson, Eric J.; Kooyer, Richard L.

    2003-01-01

    An apparatus and method for treating a cathode material provided on a surface of a continuous thin-film substrate and a treated thin-film cathode having increased smoothness are disclosed. A web of untreated cathode material is moved between a feed mechanism and a take-up mechanism, and passed through a treatment station. The web of cathode material typically includes areas having surface defects, such as prominences extending from the surface of the cathode material. The surface of the cathode material is treated with an abrasive material to reduce the height of the prominences so as to increase an 85 degree gloss value of the cathode material surface by at least approximately 10. The web of cathode material may be subjected to a subsequent abrasive treatment at the same or other treatment station. Burnishing or lapping film is employed at a treatment station to process the cathode material. An abrasive roller may alternatively be used to process the web of cathode material. The apparatus and method of the present invention may also be employed to treat the surface of a lithium anode foil so as to cleanse and reduce the roughness of the anode foil surface.

  13. Apparatus and method for treating a cathode material provided on a thin-film substrate

    SciTech Connect

    Hanson, Eric J.; Kooyer, Richard L.

    2001-01-01

    An apparatus and method for treating a cathode material provided on a surface of a continuous thin-film substrate and a treated thin-film cathode having increased smoothness are disclosed. A web of untreated cathode material is moved between a feed mechanism and a take-up mechanism, and passed through a treatment station. The web of cathode material typically includes areas having surface defects, such as prominences extending from the surface of the cathode material. The surface of the cathode material is treated with an abrasive material to reduce the height of the prominences so as to increase an 85 degree gloss value of the cathode material surface by at least approximately 10. The web of cathode material may be subjected to a subsequent abrasive treatment at the same or other treatment station. Burnishing or lapping film is employed at a treatment station to process the cathode material. An abrasive roller may alternatively be used to process the web of cathode material. The apparatus and method of the present invention may also be employed to treat the surface of a lithium anode foil so as to cleanse and reduce the roughness of the anode foil surface.

  14. One Month Continuous Operation of Organic p-i-n Solar Cells Covered with a Zinc Oxide Protection Layer

    NASA Astrophysics Data System (ADS)

    Hiramoto, Masahiro; Shiokawa, Hiroki

    2010-08-01

    Organic p-i-n solar cells comprising metal-free phthalocyanine and fullerene, which was covered with an aluminum doped zinc oxide protection layer, were successfully operated for 42 days under white light (100 mW cm-2) irradiation. Decreases in the short-circuit photocurrent density and conversion efficiency during this period were just 3 and 5%, respectively. These results suggest that organic solar cells possess sufficient potential for practical long-term durability.

  15. Hollow Cathode With Multiple Radial Orifices

    NASA Technical Reports Server (NTRS)

    Brophy, John R.

    1992-01-01

    Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

  16. Magnetic-cusp, cathodic-arc source

    DOEpatents

    Falabella, Steven

    1995-01-01

    A magnetic-cusp for a cathodic-arc source wherein the arc is confined to the desired cathode surface, provides a current path for electrons from the cathode to the anode, and utilizes electric and magnetic fields to guide ions from the cathode to a point of use, such as substrates to be coated. The magnetic-cusp insures arc stability by an easy magnetic path from anode to cathode, while the straight-through arrangement leads to high ion transmission.

  17. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, Gordon E.

    1998-01-01

    A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

  18. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, Gordon E.

    1998-01-01

    A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

  19. Cold cathode vacuum gauging system

    DOEpatents

    Denny, Edward C.

    2004-03-09

    A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

  20. Liquid cathode primary batteries

    NASA Astrophysics Data System (ADS)

    Schlaikjer, Carl R.

    1985-03-01

    Lithium/liquid cathode/carbon primary batteries offer from 3 to 6 times the volumetric energy density of zinc/alkaline manganese cells, improved stability during elevated temperature storage, satisfactory operation at temperatures from -40 to +150 °C, and efficient discharge at moderate rates. he lithium/sulfur dioxide cell is the most efficient system at temperatures below 0 °C. Although chemical reactions leading to electrolyte degradation and lithium corrosion are known, the rates of these reactions are slow. While the normal temperature cell reaction produces lithium dithionite, discharge at 60 °C leads to a reduction in capacity due to side reactions involving sulfur dioxide and discharge intermediates. Lithium/thionyl chloride and lithium/sulfuryl chloride cells have the highest practical gravimetric and volumetric energy densities when compared with aqueous and most other nonaqueous systems. For thionyl chloride, discharge proceeds through a series of intermediates to sulfur, sulfur dioxide and lithium chloride. Catalysis, leading to improved rate capability and capacity, has been achieved. The causes of rapid reactions leading to thermal runaway are thought to be chemical in nature. Lithium/sulfuryl chloride cells, which produce sulfur dioxide and lithium chloride on discharge, experience more extensive anode corrosion. An inorganic cosolvent and suitable salt are capable of alleviating this corrosion. Calcium/oxyhalide cells have been studied because of their promise of increased safety without substantial sacrifice of energy density relative to lithium cells. Anode corrosion, particularly during discharge, has delayed practical development.

  1. Electropositive surface layer MPD thruster cathodes

    SciTech Connect

    Chamberlain, F.R.; Kelly, A.J.; Jahn, R.G.

    1989-01-01

    Lithium and barium oxide have been used to generate electropositive surface layers on tungsten cathodes in low power steady state MPD thruster experiments. The electropositive surface layer decreases the cathode work function, resulting in substantial reductions in the steady state cathode operating temperature and erosion rate. Cathode temperature is reduced by 300 degrees with a lithium surface layer and by 800 degrees with a barium oxide surface layer at a 500 ampere thruster current level. These temperature reductions substantially reduce the calculated steady state evaporative erosion rate of the cathode by factors of 20 and 10,000 respectively. Cold cathode startup erosion is also reduced dramatically. The surface melting and arc cratering that is characteristic of pure tungsten cathodes does not occur with an electropositive surface layer cathode. In addition to reducing cathode erosion, the use of these materials increases thruster efficiency. 12 refs.

  2. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a one-time... forth as follows: § 261.41 Notification and Recordkeeping for Used, Intact Cathode Ray Tubes...

  3. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment... WASTE Exclusions/Exemptions § 261.40 Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet...

  4. Effect of La0.1Sr0.9Co0.5Mn0.5O3-δ protective coating layer on the performance of La0.6Sr0.4Co0.8Fe0.2O3-δ solid oxide fuel cell cathode

    NASA Astrophysics Data System (ADS)

    Chou, Ping-Yi; Ciou, Chun-Jing; Lee, Yu-Chen; Hung, I.-Ming

    2012-01-01

    This study investigates the interface reactivity between La0.1Sr0.9Co0.5Mn0.5O3-δ (LSCM) protective coating layer and Crofer22H interconnects. Additionally, we report the mechanism of Cr poisoning of the La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) cathode's electrochemical properties. The phase, chemical composition, and element distribution of compounds formed at the LSCM-Crofer22H interface are analyzed by X-ray diffraction (XRD) and electron dispersive microscopy (EDS). After heat treatment at 800 °C for 100 h, the LSCM/Crofer22H sample contains SrCrO3, a compound with good conductivity; the area specific resistance (ASR) for the LSCM/Crofer22H interconnect is approximately 17-40 mΩ cm2. We found that the amount of (Mn0.98Fe0.02)(Mn0.02Fe0.48Cr1.5)O4, Cr3O4, and (Fe,Cr)2O3 oxides form in LSCF/LSCM/Crofer22H is significantly less than that in LSCF/Crofer22H. LSCF conductivity after heating at 800 °C for 100 h, is notably higher when in contact with LSCM/Crofer22H than it is when in contact with Crofer22H. These results demonstrate that the LSCM protective coating prevents LSCF cathode poisoning by Cr evaporated from the Corfer22H interconnects.

  5. Fundamental Investigations and Rational Design of Durable High-Performance SOFC Cathodes

    SciTech Connect

    Chen, Yu; Ding, Dong; Wei, Tao; Liu, Meilin

    2016-03-31

    cathodes as well as the cathode/electrolyte interfaces under realistic operating conditions has been studied. It is found that SrO readily segregated/enriched on the LSCF surface. More severe contamination conditions cause more SrO on surface. Novel catalyst coatings through particle depositions (PrOx) or continuous thin films (PNM) were successfully developed to improve the activity and stability of LSCF cathodes. Finally, we have demonstrated enhanced activity and stability of LSCF cathodes over longer periods of time in homemade and commercially available cells by an optimized PNM (dense film and particles) infiltration process, under clean air and realistic operating conditions (3% H2O, 5% CO2 and direct Crofer contact). Both performance and durability of single cells with PNM coating has been enhanced compared with those without coating. Raman analysis of cathodes surface indicated that the intensity of SrCrO4 was significantly decreased.

  6. Hollow cathodes for arcjet thrusters

    NASA Technical Reports Server (NTRS)

    Luebben, Craig R.; Wilbur, Paul J.

    1987-01-01

    In an attempt to prevent exterior spot emission, hollow cathode bodies and orifice plates were constructed from boron nitride which is an electrical insulator, but the orifice plates melted and/or eroded at high interelectrode pressures. The most suitable hollow cathodes tested included a refractory metal orifice plate in a boron nitride body, with the insert insulated electrically from the orifice plate. In addition, the hollow cathode interior was evacuated to assure a low pressure at the insert surface, thus promoting diffuse electron emission. At high interelectrode pressures, the electrons tended to flow through the orifice plate rather than through the orifice, which could result in overheating of the orifice plate. Using a carefully aligned centerline anode, electron flow through the orifice could be sustained at interelectrode pressures up to 500 torr - but the current flow path still occasionally jumped from the orifice to the orifice plate. Based on these tests, it appears that a hollow cathode would operate most effectively at pressures in the arcjet regime with a refractory, chemically stable, and electrically insulating cathode body and orifice plate.

  7. Protection of Penaeus monodon against white spot syndrome by continuous oral administration of a low concentration of Bacillus subtilis spores expressing the VP28 antigen.

    PubMed

    Pham, K-C; Tran, H T T; Van Doan, C; Le, P H; Van Nguyen, A T; Nguyen, H A; Hong, H A; Cutting, S M; Phan, T-N

    2017-03-01

    In this study, Bacillus subtilis spores expressing a chimeric protein, CotB-VP28, were used as a probiotic vaccine to protect black tiger shrimps (Penaeus monodon) against white spot syndrome virus (WSSV) infection. Oral administration of pellets coated with CotB-VP28 spores (at ≥1 × 10(9 ) CFU per g pellet) to shrimps induced immune-relating phenoloxydase activity (PO) in shrimps after 14 days of feeding (prior challenge) and at day 3 post challenge (1·26 and 1·70 fold increase respectively). A 75% protection rate was obtained by continuous feeding of the spore-coated pellets at ≥1 × 10(9 ) CFU per g for 14 days prior to WSSV challenge and during all the postchallenge period. Even when the amount of CotB-VP28 spores in feed pellets was reduced down to ≥5 × 10(7)  CFU per g and ≥1 × 10(6)  CFU per g, relatively high protection rates of 70 and 67·5%, respectively, were still obtained. By contrast, feeding pellets without spores (untreated group) and with naked spores (PY79 group) at ≥1 × 10(9)  CFU per g could not protect shrimps against WSSV. These data suggest that supplementation of CotB-VP28 spores at low dose of ≥1 × 10(6)  CFU per g could be effective as a prophylactic treatment of WSS for black tiger shrimps. This study reports the protective efficacy of Bacillus subtilis CotB-VP28 spores on black tiger shrimps (Penaeus monodon) against white spot syndrome virus infection. Oral administration of pellets coated with CotB-VP28 spores (≥1 × 10(9 ) CFU per g) conferred 75% protection after white spot syndrome virus challenge. Even after reducing CotB-VP28 spores in feed pellets to ≥1 × 10(6)  CFU per g, 67·5% protections was still obtained. These data indicate that supplementation of CotB-VP28 spores at a low dose of ≥1 × 10(6)  CFU per g could be effective in prophylaxis against white spot syndrome in black tiger shrimps. © 2016 The Society for Applied Microbiology.

  8. In situ cathodic activation of V-incorporated NixSy nanowires for enhanced hydrogen evolution.

    PubMed

    Shang, Xiao; Yan, Kai-Li; Rao, Yi; Dong, Bin; Chi, Jing-Qi; Liu, Yan-Ru; Li, Xiao; Chai, Yong-Ming; Liu, Chen-Guang

    2017-08-31

    In situ cathodic activation (ISCA) of V-incorporated NixSy nanowires supported on nickel foam (VS/NixSy/NF) can be realized in an alkaline hydrogen evolution reaction (HER) process, which provides not only clearly enhanced activity but also ultrahigh stability for HER. The ISCA process is continuous linear sweep voltammetry (LSV) on VS/NixSy/NF as a cathodic electrode with gradually enhanced HER activity. The activated VS/NixSy/NF (A-VS/NixSy/NF) demonstrates enhanced HER activity with an overpotential of 125 mV to drive 10 mA cm(-2), which is much lower than that of other samples. It may be predicted that the ISCA-derived amorphous VOOH film covering on A-VS/NixSy/NF accelerates the HER process, and NiOOH may protect active sites from decaying, leading to excellent activity and structural stability. However, for single metal sulfides, the ISCA process of nickel or vanadium sulfides is not available, implying that the synergistic effect between Ni and V of VS/NixSy/NF may be the key to drive ISCA in alkaline HER. In addition, its ultra-high stability confirms that the stable active sites and nanostructures of A-VS/NixSy/NF are derived from ISCA. Therefore, the ISCA of V-incorporated transition metal sulfides in the alkaline HER process may be a facile and promising method to obtain efficient electrocatalysts.

  9. High-current-density, high brightness cathodes for free electron laser applications

    SciTech Connect

    Green, M.C. . Palo Alto Microwave Tube Div.)

    1987-06-01

    This report discusses the following topics: brightness and emittance of electron beams and cathodes; general requirements for cathodes in high brightness electron guns; candidate cathode types; plasma and field emission cathodes; true field emission cathodes; oxide cathodes; lanthanum hexaborides cathodes; laser driven thermionic cathodes; laser driven photocathodes; impregnated porous tungsten dispenser cathodes; and choice of best performing cathode types.

  10. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, G.E.

    1998-03-10

    A cold cathode vacuum discharge tube, and method for making same, are disclosed with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 15 figs.

  11. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, G.E.

    1998-04-14

    A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by chemical vapor deposition (CVD) or diamond-like carbon (DLC) deposition are disclosed. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 14 figs.

  12. Mechanistic Enhancement of SOFC Cathode Durability

    SciTech Connect

    Wachsman, Eric

    2016-02-01

    Durability of solid oxide fuel cells (SOFC) under “real world” conditions is an issue for commercial deployment. In particular cathode exposure to moisture, CO2, Cr vapor (from interconnects and BOP), and particulates results in long-term performance degradation issues. Here, we have conducted a multi-faceted fundamental investigation of the effect of these contaminants on cathode performance degradation mechanisms in order to establish cathode composition/structures and operational conditions to enhance cathode durability.

  13. Physical Processes in Hollow Cathode Discharge

    DTIC Science & Technology

    1989-12-01

    BUIT FiLE COPY NAVAL POSTGRADUATE SCHOOL Monterey, California 0DTIC x ,, , ’ AELECTEi<AU 17U THESIS L . PHYSICAL PROCESSES IN HOLLOW CATHODE...IPROJECT ITASK IWORK UNIT ELEMENT NO. NO. NO ACCESSION NO 11. TITLE (Include Security Classification) Physical Processes in Hollow Cathode Discharge 12...number) The hollow cathode is an effective source of dense, low energy plasma. Hollow cathodes find use in ion beam sources for laboratory and space

  14. Measured cathode fall characteristics depending on the diameter of a hydrogen hollow cathode discharge

    NASA Astrophysics Data System (ADS)

    Gonzalez-Fernandez, V.; Grützmacher, K.; Steiger, A.; Pérez, C.; de la Rosa, M. I.

    2017-10-01

    In this work, Doppler-free two photon optogalvanic spectroscopy is used to measure the electric field strength in the cathode fall region of a hollow cathode discharge, operated in pure hydrogen, via the Stark splitting of the 2S level of atomic hydrogen. The cathode fall characteristics are analysed for various pressures and in a wide range of discharge currents. Tungsten is used as the cathode material, because it allows for reliable measurements in a fairly wide range of discharge conditions and because of its minimal sputtering. Two cathode diameters (10 mm and 15 mm) are used to study the dependence of the cathode fall on discharge geometry. The measurements reveal that the cathode fall characteristics are quite independent on the cathode diameter for equal cathode current density; hence the measurements can be used to test one dimensional modelling of the cathode fall region for low pressure hydrogen discharges using e.g. plane parallel electrodes.

  15. Novel Cathodes Prepared by Impregnation Procedures

    SciTech Connect

    Eduardo Paz

    2006-09-30

    (1) We showed that similar results were obtained when using various LSM precursors to produce LSM-YSZ cathodes. (2) We showed that enhanced performance could be achieved by adding LSCo to LSMYSZ cathodes. (3) We have preliminary results showing that there is a slow deactivation with LSFYSZ cathodes.

  16. Remote control for anode-cathode adjustment

    DOEpatents

    Roose, Lars D.

    1991-01-01

    An apparatus for remotely adjusting the anode-cathode gap in a pulse power machine has an electric motor located within a hollow cathode inside the vacuum chamber of the pulse power machine. Input information for controlling the motor for adjusting the anode-cathode gap is fed into the apparatus using optical waveguides. The motor, controlled by the input information, drives a worm gear that moves a cathode tip. When the motor drives in one rotational direction, the cathode is moved toward the anode and the size of the anode-cathode gap is diminished. When the motor drives in the other direction, the cathode is moved away from the anode and the size of the anode-cathode gap is increased. The motor is powered by batteries housed in the hollow cathode. The batteries may be rechargeable, and they may be recharged by a photovoltaic cell in combination with an optical waveguide that receives recharging energy from outside the hollow cathode. Alternatively, the anode-cathode gap can be remotely adjusted by a manually-turned handle connected to mechanical linkage which is connected to a jack assembly. The jack assembly converts rotational motion of the handle and mechanical linkage to linear motion of the cathode moving toward or away from the anode.

  17. Dual-Cathode Electron-Beam Source

    NASA Technical Reports Server (NTRS)

    Bradley, James G.; Conley, Joseph M.; Wittry, David B.

    1988-01-01

    Beam from either cathode electromagnetically aligned with exit port. Electron beam from either of two cathodes deflected by magnetic and electric fields to central axis. Mechanical alignment of beam easy because cathode axes, anode apertures, and electron trajectories coplanar. Applications where uninterrupted service needed: scanning electron microscopes, transmission electron microscopes, electron-beam lithography equipment, Auger instruments, and microfocused x-ray sources.

  18. Design, construction and long life endurance testing of cathode assemblies for use in microwave high-power transmitting tubes

    NASA Technical Reports Server (NTRS)

    Batra, R.; Marino, D.

    1986-01-01

    The cathode life test program sponsored by NASA Lewis Research Center at Watkins-Johnson Company has been in continuous operation since 1972. Its primary objective has been to evaluate the long life capability of barium dispenser cathodes to produce emission current densities of 2 A sq. cm. or more in an operational environment simulating that of a highpower microwave tube. The life test vehicles were equipped with convergent flow electron guns, drift space tubes with solenoid magnets for electron beam confinement and water-cooled depressed collectors. A variety of cathode types has been tested, including GE Tungstate, Litton Impregnated, Philips Type B and M, Semicon types S and M, and Spectra-Mat Type M. Recent emphasis has been on monitoring the performance of Philips Type M cathodes at 2 A sq. cm. and Sprectra-Mat and Semicon Type M cathodes at 4 A sq. cm. These cathodes have been operated at a constant current of 616 mA and a cathode anode voltage on the order of 10 kV. Cathode temperatures were maintained at 1010 C true as measured from black body holes in the backs of the cathodes. This report presents results of the cathode life test program from July l982 through April l986. The results include hours of operation and performance data in the form of normalized emission current density versus temperature curves (Miram plots).

  19. Design, construction and long life endurance testing of cathode assemblies for use in microwave high-power transmitting tubes

    NASA Astrophysics Data System (ADS)

    Batra, R.; Marino, D.

    1986-09-01

    The cathode life test program sponsored by NASA Lewis Research Center at Watkins-Johnson Company has been in continuous operation since 1972. Its primary objective has been to evaluate the long life capability of barium dispenser cathodes to produce emission current densities of 2 A sq. cm. or more in an operational environment simulating that of a highpower microwave tube. The life test vehicles were equipped with convergent flow electron guns, drift space tubes with solenoid magnets for electron beam confinement and water-cooled depressed collectors. A variety of cathode types has been tested, including GE Tungstate, Litton Impregnated, Philips Type B and M, Semicon types S and M, and Spectra-Mat Type M. Recent emphasis has been on monitoring the performance of Philips Type M cathodes at 2 A sq. cm. and Sprectra-Mat and Semicon Type M cathodes at 4 A sq. cm. These cathodes have been operated at a constant current of 616 mA and a cathode anode voltage on the order of 10 kV. Cathode temperatures were maintained at 1010 C true as measured from black body holes in the backs of the cathodes. This report presents results of the cathode life test program from July l982 through April l986. The results include hours of operation and performance data in the form of normalized emission current density versus temperature curves (Miram plots).

  20. Cathode for molten salt batteries

    DOEpatents

    Mamantov, Gleb; Marassi, Roberto

    1977-01-01

    A molten salt electrochemical system for battery applications comprises tetravalent sulfur as the active cathode material with a molten chloroaluminate solvent comprising a mixture of AlCl.sub.3 and MCl having a molar ratio of AlCl.sub.3 /MCl from greater than 50.0/50.0 to 80/20.

  1. Anion-redox nanolithia cathodes for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Zhi; Kushima, Akihiro; Yin, Zongyou; Qi, Lu; Amine, Khalil; Lu, Jun; Li, Ju

    2016-08-01

    The development of lithium-air batteries is plagued by a high potential gap (>1.2 V) between charge and discharge, and poor cyclability due to the drastic phase change of O2 (gas) and Ox- (condensed phase) at the cathode during battery operations. Here we report a cathode consisting of nanoscale amorphous lithia (nanolithia) confined in a cobalt oxide, enabling charge/discharge between solid Li2O/Li2O2/LiO2 without any gas evolution. The cathode has a theoretical capacity of 1,341 Ah kg-1, a mass density exceeding 2.2 g cm-3, and a practical discharge capacity of 587 Ah kg-1 at 2.55 V versus Li/Li+. It also displays stable cycling performance (only 1.8% loss after 130 cycles in lithium-matched full-cell tests against Li4Ti5O12 anode), as well as a round-trip overpotential of only 0.24 V. Interestingly, the cathode is automatically protected from O2 gas release and overcharging through the shuttling of self-generated radical species soluble in the carbonate electrolyte.

  2. Antitumor protection from the murine T-cell leukemia/lymphoma EL4 by the continuous subcutaneous coadministration of recombinant macrophage-colony stimulating factor and interleukin-2.

    PubMed

    Vallera, D A; Taylor, P A; Aukerman, S L; Blazar, B R

    1993-09-15

    Combined continuous s.c. coadministration of macrophage-colony stimulating factor (M-CSF) plus interleukin-2 (IL-2) by osmotic pump protected mice given i.v. injections of a lethal dose of EL4 T-cell leukemia/lymphoma. Antitumor protection was significantly greater than that afforded by treatment with either cytokine alone. Since neither IL-2 receptors nor M-CSF receptors were expressed on EL4, the antitumor effect was likely attributed to murine effector cells. To determine how M-CSF+IL-2 provided this effect, we performed immunophenotypic and functional analyses as well as in vivo depletion studies of putative antitumor effector cells. Splenic phenotyping experiments revealed that the highest levels of macrophages and natural killer cells were observed in mice given the cytokine combination rather than either M-CSF or IL-2 alone. In vivo depletion of natural killer cells ablated the antitumor protective effect of M-CSF and IL-2. T-cells were also important for M-CSF+IL-2 efficacy, since adult thymectomy/T-cell depletion significantly inhibited the ability of cytokine coadministration to protect against EL4. Coadministration of the 2 cytokines significantly elevated in vivo levels of CD3+CD4+, CD3+CD8+, CD3+NK1.1+ T-cells, and CD3+CD25+ (activated) T-cells, and elevated anti-EL4 cytotoxic T-cell activity measured in vitro. Although WBC counts and fluorescence-activated cell sorter studies showed that M-CSF+IL-2 treatment significantly elevated neutrophils, s.c. delivery of granulocyte-colony stimulating factor at doses sufficient to induce neutrophilia was unable to confer anti-EL4 protection. These studies indicate that macrophages, T-cells, and natural killer cells are all important in the M-CSF+IL-2 anti-EL4 response. The superior antitumor effect of this cytokine combination along with the ability of M-CSF to diminish the toxicity of IL-2 in this model suggests that further investigations into the clinical potential of this combination treatment are warranted.

  3. High-emission cold cathode

    DOEpatents

    Mancebo, L.

    1974-01-29

    A field-emission cathode having a multitude of field emission points for emitting a copious stream of electrons when subjected to a high field is described. The cathode is constructed by compressing a multitude of tungsten strips alternately arranged with molybdenum strips and copper ribbons or compressing alternately arranged copper plated tungsten and molybdenum strips, heating the arrangement to braze the tungsten and molybdenum strips together with the copper, machining and grinding the exposed strip edges of one side of the brazed arrangement to obtain a precisely planar surface, etching a portion of the molybdenum and copper to leave the edges of the tungsten strips protruding for electron emission, and subjecting the protruding edges of the tungsten strips to a high electric field to degas and roughen the surface to pnovide a large number of emitting points. The resulting structure is particularly useful as a cathode in a transversely excited gaseous laser where the cathode is mounted in a vacuum chamber for emitting electrons under the influence of a high electric field between the cathode and an extractor grid. The electrons pass through the extractor grid, a thin window in the wall of the laser chamber and into the laser chamber which is filled with a gaseous mixture of helium, nitrogen, and carbon dioxide. A second grid is mounted on the gaseous side of the window. The electrons pass into the laser chamber under the influence of a second electric field between the second grid and an anode in the laser chamber to raise selected gas atoms of the gaseous mixture to appropriately excited states so that a subsequent coherent light beam passing through the mixture transversely to the electron stream through windows in opposite ends of the laser chamber stimulates the excited atoms to amplify the beam. (Official Gazette)

  4. Cathode for aluminum producing electrolytic cell

    DOEpatents

    Brown, Craig W.

    2004-04-13

    A method of producing aluminum in an electrolytic cell comprising the steps of providing an anode in a cell, preferably a non-reactive anode, and also providing a cathode in the cell, the cathode comprised of a base material having low electrical conductivity reactive with molten aluminum to provide a highly electrically conductive layer on the base material. Electric current is passed from the anode to the cathode and alumina is reduced and aluminum is deposited at the cathode. The cathode base material is selected from boron carbide, and zirconium oxide.

  5. Cathodes for molten-salt batteries

    NASA Technical Reports Server (NTRS)

    Argade, Shyam D.

    1993-01-01

    Viewgraphs of the discussion on cathodes for molten-salt batteries are presented. For the cathode reactions in molten-salt cells, chlorine-based and sulfur-based cathodes reactants have relatively high exchange current densities. Sulfur-based cathodes, metal sulfides, and disulfides have been extensively investigated. Primary thermal batteries of the Li-alloy/FeS2 variety have been available for a number of years. Chlorine based rechargable cathodes were investigated for the pulse power application. A brief introduction is followed by the experimental aspects of research, and the results obtained. Performance projections to the battery system level are discussed and the presentation is summarized with conclusions.

  6. Magnetic-cusp, cathodic-arc source

    DOEpatents

    Falabella, S.

    1995-11-21

    A magnetic-cusp for a cathodic-arc source wherein the arc is confined to the desired cathode surface, provides a current path for electrons from the cathode to the anode, and utilizes electric and magnetic fields to guide ions from the cathode to a point of use, such as substrates to be coated. The magnetic-cusp insures arc stability by an easy magnetic path from anode to cathode, while the straight-through arrangement leads to high ion transmission. 3 figs.

  7. Hydrogen production in a microbial electrolysis cell with nickel-based gas diffusion cathodes

    NASA Astrophysics Data System (ADS)

    Manuel, M.-F.; Neburchilov, V.; Wang, H.; Guiot, S. R.; Tartakovsky, B.

    Gas diffusion cathodes with Ni alloy and Ni catalysts manufactured by chemical deposition were tested for H 2 production in a microbial electrolysis cell (MEC). In a continuous flow MEC, multi-component cathodes containing Ni, Mo, Cr, and Fe, at a total catalyst load of 1 mg cm -2 on carbon support demonstrated stable H 2 production at rates of 2.8 - 3.7 L LR-1 d-1 with only 5% methane in the gas stream. Furthermore, a Ni-only gas diffusion cathode, with a Ni load of 0.6 mg cm -2, demonstrated a H 2 production rate of 4.1 L LR-1 d-1 . Overall, H 2 production was found to be proportional to the Ni load implying that inexpensive gas diffusion cathodes prepared by chemical deposition of Ni can be successfully used for continuous production of H 2 in a MEC.

  8. Synthesis and Enhanced Corrosion Protection Performance of Reduced Graphene Oxide Nanosheet/ZnAl Layered Double Hydroxide Composite Films by Hydrothermal Continuous Flow Method.

    PubMed

    Luo, Xiaohu; Yuan, Song; Pan, Xinyu; Zhang, Caixia; Du, Shuo; Liu, Yali

    2017-05-31

    Prevention of water, oxygen, and chloride ions contained in hydrotalcite interlayers from diffusing through the layered double hydroxides (LDH) is of crucial importance in corrosion protection. In this work, a hybrid composed of reduced graphene oxide (RGO) nanosheets/Zn(2+)/Al(3+) layered double hydroxide (RGO/ZnAl-LDH) composite films on the surface of 6N01 aluminum (Al) alloy was successfully synthesized by a novel and facile hydrothermal continuous flow method, which enabled direct growth of the composite on the surface of the Al alloy substrate. The structure and morphology of the RGO/ZnAl-LDH composite films were fully characterized. Based on electrochemical measurements in a NaCl solution, the RGO/ZnAl-LDH composite film significantly enhanced the corrosion protection, as compared with the ZnAl-LDH film. The RGO/ZnAl-LDH composite film could maintain an outstanding corrosion resistance after 7 days immersion in a high concentration of NaCl solution (i.e., 5.0 wt %). The enhanced corrosion resistance was attributed to the barrier effect on diffusion of water, oxygen, and chloride ions by the RGO contained in the RGO/ZnAl-LDH composite films.

  9. Improved Cathode Structure for a Direct Methanol Fuel Cell

    NASA Technical Reports Server (NTRS)

    Valdez, Thomas; Narayanan, Sekharipuram

    2005-01-01

    An improved cathode structure on a membrane/electrode assembly has been developed for a direct methanol fuel cell, in a continuing effort to realize practical power systems containing such fuel cells. This cathode structure is intended particularly to afford better cell performance at a low airflow rate. A membrane/electrode assembly of the type for which the improved cathode structure was developed (see Figure 1) is fabricated in a process that includes brush painting and spray coating of catalyst layers onto a polymer-electrolyte membrane and onto gas-diffusion backings that also act as current collectors. The aforementioned layers are then dried and hot-pressed together. When completed, the membrane/electrode assembly contains (1) an anode containing a fine metal black of Pt/Ru alloy, (2) a membrane made of Nafion 117 or equivalent (a perfluorosulfonic acid-based hydrophilic, proton-conducting ion-exchange polymer), (3) a cathode structure (in the present case, the improved cathode structure described below), and (4) the electrically conductive gas-diffusion backing layers, which are made of Toray 060(TradeMark)(or equivalent) carbon paper containing between 5 and 6 weight percent of poly(tetrafluoroethylene). The need for an improved cathode structure arises for the following reasons: In the design and operation of a fuel-cell power system, the airflow rate is a critical parameter that determines the overall efficiency, cell voltage, and power density. It is desirable to operate at a low airflow rate in order to obtain thermal and water balance and to minimize the size and mass of the system. The performances of membrane/electrode assemblies of prior design are limited at low airflow rates. Methanol crossover increases the required airflow rate. Hence, one way to reduce the required airflow rate is to reduce the effect of methanol crossover. Improvement of the cathode structure - in particular, addition of hydrophobic particles to the cathode - has been

  10. MPD thruster performance with cathode heating

    NASA Astrophysics Data System (ADS)

    Andrenucci, M.; Paganucci, F.; La Motta, G.

    1992-07-01

    A gas-fed MPD thruster with a cathode heating system was developed which can bring the cathode to temperatures at which significant thermionic emission is present. The heat is provided by an electrical arc established between the inner surface of the cathode tip and a thoriated tungsten electrode inserted into a blind hole drilled along the cathode axis. A series of preliminary tests intended to verify the proper operation of the device and its possibility to reach temperatures beyond 2000 K at the cathode tip are described. Electrical characteristics and performance (thrust efficiency and specific impulse) obtained with cold electrodes and hot electrodes for 4g/s of Argon are shown, and a comparison between the two thermal configurations is made. The data obtained show that the electrode thermal conditions have a decisive effect on thruster electrical characteristics, instabilities and erosion phenomena. In particular, hot cathode thrust efficiency is substantially higher than cold cathode efficiency.

  11. Invited article: physical and chemical analyses of impregnated cathodes operated in a plasma environment.

    PubMed

    Sengupta, Anita; Kulleck, James; Hill, Norm; Ohlinger, Wayne

    2008-11-01

    Destructive analyses of impregnated-cathode assemblies from an ion thruster life test were performed to characterize erosion and degradation after 30,472 h of operation. Post-test inspection of each cathode included examination of the emitter (insert), orifice plate, cathode tube, heater, anode assembly, insulator, and propellant isolator. The discharge-cathode assembly experienced significant erosion due to ion sputtering from the discharge plasma. The keeper electrode plate was removed and the heater and orifice plate were heavily eroded at the conclusion of the test. Had the test continued, these processes would likely have led to cathode failure. The discharge cathode insert experienced significant tungsten transport and temperature dependent barium oxide depletion within the matrix. Using barium depletion semiempirical relations developed by Palluel and Shroff, it is estimated that 25,000 h of operation remained in the discharge insert at the conclusion of the test. In contrast, the neutralizer insert exhibited significantly less tungsten transport and barium oxide depletion consistent with its lower current operation. The neutralizer was estimated to have 140,000 h of insert life remaining at the conclusion of the test. Neither insert had evidence of tungstate or oxide layer formation, previously known to have impeded cathode ignition and operation in similar long duration hollow-cathode tests. The neutralizer cathode was in excellent condition at the conclusion of the test with the exception of keeper tube erosion from direct plume-ion impingement, a previously underappreciated life-limiting mechanism. The most critical finding from the test was a power dependent deposition process within the neutralizer-cathode orifice. The process manifested at low-power operation and led to the production of energetic ions in the neutralizer plume, a potential life-limiting process for the neutralizer. Subsequent return of the engine and neutralizer operation to full

  12. Nickel-titanium-phosphate cathodes

    DOEpatents

    Belharouak, Ilias; Amine, Khalil

    2008-12-16

    Cathode materials having an improved electronic conductivity allowing for faster kinetics in the electrochemical reaction, as well as higher conductivity to meet the power requirements for many consumer applications, especially at low temperatures. The cathode material comprises a compound from the family of compounds where the basic unit is generally represented by Li.sub.xNi.sub.0.5TiOPO.sub.4. The structure of Li.sub.xNi.sub.0.5TiOPO.sub.4 includes corner sharing octahedra [TiO.sub.6] running along the C-axis. The structure is such that nearly three Li atoms are being inserted in Li.sub.xNi.sub.0.5TiOPO.sub.4. A cell in accordance with the principles of the present invention is rechargable and demonstrates a high capacity of lithium intercalation and fast kinetics.

  13. Filters for cathodic arc plasmas

    DOEpatents

    Anders, Andre; MacGill, Robert A.; Bilek, Marcela M. M.; Brown, Ian G.

    2002-01-01

    Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  14. [Adhesion of sulphate-reducing bacteria to steel under cathode polarization].

    PubMed

    Purish, L M; Koptieva, Zh P; Asaulenko, L H; Kozlova, I P

    2006-01-01

    Adhesion of different (as to their corrosion aggression) strains of sulphate-reducing bacteria to steel has been studied under cathode polarization at various potentials: -800, -900, -1000, -1200 mV. It has been established that cathode polarization differently affects the adhesion of strain of sulphate-reducing bacteria with various aggression to steel. Correlation between the bacterial strains aggression and the number of cells adhered to metal have been noted. The cells of aggressive strains of D. indonensis Indonesia and Desulfovibrio sp. Kiev-10 adhered to metal most actively at cathode depolarization (8.0 x 10(7) and 3.5 x 10(7) cell/cm2, respectively). Nonaggressive strains of bacteria D. desulfuricans Kiev-45 and Desulfobulbus sp. Portsmouth adhered to metal in a less quantity. The data obtained prove that the use of cathode protection without allowance for the microbe factor can lead to intensification of the corrosion process.

  15. Barium-Dispenser Thermionic Cathode

    NASA Technical Reports Server (NTRS)

    Wintucky, Edwin G.; Green, M.; Feinleib, M.

    1989-01-01

    Improved reservoir cathode serves as intense source of electrons required for high-frequency and often high-output-power, linear-beam tubes, for which long operating lifetime important consideration. High emission-current densities obtained through use of emitting surface of relatively-low effective work function and narrow work-function distribution, consisting of coat of W/Os deposited by sputtering. Lower operating temperatures and enhanced electron emission consequently possible.

  16. Theory, Investigation and Stability of Cathode Electrocatalytic Activity

    SciTech Connect

    Ding, Dong; Liu, Mingfei; Lai, Samson; Blinn, Kevin; Liu, Meilin

    2012-09-30

    conditions. This was also confirmed by x-ray analyses. For example, soft x-ray XANES data reveal that Co cations displace the Mn cations as being more favored to be reduced. Variations in the Sr-O in the annealed LSCF Fourier-transformed (FT) EXAFS suggest that some Sr segregation is occurring, but is not present in the annealed LSM-infiltrated LSCF cathode materials. Further, a surface enhanced Raman technique was also developed into to probe and map LSM and LSCF phase on underlying YSZ substrate, enabling us to capture important chemical information of cathode surfaces under practical operating conditions. Electrochemical models for the design of test cells and understanding of mechanism have been developed for the exploration of fundamental properties of electrode materials. Novel catalyst coatings through particle depositions (SDC, SSC, and LCC) or continuous thin films (PSM and PSCM) were successfully developed to improve the activity and stability of LSCF cathodes. Finally, we have demonstrated enhanced activity and stability of LSCF cathodes over longer periods of time in homemade and commercially available cells by an optimized LSM infiltration process. Microstructure examination of the tested cells did not show obvious differences between blank and infiltrated cells, suggesting that the infiltrated LSM may form a coherent film on the LSCF cathodes. There was no significant change in the morphology or microstructure of the LSCF cathode due to the structural similarity of LSCF and LSM. Raman analysis of the tested cells indicated small peaks emerging on the blank cells that correspond to trace amounts of secondary phase formation during operation (e.g., CoO{sub x}). The formation of this secondary phase might be attributed to performance degradation. In contrast, there was no such secondary phase observed in the LSM infiltrated cells, indicating that the LSM modification staved off secondary phase formation and thus improved the stability.

  17. Considerations of the Role of the Cathodic Region in Localized Corrosion

    SciTech Connect

    R.G. Kelly; A. Agarwal; F. Cui; X. Shan; U. Landau; J.H. Payer

    2006-03-17

    The ability of wetted cathodes of limited area to support localized corrosion sites on passive materials exposed to atmospheric conditions was studied computationally. The analysis pertains to conditions where metal surfaces are covered by thin layers of moisture in contrast to conditions of full immersion. The moisture may be a continuous layer or in patches with and without particulate on the surface. These conditions are of interest for the surfaces of the waste packages at the proposed Yucca Mountain Repository where waste packages are supported in air. The cathode capacity was characterized by the total net cathodic current, I{sub net}, which the surface surrounding a localized corrosion site (i.e., a pit or crevice) could supply. The cathode capacity increases with increasing cathode area, but it saturates at finite cathode sizes due to the resistance of the thin electrolyte layer. The magnitude of the capacity depends on the water layer thickness, the solution conductivity, and the electrochemical reaction kinetics. The presence of particulates is treated by considering both volume and surface coverage effects. The limited electrolyte volume under thin film conditions can lead to rapid pH changes which decrease the cathode capacity due to the slower electrochemical kinetics at elevated pH. These effects can make localized corrosion less likely to be sustained.

  18. Life test of a xenon hollow cathode for a space plasma contractor

    NASA Technical Reports Server (NTRS)

    Sarver-Verhey, Timothy R.

    1994-01-01

    A plasma contacting device using a hollow cathode for plasma production has been baselined for use on the Space Station. This application will require reliable, continuous operation of the cathode at electron emission currents of between 0.75 and 10 A for two years (17,500 hours). In order to validate life-time capability, a hollow cathode, operated in a diode configuration, has been tested for more than 8600 hours of stable discharge operation as of March 30, 1994. This cathode is operated at a steady-state emission current of 12.0 and a fixed xenon flow rate of 4.5 sccm. Discharge voltage and cathode temperature have remained relatively stable at approximately 12.9 V and 1260 C during the test. The test has experienced 7 shutdowns to date. In all instances, the cathode was reignited at about 42 V and resumed stable operation. This test represents the longest demonstration of stable operation of high current (greater than 1A) xenon hollow cathodes reported to date.

  19. High Current Cathode Thermal Behavior, Part II: Theory

    NASA Technical Reports Server (NTRS)

    Goodfellow, K. D.; Polk, J. E.

    1993-01-01

    Cathode erosion is one of the life limiting mechanisms for several classes of electric thrusters. Since cathode erosion is strongly dependent on the cathode temperature, a quantitative understanding of the effects of cathode operation on the cathode temperature is required. The development of a cathode/plasma interaction model for determining the heat loads to the cathode as function of the various free stream plasma parameters is presented. This model is combined with a cathode thermal model in order to provide a complete and integrated picture of high current cathode operation.

  20. Development program on a cold cathode electron gun

    NASA Technical Reports Server (NTRS)

    Spindt, C. A.; Holland, C. E.

    1985-01-01

    During this phase of the cathode development program, SRI improved the multiple electron beam exposure system used to print hole patterns for the cathode arrays, studied anisotropic etch processes, conducted cathode investigations using an emission microscope, reviewed possible alternate materials for cathode fabrication, studied cathode storage techniques, conducted high power operation experiments, and demonstrated high-current-density operation with small arrays of tips.

  1. Hollow cathode, quasi-steady MPD arc

    NASA Technical Reports Server (NTRS)

    Parmentier, N.; Jahn, R. G.

    1971-01-01

    A quasi-steady MPD accelerator has been operated with four different hollow cathodes over a power range from 5 kilowatts to 5 megawatts. The absolute level of the argon mass flow, as well as the fractional division of the flow between the cathode and the six standard chamber injectors, is varied over a range of 1 to 12 grams per second. For a fixed total current, it is observed that the voltage increases monotonically with mass flow rate, compared to the usual experience with solid cathodes where the voltage decreases with mass flow rate. For a fixed percentage of flow through the cathode, each hollow cathode configuration displays a minimum impedance at a particular value of the total mass flow. It is asserted that in order to keep the discharge inside the hollow cathode the magnetic pressure and gasdynamic pressure have to match inside the cavity.

  2. Reflective article having a sacrificial cathodic layer

    DOEpatents

    Kabagambe, Benjamin; Buchanan, Michael J.; Scott, Matthew S.; Rearick, Brian K.; Medwick, Paul A.; McCamy, James W.

    2017-09-12

    The present invention relates to reflective articles, such as solar mirrors, that include a sacrificial cathodic layer. The reflective article, more particularly includes a substrate, such as glass, having a multi-layered coating thereon that includes a lead-free sacrificial cathodic layer. The sacrificial cathodic layer includes at least one transition metal, such as a particulate transition metal, which can be in the form of flakes (e.g., zinc flakes). The sacrificial cathodic layer can include an inorganic matrix formed from one or more organo-titanates. Alternatively, the sacrificial cathodic layer can include an organic polymer matrix (e.g., a crosslinked organic polymer matrix formed from an organic polymer and an aminoplast crosslinking agent). The reflective article also includes an outer organic polymer coating, that can be electrodeposited over the sacrificial cathodic layer.

  3. Discharge with Hollow Cathode (Selected Chapters),

    DTIC Science & Technology

    1983-04-12

    view of its mechanism made Rose in [77]. Let us dismantle/select the fundamental conclusions of this work which are based on the study of the...too little in order to support discharge by means of : 7-processes, and therefore the mechanism of secondary processes in the arc with hollow cathode...which leads to the output of electrons from the cathode, thermoemission, then the temperature of cathode surface T3 must be T.=p33OK. Unfortunately, the

  4. Pyrite cathode material for a thermal battery

    NASA Astrophysics Data System (ADS)

    Pemsler, J. P.; Litchfield, J. K.

    1991-02-01

    The present invention relates in general to a synthetic cathode material for a molten salt battery and, more particularly, to a process of providing and using synthetic pyrite for use as a cathode in a thermal battery. These batteries, which have been successfully used in a number of military applications, include iron disulfide cathode material obtained as benefacted or from natural occurring pyrite deposits, or as a byproduct of flotation concentrate from the processing of base or noble metal ores.

  5. HOLLOW CATHODES IN NEGATIVE-GRID TUBES,

    DTIC Science & Technology

    This study involved factors important to the successful operation of hollow cathodes in negative-grid tubes: (1) activation rate; (2) mechanism of...operation; and (3) grid action with truncated pyramidal hollow cathodes. A method of reducing the activation rate by ten-fold was investigated and...et als. Unusual grid-control characteristics associated with hollow cathodes were experimentally derived and indicated the basis for the observed transconductance limitation. (Author)

  6. Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode Operation in Gas Mixtures

    DTIC Science & Technology

    2006-12-15

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6750--06-8992 Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode...Operation in Gas Mixtures Scott Walton Darrin leonharDt richarD FernSler Charged Particle Physics Branch Plasma Physics Division December 15, 2006 Approved...17. LIMITATION OF ABSTRACT Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode Operation in Gas Mixtures Scott Walton, Darrin

  7. Arc initiation in cathodic arc plasma sources

    SciTech Connect

    Anders, Andre

    2002-01-01

    A "triggerless" arc initiation method and apparatus is based on simply switching the arc supply voltage to the electrodes (anode and cathode). Neither a mechanical trigger electrode nor a high voltage flashover from a trigger electrode is required. A conducting path between the anode and cathode is provided, which allows a hot spot to form at a location where the path connects to the cathode. While the conductive path is eroded by the cathode spot action, plasma deposition ensures the ongoing repair of the conducting path. Arc initiation is achieved by simply applying the relatively low voltage of the arc power supply, e.g. 500 V-1 kV, with the insulator between the anode and cathode coated with a conducting layer and the current at the layer-cathode interface concentrated at one or a few contact points. The local power density at these contact points is sufficient for plasma production and thus arc initiation. A conductive surface layer, such as graphite or the material being deposited, is formed on the surface of the insulator which separates the cathode from the anode. The mechanism of plasma production (and arc initiation) is based on explosive destruction of the layer-cathode interface caused by joule heating. The current flow between the thin insulator coating and cathode occurs at only a few contact points so the current density is high.

  8. CO2 laser cold cathode study

    NASA Technical Reports Server (NTRS)

    Hochuli, U.

    1972-01-01

    The procedure for evaluating reliable sputter-free cold cathodes for carbon dioxide lasers is discussed. The purpose of the development is to obtain cold cathodes with service life in excess of 10,000 hours. Discharge tubes are used to eliminate the materials which would be unsatisfactory for use as a cold cathode. A description of the facility for producing the discharge tubes is described. The gas monitoring technique for determining discharge tube performance is examined. Discharge characteristics of tubes with various metals for cathode material are presented in chart form.

  9. Emission properties of explosive field emission cathodes

    SciTech Connect

    Roy, Amitava; Patel, Ankur; Menon, Rakhee; Sharma, Archana; Chakravarthy, D. P.; Patil, D. S.

    2011-10-15

    The research results of the explosive field emission cathode plasma expansion velocity and the initial emission area in the planar diode configuration with cathodes made of graphite, stainless steel, polymer velvet, carbon coated, and carbon fiber (needle type) cathodes are presented. The experiments have been performed at the electron accelerator LIA-200 (200 kV, 100 ns, and 4 kA). The diode voltage has been varied from 28-225 kV, whereas the current density has been varied from 86-928 A/cm{sup 2} with 100 ns pulse duration. The experimentally obtained electron beam diode perveance has been compared with the 1 dimensional Child-Langmuir- law. It was found that initially only a part of the cathode take part in the emission process. The plasma expands at 1.7-5.2 cm/{mu}s for 4 mm anode-cathode gap for various cathode materials. It was found that the plasma expansion velocity increases with the decrease in the cathode diameter. At the beginning of the accelerating pulse, the entire cathode area participates in the electron emission process only for the multiple needle type carbon fiber cathode.

  10. Combined Light Source with Cold and Hot Hollow Cathodes,

    DTIC Science & Technology

    The spectroanalytic characteristics of a double hollow cathode with separated vaporization and excitation zones are given, when employing a cooled hollow cathode as a cathode-exciter. The design of the discharge tube is shown.

  11. Processes For Cleaning a Cathode Tube and Assemblies In A Hollow Cathode Assembly

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J. (Inventor); Verhey, Timothy R. R. (Inventor); Soulas, George C. (Inventor)

    2001-01-01

    The present invention is a process for cleaning a cathode tube and other subassemblies in a hollow cathode assembly. In the disclosed process, hand covering elastomer gloves are used for handling all cathode assembly parts. The cathode tube and other subassemblies are cleaned with a lint-free cloth damped with acetone, then wiped with alcohol, immersed in ethyl alcohol or acetone, and ultrasonic agitation is applied, heating to 60 C. for ethyl alcohol or 56 C. for acetone. The cathode tube and other subassemblies are dried by blowing with nitrogen gas.

  12. Sulfonate-immobilized artificial cathode electrolyte interphases layer on Ni-rich cathode

    NASA Astrophysics Data System (ADS)

    Chae, Bum-Jin; Yim, Taeeun

    2017-08-01

    Although lithium nickel cobalt manganese layered oxides with a high nickel composition have gained great attention due to increased overall energy density for energy conversion/storage systems, poor interfacial stability is considered a critical bottleneck impeding its widespread adoption. We propose a new approach based on immobilizing the artificial cathode-electrolyte interphase layer, which effectively reduces undesired surface reactions, leading to high interfacial stability of cathode material. For installation of artificial cathode-electrolyte interphases, a sulfonate-based amphiphilic organic precursor, which effectively suppresses electrolyte decomposition, is synthesized and subjected to immobilization on cathode material via simple wet-coating, followed by heat treatment at low temperature. The sulfonate-based artificial cathode-electrolyte interphase layer is well-developed on the cathode surface, and the cell controlled by the sulfonate-immobilized cathode exhibits remarkable electrochemical performance, including a high average Coulombic efficiency (99.8%) and cycling retention (97.4%) compared with pristine cathode material. The spectroscopic analyses of the cycled cathode show that the sulfonate-based artificial cathode-electrolyte interphase layer effectively mitigates electrolyte decomposition on the cathode surface, resulting in decreased interfacial resistance between electrode and electrolyte.

  13. Multi-cathode unbalanced magnetron sputtering systems

    NASA Technical Reports Server (NTRS)

    Sproul, William D.

    1991-01-01

    Ion bombardment of a growing film during deposition is necessary in many instances to ensure a fully dense coating, particularly for hard coatings. Until the recent advent of unbalanced magnetron (UBM) cathodes, reactive sputtering had not been able to achieve the same degree of ion bombardment as other physical vapor deposition processes. The amount of ion bombardment of the substrate depends on the plasma density at the substrate, and in a UBM system the amount of bombardment will depend on the degree of unbalance of the cathode. In multi-cathode systems, the magnetic fields between the cathodes must be linked to confine the fast electrons that collide with the gas atoms. Any break in this linkage results in electrons being lost and a low plasma density. Modeling of the magnetic fields in a UBM cathode using a finite element analysis program has provided great insight into the interaction between the magnetic fields in multi-cathode systems. Large multi-cathode systems will require very strong magnets or many cathodes in order to maintain the magnetic field strength needed to achieve a high plasma density. Electromagnets offer the possibility of independent control of the plasma density. Such a system would be a large-scale version of an ion beam enhanced deposition (IBED) system, but, for the UBM system where the plasma would completely surround the substrate, the acronym IBED might now stand for Ion Blanket Enhanced Deposition.

  14. Preliminary Results of Field Emission Cathode Tests

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Kovaleski, Scott D.

    2001-01-01

    Preliminary screening tests of field emission cathodes such as chemical vapor deposited (CVD) diamond, textured pyrolytic graphite, and textured copper were conducted at background pressures typical of electric thruster test facilities to assess cathode performance and stability. Very low power electric thrusters which provide tens to hundreds micronewtons of thrust may need field emission neutralizers that have a capability of tens to hundreds of microamperes. From current voltage characteristics, it was found that the CVD diamond and textured metals cathodes clearly satisfied the Fowler-Nordheim emission relation. The CVD diamond and a textured copper cathode had average current densities of 270 and 380 mA/sq cm, respectively, at the beginning-of-life. After a few hours of operation the cathode emission currents degraded by 40 to 75% at background pressures in the 10(exp -5) Pa to 10(exp -4) Pa range. The textured pyrolytic graphite had a modest current density at beginning-of-life of 84 mA/sq cm, but this cathode was the most stable of all. Extended testing of the most promising cathodes is warranted to determine if current degradation is a burn-in effect or whether it is a long-term degradation process. Preliminary experiments with ferroelectric emission cathodes, which are ceramics with spontaneous electric polarization, were conducted. Peak current densities of 30 to 120 mA/sq cm were obtained for pulse durations of about 500 ns in the 10(exp -4) Pa pressure range.

  15. Cathode Effects in Cylindrical Hall Thrusters

    SciTech Connect

    Granstedt, E.M.; Raitses, Y.; Fisch, N. J.

    2008-09-12

    Stable operation of a cylindrical Hall thruster (CHT) has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode-neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.

  16. Dual cathode system for electron beam instruments

    NASA Technical Reports Server (NTRS)

    Bradley, James G. (Inventor); Conley, Joseph M. (Inventor); Wittry, David B. (Inventor)

    1989-01-01

    An electron beam source having a single electron optical axis is provided with two coplanar cathodes equally spaced on opposite sides from the electron optical axis. A switch permits selecting either cathode, and a deflection system comprised of electromagnets, each with separate pole pieces equally spaced from the plane of the cathodes and electron optical axis, first deflects the electron beam from a selected cathode toward the electron optical axis, and then in an opposite direction into convergence with the electron optical axis. The result is that the electron beam from one selected cathode undergoes a sigmoid deflection in two opposite directions, like the letter S, with the sigmoid deflection of each being a mirror image of the other.

  17. Performance analysis of new cathode materials for molten carbonate fuel cells

    NASA Astrophysics Data System (ADS)

    Paoletti, C.; Carewska, M.; Presti, R. Lo; Phail, S. Mc; Simonetti, E.; Zaza, F.

    The slow dissolution of the lithiated nickel oxide cathode represents one of the main causes of performance degradation in molten carbonate fuel cells (MCFC). Two main approaches were studied in ENEA laboratories to overcome this problem: protecting the nickel cathode covering it by a thin layer of a material with a low solubility in molten carbonate and stabilizing the nickel cathode doping it with iron and magnesium. Among several materials, due to its low solubility and good conductivity, lithium cobaltite was chosen to cover the nickel cathode and slow down its dissolution. A nickel electrode covered with a thin layer of lithium cobaltite doped with magnesium, was fabricated by complex sol-gel process. To simplify electrode preparation, no thermal treatments were made after covering to produce lithium cobaltite, and during the cell start-up LiMg 0.05Co 0.95O 2 was obtained in situ. To stabilize the nickel cathode, metal oxides Fe 2O 3 and MgO were chosen as dopant additives to be mixed with NiO powder in a tape-casting process (Mg 0.05Fe 0.01Ni 0.94O). On the prepared materials TGA analysis, morphological analysis by scanning electron microscopy (SEM-EDS) and electrical conductivity measurements were carried out. A conventional nickel cathode, the nickel cathode covered by lithium cobaltite precursors and the nickel cathode stabilized by iron and magnesium oxides were each tested in a 100 cm 2 fuel cell. Polarization curves and internal resistance (iR) measurements were acquired during the cell lifetime (1000 h) and the effect of gas composition variation on the cell performance was studied. From a comparison with the conventional nickel cathode it can be observed that the new materials have similar performance and show a good potential stability during the cell operating time. From the post-test analysis both the nickel cathode covered by lithium cobaltite and the nickel cathode doped with iron and magnesium seem to succeed in reducing nickel dissolution.

  18. Thermal and electrochemical properties of PEO-LiTFSI-Pyr14TFSI-based composite cathodes, incorporating 4 V-class cathode active materials

    NASA Astrophysics Data System (ADS)

    Wetjen, Morten; Kim, Guk-Tae; Joost, Mario; Appetecchi, Giovanni B.; Winter, Martin; Passerini, Stefano

    2014-01-01

    Poly(ethylene oxide)-lithium bis(trifluoromethanesulfonyl)imide N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PEO-LiTFSI-Pyr14TFSI)-based 4 V-class composite cathodes, incorporating either Li(Ni1/3Co1/3Mn1/3)O2 or Li(Ni0.8Co0.15Al0.05)O2 were prepared by a hot-pressing process and successively investigated in terms of their morphological, thermal, and electrochemical properties. Thereby, excellent mechanical and thermal properties could be demonstrated for all composite cathodes. The electrochemical performance of truly dry all-solid-state Li/P(EO)10LiTFSI-(Pyr14TFSI)2/composite cathode batteries at temperatures as low as 40 °C revealed high delivered capacities. However, in comparison with LiFePO4, the 4 V-class composite cathodes also indicated much lower capacity retention. In-depth investigations on the interfacial properties of Li(Ni0.8Co0.15Al0.05)O2 composite cathodes revealed a strong dependence on the anodic cut-off potential and the presence of current flow through the cell, whereby different degradation mechanisms could be characterized upon cycling, according to which the finite growth of a surface films at both electrode/polymer electrolyte interfaces inhibited continuous decomposition of the polymer electrolyte even at potentials as high as 4.3 V. Moreover, the presence of Pyr14TFSI in the 4 V-class composite cathodes sustainably reduced the cathode interfacial resistance and presumably diminished the corrosion of the aluminum current collector.

  19. Emission, plasma formation, and brightness of a PZT ferroelectric cathode

    SciTech Connect

    Sampayan, S.; Caporaso, G.; Trimble, D.; Westenskow, G.

    1995-04-27

    We have measured an 36-A-cm{sup {minus}2} current emission density over the surface area of an 11.4-cm{sup 2}-area Lead-Titanate- Zirconate (PZT) ferroelectric cathode with a pulsed anode-cathode (A-K) potential of 50 kV. We have also observed currents above those predicted by classical Child-Langmuir formula for a wide variety of cases. Since a plasma within the A-K gap could also lead to increase current emission we are attempting to measure the properties of the plasma near the cathode surface at emission time. In other measurements, we have observed strong gap currents in the absence of an A-K potential. Further, we continue to make brightness measurements of the emitted beam and observe spatially non-uniform emission and large shot-to-shot variation. Measurements show individual beamlets with a brightness as high 10{sup 11} Am{sup {minus}2} rad{sup {minus}2}.

  20. Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

    SciTech Connect

    Causa, Federica; Ghezzi, Francesco; Caniello, Roberto; Grosso, Giovanni; Dellasega, David

    2012-12-15

    Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

  1. Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

    NASA Astrophysics Data System (ADS)

    Causa, Federica; Ghezzi, Francesco; Dellasega, David; Caniello, Roberto; Grosso, Giovanni

    2012-12-01

    Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

  2. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a...

  3. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a...

  4. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a...

  5. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet the...

  6. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet the...

  7. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet the...

  8. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet the...

  9. Polarization switching in ferroelectric cathodes

    SciTech Connect

    Rosenman, G.; Shur, D.; Garb, K.; Cohen, R.; Krasik, Y.E.

    1997-07-01

    A new mechanism of polarization switching and electron emission in ferroelectric cathodes is proposed. Surface flashover plasma of a ferroelectric origin was observed on a polar ferroelectric surface [D. Shur, G. Rosenman, and Ya. E. Krasik, Appl. Phys. Lett. {bold 70}, 574 (1997)]. Simultaneous measurements of switched charge and plasma density show that expanding surface plasma represents a dynamic switching electrode. Direct measurements of ion/electron emission currents and surface analysis implemented by different analytic tools indicate that electrons and ions from the surface plasma contribute to spontaneous polarization screening. The high energy of charged particles emitted from the surface plasma is ascribed to a high surface potential during polarization switching. {copyright} {ital 1997 American Institute of Physics.}

  10. Cathode for an electrochemical cell

    DOEpatents

    Bates, John B.; Dudney, Nancy J.; Gruzalski, Greg R.; Luck, Christopher F.

    2001-01-01

    Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode. Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

  11. Operational Status of the International Space Station Plasma Contactor Hollow Cathode Assemblies July 2001 to May 2013

    NASA Technical Reports Server (NTRS)

    Kamhawi, Hani; Yim, John T.; Patterson, Michael J.; Dalton, Penni J.

    2013-01-01

    The International Space Station has onboard two Aerojet Rocketdyne developed plasma contactor units that perform the function of charge control. The plasma contactor units contain NASA Glenn Research Center developed hollow cathode assemblies. NASA Glenn Research Center monitors the on-orbit operation of the flight hollow cathode assemblies. As of May 31, 2013, HCA.001-F has been ignited and operated 123 times and has accumulated 8072 hours of operation, whereas, HCA.003-F has been ignited and operated 112 times and has accumulated 9664 hours of operation. Monitored hollow cathode ignition times and anode voltage magnitudes indicate that they continue to operate nominally.

  12. Operational Status of the International Space Station Plasma Contactor Hollow Cathode Assemblies from July 2011 to May 2013

    NASA Technical Reports Server (NTRS)

    Kamhawi, Hani; Yim, John T.; Patterson, Michael J.; Dalton, Penni J.

    2014-01-01

    The International Space Station has onboard two Aerojet Rocketdyne developed plasma contactor units that perform the function of charge control. The plasma contactor units contain NASA Glenn Research Center developed hollow cathode assemblies. NASA Glenn Research Center monitors the onorbit operation of the flight hollow cathode assemblies. As of May 31, 2013, HCA.001-F has been ignited and operated 123 times and has accumulated 8072 hours of operation, whereas, HCA.003-F has been ignited and operated 112 times and has accumulated 9664 hours of operation. Monitored hollow cathode ignition times and anode voltage magnitudes indicate that they continue to operate nominally.

  13. Advances in primary lithium liquid cathode batteries

    NASA Astrophysics Data System (ADS)

    Blomgren, George E.

    1989-05-01

    Recent work on cell development and various aspects of cell chemistry and cell development of lithium/thionyl chloride liquid cathode batteries is reviewed. As a result of safety studies, a number of cell sizes can now be considered satisfactory for many applications and the energy densities of these cells is higher than any other developed battery system. Primary batteries operate with low to moderate currents and the anode delay effect appears to be under reasonable control. Reserve cells are in the design stage and operate at high to very high power densities as well as very high energy densities. The nature of the anode film and the operation of the lithium anode has been studied with substantial success and understanding has grown accordingly. Also, studies of the structure of the electrolyte and the effects on the electrolyte of impurities and additives have led to improved understanding in this area as well. Work in progress on new electrolytes is reviewed. The state of the art of mathematical modeling is also discussed and it is expected that this work will continue to develop.

  14. Batteries: Overview of Battery Cathodes

    SciTech Connect

    Doeff, Marca M

    2010-07-12

    The very high theoretical capacity of lithium (3829 mAh/g) provided a compelling rationale from the 1970's onward for development of rechargeable batteries employing the elemental metal as an anode. The realization that some transition metal compounds undergo reductive lithium intercalation reactions reversibly allowed use of these materials as cathodes in these devices, most notably, TiS{sub 2}. Another intercalation compound, LiCoO{sub 2}, was described shortly thereafter but, because it was produced in the discharged state, was not considered to be of interest by battery companies at the time. Due to difficulties with the rechargeability of lithium and related safety concerns, however, alternative anodes were sought. The graphite intercalation compound (GIC) LiC{sub 6} was considered an attractive candidate but the high reactivity with commonly used electrolytic solutions containing organic solvents was recognized as a significant impediment to its use. The development of electrolytes that allowed the formation of a solid electrolyte interface (SEI) on surfaces of the carbon particles was a breakthrough that enabled commercialization of Li-ion batteries. In 1990, Sony announced the first commercial batteries based on a dual Li ion intercalation system. These devices are assembled in the discharged state, so that it is convenient to employ a prelithiated cathode such as LiCoO{sub 2} with the commonly used graphite anode. After charging, the batteries are ready to power devices. The practical realization of high energy density Li-ion batteries revolutionized the portable electronics industry, as evidenced by the widespread market penetration of mobile phones, laptop computers, digital music players, and other lightweight devices since the early 1990s. In 2009, worldwide sales of Li-ion batteries for these applications alone were US$ 7 billion. Furthermore, their performance characteristics (Figure 1) make them attractive for traction applications such as hybrid

  15. Cathode for molten carbonate fuel cell

    DOEpatents

    Kaun, Thomas D.; Mrazek, Franklin C.

    1990-01-01

    A porous sintered cathode for a molten carbonate fuel cell and method of making same, the cathode including a skeletal structure of a first electronically conductive material slightly soluble in the electrolyte present in the molten carbonate fuel cell covered by fine particles of a second material of possibly lesser electronic conductivity insoluble in the electrolyte present in the molten carbonate fuel cell, the cathode having a porosity in the range of from about 60% to about 70% at steady-state cell operating conditions consisting of both macro-pores and micro-pores.

  16. Numerical study on rectangular microhollow cathode discharge

    SciTech Connect

    He Shoujie; Ouyang Jiting; He Feng; Li Shang

    2011-03-15

    Rectangular microhollow cathode discharge in argon is investigated by using two-dimensional time-dependent self-consistent fluid model. The electric potential, electric field, particle density, and mean electron energy are calculated. The results show that hollow cathode effect can be onset in the present configuration, with strong electric field and high mean electron energy in the cathode fall while high density and quasineutral plasma in the negative glow. The potential well and electric filed reversal are formed in the negative glow region. It is suggested that the presence of large electron diffusion flux necessitates the field reversal and potential well.

  17. Note: Coaxial-heater hollow cathode

    NASA Astrophysics Data System (ADS)

    Kurt, Huseyin; Kokal, Ugur; Turan, Nazli; Celik, Murat

    2017-06-01

    The design and tests of a LaB6 hollow cathode with a novel heater are presented. In the new design, the heater wire is completely encapsulated around the cathode tube and a coaxial return electrode, thereby eliminating hot spots on the heater wire due to the free hanging regions. Since the new heater confines the Joule heating to the region of interest, where the LaB6 emitter is placed, the heater terminals are further secured from overheating. The cathode with the presented heater design has been successfully tested and is able to deliver currents in the 0.5-15 A range.

  18. Cells having cathodes containing polycarbon disulfide materials

    DOEpatents

    Okamoto, Yoshi; Skotheim, Terje A.; Lee, Hung S.

    1995-08-15

    The present invention relates to an electric current producing cell which contains an anode, a cathode having as a cathode-active material one or more carbon-sulfur compounds of the formula (CS.sub.x).sub.n, in which x takes values from 1.2 to 2.3 and n is greater or equal to 2, and where the redox process does not involve polymerization and de-polymerization by forming and breaking S--S bonds in the polymer backbone. The cell also contains an electrolyte which is chemically inert with respect to the anode and the cathode.

  19. Cells having cathodes containing polycarbon disulfide materials

    DOEpatents

    Okamoto, Y.; Skotheim, T.A.; Lee, H.S.

    1995-08-15

    The present invention relates to an electric current producing cell which contains an anode, a cathode having as a cathode-active material one or more carbon-sulfur compounds of the formula (CS{sub x}){sub n}, in which x takes values from 1.2 to 2.3 and n is greater or equal to 2, and where the redox process does not involve polymerization and de-polymerization by forming and breaking S--S bonds in the polymer backbone. The cell also contains an electrolyte which is chemically inert with respect to the anode and the cathode. 5 figs.

  20. A Poisoning Study of Nickel Matrix Cathodes.

    DTIC Science & Technology

    1980-07-24

    processing. CO2 tends to poison these cathodes so it will be important to determine the origin of CO, and eliminate it. .L Another activation of a 558 cathode...that the cathode did not comoletelv recover from the fourth poisoning . It took some 1700 minutes to recover to 63Y of its original emission current...fall to 37. of the original current upon poisoning and the time to recover to 63*, of the original current after the gas leak had been shut off. The

  1. K2CsSb Cathode Development

    SciTech Connect

    Smedley,J.; Rao, T.; Wang, E.

    2008-10-01

    K{sub 2}CsSb is an attractive photocathode for high current applications. With a quantum efficiency of >4% at 532nm and >10% at 355nm, it is the only cathode to have demonstrated an average current of 35mA in an accelerator environment We describe ongoing cathode development work. for the energy recovery linac being constructed at BNL Several cathodes have been created on both copper and stainless steel substrates, and their spatial uniformity and spectral response have been characterized. Preliminary lifetime measurements have been performed at high average current densities (>1 mA/mm{sup 2}).

  2. Cathode for molten carbonate fuel cell

    DOEpatents

    Kaun, Thomas D.; Mrazek, Franklin C.

    1990-01-01

    A porous sintered cathode for a molten carbonate fuel cell and method of making same, the cathode including a skeletal structure of a first electronically conductive material slightly soluble in the electrolyte present in the molten carbonate fuel cell covered by fine particles of a second material of possibly lesser electronic conductivity insoluble in the electrolyte present in the molten carbonate fuel cell, the cathode having a porosity in the range of from about 60% to about 70% at steady-state cell operating conditions consisting of both macro-pores and micro-pores.

  3. Plasma distribution of cathodic ARC deposition system

    SciTech Connect

    Anders, S.; Raoux, S.; Krishnan, K.; MacGill, R.A.; Brown, I.G.

    1996-08-01

    The plasma distribution using a cathodic arc plasma source with and without magnetic macroparticle filter has been determined by depositing on a transparent plastic substrate and measuring the film absorption. It was found that the width of the distribution depends on the arc current, and it also depends on the cathode material which leads to a spatial separation of the elements when an alloy cathode is used. By applying a magnetic multicusp field near the exit of the magnetic filter, it was possible to modify the plasma distribution and obtain a flat plasma profile with a constant and homogeneous elemental distribution.

  4. High power microwave generation from coaxial virtual cathode oscillator using graphite and velvet cathodes

    NASA Astrophysics Data System (ADS)

    Menon, Rakhee; Roy, Amitava; Singh, S. K.; Mitra, S.; Sharma, Vishnu; Kumar, Senthil; Sharma, Archana; Nagesh, K. V.; Mittal, K. C.; Chakravarthy, D. P.

    2010-05-01

    High power microwave (HPM) generation studies were carried out in KALI-5000 pulse power system. The intense relativistic electron beam was utilized to generate HPMs using a coaxial virtual cathode oscillator. The typical electron beam parameters were 350 kV, 25 kA, and 100 ns, with a few hundreds of ampere per centimeter square current density. Microwaves were generated with graphite and polymer velvet cathode at various diode voltage, current, and accelerating gaps. A horn antenna setup with diode detector and attenuators was used to measure the microwave power. It was observed that the microwave power increases with the diode voltage and current and reduces with the accelerating gap. It was found that both the peak power and width of the microwave pulse is larger for the velvet cathode compared to the graphite cathode. In a coaxial vircator, velvet cathode is superior to the graphite cathode due to its shorter turn on time and better electron beam uniformity.

  5. Nanoporous silver cathode surface treated by atomic layer deposition of CeO(x) for low-temperature solid oxide fuel cells.

    PubMed

    Neoh, Ke Chean; Han, Gwon Deok; Kim, Manjin; Kim, Jun Woo; Choi, Hyung Jong; Park, Suk Won; Shim, Joon Hyung

    2016-05-06

    We evaluated the performance of solid oxide fuel cells (SOFCs) with a 50 nm thin silver (Ag) cathode surface treated with cerium oxide (CeO(x)) by atomic layer deposition (ALD). The performances of bare and ALD-treated Ag cathodes were evaluated on gadolinia-doped ceria (GDC) electrolyte supporting cells with a platinum (Pt) anode over 300 °C-450 °C. Our work confirms that ALD CeO(x) treatment enhances cathodic performance and thermal stability of the Ag cathode. The performance difference between cells using a Ag cathode optimally treated with an ALD CeO(x) surface and a reference Pt cathode is about 50% at 450 °C in terms of fuel cell power output in our experiment. The bare Ag cathode completely agglomerated into islands during fuel cell operation at 450 °C, while the ALD CeO(x) treatment effectively protects the porosity of the cathode. We also discuss the long-term stability of ALD CeO(x)-treated Ag cathodes related to the microstructure of the layers.

  6. Nanoporous silver cathode surface treated by atomic layer deposition of CeO x for low-temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Chean Neoh, Ke; Han, Gwon Deok; Kim, Manjin; Kim, Jun Woo; Jong Choi, Hyung; Park, Suk Won; Shim, Joon Hyung

    2016-05-01

    We evaluated the performance of solid oxide fuel cells (SOFCs) with a 50 nm thin silver (Ag) cathode surface treated with cerium oxide (CeO x ) by atomic layer deposition (ALD). The performances of bare and ALD-treated Ag cathodes were evaluated on gadolinia-doped ceria (GDC) electrolyte supporting cells with a platinum (Pt) anode over 300 °C-450 °C. Our work confirms that ALD CeO x treatment enhances cathodic performance and thermal stability of the Ag cathode. The performance difference between cells using a Ag cathode optimally treated with an ALD CeO x surface and a reference Pt cathode is about 50% at 450 °C in terms of fuel cell power output in our experiment. The bare Ag cathode completely agglomerated into islands during fuel cell operation at 450 °C, while the ALD CeO x treatment effectively protects the porosity of the cathode. We also discuss the long-term stability of ALD CeO x -treated Ag cathodes related to the microstructure of the layers.

  7. Low temperature aluminum reduction cell using hollow cathode

    DOEpatents

    Brown, Craig W.; Frizzle, Patrick B.

    2002-08-20

    A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte. A plurality of non-consumable anodes are disposed substantially vertically in the electrolyte along with a plurality of monolithic hollow cathodes. Each cathode has a top and bottom and the cathodes are disposed vertically in the electrolyte and the anodes and the cathodes are arranged in alternating relationship. Each of the cathodes is comprised of a first side facing a first opposing anode and a second side facing a second opposing anode. The first and second sides are joined by ends to form a reservoir in the hollow cathode for collecting aluminum therein deposited at the cathode.

  8. 49 CFR 192.613 - Continuing surveillance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... appropriate action concerning changes in class location, failures, leakage history, corrosion, substantial changes in cathodic protection requirements, and other unusual operating and maintenance conditions. (b... exists, the operator shall initiate a program to recondition or phase out the segment involved, or, if...

  9. Electrolyte and Cathode Degradation Mechanisms in Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Tebbe, Jonathon

    Lithium ion battery technologies suffer from limitations in performance, such as capacity fading, due in part to degradation of the cathode and electrolyte materials. Quantum chemical simulations were employed to investigate the reactions leading to degradation of LiCoO2 cathodes and the electrolyte molecules. Formation of HF in the electrolyte resulting from reaction between PF5 and H2O impurities was first investigated. This research predicts HF is produced as a result of PF5 complexing with H2O, then reacting through ligand exchange to form HF and PF4OH with an activation barrier of 1.18 eV and reaction enthalpy of 0.15 eV. HF undergoes dissociative adsorption at that the (101¯4) surface of LiCoO2 without a barrier, leading to formation of LiF-Li+ precipitates and H 2O on the surface with a reaction energy of -2.41 eV. The formation of H2O is of particular concern because H2O drives further formation of HF in the electrolyte, resulting in an autocatalytic cycle of degradation. These findings indicate that HF initially occurs in low concentrations rapidly increases due to H2O generation upon HF attack. Reduction in capacity fading is observed in alumina ALD coated LiCoO2 cathodes and we have investigated a monolayer alumina coating on the LiCoO2 (101¯4) surface to identify the mechanism by which the alumina coating protects the cathode surface. We have found that HF will preferentially dissociate at the alumina coating with a reaction energy of -2.84 eV and without any resolvable barrier to dissociation. Additionally, our calculations predict that H2O does not form as a result of HF dissociation at the alumina monolayer; instead HF dissociation produces neighboring hydroxyl sites on the alumina surface. Consequently, the alumina coating prevents the autocatalytic degradation of the cathode by sequestering HF impurities in the alumina film. Finally, we found that Lewis acid-base complexation between ethylene carbonate (EC) electrolyte molecules and PF5 or the Li

  10. Mechanical properties and fracture strength of cathodically polarized prestressing wire

    SciTech Connect

    Kiszowski, S.; Hartt, W.H.

    1996-11-01

    Constant extension rate testing experiments were performed upon prestressing steel wire specimens prepared from three lots of Grade 270 and one lot of Grade 250 material for the purpose of characterizing susceptibility to environmental cracking under conditions associated with cathodic protection of prestressed concrete components and structures. Smooth, notched (six different geometries) and pitted (four different geometries) specimens were tested in air and deaerated saturated Ca(OH){sub 2}-distilled water at potentials of {minus}0.90 and {minus}1.30 v (SCE) and strength and ductility properties characterized. Relatively low strength was recorded for steel specimens at {minus}09.90 v from material for which the weight percent chromium was relatively high (0.24 w/o compared to 0.02 w/o). Under conditions that are likely to be most relevant to service, fracture load correlated with the amount by which the local wire cross section area was reduced, either from a notch or pit, and was independent of depth of the irregularity and of root radius to the extent to which these were addressed. It was concluded that it may be unsafe to apply cathodically protection to prestressing wire, even in situations where potential is maintained in the regime where hydrogen embrittlement should not occur.

  11. Distribution of the current on metallic structures with corrosion damage under nonlinear cathodic polarization

    SciTech Connect

    Galimov, A.A.; Glazov, N.P.; Ivanov, V.T.

    1985-08-01

    The protection of metallic structures from corrosion is effected by cathodic polarization and protective coatings. At sites of damage extending through the insulation an intense corrosion process, which causes the formation of corrosion pits, in which signifiant redistribution of the protective current occurs, takes place. Considered in this paper is the distribution of the current on an electrode with a corrosion pit of arbitrary shape in the example of an electrochemical system consisting of disk electrodes located in a cylindrical bath with a lateral insulator surface. The overall analysis of the numerical results points out the significant redistribution of the current on a protected metallic surface when corrosion pits appear.

  12. Plasma-cathode-initiated vacuum gap closure

    SciTech Connect

    Sampayan, S.E.; Gurbaxani, S.H. ); Buttram, M.T. )

    1990-09-01

    The properties of vacuum gap closure initiated by a plasma cathode are presented. The plasma cathode consisted of approximately 60 surface flashover sites distributed over a 10-cm{sup 2} area. Vacuum gap dimensions were 1{times}7.5 cm in diameter. Faraday cup measurements indicated an ion density greater than 10{sup 12} cm{sup {minus}3}, which was controllable by the amplitude of the initiating high-voltage pulse. Although the field-free expansion velocity of the plasma was measured to be 7 cm/{mu}s, plasma-cathode-initiated closure of the vacuum gap indicated closure speeds on the order of 0.5 cm/{mu}s. Also, increased injected ion density and increased anode-cathode potential resulted in increased closure velocity.

  13. Companies Exporting Cathode Ray Tubes for Reuse

    EPA Pesticide Factsheets

    Companies listed in the table below have submitted written notifications to EPA Headquarters to inform EPA of their intention to export used, intact cathode ray tubes (CRTs) for reuse as required under the CRT rule.

  14. Corrosion/Fragmentation of Layered Composite Cathode and Related Capacity/Voltage Fading during Cycling Process

    SciTech Connect

    Zheng, Jianming; Gu, Meng; Xiao, Jie; Zuo, Pengjian; Wang, Chong M.; Zhang, Jiguang

    2013-06-26

    Pristine and cycled layered structure cathode of Li[Li0.2Ni0.2M0.6]O2 samples are characterized by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. These analyses provide new insights on capacity/voltage fading mechanism of Li[Li0.2Ni0.2M0.6]O2. Sponge-like structure and fragment pieces were found on the surface of cathode after cycling. Mn2+ species and reduced Li content in the fragments caused significant capacity loss. These results also reveal the functional mechanism of surface coatings, e.g. AlF3, which can protect the electrode from etching by acidic species in the electrolyte, suppress cathode degradation and improve long-term cycling stability.

  15. Galvanic Liquid Applied Coating System for Protection of Embedded Steel Surfaces from Corrosion

    NASA Technical Reports Server (NTRS)

    Curran, Joseph; MacDowell, Louis; Voska, N. (Technical Monitor)

    2002-01-01

    The corrosion of reinforcing steel in concrete is an insidious problem for the Kennedy Space Center, government agencies, and the general public. Existing corrosion protection systems on the market are costly, complex, and time-consuming to install, require continuous maintenance and monitoring, and require specialized skills for installation. NASA's galvanic liquid-applied coating offers companies the ability to conveniently protect embedded steel rebar surfaces from corrosion. Liquid-applied inorganic galvanic coating contains one ore more of the following metallic particles: magnesium, zinc, or indium and may contain moisture attracting compounds that facilitate the protection process. The coating is applied to the outer surface of reinforced concrete so that electrical current is established between metallic particles and surfaces of embedded steel rebar; and electric (ionic) current is responsible for providing the necessary cathodic protection for embedded rebar surfaces.

  16. Co-Flow Hollow Cathode Technology

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

    Hall thrusters utilize identical hollow cathode technology as ion thrusters, yet must operate at much higher mass flow rates in order to efficiently couple to the bulk plasma discharge. Higher flow rates are necessary in order to provide enough neutral collisions to transport electrons across magnetic fields so that they can reach the discharge. This higher flow rate, however, has potential life-limiting implications for the operation of the cathode. A solution to the problem involves splitting the mass flow into the hollow cathode into two streams, the internal and external flows. The internal flow is fixed and set such that the neutral pressure in the cathode allows for a high utilization of the emitter surface area. The external flow is variable depending on the flow rate through the anode of the Hall thruster, but also has a minimum in order to suppress high-energy ion generation. In the co-flow hollow cathode, the cathode assembly is mounted on thruster centerline, inside the inner magnetic core of the thruster. An annular gas plenum is placed at the base of the cathode and propellant is fed throughout to produce an azimuthally symmetric flow of gas that evenly expands around the cathode keeper. This configuration maximizes propellant utilization and is not subject to erosion processes. External gas feeds have been considered in the past for ion thruster applications, but usually in the context of eliminating high energy ion production. This approach is adapted specifically for the Hall thruster and exploits the geometry of a Hall thruster to feed and focus the external flow without introducing significant new complexity to the thruster design.

  17. Interfacial phenomena on selected cathode materials

    SciTech Connect

    Kostecki, Robert; Matsuo, Yoshiaki; McLarnon, Frank

    2001-06-22

    We have carried out a series of surface studies of selected cathode materials. Instrumental techniques such as Raman microscopy, surface enhanced Raman spectroscopy (SERS), and atomic force microscopy were used to investigate the cathode surfaces. The goal of this study was to identify detrimental processes which occur at the electrode/electrolyte interface and can lead to electrode degradation and failure during cycling and/or storage at elevated temperatures.

  18. Model for designing planar magnetron cathodes

    SciTech Connect

    Garcia, M.

    1997-05-30

    Planar magnetron cathodes have arching magnetic field lines which concentrate plasma density to enhance ion bombardment and sputtering. Typical parameters are: helium at 1 to 300 milli-torr, 200 to 2000 gauss at the cathode, 200 to 800 volts, and plasma density decreasing by up to ten times within 2 to 10 cm from the cathode. A 2D, quasineutral, fluid model yields formulas for the plasma density: n(x,y), current densities: j(x,y), j{sub e}(x,y), j{sub +}(x,y), the electric field: E{sub y}(y), and the voltage between the cathode surface and a distant plasma. An ion sheath develops between the cathode and the quasineutral flow. The thickness of this sheath depends on processes in the quasineutral flow. Experiments shows that T{sub e} (3 {yields} 8 eV) adjusts to ensure that {alpha}{sub 0}{tau} {approx} 2.5 in helium, for ionization rate {alpha}{sub 0} (10{sup 4} {yields} 10{sup 5} s{sup -1}), and electron transit time to the unmagnetized plasma {tau} (10 {yields} 100 {micro}s). Helium glow discharge cathode fall {alpha}{sub 0}{tau} is about 2.5, though this occurs at much higher voltage.

  19. Development of plasma cathode electron guns

    NASA Astrophysics Data System (ADS)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

    The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

  20. Ir-coated dispenser cathode for CRT

    NASA Astrophysics Data System (ADS)

    Kimura, Sakae; Yakabe, Toru; Matsumoto, Sadao; Miyazaki, Daisuke; Yoshii, Tsuyoshi

    1990-12-01

    A compact dispenser cathode has been developed for application to CRTs. A cathode emitter, comprising BaO, CaO, and Al2O3 in a molar ratio of 4:1:1, was impregnated into a porous tungsten pellet. An intermetallic compound of tungsten and iridium was formed on the cathode pellet. Heater ratings were 6.3 V x 0.2 A. Emission characteristics were measured by using color CRTs. As a result, a cathode peak loading of 15 A/sq cm was ensured in the space-charge region. Furthermore, life tests with a peak loading of 7.5 A/sq cm were conducted over 10,000 h. The decrease in emission current after 10 000 h was within only 10 percent of the initial value. Reliability of cathode performance was assured in terms of breakdown potential between the heater and the cathode, emission characteristics, life performance, grid emission, and the drift in cutoff potential. In addition, the effects of the coating thickness on the emission characteristics are discussed.

  1. Uncovering the role of cathode buffer layer in organic solar cells

    NASA Astrophysics Data System (ADS)

    Qi, Boyuan; Zhang, Zhi-Guo; Wang, Jizheng

    2015-01-01

    Organic solar cells (OSCs) as the third generation photovoltaic devices have drawn intense research, for their ability to be easily deposited by low-cost solution coating technologies. However the cathode in conventional OSCs, Ca, can be only deposited by thermal evaporation and is highly unstable in ambient. Therefore various solution processible cathode buffer layers (CBLs) are synthesized as substitute of Ca and show excellent effect in optimizing performance of OSCs. Yet, there is still no universal consensus on the mechanism that how CBL works, which is evidently a critical scientific issue that should be addressed. In this article detailed studies are targeted on the interfacial physics at the interface between active layer and cathode (with and without treatment of a polar CBL) by using ultraviolet photoelectron spectroscopy, capacitance-voltage measurement, and impedance spectroscopy. The experimental data demonstrate that CBL mainly takes effect in three ways: suppressing surface states at the surface of active layer, protecting the active layer from being damaged by thermally evaporated cathode, and changing the energy level alignment by forming dipole moments with active layer and/or cathode. Our findings here provide a comprehensive picture of interfacial physics in devices with and without CBL.

  2. Uncovering the role of cathode buffer layer in organic solar cells

    PubMed Central

    Qi, Boyuan; Zhang, Zhi-Guo; Wang, Jizheng

    2015-01-01

    Organic solar cells (OSCs) as the third generation photovoltaic devices have drawn intense research, for their ability to be easily deposited by low-cost solution coating technologies. However the cathode in conventional OSCs, Ca, can be only deposited by thermal evaporation and is highly unstable in ambient. Therefore various solution processible cathode buffer layers (CBLs) are synthesized as substitute of Ca and show excellent effect in optimizing performance of OSCs. Yet, there is still no universal consensus on the mechanism that how CBL works, which is evidently a critical scientific issue that should be addressed. In this article detailed studies are targeted on the interfacial physics at the interface between active layer and cathode (with and without treatment of a polar CBL) by using ultraviolet photoelectron spectroscopy, capacitance-voltage measurement, and impedance spectroscopy. The experimental data demonstrate that CBL mainly takes effect in three ways: suppressing surface states at the surface of active layer, protecting the active layer from being damaged by thermally evaporated cathode, and changing the energy level alignment by forming dipole moments with active layer and/or cathode. Our findings here provide a comprehensive picture of interfacial physics in devices with and without CBL. PMID:25588623

  3. Electricity generation and bivalent copper reduction as a function of operation time and cathode electrode material in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Wu, Dan; Huang, Liping; Quan, Xie; Li Puma, Gianluca

    2016-03-01

    The performance of carbon rod (CR), titanium sheet (TS), stainless steel woven mesh (SSM) and copper sheet (CS) cathode materials are investigated in microbial fuel cells (MFCs) for simultaneous electricity generation and Cu(II) reduction, in multiple batch cycle operations. After 12 cycles, the MFC with CR exhibits 55% reduction in the maximum power density and 76% increase in Cu(II) removal. In contrast, the TS and SSM cathodes at cycle 12 show maximum power densities of 1.7 (TS) and 3.4 (SSM) times, and Cu(II) removal of 1.2 (TS) and 1.3 (SSM) times higher than those observed during the first cycle. Diffusional resistance in the TS and SSM cathodes is found to appreciably decrease over time due to the copper deposition. In contrast to CR, TS and SSM, the cathode made with CS is heavily corroded in the first cycle, exhibiting significant reduction in both the maximum power density and Cu(II) removal at cycle 2, after which the performance stabilizes. These results demonstrate that the initial deposition of copper on the cathodes of MFCs is crucial for efficient and continuous Cu(II) reduction and electricity generation over prolonged time. This effect is closely associated with the nature of the cathode material. Among the materials examined, the SSM is the most effective and inexpensive cathode for practical use in MFCs.

  4. Enhancements to Boundary Element Cathodic Protection Simulation Software

    DTIC Science & Technology

    2002-02-01

    navire. Nous avons effectue des modifications pour tenir compte de plusieurs courbes de polarisation et de regions ou Ia peinture est endommagee. En...mailles et le contr6le des anodes), ainsi que de nouvelles commandes permettant de decrire les courbes de polarisation et les regions ou la peinture

  5. The Interrelationship between Marine Biofouling and Cathodic Protection

    DTIC Science & Technology

    1993-01-01

    Vibrio alginolyticus in the laboratory.’ 2 However, after nine hours there were no significant differences in numbers of SRB on polarized and unpolarized...growth of SRB in the sediments surrounding the samples. Fischer conducted laberatory tests in anaerobic, artificial sediments containing SRB. 20 Results...Corrosion Workshop on Microbiological Corrosion, (Sintra, Portugal: 1988), p. 93. 20. K.P. Fischer , Materials Performance 20, 10(1981): p. 41. 21. V.V

  6. Civil Engineering Corrosion Control. Volume 3. Cathodic Protection Design

    DTIC Science & Technology

    1975-02-01

    consequently the output can be varied relatively easily. A change in rectifier output in a prop- erly designed system -will overcome the effects of change ...generally selected long before equipment is assembled for the Job, a sudden change in weather conditions, right-of- way location, or delay in starting may...b. Page 129 - Label anode strings alonag the tank wall as- *TAM AUMD SUIMGS c. Page 140 * paragraph 3. - Change Opruposee. to tpurpose’O d. Umprt

  7. Cathodic Protection of Hot Water Tanks at Fort Sill

    DTIC Science & Technology

    2007-06-01

    should be flat against the material. Bent rivets will fail under stress . Especially note condition of Dee Ring rivets and Dee Ring metal wear pads...free fall distance. Also, to be stressed are the importance of inspections prior to use, the limitations of the equipment, and unique conditions at...devices during the force test; d. Caution statements on critical use limitations; e. Application limits; f. Proper hook -up, anchoring and tie-off

  8. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    SciTech Connect

    Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

    2003-03-31

    This report represents a summary of the work carried out on this project which started October 1999 and ended March 2003. A list of the publications resulting from the work are contained in Appendix A. The most significant achievements are: (1) Dense nanocrystalline zirconia and ceria films were obtained at temperatures < 400 C. (2) Nanocrystalline films of both ceria and zirconia were characterized. (3) We showed that under anodic conditions 0.5 to 1 micron thick nanocrystalline films of Sc doped zirconia have sufficient electronic conductivity to prevent them from being useful as an electrolyte. (4) We have developed a process by which dense 0.5 to 5 micron thick dense films of either YSZ or ceria can be deposited on sintered porous substrates which serve as either the cathode or anode at temperatures as low as 400 C. (5) The program has provided the research to produce two PhD thesis for students, one is now working in the solid oxide fuel cell field. (6) The results of the research have resulted in 69 papers published, 3 papers submitted or being prepared for publication, 50 oral presentations and 3 patent disclosures.

  9. Defocus in cathode lens instruments.

    PubMed

    Tromp, R M; Altman, M S

    2017-02-24

    Accurately measuring defocus in cathode lens instruments (Low Energy Electron Microscopy - LEEM, and Photo Electron Emission Microscopy - PEEM) is a pre-requisite for quantitative image analysis using Fourier Optics (FO) or Contrast Transfer Function (CTF) image simulations. In particular, one must establish a quantitative relation between lens excitation and image defocus. One way to accomplish this is the Real-Space Microspot LEED method, making use of the accurately known angles of diffracted electron beams, and the defocus-dependent shifts of their corresponding real-space images. However, this only works if a sufficiently large number of diffracted beams is available for the sample under investigation. An alternative is to shift the sample along the optical axis by a known distance, and measure the change in objective lens excitation required to re-focus the image. We analytically derive the relation between sample shift and defocus, and apply our results to the measurement and analysis of achromats in an aberration-corrected LEEM instrument.

  10. Manganese Oxide Formation in Lanthanum Strontium Manganite-Yttria-Stabilized Zirconia SOFC Cathodes

    NASA Astrophysics Data System (ADS)

    Wang, Hsiang-Jen; De Guire, Mark R.; Xing, Zhengliang; Agnew, Gerry; Goettler, Richard; Liu, Zhien; Heuer, Arthur H.

    2014-09-01

    Microstructural changes in the cathode adjacent to the cathode-electrolyte interface were studied in SOFCs with lanthanum strontium manganite (LSM)/Y2O3-stabilized ZrO2 (YSZ) composite cathodes after long-term operation (1.3 to 2.0 kh) with steam (1 to 3 pct H2O) added to the cathode gas. We specifically sought to understand why the degradation rate (the increase of area specific resistance with time) was markedly higher at lower temperatures ( e.g., 1073 K (800 °C)) than at higher temperatures ( e.g., 1198 K (925 °C)). Transmission electron microscopy, combined with X-ray energy-dispersive spectroscopy and electron energy-loss spectroscopy, was used to detect and identify submicron MnxOy precipitates. The particles were shown to be Mn3O4 in cells operated at 1198 K (925 °C), and both Mn3O4 and Mn2O3 in cells operated at 1073 K (800 °C). In a cell exposed for 5 kh at 1198 K (925 °C) to a cathode atmosphere of 1.1 pct H2O at 4 bara, MnxOy precipitates were uniformly distributed across the cathode. On the other hand, in an identical cell exposed to the same conditions but operated continuously at 380 mA cm-2, MnxOy precipitates were observed almost exclusively within about 3 µm of the electrolyte/cathode interface. Whether MnxOy formation is causative or simply correlative with the steam effect remains an important question for future work.

  11. Experimental Investigation of Thruster Cathode Physics

    NASA Astrophysics Data System (ADS)

    Crofton, Mark

    2004-11-01

    Advanced ion propulsion technologies are being developed under the Nuclear Electric Xenon Ion System (NEXIS) program for use in outer planet exploration. A revolutionary approach to thruster cathode design is dictated by the very high lifetime and propellant throughput requirements for nuclear electric applications. In conventional dispenser hollow cathodes used in thrusters, processes leading to depletion, inadequate transport, or insufficient production of barium are among those limiting the lifetime. A reservoir hollow cathode is being developed to address each of these failure mechanisms, exploiting four design variables - matrix material, source material, geometry, and thermal design - to essentially eliminate established failure modes. The very long anticipated lifetime necessitates new life validation methods to augment or replace the conventional lifetest approach. One important tool for quickly evaluating design changes is the ability to measure barium density inside a hollow cathode and/or in the plume. The dependence of barium density on temperature and other factors is an extremely important indicator of cathode health, particularly if the ratio Ba:BaO is also obtained. Comparison of barium production for reservoir and conventional cathodes will enable an assessment of the efficacy of reservoir designs and the goal of reducing barium consumption at a given emission current level. This study describes benchmark measurements made on a conventional cathode previously operated in a 20-kW NEXIS laboratory engine. Data on cathode operation and life-limiting processes were obtained through direct, real-time monitoring of atoms and molecules. A high-resolution, tunable laser system was employed to detect absorption of the low-density barium atoms inside the cathode. The plume was monitored also, using a quadrupole mass spectrometer to monitor multiple species and measure ion charge ratios. Data obtained with retarding potential analyzers or other means are

  12. History of Child Welfare and Protection Social Work in Northern Ireland: Finding Continuity amongst Discontinuity in Case Files from 1950 to 1968

    ERIC Educational Resources Information Center

    Skehill, Caroline

    2010-01-01

    This article reports on research carried out on 189 child welfare files from the largest welfare authority in Northern Ireland from 1950 to 1968. The literature review provides a commentary on some of the major debates surrounding child welfare and protection social work from the perspective of its historical development. The report of the…

  13. A new metal-dielectric cathode with long lifetime

    NASA Astrophysics Data System (ADS)

    Wu, Ping; Sun, Jun; Liu, Guozhi; Yang, Zhanfeng; Huo, Shaofei; Liu, Wenyuan

    2017-07-01

    Explosive emission cathodes are widely used in high power microwave generation. Conventional metallic cathodes have the disadvantages of bad emission uniformity and short lifetime. In order to improve the emission property of metallic cathodes, a new metal-dielectric cathode is fabricated with the plasma spraying technology. Unlike previous metal-dielectric cathodes, our metal-dielectric cathode adopts a ferroelectric ceramic which possesses a large permittivity. The results of lifetime experiments show the metal-dielectric cathode presents just slight performance deterioration within 2.5 × 105 pulses and thus has a much longer lifetime than the normal copper cathode. The morphology observation demonstrates that the good emission property of the metal-dielectric cathode may benefit from the appearance of irregularities on the dielectric surface, which will have large microscopic field enhancement factors with the help of large permittivity of the ferroelectric material.

  14. Compact Rare Earth Emitter Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  15. Nanostructured MnO2-Based Cathodes for Li-Ion/Polymer Cells

    NASA Technical Reports Server (NTRS)

    Skandan, Ganesh; Singhal, Amit

    2005-01-01

    Nanostructured MnO2-based cathodes for Li-ion/polymer electrochemical cells have been investigated in a continuing effort to develop safe, high-energy-density, reliable, low-toxicity, rechargeable batteries for a variety of applications in NASA programs and in mass-produced commercial electronic equipment. Whereas the energy densities of state-of-the-art lithium-ion/polymer batteries range from 150 to 175 W h/kg, the goal of this effort is to increase the typical energy density to about 250 W h/kg. It is also expected that an incidental benefit of this effort will be increases in power densities because the distances over which Li ions must diffuse through nanostructured cathode materials are smaller than those through solid bulk cathode materials.

  16. Improved cathode materials for microbial electrosynthesis

    SciTech Connect

    Zhang, T; Nie, HR; Bain, TS; Lu, HY; Cui, MM; Snoeyenbos-West, OL; Franks, AE; Nevin, KP; Russell, TP; Lovley, DR

    2013-01-01

    Microbial electrosynthesis is a promising strategy for the microbial conversion of carbon dioxide to transportation fuels and other organic commodities, but optimization of this process is required for commercialization. Cathodes which enhance electrode-microbe electron transfer might improve rates of product formation. To evaluate this possibility, biofilms of Sporomusa ovata, which are effective in acetate electrosynthesis, were grown on a range of cathode materials and acetate production was monitored over time. Modifications of carbon cloth that resulted in a positive-charge enhanced microbial electrosynthesis. Functionalization with chitosan or cyanuric chloride increased acetate production rates 6-7 fold and modification with 3-aminopropyltriethoxysilane gave rates 3-fold higher than untreated controls. A 3-fold increase in electrosynthesis over untreated carbon cloth cathodes was also achieved with polyaniline cathodes. However, not all strategies to provide positively charged surfaces were successful, as treatment of carbon cloth with melamine or ammonia gas did not stimulate acetate electrosynthesis. Treating carbon cloth with metal, in particular gold, palladium, or nickel nanoparticles, also promoted electrosynthesis, yielding electrosynthesis rates that were 6-,4.7- or 4.5-fold faster than the untreated control, respectively. Cathodes comprised of cotton or polyester fabric treated with carbon nanotubes yielded cathodes that supported acetate electrosynthesis rates that were similar to 3-fold higher than carbon cloth controls. Recovery of electrons consumed in acetate was similar to 80% for all materials. The results demonstrate that one approach to increase rates of carbon dioxide reduction in microbial electrosynthesis is to modify cathode surfaces to improve microbe-electrode interactions.

  17. 2013 Estorm - Invited Paper - Cathode Materials Review

    SciTech Connect

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood III, David L

    2014-01-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403 431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783 789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  18. Multiple cathodic reaction mechanisms in seawater cathodic biofilms operating in sediment microbial fuel cells.

    PubMed

    Babauta, Jerome T; Hsu, Lewis; Atci, Erhan; Kagan, Jeff; Chadwick, Bart; Beyenal, Haluk

    2014-10-01

    In this study, multiple reaction mechanisms in cathodes of sediment microbial fuel cells (SMFCs) were characterized by using cyclic voltammetry and microelectrode measurements of dissolved oxygen and pH. The cathodes were acclimated in SMFCs with sediment and seawater from San Diego Bay. Two limiting current regions were observed with onset potentials of approximately +400 mVAg/AgCl for limiting current I and -120 mVAg/AgCl for limiting current II. The appearance of two catalytic waves suggests that multiple cathodic reaction mechanisms influence cathodic performance. Microscale oxygen concentration measurements showed a zero surface concentration at the electrode surface for limiting current II but not for limiting current I, which allowed us to distinguish limiting current II as the conventional oxygen reduction reaction and limiting current I as a currently unidentified cathodic reaction mechanism. Microscale pH measurements further confirmed these results.

  19. Electricity generation and brewery wastewater treatment from sequential anode-cathode microbial fuel cell.

    PubMed

    Wen, Qing; Wu, Ying; Zhao, Li-xin; Sun, Qian; Kong, Fan-ying

    2010-02-01

    A sequential anode-cathode double-chamber microbial fuel cell (MFC), in which the effluent of anode chamber was used as a continuous feed for an aerated cathode chamber, was constructed in this experiment to investigate the performance of brewery wastewater treatment in conjugation with electricity generation. Carbon fiber was used as anode and plain carbon felt with biofilm as cathode. When hydraulic retention time (HRT) was 14.7 h, a relatively high chemical oxygen demand (COD) removal efficiency of 91.7%-95.7% was achieved under long-term stable operation. The MFC displayed an open circuit voltage of 0.434 V and a maximum power density of 830 mW/m(3) at an external resistance of 300 Omega. To estimate the electrochemical performance of the MFC, electrochemical measurements were carried out and showed that polarization resistance of anode was the major limiting factor in the MFC. Since a high COD removal efficiency was achieved, we conclude that the sequential anode-cathode MFC constructed with bio-cathode in this experiment could provide a new approach for brewery wastewater treatment.

  20. An intermediate-temperature solid oxide fuel cell with electrospun nanofiber cathode

    SciTech Connect

    Zhi, Mingjia; Lee, Shiwoo; Miller, Nicholas; Menzler, Norbert H.; Wu, Nianqiang

    2012-03-22

    Lanthanum strontium cobalt ferrite (LSCF) nanofibers have been fabricated by the electrospinning method and used as the cathode of an intermediate-temperature solid oxide fuel cell (SOFC) with yttria-stabilized zirconia (YSZ) electrolyte. The three-dimensional nanofiber network cathode has several advantages: (i) high porosity; (ii) high percolation; (iii) continuous pathway for charge transport; (iv) good thermal stability at the operating temperature; and (v) excellent scaffold for infiltration. The fuel cell with the monolithic LSCF nanofiber cathode exhibits a power density of 0.90 W cm-2 at 1.9 A cm-2 at 750 °C. The electrochemical performance of the fuel cell has been further improved by infiltration of 20 wt% of gadolinia-doped ceria (GDC) into the LSCF nanofiber cathode. The fuel cell with the LSCF–20% GDC composite cathode shows a power density of 1.07 W cm-2 at 1.9 A cm-2 at 750 °C. The results obtained show that one-dimensional nanostructures such as nanofibers hold great promise as electrode materials for intermediate-temperature SOFCs.

  1. Requirements for long-life operation of inert gas hollow cathodes - Preliminary results

    NASA Technical Reports Server (NTRS)

    Verhey, Timothy R.; Macrae, Gregory S.

    1990-01-01

    An experimental investigation was initiated to establish conditioning procedures for reliable hollow cathode operation via the characterization of critical parameters in a representative cathode test facility. From vacuum pumpdown rates, it was found that approximately 1.5 hours were required to achieve pressure levels within 5 percent of the lowest attainable pressure for this facility, depending on the purge conditions. The facility atmosphere was determined by a residual gas analyzer to be composed of primarily air and water vapor. The effects of vacuum pumping and inert gas purging were evaluated. A maximum effective leakage rate of 2.0 x 10 (exp -3) sccm was observed and its probable causes were examined. An extended test of a 0.64 cm diameter Mo-Re hollow cathode was successfully completed. This test ran for 504 hours at an emission current of 23.0 amperes and a xenon flow rate of 6.1 sccm. Discharge voltage rose continuously from 15 to 21 volts over the course of the test. The temperature of the cathode body during the test was relatively stable at 1160 C. Post-test examination revealed ion-bombardment texturing of the orifice plate to be the only detectable sign of wear on the hollow cathode.

  2. The Monte-Carlo get finished in hollow cathode theory -- a source equation is incoming!

    NASA Astrophysics Data System (ADS)

    Gorin, Vladimir

    2008-10-01

    The hollow cathode effect (HCE) in glow discharge occurred rather hard bean for theoreticians. Classical local Engel and Shtenbek cathode dark space theory does not work under conditions of HCE because it is not possible to neglect inertia of electron here. The electron distribution function has many features and it is far from Maxwellian one. The absence of non-local source model from Paschen invention of a hollow cathode in 1916 till today forced to use Monte-Carlo methods. It meant an absence of any equation for a source of ionization in a hollow cathode! Time to find this equation is coming. It is an integral equation, which is derived from kinetic equation and determines a non-local dependence of ionization source on electric field through phase trajectories of electron motion. When simplification of local dependence is possible, the equation can be transformed into ordinary differential equation and then it is coincident with a continuity equation of classical Engel-Shtenbek model. In joining with field equations the source equation enables to calculate current voltage characteristics of simple glow and hollow cathode discharge and see the HCE in mathematical simulation.

  3. Requirements for long-life operation of inert gas hollow cathodes: Preliminary report

    NASA Technical Reports Server (NTRS)

    Verhey, Timothy R.; Macrae, Gregory S.

    1990-01-01

    An experimental investigation was initiated to establish conditioning procedures for reliable hollow cathode operation via the characterization of critical parameters in a representative cathode test facility. From vacuum pumpdown rates, it was found that approximately 1.5 hours were required to achieve pressure levels within 5 percent of the lowest attainable pressure for this facility, depending on the purge conditions. The facility atmosphere was determined by a residual gas analyzer to be composed of primarily air and water vapor. The effects of vacuum pumping and inert gas purging were evaluated. A maximum effective leakage rate of 2.0 x 10(exp -3)sccm was observed and its probable causes were examined. An extended test of a 0.64 cm diameter Mo-Re hollow cathode was successfully completed. This test ran for 504 hours at an emission current of 23.0 amperes and a xenon flow rate of 6.1 sccm. Discharge voltage rose continuously from 15 to 21 volts over the course of the test. The temperature of the cathode body during the test was relatively stable at 1160 C. Post-test examination revealed ion-bombardment texturing of the orifice plate to be the only detectable sign of wear on the hollow cathode.

  4. Remote Monitoring of Cathodic Protection and Cathodic Protection System Upgrades for Tanks and Pipelines at Fort Carson

    DTIC Science & Technology

    2007-06-01

    ground Test Station is greater than 1,000 feet. • Powered by a Field Replaceable long life A-size lithium – thionyl chloride cell with an expected life...will send back all of the stored voltage readings and the current internal Lithium battery voltage. • The wireless RF link uses the North American...a receiving unit. This concept was chosen because it can use a long-life battery power source for the measuring and transmitting functions and

  5. Power-Efficient, High-Current-Density, Long-Life Thermionic Cathode Developed for Microwave Amplifier Applications

    NASA Technical Reports Server (NTRS)

    Wintucky, Edwin G.

    2002-01-01

    A power-efficient, miniature, easily manufactured, reservoir-type barium-dispenser thermionic cathode has been developed that offers the significant advantages of simultaneous high electron-emission current density (>2 A/sq cm) and very long life (>100,000 hr of continuous operation) when compared with the commonly used impregnated-type barium-dispenser cathodes. Important applications of this cathode are a wide variety of microwave and millimeter-wave vacuum electronic devices, where high output power and reliability (long life) are essential. We also expect it to enable the practical development of higher purveyance electron guns for lower voltage and more reliable device operation. The low cathode heater power and reduced size and mass are expected to be particularly beneficial in traveling-wave-tube amplifiers (TWTA's) for space communications, where future NASA mission requirements include smaller onboard spacecraft systems, higher data transmission rates (high frequency and output power) and greater electrical efficiency.

  6. Studies on an experimental quartz tube hollow cathode

    NASA Technical Reports Server (NTRS)

    Siegfried, D. E.; Wilbur, P. J.

    1979-01-01

    An experimental study is described in which a quartz tube, hollow cathode was operated in a test fixture allowing the simultaneous measurement of internal cathode pressure, insert temperature profiles, and the emission currents from various cathode components as a function of discharge current and propellant (mercury) mass flow rate for a number of different cathode orifice diameters. Results show that the insert temperature profile is essentially independent of orifice diameter but depends strongly on internal cathode pressure and emission current. The product of internal cathode pressure and insert diameter is shown to be important in determining the emission location and the minimum keeper voltage.

  7. Use of Both Anode and Cathode Reactions in Wastewater Treatment

    NASA Astrophysics Data System (ADS)

    Brillas, Enric; Sirés, Ignasi; Cabot, Pere LluíS.

    Here, we describe the fundamentals, laboratory experiments, and environmental applications of indirect electrooxidation methods based on H2O2 electrogeneration such as electro-Fenton, photoelectro-Fenton and peroxicoagulation for the treatment of acidic wastewaters containing toxic and recalcitrant organics. These methods are electrochemical advanced oxidation processes that can be used in divided and undivided electrolytic cells in which pollutants are oxidized by hydroxyl radical (•OH) produced from anode and/or cathode reactions. H2O2 is generated from the two-electron reduction of O2 at reticulated vitreous carbon, graphite, carbon-felt, and O2-diffusion cathodes. The most usual method is electro-Fenton where Fe2 + added to the wastewater reacts with electrogenerated H2O2 to yield •OH and Fe3 + from Fenton's reaction. An advantage of this technique is that Fe2 + is continuously regenerated from cathodic reduction of Fe3 +. The characteristics of different electro-Fenton systems where pollutants are simultaneously destroyed by •OH formed in the medium from Fenton's reaction and at the anode surface from water oxidation are explained. The effect of the anode [Pt or boron-doped diamond (BDD)] and cathode (carbon-felt or O2-diffusion) on the degradation rate of persistent industrial by-products, herbicides, pharmaceuticals, dyes, etc. is examined. Initial pollutants react much more rapidly with •OH formed in the medium and their degradation sequences are discussed from aromatic intermediates and finally short aliphatic acids are detected. The synergetic positive catalytic effect of Cu2 + on the electro-Fenton process is evidenced. The photoelectro-Fenton method involves the irradiation of the wastewater with UVA light that rapidly photodecomposes complexes of Fe3 + with final carboxylic acids enhancing total decontamination. The peroxicoagulation method uses a sacrificial Fe anode that is continuously oxidized to Fe2 + and organics are either mineralized

  8. Hot-cathode preionization studies in CCT

    SciTech Connect

    Darrow, D.S.; Ono, M. . Plasma Physics Lab.); Pribyl, P.A.; Taylor, R.J. . Tokamak Fusion Lab.)

    1991-07-01

    A hot LaB{sub 6} cathode was used to ionize the gas in the vessel of CCT at the start of tokamak discharges. Substantial plasma densities could be obtained in the preionization phase, resulting in reliable breakdown and initiation of q{sub a} {approx equal} 3 discharges at loop voltages of 4.2 V/turn, considerably lower than the 33 V/turn required with no preionization and the 20 V/turn required when a 15 kHz oscillator was the preionization source. When inductive effects were subtracted, the cathode preionization produced a loop voltage attributable to plasma resistance of 4 V/turn, while the oscillator-produced plasma required 12 V/turn. Repeatable cathode-enhanced breakdowns could be obtained at voltages as low as 3.4 V/turn for discharges with higher q{sub a}. With the cathode-enhanced plasma, the initial value of dI{sub p}/d{Phi}{sub OH} is higher than that with the oscillator-produced plasma. The spectrum of visible light emitted from cathode-initiated discharges shows no additional impurities present beyond those seen in a normal plasma. 10 refs., 4 figs.

  9. RHETT/EPDM Flight Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Manzella, David; Patterson, Michael; Pastel, Michael

    1997-01-01

    Under the sponsorship of the BMDO Russian Hall Electric Thruster Technology program two xenon hollow cathodes, a flight unit and a flight spare were fabricated, acceptance tested and delivered to the Naval Research Laboratory for use on the Electric Propulsion Demonstration Module. These hollow cathodes, based on the International Space Station plasma contactor design, were fabricated at the NASA Lewis Research Center for use with a D-55 anode layer thruster in the first on-orbit operational application of this technology. The 2.2 Ampere nominal emission current of this device was obtained with a xenon flow rate of 0.6 mg/s. Ignition of the cathode discharge was accomplished through preheating the active electron emitter with a resistive heating element before application of a 650 volt ignition pulse between the emitter and an external starting electrode. The successful acceptance testing of the Electric Propulsion Demonstration Module utilizing these cathodes demonstrated the suitability of cathodes based on barium impregnated inserts in an enclosed keeper configuration for use with Hall thruster propulsion systems.

  10. Spindt cold cathode electron gun development program

    NASA Technical Reports Server (NTRS)

    Spindt, C. A.

    1983-01-01

    A thin film field emission cathode array and an electron gun based on this emitter array are summarized. Fabricating state of the art cathodes for testing at NASA and NRL, advancing the fabrication technology, developing wedge shaped emitters, and performing emission tests are covered. An anistropic dry etching process (reactive ion beam etching) developed that leads to increasing the packing density of the emitter tips to about 5 x 10 to the 6th power/square cm. Tests with small arrays of emitter tips having about 10 tips has demonstrated current densities of over 100 A/sq cm. Several times using cathodes having a packing density of 1.25 x 10 to the 6th power tips/sq cm. Indications are that the higher packing density achievable with the dry etch process may extend this capability to the 500 A/sq cm range and beyond. The wedge emitter geometry was developed and shown to produce emission. This geometry can (in principle) extend the current density capability of the cathodes beyond the 500 A/sq cm level. An emission microscope was built and tested for use with the cathodes.

  11. Comparison of hollow cathode discharge plasma configurations

    NASA Astrophysics Data System (ADS)

    Farnell, Casey C.; Williams, John D.; Farnell, Cody C.

    2011-04-01

    Hollow cathodes used in plasma contactor and electric propulsion devices provide electrons for sustaining plasma discharges and enabling plasma bridge neutralization. Life tests show erosion on hollow cathodes exposed to the plasma environment produced in the region downstream of these devices. To explain the observed erosion, plasma flow field measurements are presented for hollow cathode generated plasmas using both directly immersed probes and remotely located plasma diagnostics. Measurements on two cathode discharge configurations are presented: (1) an open, no magnetic field configuration and (2) a setup simulating the discharge chamber environment of an ion thruster. In the open cathode configuration, large amplitude plasma potential oscillations, ranging from 20 to 85 V within a 34 V discharge, were observed using a fast response emissive probe. These oscillations were observed over a dc potential profile that included a well-defined potential hill structure. A remotely located electrostatic analyzer (ESA) was used to measure the energy of ions produced within the plasma, and energies were detected that met, and in some cases exceeded, the peak oscillatory plasma potentials detected by the emissive probe. In the ion thruster discharge chamber configuration, plasma potentials from the emissive probe again agreed with ion energies recorded by the remotely located ESA; however, much lower ion energies were detected compared with the open configuration. A simplified ion-transit model that uses temporal and spatial plasma property measurements is presented and used to predict far-field plasma streaming properties. Comparisons between the model and remote measurements are presented.

  12. Investigations Of A Pulsed Cathodic Vacuum Arc

    NASA Astrophysics Data System (ADS)

    Oates, T. W. H.; Pigott, J.; Denniss, P.; Mckenzie, D. R.; Bilek, M. M. M.

    2003-06-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed.

  13. The study of the varying characteristics of cathodic regions for defective coating in 3.5% sodium chloride solution by EIS and WBE

    NASA Astrophysics Data System (ADS)

    Wang, Haijie; Wang, Jia; Wang, Wei; Zhang, Wei

    2015-04-01

    The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode (WBE). The electrochemical impedance spectroscopy (EIS) of the WBE was carried out to analyze the performance of coating delamination and corrosion behavior of carbon steel beneath defective coating. The EIS data revealed that protective capability of coating decreased with immersion time and the degree of cathodic delamination showed a rapid rise. The current density distribution of WBE indicated that cathodic sites was located at the defect at the beginning of immersion and gradually spread into the intact coating. The cathodic regions were distinguished from the anodic area and distributed over the WBE. The changes of cathodic sites could reflect the deterioration process of defective coating. The cathodic area ratio was a more useful parameter than the cathodic delamination degree to evaluate the coating cathodic delamination. The polarity reversals of electrodes at the defect and beneath coating were observed. A simple discussion of relationship between the blister and the polarity reversal was made from a standpoint of electrochemical distribution. WBE method was able to map and record the changes of local cathodic sites beneath defective coating in real time, which could provide more detailed information about the local degradation of coating.

  14. Energy savings through the use of an improved aluminum reduction-cell cathode. Technical progress report, April 1, 1980-June 30, 1980

    SciTech Connect

    Dorward, R.C.; Payne, J.R.

    1980-08-05

    Goal is to develop a Hall cell cathode, which will reduce the specific energy consumption of existing commercial cells by 20 to 25%. Basis of the improvement is the utilization of titanium diboride (TiB/sub 2/), a material that is wetted by molten aluminum, as the cell cathode. This provides a stable cathode surface, thereby allowing the cell to be operated at a smaller anode-cathode distance (ACD). Energy savings arise as a result of reduced resistive losses through the cryolite electrolyte. This phase of the program is comprised of three integrated parts: (1) materials characterization, (2) pilot cell testing, and (3) a full-sized cell demonstration. During this quarter emphasis continued on rebuilding the 15KA pilot cell to accommodate a highly sloped electrode system. TiB/sub 2/ cathode materials were received, and construction of cell components and peripheral equipment was completed.

  15. MoO3 Cathodes for High-Temperature Lithium Thin-Film Cells

    NASA Technical Reports Server (NTRS)

    West, William; Whitacre, Jay

    2007-01-01

    MoO3 has shown promise as a cathode material that can extend the upper limit of operating temperature of rechargeable lithium thin-film electrochemical cells. Cells of this type are undergoing development for use as energy sources in cellular telephones, wireless medical sensors, and other, similarly sized portable electronic products. The LiCoO2 and LiMn2O4 cathodes heretofore used in these cells exhibit outstanding cycle lives (of the order of hundreds of thousands of cycles) at room temperature, but operation at higher temperatures reduces their cycle lives substantially: for example, at a temperature of 150 C, cells containing LiCoO2 cathodes lose half their capacities in 100 charge/discharge cycles. The superiority of MoO3 as a cathode material was demonstrated in experiments on lithium thin-film cells fabricated on glass slides. Each cell included a layer of Ti (for adhesion to the glass slide), a patterned layer of Pt that served as a cathode current collector, a cathode layer of MoO3, a solid electrolyte layer of Li3.3 PO3.8 N0.22 ("LiPON"), and an anode layer of Li. All the layers were deposited by magnetron sputtering except for the Li layer, which was deposited by thermal evaporation. These cells, along with similar ones containing LiCoO2 cathodes, were subjected to several tests, including measurements of specific capacity in charge/discharge cycling at a temperature of 150 C. The results of these measurements, plotted in the figure, showed that whereas specific capacity of the cells containing LiCoO2 cathodes faded to about half its initial value after only 100 cycles, the specific capacity of the cells containing the MoO3 cathodes faded only slightly during the first few hundred cycles and thereafter not only recovered to its initial value but continued to increase up to at least 5,500 cycles.

  16. Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

    PubMed Central

    Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

    2017-01-01

    Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries. PMID:28443608

  17. Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

    2017-04-01

    Undesired electrode-electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.

  18. Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

    DOE PAGES

    Li, Wangda; Dolocan, Andrei; Oh, Pilgun; ...

    2017-04-26

    Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species.more » By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Finally, our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.« less

  19. Compatible interface design of CoO-based Li-O2 battery cathodes with long-cycling stability

    PubMed Central

    Shang, Chaoqun; Dong, Shanmu; Hu, Pu; Guan, Jing; Xiao, Dongdong; Chen, Xiao; Zhang, Lixue; Gu, Lin; Cui, Guanglei; Chen, Liquan

    2015-01-01

    Lithium-oxygen batteries with high theoretical energy densities have great potential. Recent studies have focused on different cathode architecture design to address poor cycling performance, while the impact of interface stability on cathode side has been barely reported. In this study, we introduce CoO mesoporous spheres into cathode, where the growth of crystalline discharge products (Li2O2) is directly observed on the CoO surface from aberration-corrected STEM. This CoO based cathode demonstrates more than 300 discharge/charge cycles with excessive lithium anode. Under deep discharge/charge, CoO cathode exhibited superior cycle performance than that of Co3O4 with similar nanostructure. This improved cycle performance can be ascribed to a more favorable adsorption configuration of Li2O2 intermediates (LiO2) on CoO surface, which is demonstrated through DFT calculation. The favorable adsorption of LiO2 plays an important role in the enhanced cycle performance, which reduced the contact of LiO2 to carbon materials and further alleviated the side reactions during charge process. This compatible interface design may provide an effective approach in protecting carbon-based cathodes in metal-oxygen batteries. PMID:25720845

  20. Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries.

    PubMed

    Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

    2017-04-26

    Undesired electrode-electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.

  1. Compatible interface design of CoO-based Li-O2 battery cathodes with long-cycling stability.

    PubMed

    Shang, Chaoqun; Dong, Shanmu; Hu, Pu; Guan, Jing; Xiao, Dongdong; Chen, Xiao; Zhang, Lixue; Gu, Lin; Cui, Guanglei; Chen, Liquan

    2015-02-27

    Lithium-oxygen batteries with high theoretical energy densities have great potential. Recent studies have focused on different cathode architecture design to address poor cycling performance, while the impact of interface stability on cathode side has been barely reported. In this study, we introduce CoO mesoporous spheres into cathode, where the growth of crystalline discharge products (Li2O2) is directly observed on the CoO surface from aberration-corrected STEM. This CoO based cathode demonstrates more than 300 discharge/charge cycles with excessive lithium anode. Under deep discharge/charge, CoO cathode exhibited superior cycle performance than that of Co3O4 with similar nanostructure. This improved cycle performance can be ascribed to a more favorable adsorption configuration of Li2O2 intermediates (LiO2) on CoO surface, which is demonstrated through DFT calculation. The favorable adsorption of LiO2 plays an important role in the enhanced cycle performance, which reduced the contact of LiO2 to carbon materials and further alleviated the side reactions during charge process. This compatible interface design may provide an effective approach in protecting carbon-based cathodes in metal-oxygen batteries.

  2. Advanced rechargeable sodium batteries with novel cathodes

    NASA Technical Reports Server (NTRS)

    Di Stefano, S.; Ratnakumar, B. V.; Bankston, C. P.

    1990-01-01

    Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 W h/kg theoretical). Energy densities in excess of 180 W h/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Various new cathode materials are presently being evaluated for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far, the studies have focussed on alternative metal chlorides such as CuCl2 and organic cathode materials such as TCNE.

  3. Advanced rechargeable sodium batteries with novel cathodes

    NASA Technical Reports Server (NTRS)

    Distefano, S.; Ratnakumar, B. V.; Bankston, C. P.

    1989-01-01

    Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Researchers at JPL are evaluating various new cathode materials for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far studies have focused on alternate metal chlorides such as CuCl2 and organic cathode materials such as tetracyanoethylene (TCNE).

  4. Field free, directly heated lanthanum boride cathode

    DOEpatents

    Leung, Ka-Ngo; Moussa, D.; Wilde, S.B.

    1987-02-02

    A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic field which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

  5. Field free, directly heated lanthanum boride cathode

    DOEpatents

    Leung, Ka-Ngo; Moussa, David; Wilde, Stephen B.

    1991-01-01

    A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic fields which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

  6. Advanced rechargeable sodium batteries with novel cathodes

    NASA Technical Reports Server (NTRS)

    Di Stefano, S.; Ratnakumar, B. V.; Bankston, C. P.

    1990-01-01

    Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 W h/kg theoretical). Energy densities in excess of 180 W h/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Various new cathode materials are presently being evaluated for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far, the studies have focussed on alternative metal chlorides such as CuCl2 and organic cathode materials such as TCNE.

  7. Filtered cathodic arc deposition apparatus and method

    DOEpatents

    Krauss, Alan R.

    1999-01-01

    A filtered cathodic arc deposition method and apparatus for the production of highly dense, wear resistant coatings which are free from macro particles. The filtered cathodic arc deposition apparatus includes a cross shaped vacuum chamber which houses a cathode target having an evaporable surface comprised of the coating material, means for generating a stream of plasma, means for generating a transverse magnetic field, and a macro particle deflector. The transverse magnetic field bends the generated stream of plasma in the direction of a substrate. Macro particles are effectively filtered from the stream of plasma by traveling, unaffected by the transverse magnetic field, along the initial path of the plasma stream to a macro particle deflector. The macro particle deflector has a preformed surface which deflects macro particles away from the substrate.

  8. Use of Continuous Plankton Recorder information in support of marine management: applications in fisheries, environmental protection, and in the study of ecosystem response to environmental change [review article

    NASA Astrophysics Data System (ADS)

    Brander, K. M.; Dickson, R. R.; Edwards, M.

    2003-08-01

    The Continuous Plankton Recorder (CPR) survey was conceived from the outset as a programme of applied research designed to assist the fishing industry. Its survival and continuing vigour after 70 years is a testament to its utility, which has been achieved in spite of great changes in our understanding of the marine environment and in our concerns over how to manage it. The CPR has been superseded in several respects by other technologies, such as acoustics and remote sensing, but it continues to provide unrivalled seasonal and geographic information about a wide range of zooplankton and phytoplankton taxa. The value of this coverage increases with time and provides the basis for placing recent observations into the context of long-term, large-scale variability and thus suggesting what the causes are likely to be. Information from the CPR is used extensively in judging environmental impacts and producing quality status reports (QSR); it has shown the distributions of fish stocks, which had not previously been exploited; it has pointed to the extent of ungrazed phytoplankton production in the North Atlantic, which was a vital element in establishing the importance of carbon sequestration by phytoplankton. The CPR continues to be the principal source of large-scale, long-term information about the plankton ecosystem of the North Atlantic. It has recently provided extensive information about the biodiversity of the plankton and about the distribution of introduced species. It serves as a valuable example for the design of future monitoring of the marine environment and it has been essential to the design and implementation of most North Atlantic plankton research.

  9. A Chemical-Adsorption Strategy to Enhance the Reaction Kinetics of Lithium-Rich Layered Cathodes via Double-Shell Surface Modification.

    PubMed

    Guo, Lichao; Li, Jiajun; Cao, Tingting; Wang, Huayu; Zhao, Naiqin; He, Fang; Shi, Chunsheng; He, Chunnian; Liu, Enzuo

    2016-09-21

    Sluggish surface reaction kinetics hinders the power density of Li-ion battery. Thus, various surface modification techniques have been applied to enhance the electronic/ionic transfer kinetics. However, it is challenging to obtain a continuous and uniform surface modification layer on the prime particles with structure integration at the interface. Instead of classic physical-adsorption/deposition techniques, we propose a novel chemical-adsorption strategy to synthesize double-shell modified lithium-rich layered cathodes with enhanced mass transfer kinetics. On the basis of experimental measurement and first-principles calculation, MoO2S2 ions are proved to joint the layered phase via chemical bonding. Specifically, the Mo-O or Mo-S bonds can flexibly rotate to bond with the cations in the layered phase, leading to the good compatibility between the thiomolybdate adsorption layer and layered cathode. Followed by annealing treatment, the lithium-excess-spinel inner shell forms under the thiomolybdate adsorption layer and functions as favorable pathways for lithium and electron. Meanwhile, the nanothick MoO3-x(SO4)x outer shell protects the transition metal from dissolution and restrains electrolyte decomposition. The double-shell modified sample delivers an enhanced discharge capacity almost twice as much as that of the unmodified one at 1 A g(-1) after 100 cycles, demonstrating the superiority of the surface modification based on chemical adsorption.

  10. Synchrotron Investigations of SOFC Cathode Degradation

    SciTech Connect

    Idzerda, Yves

    2013-09-30

    The atomic variations occurring in cathode/electrolyte interface regions of La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3-δ} (LSCF) cathodes and other SOFC related materials have been investigated and characterized using soft X-ray Absorption Spectroscopy (XAS) and diffuse soft X-ray Resonant Scattering (XRS). X-ray Absorption Spectroscopy in the soft X-ray region (soft XAS) is shown to be a sensitive technique to quantify the disruption that occurs and can be used to suggest a concrete mechanism for the degradation. For LSC, LSF, and LSCF films, a significant degradation mechanism is shown to be Sr out-diffusion. By using the XAS spectra of hexavalent Cr in SrCrO4 and trivalent Cr in Cr2O3, the driving factor for Sr segregation was identified to be the oxygen vacancy concentration at the anode and cathode side of of symmetric LSCF/GDC/LSCF heterostructures. This is direct evidence of vacancy induced cation diffusion and is shown to be a significant indicator of cathode/electrolyte interfacial degradation. X-ray absorption spectroscopy is used to identify the occupation of the A-sites and B-sites for LSC, LSF, and LSCF cathodes doped with other transition metals, including doping induced migration of Sr to the anti-site for Sr, a significant cathode degradation indicator. By using spatially resolved valence mapping of Co, a complete picture of the surface electrochemistry can be determined. This is especially important in identifying degradation phenomena where the degradation is spatially localized to the extremities of the electrochemistry and not the average. For samples that have electrochemical parameters that are measured to be spatially uniform, the Co valence modifications were correlated to the effects of current density, overpotential, and humidity.

  11. High pressure working mode of hollow cathode arc discharges

    NASA Technical Reports Server (NTRS)

    Minoo, H.; Popovici, C.

    1985-01-01

    The behavior of high pressure cathotrons is discussed. Methods of preheating either the gas or the cathode itself are detailed together with various geometries for the hollow cathode. Three special configurations were tested, and the results are analyzed.

  12. Review on MIEC Cathode Materials for Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Burnwal, Suman Kumar; Bharadwaj, S.; Kistaiah, P.

    2016-11-01

    The cathode is one of the most important components of solid oxide fuel cells (SOFCs). The reduction of oxygen at the cathode (traditional cathodes like LSM, LSGM, etc.) is the slow step in the cell reaction at intermediate temperature (600-800∘C) which is one of the key obstacles to the development of SOFCs. The mixed ionic and electronic conducting cathode (MIEC) like LSCF, BSCF, etc., has recently been proposed as a promising cathode material for SOFC due to the improvement of the kinetic of the cathode reaction. The MIEC materials provide not only the electrons for the reduction of oxygen, but also the ionic conduction required to ensure the transport of the formed oxygen ions and thereby improves the overall electrochemical performance of SOFC system. The characteristics of MIEC cathode materials and its comparison with other traditional cathode materials is studied and presented in the paper.

  13. High reliability cathode heaters for ion thrusters

    NASA Technical Reports Server (NTRS)

    Mueller, L. A.

    1976-01-01

    A number of space missions were proposed which utilize 30-cm mercury bombardment ion thrusters and also require a large number of thruster restarts. A test program was carried out to determine thermal cycle life of several different cathode heater designs. Plasma/flame sprayed heaters and swaged type heaters were tested. Four of the five plasma/flame sprayed heaters tested failed in a comparatively short time. Four tantalum swaged heaters that were brazed to the tantalum cathode tube were successfully tested and met the goals that were set at the start of the test.

  14. Investigation and improvement of SOFC composite cathodes

    NASA Astrophysics Data System (ADS)

    Bidrawn, Fred

    The focus of this dissertation is on the preparation, performance, and long term stability of SOFC composite cathodes prepared by infiltration methods. The majority of the work that follows aims to improve the understanding of the processes contributing to cathode deactivation and to propose strategies to lessen the extent of this deactivation. Through this understanding of the factors governing cathode performance, improvements can be made in overall cathode performance which can in turn lead to lower operating temperatures. The fuel cells used in this work were prepared by tapecasting and infiltration methods. Composite YSZ-perovskite electrodes were prepared by infiltration of stoichiometric ratios of perovskite precursor nitrate salts into a porous YSZ scaffold. First, the influence of ionic conductivity on the performance of solid oxide fuel cell cathodes was studied for electrodes prepared by infiltration of 40-wt% La0.8Ca0.2FeO3 (LCF), La0.8 Sr0.2FeO3 (LSF), and La0.8Ba0.2 FeO3 (LBF) into porous YSZ scaffolds. Although ionic conductivity varied by over an order of magnitude, no significant difference was observed in the performance of each material, suggesting that oxygen ion diffusion through perovskite film is not a rate limiting step for the oxygen reduction process within the cathode. Next, the effect of various infiltrated dopants on the performance of SOFC cathodes was examined. The addition of dopants had little influence on the 1123-K composite electrodes but all dopants tested improved the performance of the 1373-K, suggesting that the improved performance is related to structural changes in the electrode, rather than to improved catalytic properties or ionic conductivity. Based on these results, a model was developed to understand the performance of these electrodes. Two rate-limiting cases are considered for oxygen transfer into the YSZ fins: diffusion through the perovskite film or reactive adsorption of O2 at the perovskite surface. In agreement

  15. Engineering-Scale Liquid Cadmium Cathode Experiments

    SciTech Connect

    D Vaden; B. R. Westphal; S. X. Li; T. A. Johnson; K. B. Davies; D. M. Pace

    2006-08-01

    Recovery of transuranic actinides (TRU) using electrorefining is a process being investigated as part of the Department of Energy (DOE) Advanced Fuel Cycle Initiative (AFCI). TRU recovery via electrorefining onto a solid cathode is very difficult as the thermodynamic properties of transuranics are not favourable for them to remain in the metal phase while significant quantities of uranium trichloride exist in the electrolyte. Theoretically, the concentration of transuranics in the electrolyte must be approximately 106 greater than the uranium concentration in the electrolyte to produce a transuranic deposit on a solid cathode. Using liquid cadmium as a cathode contained within a LiCl-KCl eutectic salt, the co-deposition of uranium and transuranics is feasible because the activity of the transuranics in liquid cadmium is very small. Depositing transuranics and uranium in a liquid cadmium cathode (LCC) theoretically requires the concentration of transuranics to be two to three times the uranium concentration in the electrolyte. Three LCC experiments were performed in an Engineering scale elecdtrorefiner, which is located in the argon hot cell of the Fuel Conditioning Facility at the Materials and Fuels Complex on the Idaho National Laboratory. Figure 1 contains photographs of the LCC assembly in the hot cell prior to the experiment and a cadmium ingot produced after the first LCC test. Figure 1. Liquid Cadmium Cathode (left) and Cadmium Ingot (right) The primary goal of the engineering-scale liquid cadmium cathode experiments was to electrochemically collect kilogram quantities of uranium and plutonium via a LCC. The secondary goal was to examine fission product contaminations in the materials collected by the LCC. Each LCC experiment used chopped spent nuclear fuel from the blanket region of the Experimental Breeder Reactor II loaded into steel baskets as the anode with the LCC containing 26 kg of cadmium metal. In each experiment, between one and two kilograms of

  16. Ferroelectric Cathodes in Transverse Magnetic Fields

    SciTech Connect

    Alexander Dunaevsky; Yevgeny Raitses; Nathaniel J. Fisch

    2002-07-29

    Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode.

  17. /C Composite Cathode for Li Ion Battery

    NASA Astrophysics Data System (ADS)

    Wang, Shulan; Liu, Xuan; Li, Huiqing; Li, Li

    2014-12-01

    Li3V2(PO4)3/C composites were prepared at different temperatures and assembled as cathodes for Li ion batteries. Their structure and electrochemical properties were properly characterized. The internal and charge transfer resistance of the Li3V2(PO4)3/C cathodes were obtained by simulating the ac impedance spectra with equivalent circuits. The Li3V2(PO4)3/C composite sintered at 1123 K (850 °C) exhibits excellent electrochemical performances because of its smaller internal resistance and charge transfer resistance, as well as faster Li ion inserting/extracting rates.

  18. Cathode architectures for alkali metal / oxygen batteries

    DOEpatents

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  19. High reliability cathode heaters for ion thrusters

    NASA Technical Reports Server (NTRS)

    Mueller, L. A.

    1976-01-01

    A number of space missions have been proposed which will utilize 30-cm mercury bombardment ion thrusters and also will require a large number of thruster restarts. A test program was carried out to determine thermal cycle life of several different cathode heater designs. Plasma/flame sprayed heaters and swaged type heaters were tested. Four of the five plasma/flame sprayed heaters tested failed in a comparatively short time. Four tantalum swaged heaters that were brazed to the tantalum cathode tube were successfully tested and met the goals that were set at the start of the test.

  20. Fabrication Of Metal Chloride Cathodes By Sintering

    NASA Technical Reports Server (NTRS)

    Bugga, Ratnakumar V.; Di Stefano, Salvador; Bankston, C. Perry

    1992-01-01

    Transition-metal chloride cathodes for use in high-temperature rechargeable sodium batteries prepared by sintering transition-metal powders mixed with sodium chloride. Need for difficult and dangerous chlorination process eliminated. Proportions of transition metal and sodium chloride in mixture adjusted to suit specific requirements. Cathodes integral to sodium/metal-chloride batteries, which have advantages over sodium/sulfur batteries including energy densities, increased safety, reduced material and thermal-management problems, and ease of operation and assembly. Being evaluated for supplying electrical power during peak demand and electric vehicles.

  1. MPD arcjet cathode surface current density

    NASA Astrophysics Data System (ADS)

    Sheshadri, T. S.

    1991-08-01

    The radial current density distribution on the cathodic longitudinal surface of magnetoplasmadynamic arcjets for axisymmetric geometries has been obtained by simultaneous solution of the electromagnetic equations for a given uniform gas dynamic field. The solution for the current density distribution displays current concentrations at two locations, that is, at the upstream and downstream ends of the cathode. This result is in conformity with known experimental data. The parameters responsible for these current concentrations are identified. It is shown that the effect of the magnetic Reynolds number on the current density distribution is different depending on whether or not the Hall effect is included.

  2. Fabrication Of Metal Chloride Cathodes By Sintering

    NASA Technical Reports Server (NTRS)

    Bugga, Ratnakumar V.; Di Stefano, Salvador; Bankston, C. Perry

    1992-01-01

    Transition-metal chloride cathodes for use in high-temperature rechargeable sodium batteries prepared by sintering transition-metal powders mixed with sodium chloride. Need for difficult and dangerous chlorination process eliminated. Proportions of transition metal and sodium chloride in mixture adjusted to suit specific requirements. Cathodes integral to sodium/metal-chloride batteries, which have advantages over sodium/sulfur batteries including energy densities, increased safety, reduced material and thermal-management problems, and ease of operation and assembly. Being evaluated for supplying electrical power during peak demand and electric vehicles.

  3. Hollow-Cathode Source Generates Plasma

    NASA Technical Reports Server (NTRS)

    Deininger, W. D.; Aston, G.; Pless, L. C.

    1989-01-01

    Device generates argon, krypton, or xenon plasma via thermionic emission and electrical discharge within hollow cathode and ejects plasma into surrounding vacuum. Goes from cold start up to full operation in less than 5 s after initial application of power. Exposed to moist air between operations without significant degradation of starting and running characteristics. Plasma generated by electrical discharge in cathode barrel sustained and aided by thermionic emission from emitter tube. Emitter tube does not depend on rare-earth oxides, making it vulnerable to contamination by exposure to atmosphere. Device modified for use as source of plasma in laboratory experiments or industrial processes.

  4. DARHT 2 kA Cathode Development

    SciTech Connect

    Henestroza, E.; Houck, T.; Kwan, J.W.; Leitner, M.; Miram, G.; Prichard, B.; Roy, P.K.; Waldron, W.; Westenskow, G.; Yu, S.; Bieniosek, F.M.

    2009-03-09

    In the campaign to achieve 2 kA of electron beam current, we have made several changes to the DARHT-II injector during 2006-2007. These changes resulted in a significant increase in the beam current, achieving the 2 kA milestone. Until recently (before 2007), the maximum beam current that was produced from the 6.5-inch diameter (612M) cathode was about 1300 A when the cathode was operating at a maximum temperature of 1140 C. At this temperature level, the heat loss was dominated by radiation which is proportional to temperature to the fourth power. The maximum operating temperature was limited by the damage threshold of the potted filament and the capacity of the filament heater power supply, as well as the shortening of the cathode life time. There were also signs of overheating at other components in the cathode assembly. Thus it was clear that our approach to increase beam current could not be simply trying to run at a higher temperature and the preferred way was to operate with a cathode that has a lower work function. The dispenser cathode initially used was the type 612M made by SpectraMat. According to the manufacturer's bulletin, this cathode should be able to produce more than 10 A/cm{sup 2} of current density (corresponding to 2 kA of total beam current) at our operating conditions. Instead the measured emission (space charge limited) was 6 A/cm{sup 2}. The result was similar even after we had revised the activation and handling procedures to adhere more closely to the recommend steps (taking longer time and nonstop to do the out-gassing). Vacuum was a major concern in considering the cathode's performance. Although the vacuum gauges at the injector vessel indicated 10{sup -8} Torr, the actual vacuum condition near the cathode in the central region of the vessel, where there might be significant out-gassing from the heater region, was never determined. Poor vacuum at the surface of the cathode degraded the emission (by raising the work function value). We

  5. A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.

    PubMed

    Gütz, Christoph; Selt, Maximilian; Bänziger, Markus; Bucher, Christoph; Römelt, Christina; Hecken, Nadine; Gallou, Fabrice; Galvão, Tomás R; Waldvogel, Siegfried R

    2015-09-28

    Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives.

  6. Plasma-Surface Interactions in Hollow Cathode Discharges for Electric Propulsion

    NASA Astrophysics Data System (ADS)

    Capece, Angela Maria

    surface state cannot be obtained because of the cathode geometry and high particles fluxes, measurements of the emitter temperature using a two-color pyrometer were used to determine the oxygen surface coverage and characterize the rate processes that occur during poisoning. A model describing the material transport in the plasma discharge was developed and is used to predict the barium and oxygen fluxes to the emitter surface during cathode operation by solving the species continuity and momentum equations. The dominant ionization process for molecular oxygen in the plasma gas is resonant charge exchange with xenon ions. Barium is effectively recycled in the plasma; however, BaO and O2 are not. The model shows that the oxygen flux to the surface is not diffusion limited. Experimental results indicate that the oxygen poisoning rate is slow and that the oxygen poisoning coverage on the emitter surface is less than 3%. A time-dependent model of the reaction kinetics of oxygen and barium at the tungsten surface was developed using the experimental results. The experiments and kinetics model indicate that the dominant processes at the emitter surface are dissociative adsorption of O2, sputtering of the O2 precursor, and desorption of O. Ion sputtering of the weakly bound O2 precursor state limits the poisoning rate and yields low oxygen coverage. Removal of chemisorbed atomic oxygen is dominated by thermal processes. Based on the low oxygen coverage and long poisoning transients, plasma cathodes appear to be able to withstand higher oxygen concentrations than vacuum cathodes.

  7. Cathode performance improvement in calcium-thionyl chloride cells

    NASA Astrophysics Data System (ADS)

    Walker, C. W., Jr.; Wade, W. L., Jr.; Binder, M.; Gilman, S.

    1986-08-01

    Carbon cathode performance in calcium-thionyl chloride cells was markedly improved with a cathode comprised of a mixture of high and low surface area carbon blacks. Addition of sulfur dioxide gas to the electrolyte further enhanced cathode performance and electrolyte conductivity. Load potentials and cathode life were nearly equal to that of the analogous lithium based system. The advantage of the calcium based system is its potential for greater safety.

  8. Reproducible cold fusion reaction using a complex cathode

    SciTech Connect

    Arata, Y.; Zhang, Y.C. )

    1992-09-01

    This paper discusses a new complex cathode which was developed, consisting of a nickel (or palladium) rod with a palladium layer applied by plasma spraying. High reproducibility of a cold fusion reaction is confirmed by using this cathode. The palladium layer activates the surface functions of the deuterated cathode, and reliable evidence is obtained that a new type of heat generation occurred in the complex cathode.

  9. Protective factors and predictors of vulnerability to chronic stress: a comparative study of 4 communities after 7 years of continuous rocket fire.

    PubMed

    Gelkopf, Marc; Berger, Rony; Bleich, Avraham; Silver, Roxane Cohen

    2012-03-01

    Many communities across the world are chronically exposed to extreme violence. Responses of residents from a city and rural community in Southern Israel, both exposed to 7 years of daily mortar fire, were compared to residents from demographically, socio-economically and geographically comparable non-exposed control samples to examine protective factors and predictors of vulnerability to chronic war-related attacks. Samples from a highly exposed city (Sderot) and a highly exposed rural community region (Otef Aza), along with a demographically comparable comparison non-exposed city (Ofakim) and non-exposed rural community region (Hevel Lachish), were obtained in 2007 using Random Digit Dialing. In total, 740 individuals (81.8% participation rate) were interviewed about trauma exposure, mental health, functioning and health care utilization. In the highly exposed city of Sderot, 97.8% of residents had been in close proximity to falling rockets; in the highly exposed rural community region of Otef Aza, 95.5% were similarly exposed. Despite exposure to chronic rocket attacks, residents of Otef Aza evidenced little symptomatology: only one person (1.5%) reported symptoms consistent with probable posttraumatic stress disorder (PTSD) and functioning levels did not differ from those of non-exposed communities. In contrast, posttraumatic stress (PTS), distress, functional impairment and health care utilization were substantially higher in the highly exposed city of Sderot than the other three communities. Lack of resources was associated with increased vulnerability among city residents; predictors of PTS across all samples included being female, older, directly exposed to rockets, history of trauma, suffering economic loss, and lacking social support. Increased community solidarity, sense of belonging and confidence in authorities may have served a protective function for residents of rural communities, despite the chronic attacks to which they were exposed. Copyright

  10. Combined plasma and thermal hollow cathode insert model

    NASA Technical Reports Server (NTRS)

    Katz, Ira; Polk, James E.; Mikellides, Ionnis G.; Goebel, Dan m.; Hornbeck, Sarah E.

    2005-01-01

    In this paper, we present the first results from a Hollow Cathode Thermal (HCThermal) model that uses the spatially distributed plasma fluxes calculated by the InsertRegion of an Orificed Cathode (IROrCa2D) code as the heat source to predict the hollow cathode and insert temperatures.

  11. Energetic ion production and electrode erosion in hollow cathode discharges

    NASA Technical Reports Server (NTRS)

    Goebel, Dan M.; Jameson, Kristina; Katz, Ira; Mikellides, Ioannis

    2005-01-01

    Ions with energies significantly in excess of the discharge voltage have been reported in high current hollow cathode discharges. Models of DC potential hills downstream of the cathode and ion acoustic instabilities in a double layer postulated in the cathode orifice have been proposed to explain these energetic ions, but have not been substantiated in experiments.

  12. Optical properties of lamps with cold emission cathode

    NASA Astrophysics Data System (ADS)

    Kalenik, Jerzy; Czerwosz, ElŻbieta; Biernacki, Krzysztof; Rymarczyk, Joanna; Stepińska, Izabela

    2016-12-01

    A luminescent lamp was constructed and tested. Phosphor excited by electrons is the source of light. The source of electrons is field emission cathode. The cathode is covered with nickel-carbon layer containing carbon nanotubes that enhance electron emission from the cathode. Results of luminance measurements are presented. Luminance is high enough for lighting application.

  13. Combined plasma and thermal hollow cathode insert model

    NASA Technical Reports Server (NTRS)

    Katz, Ira; Polk, James E.; Mikellides, Ionnis G.; Goebel, Dan m.; Hornbeck, Sarah E.

    2005-01-01

    In this paper, we present the first results from a Hollow Cathode Thermal (HCThermal) model that uses the spatially distributed plasma fluxes calculated by the InsertRegion of an Orificed Cathode (IROrCa2D) code as the heat source to predict the hollow cathode and insert temperatures.

  14. The loss of material from the cathode of metal arcs

    NASA Technical Reports Server (NTRS)

    Seeliger, R.; Wulfhekel, H.

    1985-01-01

    A study was made of the effect of arc length, cathode thickness, current strength, gas pressure and the chemical nature of the cathode material and filling gases upon the material loss from Cu, Fe, and Ag cathodes in arcs. The results show that the analysis of the phenomenon is complex and the energy balance is difficult to formulate.

  15. High-voltage virtual-cathode microwave simulations

    SciTech Connect

    Thode, L.; Snell, C.M.

    1991-01-01

    In contrast to a conventional microwave tube, a virtual-cathode device operates above the space-charge limit where the depth of the space-charge potential is sufficiently large to cause electron reflection. The region associated with electron reflection is referred to as a virtual cathode. Microwaves can be generated through oscillations in the position of the virtual cathode and by reflexing electrons trapped in the potential well formed between the real and virtual cathodes. A virtual-cathode device based on the first mechanism is a vircator while one based on latter mechanism is a reflex diode. A large number of low-voltage virtual-cathode microwave configurations have been investigated. Initial simulations of a high-voltage virtual-cathode device using a self-consistent particle-in-cell code indicated reasonable conversion efficiency with no frequency chirping. The nonchirping character of the high-voltage virtual-cathode device lead to the interesting possibility of locking four very-high-power microwave devices together using the four transmission lines available at Aurora. Subsequently, in support of two high-voltage experiments, simulations were used to investigate the effect of field-emission threshold and velvet position on the cathode; anode and cathode shape; anode-cathode gap spacing; output waveguide radius; diode voltage; a cathode-coaxial-cavity resonator; a high-frequency ac-voltage drive; anode foil scattering and energy loss; and ion emission on the microwave frequency and power. Microwave

  16. Rapid Thermal Annealing of Cathode-Garnet Interface toward High-Temperature Solid State Batteries.

    PubMed

    Liu, Boyang; Fu, Kun; Gong, Yunhui; Yang, Chunpeng; Yao, Yonggang; Wang, Yanbin; Wang, Chengwei; Kuang, Yudi; Pastel, Glenn; Xie, Hua; Wachsman, Eric D; Hu, Liangbing

    2017-08-09

    High-temperature batteries require the battery components to be thermally stable and function properly at high temperatures. Conventional batteries have high-temperature safety issues such as thermal runaway, which are mainly attributed to the properties of liquid organic electrolytes such as low boiling points and high flammability. In this work, we demonstrate a truly all-solid-state high-temperature battery using a thermally stable garnet solid-state electrolyte, a lithium metal anode, and a V2O5 cathode, which can operate well at 100 °C. To address the high interfacial resistance between the solid electrolyte and cathode, a rapid thermal annealing method was developed to melt the cathode and form a continuous contact. The resulting interfacial resistance of the solid electrolyte and V2O5 cathode was significantly decreased from 2.5 × 10(4) to 71 Ω·cm(2) at room temperature and from 170 to 31 Ω·cm(2) at 100 °C. Additionally, the diffusion resistance in the V2O5 cathode significantly decreased as well. The demonstrated high-temperature solid-state full cell has an interfacial resistance of 45 Ω·cm(2) and 97% Coulombic efficiency cycling at 100 °C. This work provides a strategy to develop high-temperature all-solid-state batteries using garnet solid electrolytes and successfully addresses the high contact resistance between the V2O5 cathode and garnet solid electrolyte without compromising battery safety or performance.

  17. Electrochemical struvite precipitation from digestate with a fluidized bed cathode microbial electrolysis cell.

    PubMed

    Cusick, Roland D; Ullery, Mark L; Dempsey, Brian A; Logan, Bruce E

    2014-05-01

    Microbial electrolysis cells (MECs) can be used to simultaneously convert wastewater organics to hydrogen and precipitate struvite, but scale formation at the cathode surface can block catalytic active sites and limit extended operation. To promote bulk phase struvite precipitation and minimize cathode scaling, a two-chamber MEC was designed with a fluidized bed to produce suspended particles and inhibit scale formation on the cathode surface. MEC operation elevated the cathode pH to between 8.3 and 8.7 under continuous flow conditions. Soluble phosphorus removal using digester effluent ranged from 70 to 85% with current generation, compared to 10-20% for the control (open circuit conditions). At low current densities (≤2 mA/m(2)), scouring of the cathode by fluidized particles prevented scale accumulation over a period of 8 days. There was nearly identical removal of soluble phosphorus and magnesium from solution, and an equimolar composition in the collected solids, supporting phosphorus removal by struvite formation. At an applied voltage of 1.0 V, energy consumption from the power supply and pumping (0.2 Wh/L, 7.5 Wh/g-P) was significantly less than that needed by other struvite formation methods based on pH adjustment such as aeration and NaOH addition. In the anode chamber, current generation led to COD oxidation (1.1-2.1 g-COD/L-d) and ammonium removal (7-12 mM) from digestate amended with 1 g/L of sodium acetate. These results indicate that a fluidized bed cathode MEC is a promising method of sustainable electrochemical nutrient and energy recovery method for nutrient rich wastewaters.

  18. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection of... (CRTs) and Processed CRT Glass Undergoing Recycling. Used, broken CRTs are not solid wastes if they meet... destined for recycling and if they meet the following requirements: (1) Storage. The broken CRTs must be...

  19. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection of... (CRTs) and Processed CRT Glass Undergoing Recycling. Used, broken CRTs are not solid wastes if they meet... destined for recycling and if they meet the following requirements: (1) Storage. The broken CRTs must be...

  20. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection of... (CRTs) and Processed CRT Glass Undergoing Recycling. Used, broken CRTs are not solid wastes if they meet... destined for recycling and if they meet the following requirements: (1) Storage. The broken CRTs must be...

  1. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection of... (CRTs) and Processed CRT Glass Undergoing Recycling. Used, broken CRTs are not solid wastes if they meet... destined for recycling and if they meet the following requirements: (1) Storage. The broken CRTs must be...

  2. Influence of potential, chlorides, pH, and precharging time on embrittlement of cathodically polarized prestressing steel

    SciTech Connect

    Hartt, W.H.; Kumria, C.C. ); Kessler, R.J. )

    1993-05-01

    Corrosion of prestressing steel in concrete has become a major technological problem in highways, buildings, and pipeline structures. While cathodic protection is recognized as an appropriate technique to mitigate corrosion of reinforcing steel in concrete, the possibility of environmental cracking (hydrogen embrittlement) in the case of prestressing tendon has limited application to this usage. To establish the appropriateness of cathodic protection for prestressing steel, constant extension rate testing was performed on smooth and notched wire specimens in deaerated Ca(OH)[sub 2] solutions as a function of potential, [Cl-], pH, and precharging time. Results indicated potential is the most important of these variables, and a threshold value of [minus]0.90 V[sub SCE] was identified below which embrittlement is enhanced. Notched specimens, which may best simulate the geometry of corroded tendon, particularly were susceptible when compared to smooth tendon. Failure of some tendons in this condition could occur upon application of cathodic protection, even when potential is positive to [minus]0.90 V[sub SCE]. Other aspects of cathodic protection utility for prestressed concrete are reviewed.

  3. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection of... (CRTs) and Processed CRT Glass Undergoing Recycling. Used, broken CRTs are not solid wastes if they meet... destined for recycling and if they meet the following requirements: (1) Storage. The broken CRTs must...

  4. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a one-time... to export used, intact CRTs for reuse, the notifier's name, address, and EPA ID number (if...

  5. Role of iNOS gene expression in the anti-inflammatory and tissue protective mechanisms of continuous wave at 630-905nm and 905nm superpulsed laser therapy

    NASA Astrophysics Data System (ADS)

    Mandel, Arkady; Moriyama, Yumi; Fong, Jamie; Dumoulin-White, Roger; Lilge, Lothar

    2012-03-01

    Up regulation of iNOS gene expression is playing a role in the initiation of the anti-inflammatory and tissue protective mechanisms related to nitric oxide (NO) for continuous wave red and infrared as well as 905nm superpulsed laser therapy (SPLT). The iNOS expression before and after laser therapy was evaluated in a zymosan-induced acute arthritis model, in knee joints of young (<15 weeks), middle aged (>15 weeks and < 35 weeks) and old (> 35 weeks) FVB/N-Tg (iNOS-luc) mice by bioluminescence imaging.

  6. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    SciTech Connect

    Harlan U. Anderson

    2000-03-31

    . However, they have the potential of being useful as an interface on the anode side of the electrolyte. NexTech has focused much of its effort during the past few months on establishing tape casting methods for porous LSM substrates. This work, performed under a separate DOE-funded program, involved tape casting formulations comprising LSM powders with bi-modal particle size distributions and fugitive pore forming additives. Sintered LSM substrates with porosities in the 30 to 40 vol% range, and pore sizes of 10 {approx} 20 microns have been prepared. In addition, tape casting formulations involving composite mixtures of LSM and Sm-doped ceria (SDC) have been evaluated. The LSM/SDC cathode substrates are expected to provide better performance at low temperatures. Characterization of these materials is currently underway.

  7. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    SciTech Connect

    Harlan U. Anderson; Wayne Huebner; Igor Kosacki

    2001-09-30

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. In this portion of study we have focused on producing YSZ films on porous LSM substrates. When using the polymer precursor there are a number of obstacles to overcome in order to form dense electrolyte layers on porous substrates (cathode or anode). Probably the most difficult problems are: (1) Extreme penetration of the polymer into the substrate must be prevented. (2) Shrinkage cracking must be avoided. (3) Film thickness in the 1 to 5{micro}m range must be achieved. We have demonstrated that cracking due to shrinkage involved during the elimination of solvents and organic matter and densification of the remaining oxide is not a problem as long as the resulting oxide film is < {approx} 0.15 {micro}m in thickness. We have also shown that we can make thicker films by making multiple depositions if the substrate is smooth (roughness {le} 0.1 {micro}m) and contains no surface pores > 0.2 {micro}m. The penetration of the polymer into the porous substrate can be minimized by increasing the viscosity of the polymer and reducing the largest pore at the surface of the substrate to {le} 0.2 {micro}m. We have shown that this can be done, but we have also shown that it is difficult to make dense films that are defect free with areas > 1 cm{sup 2}. This is because of the roughness of the substrate and the difficulty in making a substrate which does not have surface voids > 0.2 {micro}m. Thus the process works well for dense, smooth substrates for films < 1 {micro}m thick, but is difficult to apply to rough, porous surfaces and to make film thickness > 1 {micro}m. As a result of these problems, we have been addressing the issue of how to make dense films in the thickness range of 1 to 5 {micro}m on sintered porous substrates without introducing cracks and holes due to shrinkage and surface voids? These

  8. Composite Cathode for High-Power Density Solid Oxide Fuel Cells

    SciTech Connect

    Ilwon Kim; Scott Barnett; Yi Jiang; Manoj Pillai; Nikkia McDonald; Dan Gostovic; Zhongryang Zhan; Jiang Liu

    2004-01-31

    Reduction of solid oxide fuel cell (SOFC) operating temperature will play a key role in reducing the stack cost by allowing the use of low-cost metallic interconnects and new approaches to sealing, while making applications such as transportation more feasible. Reported results for anode-supported SOFCs show that cathode polarization resistance is the primary barrier to achieving high power densities at operating temperatures of 700 C and lower. This project aims to identify and develop composite cathodes that could reduce SOFC operating temperatures below 700 C. This effort focuses on study and use of (La,Sr)(Co,Fe)O{sub 3} (LSCF) based composite cathodes, which have arguably the best potential to substantially improve on the currently-used, (La,Sr)MnO{sub 3}-Yttria-stabilized Zirconia. During this Phase I, it was successfully demonstrated that high performances can be achieved with LSCF/Gadolinium-Doped Ceria composite cathodes on Ni-based anode supported cells operating at 700 C or lower. We studied electrochemical reactions at LSCF/Yttria-stabilized Zirconia (YSZ) interfaces, and observed chemical reactions between LSCF and YSZ. By using ceria electrolytes or YSZ electrolytes with ceria diffusion barrier layers, the chemical reactions between LSCF and electrolytes were prevented under cathode firing conditions necessary for the optimal adhesion of the cathodes. The protection provided by ceria layer is expected to be adequate for stable long-term cathode performances, but more testing is needed to verify this. Using ceria-based barrier layers, high performance Ni-YSZ anode supported cells have been demonstrated with maximum power densities of 0.8W/cm2 at 700 C and 1.6W/cm{sup 2} at 800 C. Ni-SDC anode supported cells with SDC electrolytes yielded >1W/cm{sup 2} at 600 C. We speculate that the power output of Ni-YSZ anode supported cell at 700 C and lower, was limited by the quality of the Ceria and Ceria YSZ interface. Improvements in the low

  9. Barium depletion in hollow cathode emitters

    NASA Astrophysics Data System (ADS)

    Polk, James E.; Mikellides, Ioannis G.; Capece, Angela M.; Katz, Ira

    2016-01-01

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al2O3 source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  10. Barium depletion in hollow cathode emitters

    SciTech Connect

    Polk, James E. Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2016-01-14

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al{sub 2}O{sub 3} source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  11. Organic cathode for a secondary battery

    SciTech Connect

    Bugga, R.V.; Distefano, S.; Williams, R.M.; Bankston, C.P.

    1990-10-30

    This patent describes a battery system. It comprises: a first body of liquid meal anode comprising a Group I metal; a record body of liquid cathode comprising a combination of Group I metal salt and Group III metal salt molten at the temperature of operation of the battery containing a minor amount of an organic carbonitrile depolarizer containing at least one adjacent ethylenic bond.

  12. Cathode Holder and Transfer Mechanism Design for Warm Cathode in SRF Electron Gun

    DTIC Science & Technology

    2013-03-13

    Figure 8. cathode assembly inserted into stalk mock-up, released from manipulator. The spring preload is maintained with a cam actuated flexure...interfaces. The internal cam and Vespel SP3 bushings are the only sliding parts, which are internal to the assembly, and any particles generated are...captures the bayonet and cam tool when the flexure is in its released position, eliminating the possibility of this occurrence. Figure 9. Cathode assembly

  13. Study of azo dye decolorization and determination of cathode microorganism profile in air-cathode microbial fuel cells.

    PubMed

    Kumru, Mert; Eren, Hilal; Catal, Tunc; Bermek, Hakan; Akarsubaşi, Alper Tunga

    2012-09-01

    Five textile azo dyes, as part of an artificial mixture, were treated in single-chamber air-cathode microbial fuel cells while simultaneously utilizing acetate for electricity production. Remazol Black, Remazol Brilliant Blue, Remazol Turquoise Blue, Reactive Yellow and Reactive Red at concentrations of 40 or 80 mg L(-1) were decolorized to a similar extent, at averages of 78, 95, 53, 93 and 74%, respectively, in 24 hours. During the process of decolorization, electricity generation from acetate oxidation continued. Power densities obtained in the presence of textile dyes ranged from 347 to 521 mW m(-2) at the current density range of 0.071 - 0.086 mA cm(-2). Microbial community analyses of cathode biofilm exhibited dynamic changes in abundant species following dye decolorization. Upon the addition of the first dye, a major change (63%) in microbial diversity was observed; however, subsequent addition of other dyes did not affect the community profile significantly. Actinobacteria, Aquamicrobium, Mesorhizobium, Ochrobactrum, Thauera, Paracoccus, Achromobacter and Chelatacoccus affiliated phylotypes were the major phylotypes detected. Our results demonstrate that microbial fuel cells could be a promising alternative for treatment of textile wastewaters and an active bacterial community can rapidly be established for simultaneous azo dye decolorization and sustainable electricity generation.

  14. Cathodic behaviour of stainless steel in coastal Indian seawater: calcareous deposits overwhelm biofilms.

    PubMed

    Eashwar, M; Subramanian, G; Palanichamy, S; Rajagopal, G; Madhu, S; Kamaraj, P

    2009-01-01

    Type-316 stainless steel (SS) was investigated as the cathode in galvanic couples in full-strength seawater from the Gulf of Mannar on the southeast coast of India. Tests were devised to examine the impact of SS cathodes on anode materials with or without the accrual of marine biofilms. Biofilmed SS cathodes significantly enhanced the rate of corrosion of nickel, causing noble shifts in the couple potentials. With mild steel and zinc as the anodes, calcareous deposits developed quite rapidly on the SS cathodes and led to a significant reduction of bacterial numbers. The calcareous deposits also caused substantial reduction of galvanic corrosion rates for mild steel, whereas there was no difference for zinc. The deposits were identified by XRD as essentially carbonates, oxides and hydroxides of calcium and magnesium. Potentiodynamic polarization performed on the actual couples after disconnection and equilibration provided reasonable interpretations of the galvanic corrosion trends. Data from this work suggest that a potential of about -0.70 V vs. saturated calomel electrode (SCE) should provide optimum protection of SS in warmer, full-strength seawater that supports the precipitation of calcareous deposits. The criterion commonly recommended for temperate conditions of lower water temperature and estuarine waters of lower alkalinity is -1.0 V (SCE).

  15. Cathode depth sensing in CZT detectors

    NASA Astrophysics Data System (ADS)

    Hong, JaeSub; Bellm, Eric C.; Grindlay, Jonathan E.; Narita, Tomohiko

    2004-02-01

    Measuring the depth of interaction in thick Cadmium-Zinc-Telluride (CZT) detectors allows improved imaging and spectroscopy for hard X-ray imaging above 100 keV. The Energetic X-ray Imaging Survey Telescope (EXIST) will employ relatively thick (5 - 10 mm) CZT detectors, which are required to perform the broad energy-band sky survey. Interaction depth information is needed to correct events to the detector "focal plane" for correct imaging and can be used to improve the energy resolution of the detector at high energies by allowing event-based corrections for incomplete charge collection. Background rejection is also improved by allowing low energy events from the rear and sides of the detector to be rejected. We present experimental results of intereaction depth sensing in a 5 mm thick pixellated Au-contact IMARAD CZT detector. The depth sensing was done by making simultaneous measurements of cathode and anode signals, where the interaction depth at a given energy is proportional to the ratio of cathode/anode signals. We demonstrate how a simple empirical formula describing the event distributions in the cathode/anode signal space can dramatically improve the energy resolution. We also estimate the energy and depth resolution of the detector as a function of the energy and the interaction depth. We also show a depth-sensing prototype system currently under development for EXIST in which cathode signals from 8, 16 or 32 crystals can be read-out by a small multi-channel ASIC board that is vertically edge-mounted on the cathode electrode along every second CZT crystal boundary. This allows CZT crystals to be tiled contiguously with minimum impact on throughput of incoming photons. The robust packaging is crucial in EXIST, which will employ very large area imaging CZT detector arrays.

  16. Long lifetime hollow cathodes for 30-cm mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Kerslake, W. R.

    1976-01-01

    An experimental investigation of hollow cathodes for 30-cm Hg bombardment thrusters was carried out. Both main and neutralizer cathode configurations were tested with both rolled foil inserts coated with low work function material and impregnated porous tungsten inserts. Temperature measurements of an impregnated insert at various positions in the cathode were made. These, along with the cathode thermal profile are presented. A theory for rolled foil and impregnated insert operation and lifetime in hollow cathodes is developed. Several endurance tests, as long as 18000 hours at emission currents of up to 12 amps were attained with no degradation in performance.

  17. Development program on a Spindt cold-cathode electron gun

    NASA Technical Reports Server (NTRS)

    Spindt, C. A.

    1982-01-01

    A thin film field emission cathode (TFFEC) array and a cold cathode electron gun based on the emitter were developed. A microwave tube gun that uses the thin film field emission cathode as an electron source is produced. State-of-the-art cathodes were fabricated and tested. The tip-packing density of the arrays were increased thereby increasing the cathode's current density capability. The TFFEC is based on the well known field emission effect and was conceived to exploit the advantages of that phenomenon while minimizing the difficulties associated with conventional field emission structures, e.g. limited life and high voltage requirements. Field emission follows the Fowler-Nordheim equation.

  18. Carbon-containing cathodes for enhanced electron emission

    DOEpatents

    Cao, Renyu; Pan, Lawrence; Vergara, German; Fox, Ciaran

    2000-01-01

    A cathode has electropositive atoms directly bonded to a carbon-containing substrate. Preferably, the substrate comprises diamond or diamond-like (sp.sup.3) carbon, and the electropositive atoms are Cs. The cathode displays superior efficiency and durability. In one embodiment, the cathode has a negative electron affinity (NEA). The cathode can be used for field emission, thermionic emission, or photoemission. Upon exposure to air or oxygen, the cathode performance can be restored by annealing or other methods. Applications include detectors, electron multipliers, sensors, imaging systems, and displays, particularly flat panel displays.

  19. Electrochemical Wear of Carbon Cathodes in Electrowinning of Aluminum

    NASA Astrophysics Data System (ADS)

    Tschöpe, Kati; Støre, Anne; Solheim, Asbjørn; Skybakmoen, Egil; Grande, Tor; Ratvik, Arne Petter

    2013-11-01

    Cathode wear is the main factor limiting the lifetime of high-amperage aluminum electrolysis cells with graphitized cathodes. The current article deals with an investigation of cathode wear in a laboratory cell, where the cathode is directly exposed to the electrolyte during electrolysis. The wear was shown to be electrochemical in nature and dependent on the current density, the rotation speed, and the depth of prefabricated slots in the cylindrical cathodes. The wear mechanism is discussed with respect to kinetics influencing the electrochemistry as well as the solubility of aluminum carbide in the electrolyte.

  20. Progress of air-breathing cathode in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Zejie; Mahadevan, Gurumurthy Dummi; Wu, Yicheng; Zhao, Feng

    2017-07-01

    Microbial fuel cell (MFC) is an emerging technology to produce green energy and vanquish the effects of environmental contaminants. Cathodic reactions are vital for high electrical power density generated from MFCs. Recently tremendous attentions were paid towards developing high performance air-breathing cathodes. A typical air-breathing cathode comprises of electrode substrate, catalyst layer, and air-diffusion layer. Prior researches demonstrated that each component influenced the performance of air-breathing cathode MFCs. This review summarized the progress in development of the individual component and elaborated main factors to the performance of air-breathing cathode.

  1. Cathode scraper system and method of using the same for removing uranium

    SciTech Connect

    Williamson, Mark A; Wiedmeyer, Stanley G; Willit, James L; Barnes, Laurel A; Blaskovitz, Robert J

    2015-02-03

    Embodiments include a cathode scraper system and/or method of using the same for removing uranium. The cathode scraper system includes a plurality of cathode assemblies. Each cathode assembly includes a plurality of cathode rods. The cathode scraper system also includes a cathode scraper assembly configured to remove purified uranium deposited on the plurality of cathode rods. The cathode scraper assembly includes a plurality of scrapers arranged in a lattice, and each scraper of the plurality of scrapers is arranged to correspond to a different cathode rod.

  2. Emission current control system for multiple hollow cathode devices

    NASA Technical Reports Server (NTRS)

    Beattie, John R. (Inventor); Hancock, Donald J. (Inventor)

    1988-01-01

    An emission current control system for balancing the individual emission currents from an array of hollow cathodes has current sensors for determining the current drawn by each cathode from a power supply. Each current sensor has an output signal which has a magnitude proportional to the current. The current sensor output signals are averaged, the average value so obtained being applied to a respective controller for controlling the flow of an ion source material through each cathode. Also applied to each controller are the respective sensor output signals for each cathode and a common reference signal. The flow of source material through each hollow cathode is thereby made proportional to the current drawn by that cathode, the average current drawn by all of the cathodes, and the reference signal. Thus, the emission current of each cathode is controlled such that each is made substantially equal to the emission current of each of the other cathodes. When utilized as a component of a multiple hollow cathode ion propulsion motor, the emission current control system of the invention provides for balancing the thrust of the motor about the thrust axis and also for preventing premature failure of a hollow cathode source due to operation above a maximum rated emission current.

  3. Polymer coatings as separator layers for microbial fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Watson, Valerie J.; Saito, Tomonori; Hickner, Michael A.; Logan, Bruce E.

    2011-03-01

    Membrane separators reduce oxygen flux from the cathode into the anolyte in microbial fuel cells (MFCs), but water accumulation and pH gradients between the separator and cathode reduces performance. Air cathodes were spray-coated (water-facing side) with anion exchange, cation exchange, and neutral polymer coatings of different thicknesses to incorporate the separator into the cathode. The anion exchange polymer coating resulted in greater power density (1167 ± 135 mW m-2) than a cation exchange coating (439 ± 2 mW m-2). This power output was similar to that produced by a Nafion-coated cathode (1114 ± 174 mW m-2), and slightly lower than the uncoated cathode (1384 ± 82 mW m-2). Thicker coatings reduced oxygen diffusion into the electrolyte and increased coulombic efficiency (CE = 56-64%) relative to an uncoated cathode (29 ± 8%), but decreased power production (255-574 mW m-2). Electrochemical characterization of the cathodes ex situ to the MFC showed that the cathodes with the lowest charge transfer resistance and the highest oxygen reduction activity produced the most power in MFC tests. The results on hydrophilic cathode separator layers revealed a trade off between power and CE. Cathodes coated with a thin coating of anion exchange polymer show promise for controlling oxygen transfer while minimally affecting power production.

  4. Scenario for Hollow Cathode End-Of-Life

    NASA Technical Reports Server (NTRS)

    Sarver-Verhey, Timothy R.

    2000-01-01

    Recent successful hollow cathode life tests have demonstrated that lifetimes can meet the requirements of several space applications. However, there are no methods for assessing cathode lifetime short of demonstrating the requirement. Previous attempts to estimate or predict cathode lifetime were based on relatively simple chemical depletion models derived from the dispenser cathode community. To address this lack of predicative capability, a scenario for hollow cathode lifetime under steady-state operating conditions is proposed. This scenario has been derived primarily from the operating behavior and post-test condition of a hollow cathode that was operated for 28,000 hours. In this scenario, the insert chemistry evolves through three relatively distinct phases over the course of the cathode lifetime. These phases are believed to correspond to demonstrable changes in cathode operation. The implications for cathode lifetime limits resulting from this scenario are examined, including methods to assess cathode lifetime without operating to End-of- Life and methods to extend the cathode lifetime.

  5. Icodextrin-based continuous ambulatory peritoneal dialysis therapy effectively reduces left ventricular mass index and protects cardiac function in patients with end-stage renal disease.

    PubMed

    Oba, Ikuko; Shinozaki, Michiya; Harada, Kenji; Mori, Takefumi; Kanai, Hidetoshi

    2013-01-01

    Increased left ventricular mass index (LVMI) is commonly observed in patients undergoing peritoneal dialysis (PD). The present study aimed to determine the effect of icodextrin (Ico) on LVMI in PD patients with maintained residual renal function (RRF). This retrospective study included 18 patients (12 men, 6 women; average age: 62 +/- 10 years) diagnosed with indications for PD therapy and divided into two groups: those treated with Ico (Ico group) and without Ico (non-Ico group). Echocardiography was performed at the beginning of continuous ambulatory PD and after 6 and 12 months. A significant reduction in LVMI (p < 0.01) and an increase in ultrafiltration (p < 0.01) were observed after 6 months of lco treatment and were maintained for 12 months. Ejection fraction was significantly lower in the non-Ico group after 12 months (p < 0.01), but was not altered in the Ico group. Blood pressure, cardiothoracic ratio, urine volume, and N-terminal prohormone of brain natriuretic peptide were unaffected by PD treatment up to 12 months. The year-averaged ultrafiltration and the reduction in LVMI were significantly correlated (p < 0.05). Ico effectively improved LVMI and maintained ejection fraction in end-stage renal disease patients within 1 year from PD initiation. Notably, treatment with Ico resulted in a reduction of LVMI (associated with increased ultrafiltration), with no significant reduction in RRF.

  6. Predicting criteria continuous concentrations of metals or metalloids for protecting marine life by use of quantitative ion characteristic-activity relationships-species sensitivity distributions (QICAR-SSD).

    PubMed

    Qie, Yu; Chen, Cheng; Guo, Fei; Mu, Yunsong; Sun, Fuhong; Wang, Hao; Wang, Ying; Wang, Huanhua; Wu, Fengchang; Hu, Qing; Dang, Zhi; Giesy, John P

    2017-02-26

    Marine pollution by metals has been a major challenge for ecological systems; however, water quality criteria (WQC) for metals in saltwater is still lacking. Especially from a regulatory perspective, chronic effects of metals on marine organisms should receive more attention. A quantitative ion characteristic-activity relationships-species sensitivity distributions (QICAR-SSD) model, based on chronic toxicities for eight marine organisms, was established to predict the criteria continuous concentrations (CCCs) of 21 metals. The results showed that the chronic toxicities of various metals had good relationships with their physicochemical properties. Predicted CCCs of six metals (Hg(2+), Cu(2+), Pb(2+), Cd(2+), Ni(2+) and Zn(2+)) were in accordance with the values recommended by the U.S. EPA, with prediction errors being less than an order of magnitude. The QICAR-SSD approach provides an alternative tool to empirical methods and can be useful for deriving scientifically defensible WQC for metals for marine organisms and conducting ecological risk assessments.

  7. Virtual cathode microwave generator having annular anode slit

    DOEpatents

    Kwan, Thomas J. T.; Snell, Charles M.

    1988-01-01

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.

  8. Cathode R&D for Future Light Sources

    SciTech Connect

    Dowell, D.H.; Bazarov, I.; Dunham, B.; Harkay, K.; Hernandez-Garcia; Legg, R.; Padmore, H.; Rao, T.; Smedley, J.; Wan, W.; /LBL, Berkeley

    2010-05-26

    This paper reviews the requirements and current status of cathodes for accelerator applications, and proposes a research and development plan for advancing cathode technology. Accelerator cathodes need to have long operational lifetimes and produce electron beams with a very low emittance. The two principal emission processes to be considered are thermionic and photoemission with the photocathodes being further subdivided into metal and semi-conductors. Field emission cathodes are not included in this analysis. The thermal emittance is derived and the formulas used to compare the various cathode materials. To date, there is no cathode which provides all the requirements needed for the proposed future light sources. Therefore a three part research plan is described to develop cathodes for these future light source applications.

  9. Cathode R&D for future light sources.

    SciTech Connect

    Dowell, D. H.; Bazarov, I.; Dunham, B.; Harkay, K.; Hernandez-Garcia, C.; Legg, R.; Padmore, H.; Rao, T.; Smedley, J.; Wan, W.; Accelerator Systems Division; SLAC National Accelerator Lab.; Cornell Univ.; Thomas Jefferson Lab.; Univ. of Wisconsin; LBNL; BNL

    2010-03-18

    This paper reviews the requirements and current status of cathodes for accelerator applications, and proposes a research and development plan for advancing cathode technology. Accelerator cathodes need to have long operational lifetimes and produce electron beams with a very low emittance. The two principal emission processes to be considered are thermionic and photoemission with the photocathodes being further subdivided into metal and semi-conductors. Field emission cathodes are not included in this analysis. The thermal emittance is derived and the formulas used to compare the various cathode materials. To date, there is no cathode which provides all the requirements needed for the proposed future light sources. Therefore a three part research plan is described to develop cathodes for these future light source applications.

  10. Cathodic properties of different stainless steels in natural seawater

    SciTech Connect

    Johnsen, R.; Bardal, E.

    1985-05-01

    The cathodic properties of a number of stainless steels, which were exposed to natural seawater flowing at 0 to 2.5 m/s and polarized to potentials from -300 to -950 mV SCE, have been studied. The current density development at constant potential and the free corrosion potential during the exposure time were recorded continuously. At the end of the exposure period, after approximately 28 to 36 days of exposure, polarization curves were determined. After one to three weeks of exposure, depending on the water velocity, microbiological activity on the surface caused an increase in the current density requirement of the specimen. An explanation for the mechanism behind the current density increase caused by slime production from marine bacteria may be increased exchange current density, i/sub 0/. There was no measurable calcareous deposit on the stainless steel surfaces at the end of the exposure periods.

  11. Nanostructured material for advanced energy storage : magnesium battery cathode development.

    SciTech Connect

    Sigmund, Wolfgang M.; Woan, Karran V.; Bell, Nelson Simmons

    2010-11-01

    Magnesium batteries are alternatives to the use of lithium ion and nickel metal hydride secondary batteries due to magnesium's abundance, safety of operation, and lower toxicity of disposal. The divalency of the magnesium ion and its chemistry poses some difficulties for its general and industrial use. This work developed a continuous and fibrous nanoscale network of the cathode material through the use of electrospinning with the goal of enhancing performance and reactivity of the battery. The system was characterized and preliminary tests were performed on the constructed battery cells. We were successful in building and testing a series of electrochemical systems that demonstrated good cyclability maintaining 60-70% of discharge capacity after more than 50 charge-discharge cycles.

  12. 40 CFR 40.165 - Continuation grants.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Continuation grants. 40.165 Section 40.165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE RESEARCH AND DEMONSTRATION GRANTS § 40.165 Continuation grants. To be eligible for a continuation grant...

  13. 40 CFR 40.165 - Continuation grants.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Continuation grants. 40.165 Section 40.165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE RESEARCH AND DEMONSTRATION GRANTS § 40.165 Continuation grants. To be eligible for a continuation grant...

  14. 40 CFR 1065.150 - Continuous sampling.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Continuous sampling. 1065.150 Section 1065.150 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.150 Continuous sampling. You may use...

  15. 40 CFR 1065.150 - Continuous sampling.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Continuous sampling. 1065.150 Section 1065.150 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.150 Continuous sampling. You may use...

  16. 40 CFR 1065.150 - Continuous sampling.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Continuous sampling. 1065.150 Section 1065.150 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.150 Continuous sampling. You may use...

  17. 40 CFR 1065.150 - Continuous sampling.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Continuous sampling. 1065.150 Section 1065.150 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.150 Continuous sampling. You may use...

  18. 40 CFR 1065.150 - Continuous sampling.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Continuous sampling. 1065.150 Section 1065.150 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.150 Continuous sampling. You may use...

  19. 40 CFR 40.165 - Continuation grants.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 1 2012-07-01 2012-07-01 false Continuation grants. 40.165 Section 40.165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE RESEARCH AND DEMONSTRATION GRANTS § 40.165 Continuation grants. To be eligible for a continuation...

  20. 40 CFR 40.165 - Continuation grants.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Continuation grants. 40.165 Section 40.165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE RESEARCH AND DEMONSTRATION GRANTS § 40.165 Continuation grants. To be eligible for a continuation...

  1. 40 CFR 40.165 - Continuation grants.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Continuation grants. 40.165 Section 40.165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE RESEARCH AND DEMONSTRATION GRANTS § 40.165 Continuation grants. To be eligible for a continuation...

  2. Appropriate exposure estimates for wildlife risk assessments of crop protection products based on continuous radio telemetry: A case study with woodpigeons.

    PubMed

    Ludwigs, Jan-Dieter; Ebeling, Markus; Fredricks, Timothy B; Murfitt, Roger C; Kragten, Steven

    2017-05-01

    The registration of pesticides follows guidance published by the European Food Safety Authority (EFSA). As a default, the EFSA guidance document on risk assessment for birds and mammals assumes that animals feed exclusively on pesticide-treated fields. However, the guidance document suggests refining the risk via the proportion of food animals obtain from a treated field or specific crop (expressed via the portion of diet obtained from a treated area [PT value]). The EFSA guidance equalizes the portion of food taken from a treated area per day with the portion of time spent potentially foraging over the course of a day within this area. Therefore, radiotracking is commonly used to gather species-, crop-, and season-specific PT data, and radio telemetry of continuously tracked farmland species can deliver individual PT values for a given day, crop, and species. In the present study the authors introduce a way of calculating long-term PT values based on empirically recorded data via telemetry field studies for the most appropriate use in wildlife risk assessment of pesticides. The novel aspect of the proposal is that the authors follow the prerequisite given by EFSA to cover the long-term risk by introducing 21-d PT values that aim to cover both intra- and inter-individual variability of foraging focal farmland species in cropped habitats. Currently, the intra-individual variability is not taken into account for PT calculations. The authors demonstrate this approach and discuss EFSA guidance input requirements for PT values recorded in field studies, based on a PT field study conducted with woodpigeons (Columba palumbus) radiotracked in an agricultural landscape in the United Kingdom. The results indicate that a 21-d PT value considering intra-individual variability gives a more appropriate PT value for long-term risk assessments. Environ Toxicol Chem 2017;36:1270-1277. © 2016 SETAC. © 2016 SETAC.

  3. The effect of cathode geometry on barium transport in hollow cathode plasmas

    SciTech Connect

    Polk, James E. Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2014-05-14

    The effect of barium transport on the operation of dispenser hollow cathodes was investigated in numerical modeling of a cathode with two different orifice sizes. Despite large differences in cathode emitter temperature, emitted electron current density, internal xenon neutral and plasma densities, and size of the plasma-surface interaction region, the barium transport in the two geometries is qualitatively very similar. Barium is produced in the insert and flows to the surface through the porous structure. A buildup of neutral Ba pressure in the plasma over the emitter surface can suppress the reactions supplying the Ba, restricting the net production rate. Neutral Ba flows into the dense Xe plasma and has a high probability of being ionized at the periphery of this zone. The steady state neutral Ba density distribution is determined by a balance between pressure gradient forces and the drag force associated with collisions between neutral Ba and neutral Xe atoms. A small fraction of the neutral Ba is lost upstream. The majority of the neutral Ba is ionized in the high temperature Xe plasma and is pushed back to the emitter surface by the electric field. The steady state Ba{sup +} ion density distribution results from a balance between electrostatic and pressure forces, neutral Xe drag and Xe{sup +} ion drag with the dominant forces dependent on location in the discharge. These results indicate that hollow cathodes are very effective at recycling Ba within the discharge and therefore maintain a high coverage of Ba on the emitter surface, which reduces the work function and sustains high electron emission current densities at moderate temperatures. Barium recycling is more effective in the cathode with the smaller orifice because the Ba is ionized in the dense Xe plasma concentrated just upstream of the orifice and pushed back into the hollow cathode. Despite a lower emitter temperature, the large orifice cathode has a higher Ba loss rate through the orifice

  4. MODELING THE CATHODIC REGION IN CREVICE CORROSION UNDER A THIN ELECTROLYTE FILM INCLUDING PARTICULATES

    SciTech Connect

    A.S. Agarwal; U. Landau; X. Shan; J.H. Payer

    2006-03-14

    Crevice corrosion may be limited by the capacity of the external cathodic region to support anodic dissolution currents within the crevice. The analysis here focuses on behavior of metal surfaces covered by a thin ({approx}microns) layer of the electrolyte film including particulates. The particulates can affect the cathode current capacity (I{sub total}) by increasing the solution resistance (''volume effect'') and by decreasing the electrode area (''surface effect''). In addition, there can be particulate effects on oxygen reduction kinetics and oxygen transport. This work simulates and characterizes the effect of a uniform particulate monolayer on the cathode current capacity for steady state conditions in the presence of a thin electrolyte film. Particulate configurations with varying particle size, shape, arrangement, volume fraction, and electrode area coverage were numerically modeled as a function of the properties of the system. It is observed that the effects of particles can be fully accounted for in terms of two corrections: the volume blockage effect on the electrolyte resistivity can be correlated using Bruggeman's equation, and the electrode coverage effect can be modeled in terms of a simple area correction to the kinetics expression. For the range of parameters analyzed, applying these two correction factors, cathodes covered with thin electrolyte films that contain particles can be represented in terms of equivalent homogeneous electrolytes that can then be analyzed using simpler approaches. Continuing work will examine the effects of greater volume fractions of particles and multiple particle layers.

  5. 40 CFR 52.1831 - Visibility protection.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 4 2012-07-01 2012-07-01 false Visibility protection. 52.1831 Section 52.1831 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) North Dakota § 52.1831 Visibility protection...

  6. 40 CFR 52.1831 - Visibility protection.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Visibility protection. 52.1831 Section 52.1831 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) North Dakota § 52.1831 Visibility protection...

  7. 40 CFR 52.1831 - Visibility protection.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Visibility protection. 52.1831 Section 52.1831 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) North Dakota § 52.1831 Visibility protection...

  8. 40 CFR 52.1831 - Visibility protection.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Visibility protection. 52.1831 Section 52.1831 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) North Dakota § 52.1831 Visibility protection...

  9. 40 CFR 52.1831 - Visibility protection.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 4 2011-07-01 2011-07-01 false Visibility protection. 52.1831 Section 52.1831 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) North Dakota § 52.1831 Visibility protection...

  10. Effect of primer composition on cathodic disbonding resistance and adhesion durability of three layer polyethylene coated steel pipe

    SciTech Connect

    Tsuri, S.; Takao, K.; Mochizuki, K.

    1998-12-31

    The cathodic disbonding resistance and adhesion durability of three layer polyethylene coated steel pipe were studied from the viewpoint of water permeability and the water uptake of dicyandiamide-imidazole cured epoxy primer. The reaction between the epoxy resin and dicyandiamide generates hydroxyl groups. Therefore, as the content of dicyandiamide increased, the water uptake of the primer increased and the water diffusion rate of the primer decreased because of the strong interaction between hydroxyl reaction product and water molecules. Excellent cathodic disbonding resistance and adhesion durability were observed when the primer had the lowest water permeability which was expressed as the product of the water uptake and water diffusion rate. On the other hand, the addition of a corrosion protective pigment to the primer improved cathodic disbonding resistance and adhesion durability when the primer had high water uptake, which secured the sufficient solubility of the pigment. Polyethylene coated steel pipes are often used as pipelines for oil and natural gas.

  11. NUMERICAL MODELING OF CATHODE CONTACT MATERIAL DENSIFICATION

    SciTech Connect

    Koeppel, Brian J.; Liu, Wenning N.; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2011-11-01

    Numerical modeling was used to simulate the constrained sintering process of the cathode contact layer during assembly of solid oxide fuel cells (SOFCs). A finite element model based on the continuum theory for sintering of porous bodies was developed and used to investigate candidate low-temperature cathode contact materials. Constitutive parameters for various contact materials under investigation were estimated from dilatometry screening tests, and the influence of processing time, processing temperature, initial grain size, and applied compressive stress on the free sintering response was predicted for selected candidate materials. The densification behavior and generated stresses within a 5-cell planar SOFC stack during sintering, high temperature operation, and room temperature shutdown were predicted. Insufficient constrained densification was observed in the stack at the proposed heat treatment, but beneficial effects of reduced grain size, compressive stack preload, and reduced thermal expansion coefficient on the contact layer densification and stresses were observed.

  12. Magnetron cathodes in plasma electrode Pockels cells

    DOEpatents

    Rhodes, M.A.

    1995-04-25

    Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal. 5 figs.

  13. Magnetron cathodes in plasma electrode pockels cells

    DOEpatents

    Rhodes, Mark A.

    1995-01-01

    Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating. pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal.

  14. Development of a high-performance composite cathode for LT-SOFC

    NASA Astrophysics Data System (ADS)

    Lee, Byung Wook

    -ionized (DI) water, zeta potential profile of ESB powder in DI water as a function of pH was first achieved. The effect of a dispersant (ammonium citrate dibasic) on the stability of ESB powder dispersed in DI water was also investigated. Knowledge of BRO7 wet chemical synthesis from previous study was utilized for final product of in-situ BRO7-ESB composite cathodes. Such prepared composite particles were characterized and the electrochemical performance of in-situ BRO7-ESB composite cathodes was examined as well. Performance enhancement was observed so that ASR values of 0.097Ocm2 and 3.58Ocm2 were achieved at 700°C and 500°C, respectively, which were 19% and 22% improvement, respectively compared to those of conventionally mixed composite cathodes of BRO7-ESB. Finally, a highly controlled nanostructured BRO7-ESB composite cathode was developed by infiltration of BRO7 onto ESB scaffolds to maximize the effective TPB length, to improve the connectivity of ESB phase inside the cathode for better oxygen-ion diffusion, and to minimize delamination between the electrolyte and cathode layers. ESB scaffolds were first established by adding a graphite pore-former and controlling heat treatment condition. Nano-sized BRO7 particles were successfully created on the surface of previously formed ESB scaffold by infiltration of concentrated (Bi, Ru) nitrate solution followed by the optimized heat treatment. Such prepared composite cathodes exhibited superior electrochemical performance to conventionally made BRO7-ESB composite cathodes and even better than GNC BRO7-SS ESB developed in this dissertation, e.g. 0.073Ocm2 at 700°C and 1.82Ocm2 at 500°C, respectively. This cathode system was revealed to be highly competitive among all the reported composite cathodes consisting of the same or different materials prepared by various processing techniques. It was demonstrated that the extended TPB length from continuous network of BRO7 nanoparticles and better connectivity of ESB scaffolds

  15. Sub-2 nm Thick Fluoroalkylsilane Self-Assembled Monolayer-Coated High Voltage Spinel Crystals as Promising Cathode Materials for Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Zettsu, Nobuyuki; Kida, Satoru; Uchida, Shuhei; Teshima, Katsuya

    2016-08-01

    We demonstrate herein that an ultra-thin fluoroalkylsilane self-assembled monolayer coating can be used as a modifying agent at LiNi0.5Mn1.5O4‑δcathode/electrolyte interfaces in 5V-class lithium-ion batteries. Bare LiNi0.5Mn1.5O4‑δ cathode showed substantial capacity fading, with capacity dropping to 79% of the original capacity after 100 cycles at a rate of 1C, which was entirely due to dissolution of Mn3+ from the spinel lattice via oxidative decomposition of the organic electrolyte. Capacity retention was improved to 97% on coating ultra-thin FAS17-SAM onto the LiNi0.5Mn1.5O4 cathode surface. Such surface protection with highly ordered fluoroalkyl chains insulated the cathode from direct contact with the organic electrolyte and led to increased tolerance to HF.

  16. The hollow cathode effect in a radio-frequency driven microhollow cathode discharge in nitrogen

    NASA Astrophysics Data System (ADS)

    Zhang, Lianzhu; Zhao, Guoming; Wang, Jing; Han, Qing

    2016-02-01

    A two-dimensional particle-in-cell Monte-Carlo code has been developed to study the physical mechanism of the hollow cathode effect (HCE) in an rf microhollow cathode discharge (rf-MHCD). Under the simulated conditions, the HCE in the rf-MHCD is the result of sheath-superposition, and both α ionization and γ ionization play a role. However, α ionization mode is predominant. Electrons undergo a pendular motion during the negative portion of the rf cycle. When the rf hollow electrode has a positive voltage, the majority of the electrons move toward the rf electrode, and the mean electron energy near the rf electrode is higher than that in a dc hollow cathode discharge, resulting in a large number of energetic electrons bombarding the hollow cathode wall, an important characteristic of the rf-MHCD. When the hollow cathode aperture is sufficiently small, many electrons strike the hollow electrode and are removed from the discharge space, so that the plasma density decreases. The average energy of the ions in the quasi-neutral plasma region near the axis is greater than the thermal energy in a molecular gas. Therefore, high density, high energy, and high chemical activity are characteristic advantages of rf-MHCD plasma sources.

  17. Copper chloride cathode for a secondary battery

    NASA Technical Reports Server (NTRS)

    Bugga, Ratnakumar V. (Inventor); Distefano, Salvador (Inventor); Nagasubramanian, Ganesan (Inventor); Bankston, Clyde P. (Inventor)

    1990-01-01

    Higher energy and power densities are achieved in a secondary battery based on molten sodium and a solid, ceramic separator such as a beta alumina and a molten catholyte such as sodium tetrachloroaluminate and a copper chloride cathode. The higher cell voltage of copper chloride provides higher energy densities and the higher power density results from increased conductivity resulting from formation of copper as discharge proceeds.

  18. A model of hollow cathode plasma chemistry

    NASA Technical Reports Server (NTRS)

    Katz, I.; Anderson, J. R.; Polk, J. E.; Brophy, J. R.

    2002-01-01

    We have developed a new model of hollow cathode plasma chemistry based on the observation that xenon ion mobility is diffusion limited due to resonant charge exchange reactions. The model shows that vapor phase barium atoms are ionized almost immediately and electric fields accelerate the ions upstream from the emission zone. We have also applied the model to the orifice region, where the resultant ion generation profile correlates with previously reported orifice erosion.

  19. Barium Depletion in Hollow Cathode Emitters

    NASA Technical Reports Server (NTRS)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  20. Copper chloride cathode for a secondary battery

    NASA Astrophysics Data System (ADS)

    Bugga, Ratnakumar V.; Distefano, Salvador; Nagasubramanian, Ganesan; Bankston, Clyde P.

    1990-07-01

    Higher energy and power densities are achieved in a secondary battery based on molten sodium and a solid, ceramic separator such as a beta alumina and a molten catholyte such as sodium tetrachloroaluminate and a copper chloride cathode. The higher cell voltage of copper chloride provides higher energy densities and the higher power density results from increased conductivity resulting from formation of copper as discharge proceeds.