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Sample records for alkali corrosion resistance

  1. Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure and method of processing

    DOEpatents

    Brown, Jr., Jesse J.; Hirschfeld, Deidre A.; Li, Tingkai

    1993-12-07

    Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure are created using sol-gel processes. The processes have particular application in creating calcium magnesium zirconium phosphate, CMZP, coatings and foams.

  2. Corrosion resistance of stainless steels during thermal cycling in alkali nitrate molten salts.

    SciTech Connect

    Bradshaw, Robert W.; Goods, Steven Howard

    2001-09-01

    The corrosion behavior of three austenitic stainless steels was evaluated during thermal cycling in molten salt mixtures consisting of NaNO{sub 3} and KNO{sub 3}. Corrosion tests were conducted with Types 316, 316L and 304 stainless steels for more than 4000 hours and 500 thermal cycles at a maximum temperature of 565 C. Corrosion rates were determined by chemically descaling coupons. Metal losses ranged from 5 to 16 microns and thermal cycling resulted in moderately higher corrosion rates compared to isothermal conditions. Type 316 SS was somewhat more corrosion resistant than Type 304 SS in these tests. The effect of carbon content on corrosion resistance was small, as 316L SS corroded only slightly slower than 316 SS. The corrosion rates increased as the dissolved chloride content of the molten salt mixtures increased. Chloride concentrations approximating 1 wt.%, coupled with thermal cycling, resulted in linear weight loss kinetics, rather than parabolic kinetics, which described corrosion rates for all other conditions. Optical microscopy and electron microprobe analysis revealed that the corrosion products consisted of iron-chromium spinel, magnetite, and sodium ferrite, organized as separate layers. Microanalysis of the elemental composition of the corrosion products further demonstrated that the chromium content of the iron-chromium spinel layer was relatively high for conditions in which parabolic kinetics were observed. However, linear kinetics were observed when the spinel layer contained relatively little chromium.

  3. Corrosion-resistant coating development

    SciTech Connect

    Stinton, D.P.; Kupp, D.M.; Martin, R.L.

    1997-12-01

    SiC-based heat exchangers have been identified as the prime candidate material for use as heat exchangers in advanced combined cycle power plants. Unfortunately, hot corrosion of the SiC-based materials created by alkali metal salts present in the combustion gases dictates the need for corrosion-resistant coatings. The well-documented corrosion resistance of CS-50 combined with its low (and tailorable) coefficient of thermal expansion and low modulus makes CS-50 an ideal candidate for this application. Coatings produced by gelcasting and traditional particulate processing have been evaluated.

  4. Method for inhibiting alkali metal corrosion of nickel-containing alloys

    DOEpatents

    DeVan, Jackson H.; Selle, James E.

    1983-01-01

    Structural components of nickel-containing alloys within molten alkali metal systems are protected against corrosion during the course of service by dissolving therein sufficient aluminum, silicon, or manganese to cause the formation and maintenance of a corrosion-resistant intermetallic reaction layer created by the interaction of the molten metal, selected metal, and alloy.

  5. Electrical Resistivity of Alkali Elements.

    DTIC Science & Technology

    1976-01-01

    rubidium, cesium, and francium ) and contains recommended reference values (or provisional or typical values). The compiled data include all the...and information on the electrical resistivity of alkali elements (lithium, sodium, potassium, rubidium, cesium, and francium ) and contains...107Ic. Magnetic Flux Density Dependence o.. .. ... .... 112 4.6. Francium ..........................115j a. Temperature Dependence

  6. Stress corrosion resistant fasteners

    NASA Technical Reports Server (NTRS)

    Roach, T. A.

    1985-01-01

    A family of high performance aerospace fasteners made from corrosion resistant alloys for use in applications where corrosion and stress-corrosion cracking are of major concern are discussed. The materials discussed are mainly A-286, Inconel 718, MP35N and MP159. Most of the fasteners utilize cold worked and aged materials to achieve the desired properties. The fasteners are unique in that they provide a combination of high strength and immunity to stress corrosion cracking not previously attainable. A discussion of fastener stress corrosion failures is presented including a review of the history and a description of the mechanism. Case histories are presented to illustrate the problems which can arise when material selection is made without proper regard for the environmental conditions. Mechanical properties and chemical compositions are included for the fasteners discussed. Several aspects of the application of high performance corrosion resistant fasteners are discussed including galvanic compatibility and torque-tension relationships.

  7. Corrosion-resistant uranium

    DOEpatents

    Hovis, Jr., Victor M.; Pullen, William C.; Kollie, Thomas G.; Bell, Richard T.

    1983-01-01

    The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

  8. Corrosion-resistant uranium

    DOEpatents

    Hovis, V.M. Jr.; Pullen, W.C.; Kollie, T.G.; Bell, R.T.

    1981-10-21

    The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

  9. Corrosion-resistant metal surfaces

    DOEpatents

    Sugama, Toshifumi

    2009-03-24

    The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

  10. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, T.D.

    1996-07-23

    Ceramic materials are disclosed which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200--550 C or organic salt (including SO{sub 2} and SO{sub 2}Cl{sub 2}) at temperatures of 25--200 C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components. 1 fig.

  11. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, Thomas D.

    1996-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  12. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, Thomas D.

    1995-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  13. Corrosion resistant PEM fuel cell

    DOEpatents

    Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K.; Cunningham, Kevin M.

    2011-06-07

    A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

  14. Corrosion resistant PEM fuel cell

    DOEpatents

    Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K.; Cunningham, Kevin M.

    2002-01-01

    A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

  15. Corrosive resistant heat exchanger

    DOEpatents

    Richlen, Scott L.

    1989-01-01

    A corrosive and errosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is conveyed through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium.

  16. High temperature alkali corrosion of ceramics in coal gas: Final report

    SciTech Connect

    Pickrell, G.R.; Sun, T.; Brown, J.J. Jr.

    1994-12-31

    There are several ceramic materials which are currently being considered for use as structural elements in coal combustion and coal conversion systems because of their thermal and mechanical properties. These include alumina (refractories, membranes, heat engines); silicon carbide and silicon nitride (turbine engines, internal combustion engines, heat exchangers, particulate filters); zirconia (internal combustion engines, turbine engines, refractories); and mullite and cordierite (particulate filters, refractories, heat exchangers). High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. The objective of this research is to systematically evaluate the alkali corrosion resistance of the most commonly used structural ceramics including silicon carbide, silicon nitride, cordierite, mullite, alumina, aluminum titanate, and zirconia. The study consists of identification of the alkali reaction products and determination of the kinetics of the alkali reactions as a function of temperature and time. 145 refs., 29 figs., 12 tabs.

  17. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  18. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  19. Burner rig alkali salt corrosion of several high temperature alloys

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.; Lowell, C. E.

    1977-01-01

    The hot corrosion of five alloys was studied in cyclic tests in a Mach 0.3 burner rig into whose combustion chamber various aqueous salt solutions were injected. Three nickel-based alloys, a cobalt-base alloy, and an iron-base alloy were studied at temperatures of 700, 800, 900, and 1000 C with various salt concentrations and compositions. The relative resistance of the alloys to hot corrosion attack was found to vary with temperature and both concentration and composition of the injected salt solution. Results indicate that the corrosion of these alloys is a function of both the presence of salt condensed as a liquid on the surface and of the composition of the gas phases present.

  20. Burner rig alkali salt corrosion of several high temperature alloys

    NASA Technical Reports Server (NTRS)

    Deadmore, D.; Lowell, C.

    1977-01-01

    The hot corrosion of five alloys was studied in cyclic tests in a Mach 0.3 burner rig into whose combustion chamber various aqueous salt solutions were injected. Three nickel-base alloys (IN-792, IN-738, and IN-100), a cobalt-base alloy (MM-509), and an iron-base alloy (304 stainless steel) were studied at temperatures of 700, 800, 900, and 1000 C with various salt concentrations and compositions. The relative resistance of the alloys to hot corrosion attack was found to vary with temperature and with both the concentration and composition of the injected salt solution. Results indicate that the corrosion of these alloys is a function of both the presence of salt condensed as a liquid on the surface and of the composition of the gas phases present.

  1. Corrosion-resistant sulfur concretes

    NASA Astrophysics Data System (ADS)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1983-04-01

    Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements. Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

  2. Lithium and Sodium Resistance of Alkali Metal Vapor Resistant Glasses

    NASA Astrophysics Data System (ADS)

    Kishinevski, Anatoly; Hall, Matthew

    2014-05-01

    A common challenge in atomic physics is that of containing an alkali metal vapor at an elevated temperature and concurrently being able to excite and probe atomic transitions within. Typically glass is used as the material to construct the container, as it is easy to manipulate into any geometry and offers thermal, mechanical, and optical properties that no other material is capable. Unfortunately it has been well established that alkali metal gasses/vapors react readily with silica containing glass and results in a progressive darkening of the material. As the darkening reaction progresses, the optical transmission properties of the glass progressively degrade to an eventual point of uselessness. Alkali metals have been used extensively in frequency standards and magnetometers. The finite life of these alkali metal vapor-containing devices has been accepted despite varying attempts by different teams to solve this problem. As a viable solution, it has been identified there exist a family of glass compositions that contain a marginal amount of silica, may be lampworked using traditional glassblowing techniques, and that offer substantially better alkali vapor resistance. The evaluation of these glasses and their resistance to sodium and lithium vapor at varying pressures and temperatures are discussed.

  3. Surface modification for corrosion resistance

    SciTech Connect

    Natesan, K.

    1993-06-01

    The raw gas environments that arise from coal gasification have chemical compositions that are low in pO{sub 2} and moderate-to-high in pS{sub 2}. Metallic materials for service in such an environment undergo predominantly sulfidation attack at temperatures of 400 to 700{degree}C. Modification of alloy compositions in bulk can alter the scaling processes and lead to improvements in corrosion resistance, but the benefits can only be attained at temperatures much higher than the service temperatures of the components. Modification of surfaces of structural components by several of the coating techniques examined in this study showed substantial benefit in corrosion resistance when tested in simulated coal gasification environments. The paper presents several examples of surface modification and their corrosion performance.

  4. Corrosion resistant coating

    DOEpatents

    Wrobleski, Debra A.; Benicewicz, Brian C.; Thompson, Karen G.; Bryan, Coleman J.

    1997-01-01

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  5. Corrosion resistant coating

    DOEpatents

    Wrobleski, D.A.; Benicewicz, B.C.; Thompson, K.G.; Bryan, C.J.

    1997-08-19

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  6. Coal Ash Corrosion Resistant Materials Testing

    SciTech Connect

    D. K. McDonald; P. L. Daniel; D. J. DeVault

    2003-08-31

    In April 1999, three identical superheater test sections were installed into the Niles Unit No.1 for the purpose of testing and ranking the coal ash corrosion resistance of candidate superheater alloys. The Niles boiler burns high sulfur coal (3% to 3.5%) that has a reasonably high alkali content, thus the constituents necessary for coal ash corrosion are present in the ash. The test sections were controlled to operate with an average surface metal temperature from approximately 1060 F to 1210 F which was well within the temperature range over which coal ash corrosion occurs. Thus, this combination of aggressive environment and high temperature was appropriate for testing the performance of candidate corrosion-resistant tube materials. Analyses of the deposit and scale confirmed that the aggressive alkali-iron-trisulfate constituent was present at the metal surface and active in tube metal wastage. The test sections were constructed so that the response of twelve different candidate tube and/or coating materials could be studied. The plan was to remove and evaluate one of the three test sections at time intervals of 1 year, 3 years, and 5 years. This would permit an assessment of performance of the candidate materials as a function of time. This report provides the results of the evaluation of Test Section C, including the samples that remained in the Test Section for the full exposure period as well as those that were removed early. The analysis of Test Section C followed much the same protocol that was employed in the assessment of Test Section A. Again, the focus was on determining and documenting the relative corrosion rates of the candidate materials. The detailed results of the investigation are included in this report as a series of twelve appendices. Each appendix is devoted to the performance of one of the candidate alloys. The table below summarizes metal loss rate for the worst case sample of each of the candidate materials for both Test Sections A and C

  7. CORROSION RESISTANT JACKETED METAL BODY

    DOEpatents

    Brugmann, E.W.

    1958-08-26

    Reactor faul elements of the elongated cylindrical type which are jacketed in a corrosion resistant material are described. Each feel element is comprised of a plurality of jacketed cylinders of fissionable material in end to end abutting relationship, the jackets being welded together at their adjoining ends to retain the individual segments together and seat the interior of the jackets.

  8. Corrosion resistant metallic bipolar plate

    DOEpatents

    Brady, Michael P.; Schneibel, Joachim H.; Pint, Bruce A.; Maziasz, Philip J.

    2007-05-01

    A corrosion resistant, electrically conductive component such as a bipolar plate for a PEM fuel cell includes 20 55% Cr, balance base metal such as Ni, Fe, or Co, the component having thereon a substantially external, continuous layer of chromium nitride.

  9. CORROSION RESISTANT JACKETED METAL BODY

    DOEpatents

    Brugmann, E.W.

    1958-08-26

    Jacketed metal bodies of the type used as fuel elements for nuclear reactors, which contain an internal elongated body of fissionable material jacketed in a corrosion resistant metal are described. The ends of the internal bodies are provided with screw threads having a tapered outer end. The jacket material overlaps the ends and extends into the tapered section of the screw threaded opening. Screw caps with a mating tapered section are screwed into the ends of the body to compress the jacket material in the tapered sections to provtde an effective seal against corrosive gases and liquids.

  10. Coatings for improved corrosion resistance

    SciTech Connect

    Natesan, K.

    1992-05-01

    Several coating approaches are being developed to resist attack in coal-fired environments and thereby minimize corrosion of underlying substrate alloys and extend the time for onset of breakaway corrosion. In general, coating systems can be classified as either diffusion or overlay type, which are distinguished principally by the method of deposition and the structure of the resultant coating-substrate bond. The coating techniques examined are pack cementation, electrospark deposition, physical and chemical vapor deposition, plasma spray, and ion implantation. In addition, ceramic coatings are used in some applications.

  11. Subtask 6.6 - SiAION Coatings for Alkali-Resistant Silicon Nitride. Topical report

    SciTech Connect

    1997-02-25

    The efficiency of a gas turbine can be improved by increasing operating temperature. Construction materials should both meet high strength requirements and exhibit hot alkali corrosion resistance. Structural ceramics based on silicon nitride are promising candidates for high temperature engineering applications because of their high strength and good resistance to corrosion. Their performance varies significantly with the mechanical properties of boundary phases which, in turn, depend on their chemical composition, thickness of the amorphous phase, and the deformation process. To make silicon nitride ceramics tough, SiAlON ceramics were developed with controlled crystallization of the amorphous grain boundary phase. Crystallization of the grain boundary glass improves the high temperature mechanical properties of silicon nitride ceramics. Thus, the knowledge of silicon oxynitride ceramics corrosion behavior in Na{sub 2}SO{sub 4} becomes important for engineers in designing appropriate part for turbines working at high temperatures. So far there has been no report concerning alkali attack on SiAlON ceramics in the presence of SO{sub 2} and chlorine in flue gas. The goal of this project was to investigate alkali corrosion of SiAlON-Y structural ceramics under combustion conditions in the presence of sodium derived components.

  12. High temperature alkali corrosion in high velocity gases

    NASA Technical Reports Server (NTRS)

    Lowell, C. E.; Sidik, S. M.; Deadmore, D. L.

    1981-01-01

    The effects of potential impurities in coal derived liquids such as Na, K, Mg, Ca and Cl on the accelerated corrosion of IN-100, U-700, IN-792 and Mar-M509 were investigated using a Mach 0.3 burner rig for times to 1000 hours in one hour cycles. These impurities were injected in combination as aqueous solutions into the combustor of the burner rig. The experimental matrix utilized was designed statistically. The extent of corrosion was determined by metal recession. The metal recession data were fitted by linear regression to a polynomial expression which allows both interpolation and extrapolation of the data. As anticipated, corrosion increased rapidly with Na and K, and a marked maximum in the temperature response was noted for many conditions. In contrast, corrosion decreased somewhat as the Ca, Mg and Cl contents increased. Extensive corrosion was observed at concentrations of Na and K as low as 0.1 PPM at long times.

  13. Alkali resistant optical coatings for alkali lasers and methods of production thereof

    DOEpatents

    Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

    2014-11-18

    In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

  14. CORROSION RESISTANT JACKETED METAL BODY

    DOEpatents

    Brugmann, E.W.

    1958-08-26

    S>Metal jacketed metallic bodies of the type used as feel elements fer nuclear reactors are presented. The fuel element is comprised of a plurality of jacketed cylindrical bodies joined in end to end abutting relationship. The abutting ends of the internal fissionable bodies are provided with a mating screw and thread means for joining the two together. The jacket material is of a corrosion resistant metal and overlaps the abutting ends of the internal bodies, thereby effectively sealing these bodies from contact with exteral reactive gases and liquids.

  15. A corrosive resistant heat exchanger

    DOEpatents

    Richlen, S.L.

    1987-08-10

    A corrosive and erosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is pumped through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium. 3 figs., 3 tabs.

  16. Coal Ash Corrosion Resistant Materials Testing

    SciTech Connect

    D. K. McDonald; P. L. Daniel; D. J. DeVault

    2007-12-31

    In April 1999, three identical superheater test sections were installed into the Niles Unit No.1 for the purpose of testing and ranking the coal ash corrosion resistance of candidate superheater alloys. The Niles boiler burns high sulfur coal (3% to 3.5%) that has a moderate alkali content (0.2% sodium equivalents), thus the constituents necessary for coal ash corrosion are present in the ash. The test sections were controlled to operate with an average surface metal temperature from approximately 1060 F to 1210 F which was within the temperature range over which coal ash corrosion occurs. Thus, this combination of aggressive environment and high temperature was appropriate for testing the performance of candidate corrosion-resistant tube materials. Analyses of the deposit and scale confirmed that aggressive alkali sulfate constituents were present at the metal surface and active in tube metal wastage. The test sections were constructed so that the response of twelve different candidate tube and/or coating materials could be studied. The plan was to remove and evaluate one of the three test sections at time intervals of 1 year, 3 years, and 5 years. This would permit an assessment of performance of the candidate materials as a function of time. Test Section A was removed in November 2001 after about 24 months of service at the desired steam temperature set point, with about 15.5 months of exposure at full temperature. A progress report, issued in October 2002, was written to document the performance of the candidate alloys in that test section. The evaluation described the condition of each tube sample after exposure. It involved a determination of the rate of wall thickness loss for these samples. In cases where there was more than one sample of a candidate material in the test section, an assessment was made of the performance of the alloy as a function of temperature. Test Sections B and C were examined during the November 2001 outage, and it was decided that

  17. Corrosion resistant storage container for radioactive material

    DOEpatents

    Schweitzer, Donald G.; Davis, Mary S.

    1990-01-01

    A corrosion resistant long-term storage container for isolating radioactive waste material in a repository. The container is formed of a plurality of sealed corrosion resistant canisters of different relative sizes, with the smaller canisters housed within the larger canisters, and with spacer means disposed between judxtaposed pairs of canisters to maintain a predetermined spacing between each of the canisters. The combination of the plural surfaces of the canisters and the associated spacer means is effective to make the container capable of resisting corrosion, and thereby of preventing waste material from leaking from the innermost canister into the ambient atmosphere.

  18. Corrosion resistant storage container for radioactive material

    DOEpatents

    Schweitzer, D.G.; Davis, M.S.

    1984-08-30

    A corrosion resistant long-term storage container for isolating high-level radioactive waste material in a repository is claimed. The container is formed of a plurality of sealed corrosion resistant canisters of different relative sizes, with the smaller canisters housed within the larger canisters, and with spacer means disposed between juxtaposed pairs of canisters to maintain a predetermined spacing between each of the canisters. The combination of the plural surfaces of the canisters and the associated spacer means is effective to make the container capable of resisting corrosion, and thereby of preventing waste material from leaking from the innermost canister into the ambient atmosphere.

  19. Corrosion resistant positive electrode for high-temperature, secondary electrochemical cell

    DOEpatents

    Otto, Neil C.; Warner, Barry T.; Smaga, John A.; Battles, James E.

    1983-01-01

    The corrosion rate of low carbon steel within a positive electrode of a high-temperature, secondary electrochemical cell that includes FeS as active material is substantially reduced by incorporating therein finely divided iron powder in stoichiometric excess to the amount required to form FeS in the fully charged electrode. The cell typically includes an alkali metal or alkaline earth metal as negative electrode active material and a molten metal halide salt as electrolyte. The excess iron permits use of inexpensive carbon steel alloys that are substantially free of the costly corrosion resistant elements chromium, nickel and molybdenum while avoiding shorten cell life resulting from high corrosion rates.

  20. Corrosion resistant positive electrode for high-temperature, secondary electrochemical cell

    DOEpatents

    Otto, N.C.; Warner, B.T.; Smaga, J.A.; Battles, J.E.

    1982-07-07

    The corrosion rate of low carbon steel within a positive electrode of a high-temperature, secondary electrochemical cell that includes FeS as active material is substantially reduced by incorporating therein finely divided iron powder in stoichiometric excess to the amount required to form FeS in the fully charged electrode. The cell typically includes an alkali metal or alkaline earth metal as negative electrode active material and a molten metal halide salt as electrolyte. The excess iron permits use of inexpensive carbon steel alloys that are substantially free of the costly corrosion resistant elements chromium, nickel and molybdenum while avoiding shorten cell life resulting from high corrosion rates.

  1. Coated Aluminized Film Resists Corrosion

    NASA Technical Reports Server (NTRS)

    Rockoff, H. J.

    1982-01-01

    Commercially available corrosion-protection coating allows less costly metals - aluminum in particular used in heat-reflecting films for thermal barriers. Previously, such films had to incorporate gold as reflective layer to withstand humidity, moisture, and salt spray without corroding. This protective coating prevents corrosion of metalized films during evironmental exposure yet remains flexible, thermally stable and clear.

  2. 46 CFR 111.01-11 - Corrosion-resistant parts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Corrosion-resistant parts. 111.01-11 Section 111.01-11...-GENERAL REQUIREMENTS General § 111.01-11 Corrosion-resistant parts. Each enclosure and part of electric equipment that can be damaged by corrosion must be made of corrosion-resistant materials or of...

  3. 46 CFR 111.01-11 - Corrosion-resistant parts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Corrosion-resistant parts. 111.01-11 Section 111.01-11...-GENERAL REQUIREMENTS General § 111.01-11 Corrosion-resistant parts. Each enclosure and part of electric equipment that can be damaged by corrosion must be made of corrosion-resistant materials or of...

  4. 46 CFR 111.01-11 - Corrosion-resistant parts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Corrosion-resistant parts. 111.01-11 Section 111.01-11...-GENERAL REQUIREMENTS General § 111.01-11 Corrosion-resistant parts. Each enclosure and part of electric equipment that can be damaged by corrosion must be made of corrosion-resistant materials or of...

  5. 46 CFR 111.01-11 - Corrosion-resistant parts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Corrosion-resistant parts. 111.01-11 Section 111.01-11...-GENERAL REQUIREMENTS General § 111.01-11 Corrosion-resistant parts. Each enclosure and part of electric equipment that can be damaged by corrosion must be made of corrosion-resistant materials or of...

  6. Spill-Resistant Alkali-Metal-Vapor Dispenser

    NASA Technical Reports Server (NTRS)

    Klipstein, William

    2005-01-01

    A spill-resistant vessel has been developed for dispensing an alkali-metal vapor. Vapors of alkali metals (most commonly, cesium or rubidium, both of which melt at temperatures slightly above room temperature) are needed for atomic frequency standards, experiments in spectroscopy, and experiments in laser cooling. Although the present spill-resistant alkali-metal dispenser was originally intended for use in the low-gravity environment of outer space, it can also be used in normal Earth gravitation: indeed, its utility as a vapor source was confirmed by use of cesium in a ground apparatus. The vessel is made of copper. It consists of an assembly of cylinders and flanges, shown in the figure. The uppermost cylinder is a fill tube. Initially, the vessel is evacuated, the alkali metal charge is distilled into the bottom of the vessel, and then the fill tube is pinched closed to form a vacuum seal. The innermost cylinder serves as the outlet for the vapor, yet prevents spilling by protruding above the surface of the alkali metal, no matter which way or how far the vessel is tilted. In the event (unlikely in normal Earth gravitation) that any drops of molten alkali metal have been shaken loose by vibration and are floating freely, a mesh cap on top of the inner cylinder prevents the drops from drifting out with the vapor. Liquid containment of the equivalent of 1.2 grams of cesium was confirmed for all orientations with rubbing alcohol in one of the prototypes later used with cesium.

  7. The effect of vacuum annealing on corrosion resistance of titanium

    SciTech Connect

    Chikanov, V.N.; Peshkov, V.V.; Kireev, L.S.

    1994-09-01

    The effect of annealing on the corrosion resistance of OT4-1 sheet titanium in 25% HCl under various air pressures and self-evacuating conditions has been investigated. From the kinetic corrosion curves it follows that the least corrosion resistance of titanium is observed after vacuum annealing. Even low residual air pressure in a chamber improves corrosion resistance. The corrosion resistance of titanium decreases with vacuum-annealing time.

  8. Carbon Surface Modification for Enhanced Corrosion Resistance

    DTIC Science & Technology

    2008-01-01

    LTCSS-treated 316L SS, representing a sig- nificant increase in surface hardness over the substrate material (Vickers 300 HV). To give some perspective...behavior of particular interest to the Navy. Comparison of crevice corrosion resistance for untreated 316L SS and LTCSS- treated 316L is presented in...Fig. 2. Crevice corrosion damage on an untreated 316L coupon following one week of crevice exposure is shown in the center of the figure. LTCSS

  9. Assesment of Alkali Resistance of Basalt Used as Concrete Aggregates

    NASA Astrophysics Data System (ADS)

    al-Swaidani, Aref M.; Baddoura, Mohammad K.; Aliyan, Samira D.; Choeb, Walid

    2015-11-01

    The objective of this paper is to report a part of an ongoing research on the influence of using crushed basalt as aggregates on one of durability-related properties of concrete (i.e. alkali-silica reaction which is the most common form of Alkali-Aggregate Reaction). Alkali resistance has been assessed through several methods specified in the American Standards. Results of petrographic examination, chemical test (ASTM C289) and accelerated mortar bar test (ASTM C1260) have particularly been reported. In addition, the weight change and compressive strength of 28 days cured concrete containing basaltic aggregates were also reported after 90 days of exposure to 10% NaOH solution. Dolomite aggregate were used in the latter test for comparison. The experimental results revealed that basaltic rocks quarried from As-Swaida'a region were suitable for production of aggregates for concrete. According to the test results, the studied basalt aggregates can be classified as innocuous with regard to alkali-silica reaction. Further, the 10% sodium hydroxide attack did not affect the compressive strength of concrete.

  10. Classification of alkali-silica reaction and corrosion distress using acoustic emission

    NASA Astrophysics Data System (ADS)

    Abdelrahman, Marwa; ElBatanouny, Mohamed; Serrato, Michael; Dixon, Kenneth; Larosche, Carl; Ziehl, Paul

    2016-02-01

    The Nuclear Regulatory Commission regulates approximately 100 commercial nuclear power reactor facilities that contribute about 20% of the total electric energy produced in the United States. Half of these reactor facilities are over 30 years old and are approaching their original design service life. Due to economic and durability considerations, significant portions of many of the facilities were constructed with reinforced concrete, including the containment facilities, cooling towers, and foundations. While most of these concrete facilities have performed exceptionally well throughout their initial expected service life, some are beginning to exhibit different forms of concrete deterioration. In this study, acoustic emission (AE) is used to monitor two main concrete deterioration mechanisms; alkali-silica reaction (ASR) distress and corrosion of reinforcing steel. An accelerated ASR test was conducted where specimens were continuously monitored with AE. The results show that AE can detect and classify damage due to ASR distress in the specimens. AE was also used to remotely monitor active corrosion regions in a reactor facility. AE monitoring of accelerated corrosion testing was also conducted on a concrete block specimen cut from a similar reactor building. Electrochemical measurements were conducted to correlate AE activity to quantifiable corrosion measurements and to enhance capabilities for service life prediction.

  11. Corrosion resistant PEM fuel cell

    DOEpatents

    Li, Yang; Meng, Wen-Jin; Swathirajan, Swathy; Harris, Stephen J.; Doll, Gary L.

    1997-01-01

    The present invention contemplates a PEM fuel cell having electrical contact elements (including bipolar plates/septums) comprising a titanium nitride coated light weight metal (e.g., Al or Ti) core, having a passivating, protective metal layer intermediate the core and the titanium nitride. The protective layer forms a barrier to further oxidation/corrosion when exposed to the fuel cell's operating environment. Stainless steels rich in CR, Ni, and Mo are particularly effective protective interlayers.

  12. Corrosion resistant PEM fuel cell

    DOEpatents

    Li, Y.; Meng, W.J.; Swathirajan, S.; Harris, S.J.; Doll, G.L.

    1997-04-29

    The present invention contemplates a PEM fuel cell having electrical contact elements (including bipolar plates/septums) comprising a titanium nitride coated light weight metal (e.g., Al or Ti) core, having a passivating, protective metal layer intermediate the core and the titanium nitride. The protective layer forms a barrier to further oxidation/corrosion when exposed to the fuel cell`s operating environment. Stainless steels rich in Cr, Ni, and Mo are particularly effective protective interlayers. 6 figs.

  13. Corrosion resistant PEM fuel cell

    DOEpatents

    Li, Yang; Meng, Wen-Jin; Swathirajan, Swathy; Harris, Stephen Joel; Doll, Gary Lynn

    2001-07-17

    The present invention contemplates a PEM fuel cell having electrical contact elements (including bipolar plates/septums) comprising a titanium nitride coated light weight metal (e.g., Al or Ti) core, having a passivating, protective metal layer intermediate the core and the titanium nitride. The protective layer forms a barrier to further oxidation/corrosion when exposed to the fuel cell's operating environment. Stainless steels rich in CR, Ni, and Mo are particularly effective protective interlayers.

  14. Corrosion resistant PEM fuel cell

    DOEpatents

    Li, Yang; Meng, Wen-Jin; Swathirajan, Swathy; Harris, Stephen Joel; Doll, Gary Lynn

    2002-01-01

    The present invention contemplates a PEM fuel cell having electrical contact elements (including bipolar plates/septums) comprising a titanium nitride coated light weight metal (e.g., Al or Ti) core, having a passivating, protective metal layer intermediate the core and the titanium nitride. The protective layer forms a barrier to further oxidation/corrosion when exposed to the fuel cell's operating environment. Stainless steels rich in CR, Ni, and Mo are particularly effective protective interlayers.

  15. Oxidation corrosion resistant superalloys and coatings

    NASA Technical Reports Server (NTRS)

    Jackson, Melvin R. (Inventor); Rairden, III, John R. (Inventor)

    1978-01-01

    An article of manufacture having improved high temperature oxidation and corrosion resistance comprising: (a) a superalloy substrate containing a carbide reinforcing phase, and (b) a coating consisting of chromium, aluminum, carbon, at least one element selected from iron, cobalt or nickel, and optionally an element selected from yttrium or the rare earth elements.

  16. Oxidation corrosion resistant superalloys and coatings

    NASA Technical Reports Server (NTRS)

    Jackson, Melvin R. (Inventor); Rairden, III, John R. (Inventor)

    1980-01-01

    An article of manufacture having improved high temperature oxidation and corrosion resistance comprising: (a) a superalloy substrate containing a carbide reinforcing phase, and (b) a coating consisting of chromium, aluminum, carbon, at least one element selected from iron, cobalt or nickel, and optionally an element selected from yttrium or the rare earth elements.

  17. Method of preparing corrosion resistant composite materials

    DOEpatents

    Kaun, Thomas D.

    1993-01-01

    Method of manufacture of ceramic materials which require stability in severely-corrosive environment having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These surfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  18. Alkali-silica reaction resistant concrete using pumice blended cement

    NASA Astrophysics Data System (ADS)

    Ramasamy, Uma

    Durability of structures is a major challenge for the building industry. One of the many types of concrete deterioration that can affect durability is alkali-silica reaction (ASR). ASR has been found in most types of concrete structures, including dams, bridges, pavements, and other structures that are 20 to 50 years old. The degradation mechanism of ASR produces a gel that significantly expands in the presence of water as supplied from the surrounding environment. This expansion gel product can create high stresses and cracking of the concrete, which can lead to other forms of degradation and expensive structural replacement costs. The four essential factors that produce an expansive ASR gel in concrete are the presence of alkalis, siliceous aggregate, moisture, and free calcium hydroxide (CH). If concrete is starved of any one of these essential components, the expansion can be prevented. Reducing CH through the use of a supplementary cementitious material (SCM) such as natural pozzolan pumice is the focus of this research. By using a pozzolan, the amount of CH is reduced with time based on the effectiveness of the pozzolan. Many pozzolans exist, but one such naturally occurring pozzolanic material is pumice. This research focuses on determining the effect of a finely ground pumice as a SCM in terms of its resistance to ASR expansion, as well as improving resistance to other potential concrete durability mechanisms. In spite of having high alkali contents in the pumice, mixtures containing the SCM pumice more effectively mitigated the ASR expansion reaction than other degradation mechanisms. Depending on the reactivity of the aggregates and fineness of the pumice, 10-15% replacement of cement with the pumice was found to reduce the ASR expansion to the acceptable limits. The amount of CH remaining in the concrete was compared to the ASR expansion in order to improve understanding of the role of CH in the ASR reaction. Thermo-gravimetric analysis (TGA) and X

  19. Corrosion-resistant ceramic thermal barrier coating

    NASA Technical Reports Server (NTRS)

    Hodge, P. E.; Levine, S. R.; Miller, R. A.

    1980-01-01

    Two-layer thermal barrier coating, consisting of metal-CrA1Y bond coating and calcium silicate ceramic outer layer, greatly improves resistance of turbine parts to hot corrosion from fuel and air impurities. Both layers can be plasma sprayed, and ceramic layer may be polished to reduce frictional losses. Ceramic provides thermal barrier, so parts operate cooler metal temperatures, coolant flow can be reduced, or gas temperatures increased. Lower grade fuels also can be used.

  20. DIMENSIONALLY STABLE, CORROSION RESISTANT NUCLEAR FUEL

    DOEpatents

    Kittel, J.H.

    1963-10-31

    A method of making a uranium alloy of improved corrosion resistance and dimensional stability is described. The alloy contains from 0-9 weight per cent of an additive of zirconium and niobium in the proportions by weight of 5 to 1 1/ 2. The alloy is cold rolled, heated to two different temperatures, air-cooled, heated to a third temperature, and quenched in water. (AEC)

  1. Pitting corrosion resistant austenite stainless steel

    DOEpatents

    van Rooyen, D.; Bandy, R.

    A pitting corrosion resistant austenite stainless steel comprises 17 to 28 wt. % chromium, 15 to 26 wt. % nickel, 5 to 8 wt. % molybdenum, and 0.3 to 0.5 wt. % nitrogen, the balance being iron, unavoidable impurities, minor additions made in the normal course of melting and casting alloys of this type, and may optionally include up to 10 wt. % of manganese, up to 5 wt. % of silicon, and up to 0.08 wt. % of carbon.

  2. High Gloss Corrosion-Resistant Coatings

    DTIC Science & Technology

    1991-08-27

    34) 5,043,373 1 2 binder derived from the reaction of at least one polyes- HIGH GLOSS CORROSION-RESISTANT ter polyol and a diisocyanate in combination with a...comprises a polyurethane, and more particulary an aliphatic polyurethane derived from the reaction of a saturated polyester polyol and a multi...a molar ratio of acid to pentaerythritol of cyanates include the biurets of the formula: about 1:1 to 2.5:1

  3. Corrosion-Resistant Roof with Integrated Photovoltaic Power System

    DTIC Science & Technology

    2014-02-01

    system as attached to a metal-panel roof that is protected with a high-performance, corrosion -resistant coating . 1.3 Approach A severely corroded...fluoride (PVF) and polyvinylidene fluoride (PVDF) can pro- vide excellent corrosion protection in corrosive environments such as KMC. Sustainable...systems on the corrosion resistance of coated metal roofing systems is not known. Potential corro- sion mechanisms include moisture trapped between the

  4. Evaluation of alkali metal sulfate dew point measurement for detection of hot corrosion conditions in PFBC flue gas

    SciTech Connect

    Helt, J.E.

    1980-11-01

    Hot corrosion in combustion systems is, in general, the accelerated oxidation of nickel, cobalt, and iron-base alloys which occurs in the presence of small amounts of impurities - notably, sodium, sulfur, chlorine, and vanadium. There is no real consensus on which mechanisms are primarily responsible for high-temperature corrosion. One point generally accepted, however, is that corrosion reactions take place at an appreciable rate only in the presence of a liquid phase. When coal is the fuel for combustion, hot corrosion may occur in the form of accelerated sulfidation. It is generally agreed by investigators that molten alkali metal sulfates (Na/sub 2/SO/sub 4/ and K/sub 2/SO/sub 4/) are the principal agents responsible for the occurrence of sulfidation. Although molten sodium sulfate by itself appears to have little or no effect on the corrosion of metal alloys, its presence may increase the accessibility of the bare metal surface to the external atmosphere. If this atmosphere contains either a reductant and/or an oxide such as SiO/sub 2/, SO/sub 3/, or NaOH(Na/sub 2/O), corrosion is likely to occur. Alkali metal sulfate dew point measurement was evaluated as a means of anticipating hot corrosion in the gas turbine of a pressurized fluidized-bed combustion system. The hot corrosion mechanism and deposition rate theory were reviewed. Two methods of dew point measurement, electrical conductivity and remote optical techniques, were identified as having a potential for this application. Both techniques are outlined; practical measurement systems are suggested; and potential problem areas are identified.

  5. Corrosion resistance of monolayer hexagonal boron nitride on copper

    NASA Astrophysics Data System (ADS)

    Mahvash, F.; Eissa, S.; Bordjiba, T.; Tavares, A. C.; Szkopek, T.; Siaj, M.

    2017-02-01

    Hexagonal boron nitride (hBN) is a layered material with high thermal and chemical stability ideal for ultrathin corrosion resistant coatings. Here, we report the corrosion resistance of Cu with hBN grown by chemical vapor deposition (CVD). Cyclic voltammetry measurements reveal that hBN layers inhibit Cu corrosion and oxygen reduction. We find that CVD grown hBN reduces the Cu corrosion rate by one order of magnitude compared to bare Cu, suggesting that this ultrathin layer can be employed as an atomically thin corrosion-inhibition coating.

  6. Corrosion resistance of monolayer hexagonal boron nitride on copper.

    PubMed

    Mahvash, F; Eissa, S; Bordjiba, T; Tavares, A C; Szkopek, T; Siaj, M

    2017-02-13

    Hexagonal boron nitride (hBN) is a layered material with high thermal and chemical stability ideal for ultrathin corrosion resistant coatings. Here, we report the corrosion resistance of Cu with hBN grown by chemical vapor deposition (CVD). Cyclic voltammetry measurements reveal that hBN layers inhibit Cu corrosion and oxygen reduction. We find that CVD grown hBN reduces the Cu corrosion rate by one order of magnitude compared to bare Cu, suggesting that this ultrathin layer can be employed as an atomically thin corrosion-inhibition coating.

  7. Corrosion resistance of monolayer hexagonal boron nitride on copper

    PubMed Central

    Mahvash, F.; Eissa, S.; Bordjiba, T.; Tavares, A. C.; Szkopek, T.; Siaj, M.

    2017-01-01

    Hexagonal boron nitride (hBN) is a layered material with high thermal and chemical stability ideal for ultrathin corrosion resistant coatings. Here, we report the corrosion resistance of Cu with hBN grown by chemical vapor deposition (CVD). Cyclic voltammetry measurements reveal that hBN layers inhibit Cu corrosion and oxygen reduction. We find that CVD grown hBN reduces the Cu corrosion rate by one order of magnitude compared to bare Cu, suggesting that this ultrathin layer can be employed as an atomically thin corrosion-inhibition coating. PMID:28191822

  8. Erosion / Corrosion Resistant Coatings for Compressor Airfoils

    DTIC Science & Technology

    2012-08-29

    2012 2. REPORT TYPE 3 . DATES COVERED 00-00-2012 to 00-00-2012 4. TITLE AND SUBTITLE Erosion / Corrosion Resistant Coatings for Compressor...driver • DoD consumes ≈ $13B in aviation fuel annually • Eroded engines emit 10 to 25% greater pollutants 2 3 Erosive media GAS TURBINE ENGINE...AGT1500 for M1A Tank RTM322 for Merlin Arriel for LUH Gnome for Sea King CF34 for E170     5 T64 for H-53  HPW3000 CFM56 for

  9. Corrosion resistant process piping changes in economics

    SciTech Connect

    Lain, E.H. Jr.

    1996-07-01

    In recent years, the process piping industry has seen dramatic changes occur in corrosion resistant materials. Some changes have occurred in the form of new and modified materials becoming available. However, the most dramatic changes have occurred in the pricing of some older and well known materials. These economic changes have been dramatic and quick, so much so that the old established budget pricing ``rules of thumb`` used for many years to estimate piping projects are no longer valid. In many instances, the prices of some premium metals (titanium, for example) are now on a comparatively equal basis even with high alloys when all factors including densities, special fabrication requirements and service life are taken into account. The purpose of this paper is to discuss some commonly encountered corrosion resistant piping materials, a brief summary of their chemical and mechanical properties and usage. However, the focus of the paper presented will be economic. It will detail the current raw material prices for high alloys including duplex stainless steels, nickel and nickel alloys, Hastelloys+, as well as the reactive metals, zirconium and titanium. In addition, a typical fabricated piping spool in various diameters will be estimated for all of the above metals and the results plotted in graphical format for quick comparison. Last, a quick method will be presented to estimate as fabricated piping costs if the base material price for pipe is known.

  10. 46 CFR 111.01-11 - Corrosion-resistant parts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Corrosion-resistant parts. 111.01-11 Section 111.01-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-11 Corrosion-resistant parts. Each enclosure and part of...

  11. Magnesium alloys and graphite wastes encapsulated in cementitious materials: Reduction of galvanic corrosion using alkali hydroxide activated blast furnace slag.

    PubMed

    Chartier, D; Muzeau, B; Stefan, L; Sanchez-Canet, J; Monguillon, C

    2017-03-15

    Magnesium alloys and graphite from spent nuclear fuel have been stored together in La Hague plant. The packaging of these wastes is under consideration. These wastes could be mixed in a grout composed of industrially available cement (Portland, calcium aluminate…). Within the alkaline pore solution of these matrixes, magnesium alloys are imperfectly protected by a layer of Brucite resulting in a slow corrosion releasing hydrogen. As the production of this gas must be considered for the storage safety, and the quality of wasteform, it is important to select a cement matrix capable of lowering the corrosion kinetics. Many types of calcium based cements have been tested and most of them have caused strong hydrogen production when magnesium alloys and graphite are conditioned together because of galvanic corrosion. Exceptions are binders based on alkali hydroxide activated ground granulated blast furnace slag (BFS) which are presented in this article.

  12. Superhydrophobic copper surfaces fabricated by fatty acid soaps in aqueous solution for excellent corrosion resistance

    NASA Astrophysics Data System (ADS)

    Xu, Wenlong; Hu, Yuanyuan; Bao, Wenda; Xie, Xiaoyu; Liu, Yiran; Song, Aixin; Hao, Jingcheng

    2017-03-01

    A simple and safe one-step immersion method was developed to obtain the stable superhydrophobic copper surfaces with excellent corrosion resistance ability using fatty acids in water-medium instead of ethanol. An organic alkali, N,N-dimethylcyclohexylamine (DMCHA), was chosen to solve the poor solubility of fatty acids in water and the high Krafft point of carboxylate salts with inorganic counterions. The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol (more than 2 d), which is universally feasible for the fabrication of superhydrophobic metal surfaces in industry scale, thereby greatly increasing the safety in industrial manufacture.

  13. Hot corrosion resistance of nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.; Barret, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloys was examined by cyclically oxidizing sodium sulfate-coated specimens in still air at 900, 1000, and 1100 C. The compositions tested were within the ternary region: Ni, Ni-50 at.% Cr, and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. From these equations corrosion isopleths were prepared. Compositional regions with the best hot corrosion resistance were identified.

  14. Hot corrosion resistance of nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.; Barrett, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloy was examined by cyclically oxidizing sodium sulfate coated specimens in still air at 900, 1000 and 1100 C. The compositions tested were within the ternary region: Ni; Ni-50 at.% Cr; and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. Corrosion isopleths were prepared from these equations. Compositional regions with the best hot corrosion resistance were identified.

  15. Formation of Surface Corrosion-Resistant Nanocrystalline Structures on Steel.

    PubMed

    Nykyforchyn, Hryhoriy; Kyryliv, Volodymyr; Maksymiv, Olha; Slobodyan, Zvenomyra; Tsyrulnyk, Oleksandr

    2016-12-01

    Engineering materials with nanocrystalline structure could be exploited under simultaneous action of mechanical loading and corrosion environments; therefore, their corrosion resistance is important. Surface nanocrystalline structure was generated on middle carbon steels by severe plastic deformation using the method of mechanical pulse friction treatment. This treatment additionally includes high temperature phase transformation and alloying. Using a complex of the corrosive, electrochemical and physical investigations, it was established that nanocrystalline structures can be characterized by lower or increased corrosion resistance in comparison with the reference material. It is caused by the action of two confronting factors: arising energy level and anticorrosive alloying of the surface layer.

  16. Chromate-free corrosion resistant conversion coatings for aluminum

    SciTech Connect

    Buchheit, R.G. ); Stoner, G.E. . Dept. of Materials Science and Engineering)

    1993-01-01

    We have developed a method for generating chromate-free corrosion resistant coatings on aluminum alloys using a process procedurally similar to standard chromate conversion. These coatings provide good corrosion resistance on 6061-T6 and 1100 A1 under salt spray testing conditions. The resistance of the new coating is comparable to that of chromate conversion coatings in four point probe tests, but higher when a mercury probe technique is used. Initial tests of paint adhesion, and under paint corrosion resistance are promising. Primary advantage of this new process is that no hazardous chemicals are used or produced during the coating operation.

  17. Chromate-free corrosion resistant conversion coatings for aluminum

    SciTech Connect

    Buchheit, R.G.; Stoner, G.E.

    1993-03-01

    We have developed a method for generating chromate-free corrosion resistant coatings on aluminum alloys using a process procedurally similar to standard chromate conversion. These coatings provide good corrosion resistance on 6061-T6 and 1100 A1 under salt spray testing conditions. The resistance of the new coating is comparable to that of chromate conversion coatings in four point probe tests, but higher when a mercury probe technique is used. Initial tests of paint adhesion, and under paint corrosion resistance are promising. Primary advantage of this new process is that no hazardous chemicals are used or produced during the coating operation.

  18. Shop fabricated corrosion-resistant underground storage tanks

    SciTech Connect

    Geyer, W.B.; Stellmach, W.A.

    1995-12-31

    Integral corrosion resistance has long been incorporated into shop fabricated steel underground storage tank design. Since 1969, an industry standard has been the sti-P{sub 3}{reg_sign} (P3) tank. However, the past decade has seen the development of several alternative corrosion resistant and secondary containment technologies. Fiberglass-coated steel composite tanks, and jacketed tanks utilizing various materials as a secondary wall, provide corrosion resistance without the cathodic protection monitoring requirements mandated by the EPA for single-wall P3 tanks. On the other hand, the P3 tank is the only tank technology commonly marketed today with an integral ability to verify its corrosion resistance over the life of the tank. Many existing USTs remain to be replaced or upgraded with corrosion resistance (and other requirements) by the end of 1998. Steel tanks built and installed prior to the advent of pre-engineered, factory-supplied protection against corrosion can be retrofitted with cathodic protection or can be internally lined. Specific installation standards developed by the steel tank industry and the petroleum industry must be followed so as to assure the integrity of the various corrosion resistant technologies developed by the Steel Tank Institute. The technologies describes in this paper will ensure compliance with the corrosion protection requirements of new storage tanks.

  19. Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

    DOEpatents

    Liu, C.T.; McKamey, C.G.; Tortorelli, P.F.; David, S.A.

    1994-06-14

    The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium. 9 figs.

  20. Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

    DOEpatents

    Liu, Chain T.; McKamey, Claudette G.; Tortorelli, Peter F.; David, Stan A.

    1994-01-01

    The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium.

  1. High performance corrosion-resistant structural steels

    SciTech Connect

    Fletcher, F.B.; Ferry, B.N.; Beblo, D.G.

    1995-12-31

    A new corrosion-resistant structural steel named Duracorr was developed for low maintenance when compared to conventional structural steels. The new stainless steel is a dual phase composition between the established 12% Cr, ferritic T409 and martensitic T410 grades. Attractive combinations of hardness, strength, toughness, weldability and formability are derived from a microstructure that is a dual phase mixture of ferrite and martensite. The Duracorr composition, UNS S41003, provides for a microstructure of ferrite and austenite to be present throughout the hot rolling process. Cooling to room temperature causes transformation of the austenite to martensite. Subsequent tempering of the steel creates minimum mechanical properties of 275 MPa (40 ksi) yield strength and 455 MPa (66 ksi) tensile strength with room temperature longitudinal Charpy impact values typically greater than 34 J (25 ft-lbs).

  2. Corrosion resistance of polyurethane-coated nitinol cardiovascular stents.

    PubMed

    Mazumder, M M; De, S; Trigwell, S; Ali, N; Mazumder, M K; Mehta, J L

    2003-01-01

    Corrosion of metal stents implanted inside an artery can have two adverse effects: (1) tissue reaction and possible toxic effects from the metal ions leaching out of the stent, and (2) loss of mechanical strength of the stent caused by corrosion. The corrosion resistance of Nitinol (Nickel-Titanium) stents and its modulation with different film thickness of polymer coating was studied against an artificial physiological solution using a Potentiostat/Galvanostat and an electrochemical corrosion cell. The corrosion rate decreased rapidly from 275 microm/year for an uncoated surface down to less than 13 microm/year for a 30 microm thick polyurethane coating. Stainless steel (316L) and Nitinol both contain potentially toxic elements, and both are subject to stress corrosion. Minimization of corrosion can significantly reduce both tissue reaction and structural degradation.

  3. Alkali-Resistant Mechanism of a Hollandite DeNOx Catalyst.

    PubMed

    Hu, Pingping; Huang, Zhiwei; Gu, Xiao; Xu, Fei; Gao, Jiayi; Wang, Yue; Chen, Yaxin; Tang, Xingfu

    2015-06-02

    A thorough understanding of the deactivation mechanism by alkalis is of great importance for rationally designing improved alkali-resistant deNOx catalysts, but a traditional ion-exchange mechanism cannot often accurately describe the nature of the deactivation, thus hampering the development of superior catalysts. Here, we establish a new exchange-coordination mechanism on the basis of the exhaustive study on the strong alkali resistance of a hollandite manganese oxide (HMO) catalyst. A combination of isothermal adsorption measurements of ammonia with X-ray absorption near-edge structure spectra and X-ray photoelectron spectra reveals that alkali metal ions first react with protons from Brønsted acid sites of HMO via the ion exchange. Synchrotron X-ray diffraction patterns and extended X-ray absorption fine structure spectra coupled with theoretical calculations demonstrate that the exchanged alkali metal ions are subsequently stabilized at size-suitable cavities in the HMO pores via a coordination model with an energy savings. This exchange-coordination mechanism not only gives a wholly convincing explanation for the intrinsic nature of the deactivation of the reported catalysts by alkalis but also provides a strategy for rationally designing improved alkali-resistant deNOx catalysts in general.

  4. Alkali- and Sulfur-Resistant Tungsten-Based Catalysts for NOx Emissions Control.

    PubMed

    Huang, Zhiwei; Li, Hao; Gao, Jiayi; Gu, Xiao; Zheng, Li; Hu, Pingping; Xin, Ying; Chen, Junxiao; Chen, Yaxin; Zhang, Zhaoliang; Chen, Jianmin; Tang, Xingfu

    2015-12-15

    The development of catalysts with simultaneous resistance to alkalis and sulfur poisoning is of great importance for efficiently controlling NOx emissions using the selective catalytic reduction of NOx with NH3 (SCR), because the conventional V2O5/WO3-TiO2 catalysts often suffer severe deactivation by alkalis. Here, we support V2O5 on a hexagonal WO3 (HWO) to develop a V2O5/HWO catalyst, which has exceptional resistance to alkali and sulfur poisoning in the SCR reactions. A 350 μmol g(-1) K(+) loading and the presence of 1,300 mg m(-3) SO2 do not almost influence the SCR activity of the V2O5/HWO catalyst, and under the same conditions, the conventional V2O5/WO3-TiO2 catalysts completely lost the SCR activity within 4 h. The strong resistance to alkali and sulfur poisoning of the V2O5/HWO catalysts mainly originates from the hexagonal structure of the HWO. The HWO allows the V2O5 to be highly dispersed on the external surfaces for catalyzing the SCR reactions and has the relatively smooth surfaces and the size-suitable tunnels specifically for alkalis' diffusion and trapping. This work provides a useful strategy to develop SCR catalysts with exceptional resistance to alkali and sulfur poisoning for controlling NOx emissions from the stationary source and the mobile source.

  5. Effect of moisture on corrosion of Ni-based alloys in molten alkali fluoride FLiNaK salt environments

    NASA Astrophysics Data System (ADS)

    Ouyang, Fan-Yi; Chang, Chi-Hung; You, Bo-Chien; Yeh, Tsung-Kuang; Kai, Ji-Jung

    2013-06-01

    We investigated the corrosion characteristics on several selected alloys at 600 and 700 °C in FLiNaK molten salts with different moisture contents. Hastelloys-N and Hastelloys-B3 exhibited better corrosion resistances, while Haynes 263 showed the poorest corrosion resistance. The mass loss of the tested alloys is primarily determined by the purity of FLiNaK salts; however, the effect of temperature becomes more important on the mass loss of the tested alloys in the non-purified FLiNaK salts. When the residual moisture is present in the FLiNaK salts, the mass losses of the tested alloys varied linearly with original Cr content plus one-third of Mo content. The results of structural characterization revealed that the tested alloys in the FLiNaK salts with higher moisture content would aggravate intergranular corrosion and pitting.

  6. Corrosion-electrochemical behavior of zirconium in molten alkali metal carbonates

    NASA Astrophysics Data System (ADS)

    Nikitina, E. V.

    2016-08-01

    The corrosion and electrochemical characteristics of zirconium during its interaction with molten lithium, sodium, and potassium carbonates containing from 1 to 5 wt % additives to the salt phase are studied in a temperature range of 500-800°C using gravimetry, corrosion potential measurement, and anodic polarization. The substances decreasing the corrosion losses due to the strengthening and thickening of an oxide film (lithium, sodium, potassium hydroxides) are used as passivators. Sodium chloride, fluoride, and sulfate serve as corrosion stimulators (activators).

  7. Controlled ferrite content improves weldability of corrosion-resistant steel

    NASA Technical Reports Server (NTRS)

    Malin, C. O.

    1967-01-01

    Corrosion-resistant steel that adds restrictions on chemical composition to ensure sufficient ferrite content decreases the tendency of CRES to develop cracks during welding. The equations restricting composition are based on the Schaeffler constitution diagram.

  8. Durable Corrosion and Ultraviolet-Resistant Silver Mirror

    DOEpatents

    Jorgensen, G. J.; Gee, R.

    2006-01-24

    A corrosion and ultra violet-resistant silver mirror for use in solar reflectors; the silver layer having a film-forming protective polymer bonded thereto, and a protective shield overlay comprising a transparent multipolymer film that incorporates a UV absorber. The corrosion and ultraviolet resistant silver mirror retains spectral hemispherical reflectance and high optical clarity throughout the UV and visible spectrum when used in solar reflectors.

  9. Plastic deformation effect of the corrosion resistance in case of austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Haraszti, F.; Kovacs, T.

    2017-02-01

    The corrosion forms are different in case of the austenitic steel than in case of carbon steels. Corrosion is very dangerous process, because that corrosion form is the intergranular corrosion. The austenitic stainless steel shows high corrosion resistance level. It knows that plastic deformation and the heat treating decrease it’s resistance. The corrosion form in case of this steel is very special and the corrosion tests are difficult. We tested the selected steel about its corrosion behaviour after high rate deformation. We wanted to find a relationship between the corrosion resistance decreasing and the rate of the plastic deformation. We wanted to show this behaviour from mechanical and electrical changing.

  10. Localized corrosion and stress corrosion cracking resistance of friction stir welded aluminum alloy 5454

    SciTech Connect

    Frankel, G.S.; Xia, Z.

    1999-02-01

    The susceptibility of welded and unwelded samples of Al 5454 (UNS A95454) in the -O and -H34 tempers to pitting corrosion and stress corrosion cracking (SCC) in chloride solutions was studied. Welded samples were fabricated using the relatively new friction stir welding (FSW) process as well as a standard gas-tungsten arc welding process for comparison. Pitting corrosion was assessed through potentiodynamic polarization experiments. U-bend and slow strain rate tests were used to determine SCC resistance. The FSW samples exhibited superior resistance to pitting corrosion compared to the base metal and arc-welded samples. U-bend tests indicated adequate SCC resistance for the FSW samples. However, the FSW samples exhibited discontinuities that probably were associated with remnant boundaries of the original plates. These defects resulted in intermittent increased susceptibility to pitting and, particularly for Al 5454-H34 samples, poor mechanical properties in general.

  11. [Socio-medical significance of alkalie resistance, alkalie neutralization and skin-surface lipid content in atopic neurodermatitis and ichthyosis vulgaris (author's transl)].

    PubMed

    Schnyder, U W; Gloor, M; Taugner, M

    1977-01-01

    In individuals free from skin diseases, the resistance and the neutralisation to alkali, and the quantity of lipids at the surface of the skin, are constitltional factors; these idiotypically (genetically) controlled factors are subject to paratypical (environmental) variations. The frequency of a reduced alkali neutralisation and of sebostasis in case of neurodermitis atopica and of ichthyosis vulgaris is not dealt with in the literature, but it results from literature findings that a pathologic alkali resistance is a facultative feature in neurodermitis atopica, while it is an obligatory one in ichthyosis vulgaris. The difference seems to be conditioned genetically. In neurodermitis atopica, the genotype is in itself of no pathogenic importance since the disease is induced exclusively by exogenous and endogenous, non hereditary agents. In ichthyosis vulgaris, the reduced alkali resistance falls into the pleiotropic character of the disease.

  12. High Temperature Alkali Corrosion of Dense SN4 Coated with CMZP and Mg-Doped A21TiO5 in Coal Gas

    SciTech Connect

    J. J. Brown; Nguyen Thierry

    1997-10-01

    Si3N4 heat exchangers used in industrial systems are usually operating in harsh environments. Not only is this structural material experiencing high temperatures, but it is also subjected to corrosive gases and condensed phases. Past studies have demonstrated that condensed phases severely attack Si3N4 and as a consequence, dramatically reduce its lifetime in industrial operating systems.1,2 Previous research conducted at Virginia Tech on low thermal expansion coefficient oxide ceramics,3,4,5 (Ca1-X,MgX)Zr4(PO4)6 (CMZP), and Mg-doped Al2TiO5, for structural application have shown that these two materials exhibited better resistance to alkaline corrosion than Si3N4. Thus, they were envisioned as good candidates for a protective coating on Si3N4 heat exchangers. As a result, the goal of the present work is to develop CMZP and Mg-doped Al2TiO5 protective thin films using the sol-gel process and the dip coating technique and to test their effectiveness in an alkali-containing atmosphere.

  13. Task 6.6 - Sialon Coatings for Alkali-Resistant Silicon Nitride: Semi-annual report, July 1-December 31, 1996

    SciTech Connect

    Nowok, J.W.

    1997-12-31

    The efficiency of a gas turbine can be improved by increasing operating temperature. Construction materials should meet both high strength requirements and hot-alkali corrosion resistance. Structural ceramics based on silicon nitride are promising candidates for high temperature engineering applications because of their high strength and good resistance to corrosion. Their performance varies significantly with the mechanical properties of boundary phases which, in turn, depend on their chemical composition, thickness of the amorphous phase, and the deformation process. To make silicon nitride ceramics tough, SiAlON ceramics were developed with controlled crystallization of the amorphous grain boundary phase. Crystallization of the grain boundary glass improves the high temperature mechanical properties of silicon nitride ceramics.

  14. Towards Long-Term Corrosion Resistance in FE Service Environments

    SciTech Connect

    G. R. Holcomb and P. Wang

    2010-10-01

    The push for carbon capture and sequestration for fossil fuel energy production has materials performance challenges in terms of high temperature oxidation and corrosion resistance. Such challenges will be illustrated with examples from several current technologies that are close to being realized. These include cases where existing technologies are being modified—for example fireside corrosion resulting from increased corrosivity of flue gas in coal boilers refit for oxy-fuel combustion, or steam corrosion resulting from increased temperatures in advanced ultra supercritical steam boilers. New technology concepts also push the high temperature corrosion and oxidation limits—for example the effects of multiple oxidants during the use of high CO2 and water flue gas used as turbine working fluids.

  15. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    SciTech Connect

    Sugama, T.; Pyatina, T.

    2014-11-14

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  16. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    SciTech Connect

    Sugama, T.; Pyatina, T.

    2014-11-01

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  17. Impurity control and corrosion resistance of magnesium-aluminum alloy

    SciTech Connect

    Liu, M.; Song, GuangLing

    2013-01-01

    The corrosion resistance of magnesium alloys is very sensitive to the contents of impurity elements such as iron. In this study, a series of diecast AXJ530 magnesium alloy samples were prepared with additions of Mn and Fe. Through a comprehensive phase diagram calculation and corrosion evaluation, the mechanisms for the tolerance limit of Fe in magnesium alloy are discussed. This adds a new dimension to control the alloying impurity in terms of alloying composition design and casting conditions.

  18. Design strategies for development of SCR catalyst: improvement of alkali poisoning resistance and novel regeneration method.

    PubMed

    Peng, Yue; Li, Junhua; Shi, Wenbo; Xu, Jiayu; Hao, Jiming

    2012-11-20

    Based on the ideas of the additives modification and regeneration method update, two different strategies were designed to deal with the traditional SCR catalyst poisoned by alkali metals. First, ceria doping on the V(2)O(5)-WO(3)/TiO(2) catalyst could promote the SCR performance even reducing the V loading, which resulted in the enhancement of the catalyst's alkali poisoning resistance. Then, a novel method, electrophoresis treatment, was employed to regenerate the alkali poisoned V(2)O(5)-WO(3)/TiO(2) catalyst. This novel technique could dramatically enhance the SCR activities of the alkali poisoned catalysts by removing approximately 95% K or Na ions from the catalyst and showed less hazardous to the environment. Finally, the deactivation mechanisms by the alkali metals were extensively studied by employing both the experimental and DFT theoretical approaches. Alkali atom mainly influences the active site V species rather than W oxides. The decrease of catalyst surface acidity might directly reduce the catalytic activity, while the reducibility of catalysts could be another important factor.

  19. Removal of oxides from alkali metal melts by reductive titration to electrical resistance-change end points

    DOEpatents

    Tsang, Floris Y.

    1980-01-01

    Alkali metal oxides dissolved in alkali metal melts are reduced with soluble metals which are converted to insoluble oxides. The end points of the reduction is detected as an increase in electrical resistance across an alkali metal ion-conductive membrane interposed between the oxide-containing melt and a material capable of accepting the alkali metal ions from the membrane when a difference in electrical potential, of the appropriate polarity, is established across it. The resistance increase results from blocking of the membrane face by ions of the excess reductant metal, to which the membrane is essentially non-conductive.

  20. Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys

    SciTech Connect

    Rebak, R B; Day, S D; Lian, T; Aprigliano, L F; Hailey, P D; Farmer, J C

    2007-02-18

    Iron-based amorphous alloys possess enhanced hardness and are highly resistant to corrosion, which make them desirable for wear applications in corrosive environments. It was of interest to examine the behavior of amorphous alloys during anodic polarization in concentrated salt solutions and in the salt-fog testing. Results from the testing of one amorphous material (SAM2X5) both in ribbon form and as an applied coating are reported here. Cyclic polarization tests were performed on SAM2X5 ribbon as well as on other nuclear engineering materials. SAM2X5 showed the highest resistance to localized corrosion in 5 M CaCl{sub 2} solution at 105 C. Salt fog tests of 316L SS and Alloy 22 coupons coated with amorphous SAM2X5 powder showed resistance to rusting. Partial devitrification may be responsible for isolated pinpoint rust spots in some coatings.

  1. Alkali-Resistant Quasi-Solid-State Electrolyte for Stretchable Supercapacitors.

    PubMed

    Tang, Qianqiu; Wang, Wenqiang; Wang, Gengchao

    2016-10-05

    Research on stretchable energy-storage devices has been motivated by elastic electronics, and considerable research efforts have been devoted to the development of stretchable electrodes. However, stretchable electrolytes, another critical component in stretchable devices, have earned quite little attention, especially the alkali-resistant ones. Here, we reported a novel stretchable alkali-resistant electrolyte made of a polyolefin elastomer porous membrane supported potassium hydroxide-potassium polyacrylate (POE@KOH-PAAK). The as-prepared electrolyte shows a negligible plastic deformation even after 1000 stretching cycles at a strain of 150% as well as a high conductivity of 0.14 S cm(-1). It also exhibits excellent alkali resistance, which shows no obvious degradation of the mechanical performance after immersion in 2 M KOH for up to 2 weeks. To demonstrate its good properties, a high-performance stretchable supercapacitor is assembled using a carbon-nanotube-film-supported NiCo2O4 (CNT@NiCo2O4) as the cathode and Fe2O3 (CNT@Fe2O3) as the anode, proving great application promise of the stretchable alkali-resistant electrolyte in stretchable energy-storage devices.

  2. Corrosion resistance of porous NiTi biomedical alloy in simulated body fluids

    NASA Astrophysics Data System (ADS)

    Stergioudi, F.; Vogiatzis, C. A.; Pavlidou, E.; Skolianos, S.; Michailidis, N.

    2016-09-01

    The corrosion performance of two porous NiTi in physiological and Hank’s solutions was investigated by potentiodynamic polarization, cyclic polarization and impedance spectroscopy. Electric models simulating the corrosion mechanism at early stages of immersion were proposed, accounting for both microstructural observations and electrochemical results. Results indicate that both porous samples were susceptible to localized corrosion. The porosity increase (from 7% to 18%) resulted in larger and wider pore openings, thus favoring the corrosion resistance of 18% porous NiTi. Strengthening of corrosion resistance was observed in Hank’s solution. The pore morphology and micro-galvanic corrosion phenomena were determining factors affecting the corrosion resistance.

  3. Corrosion-resistant iridium-platinum anode material for high polarization application in corrosive acids

    SciTech Connect

    Farmer, J.; Summers, L.; Lewis, P.

    1993-09-08

    The present invention relates to highly corrosion resistant components for use in an electrochemical cell. Specifically, these components are resistant to corrosion under very extreme conditions such as exposure to aqua regia in the presence of a constant current density of 100mA/m{sup 2}. The components are comprised of an iridium-platinum alloy that comprises less than 30% iridium. In a preferred embodiment of the present invention, the iridium-platinum alloy comprises 15-20% iridium. In another preferred embodiment of the present invention, the iridium-platinum alloy is deposited on the surface of an electrochemical cell component by magnetron sputtering. The present invention also relates to a method for conducting an electrochemical reaction in the presence of highly corrosive acids under a high degree of polarization wherein the electrochemical cell comprises a component, preferably the anode, containing an iridium-platinum alloy that comprises less than 30% iridium.

  4. High-temperature corrosion resistance of ceramics and ceramic coatings

    SciTech Connect

    Tortorelli, P.F.

    1996-06-01

    Ceramics and ceramic composites offer the potential to operate fossil energy systems at the higher temperatures necessary for improved energy efficiency and better environmental control. However, because many fossil fuel-derived processes contain sulfur, chlorine, and carbon, as well as oxygen, degradation from high-temperature corrosion and environmental effects arising from reactions of solids with gases and condensable products is a common life-determining factor in operating systems. Ceramic-based products are not immune to such degradation; adequate corrosion resistance must be assured to exploit the technical and economic potential of such materials. This is normally accomplished by using stable, sound oxides that exist in their bulk form, that naturally grow as surface layers upon exposure to an oxidizing environment, or that are deposited as a coating on a susceptible material. It is therefore important to examine the critical issues with respect to more environmental stability of ceramics that have the potential to be corrosion resistant in particular fossil environments. Key aspects include not only chemical compatibility, but the influence of the environment on the mechanical behavior of the ceramic materials. In addition, for coatings, the mechanical reliability of the ceramic is a key issue in that an otherwise corrosion-resistant surface layer must remain sound and adherent in order to provide protection to the underlying substrate. The purpose of this work is to support the development of advanced ceramics and ceramic composites for applications in fossil environments by examining critical issues related to high-temperature corrosion resistance. More specifically, the overall objective of this task is to examine the chemical compatibility and reliability of potentially corrosion-resistant ceramics being developed as protective overcoats and/or structural materials as parts of other work elements funded by the AR&TD Program.

  5. Corrosion resistance characterization of porous alumina membrane supports

    SciTech Connect

    Dong Yingchao; Lin Bin; Zhou Jianer; Zhang Xiaozhen; Ling Yihan; Liu Xingqin; Meng Guangyao; Hampshire, Stuart

    2011-04-15

    Tubular porous alumina ceramic membrane supports were fabricated by an extrusion-drying-sintering process and then characterized in detail in terms of corrosion resistance in both H{sub 2}SO{sub 4} and NaOH aqueous solutions. Variations in the properties of the alumina supports such as mass loss percent, mechanical strength, open porosity and pore size distribution were studied before and after corrosion under different conditions. In addition, the microstructures were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction before and after corrosion. The fabricated porous alumina supports offer possibilities for some potential applications as micro-filtration or ultra-filtration membrane supports, as well as in the pre-treatment of strongly acidic industrial waste-liquids. - Research highlights: {yields} Porous alumina membrane supports fabricated by extrusion-drying-sintering process. {yields} Corrosion resistance in 20 wt.% H{sub 2}SO{sub 4} and 1, 5, 10 wt.% NaOH aqueous solutions. {yields} Rapid mass loss and loss of flexural strength occurred in hot NaOH solution. {yields} Resistant to strong acid corrosion with low mass loss, low flexural strength loss. {yields} Porous alumina supports have potential for treatment of strong acid waste liquids.

  6. Corrosion-resistant, electrically-conductive plate for use in a fuel cell stack

    DOEpatents

    Carter, J. David; Mawdsley, Jennifer R.; Niyogi, Suhas; Wang, Xiaoping; Cruse, Terry; Santos, Lilia

    2010-04-20

    A corrosion resistant, electrically-conductive, durable plate at least partially coated with an anchor coating and a corrosion resistant coating. The corrosion resistant coating made of at least a polymer and a plurality of corrosion resistant particles each having a surface area between about 1-20 m.sup.2/g and a diameter less than about 10 microns. Preferably, the plate is used as a bipolar plate in a proton exchange membrane (PEMFC) fuel cell stack.

  7. Fretting corrosion resistance and fretting corrosion product cytocompatibility of ferritic stainless steel.

    PubMed

    Xulin, S; Ito, A; Tateishi, T; Hoshino, A

    1997-01-01

    To avoid nickel ion release from SUS317L as an implant material, a new type of nickel, commercially free, of high purity, and high chromium ferritic stainless steel, was developed. The new stainless steel (FJ) was studied for aspects of fretting corrosion and cytocompatibility compared with SUS317L. A pin-on-plate fretting corrosion test in an artificial physiologic solution, and cell culture in media with the addition of the artificial physiologic solution used for fretting was conducted. Resistance to the fretting induced crevice corrosion of FJ was higher than that of SUS317L because of the favorable electrochemical stability of the FJ alloy. The amount of iron ion or colloidal fine particles released from FJ was about a quarter of that from SUS317L, although the weight loss of a pin of FJ was almost 5/3 that of SUS317L. The artificial physiologic solution used for SUS317L fretting was more harmful to the growth of L929 and MC3T3-E1 cells than that used for FJ fretting. FJ was therefore superior to SUS317L as a biomaterial, judging from the resistance to fretting-induced crevice corrosion, electrochemical stability, and the cytocompatibility of fretting corrosion products.

  8. 78 FR 15376 - Determinations: Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-11

    ... COMMISSION Determinations: Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea On the basis...)), that revocation of the countervailing duty order on corrosion-resistant carbon steel flat products from Korea and the antidumping duty orders on corrosion-resistant carbon steel flat products from Germany...

  9. 49 CFR 179.201-5 - Postweld heat treatment and corrosion resistance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Postweld heat treatment and corrosion resistance....201-5 Postweld heat treatment and corrosion resistance. (a) Tanks and attachments welded directly... tested to demonstrate that they possess the corrosion resistance specified in § 179.200-7(d), Footnote...

  10. 49 CFR 179.201-5 - Postweld heat treatment and corrosion resistance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Postweld heat treatment and corrosion resistance....201-5 Postweld heat treatment and corrosion resistance. (a) Tanks and attachments welded directly... tested to demonstrate that they possess the corrosion resistance specified in § 179.200-7(d), Footnote...

  11. 49 CFR 179.201-5 - Postweld heat treatment and corrosion resistance.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Postweld heat treatment and corrosion resistance....201-5 Postweld heat treatment and corrosion resistance. (a) Tanks and attachments welded directly... tested to demonstrate that they possess the corrosion resistance specified in § 179.200-7(d), Footnote...

  12. 49 CFR 179.201-5 - Postweld heat treatment and corrosion resistance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Postweld heat treatment and corrosion resistance....201-5 Postweld heat treatment and corrosion resistance. (a) Tanks and attachments welded directly... tested to demonstrate that they possess the corrosion resistance specified in § 179.200-7(d), Footnote...

  13. 49 CFR 179.201-5 - Postweld heat treatment and corrosion resistance.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Postweld heat treatment and corrosion resistance....201-5 Postweld heat treatment and corrosion resistance. (a) Tanks and attachments welded directly... tested to demonstrate that they possess the corrosion resistance specified in § 179.200-7(d), Footnote...

  14. High temperature, low expansion, corrosion resistant ceramic and gas turbine

    DOEpatents

    Rauch, Sr., Harry W.

    1981-01-01

    The present invention relates to ZrO.sub.2 -MgO-Al.sub.2 O.sub.3 -SiO.sub.2 ceramic materials having improved thermal stability and corrosion resistant properties. The utilization of these ceramic materials as heat exchangers for gas turbine engines is also disclosed.

  15. Laser surface melting of aluminium alloy 6013 for improving stress corrosion and corrosion fatigue resistance

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Long

    Laser surface treatment of aluminium alloy 6013, a relatively new high strength aluminium alloy, was conducted with the aim of improving the alloy's resistance to stress corrosion cracking and corrosion fatigue. In the first phase of this research, laser surface melting (LSM) of the alloy was conducted using an excimer laser. The microstructural changes induced by the laser treatment were studied in detail and characterised. The results showed that excimer LSM produced a relatively thin, non-dentritic planar re-melted layer which is largely free of coarse constituent particles and precipitates. The planar growth phenomenon was explained using the high velocity and high temperature gradient absolute stability criteria. The structure of the oxide and/or the nitride bearing film at the outmost surface of the re-melted layer was also characterised. The results of the electrochemical tests showed that the pitting corrosion resistance of the alloy could be greatly increased by excimer laser melting, especially when the alloy was treated in nitrogen gas: the corrosion current density of the N2-treated specimen was some two orders of magnitude lower than that of the air-treated specimen which was one order of magnitude lower than that of the untreated specimen. The effect of the outer surface oxide and/or nitride bearing film per se on pitting corrosion resistance was determined. The results of a Mott - Schottky analysis strongly suggest that the outer surface film, which exhibited the nature of an n-type semiconductor was responsible for the significant improvement of the corrosion resistance of the laser-treated material. Furthermore, the corrosion response of the surface film was modelled using equivalent circuits. Based on the results of the slow strain rate tensile (SSRT) and corrosion fatigue tests, the stress corrosion cracking and pitting corrosion fatigue behaviour of the excimer laser treated material was evaluated. The results of the SSRT test showed that, in

  16. The evaluation of corrosion resistant rod end rolling element bearings

    SciTech Connect

    Braza, J.F.; Giuntoli, K.; Imundo, J.R.

    1998-12-31

    Recent developments on carburizing grades of stainless steels have provided new materials to produce corrosion resistant airframe control bearings. This paper presents the application of one of these new carburizing grades of stainless steel to rod end ball bearings. The outer ring of the rod end bearing is made out of carburized stainless steel, while the inner ring and balls are made out of through-hardened stainless steel. The stainless steel rod end bearings were evaluated according to various ASTM and Military specifications for performance and corrosion resistance. The stainless steel rod end bearings exceeded the performance requirements of standard rod end bearings (which are comprised of a carburized 8620 steel outer ring and 52100 steel inner ring and balls) in accordance with MIL-B-6039. The rod end bearings were evaluated in the radial fracture load, axial fracture load, and radial dynamic load tests. Also, salt spray and alternate immersion corrosion tests (ASTM B 117-85 and G 44-88, respectively) were conducted on the stainless steel rod end bearings. The stainless steel rod end bearings exhibited superior corrosion resistance to the standard 8620/52100 steel rod end bearings.

  17. Corrosion resistance of kolsterised austenitic 304 stainless steel

    SciTech Connect

    Abudaia, F. B. Khalil, E. O. Esehiri, A. F. Daw, K. E.

    2015-03-30

    Austenitic stainless suffers from low wear resistance in applications where rubbing against other surfaces is encountered. This drawback can be overcome by surface treatment such as coating by hard materials. Other treatments such as carburization at relatively low temperature become applicable recently to improve hardness and wear resistance. Carburization heat treatment would only be justified if the corrosion resistance is unaffected. In this work samples of 304 stainless steels treated by colossal supersaturation case carburizing (known as Kolsterising) carried out by Bodycote Company was examined for pitting corrosion resistance at room temperature and at 50 °C. Comparison with results obtained for untreated samples in similar testing conditions show that there is no deterioration in the pitting resistance due to the Kolsterising heat treatment. X ray diffraction patterns obtained for Kolsterising sample showed that peaks correspond to the austenite phase has shifted to lower 2θ values compared with those of the untreated sample. The shift is an indication for expansion of austenite unit cells caused by saturation with diffusing carbon atoms. The XRD of Kolsterising samples also revealed additional peaks appeared in the patterns due to formation of carbides in the kolsterised layer. Examination of these additional peaks showed that these peaks are attributed to a type of carbide known as Hagg carbide Fe{sub 2}C{sub 5}. The absence of carbides that contain chromium means that no Cr depletion occurred in the layer and the corrosion properties are maintained. Surface hardness measurements showed large increase after Kolsterising heat treatment.

  18. Corrosion resistance of kolsterised austenitic 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Abudaia, F. B.; Khalil, E. O.; Esehiri, A. F.; Daw, K. E.

    2015-03-01

    Austenitic stainless suffers from low wear resistance in applications where rubbing against other surfaces is encountered. This drawback can be overcome by surface treatment such as coating by hard materials. Other treatments such as carburization at relatively low temperature become applicable recently to improve hardness and wear resistance. Carburization heat treatment would only be justified if the corrosion resistance is unaffected. In this work samples of 304 stainless steels treated by colossal supersaturation case carburizing (known as Kolsterising) carried out by Bodycote Company was examined for pitting corrosion resistance at room temperature and at 50 °C. Comparison with results obtained for untreated samples in similar testing conditions show that there is no deterioration in the pitting resistance due to the Kolsterising heat treatment. X ray diffraction patterns obtained for Kolsterising sample showed that peaks correspond to the austenite phase has shifted to lower 2θ values compared with those of the untreated sample. The shift is an indication for expansion of austenite unit cells caused by saturation with diffusing carbon atoms. The XRD of Kolsterising samples also revealed additional peaks appeared in the patterns due to formation of carbides in the kolsterised layer. Examination of these additional peaks showed that these peaks are attributed to a type of carbide known as Hagg carbide Fe2C5. The absence of carbides that contain chromium means that no Cr depletion occurred in the layer and the corrosion properties are maintained. Surface hardness measurements showed large increase after Kolsterising heat treatment.

  19. Selection of Corrosion Resistant Materials for Nuclear Waste Repositories

    SciTech Connect

    R.B. Rebak

    2006-08-28

    Several countries are considering geological repositories to dispose of nuclear waste. The environment of most of the currently considered repositories will be reducing in nature, except for the repository in the US, which is going to be oxidizing. For the reducing repositories, alloys such as carbon steel, stainless steels and titanium are being evaluated. For the repository in the US, some of the most corrosion resistant commercially available alloys are being investigated. This paper presents a summary of the behavior of the different materials under consideration for the repositories and the current understanding of the degradation modes of the proposed alloys in ground water environments from the point of view of general corrosion, localized corrosion and environmentally assisted cracking.

  20. Selection of Corrosion Resistant Materials for Nuclear Waste Repositories

    SciTech Connect

    Rebak, R B

    2006-06-01

    Several countries are considering geological repositories to dispose of nuclear waste. The environment of most of the currently considered repositories will be reducing in nature, except for the repository in the US, which is going to be oxidizing. For the reducing repositories alloys such as carbon steel, stainless steels and titanium are being evaluated. For the repository in the US, some of the most corrosion resistant commercially available alloys are being investigated. This paper presents a summary of the behavior of the different materials under consideration for the repositories and the current understanding of the degradation modes of the proposed alloys in ground water environments from the point of view of general corrosion, localized corrosion and environmentally assisted cracking.

  1. KSC lubricant testing program. [lubrication characteristics and corrosion resistance

    NASA Technical Reports Server (NTRS)

    Lockhart, B. J.; Bryan, C. J.

    1973-01-01

    A program was conducted to evaluate the performance of various lubricants in use and considered for use at Kennedy Space Center (KSC). The overall objectives of the program were to: (1) determine the lubrication characteristics and relative corrosion resistance of lubricants in use and proposed for use at KSC; (2) identify materials which may be equivalent to or better than KELF-90 and Krytox 240 AC greases; and (3) identify or develop an improved lubricating oil suitable for use in liquid oxygen (LOX) pumps at KSC. It was concluded that: (1) earth gel thickened greases are very poor corrosion preventive materials in the KSC environment; (2) Halocarbon 25-5S and Braycote 656 were suitable substiutes for KELF-90 and Krytox 240 AC respectively; and (3) none of the oils evaluated possessed the necessary inertness, lubricity, and corrosion prevention characteristics for the KSC LOX pumping systems in their present configuration.

  2. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.

  3. Corrosion resistance investigation of vanadium alloys in liquid lithium

    NASA Astrophysics Data System (ADS)

    Borovitskaya, I. V.; Lyublinskiy, I. E.; Bondarenko, G. G.; Paramonova, V. V.; Korshunov, S. N.; Mansurova, A. N.; Lyakhovitskiy, M. M.; Zharkov, M. Yu.

    2016-12-01

    A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10-3 wt %) of vanadium and vanadium alloys (V-1.86Ga, V-3.4Ga-0.62Si, V-4.81Ti-4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 1022 m-2 at an irradiation temperature of 400°C. The degree of corrosion was estimated by measuring the changes in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.

  4. Influence of alloying elements on corrosion resistance of chromium--nickel steels in alkaline medium

    SciTech Connect

    Kanevskii, L.S.; Ebanoidze, D.D.; Kolesnikova, N.N.; Mosolov, A.V.; Shirokova, N.V.; Tovadze, F.N.

    1986-05-01

    The authors study the influence of nickel, chromium, and molybdenum on the behavior of chromium-nickel-molybdenum steels in concentrated alkali and alkali-chlorate solutions, simulating the media in partitioned alkali electrolysis evaporators. Defect-free forgings with no transcrystallization were obtained by pouring the steel into metal molds heated to 1400 degrees C. In the presence of molybdenum the passivation of the steels becomes more difficult, and as a result the corrosion potentials of certain steels in a chlorate-containing solution are much more negative than those of their molybdenum-free analogs.

  5. Centrifugally cast bimetallic pipe for offshore corrosion resistant pipelines

    SciTech Connect

    Yoshitake, A.; Torigoe, T.

    1994-12-31

    Centrifugally cast bimetallic pipes and fittings have been developed for the use of offshore oil and gas production. The metallurgical properties, mechanical properties, and corrosion properties of centrifugal a cast bimetallic pipe with outside metal of API 5L X52 to X65 internally clad with alloy 825 and 625 are discussed. First, molten steel for outer pipe is introduced into a rotating metallic mold. During the solidification of the outer pipe (carbon steel), the temperature of the pipe inside is monitored. After the solidification of the outer pipe, and when a certain temperature is reached, then a corrosion resistant alloy such as Alloy 825 or 625 for inside layer is poured. By controlling the casting conditions and selecting suitable flux, sound metallurgical bonded bimetallic pipe is produced with a minimum mixing layer at the interface also keeping a homogeneous outside wall thickness along the pipe length. The weld joints of the pipe are also evaluated from the view points of weldability, mechanical strength, fracture toughness, and corrosion resistance properties. The welding method applied was basically TIG welding (GTAW). COD tests at {minus}10 C are applied to the welds to investigate fracture toughness of the weld joints. Huey test according to ASTM A262C is carried out on the root of the welds as the corrosion test. As a result, the weld joint using filler wire of alloy625 from root to cover pass has proved a very reliable method from the point of view of mechanical and corrosion resistance properties. These centrifugally cast bimetallic pipes and fittings have been widely used for riser pipes, template process lines, top side and subsea manifolds, and flow bends for christmas trees in the North Sea.

  6. IMPROVED CORROSION RESISTANCE OF ALUMINA REFRACTORIES

    SciTech Connect

    John P. Hurley; Patty L. Kleven

    2001-09-30

    The initial objective of this project was to do a literature search to define the problems of refractory selection in the metals and glass industries. The problems fall into three categories: Economic--What do the major problems cost the industries financially? Operational--How do the major problems affect production efficiency and impact the environment? and Scientific--What are the chemical and physical mechanisms that cause the problems to occur? This report presents a summary of these problems. It was used to determine the areas in which the EERC can provide the most assistance through bench-scale and laboratory testing. The final objective of this project was to design and build a bench-scale high-temperature controlled atmosphere dynamic corrosion application furnace (CADCAF). The furnace will be used to evaluate refractory test samples in the presence of flowing corrodents for extended periods, to temperatures of 1600 C under controlled atmospheres. Corrodents will include molten slag, steel, and glass. This test should prove useful for the glass and steel industries when faced with the decision of choosing the best refractory for flowing corrodent conditions.

  7. Enhancement of Corrosion Resistance of Zinc Coatings Using Green Additives

    NASA Astrophysics Data System (ADS)

    Punith Kumar, M. K.; Srivastava, Chandan

    2014-10-01

    In the present work, morphology, microstructure, and electrochemical behavior of Zn coatings containing non-toxic additives have been investigated. Zn coatings were electrodeposited over mild steel substrates using Zn sulphate baths containing four different organic additives: sodium gluconate, dextrose, dextrin, and saccharin. All these additives are "green" and can be derived from food contents. Morphological and structural characterization using electron microscopy, x-ray diffraction, and texture co-efficient analysis revealed an appreciable alteration in the morphology and texture of the deposit depending on the type of additive used in the Zn plating bath. All the Zn coatings, however, were nano-crystalline irrespective of the type of additive used. Polarization and electrochemical impedance spectroscopic analysis, used to investigate the effect of the change in microstructure and morphology on corrosion resistance behavior, illustrated an improved corrosion resistance for Zn deposits obtained from plating bath containing additives as compared to the pure Zn coatings.

  8. DIFFUSION COATINGS FOR CORROSION RESISTANT COMPONENTS IN COAL GASIFICATION SYSTEMS

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Angel Sanjurjo

    2004-05-01

    Heat-exchangers, filters, turbines, and other components in integrated coal gasification combined cycle system must withstand demanding conditions of high temperatures and pressure differentials. Under the highly sulfiding conditions of the high temperature coal gas, the performance of components degrade significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy may improve is resistance to such sulfidation attack and decrease capital and operating costs. A review of the literature indicates that the corrosion reaction is the competition between oxidation and sulfidation reactions. The Fe- and Ni-based high-temperature alloys are susceptible to sulfidation attack unless they are fortified with high levels of Cr, Al, and Si. To impart corrosion resistance, these elements need not be in the bulk of the alloy and need only be present at the surface layers.

  9. Corrosion Resistant Steels for Structural Applications in Aircraft

    DTIC Science & Technology

    2007-11-02

    first structural stainless steel design are: A strong and tough fine lath martensite matrix; A stable passive oxide film on the material surface...for corrosion resistance; Nanoscale M2C dispersion strengthening through tempering while avoiding other carbides to improve strength and toughness...is all stainless steel , is prone to oxidation and decarburization if heat-treated in air. If sufficient stock is removed after heat-treatment, the

  10. Corrosion resistant coatings suitable for elevated temperature application

    DOEpatents

    Chan, Kwai S [San Antonio, TX; Cheruvu, Narayana Sastry [San Antonio, TX; Liang, Wuwei [Austin, TX

    2012-07-31

    The present invention relates to corrosion resistance coatings suitable for elevated temperature applications, which employ compositions of iron (Fe), chromium (Cr), nickel (Ni) and/or aluminum (Al). The compositions may be configured to regulate the diffusion of metals between a coating and a substrate, which may then influence coating performance, via the formation of an inter-diffusion barrier layer. The inter-diffusion barrier layer may comprise a face-centered cubic phase.

  11. Coatings for directional eutectics. [for corrosion and oxidation resistance

    NASA Technical Reports Server (NTRS)

    Felten, E. J.; Strangman, T. E.; Ulion, N. E.

    1974-01-01

    Eleven coating systems based on MCrAlY overlay and diffusion aluminide prototypes were evaluated to determine their capability for protecting the gamma/gamma prime-delta directionally solidified eutectic alloy (Ni-20Cb-6Cr-2.5Al) in gas turbine engine applications. Furnace oxidation and hot corrosion, Mach 0.37 burner-rig, tensile ductility, stress-rupture and thermomechanical fatigue tests were used to evaluate the coated gamma/gamma prime-delta alloy. The diffusion aluminide coatings provided adequate oxidation resistance at 1144 K (1600 F) but offered very limited protection in 114 K (1600 F) hot corrosion and 1366 K (2000 F) oxidation tests. A platinum modified NiCrAlY overlay coating exhibited excellent performance in oxidation testing and had no adverse effects upon the eutectic alloy.

  12. Corrosion resistance tests on NiTi shape memory alloy.

    PubMed

    Rondelli, G

    1996-10-01

    The corrosion performances of NiTi shape memory alloys (SMA) in human body simulating fluids were evaluated in comparison with other implant materials. As for the passivity current in potentiostatic conditions, taken as an index of ion release, the values are about three times higher for NiTi than for Ti6Al4V and austenitic stainless steels. Regarding the localized corrosion, while plain potentiodynamic scans indicated for NiTi alloy good resistance to pitting attack similar to Ti6Al4V, tests in which the passive film is abruptly damaged (i.e. potentiostatic scratch test and modified ASTM F746) pointed out that the characteristics of the passive film formed on NiTi alloy (whose strength can be related to the alloy's biocompatibility) are not as good as those on Ti6Al4V but are comparable or inferior to those on austenitic stainless steels.

  13. Chromate-free corrosion resistant conversion coatings for aluminum alloys

    SciTech Connect

    Buchheit, R.G.; Drewien, C.A.; Martinez, M.A.; Stoner, G.E.

    1995-03-01

    Inorganic polycrystalline hydrotalcite, Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O, coatings can be formed on aluminum and aluminum alloys by exposure to alkaline lithium carbonate solutions. This process is conducted using methods similar to traditional chromate conversion coating procedures, but does not use or produce toxic chemicals. The coating provides anodic protection and delays the onset of pitting during anodic polarization. Cathodic reactions are also inhibited which may also contribute to corrosion protection. Recent studies have shown that corrosion resistance can be increased by sealing hydrotalcite coated surfaces to transition metal salt solutions including Ce(NO{sub 3}){sub 3}, KMnO{sub 4} and Na{sub 2}MoO{sub 4}. Results from these studies are also reported.

  14. Corrosion-resistant Foamed Cements for Carbon Steels

    SciTech Connect

    Sugama T.; Gill, S.; Pyatina, T., Muraca, A.; Keese, R.; Khan, A.; Bour, D.

    2012-12-01

    The cementitious material consisting of Secar #80, Class F fly ash, and sodium silicate designed as an alternative thermal-shock resistant cement for the Enhanced Geothermal System (EGS) wells was treated with cocamidopropyl dimethylamine oxide-based compound as foaming agent (FA) to prepare numerous air bubble-dispersed low density cement slurries of and #61603;1.3 g/cm3. Then, the foamed slurry was modified with acrylic emulsion (AE) as corrosion inhibitor. We detailed the positive effects of the acrylic polymer (AP) in this emulsion on the five different properties of the foamed cement: 1) The hydrothermal stability of the AP in 200 and #61616;C-autoclaved cements; 2) the hydrolysis-hydration reactions of the slurry at 85 and #61616;C; 3) the composition of crystalline phases assembled and the microstructure developed in autoclaved cements; 4) the mechanical behaviors of the autoclaved cements; and, 5) the corrosion mitigation of carbon steel (CS) by the polymer. For the first property, the hydrothermal-catalyzed acid-base interactions between the AP and cement resulted in Ca-or Na-complexed carboxylate derivatives, which led to the improvement of thermal stability of the AP. This interaction also stimulated the cement hydration reactions, enhancing the total heat evolved during cement’s curing. Addition of AP did not alter any of the crystalline phase compositions responsible for the strength of the cement. Furthermore, the AP-modified cement developed the porous microstructure with numerous defect-free cavities of disconnected voids. These effects together contributed to the improvement of compressive-strength and –toughness of the cured cement. AP modification of the cement also offered an improved protection of CS against brine-caused corrosion. There were three major factors governing the corrosion protection: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS

  15. Monitoring ageing of alkali resistant glass fiber reinforced cement (GRC) using guided ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Eiras, J. N.; Amjad, U.; Mahmoudabadi, E.; Payá, J.; Bonilla, M.; Kundu, T.

    2013-04-01

    Glass fiber reinforced cement (GRC) is a Portland cement based composite with alkali resistant (AR) glass fibers. The main drawback of this material is the ageing of the reinforcing fibers with time and especially in presence of humidity in the environment. Until now only destructive methods have been used to evaluate the durability of GRC. In this study ultrasonic guided wave inspection of plate shaped specimens has been carried out. The results obtained here show that acoustic signatures are capable of discerning ageing in GRC. Therefore, the ultrasonic guided wave based inspection technique is a promising method for the nondestructive evaluation of the durability of the GRC.

  16. Characteristic corrosion resistance of nanocrystalline TiN films prepared by high density plasma reactive magnetron sputtering.

    PubMed

    Kim, J H; Kang, C G; Kim, Y T; Cheong, W S; Song, P K

    2013-07-01

    Nanocytalline TiN films were deposited on non-alkali glass and Al substrates by reactive DC magnetron sputtering (DCMS) with an electromagnetic field system (EMF). The microstructure and corrosion resistance of the TiN-coated Al substrates were estimated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. All the TiN films shows that they have a (111) preferred orientation at room temperature. TiN films deposited on Al substrate using only DCMS 400 W showed a sheet resistance of 3.22 x 10-1 omega/symbol see texts (resistivity, 3.22 x 10-5 omegacm). On the other hand, a relatively low sheet resistance of 1.91 x 10-1 omega/symbol see text (1.91 x 10-5 omegacm) was obtained for the dense nanocrystalline TiN film deposited on Al substrate using DCMS 375 W+ EMF 25 W, indicating that the introduction of an EMF system enhanced the electrical properties of the TiN film. TiN films deposited on Al substrate at 400 degreesC had a (200) preferred orientation with the lowest sheet resistance of 1.28x10-1 omega/symbol see texts (1.28 x 10-5 omegacm) which was attributed to reduced nano size defects and an improvement of the crystallinity. Potentiostatic and Potentiodynamic tests with a TiN-coated Al showed good corrosion resistance (l/corr, = 2.03 microA/cm2, Ecorr = -348 mV) compared to the uncoated Al substrate (/corr = 4.45 microA/cm2, Ecorr = -650 mV). Furthermore, EMF system showed that corrosion resistance of the TiN film also was enhanced compared to DCMS only. For the TiN film deposited on Al substrate at 400 degreesC, corrosion current and potential was 0.63 micro/cm2 and -1.5 mV, respectively. This improved corrosion resistance of the TiN film could be attributed to the densification of the film caused by enhancement of nitrification with increasing high reactive nitrogen radicals.

  17. Corrosion

    ERIC Educational Resources Information Center

    Slabaugh, W. H.

    1974-01-01

    Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

  18. Improvement of the linear polarization resistance method for testing steel corrosion inhibitors

    NASA Astrophysics Data System (ADS)

    Faritov, A. T.; Rozhdestvenskii, Yu. G.; Yamshchikova, S. A.; Minnikhanova, E. R.; Tyusenkov, A. S.

    2016-11-01

    The linear polarization resistance method is used to improve the technique of corrosion control in liquid conducting according to GOST 9.514-99 (General Corrosion and Aging Protection System. Corrosion Inhibitors for Metals in Water Systems. Electrochemical Method of Determining the Protective Ability). Corrosion monitoring is shown to be performed by electronic devices with real-time data transfer to industrial controllers and SCADA systems.

  19. Method for inhibiting corrosion of nickel-containing alloys

    DOEpatents

    DeVan, J.H.; Selle, J.E.

    Nickel-containing alloys are protected against corrosion by contacting the alloy with a molten alkali metal having dissolved therein aluminum, silicon or manganese to cause the formation of a corrosion-resistant intermetallic layer. Components can be protected by applying the coating after an apparatus is assembled.

  20. Improved fracture toughness corrosion-resistant bearing material

    NASA Technical Reports Server (NTRS)

    Bamberger, E. N.; Nahm, A. H.

    1986-01-01

    A development program was performed to establish whether a corrosion-resistant bearing material, such as a 14Cr steel, could be modified to allow carburization, thereby providing the excellent fracture toughness characteristics feasible with this process. The alloy selected for investigation was AMS 5749. Several modifications were made including the addition of a small amount of nickel for austenite stabilization. While some promising results were achieved, the primary objective of an acceptable combination of case hardness and microstructure was not attained. Because the high chromium content presents a serious problem in achieving a viable carburizing cycle, a number of experimental steels having lower chromium contents (8 to 12%) were produced in laboratory quantities and evaluated. The results were basically the same as those initially obtained with the modified AMS 5749. Corrosion tests were performed on AMS 5749, AISI M50, and 52100 bearing steels as well as some of the lower chromium steels. These tests showed that a reduced chromium level (10 to 12%) provided essentially the same corrosion protection as the 14Cr steels.

  1. Development of weldable, corrosion-resistant iron-aluminide alloys

    SciTech Connect

    Maziasz, P.J.; Goodwin, G.M.; Wang, X.L.

    1995-05-01

    Corrosion-resistant, weldable FeAl alloys have been developed with improved high-temperature strength industrial applications. Previous processing difficulties with these alloys led to their evaluation as weld-overlay claddings on conventional structural steels to take advantage of their good properties now. Simplified and better processing methods for monolithic FeAl components are also currently being developed so that components for industrial testing can be made. Other avenues for producing FeAl coatings are currently being explored. Neutron scattering experiments residual stress distributions in the FeAl weld-overlay cladding began in FY 1993 and continued this year.

  2. Corrosion resistance of premodeled wires made of stainless steel used for heart electrotherapy leaders

    NASA Astrophysics Data System (ADS)

    Przondziono, J.; Walke, W.; Młynarski, R.; Szatka, W.

    2012-05-01

    The purpose of the study is to evaluate resistance to electrochemical corrosion of wire made of X10CrNi18-8 stainless steel designed for use in cardiology treatment. The influence of strain formed in the premodeling process and methods of wire surface preparation to corrosive resistance in artificial plasma solution were analysed. Wire corrosion tests were carried out in the solution of artificial plasma. Resistance to electrochemical corrosion was evaluated on the ground of recorded curves of anodic polarization by means of potentiodynamic method. Potentiodynamic tests carried out enabled to determine how the resistance to pitting corrosion of wire changes, depending on strain formed in the premodeling process as well as on the method of wire surface preparation. For evaluation of phenomena occurring on the surface of tested steel, electrochemical impedance spectroscopy (EIS) was applied. Deterioration of corrosive properties of wire along with the increase in the formed strain hardening was observed.

  3. Evaluation of the corrosion resistance of Fe-Al-Cr alloys in simulated low NOx environments

    SciTech Connect

    Deacon, R.M.; DuPont, J.N.; Kiely, C.J.; Marder, A.R.; Tortorelli, P.F.

    2009-08-15

    Due to their excellent corrosion resistance, iron aluminum alloys are currently being considered for use as weld claddings in fossil fuel fired power plants. The susceptibility to hydrogen cracking of these alloys at higher aluminum concentrations has led researchers to examine the effect of chromium additions on the corrosion resistance of lower aluminum alloys. In this work, three iron aluminum alloys were exposed to simulated coal combustion environments at 500 and 700{sup o}C for short (100 h) and long (5000 h) isothermal durations. Scanning electron microscopy was used to analyze the corrosion products. All alloys exhibited excellent corrosion resistance during short term exposures. For longer test times, increasing the aluminum concentration improved alloy corrosion resistance. The addition of chromium to the binary iron aluminum alloy prevented the formation iron sulfide and resulted in slower corrosion kinetics. A general classification of the scales developed on these alloys is presented.

  4. Characterization of the corrosion resistance of biologically active solutions: The effects of anodizing and welding

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.

    1991-01-01

    An understanding of fabrication processes, metallurgy, electrochemistry, and microbiology is crucial to the resolution of microbiologically influenced corrosion (MIC) problems. The object of this effort was to use AC impedance spectroscopy to characterize the corrosion resistance of Type II anodized aluminum alloy 2219-T87 in sterile and biologically active media and to examine the corrosion resistance of 316L, alloy 2219-T87, and titanium alloy 6-4 in the welded and unwelded conditions. The latter materials were immersed in sterile and biologically active media and corrosion currents were measured using the polarization resistance (DC) technique.

  5. Corrosion resistance of titanium ion implanted AZ91 magnesium alloy

    SciTech Connect

    Liu Chenglong; Xin Yunchang; Tian Xiubo; Zhao, J.; Chu, Paul K.

    2007-03-15

    Degradable metal alloys constitute a new class of materials for load-bearing biomedical implants. Owing to their good mechanical properties and biocompatibility, magnesium alloys are promising in degradable prosthetic implants. The objective of this study is to improve the corrosion behavior of surgical AZ91 magnesium alloy by titanium ion implantation. The surface characteristics of the ion implanted layer in the magnesium alloys are examined. The authors' results disclose that an intermixed layer is produced and the surface oxidized films are mainly composed of titanium oxide with a lesser amount of magnesium oxide. X-ray photoelectron spectroscopy reveals that the oxide has three layers. The outer layer which is 10 nm thick is mainly composed of MgO and TiO{sub 2} with some Mg(OH){sub 2}. The middle layer that is 50 nm thick comprises predominantly TiO{sub 2} and MgO with minor contributions from MgAl{sub 2}O{sub 4} and TiO. The third layer from the surface is rich in metallic Mg, Ti, Al, and Ti{sub 3}Al. The effects of Ti ion implantation on the corrosion resistance and electrochemical behavior of the magnesium alloys are investigated in simulated body fluids at 37{+-}1 deg. C using electrochemical impedance spectroscopy and open circuit potential techniques. Compared to the unimplanted AZ91 alloy, titanium ion implantation significantly shifts the open circuit potential (OCP) to a more positive potential and improves the corrosion resistance at OCP. This phenomenon can be ascribed to the more compact surface oxide film, enhanced reoxidation on the implanted surface, as well as the increased {beta}-Mg{sub 12}Al{sub 17} phase.

  6. Surface modification to improve fireside corrosion resistance of Fe-Cr ferritic steels

    DOEpatents

    Park, Jong-Hee; Natesan, Krishnamurti; Rink, David L.

    2010-03-16

    An article of manufacture and a method for providing an Fe--Cr ferritic steel article of manufacture having a surface layer modification for corrosion resistance. Fe--Cr ferritic steels can be modified to enhance their corrosion resistance to liquid coal ash and other chemical environments, which have chlorides or sulfates containing active species. The steel is modified to form an aluminide/silicide passivating layer to reduce such corrosion.

  7. Fabrication and corrosion resistance of superhydrophobic magnesium alloy

    NASA Astrophysics Data System (ADS)

    Feng, Libang; Zhu, Yali; Fan, Weibo; Wang, Yanping; Qiang, Xiaohu; Liu, Yanhua

    2015-08-01

    A superhydrophobic magnesium alloy (AZ91) is successfully fabricated by sulfuric acid etching, AgNO3 treatment, and dodecyl mercaptan (DM) modification. The effect of the fabrication procedure, the concentration and treatment time of sulfuric acid, AgNO3, and DM on morphology, phase structure, surface wettability, and surface composition of the AZ91 is investigated in detail. Consequently, the optimal treatment parameters are selected, and the superhydrophobic magnesium alloy with a water contact angle of 154° and a sliding angle of 5° is fabricated. The acid etching endows the AZ91 surface with rough structure while the AgNO3 treatment results in more protrusions and grooves. Meanwhile, the long hydrophobic alkyl chains are self-assembled onto the rough AZ91 surface upon DM modification. As a result, the multilayer of netlike surface with protrusions and grooves together with the coral-like structure is obtained. Additionally, the magnesium alloy with higher water contact angle has better corrosion resistance, while the magnesium alloy with the superhydrophobic property has the best corrosion resistance.

  8. Effect of sorbed molecules on the resistivity of alkali metal-graphite intercalation compounds

    SciTech Connect

    Akuzawa, Noboru Kunihashi, Yoji; Sato, Yuki; Tsuchiya, Ken-ichi; Matsumoto, Rika

    2007-03-15

    Alkali metal-graphite intercalation compounds with the composition of MC{sub 24} (M=K, Rb, Cs) were prepared by heating a mixture of MC{sub 8} (saturated compound) and graphite sheet (Grafoil) at 350-450 deg. C. The resistivity perpendicular to the layer planes ({rho} {sub c}) of the resulting compounds was determined by the two-terminal method. The anisotropy factor of the resistivity, ({rho} {sub c}/{rho} {sub a}), of KC{sub 24} prepared from Grafoil was {approx}130, being about 1/6-1/10 in magnitude compared with that of KC{sub 24} prepared from highly oriented pyrolytic graphite. The resistivity change during sorption of hydrogen (at 90 K), ethylene (at 194 K) and acetylene (at 194 K) was determined. The resistivity of MC{sub 24} increased with increase of the sorbed amount of H{sub 2}. The magnitude of the increase was in the order KC{sub 24}>RbC{sub 24}>CsC{sub 24}. This resistivity increase was considered to be due to the expansion along c-direction which reduces the charge-transfer interaction between the carbon layers and potassium ions, resulting in the decrease of the density of the conduction electron. The resistivity of MC{sub 24} increased extensively during sorption of C{sub 2}H{sub 4} and C{sub 2}H{sub 2}. It was discussed in connection with the in-plane structural transition and chemical interaction between alkali metal ions and sorbed molecules. - Graphical abstract: The resistivity of MC{sub 24} increased with increase of the sorbed amount of H{sub 2}. The magnitude of the increase was in the order KC{sub 24}>RbC{sub 24}>CsC{sub 24}. This resistivity increase was considered to be due to the expansion along c-direction which reduces the charge-transfer interaction between the carbon layers and potassium ions.

  9. Structural factors governing steel resistance during operation in corrosive media under cavitation conditions

    SciTech Connect

    Berezovskaya, V.V.

    1988-05-01

    To evaluate the effect of structural factors on the corrosion resistance of steel under cavitation, a study was made of the effect of cavitation on chromium (95Kh18) and chromium-nickel (12Kh18N9T) corrosion-resistant steels and also on maraging steel 03Kh10N5K5M3KTYuS, specially developed for the loading conditions being studied, together with the austenitic steel 03Kh23N28M3D3T. A study of the effect of martensite content on corrosion and cavitation-corrosion resistance was carried out on steels 12Kh18N9T and 95Kh18 after different treatments. Corrosion tests were conducted in solutions of H/sub 2/SO/sub 4/ and H/sub 3/PO/sub 4/ and scanning electron microscopy was used to assess phase and corrosion behavior. Maraging steels treated for maximum hardness and overaging exhibited high cavitation-corrosion resistance in acid solutions owing to high strength and resistance to microcrack initiation and propagation. It was recommended that under cavitation conditions in corrosive media, high alloy austenitic corrosion-resistant steels are substituted by maraging steels.

  10. The resistance of high frequency inductive welded pipe to grooving corrosion in salt water

    SciTech Connect

    Duran, C.; Triess, E.; Herbsleb, G.

    1986-09-01

    When exposed to neutral, salt-containing waters, electric resistant welded pipe in carbon and low alloy steels with increased sulfur contents may suffer preferential corrosion attack in the weld area. Because of its appearance, this type of corrosion is called grooving corrosion. The susceptibility to grooving corrosion may be determined and quantitatively described by means of an accelerated potentiostatic exposure test. The importance of type, concentration, and temperature of the electrolytic solution; potential; test duration; and the sulfur content of the steel in the accelerated corrosion test and the susceptibility of steels to grooving corrosion are described. Line pipe in high frequency inductive (HFI) welded carbon and low alloy steels are resistant to grooving corrosion particularly because of their low sulfur content.

  11. Field trials for corrosion inhibitor selection and optimization, using a new generation of electrical resistance probes

    SciTech Connect

    Ridd, B.; Blakset, T.J.; Queen, D.

    1998-12-31

    Even with today`s availability of corrosion resistant alloys, carbon steels protected by corrosion inhibitors still dominate the material selection for pipework in the oil and gas production. Even though laboratory screening tests of corrosion inhibitor performance provides valuable data, the real performance of the chemical can only be studied through field trials which provide the ultimate test to evaluate the effectiveness of an inhibitor under actual operating conditions. A new generation of electrical resistance probe has been developed, allowing highly sensitive and immediate response to changes in corrosion rates on the internal environment of production pipework. Because of the high sensitivity, the probe responds to small changes in the corrosion rate, and it provides the corrosion engineer with a highly effective method of optimizing the use of inhibitor chemicals resulting in confidence in corrosion control and minimizing detrimental environmental effects.

  12. Electrochemical and pitting corrosion resistance of AISI 4145 steel subjected to massive laser shock peening treatment with different coverage layers

    NASA Astrophysics Data System (ADS)

    Lu, J. Z.; Han, B.; Cui, C. Y.; Li, C. J.; Luo, K. Y.

    2017-02-01

    The effects of massive laser shock peening (LSP) treatment with different coverage layers on residual stress, pitting morphologies in a standard corrosive solution and electrochemical corrosion resistance of AISI 4145 steel were investigated by pitting corrosion test, potentiodynamic polarisation test, and SEM observations. Results showed massive LSP treatment can effectively cause an obvious improvement of pitting corrosion resistance of AISI 4145 steel, and increased coverage layer can also gradually improve its corrosion resistance. Massive LSP treatment with multiple layers was shown to influence pitting corrosion behaviour in a standard corrosive solution.

  13. Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique

    PubMed Central

    Xu, Yunze; Li, Kaiqiang; Liu, Liang; Yang, Lujia; Wang, Xiaona; Huang, Yi

    2016-01-01

    In this paper, a new kind of carbon steel (CS) and stainless steel (SS) galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER) method and zero resistance ammeter (ZRA) technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR) and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH)2 solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete. PMID:27618054

  14. Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique.

    PubMed

    Xu, Yunze; Li, Kaiqiang; Liu, Liang; Yang, Lujia; Wang, Xiaona; Huang, Yi

    2016-09-08

    In this paper, a new kind of carbon steel (CS) and stainless steel (SS) galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER) method and zero resistance ammeter (ZRA) technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR) and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH)₂ solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete.

  15. Comparative Stress Corrosion Cracking and General Corrosion Resistance of Annealed and Hardened 440 C Stainless Steel - New Techniques in Stress Corrosion Testing

    NASA Technical Reports Server (NTRS)

    Mendreck, M. J.; Hurless, B. E.; Torres, P. D.; Danford, M. D.

    1998-01-01

    The corrosion and stress corrosion cracking (SCC) characteristics of annealed and hardened 440C stainless steel were evaluated in high humidity and 3.5-percent NaCl solution. Corrosion testing consisted of an evaluation of flat plates, with and without grease, in high humidity, as well as electrochemical testing in 3.5-percent NaCl. Stress corrosion testing consisted of conventional, constant strain, smooth bar testing in high humidity in addition to two relatively new techniques under evaluation at MSFC. These techniques involve either incremental or constant rate increases in the load applied to a precracked SE(B) specimen, monitoring the crack-opening-displacement response for indications of crack growth. The electrochemical corrosion testing demonstrated an order of magnitude greater general corrosion rate in the annealed 440C. All techniques for stress corrosion testing showed substantially better SCC resistance in the annealed material. The efficacy of the new techniques for stress corrosion testing was demonstrated both by the savings in time and the ability to better quantify SCC data.

  16. Effect of Welding Heat Input on the Corrosion Resistance of Carbon Steel Weld Metal

    NASA Astrophysics Data System (ADS)

    Lu, Yongxin; Jing, Hongyang; Han, Yongdian; Xu, Lianyong

    2016-02-01

    The corrosion resistance of carbon steel weld metal with three different microstructures has been systematically evaluated using electrochemical techniques with the simulated produced water containing CO2 at 90 °C. Microstructures include acicular ferrite, polygonal ferrite, and a small amount of pearlite. With welding heat input increasing, weld metal microstructure becomes more uniform. Electrochemical techniques including potentiodynamic polarization curve, linear polarization resistance, and electrochemical impedance spectroscopy were utilized to characterize the corrosion properties on weld joint, indicating that the best corrosion resistance corresponded to the weld metal with a polygonal ferrite microstructure, whereas the weld metal with the acicular ferrite + polygonal ferrite microstructure showed the worst corrosion resistance. The samples with high welding heat input possessed better corrosion resistance. Results were discussed in terms of crystal plane orientation, grain size, and grain boundary type found in each weld metal by electron backscatter diffraction test.

  17. A high-specific-strength and corrosion-resistant magnesium alloy.

    PubMed

    Xu, Wanqiang; Birbilis, Nick; Sha, Gang; Wang, Yu; Daniels, John E; Xiao, Yang; Ferry, Michael

    2015-12-01

    Ultra-lightweight alloys with high strength, ductility and corrosion resistance are desirable for applications in the automotive, aerospace, defence, biomedical, sporting and electronic goods sectors. Ductility and corrosion resistance are generally inversely correlated with strength, making it difficult to optimize all three simultaneously. Here we design an ultralow density (1.4 g cm(-3)) Mg-Li-based alloy that is strong, ductile, and more corrosion resistant than Mg-based alloys reported so far. The alloy is Li-rich and a solute nanostructure within a body-centred cubic matrix is achieved by a series of extrusion, heat-treatment and rolling processes. Corrosion resistance from the environment is believed to occur by a uniform lithium carbonate film in which surface coverage is much greater than in traditional hexagonal close-packed Mg-based alloys, explaining the superior corrosion resistance of the alloy.

  18. A high-specific-strength and corrosion-resistant magnesium alloy

    NASA Astrophysics Data System (ADS)

    Xu, Wanqiang; Birbilis, Nick; Sha, Gang; Wang, Yu; Daniels, John E.; Xiao, Yang; Ferry, Michael

    2015-12-01

    Ultra-lightweight alloys with high strength, ductility and corrosion resistance are desirable for applications in the automotive, aerospace, defence, biomedical, sporting and electronic goods sectors. Ductility and corrosion resistance are generally inversely correlated with strength, making it difficult to optimize all three simultaneously. Here we design an ultralow density (1.4 g cm-3) Mg-Li-based alloy that is strong, ductile, and more corrosion resistant than Mg-based alloys reported so far. The alloy is Li-rich and a solute nanostructure within a body-centred cubic matrix is achieved by a series of extrusion, heat-treatment and rolling processes. Corrosion resistance from the environment is believed to occur by a uniform lithium carbonate film in which surface coverage is much greater than in traditional hexagonal close-packed Mg-based alloys, explaining the superior corrosion resistance of the alloy.

  19. Effect of High Temperature Aging on the Corrosion Resistance of Iron Based Amorphous Alloys

    SciTech Connect

    Day, S D; Haslam, J J; Farmer, J C; Rebak, R B

    2007-08-10

    Iron-based amorphous alloys can be more resistant to corrosion than polycrystalline materials of similar compositions. However, when the amorphous alloys are exposed to high temperatures they may recrystallize (or devitrify) thus losing their resistance to corrosion. Four different types of amorphous alloys melt spun ribbon specimens were exposed to several temperatures for short periods of time. The resulting corrosion resistance was evaluated in seawater at 90 C and compared with the as-prepared ribbons. Results show that the amorphous alloys can be exposed to 600 C for 1-hr. without losing the corrosion resistance; however, when the ribbons were exposed at 800 C for 1-hr. their localized corrosion resistance decreased significantly.

  20. 77 FR 301 - Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea: Institution of Five-Year...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-04

    ... COMMISSION Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea: Institution of Five-Year Reviews Concerning the Countervailing Duty Order on Corrosion-Resistant Carbon Steel Flat Products From Korea and the Antidumping Duty Orders on Corrosion-Resistant Carbon Steel Flat Products From Germany...

  1. 78 FR 59652 - Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-27

    ... International Trade Administration Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic of... administrative review of the antidumping duty order on certain corrosion-resistant carbon steel flat products... Results. \\2\\ See Certain Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea:...

  2. 77 FR 27438 - Certain Corrosion-Resistant Carbon Steel Flat Products From Korea: Final Results of Expedited...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-10

    ... International Trade Administration Certain Corrosion-Resistant Carbon Steel Flat Products From Korea: Final... third five-year sunset review of the countervailing duty order on certain corrosion-resistant carbon..., plated, or coated with corrosion-resistant metals such as zinc, aluminum, or zinc-, aluminum-, nickel-...

  3. 78 FR 16247 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea; Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-14

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea... antidumping duty order on corrosion-resistant carbon steel flat products (CORE) from the Republic of Korea... section entitled ``Final Results of Review.'' \\1\\ See Certain Corrosion-Resistant Carbon Steel...

  4. 77 FR 44213 - Corrosion-Resistant Carbon Steel Flat Products From Germany and the Republic of Korea...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-27

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From Germany and the Republic... certain corrosion-resistant carbon steel flat products (``CORE'') from Germany and the Republic of Korea..., Director, Office 3, on ``Sunset Reviews of the Antidumping Duty Orders on Corrosion-Resistant Carbon...

  5. 76 FR 77775 - Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea... countervailing duty order on corrosion-resistant carbon steel flat products from the Republic of Korea covering the period January 1, 2009, through December 31, 2009. See Corrosion-Resistant Carbon Steel...

  6. 77 FR 24221 - Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Notice of Commission...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-23

    ... COMMISSION Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Notice of Commission... countervailing duty order on corrosion-resistant carbon steel flat products from Korea and the antidumping duty orders on corrosion- resistant carbon steel flat products from Germany and Korea would be likely to...

  7. 77 FR 13093 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea... administrative review of the countervailing duty (``CVD'') order on corrosion-resistant carbon steel flat... Review'' below. \\1\\ See Corrosion-Resistant Carbon Steel Flat Products from the Republic of...

  8. 78 FR 59651 - Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-27

    ... International Trade Administration Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic of... fourteenth administrative review of the antidumping duty order on certain corrosion-resistant carbon steel... aspects of the Final Results. \\2\\ See Certain Corrosion-Resistant Carbon Steel Flat Products from...

  9. 77 FR 31877 - Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Scheduling of Full Five...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-30

    ... COMMISSION Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Scheduling of Full Five... duty order on corrosion-resistant carbon steel flat products from Korea and the antidumping duty orders on corrosion- resistant carbon steel flat products from Germany and Korea would be likely to lead...

  10. 78 FR 16832 - Corrosion-Resistant Carbon Steel Flat Products From Germany and the Republic of Korea: Revocation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-19

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From Germany and the Republic... corrosion-resistant carbon steel flat products (``CORE'') from Germany and the Republic of Korea (``Korea...-Year (``Sunset'') Review, 77 FR 85 (January 3, 2012). \\2\\ See Corrosion-Resistant Carbon Steel...

  11. 78 FR 19210 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...) has completed its administrative review of the countervailing duty (CVD) order on corrosion-resistant...\\ See Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results...

  12. Corrosion Resistant Cladding by YAG Laser Welding in Underwater Environment

    SciTech Connect

    Tsutomi Kochi; Toshio Kojima; Suemi Hirata; Ichiro Morita; Katsura Ohwaki

    2002-07-01

    It is known that stress-corrosion cracking (SCC) will occur in nickel-base alloys used in Reactor Pressure Vessel (RPV) and Internals of nuclear power plants. A SCC sensitivity has been evaluated by IHI in each part of RPV and Internals. There are several water level instrumentation nozzles installed in domestic BWR RPV. In water level instrumentation nozzles, 182 type nickel-base alloys were used for the welding joint to RPV. It is estimated the SCC potential is high in this joint because of a higher residual stress than the yield strength (about 400 MPa). This report will describe a preventive maintenance method to these nozzles Heat Affected Zone (HAZ) and welds by a corrosion resistant cladding (CRC) by YAG Laser in underwater environment (without draining a reactor water). There are many kinds of countermeasures for SCC, for example, Induction Heating Stress Improvement (IHSI), Mechanical Stress Improvement Process (MSIP) and so on. A YAG laser CRC is one of them. In this technology a laser beam is used for heat source and irradiated through an optical fiber to a base metal and SCC resistant material is used for welding wires. After cladding the HAZ and welds are coated by the corrosion resistant materials so their surfaces are improved. A CRC by gas tungsten arc welding (GTAW) in an air environment had been developed and already applied to a couple of operating plants (16 Nozzles). This method was of course good but it spent much time to perform because of an installation of some water-proof working boxes to make a TIG-weldability environment. CRC by YAG laser welding in underwater environment has superior features comparing to this conventional TIG method as follows. At the viewpoint of underwater environment, (1) an outage term reduction (no drainage water). (2) a radioactive exposure dose reduction for personnel. At that of YAG laser welding, (1) A narrower HAZ. (2) A smaller distortion. (3) A few cladding layers. A YAG laser CRC test in underwater

  13. Assessment of corrosion resistance of Nd-Fe-B magnets by silanization for orthodontic applications

    NASA Astrophysics Data System (ADS)

    Fabiano, F.; Celegato, F.; Giordano, A.; Borsellino, C.; Bonaccorsi, L.; Calabrese, L.; Tiberto, P.; Cordasco, G.; Matarese, G.; Fabiano, V.; Azzerboni, B.

    2014-02-01

    Nd-Fe-B permanent magnets are characterised by excellent magnetic properties. However, being extremely vulnerable to the attack of both climate and corrosive environments, their applications are limited. This paper describes how, at different thicknesses of N-propyl-trimetoxy-silane, the coating affects the magnetic force of nickel plated magnets. We also investigate if the corrosion resistance of silanized Nd-Fe-B magnets increases in mildly corrosive environments by immersing them in a synthetic saliva solution. It was found that the silanization treatment does not affect the strength of the magnetic force and provide an enhancement of the corrosion resistance of the substrate.

  14. Corrosion resistance of Ti-Ta-Zr coatings in the Boiling Acid Solutions

    NASA Astrophysics Data System (ADS)

    Polyakov, I. A.; Lenivtseva, O. G.; Samoylenko, V. V.; Colkovski, M. G.; Ivanchik, I. S.

    2016-11-01

    In this study corrosion resistance of Ti-Ta-Zr coatings fabricated on VT14 titanium alloy workpieces using a high-energy electron beam injected in the atmosphere was investigated. Estimation of corrosion resistance of surface alloyed layers was carried out by the weight-change method. Boiling solution of 65 % nitric acid in water and 5 % of sulfuric acid in water were used as the corrosive environments. Investigation of samples after corrosion tests was carried out using a Carl Zeiss EVO 50 XVP scanning electron microscope.

  15. Water-Repellent Thin Film with High Alkali Resistance Using the Sol-Gel Method for Ink Jet Printer Head

    NASA Astrophysics Data System (ADS)

    Nakagawa, Tohru; Hiwatashi, Tatsuya

    2002-06-01

    Water-repellent thin films from silane coupling agents have been widely used for inducing hydrophobicity on various surfaces. However, films obtained by conventional methods have poor durability against alkaline solutions. A new water-repellent thin film with high alkali resistance has been obtained for the first time by the sol-gel method using fluoroalkylmethoxysilane and 1,4-bis(trimethoxysilylethyl)benzene (BTB). The film maintained its hydrophobicity after soaking in alkaline ink with \\mathit{pH}=8.9 at 70°C for 500 h. While the film maintained alkali resistance after being heat-treated at temperatures up to 300°C, that heat-treated at 400°C lost its alkali resistance. Fourier transform infrared measurements of the film indicated that ethyl groups in BTB molecules burn or oxidize at 400°C. It is speculated that the ethyl groups in the vicinity of siloxane bonds and the three-dimensional BTB polymer network prevent OH-ions from approaching and breaking the siloxane bonds in the film, and thus the film has high alkali resistance. We demonstrate that the new water-repellent film is applicable to the ink jet printer head.

  16. Structural strength of welded shells made of corrosion-resistant maraging steels

    SciTech Connect

    Raimond, E.D.; Lapin, P.G.; Pautkin, U.S.; Shiganov, N.V.; Tashchikov, V.S.

    1986-03-01

    The authors devise special measures to increase the resistance of welded shells made of corrosion-resistant maraging steels. High structural strenght is ensured for shells loaded by internal pressure when ait (impact toughness) greater than or equal to10 J/cm/sup 2/. For welds of corrosion-resistant maraging steels of the O3Kh11N10M2T type, this condition is satisfied when the weld strength does not exceed 1400-1450 MPa. A structural strength of 15001750 MPa in welds of corrosion-resistant maraging steels can be obtained by means of mechanicothermal treatment.

  17. Corrosion resistance of biodegradable Mg with a composite polymer coating.

    PubMed

    Chen, Peng; Sun, Jiadi; Zhu, Ye; Yu, Xun; Meng, Long; Li, Yang; Liu, Xiaoya

    2016-12-01

    Degrading Mg and its alloys are a category of implant materials for bone surgery, but rapid corrosion in physiological environment limits their clinical applications. To improve the corrosion resistance of Mg-based implants, a biodegradable composite polymer coating is deposited on an Mg rod in this work. The strategy is to decorate Mg surfaces with poly(γ-glutamic acid)-g-7-amino-4-methylcoumarin/hydroxyapatite (γ-PGA-g-AMC/HAp) composite nanoparticles through electrophoretic deposition in ethanol. The morphology and chemical composition of the resulting coating material are determined by scanning electron microscopy and Fourier transform infrared spectroscopy. Sample rods of bare Mg and coated Mg are implanted intramedullary into the femora of New Zealand white rabbits, periodic radiography and post-autopsy histopathology of each sample are analyzed. The obtained in vivo results clearly confirm that the coating material decreases degradation rate of the underlying Mg sample and appears good histocompatibility and osteoinductivity. The main aim of this work is to investigate the degradation process of bare Mg and coated Mg samples in bone environment and their effect on the surrounding bone tissue.

  18. Is cell viability always directly related to corrosion resistance of stainless steels?

    PubMed

    Salahinejad, E; Ghaffari, M; Vashaee, D; Tayebi, L

    2016-05-01

    It has been frequently reported that cell viability on stainless steels is improved by increasing their corrosion resistance. The question that arises is whether human cell viability is always directly related to corrosion resistance in these biostable alloys. In this work, the microstructure and in vitro corrosion behavior of a new class of medical-grade stainless steels were correlated with adult human mesenchymal stem cell viability. The samples were produced by a powder metallurgy route, consisting of mechanical alloying and liquid-phase sintering with a sintering aid of a eutectic Mn-Si alloy at 1050 °C for 30 and 60 min, leading to nanostructures. In accordance with transmission electron microscopic studies, the additive particles for the sintering time of 30 min were not completely melted. Electrochemical impedance spectroscopic experiments suggested the higher corrosion resistance for the sample sintered for 60 min; however, a better cell viability on the surface of the less corrosion-resistant sample was unexpectedly found. This behavior is explained by considering the higher ion release rate of the Mn-Si additive material, as preferred sites to corrosion attack based on scanning electron microscopic observations, which is advantageous to the cells in vitro. In conclusion, cell viability is not always directly related to corrosion resistance in stainless steels. Typically, the introduction of biodegradable and biocompatible phases to biostable alloys, which are conventionally anticipated to be corrosion-resistant, can be advantageous to human cell responses similar to biodegradable metals.

  19. Environmental Cracking of Corrosion Resistant Alloys in the Chemical Process Industry - A Review

    SciTech Connect

    Rebak, R B

    2006-12-04

    A large variety of corrosion resistant alloys are used regularly in the chemical process industry (CPI). The most common family of alloys include the iron (Fe)-based stainless steels, nickel (Ni) alloys and titanium (Ti) alloys. There also other corrosion resistant alloys but their family of alloys is not as large as for the three groups mentioned above. All ranges of corrosive environments can be found in the CPI, from caustic solutions to hot acidic environments, from highly reducing to highly oxidizing. Stainless steels are ubiquitous since numerous types of stainless steels exist, each type tailored for specific applications. In general, stainless steels suffer stress corrosion cracking (SCC) in hot chloride environments while high Ni alloys are practically immune to this type of attack. High nickel alloys are also resistant to caustic cracking. Ti alloys find application in highly oxidizing solutions. Solutions containing fluoride ions, especially acid, seem to be aggressive to almost all corrosion resistant alloys.

  20. Thermally oxidized titania nanotubes enhance the corrosion resistance of Ti6Al4V.

    PubMed

    Grotberg, John; Hamlekhan, Azhang; Butt, Arman; Patel, Sweetu; Royhman, Dmitry; Shokuhfar, Tolou; Sukotjo, Cortino; Takoudis, Christos; Mathew, Mathew T

    2016-02-01

    The negative impact of in vivo corrosion of metallic biomedical implants remains a complex problem in the medical field. We aimed to determine the effects of electrochemical anodization (60V, 2h) and thermal oxidation (600°C) on the corrosive behavior of Ti-6Al-4V, with serum proteins, at physiological temperature. Anodization produced a mixture of anatase and amorphous TiO2 nanopores and nanotubes, while the annealing process yielded an anatase/rutile mixture of TiO2 nanopores and nanotubes. The surface area was analyzed by the Brunauer-Emmett-Teller method and was estimated to be 3 orders of magnitude higher than that of polished control samples. Corrosion resistance was evaluated on the parameters of open circuit potential, corrosion potential, corrosion current density, passivation current density, polarization resistance and equivalent circuit modeling. Samples both anodized and thermally oxidized exhibited shifts of open circuit potential and corrosion potential in the noble direction, indicating a more stable nanoporous/nanotube layer, as well as lower corrosion current densities and passivation current densities than the smooth control. They also showed increased polarization resistance and diffusion limited charge transfer within the bulk oxide layer. The treatment groups studied can be ordered from greatest corrosion resistance to least as Anodized+Thermally Oxidized > Anodized > Smooth > Thermally Oxidized for the conditions investigated. This study concludes that anodized surface has a potential to prevent long term implant failure due to corrosion in a complex in-vivo environment.

  1. Haze, oxidation, and corrosion resistant diesel engine lubricant

    SciTech Connect

    Sung, R.L.; Zoleski, B.H.; O'Rourke, R.L.

    1987-11-10

    This patent describes a haze, oxidation, and corrosion resistant diesel engine lubricant composition, particularly useful in marine and railway diesel engines, contains 0.1-5.0 weight percent of a reaction product additive. The reaction product additive is produced by first reacting substantially equimolar amounts of an anhydride compound which is either a dibasic acid anhydride or isatoic anhydride and a hydrocarbon-substituted mono primary amine or ether amine at a temperature range of 50/sup 0/C-150/sup 0/C to produce an intermediate reaction product. The intermediate reaction product is thereafter further reacted at an elevated temperature with a substantially equimolar amount of a heterocyclic azole or polyalkylene polyamine compound to form the final reaction product.

  2. Corrosion testing of zirconia, beryllia and magnesia ceramics in molten alkali metal carbonates at 900 °C

    NASA Astrophysics Data System (ADS)

    Kaplan, Valery; Bendikov, Tatyana; Feldman, Yishay; Gartsman, Konstantin; Wachtel, Ellen; Lubomirsky, Igor

    2016-01-01

    An electrochemical cell containing molten Li2CO3-Li2O at 900 °C has been proposed for the conversion of the greenhouse gas CO2 to CO for chemical energy storage. In the current work, we have examined the corrosion resistance of zirconia, beryllia and magnesia ceramics at 900 °C in the Li2CO3-Li2O and Li-Na-K carbonate eutectic mixtures to identify suitable electrically insulating materials. Conclusions regarding material stability were based on elemental analysis of the melt, primarily via X-ray photoelectron spectroscopy, a particularly sensitive technique. It was found that magnesia is completely stable for at least 33 h in a Li2CO3-Li2O melt, while a combined lithium titanate/lithium zirconate layer forms on the zirconia ceramic as detected by XRD. Under the same melt conditions, beryllia shows considerable leaching into solution. In a Li-Na-K carbonate eutectic mixture containing 10.2 mol% oxide at 900 °C under standard atmospheric conditions, magnesia showed no signs of degradation. Stabilization of the zirconia content of the eutectic mixture at 0.01-0.02 at% after 2 h is explained by the formation of a lithium zirconate coating on the ceramic. On the basis of these results, we conclude that only magnesia can be satisfactorily used as an insulating material in electrolysis cells containing Li2CO3-Li2O melts.

  3. Resistive Memory for Harsh Electronics: Immunity to Surface Effect and High Corrosion Resistance via Surface Modification

    PubMed Central

    Huang, Teng-Han; Yang, Po-Kang; Lien, Der-Hsien; Kang, Chen-Fang; Tsai, Meng-Lin; Chueh, Yu-Lun; He, Jr-Hau

    2014-01-01

    The tolerance/resistance of the electronic devices to extremely harsh environments is of supreme interest. Surface effects and chemical corrosion adversely affect stability and operation uniformity of metal oxide resistive memories. To achieve the surrounding-independent behavior, the surface modification is introduced into the ZnO memristors via incorporating fluorine to replace the oxygen sites. F-Zn bonds is formed to prevent oxygen chemisorption and ZnO dissolution upon corrosive atmospheric exposure, which effectively improves switching characteristics against harmful surroundings. In addition, the fluorine doping stabilizes the cycling endurance and narrows the distribution of switching parameters. The outcomes provide valuable insights for future nonvolatile memory developments in harsh electronics. PMID:24638086

  4. Improving by postoxidation of corrosion resistance of plasma nitrocarburized AISI 316 stainless steels

    NASA Astrophysics Data System (ADS)

    Yenilmez, A.; Karakan, M.; Çelik, İ.

    2017-01-01

    Austenitic stainless steels are widely used in several industries such as chemistry, food, health and space due to their perfect corrosion resistance. However, in addition to corrosion resistance, the mechanic and tribological features such as wear resistance and friction are required to be good in the production and engineering of this type of machines, equipment and mechanic parts. In this study, ferritic (FNC) and austenitic (ANC) nitrocarburizing were applied on AISI 316 stainless steel specimens with perfect corrosion resistance in the plasma environment at the definite time (4 h) and constant gas mixture atmosphere. In order to recover corrosion resistance which was deteriorated after nitrocarburizing again, plasma postoxidation process (45 min) was applied. After the duplex treatment, the specimens' structural analyses with XRD and SEM methods, corrosion analysis with polarization method and surface hardness with microhardness method were examined. At the end of the studies, AISI 316 surface hardness of stainless steel increased with nitrocarburizing process, but the corrosion resistance was deteriorated with FNC (570 °C) and ANC (670 °C) nitrocarburizing. With the following of the postoxidation treatment, it was detected that the corrosion resistance became better and it approached its value before the process.

  5. The effects of argon ion bombardment on the corrosion resistance of tantalum

    NASA Astrophysics Data System (ADS)

    Ramezani, A. H.; Sari, A. H.; Shokouhy, A.

    2017-02-01

    Application of ion beam has been widely used as a surface modification method to improve surface properties. This paper investigates the effect of argon ion implantation on surface structure as well as resistance against tantalum corrosion. In this experiment, argon ions with energy of 30 keV and in doses of 1 × 1017-10 × 1017 ions/cm2 were used. The surface bombardment with inert gases mainly produces modified topography and morphology of the surface. Atomic Force Microscopy was also used to patterned the roughness variations prior to and after the implantation phase. Additionally, the corrosion investigation apparatus wear was applied to compare resistance against tantalum corrosion both before and after ion implantation. The results show that argon ion implantation has a substantial impact on increasing resistance against tantalum corrosion. After the corrosion test, scanning electron microscopy (SEM) analyzed the samples' surface morphologies. In addition, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. The purpose of this paper was to obtain the perfect condition for the formation of tantalum corrosion resistance. In order to evaluate the effect of the ion implantation on the corrosion behavior, potentiodynamic tests were performed. The results show that the corrosion resistance of the samples strongly depends on the implantation doses.

  6. Plasma Arc Melting (PAM) and Corrosion Resistance of Pure NiTi Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Tuissi, A.; Rondelli, G.; Bassani, P.

    2015-03-01

    Plasma arc melting (PAM) as a suitable non-contaminating melting route for manufacturing high-quality NiTi alloy was successfully examined. The corrosion resistance of PAM Nitinol was evaluated by both potentiodynamic and potentiostatic tests and compared with lower purity NiTi produced by vacuum induction melting (VIM). For the electro-polished surfaces, excellent corrosion resistance of NiTi comparable with the Ti alloys was found with no pitting up to 800 mV versus saturated calomel electrode in simulated body fluid at 37 °C. Potentiostatic results of PAM Nitinol indicate slightly better corrosion resistance than the lower quality VIM alloy.

  7. Improving the corrosion resistance of power metallurgy austenitic stainless steels through infiltration

    SciTech Connect

    Velasco, F.; Ibars, J.R.; Ruiz-Roman, J.M.; Torralba, J.M.; Ruiz-Prieto, J.M.

    1996-01-01

    Types 316L (UNS S31603) and 304L (UNS S30403) sintered stainless steels (SS) were produced in a laboratory furnace at 1,330 C and infiltrated with copper and bronze in different percentages to determine their effect on the corrosion resistance of the presintered SS. Corrosion resistance was studied by immersion in sulfuric, hydrochloric and nitric acids and by electrochemical potentiokinetic reactivation (EPR) tests. Both copper and bronze improved corrosion resistance highly in HCl and boiling H{sub 2}SO{sub 4}. Results of EPR and boiling H{sub 2}SO{sub 4} immersion tests showed good concordance.

  8. Substitution for chromium in 304 stainless steel. [effects on oxidation and corrosion resistance

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Barrett, C. A.

    1978-01-01

    An investigation was conducted to determine the effects of substituting less strategic elements for Cr on oxidation and corrosion resistance of AISI 304 stainless steel. Cyclic oxidation resistance was evaluated at 870 C. Corrosion resistance was determined by exposure of specimens to a boiling copper-rich solution of copper sulfate and sulfuric acid. Alloy substitutes for Cr included Al, Mn, Mo, Si, Ti, V, Y, and misch metal. A level of about 12% Cr was the minimum amount of Cr required for adequate oxidation and corrosion resistance in the modified composition 304 stainless steels. This represents a Cr saving of 33 percent. Two alloys containing 12% Cr plus 2% Al plus 2% Mo and 12% Cr plus 2.65% Si were identified which exhibited oxidation and corrosion resistance comparable to AISI 304 stainless steel.

  9. Superheater Corrosion Produced By Biomass Fuels

    SciTech Connect

    Sharp, William; Singbeil, Douglas; Keiser, James R

    2012-01-01

    About 90% of the world's bioenergy is produced by burning renewable biomass fuels. Low-cost biomass fuels such as agricultural wastes typically contain more alkali metals and chlorine than conventional fuels. Although the efficiency of a boiler's steam cycle can be increased by raising its maximum steam temperature, alkali metals and chlorine released in biofuel boilers cause accelerated corrosion and fouling at high superheater steam temperatures. Most alloys that resist high temperature corrosion protect themselves with a surface layer of Cr{sub 2}O{sub 3}. However, this Cr{sub 2}O{sub 3} can be fluxed away by reactions that form alkali chromates or volatilized as chromic acid. This paper reviews recent research on superheater corrosion mechanisms and superheater alloy performance in biomass boilers firing black liquor, biomass fuels, blends of biomass with fossil fuels and municipal waste.

  10. Structure Analysis Of Corrosion Resistant Thermal Sprayed Coatings On Low Alloy Steels

    SciTech Connect

    Chaliampalias, D.; Vourlias, G.; Pistofidis, N.; Pavlidou, E.; Stergiou, A.; Stergioudis, G.; Polychroniadis, E. K.

    2007-04-23

    Metallic coatings have been proved to reduce the rate of corrosion of steel in various atmospheres. In this work the structure of Al, Cu-Al and Zn thermal sprayed coatings is examined. The as formed coatings are extremely rough, and they are composed of several phases which increase corrosion resistance as it was determined Salt Spray Chamber tests.

  11. Increased corrosion resistance of the AZ80 magnesium alloy by rapid solidification.

    PubMed

    Aghion, E; Jan, L; Meshi, L; Goldman, J

    2015-11-01

    Magnesium (Mg) and Mg-alloys are being considered as implantable biometals. Despite their excellent biocompatibility and good mechanical properties, their rapid corrosion is a major impediment precluding their widespread acceptance as implantable biomaterials. Here, we investigate the potential for rapid solidification to increase the corrosion resistance of Mg alloys. To this end, the effect of rapid solidification on the environmental and stress corrosion behavior of the AZ80 Mg alloy vs. its conventionally cast counterpart was evaluated in simulated physiological electrolytes. The microstructural characteristics were examined by optical microscopy, SEM, TEM, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion, salt spraying, and potentiodynamic polarization. Stress corrosion resistance was assessed by Slow Strain Rate Testing. The results indicate that the corrosion resistance of rapidly solidified ribbons is significantly improved relative to the conventional cast alloy due to the increased Al content dissolved in the α-Mg matrix and the correspondingly reduced presence of the β-phase (Mg17 Al12 ). Unfortunately, extrusion consolidated solidified ribbons exhibited a substantial reduction in the environmental performance and stress corrosion resistance. This was mainly attributed to the detrimental effect of the extrusion process, which enriched the iron impurities and increased the internal stresses by imposing a higher dislocation density. In terms of immersion tests, the average corrosion rate of the rapidly solidified ribbons was <0.4 mm/year compared with ∼2 mm/year for the conventionally cast alloy and 26 mm/year for the rapidly solidified extruded ribbons.

  12. Corrosion-Resistant Container for Molten-Material Processing

    NASA Technical Reports Server (NTRS)

    Stern, Theodore G.; McNaul, Eric

    2010-01-01

    In a carbothermal process, gaseous methane is passed over molten regolith, which is heated past its melting point to a temperature in excess of 1,625 C. At this temperature, materials in contact with the molten regolith (or regolith simulant) corrode and lose their structural properties. As a result, fabricating a crucible to hold the molten material and providing a method of contact heating have been problematic. Alternative containment approaches use a large crucible and limit the heat zone of the material being processed, which is inefficient because of volume and mass constraints. Alternative heating approaches use non-contact heating, such as by laser or concentrated solar energy, which can be inefficient in transferring heat and thus require higher power heat sources to accomplish processing. The innovation is a combination of materials, with a substrate material having high structural strength and stiffness and high-temperature capability, and a coating material with a high corrosion resistance and high-temperature capability. The material developed is a molybdenum substrate with an iridium coating. Creating the containment crucible or heater jacket using this material combination requires only that the molybdenum, which is easily processed by conventional methods such as milling, electric discharge machining, or forming and brazing, be fabricated into an appropriate shape, and that the iridium coating be applied to any surfaces that may come in contact with the corrosive molten material. In one engineering application, the molybdenum was fashioned into a container for a heat pipe. Since only the end of the heat pipe is used to heat the regolith, the container has a narrowing end with a nipple in which the heat pipe is snugly fit, and the external area of this nipple, which contacts the regolith to transfer heat into it, is coated with iridium. At the time of this reporting, no single material has been found that can perform the functions of this combination

  13. 76 FR 69703 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Notice of Extension of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-09

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...) published a notice of initiation of the administrative review of the antidumping duty order on corrosion... results of this review. See Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic...

  14. 75 FR 77615 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Notice of Extension of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-13

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...) published a notice of initiation of the administrative review of the antidumping duty order on corrosion... results of this review. See Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic...

  15. General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods

    DTIC Science & Technology

    2009-09-01

    General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated... Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods Brian E. Placzankis Weapons and Materials Research Directorate...March 2006–October 2008 4. TITLE AND SUBTITLE General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD

  16. Corrosion-resistant multilayer coatings for the 28-75 nm wavelength region

    SciTech Connect

    Soufli, R; Fernandez-Perea, M; Al, E T

    2011-11-08

    Corrosion has prevented use of SiC/Mg multilayers in applications requiring good lifetime stability. We have developed Al-based barrier layers that dramatically reduce corrosion, while preserving high reflectance and low stress. The aforementioned advances may enable the implementation of corrosion-resistant, high-performance SiC/Mg coatings in the 28-75 nm region in applications such as tabletop EUV/soft x-ray laser sources and solar physics telescopes. Further study and optimization of corrosion barrier structures and coating designs is underway.

  17. 16 CFR 23.10 - Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INDUSTRIES § 23.10 Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant,” etc. (a) It is unfair or deceptive to: (1) Use the terms “corrosion proof,” “noncorrosive... the product will be immune from rust and other forms of corrosion during the life expectancy of...

  18. 16 CFR 23.10 - Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INDUSTRIES § 23.10 Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant,” etc. (a) It is unfair or deceptive to: (1) Use the terms “corrosion proof,” “noncorrosive... the product will be immune from rust and other forms of corrosion during the life expectancy of...

  19. White primer permits a corrosion-resistant coating of minimum weight

    NASA Technical Reports Server (NTRS)

    Albrecht, R. H.; Jensen, D. P.; Schnake, P.

    1966-01-01

    White primer for coating 2219 aluminum alloy supplies a base for a top coating of enamel. A formulation of pigments and vehicle results in a primer with high corrosion resistance and minimum film thickness.

  20. 2D Heterostructure coatings of hBN-MoS2 layers for corrosion resistance

    NASA Astrophysics Data System (ADS)

    Vandana, Sajith; Kochat, Vidya; Lee, Jonghoon; Varshney, Vikas; Yazdi, Sadegh; Shen, Jianfeng; Kosolwattana, Suppanat; Vinod, Soumya; Vajtai, Robert; Roy, Ajit K.; Sekhar Tiwary, Chandra; Ajayan, P. M.

    2017-02-01

    Heterostructures of atomically thin 2D materials could have improved physical, mechanical and chemical properties as compared to its individual components. Here we report, the effect of heterostructure coatings of hBN and MoS2 on the corrosion behavior as compared to coatings employing the individual 2D layer compositions. The poor corrosion resistance of MoS2 (widely used as wear resistant coating) can be improved by incorporating hBN sheets. Depending on the atomic stacking of the 2D sheets, we can further engineer the corrosion resistance properties of these coatings. A detailed spectroscopy and microscopy analysis has been used to characterize the different combinations of layered coatings. Detailed DFT based calculation reveals that the effect on the electrical properties due to atomic stacking is one of the major reasons for the improvement seen in corrosion resistance.

  1. Effect of Boron and Cerium on Corrosion Resistance of Cu -Fe -P Alloy

    NASA Astrophysics Data System (ADS)

    Zou, Jin; Lu, Lei; Lu, De-ping; Liu, Ke-Ming; Chen, Zhi-bao; Zhai, Qi-jie

    2016-03-01

    The effects of B and Ce on the corrosion resistance of Cu-0.22Fe-0.06P alloy were investigated by salt spray and electrochemical tests. The corrosion morphology was studied by scanning electron microscopy. The corrosion products were characterized by energy-dispersive x-ray spectroscopy and x-ray diffraction analysis. The impurity content was determined by inductively coupled plasma mass spectrometry. The conductivity was measured using an eddy current conductivity meter. The grains of Cu-0.22Fe-0.06P alloy were refined by the addition of B and Ce. The electrochemical corrosion process of alloy is retarded due to purification effect of B and Ce. After the addition of a trace amount of B, the corrosion resistance of the alloy decreased. The corrosion resistance of Cu-0.22Fe-0.06P-0.025B-0.05Ce was better than that of Cu-0.22Fe-0.06P-0.025B due to the fact that the purification effect of Ce is better than that of B. The main corrosion products of the Cu-Fe-P alloys in a NaCl solution are Cu2Cl(OH)3 and Cu2O. The addition of trace amounts of B and Ce did not change the components of the corrosion product.

  2. Effect of Chromium Addition to the Low Temperature Hot Corrosion Resistance of Platinum Modified Aluminide Coatings.

    DTIC Science & Technology

    1985-12-01

    Diffusion aluminide coatings were the first coatings developed for hot corrosion resistance. Aluminum is applied to the surface of the superalloy by a...D.H., "Mechanisms of Formation of Diffusion Aluminide Coatings on Nickel-oase Superalloys , Oxidation of Metals, v. 3, pp. 475-477, 1971. 17. Lehnert...Classification) E.FFECT OF CHROMIUJM ADDITION TO THE LOW TEMPERATURE HOT CORROSION RESISTANCE OF PLATINUM MODIFIED ALUMINIDE COATINGS 2 PERSONAL AUTHOR(S) Dust

  3. Development of Ferrium S53 High-Strength, Corrosion-Resistant Steel

    DTIC Science & Technology

    2009-01-01

    19 Figure 8. Surfaces of unpainted 15 - 5PH and S53 after 12 month beach exposureC Kure Beach...strength steel used in landing gear, and equivalent in corrosion resistance to the lower strength 15 - 5PH stainless steel used in actuators. It also...for using S53 in place of lower strength corrosion-resistant (CRES) steels such as 15 - 5PH , 17-4PH, and PH13-8Mo, which are used in applications

  4. Preparation and corrosion resistance of MAO/Ni-P composite coat on Mg alloy

    NASA Astrophysics Data System (ADS)

    Fan, Xizhi; Wang, Ying; Zou, Binglin; Gu, Lijian; Huang, Wenzhi; Cao, Xueqiang

    2013-07-01

    Microarc oxidation (MAO) coat was designed as an intermediate layer for the electroless plated Ni-P top coat, providing inert surface and necessary hardness for Mg alloy substrate. The composite coat was successfully prepared to improve the corrosion resistance of Mg alloy. The preparation and the characterization of the composite coat were investigated. The results show that the pre-treatment of MAO before electroless plating plays an important role in the deposition of compact composite coat. The activation (by HF solution) makes the MAO coat dense with uniform cracks which supply excellent bonding interface for Ni-P coat. Compared with monolithic MAO or Ni-P coat, the composite coat has excellent corrosion resistance and stable bonding interface. There is main pit corrosion at substrate after the corrosive medium penetrating through the whole coat. With the inert MAO interlayer, the electrochemical corrosion between the Ni-P and substrate is effectively inhibited.

  5. Interfacial valence electron localization and the corrosion resistance of Al-SiC nanocomposite

    PubMed Central

    Mosleh-Shirazi, Sareh; Hua, Guomin; Akhlaghi, Farshad; Yan, Xianguo; Li, Dongyang

    2015-01-01

    Microstructural inhomogeneity generally deteriorates the corrosion resistance of materials due to the galvanic effect and interfacial issues. However, the situation may change for nanostructured materials. This article reports our studies on the corrosion behavior of SiC nanoparticle-reinforced Al6061 matrix composite. It was observed that the corrosion resistance of Al6061 increased when SiC nanoparticles were added. Overall electron work function (EWF) of the Al-SiC nanocomposite increased, along with an increase in the corrosion potential. The electron localization function of the Al-SiC nanocomposite was calculated and the results revealed that valence electrons were localized in the region of SiC-Al interface, resulting in an increase in the overall work function and thus building a higher barrier to hinder electrons in the nano-composite to participate in corrosion reactions. PMID:26667968

  6. Effect of quenching method on the wear and corrosion resistance of stainless steel AISI 420 (TYPE 30Kh13)

    NASA Astrophysics Data System (ADS)

    Sola, R.; Giovanardi, R.; Veronesi, P.; Poli, G.

    2013-03-01

    The effect of different kinds of quenching, i.e., laser, vacuum, and induction ones, on the mechanical properties and wear and corrosion resistances of stainless steel AISI 420 is studied. It is shown that all the three kinds of heat treatment raise considerably the wear resistance of the steel due to growth in the hardness. Laser and vacuum quenching also increases the corrosion resistance. After induction quenching the resistance to corrosion is lower than in untreated steel.

  7. Enhanced Corrosion Resistance of a Transient Liquid Phase Bonded Nickel-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Adebajo, O. J.; Ojo, O. A.

    2017-01-01

    Electrochemical analysis of corrosion performance of a transient liquid phase (TLP) bonded nickel-based superalloy was performed. The TLP bonding process resulted in significant reduction in corrosion resistance due to the formation of non-equilibrium solidification reaction micro-constituents within the joint region. The corrosion resistance degradation is completely eliminated through a new application of composite interlayer that had been previously considered unusable for joining single-crystal superalloys. The effectiveness of the new approach becomes more pronounced as the severity of environment increases.

  8. Multi-functional hybrid coatings containing silica nanoparticles and anti-corrosive acrylate monomer for scratch and corrosion resistance.

    PubMed

    Seo, Ji Yeon; Han, Mijeong

    2011-01-14

    Multi-functional hybrid coatings having both anti-corrosion and scratch resistance were prepared from modified silica nanoparticles and functional acrylates. To improve the dispersion properties of silica nanoparticles in the organic/inorganic hybrid coatings, the surface of the nanoparticles was modified with γ-methacryloxypropyltrimethoxysilane. The coating solution could be prepared by mixing modified silica nanoparticles, tetrasiloxane acrylate, di-acrylate monomer containing an anti-corrosion functional group, acrylic acid, and an initiator in a solvent. The mixture was then dip-coated on iron substrates and finally polymerized by ultraviolet (UV) irradiation. Corrosion and scratch resistance of the coated iron was evaluated by electrochemical impedance spectroscopy (EIS) and a pencil hardness test, respectively. From the EIS results, the coatings with tetrasiloxane acrylate and di-acrylate did not show any decrease in impedance or phase angle, even after 50 days' exposure to 0.1 M NaCl electrolyte, whereas the conventional acrylate coatings started to fail after only 24 h. A hybrid coating containing the amine-quinone functional group exhibited excellent corrosion protection properties with 4-5H pencil hardness.

  9. Corrosion of Carbon Steel and Corrosion-Resistant Rebars in Concrete Structures Under Chloride Ion Attack

    NASA Astrophysics Data System (ADS)

    Mohamed, Nedal; Boulfiza, Mohamed; Evitts, Richard

    2013-03-01

    Corrosion of reinforced concrete is the most challenging durability problem that threatens reinforced concrete structures, especially structures that are subject to severe environmental conditions (i.e., highway bridges, marine structures, etc.). Corrosion of reinforcing steel leads to cracking and spalling of the concrete cover and billions of dollars are spent every year on repairing such damaged structures. New types of reinforcements have been developed to avoid these high-cost repairs. Thus, it is important to study the corrosion behavior of these new types of reinforcements and compare them to the traditional carbon steel reinforcements. This study aimed at characterizing the corrosion behavior of three competing reinforcing steels; conventional carbon steel, micro-composite steel (MMFX-2) and 316LN stainless steel, through experiments in carbonated and non-carbonated concrete exposed to chloride-laden environments. Synthetic pore water solutions have been used to simulate both cases of sound and carbonated concrete under chloride ions attack. A three-electrode corrosion cell is used for determining the corrosion characteristics and rates. Multiple electrochemical techniques were applied using a Gamry PC4™ potentiostat manufactured by Gamry Instruments (Warminster, PA). DC corrosion measurements were applied on samples subjected to fixed chloride concentration in the solution.

  10. The corrosion resistance and neutron-absorbing properties of coatings based on amorphous alloys

    NASA Astrophysics Data System (ADS)

    Sevryukov, O. N.; Polyansky, A. A.

    2016-04-01

    The object of the present study was the corrosion-resistant amorphizing alloys with an increased content of boron for cladding the surface of metals, rapidly quenched alloys without boron for protective coatings on a high-boron cladding layer, as well as steel samples with a protective coating with a high content of boron and without boron. The aim of the work is to investigate the corrosion resistance of a coating in water at the temperature of 40 °C in conditions of an open access of oxygen for 1000 h, as well as the features of the microstructure of clad samples before and after the corrosion tests. New data on the corrosion resistance of Cr18Ni10Ti steel samples with a protective layer from a rapidly quenched alloy Ni-19Cr-10Si (in wt.%) on a high-boron coating have been obtained.

  11. Corrosion resistance and antithrombogenic behavior of La and Nd ion implanted stainless steels

    SciTech Connect

    Jing, F. J.; Jin, F. Y.; Liu, Y. W.; Wan, G. J.; Liu, X. M.; Zhao, X. B.; Fu, R. K. Y.; Leng, Y. X.; Huang, N.; Chu, Paul K.

    2006-09-15

    Lanthanide ions such as lanthanum (La) and neodymium (Nd) were implanted into 316 stainless steel samples using metal vapor vacuum arc to improve the surface corrosion resistance and antithrombogenic properties. X-ray photoelectron spectroscopy shows that lanthanum and neodymium exist in the +3 oxidation state in the surface layer. The corrosion properties of the implanted and untreated control samples were investigated utilizing electrochemical tests and our results show that La and Nd implantations enhance the surface corrosion resistance. In vitro activated partial thromboplastin time (APTT) tests were used to evaluate the antithrombogenic properties. The APTT time of the implanted samples was observed to be prolonged compared to that of the unimplanted stainless steel control. La and Nd ion implantations can be used to improve the surface corrosion resistance and biomedical properties of 316 stainless steels.

  12. Corrosion Resistance of Powder Metallurgy Processed TiC/316L Composites with Mo Additions

    NASA Astrophysics Data System (ADS)

    Lin, Shaojiang; Xiong, Weihao

    2015-06-01

    To find out the effects of Mo addition on corrosion resistance of TiC/316L stainless steel composites, TiC/316L composites with addition of different contents of Mo were prepared by powder metallurgy. The corrosion resistance of these composites was evaluated by the immersion tests and polarization curves experiments. Results indicated that Mo addition decreased the corrosion rates of TiC/316L composites in H2SO4 solution in the case of Mo content below 2% whereas it displayed an opposite effect when Mo content was above that value. It was found that with an increase in the Mo content, the pitting corrosion resistance increased monotonically for TiC/316L composites in NaCl solution.

  13. Electrodeposition of high corrosion resistance Cu/Ni-P coating on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Shan; Cao, Fahe; Chang, Linrong; Zheng, JunJun; Zhang, Zhao; Zhang, Jianqing; Cao, Chunan

    2011-08-01

    High corrosion resistance Cu/Ni-P coatings were electrodeposited on AZ91D magnesium alloy via suitable pretreatments, such as one-step acid pickling-activation, once zinc immersion and environment-friendly electroplated copper as the protective under-layer, which made Ni-P deposit on AZ91D Mg alloy in acid plating baths successfully. The pH value and current density for Ni-P electrodeposition were optimized to obtain high corrosion resistance. With increasing the phosphorous content of the Ni-P coatings, the deposits were found to gradually transform to amorphous structure and the corrosion resistance increased synchronously. The anticorrosion ability of AZ91D Mg alloy was greatly improved by the amorphous Ni-P deposits, which was investigated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The corrosion current density ( Icorr) of the coated Mg alloy substrate is about two orders of magnitude less than that of the uncoated.

  14. Effect of high repetition laser shock peening on biocompatibility and corrosion resistance of magnesium

    NASA Astrophysics Data System (ADS)

    Caralapatti, Vinodh Krishna; Narayanswamy, Sivakumar

    2017-02-01

    Magnesium, as a biomaterial has the potential to replace conventional implant materials owing to its numerous advantages. However, high corrosion rate is a major obstacle that has to be addressed for its implementation as implants. This study aims to evaluate the feasibility and effects of High Repetition Laser Shock Peening (HRLSP) on biocompatibility and corrosion resistance of Mg samples and as well as to analyze the effect of operational parameters such as peening with overlap on corrosion rate. From the results obtained using hydrogen evolution and mass loss methods, it was found that corrosion rates of both 0% overlap and 66% overlap peened samples reduced by more than 50% compared to that of unpeened sample and sample peened with 66% overlap exhibited least corrosion. The biocompatibility of peened Mg samples was also enhanced as there was neither rapid pH variation nor large hydrogen bubble formation around samples.

  15. Fracture-tough, corrosion-resistant bearing steels

    NASA Technical Reports Server (NTRS)

    Olson, Gregory B.

    1990-01-01

    The fundamental principles allowing design of stainless bearing steels with enhanced toughness and stress corrosion resistance has involved both investigation of basic phenomena in model alloys and evaluation of a prototype bearing steel based on a conceptual design exercise. Progress in model studies has included a scanning Auger microprobe (SAM) study of the kinetics of interfacial segregation of embrittling impurities which compete with the kinetics of alloy carbide precipitation in secondary hardening steels. These results can define minimum allowable carbide precipitation rates and/or maximum allowable free impurity contents in these ultrahigh strength steels. Characterization of the prototype bearing steel designed to combine precipitated austenite transformation toughening with secondary hardening shows good agreement between predicted and observed solution treatment response including the nature of the high temperature carbides. An approximate equilibrium constraint applied in the preliminary design calculations to maintain a high martensitic temperature proved inadequate, and the solution treated alloy remained fully austenitic down to liquid nitrogen temperature rather than transforming above 200 C. The alloy can be martensitically transformed by cryogenic deformation, and material so processed will be studied further to test predicted carbide and austenite precipitation behavior. A mechanistically-based martensitic kinetic model was developed and parameters are being evaluated from available kinetic data to allow precise control of martensitic temperatures of high alloy steels in future designs. Preliminary calculations incorporating the prototype stability results suggest that the transformation-toughened secondary-hardening martensitic-stainless design concept is still viable, but may require lowering Cr content to 9 wt. pct. and adding 0.5 to 1.0 wt. pct. Al. An alternative design approach based on strain-induced martensitic transformation during

  16. Corrosion resistance of aluminum-magnesium alloys in glacial acetic acid

    SciTech Connect

    Zaitseva, L.V.; Romaniv, V.I.

    1984-05-01

    Vessels for the storage and conveyance of glacial acetic acid are produced from ADO and AD1 aluminum, which are distinguished by corrosion resistance, weldability and workability in the hot and cold conditions but have low tensile strength. Aluminum-magnesium alloys are stronger materials close in corrosion resistance to technical purity aluminum. An investigation was made of the basic alloying components on the corrosion resistance of these alloys in glacial acetic acid. Both the base metal and the weld joints were tested. With an increase in temperature the corrosion rate of all of the tested materials increases by tens of times. The metals with higher magnesium content show more pitting damage. The relationship of the corrosion resistance of the alloys to magnesium content is confirmed by the similar intensity of failure of the joint metal of all of the investigated alloys and by electrochemical investigations. The data shows that AMg3 alloy is close to technically pure ADO aluminum. However, the susceptibility of even this material to local corrosion eliminates the possibility of the use of aluminum-magnesium alloys as reliable constructional materials in glacial acetic acid.

  17. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    PubMed

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

  18. Thin boron phosphide coating as a corrosion-resistant layer

    DOEpatents

    Not Available

    1982-08-25

    A surface prone to corrosion in corrosive environments is rendered anticorrosive by CVD growing a thin continuous film, e.g., having no detectable pinholes, thereon, of boron phosphide. In one embodiment, the film is semiconductive. In another aspect, the invention is an improved photoanode, and/or photoelectrochemical cell with a photoanode having a thin film of boron phosphide thereon rendering it anticorrosive, and providing it with unexpectedly improved photoresponsive properties.

  19. Effect of Waterproofing Admixtures on the Flexural Strength and Corrosion Resistance of Concrete

    NASA Astrophysics Data System (ADS)

    Geetha, A.; Perumal, P.

    2012-02-01

    This paper deals about the flexural strength and corrosion behaviour of concrete using waterproofing admixtures. The effect of waterproofing admixtures on the corrosion behaviour of RCC specimen has been studied by conducting accelerated corrosion test. To identify the effect of corrosion in pull out strength, corrosion process was induced by means of accelerated corrosion procedure. To accelerate the reinforcement corrosion, direct electric current was impressed on the rebar embedded in the specimen using a DC power supply system that has a facility to adjust voltage. The addition of waterproofing admixtures also shows the improvement in the flexural strength of concrete has been studied by conducting flexural strength tests on the concrete prism specimen of size 100 × 100 × 500 mm with and without admixtures for various dosages and various curing periods of 7 and 28 days. The results showed that the presence of waterproofing admixtures always improves the corrosion resistance and thus increases the strength of concrete due to the hydrophobic action of waterproofing admixtures.

  20. Study of Corrosion Resistance Improvement by Metallic Coating for Overhead Transmission Line Conductor

    NASA Astrophysics Data System (ADS)

    Isozaki, Masanori; Adachi, Kouichi; Hita, Takanori; Asano, Yuji

    Applying anti-corrosion grease and aluminum clad steel (AC) wires to ACSR has adopted as general methods to prevent overhead transmission line conductors and/or wires from corrosion. However, there are some cases that ineffectiveness of those means are reported on some transmission lines passing through acid atmosphere in the vicinity of a factory exhausting acid smoke. The feature of the corrosion caused by acid atmosphere is to show a higher speed in its progressing as well known. As means against such acid corrosion, application of high purity aluminum, selective removal of inter-metallic compound in aluminum and plastic coating wires has been reported before, and each has both of advantage and disadvantage actually. In the former letter, we reported the new type of anti-corrosion grease that shows an excellent property against acid atmosphere as well as in a salty circumstance. Here presents a new type of anti-corrosion technology of applying high corrosion resistance aluminum alloy or zinc coatings on each component wires of a conductor that we succeed in developing through a serial study of anti-corrosion methods on overhead transmission lines.

  1. Corrosion-resistant amorphous metallic films of Mo49Cr33B18 alloy

    NASA Technical Reports Server (NTRS)

    Ramesham, R.; Distefano, S.; Fitzgerald, D.; Thakoor, A. P.; Khanna, S. K.

    1987-01-01

    Corrosion-resistant amorphous metallic alloy films of Mo49Cr33B18 with a crystallization temperature of 590 C were deposited onto glass and quartz substrates by magnetron sputter-quench technique. The amorphous nature of the films was confirmed by their diffuse X-ray diffraction patterns. The deposited films are densely packed (zone T) and exhibit low stress and good adhesion to the substrate. Corrosion current of as-deposited coating of MoCrB amorphous metallic alloy is approximately three orders of magnitude less than the corrosion current of 304 stainless steel in 1N H2SO4 solution.

  2. Corrosive Resistant Diamond Coatings for the Acid Based Thermo-Chemical Hydrogen Cycles

    SciTech Connect

    Mark A. Prelas

    2009-06-25

    This project was designed to test diamond, diamond-like and related materials in environments that are expected in thermochemical cycles. Our goals were to build a High Temperature Corrosion Resistance (HTCR) test stand and begin testing the corrosive properties of barious materials in a high temperature acidic environment in the first year. Overall, we planned to test 54 samples each of diamond and diamond-like films (of 1 cm x 1 cm area). In addition we use a corrosion acceleration method by treating the samples at a temperature much larger than the expected operating temperature. Half of the samples will be treated with boron using the FEDOA process.

  3. The corrosion resistance of zinc coatings in the presence of boron-doped detonation nanodiamonds (DND)

    NASA Astrophysics Data System (ADS)

    Burkat, G. K.; Alexandrova, G. S.; Dolmatov, V. Yu; Osmanova, E. D.; Myllymäki, V.; Vehanen, A.

    2017-02-01

    The effect of detonation nanodiamonds, doped with boron (boron-DND) in detonation synthesis on the process of zinc electrochemical deposition from zincate electrolyte is investigated. It is shown that the scattering power (coating uniformity) increases 2-4 times (depending on the concentration of DND-boron electrolyte conductivity does not change, the corrosion resistance of Zn- DND -boron coating increases 2.6 times in 3% NaCl solution (corrosion currents) and 3 times in the climatic chamber.

  4. Investigating the Effects of Low Temperature Annealing of Amorphous Corrosion Resistant Alloys.

    DTIC Science & Technology

    1980-11-01

    24 vii BACKGROUND The advent of amorphous ’ alloys containing film -forming elements such as chromium has led to intensive research into corrosion...hypothesis is supported by evidence that passive films formed on Fe-Ni-Cr-P-C alloys are similar in structure to those observed on crystalline stainless...steels. 5 ’ It has also been shown that phosphorus enhances corrosion resistance, presumably by enriching the passive film in hydrated chromium

  5. Iron-based alloys with corrosion resistance to oxygen-sulfur mixed gases

    DOEpatents

    Natesan, K.

    1992-11-17

    An iron-based alloy with improved performance with exposure to oxygen-sulfur mixed gases with the alloy containing about 9--30 wt. % Cr and a small amount of Nb and/or Zr implanted on the surface of the alloy to diffuse a depth into the surface portion, with the alloy exhibiting corrosion resistance to the corrosive gases without bulk addition of Nb and/or Zr and without heat treatment at temperatures of 1000--1100 C. 7 figs.

  6. Iron-based alloys with corrosion resistance to oxygen-sulfur mixed gases

    DOEpatents

    Natesan, Krishnamurti

    1992-01-01

    An iron-based alloy with improved performance with exposure to oxygen-sulfur mixed gases with the alloy containing about 9-30 wt. % Cr and a small amount of Nb and/or Zr implanted on the surface of the alloy to diffuse a depth into the surface portion, with the alloy exhibiting corrosion resistance to the corrosive gases without bulk addition of Nb and/or Zr and without heat treatment at temperatures of 1000.degree.-1100.degree. C.

  7. Advanced Corrosion-Resistant Zr Alloys for High Burnup and Generation IV Applications

    SciTech Connect

    Arthur Motta; Yong Hwan Jeong; R.J. Comstock; G.S. Was; Y.S. Kim

    2006-10-31

    The objective of this collaboration between four institutions in the US and Korea is to demonstrate a technical basis for the improvement of the corrosion resistance of zirconium-based alloys in more extreme operating environments (such as those present in severe fuel duty,cycles (high burnup, boiling, aggressive chemistry) andto investigate the feasibility (from the point of view of corrosion rate) of using advanced zirconium-based alloys in a supercritical water environment.

  8. Corrosion resistant thermal barrier coating. [protecting gas turbines and other engine parts

    NASA Technical Reports Server (NTRS)

    Levine, S. R.; Miller, R. A.; Hodge, P. E. (Inventor)

    1981-01-01

    A thermal barrier coating system for protecting metal surfaces at high temperature in normally corrosive environments is described. The thermal barrier coating system includes a metal alloy bond coating, the alloy containing nickel, cobalt, iron, or a combination of these metals. The system further includes a corrosion resistant thermal barrier oxide coating containing at least one alkaline earth silicate. The preferred oxides are calcium silicate, barium silicate, magnesium silicate, or combinations of these silicates.

  9. Preparation and testing of corrosion and spallation-resistant coatings

    SciTech Connect

    Hurley, John P.; Cavalli, Matthew N.

    2016-06-30

    The goal of this project was to take a recently developed method of bonding oxide dispersion-strengthened (ODS) FeCrAl plating to nickel superalloys closer to commercial use in syngas-fired turbines. The project was designed to better understand and develop the bonding process and to determine if plating APMT®, a specific highly oxidation-resistant ODS FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The superalloys investigated for protection were CM247LC and Rene® 80, both alumina scale-forming alloys. The method for bonding the APMT plate to the superalloys is called evaporative metal bonding, which involves placing a thin foil of zinc between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the zinc melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The zinc then diffuses through the alloys and evaporates from their surfaces, creating a bond between the APMT and the superalloy that is stronger than the APMT itself. Testing showed that the diffusivity of zinc in both APMT and CM247LC is quite similar at 700°C but 15 times higher in the APMT at 1214°C. Coefficients of thermal expansion were determined for each of the alloys as a function of temperature. This information was entered into a finite-element model using ANSYS, which was used to design a clamping jig for pressing the APMT to the superalloys at the bonding temperature. Scanning electron microscopy analyses of representative joints showed that no zinc remained in the alloys after bonding Unfortunately, the analyses also showed some small pieces of broken aluminum oxide scale near the bond lines, indicating that its scale was not sufficiently removed during prebonding cleaning. Samples from each of the bonded blocks were sent to Siemens for

  10. Corrosion Resistance Analysis of Sintered NdFeB Magnets Using Ultrasonic-Aided EDM Method

    NASA Astrophysics Data System (ADS)

    Li, L.; Wei, X. T.; Li, Z. Y.; Cheng, X.

    2015-01-01

    Sintered neodymium-iron-boron (NdFeB) permanent magnets are widely used in many fields because of their excellent magnetic property. However, their poor corrosion resistance has been cited as a potential problem that limits their extensive application. This paper presents an experimental investigation into the improvement of surface corrosion resistance with the ultrasonic-aided electrical discharge machining (U-EDM) method. A scanning electron microscope was used to analyze the surface morphology of recast layers formed through the EDM and U-EDM processes. The chemical structure and elements of these recast layers were characterized using x-ray diffraction and energy dispersive spectroscopy. Corrosion resistance was also studied by means of potentiodynamic polarization, electrochemical impedance spectroscopy, and immersion tests in 0.5 mol/L H2SO4 solution. Experimental results show that an amorphous structure was formed in the recast layer during the EDM and U-EDM processes and that this structure could improve the corrosion resistance of sintered NdFeB magnets. Moreover, the corrosion resistance of U-EDM-treated surface was better than that of the EDM-treated surface.

  11. High-strength economically alloyed corrosion-resistant steels with the structure of nitrogen martensite

    NASA Astrophysics Data System (ADS)

    Bannykh, O.; Blinov, V.; Lukin, E.

    2016-04-01

    The use of nitrogen as the main alloying element allowing one both to increase the corrosion resistance and mechanical properties of steels and to improve their processability is a new trend in physical metallurgy of high-strength corrosion resistant steels. The principles of alloying, which are developed for high-nitrogen steel in IMET RAS, ensure the formation of the structure, which contains predetermined amounts of martensite (70-80%) and austenite (20-30%) and is free from δ-ferrite, σ-phase, and Cr23C6 carbide. These principles were used as the base for the creation of new high-strength corrosion-resistant weldable and deformable 0Kh16AN5B, 06Kh16AN4FD, 08Kh14AN4MDB, 09Kh16AN3MF, 27Kh15AN3MD2, 40Kh13AN3M2, and 19Kh14AMB steels, which are operative at temperatures ranging from - 70 to 400°C. The developed nitrogen-containing steels compared with similar carbon steels are characterized by a higher resistance to pitting and crevice corrosion and are resistant to stress corrosion cracking. The new steels successfully passed trial tests as heavy duty articles.

  12. Nano Structured Plasma Spray Coating for Wear and High Temperature Corrosion Resistance Applications

    NASA Astrophysics Data System (ADS)

    Ghosh, D.; Shukla, A. K.; Roy, H.

    2014-04-01

    The nano structured coating is a major challenge today to improve the different mechanical properties, wear and high temperature corrosion resistance behaviour of different industrial alloys. This paper is a review on synthesis of nano powder, plasma spraying methods, techniques of nano structured coating by plasma spray method, mechanical properties, tribological properties and high temperature corrosion behaviour of nano structured coating. Nano structured coatings of ceramic powders/composites are being developed for wide variety of applications like boiler, turbine and aerospace industries, which requires the resistance against wear, corrosion, erosion etc. The nano sized powders are subjected to agglomeration by spray drying, after which nano structured coating can be successfully applied over the substrate. Nano structured coating shows improved mechanical wear resistance and high temperature corrosion resistance. The significant improvement of wear and corrosion resistance is mainly attributed to formation of semi molten nano zones in case of nano structured coatings. The future scope of application of nano structured coating has also been highlighted in this paper.

  13. Electrophoretic deposition of colloidal particles on Mg with cytocompatibility, antibacterial performance, and corrosion resistance.

    PubMed

    Sun, Jiadi; Zhu, Ye; Meng, Long; Chen, Peng; Shi, Tiantian; Liu, Xiaoya; Zheng, Yufeng

    2016-11-01

    Magnesium (Mg) has recently received increasing attention due to its unique biological performance, including cytocompatibility, antibacterial and biodegradable properties. However, rapid corrosion in physiological environment and potential toxicity limits its clinical applications. To improve the corrosion resistance meanwhile not compromise other excellent performance, self-assembled colloidal particles were deposited onto magnesium surfaces in ethanol by a simple and effective electrophoretic deposition (EPD) method. The fabricated functional nanostructured coatings were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses, and scanning electron microscopy (SEM). The electrochemical test, pH value, and Mg ion concentration data show that the corrosion resistance of Mg samples is enhanced appreciably after surface treatment. In vitro cellular response and antibacterial capability of the modified Mg substrates are performed. Significantly increased cell adhesion and viability are observed from the coated Mg samples, and the amounts of adherent bacteria on the treated Mg surfaces diminish remarkably compared to the bare Mg. Furthermore, the bare and coated Mg samples were implanted in New Zealand white rabbits for 12 weeks to examine the in vivo long-term corrosion performance and in situ inflammation behavior. The experiment results confirmed that compared with bare Mg substrate the corrosion and foreign-body reactions of the coated Mg samples were suppressed. The above results suggested that our coatings, which effectively enhance the biocompatibility, antimicrobial properties, and corrosion resistance of Mg substrate, provide a simple and practical strategy to expedite clinical acceptance of biodegradableMg and its alloys.

  14. The fabricability and corrosion resistance of several Al-Cu-Li aerospace alloys

    SciTech Connect

    Walsh, D.W.; Danford, M.; Sanders, J.

    1996-12-31

    Al-Li-Cu alloys are attractive to the aerospace industry. The high specific strength and stiffness of these alloys will improve lift efficiency, fuel economy, performance and increase payload capabilities. The objectives of this study were to measure the fabricability of Al 2195 (Al-4Cu-1Li) and to assess the effect of welding on corrosion behavior. Al 2219 samples were used in parallel tests to provide a baseline for the data generated. In this study samples were exposed to 3.5% NaCl and mild corrosive water solutions in both the as received and as welded conditions. Fabricability was assessed using Gleeble testing, Varestraint testing and differential scanning calorimetry (DSC). Results indicate that Alloy 2195 is much more susceptible to hot cracking than Al 2219, and that cracking sensitivity is a strong function of chemical composition within specification ranges for Al 2195. Furthermore, for base metal samples, corrosion in mild corrosive water was more severe than corrosion in salt water. In addition, welding increases the corrosion rate in Al 2195 and 2219, and causes severe localization in Al 2195. Furthermore, autogenously welded Al 2195 samples were more susceptible to attack than heterogeneously welded Al 2195 samples and autogenously welded Al2219 samples were less susceptible to corrosion than autogenously welded Al 2195 samples. Heterogeneously welded samples in both materials had high corrosion rates, but only the Al 2195 material was subject to localization of attack. The partially melted zones of Al 2195 samples were subject to severe, focused attack. In all cases, interdendritic constituents in welded areas and intergranular constituents in base material were cathodic to the Al rich matrix materials. Fabricability and corrosion resistance were correlated to material microstructure using optical microscopy, scanning electron microscopy, electron probe microanalysis, polarization resistance and environmental scanning electron microscopy.

  15. Preparation and Testing of Corrosion and Spallation-Resistant Coatings

    SciTech Connect

    Hurley, John

    2015-11-01

    This Energy & Environmental Research Center (EERC) project is designed to determine if plating APMT®, a specific highly oxidation-resistant oxide dispersion-strengthened FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The method for joining the APMT plate to the superalloys is called evaporative metal bonding and involves placing a thin foil of zinc between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the zinc melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The zinc then diffuses through the alloys and evaporates from their surfaces. During this annual reporting period, the finite element model was completed and used to design clamping jigs to hold the APMT plate to the larger blocks of superalloys during the bonding process. The clamping system was machined from titanium–zirconium–molybdenum and used to bond the APMT plate to the superalloy blocks. The bond between the APMT plate was weak for one of each of the superalloy blocks. We believe that this occurred because enough oxidation had occurred on the surface of the parts as a result of a 1-month time period between sandblasting to prepare the parts and the actual bonding process. The other blocks were, therefore, bonded within 1 day of preparing the parts for bonding, and their joints appear strong. Scanning electron microscopy analyses of representative joints showed that no zinc remained in the alloys after bonding. Also, phases rich in hafnium and tantalum had precipitated near the bond line in the APMT. Iron from the APMT had diffused into the superalloys during bonding, more extensively in the CM247LC than in the Rene 80. Nickel from the superalloys had diffused into the APMT, again more extensively in the joint with the CM247LC than

  16. Corrosion-resistant multilayer structures with improved reflectivity

    DOEpatents

    Soufli, Regina; Fernandez-Perea, Monica; Robinson, Jeff C.

    2013-04-09

    In one general embodiment, a thin film structure includes a substrate; a first corrosion barrier layer above the substrate; a reflective layer above the first corrosion barrier layer, wherein the reflective layer comprises at least one repeating set of sub-layers, wherein one of the sub-layers of each set of sub-layers being of a corrodible material; and a second corrosion barrier layer above the reflective layer. In another general embodiment, a system includes an optical element having a thin film structure as recited above; and an image capture or spectrometer device. In a further general embodiment, a laser according to one embodiment includes a light source and the thin film structure as recited above.

  17. Effects of porosity on corrosion resistance of Mg alloy foam produced by powder metallurgy technology

    SciTech Connect

    Aghion, E. Perez, Y.

    2014-10-15

    Magnesium alloy foams have the potential to serve as structural material for regular light-weight applications as well as for biodegradable scaffold implants. However, their main disadvantage relates to the high reactivity of magnesium and consequently their natural tendency to corrode in regular service conditions and in physiological environments. The present study aims at evaluating the effect of porosity on the corrosion resistance of MRI 201S magnesium alloy foams in 0.9% NaCl solution and in phosphate buffer saline solution as a simulated physiological electrolyte. The magnesium foams were produced by powder metallurgy technology using space-holding particles to control the porosity content. Machined chips were used as raw material for the production of Mg alloy powder by milling process. The microstructure of the foams was examined using optical and scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analysis. The corrosion behavior was evaluated by immersion test and potentiodynamic polarization analysis. The results obtained clearly demonstrate that the porosity has a significant effect on the corrosion resistance of the tested foams. Foams with 14–19% porosity have a corrosion rate of 4–10 mcd and 7–15 mcd in NaCl and phosphate buffer saline solution, respectively, compared to only 0.10 mcd for the same alloy in as cast conditions. This increased corrosion degradation of the Mg foams by more than one order of magnitude compared to the cast alloy may limit their potential application in regular and physiological environments. - Highlights: • Porosity has a detrimental effect on corrosion resistance of MRI 201S Mg foams. • 14–19% porosity increases the corrosion rate by more than one order of magnitude. • Accelerated corrosion limits the use of foams in regular/physiological environments.

  18. Corrosion resistance evaluation of Pd-free Ag-Au-Pt-Cu dental alloys.

    PubMed

    Fujita, Takeshi; Shiraishi, Takanobu; Takuma, Yasuko; Hisatsune, Kunihiro

    2011-01-01

    The corrosion resistance of nine experimental Pd-free Ag-Au-Pt-Cu dental alloys in a 0.9% NaCl solution was investigated using cyclic voltammetry (CV), optical microscopy, and scanning electron microscopy (SEM). CV measurements revealed that the breakdown potential (E(bd)) and zero current potential (E(zc)) increased with increasing Au/(Au+Ag) atomic ratio. Thus, the Au/(Au+Ag) atomic ratio, but not the Cu content, influenced the corrosion resistance of Ag-Au-Pt-Cu alloys. After the forward scan of CV, both optical and scanning electron microscope images showed that in all the experimental alloys, the matrix phase was corroded but not the second phase. From corrosion resistance viewpoint, the Ag-Au-Pt-Cu alloys seemed to be suitable for clinical application.

  19. Optimization of Oxidation Temperature for Commercially Pure Titanium to Achieve Improved Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Bansal, Rajesh; Singh, J. K.; Singh, Vakil; Singh, D. D. N.; Das, Parimal

    2017-03-01

    Thermal oxidation of commercially pure titanium (cp-Ti) was carried out at different temperatures, ranging from 200 to 900 °C to achieve optimum corrosion resistance of the thermally treated surface in simulated body fluid. Scanning electron microscopy, x-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy techniques were used to characterize the oxides and assess their protective properties exposed in the test electrolyte. Maximum resistance toward corrosion was observed for samples oxidized at 500 °C. This was attributed to the formation of a composite layer of oxides at this temperature comprising Ti2O3 (titanium sesquioxide), anatase and rutile phases of TiO2 on the surface of cp-Ti. Formation of an intact and pore-free oxide-substrate interface also improved its corrosion resistance.

  20. Influence of electrolytic treatment time on the corrosion resistance of Ni-Ti orthodontic wire.

    PubMed

    Kaneto, Maki; Namura, Yasuhiro; Tamura, Takahiko; Shimizu, Noriyoshi; Tsutsumi, Yusuke; Hanawa, Takao; Yoneyama, Takayuki

    2013-01-01

    The purpose of this study was to examine the use of electrolytic treatment, which can improve the corrosion resistance of Ni-Ti orthodontic wires, to minimize adverse effects. Electrolytic treatment of Ni-Ti wires was performed in a solution composed of glycerol and lactic acid for 5, 15, or 30 min. The anodic polarization test, three-point bending test, and X-ray photoelectron spectroscopic analysis of the wire surface were performed to explore an optimal treatment condition. Breakdown potentials of treated wires increased with increasing treatment time and higher corrosion resistance was obtained by performing the electrolytic treatment for more than 5 min. The relative concentration of nickel in the layer was decreased in inverse proportion to the treatment time. The results suggest that the commercial Ni-Ti wire with low corrosion resistance can be improved by the electrolytic treatment for more than 5 min.

  1. Microstructure and corrosion resistance of phytic acid conversion coatings for magnesium alloy

    NASA Astrophysics Data System (ADS)

    Cui, Xiufang; Li, Qingfen; Li, Ying; Wang, Fuhui; Jin, Guo; Ding, Minghui

    2008-12-01

    In this paper, a new innoxious and pollution-free chemical protective coating for magnesium alloys, phytic acid conversion coating, was prepared. The conversion coatings are found to have high cover ratio and no cracks are found by atomic force microscopes (AFM) and scanning electron microscopy (SEM). The main elements of the conversion coatings are Mg, Al, O, P and C by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The chemical state of the elements in the coatings was also investigated by Fourier transform infrared spectroscopy (FTIR). AES depth profile analysis suggests that the thickness of the conversion coating is about 340 nm. The corrosion resistance of the coatings was evaluated by polarization curves. The results indicate that the corrosion resistance for the conversion coated AZ91D magnesium alloys in 3.5% NaCl solution increases markedly. The mechanisms of corrosion resistance and coatings formation are also discussed.

  2. Optimization of Oxidation Temperature for Commercially Pure Titanium to Achieve Improved Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Bansal, Rajesh; Singh, J. K.; Singh, Vakil; Singh, D. D. N.; Das, Parimal

    2017-02-01

    Thermal oxidation of commercially pure titanium (cp-Ti) was carried out at different temperatures, ranging from 200 to 900 °C to achieve optimum corrosion resistance of the thermally treated surface in simulated body fluid. Scanning electron microscopy, x-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy techniques were used to characterize the oxides and assess their protective properties exposed in the test electrolyte. Maximum resistance toward corrosion was observed for samples oxidized at 500 °C. This was attributed to the formation of a composite layer of oxides at this temperature comprising Ti2O3 (titanium sesquioxide), anatase and rutile phases of TiO2 on the surface of cp-Ti. Formation of an intact and pore-free oxide-substrate interface also improved its corrosion resistance.

  3. Corrosion resistance of Si–Al-bearing ultrafine-grained weathering steel

    PubMed Central

    Nishimura, Toshiyasu

    2008-01-01

    In the Ultra-steel project at the National Institute for Materials Science (NIMS), which run from 1996 to 2005, high-Si–Al-content ultrafine-grained (UFG) weathering steel was developed by grain refinement and weathering guidance. It was found that this steel has excellent strength, toughness and corrosion resistance. Samples were prepared by multi pass warm rolling at temperatures between 773 and 873 K. The grain size of steel rolled at 873 K was about 1 μ m, and the tensile strength (TS) and elongation (EL) had excellent values of 800 MPa and 20%, respectively. In general, steels with high Si and Al contents exhibit inferior toughness to carbon steel (SM); however, the toughness of the developed sample was markedly improved by grain refinement. Cyclic corrosion tests in the presence of chloride ions confirmed that the developed steel exhibited excellent corrosion resistance, superior to that of SM. Electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) analyses showed that Si and Al mainly exist in the inner rust layer. Si and Al were identified as existing in the Si2 + and Al3 + states in the nanoscale complex oxides constituting the inner rust layer. Electrochemical impedance spectroscopy(EIS) measurement showed that the corrosion reaction resistance (Rt) of the developed steel was much greater than that of SM. In the developed steel, the nanoscale complex oxides were formed in the inner rust layer, which increased Rt, and resulted in the excellent corrosion resistance. PMID:27877923

  4. Applications in the Nuclear Industry for Corrosion-Resistant Amorphous-Metal Thermal-Spray Coatings

    SciTech Connect

    Farmer, J; Choi, J

    2007-07-18

    Amorphous metal and ceramic thermal spray coatings have been developed that can be used to enhance the corrosion resistance of containers for the transportation, aging and disposal of spent nuclear fuel and high-level radioactive wastes. Fe-based amorphous metal formulations with chromium, molybdenum and tungsten have shown the corrosion resistance believed to be necessary for such applications. Rare earth additions enable very low critical cooling rates to be achieved. The boron content of these materials, and their stability at high neutron doses, enable them to serve as high efficiency neutron absorbers for criticality control. Ceramic coatings may provide even greater corrosion resistance for container applications, though the boron-containing amorphous metals are still favored for criticality control applications. These amorphous metal and ceramic materials have been produced as gas atomized powders and applied as near full density, non-porous coatings with the high-velocity oxy-fuel process. This paper summarizes the performance of these coatings as corrosion-resistant barriers, and as neutron absorbers. Relevant corrosion models are also discussed, as well as a cost model to quantify the economic benefits possible with these new materials.

  5. Corrosion resistance of Si-Al-bearing ultrafine-grained weathering steel.

    PubMed

    Nishimura, Toshiyasu

    2008-01-01

    In the Ultra-steel project at the National Institute for Materials Science (NIMS), which run from 1996 to 2005, high-Si-Al-content ultrafine-grained (UFG) weathering steel was developed by grain refinement and weathering guidance. It was found that this steel has excellent strength, toughness and corrosion resistance. Samples were prepared by multi pass warm rolling at temperatures between 773 and 873 K. The grain size of steel rolled at 873 K was about 1 μ m, and the tensile strength (TS) and elongation (EL) had excellent values of 800 MPa and 20%, respectively. In general, steels with high Si and Al contents exhibit inferior toughness to carbon steel (SM); however, the toughness of the developed sample was markedly improved by grain refinement. Cyclic corrosion tests in the presence of chloride ions confirmed that the developed steel exhibited excellent corrosion resistance, superior to that of SM. Electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) analyses showed that Si and Al mainly exist in the inner rust layer. Si and Al were identified as existing in the Si(2 +) and Al(3 +) states in the nanoscale complex oxides constituting the inner rust layer. Electrochemical impedance spectroscopy(EIS) measurement showed that the corrosion reaction resistance (Rt) of the developed steel was much greater than that of SM. In the developed steel, the nanoscale complex oxides were formed in the inner rust layer, which increased Rt, and resulted in the excellent corrosion resistance.

  6. Enhanced High Temperature Corrosion Resistance in Advanced Fossil Energy Systems by Nano-Passive Layer Formation

    SciTech Connect

    Arnold R. Marder

    2007-06-14

    Due to their excellent corrosion resistance, iron aluminum alloys are currently being considered for use as weld claddings in fossil fuel fired power plants. The susceptibility to hydrogen cracking of these alloys at higher aluminum concentrations has highlighted the need for research into the effect of chromium additions on the corrosion resistance of lower aluminum alloys. In the present work, three iron aluminum alloys were exposed to simulated coal combustion environments at 500 C and 700 C for both short (100 hours) and long (5,000 hours) isothermal durations. Scanning electron microscopy was used to analyze the corrosion products. All alloys exhibited excellent corrosion resistance in the short term tests. For longer exposures, increasing the aluminum concentration was beneficial to the corrosion resistance. The addition of chromium to the binary iron aluminum alloy prevented the formation iron sulfide and resulted in lower corrosion kinetics. A classification of the corrosion products that developed on these alloys is presented. Scanning transmission electron microscopy (STEM) of the as-corroded coupons revealed that chromium was able to form chromium sulfides only on the higher aluminum alloy, thereby preventing the formation of deleterious iron sulfides. When the aluminum concentration was too low to permit selective oxidation of only aluminum (upon initial exposure to the corrosion environment), the formation of chromium oxide alongside the aluminum oxide led to depletion of chromium beneath the oxide layer. Upon penetration of sulfur through the oxide into this depletion layer, iron sulfides (rather than chromium sulfides) were found to form on the low aluminum alloy. Thus, it was found in this work that the role of chromium on alloy corrosion resistance was strongly effected by the aluminum concentration of the alloy. STEM analysis also revealed the encapsulation of external iron sulfide products with a thin layer of aluminum oxide, which may provide a

  7. Resistance of nitrogen-containing stainless alloys to corrosion in chloride media

    SciTech Connect

    Bandy, R.; van Rooyen, D.

    1982-10-08

    The pitting resistance of a series of experimental stainless steels with varying amounts of nickel, chromium, molybdenum, manganese and nitrogen and a number of commercial stainless steels and nickel based alloys has been studied in highly concentrated chloride media. The results show that nitrogen enhancer the pitting resistance of stainless steel and exceptional corrosion resistance is achieved with high levels of nitrogen in combination with suitable amounts of molybdenum and chromium.

  8. Resistance of nitrogen-containing stainless alloys to corrosion in chloride media

    SciTech Connect

    Bandy, R.; van Rooyen, D.

    1982-01-01

    The pitting resistance of a series of experimental stainless steels with varying amounts of nickel, chromium, molybdenum, manganese and nitrogen and a number of commercial stainless steels and nickel based alloys has been studied in highly concentrated chloride media. The results show that nitrogen enhances the pitting resistance of stainless steel and exceptional corrosion resistance is achieved with high levels of nitrogen in combination with suitable amounts of molybdenum and chromium.

  9. Corrosion resistance and electrochemical potentiokinetic reactivation testing of some iron-base hardfacing alloys

    SciTech Connect

    Cockeram, B.V.

    1999-11-01

    Hardfacing alloys are weld deposited on a base material to provide a wear resistant surface. Commercially available iron-base hardfacing alloys are being evaluated for replacement of cobalt-base alloys to reduce nuclear plant activation levels. Corrosion testing was used to evaluate the corrosion resistance of several iron-base hardfacing alloys in highly oxygenated environments. The corrosion test results indicate that iron-base hardfacing alloys in the as-deposited condition have acceptable corrosion resistance when the chromium to carbon ratio is greater than 4. Tristelle 5183, with a high niobium (stabilizer) content, did not follow this trend due to precipitation of niobium-rich carbides instead of chromium-rich carbides. This result indicates that iron-base hardfacing alloys containing high stabilizer contents may possess good corrosion resistance with Cr:C < 4. NOREM 02, NOREM 01, and NoCo-M2 hardfacing alloys had acceptable corrosion resistance in the as-deposited and 885 C/4 hour heat treated condition, but rusting from sensitization was observed in the 621 C/6 hour heat treated condition. The feasibility of using an Electrochemical Potentiokinetic Reactivation (EPR) test method, such as used for stainless steel, to detect sensitization in iron-base hardfacing alloys was evaluated. A single loop-EPR method was found to provide a more consistent measurement of sensitization than a double loop-EPR method. The high carbon content that is needed for a wear resistant hardfacing alloy produces a high volume fraction of chromium-rich carbides that are attacked during EPR testing. This results in inherently lower sensitivity for detection of a sensitized iron-base hardfacing alloy than stainless steel using conventional EPR test methods.

  10. Influence of alloying elements on corrosion resistance of low alloy steels in marine environment

    SciTech Connect

    Wei, F.I.

    1995-09-01

    Most area of the earth is ocean. Therefore, exploitation of marine resources and utilization of marine space rapidly increase in recent years. Most of marine structures, such as wharfs, oil drilling platforms, coastal bridges, airports, etc. are mainly constructed by steel. It is therefore very important to develop marine corrosion resistant steels that do not require protection and are inexpensive. In this study, a series of low alloy steels were prepared by the method of experimental design as well as conventional design to study the effects of alloying elements on the marine corrosion resistance, under consideration of the requirement of mechanical properties. All steels were cyclically dipped to synthetic sea water in the laboratory for 7 weeks or exposed in the Taichung Harbor for more than 4 years. Both test results show similar tendency of the effects of alloying elements, but the effects of fouling on pitting were only observed in the latter. Addition of phosphorus and copper can improve the general corrosion resistance in atmospheric splash zone and titanium has the same effect in sea water. Molybdenum can improve the general corrosion resistance in both splash and tidal zones and pitting resistance in tidal and submerged zones. Due to enrichment of the alloying elements in the rust resulting in development of inner dense rust layer and change of rust composition, the anti-corrosion ability of most designed steels can be enhanced in marine environment. In addition, the corrosion resistance of most tested steels is superior to plain carbon steel (A-36) and weathering steel (Acr-Ten A) in Taichung Harbor.

  11. Corrosion resistance of ceramic refractories to simulated waste glasses at high temperature

    SciTech Connect

    Xing, S.B.; Lin, Y.; Mohr, R.K.; Pegg, I.L.

    1996-08-01

    In many vitrification processes, refractory materials are used to contain the waste glass melt. The corrosive nature of the high-temperature melt consumes the waste feed materials but also limits refractory life. As vitrification is applied to more diverse waste streams, and particularly in higher-temperature applications, increasingly severe demands are placed on the refractory materials. A variety of potential refractory materials including Fused-cast AZS, Monofrax K3, Monofrax E, and the Corhart refractories ER1195, ER2161, C1215, C1215Z, Rechrome, and T1186, were subjected to corrosion testing at 1,450 C using the ASTM C-621 procedure. A series of simulated waste glasses was used which included F, Cl, S, Cu, Zn, Pb; these minor components were found to cause significant, and in some cases drastic, increases in corrosion rates. The corrosion tests were conducted over a range of time intervals extending to 144 hrs in order to investigate the kinetics of the corrosion processes. The change of the concentrations of constituents in the glass was monitored by compositional analysis of glass samples and correlated to the observed extent of corrosion; typically, components of the material under test increase with time while key minor components, such as Co and Pb, decrease. The rate of corrosion of high-zirconia refractories was slowed considerably by adding zirconia to the waste glass composition; this has the added benefit of improving the aqueous leach resistance of the waste form that is produced.

  12. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-07-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  13. Prediction of Corrosion Resistance of Concrete Containing Natural Pozzolan from Compressive Strength

    NASA Astrophysics Data System (ADS)

    al-Swaidani, A. M.; Ismat, R.; Diyab, M. E.; Aliyan, S. D.

    2015-11-01

    A lot of Reinforced Concrete (RC) structures in Syria have suffered from reinforcement corrosion which shortened significantly their service lives. Probably, one of the most effective approaches to make concrete structures more durable and concrete industry on the whole - more sustainable is to substitute pozzolan for a portion of Portland cement (PC). Syria is relatively rich in natural pozzolan. In the study, in order to predict the corrosion resistance from compressive strength, concrete specimens were produced with seven cement types: one plain Portland cement (control) and six natural pozzolan-based cements with replacement levels ranging from 10 to 35%. The development of the compressive strengths of concrete cube specimens with curing time has been investigated. Chloride penetrability has also been evaluated for all concrete mixes after three curing times of 7, 28 and 90 days. The effect on resistance of concrete against damage caused by corrosion of the embedded reinforcing steel has been investigated using an accelerated corrosion test by impressing a constant anodic potential for 7, 28 and 90 days curing. Test results have been statistically analysed and correlation equations relating compressive strength and corrosion performance have been developed. Significant correlations have been noted between the compressive strength and both rapid chloride penetrability and corrosion initiation times. So, this prediction could be reliable in concrete mix design when using natural pozzolan as cement replacement.

  14. Bacterial exopolysaccharides for corrosion resistance on low carbon steel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corrosion is a global issue that affects safety and economics. There is an increasing demand for bio-based polymers for industrial applications and production of polymers by micro-organisms is especially attractive. This work reports on the electrochemical and physical properties of exopolysaccharid...

  15. NANOSCALE BOEHMITE FILLER FOR CORROSION AND WEAR RESISTANT POLYPHENYLENESULFIDE COATINGS.

    SciTech Connect

    SUGAMA,T.

    2003-06-26

    The authors evaluated the usefulness of nanoscale boehmite crystals as a filler for anti-wear and anti-corrosion polyphenylenesulfide (PPS) coatings exposed to a very harsh, 300 C corrosive geothermal environment. The boehmite fillers dispersed uniformly into the PPS coating, conferring two advanced properties: First, they reduced markedly the rate of blasting wear; second, they increased the PPS's glass transition temperature and thermal decomposition temperature. The wear rate of PPS surfaces was reduced three times when 5wt% boehmite was incorporated into the PPS. During exposure for 15 days at 300 C, the PPS underwent hydrothermal oxidation, leading to the substitution of sulfide linkages by the sulfite linkages. However, such molecular alteration did not significantly diminish the ability of the coating to protect carbon steel against corrosion. In fact, PPS coating filled with boehmite of {le} 5wt% adequately mitigated its corrosion in brine at 300 C. One concern in using this filler was that it absorbs brine. Thus, adding an excess amount of boehmite was detrimental to achieving the maximum protection afforded by the coatings.

  16. Modification of aluminide coating with yttrium for improved resistance to corrosive erosion

    SciTech Connect

    Zhang, T.; Luo, Y.; Li, D.Y.

    1999-12-01

    Aluminide coatings on a mild steel substrate were modified by using an oxygen-active element, yttrium, for improved resistance to corrosive erosion. The performance of the yttrium-containing coating during the following three erosion conditions was evaluated: dry sand erosion at different temperatures, erosion in a dilute NaCl slurry containing 30% silica sand, and erosion in a dilute H{sub 2}SO{sub 4} slurry containing 30% silica sand. Results of the study demonstrated that yttrium significantly improved the resistance of the aluminide coating to both corrosive erosion and dry sand erosion.

  17. Corrosion Resistance of 304L SS Spray Coated with Zirconia Nanoparticles

    NASA Astrophysics Data System (ADS)

    Maheswari, A. Uma; Sivakumar, M.; Indhumathi, N.; Mohan, Sreedevi R.

    2016-09-01

    Influence of substrate temperature on corrosion (in 3.5% NaCl) and wear resistance of nanostructured zirconia thin film coated 304L SS substrates are studied by electrochemical and nano-indentation methods. This analysis shows 304L SS substrate spray coated with nanostructured zirconia at substrate temperature closer to the boiling point of the spray solvent ethanol exhibited good corrosion and wear resistance behaviour. This is because of the compressive stress developed during film fabrication at lower substrate temperature (∼50 °C) and hence constrains the indentation plasticity, which leads to higher indentation load than the bare 304L SS.

  18. Protection of NdFeB magnets by corrosion resistance phytic acid conversion film

    NASA Astrophysics Data System (ADS)

    Nan, Haiyang; Zhu, Liqun; Liu, Huicong; Li, Weiping

    2015-11-01

    Phytic acid conversion film was prepared on NdFeB magnets by dipping the NdFeB into phytic acid solution. The morphology, composition, structure and corrosion resistance of the film were systematically investigated. The results showed that the phytic acid film was effective in improving the corrosion resistance of NdFeB magnets. XRD, TEM and FT-IR analyses revealed that the film was amorphous and had a strong peak of phosphate radical (PO43-). The formation mechanism of the film was also explored by XPS and the potential of zero charge (Epzc) measurement at the solution-metal interface.

  19. Effect of a secondary metallurgy technology on the types of forming nonmetallic inclusions and the corrosion resistance of steel

    NASA Astrophysics Data System (ADS)

    Dub, V. S.; Safronov, A. A.; Movchan, M. A.; Ioffe, A. V.; Tazetdinov, V. I.; Zhivykh, G. A.

    2016-12-01

    The effect of a secondary metallurgy technology on the metal quality during the production of lowcarbon corrosion-resistant steels is estimated. The content of a modifier introduced is found to principally influence the types of inclusions and, via them, the corrosion resistance of parts from the metal subjected to deep refining from sulfur and nonmetallic inclusions.

  20. 78 FR 55241 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-10

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...) is conducting an administrative review of the countervailing duty (CVD) order on corrosion-resistant.... SUPPLEMENTARY INFORMATION: Scope of the Order The merchandise covered by this Order \\2\\ is certain...

  1. 76 FR 4291 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Partial Rescission of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-25

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea... administrative review of the countervailing duty order on corrosion- resistant carbon steel flat products from... ] requests for administrative review and partial revocation of the countervailing duty order on...

  2. 77 FR 25141 - Corrosion-Resistant Carbon Steel Flat Products From Germany and South Korea: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-27

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From Germany and South Korea... of the antidumping duty (AD) orders on corrosion-resistant carbon steel flat products (CORE) from... Countervailing Duty Operations, Office 3, regarding ``Sunset Reviews of the Antidumping Duty Orders on...

  3. Influence of microstructure on the corrosion resistance of Fe-44Ni thin films

    NASA Astrophysics Data System (ADS)

    Lu, Lin; Liu, Tian-cheng; Li, Xiao-gang

    2016-06-01

    An Fe-44Ni nanocrystalline (NC) alloy thin film was prepared through electrodeposition. The relation between the microstructure and corrosion behavior of the NC film was investigated using electrochemical methods and chemical analysis approaches. The results show that the NC film is composed of a face-centered cubic phase (γ-(Fe,Ni)) and a body-centered cubic phase (α-(Fe,Ni)) when it is annealed at temperatures less than 400°C. The corrosion resistance increases with the increase in grain size, and the corresponding corrosion process is controlled by oxygen reduction. The NC films annealed at 500°C and 600°C do not exhibit the same pattern, although their grain sizes are considerably large. This result is attributed to the existence of an anodic phase, Fe0.947Ni0.054, in these films. Under this condition, the related corrosion process is synthetically controlled by anodic dissolution and depolarization.

  4. Thermomechanical Manipulation of Crack-Tip Stress Field for Resistance to Stress Corrosion Crack Propagation

    NASA Astrophysics Data System (ADS)

    Singh Raman, R. K.; Ibrahim, R. N.; Wu, F.; Rihan, R.

    2008-12-01

    Corrosion-assisted propagation of an existing crack is profoundly influenced by the stress intensity at the crack tip. This article presents the first results of thermomechanical conditioning (TMC) for local manipulation of material at and ahead of the crack tip, in an attempt to retard/stop crack propagation. Prenotched round tensile specimens of mild steel were subjected to rotating bending to generate a fatigue precrack, and then to apply localized thermomechanical conditioning. The threshold stress intensity factor ( K ISCC ) for stress corrosion cracking (SCC) of precracked specimens with and without TMC was determined in a caustic environment. Results suggest that TMC can increase K ISCC . Finite element analysis of the specimens suggests development of compressive stresses at and around the crack tip, which is expected to improve the resistance to stress corrosion crack propagation (since stress corrosion cracks can propagate only under tensile loading).

  5. Analysis of corrosion resistance behavior of inhibitors in concrete using electrochemical techniques

    NASA Astrophysics Data System (ADS)

    Song, Ha-Won; Saraswathy, Velu

    2006-08-01

    Reinforced concrete is one of the most durable and cost effective construction materials. However, in high chloride environments, it can suffer from corrosion due to chloride induced breakdown of the normal passive layer protecting the reinforcing steel bars inside concrete. One means of protecting embedded steel reinforcement from chloride induced corrosion is the addition of corrosion inhibiting admixtures. In the present investigation, various inhibitors such as sodium nitrite, zinc oxide, mono ethanol amine, diethanolamine, and triethanol amine have been used in concrete in different percentages. Their effectiveness was then studied using various electrochemical techniques such as rapid chloride ion penetration test, open circuit potential measurement, electrochemical impedance measurement, potentiodynamic polarization measurement, and gravimetric weight loss measurement. The results thus obtained indicate that the addition of inhibitors enhances the corrosion resistance properties.

  6. Influence of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel welding joints

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiqiang; Jing, Hongyang; Xu, Lianyong; Han, Yongdian; Zhao, Lei; Zhang, Jianli

    2017-02-01

    The influences of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel joints welded by gas tungsten arc welding (GTAW) and flux-cored arc welding (FCAW) with different shielding gas compositions were studied by optical microscopy, electron backscatter diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron probe microanalysis, and potentiostatic and potentiodynamic polarization methods The adding 2% N2 in shielding gas facilitated primary austenite formation in GTAW weld metal (WM) and suppressed Cr2N precipitation in GTAW weld root. In the HAZ, the banded microstructure disappeared while the coarse ferrite grains maintained same orientation as the banded ferrite in the BM. In the WM, the ferrite had one single orientation throughout a grain, whereas several families of austenite appeared. The austenite both in BM and WM enriched in Ni and nitro`gen, while Cr and Mo were concentrated in the ferrite and thus no element showed clear dendritic distribution in the WM (ER2209 and E2209T1). In addition, the secondary austenite had higher Ni content but lower Cr and Mo content than the primary austenite. The N2-supplemented shielding gas promoted nitrogen solid-solution in the primary and secondary austenite. Furthermore, the secondary austenite had relatively lower pitting resistance equivalent number (PREN) than the ferrite and primary austenite, thereby resulting in its preferential corrosion. The Cr2N precipitation led to relatively poor resistance to pitting corrosion in three HAZs and pure Ar shielding GTAW weld root. The N2-supplemented shielding gas improved pitting corrosion resistance of GTAW joint by increasing PREN of secondary austenite and suppressing Cr2N precipitation. In addition, the FCAW WM had much poorer resistance to pitting corrosion than the GTAW WM due to many O-Ti-Si-Mn inclusions. In the BM, since the austenite with lower PREN compared

  7. Hydroxyapatite/poly(epsilon-caprolactone) double coating on magnesium for enhanced corrosion resistance and coating flexibility.

    PubMed

    Jo, Ji-Hoon; Li, Yuanlong; Kim, Sae-Mi; Kim, Hyoun-Ee; Koh, Young-Hag

    2013-11-01

    Hydroxyapatite was deposited on pure magnesium (Mg) with a flexible poly(ε-caprolactone) interlayer to reduce the corrosion rate of Mg and enhance coating flexibility. The poly(ε-caprolactone) interlayer was uniformly coated on Mg by a spraying method, followed by hydroxyapatite deposition on the poly(ε-caprolactone) using an aerosol deposition method. In scanning electron microscopy observations, inorganic/organic composite-like structure was observed between the hydroxyapatite and poly(ε-caprolactone) layers, resulting from the collisions of hydroxyapatite particles into the poly(ε-caprolactone) matrix at the initial stage of the aerosol deposition. The corrosion resistance of the coated Mg was examined using potentiodynamic polarization tests. The hydroxyapatite/poly(ε-caprolactone) double coating remarkably improved the corrosion resistance of Mg in Hank's solution. In the in vitro cell tests, the coated Mg showed better cell adhesion compared with the bare Mg due to the reduced corrosion rate and enhanced biocompatibility. The stability and flexibility of hydroxyapatite/poly(ε-caprolactone) double coating was investigated by scanning electron microscopy inspections after the coated Mg was deformed. The hydroxyapatite coating on the poly(ε-caprolactone) interlayer revealed enhanced coating stability and flexibility without cracking or delamination during bending and stretching compared with the hydroxyapatite single coating. These results demonstrated that the hydroxyapatite/poly(ε-caprolactone) double coating significantly improved the surface corrosion resistance of Mg and enhanced coating flexibility for use of Mg as a biodegradable implant.

  8. Electrochemical study of resistance to localized corrosion of stainless steels for biomaterial applications

    SciTech Connect

    Pan, J.; Karlen, C.; Ulfvin, C.

    2000-03-01

    Sandvik Bioline High-N and 316 LVM are two austenitic stainless steels especially developed for biomaterial applications. Their resistance to localized corrosion was investigated by electrochemical methods including cyclic potentiodynamic polarization and potentiostatic polarization measurements in a phosphate-buffered saline solution and in a simulated crevice solution, i.e., designed for crevice corrosion testing. Sandvik SAF 2507 (a high-performance super duplex stainless steel) was included in the tests as a reference material High-N, higher alloyed than 316 LVM, demonstrated excellent resistance to pitting initiation and a strong tendency to repassivation. High-N proved to have an equivalent or even higher resistance to localized corrosion than SAF 2507. The latter is known for its impressive corrosion properties, particularly in chloride containing environments. While 316 LVM may run the risk of crevice corrosion in implant applications, the risk seems negligible for High-N. In view of the fact that also the mechanical properties are superior to those of 316 LVM, High-N is a very attractive implant material.

  9. Enhanced antibacterial properties, biocompatibility, and corrosion resistance of degradable Mg-Nd-Zn-Zr alloy.

    PubMed

    Qin, Hui; Zhao, Yaochao; An, Zhiquan; Cheng, Mengqi; Wang, Qi; Cheng, Tao; Wang, Qiaojie; Wang, Jiaxing; Jiang, Yao; Zhang, Xianlong; Yuan, Guangyin

    2015-06-01

    Magnesium (Mg), a potential biodegradable material, has recently received increasing attention due to its unique antibacterial property. However, rapid corrosion in the physiological environment and potential toxicity limit clinical applications. In order to improve the corrosion resistance meanwhile not compromise the antibacterial activity, a novel Mg alloy, Mg-Nd-Zn-Zr (Hereafter, denoted as JDBM), is fabricated by alloying with neodymium (Nd), zinc (Zn), zirconium (Zr). pH value, Mg ion concentration, corrosion rate and electrochemical test show that the corrosion resistance of JDBM is enhanced. A systematic investigation of the in vitro and in vivo antibacterial capability of JDBM is performed. The results of microbiological counting, CLSM, SEM in vitro, and microbiological cultures, histopathology in vivo consistently show JDBM enhanced the antibacterial activity. In addition, the significantly improved cytocompatibility is observed from JDBM. The results suggest that JDBM effectively enhances the corrosion resistance, biocompatibility and antimicrobial properties of Mg by alloying with the proper amount of Zn, Zr and Nd.

  10. Corrosion resistance of three orthodontic brackets: a comparative study of three fluoride mouthwashes.

    PubMed

    Schiff, Nicolas; Dalard, Francis; Lissac, Michèle; Morgon, Laurent; Grosgogeat, Brigitte

    2005-12-01

    In the present study, three types of orthodontic brackets were investigated: cobalt-chromium (CoCr), iron-chromium-nickel (FeCrNi) and titanium (Ti) based. Their corrosion resistance was compared with that of platinum (Pt), which was chosen as the reference material because of its excellent electrochemical properties. The test solutions were Elmex, Meridol and Acorea fluoride mouthwashes. Fusayama Meyer artificial saliva was used as the reference solution. The corrosion resistance of the different brackets in the three mouthwashes was assessed electrochemically to determine the corrosion potential and corrosion current density, and polarization resistance values were then calculated. A scanning electron microscopic (SEM) study and an analysis of released metal ions confirmed the electrochemical studies. The results showed that the bracket materials could be divided into two groups: Ti and FeCrNi in one, and CoCr, which has properties close to those of Pt, in the other. Similarly, two groups of electrolytes were identified: Elmex and Acorea mouthwashes in one group, and Meridol mouthwash in the second group. The results indicate that because of the risk of corrosion Meridol mouthwash should not be prescribed for patients wearing Ti or FeCrNi-based orthodontic brackets.

  11. Study on possibility for the improvement of corrosion resistance of metals using laser-formed oxide surface structure

    NASA Astrophysics Data System (ADS)

    Ruzankina, J. S.; Vasiliev, O. S.

    2016-08-01

    The laser processes of oxidation are currently known and used extensively, in particular, to improve corrosion resistance of metals possessing certain properties and composition. In this regard, actuality is the methods of laser oxidation of metals and the determination of their modes of treatment in each specific case. Increase of corrosion resistance ST20 can carried out with the formation on the surface oxide films, as well as by reducing surface roughness. Studied various modes of processing of the steel surface. Corrosion resistance investigated for protecting a metal. Defocusing the beam to allow the surface treatment of a wide beam in the low temperature mode of processing. For further study of the irradiated surface on the corrosion resistance was conducted by chemical treatment in acid. Estimated phase composition of films formed under laser treatment simulated in the program astics. The study to increase the corrosion resistance of steel and titanium, have shown that under the chosen methods of processing of materials degradation observed.

  12. Corrosion-resistant antifretting coating for the protection of blade locking pieces in GTE compressors and fans

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.; Gorlov, D. S.; Egorova, L. P.; Bulavintseva, E. E.

    2014-09-01

    The properties of a corrosion-resistant antifretting coating on EP866Sh steel and VT8M-1 titanium alloy samples are studied. The results of corrosion resistance, heat resistance, fretting resistance, long-term strength, and high-cycle fatigue tests and the results of physical metallurgy and metallographic investigations of the samples with the coating before and after the tests are presented.

  13. Variation in corrosion resistance of nickel-titanium wires from different manufacturers.

    PubMed

    Huang, Her-Hsiung

    2005-07-01

    Nickel-titanium (NiTi) wires produced by various manufacturers may have different corrosion resistance in acidic oral environments. The purpose of this study was to investigate the variation during in vitro corrosion resistance of commercial NiTi dental orthodontic wires from different manufacturers using the fast electrochemical technique. The linear polarization test was used to evaluate the corrosion resistance, in terms of polarization resistance (Rp), of as-received commercial NiTi wires in acidic artificial saliva at 37 degrees C. One-way analysis of variance was used to analyze Rp with the wire manufacturer as the variable factor. Atomic force microscopy was used to analyze the three-dimensional surface topography and roughness (Ra). Electron spectroscopy for chemical analysis was used to identify the chemical structure of the passive film on the NiTi wires. The results showed that NiTi wires from different manufacturers had a statistically significant difference in Rp (P < .001). Different surface topography was present among the tested NiTi wires, whereas the same surface chemical structure was observed for the tested NiTi wires. The surface roughness of the commercial NiTi wires with similar surface chemical structure does not correspond with the difference in corrosion resistance.

  14. A new method to improve the corrosion resistance of titanium for hydrometallurgical applications

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Alfantazi, Akram; Asselin, Edouard

    2015-03-01

    The main objective of the present work was to develop a method to fabricate titanium oxide films with high corrosion resistance by controlled chemical oxidation with H2O2 solutions at 90 °C. The prepared chemically oxidized films (COFs) were characterized by X-ray diffraction (XRD) measurements and found to be a mixture of anatase and rutile or pure rutile, depending mainly on the presence of Cl- and SO42- in H2O2 solutions. XRD results indicated that the addition of SO42- ions promoted the formation of anatase; while the addition of Cl- ions favored the formation of rutile. Linear polarization resistance and electrochemical impedance spectroscopy measurements were used to evaluate the corrosion resistance of the as grown COFs for hydrometallurgical applications. Results verified that chemical oxidation with H2O2 solutions is capable of improving the corrosion resistance of Ti for hydrometallurgical applications. Chemical oxidation with 2 M H2O2/0.1 M HCl solution led to the best improvement of the corrosion resistance of Ti.

  15. Reduced platelet adhesion and improved corrosion resistance of superhydrophobic TiO₂-nanotube-coated 316L stainless steel.

    PubMed

    Huang, Qiaoling; Yang, Yun; Hu, Ronggang; Lin, Changjian; Sun, Lan; Vogler, Erwin A

    2015-01-01

    Superhydrophilic and superhydrophobic TiO2 nanotube (TNT) arrays were fabricated on 316L stainless steel (SS) to improve corrosion resistance and hemocompatibility of SS. Vertically-aligned superhydrophilic amorphous TNTs were fabricated on SS by electrochemical anodization of Ti films deposited on SS. Calcination was carried out to induce anatase phase (superhydrophilic), and fluorosilanization was used to convert superhydrophilicity to superhydrophobicity. The morphology, structure and surface wettability of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and contact angle goniometry. The effects of surface wettability on corrosion resistance and platelet adhesion were investigated. The results showed that crystalline phase (anatase vs. amorphous) and wettability strongly affected corrosion resistance and platelet adhesion. The superhydrophilic amorphous TNTs failed to protect SS from corrosion whereas superhydrophobic amorphous TNTs slightly improved corrosion resistance of SS. Both superhydrophilic and superhydrophobic anatase TNTs significantly improved corrosion resistance of SS. The superhydrophilic amorphous TNTs minimized platelet adhesion and activation whereas superhydrophilic anatase TNTs activated the formation of fibrin network. On the contrary, both superhydrophobic TNTs (superhydrophobic amorphous TNTs and superhydrophobic anatase TNTs) reduced platelet adhesion significantly and improved corrosion resistance regardless of crystalline phase. Superhydrophobic anatase TNTs coating on SS surface offers the opportunity for the application of SS as a promising permanent biomaterial in blood contacting biomedical devices, where both reducing platelets adhesion/activation and improving corrosion resistance can be effectively combined.

  16. Evaluation of the Comparative Corrosion Resistance Between AKOT Ti Alloy and Ti Gr 7 Alloy

    SciTech Connect

    Lian, T

    2005-08-01

    In its current design, the drip shields for the high-level nuclear waste containers for the Yucca Mountain repository will be mainly made using Ti Gr 7 (R52400). Ti Gr 7 is a highly corrosion resistant alloy, especially because it contains 0.15% palladium (Pd). The goal of this study was to determine whether an AKOT low-Pd (0.01%) titanium alloy would have a similar corrosion resistance than the more expensive Ti Gr 7 in environments that could be related to the performance of the drip shield. The focus of this testing program was on the susceptibility of the alloys to localized corrosion. Therefore, only artificially creviced specimens were used.

  17. "A L C L A D" A New Corrosion Resistant Aluminum Product

    NASA Technical Reports Server (NTRS)

    Dix, E H , Jr

    1927-01-01

    Described here is a new corrosion resistant aluminum product which is markedly superior to the present strong alloys. Its use should result in greatly increased life of a structural part. Alclad is a heat-treated aluminum, copper, manganese, magnesium alloy that has the corrosion resistance of pure metal at the surface and the strength of the strong alloy underneath. Of particular importance is the thorough character of the union between the alloy and the pure aluminum. Preliminary results of salt spray tests (24 weeks of exposure) show changes in tensile strength and elongation of Alclad 17ST, when any occurred, to be so small as to be well within the limits of experimental error. Some surface corrosion of the pure metal had taken place, but not enough to cause the specimens to break through those areas.

  18. Novel Application of ZSM-5 Zeolite: Corrosion-Resistant Coating in Chemical Process Industry

    NASA Astrophysics Data System (ADS)

    Pande, H. B.; Parikh, P. A.

    2013-01-01

    As-synthesized zeolite ZSM-5 containing the structure-directing agent, tetrapropyl ammonium bromide, when used as a coating material on mild steel substrate material, has been found to offer a promising corrosion resisting results against HCl, HNO3, H3PO4, and H2SO4 of various concentrations at temperatures up to 60 °C under stagnant and stirred conditions. Stable and continuous coated layer is observed under the conditions studied in this work by weight loss and electrochemical methods. Encouraging results in terms of corrosion inhibition efficiency indicate high potential with zeolite (Si/Al ratio 25) material. Material costs compare favorably for zeolite coating against the conventionally used materials. Summarily, zeolite offers an environment-friendly and cost-effective alternate to the other toxic and carcinogenic materials as corrosion-resistant coating.

  19. Corrosion Resistant Magnesium-Based Materials for Naval Applications

    DTIC Science & Technology

    1985-04-01

    MARINE ATMOSPHERE AT NSWC, FT. LAUDERDALE, FLORIDA,. CORROSION TEST FACILITY .................... 13 5 PHASE DIAGRAMS OF MAGNESIUM- BERYLLIUM AND...aluminum components (p a 2.7 g/cc) must possess measurably better physical properties and comparable workability. Beryllium (p - 1.85 g/cc) was...dedicated special fabrication facilities are required for working with Beryllium because of its extreme toxicity it. handling and machining. The next

  20. Method for preparing corrosion-resistant ceramic shapes

    DOEpatents

    Arons, R.M.; Dusek, J.T.

    1979-12-07

    Ceramic shapes having impermeable tungsten coatings can be used for containing highly corrosive molten alloys and salts. The shapes are prepared by coating damp green ceramic shapes containing a small amount of yttria with a tungsten coating slip which has been adjusted to match the shrinkage rate of the green ceramic and which will fire to a theoretical density of at least 80% to provide an impermeable coating.

  1. Method for preparing corrosion-resistant ceramic shapes

    DOEpatents

    Arons, Richard M.; Dusek, Joseph T.

    1983-09-13

    Ceramic shapes having impermeable tungsten coatings can be used for containing highly corrosive molten alloys and salts. The shapes are prepared by coating damp green ceramic shapes containing a small amount of yttria with a tungsten coating slip which has been adjusted to match the shrinkage rate of the green ceramic and which will fire to a theoretical density of at least 80% to provide a impermeable coating.

  2. Iron-Based Amorphous-Metals: High-Performance Corrosion-Resistant Material (HPCRM) Development

    SciTech Connect

    Farmer, J C; Choi, J S; Saw, C; Haslam, J; Day, D; Hailey, P; Lian, T; Rebak, R; Perepezko, J; Payer, J; Branagan, D; Beardsley, B; D'Amato, A; Aprigliano, L

    2008-01-09

    An overview of the High-Performance Corrosion-Resistant Materials (HPCRM) Program, which was co-sponsored by the Defense Advanced Research Projects Agency (DARPA) Defense Sciences Office (DSO) and the United States Department of Energy (DOE) Office of Civilian and Radioactive Waste Management (OCRWM), is discussed. Programmatic investigations have included a broad range of topics: alloy design and composition; materials synthesis; thermal stability; corrosion resistance; environmental cracking; mechanical properties; damage tolerance; radiation effects; and important potential applications. Amorphous alloys identified as SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) and SAM1651 (Fe{sub 48}Mo{sub 14}Cr{sub 15}Y{sub 2}C{sub 15}B{sub 6}) have been produced as melt-spun ribbons, drop-cast ingots and thermal-spray coatings. Chromium (Cr), molybdenum (Mo) and tungsten (W) additions provided corrosion resistance, while boron (B) enabled glass formation. Earlier electrochemical studies of melt-spun ribbons and ingots of these amorphous alloys demonstrated outstanding passive film stability. More recently thermal-spray coatings of these amorphous alloys have been made and subjected to long-term salt-fog and immersion tests. Good corrosion resistance has been observed during salt-fog testing. Corrosion rates were measured in situ with linear polarization, while simultaneously monitoring the open-circuit corrosion potentials. Reasonably good performance was observed. The sensitivity of these measurements to electrolyte composition and temperature was determined. The high boron content of this particular amorphous metal makes this amorphous alloy an effective neutron absorber, and suitable for criticality control applications. In general, the corrosion resistance of such iron-based amorphous metals is maintained at operating temperatures up to the glass transition temperature. These materials are much harder than conventional

  3. Iron-Based Amorphous Metals:The High Performance Corrosion Resistant Materials(HPCRM) Program

    SciTech Connect

    Farmer, J

    2007-07-09

    An overview of the High-Performance Corrosion-Resistant Materials (HPCRM) Program, which was co-sponsored by the Defense Advanced Research Projects Agency (DARPA) Defense Sciences Office (DSO) and the United States Department of Energy (DOE) Office of Civilian and Radioactive Waste Management (OCRWM), is discussed. Programmatic investigations have included a broad range of topics: alloy design and composition; materials synthesis; thermal stability; corrosion resistance; environmental cracking; mechanical properties; damage tolerance; radiation effects; and important potential applications. Amorphous alloys identified as SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) and SAM1651 (Fe{sub 48}Mo{sub 14}Cr{sub 15}Y{sub 2}C{sub 15}B{sub 6}) have been produced as melt-spun ribbons, drop-cast ingots and thermal-spray coatings. Chromium (Cr), molybdenum (Mo) and tungsten (W) additions provided corrosion resistance, while boron (B) enabled glass formation. Earlier electrochemical studies of melt-spun ribbons and ingots of these amorphous alloys demonstrated outstanding passive film stability. More recently thermal-spray coatings of these amorphous alloys have been made and subjected to long-term salt-fog and immersion tests. Good corrosion resistance has been observed during salt-fog testing. Corrosion rates were measured in situ with linear polarization, while simultaneously monitoring the open-circuit corrosion potentials. Reasonably good performance was observed. The sensitivity of these measurements to electrolyte composition and temperature was determined. The high boron content of this particular amorphous metal makes this amorphous alloy an effective neutron absorber, and suitable for criticality control applications. In general, the corrosion resistance of such iron-based amorphous metals is maintained at operating temperatures up to the glass transition temperature. These materials are much harder than conventional

  4. Iron-Based Amorphous Metals: High-Performance Corrosion-Resistant Material Development

    NASA Astrophysics Data System (ADS)

    Farmer, Joseph; Choi, Jor-Shan; Saw, Cheng; Haslam, Jeffrey; Day, Dan; Hailey, Phillip; Lian, Tiangan; Rebak, Raul; Perepezko, John; Payer, Joe; Branagan, Daniel; Beardsley, Brad; D'Amato, Andy; Aprigliano, Lou

    2009-06-01

    An overview of the High-Performance Corrosion-Resistant Materials (HPCRM) Program, which was cosponsored by the Defense Advanced Research Projects Agency (DARPA) Defense Sciences Office (DSO) and the U.S. Department of Energy (DOE) Office of Civilian and Radioactive Waste Management (OCRWM), is discussed. Programmatic investigations have included a broad range of topics: alloy design and composition, materials synthesis, thermal stability, corrosion resistance, environmental cracking, mechanical properties, damage tolerance, radiation effects, and important potential applications. Amorphous alloys identified as SAM2X5 (Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4) and SAM1651 (Fe48Mo14Cr15Y2C15B6) have been produced as meltspun ribbons (MSRs), dropcast ingots, and thermal-spray coatings. Chromium (Cr), molybdenum (Mo), and tungsten (W) additions provided corrosion resistance, while boron (B) enabled glass formation. Earlier electrochemical studies of MSRs and ingots of these amorphous alloys demonstrated outstanding passive film stability. More recently, thermal-spray coatings of these amorphous alloys have been made and subjected to long-term salt-fog and immersion tests; good corrosion resistance has been observed during salt-fog testing. Corrosion rates were measured in situ with linear polarization, while the open-circuit corrosion potentials (OCPs) were simultaneously monitored; reasonably good performance was observed. The sensitivity of these measurements to electrolyte composition and temperature was determined. The high boron content of this particular amorphous metal makes this amorphous alloy an effective neutron absorber and suitable for criticality-control applications. In general, the corrosion resistance of such iron-based amorphous metals is maintained at operating temperatures up to the glass transition temperature. These materials are much harder than conventional stainless steel and Ni-based materials, and are proving to have excellent wear

  5. Evaluation of stainless steels for their resistance to intergranular corrosion

    NASA Astrophysics Data System (ADS)

    Korostelev, A. B.; Abramov, V. Ya.; Belous, V. N.

    1996-10-01

    Austenitic stainless steels are being considered as structural materials for first wall/blanket systems in the International Thermonuclear Reactor (ITER). The uniform corrosion of stainless steels in water is well known and is not a critical issue limiting its application for the ITER design. The sensitivity of austenitic steels to intergranular corrosion (IGC) can be estimated rather accurately by means of calculation methods, considering structure and chemical composition of steel. There is a maximum permissible carbon content level, at which sensitization of stainless steel is eliminated: K = Cr eff - αC eff, where α-thermodynamic coefficient, Cr eff-effective chromium content (regarding molybdenum influence) and C eff-effective carbon content (taking into account nickel and stabilizing elements). Corrosion tests for 16Cr11Ni3MoTi, 316L and 316LN steel specimens, irradiated up to 2 × 10 22 n/cm 2 fluence have proved the effectiveness of this calculation technique for determination of austenitic steels tendency to IGC. This method is directly applicable in austenitic stainless steel production and enables one to exclude complicated experiments on determination of stainless steel susceptibility to IGC.

  6. Corrosion-resistant steel fiber produced by the melt-extraction method and its use in refractories

    NASA Astrophysics Data System (ADS)

    Van I-Kho; Ven-Nen, Lyu

    1992-09-01

    Corrosion-resistant steel fiber produced by the melt-extraction method has distinct reinforcing properties, a high capacity to bond with a refractory, low net-cost, and economic production. The introduction of corrosion-resistant steel fibers in refractory articles and materials for concrete spraying improves their thermal stability and mechanical strength. The service life of refractory articles is increased as a result of an increase in resistance to failure and impact loads. Use of corrosion-resistant steel fibers contributes to significant material energy savings, and improves the productivity of furnaces and apparatus.

  7. Effect of internal nitriding on the fatigue strength of ferritic corrosion-resistant steel

    NASA Astrophysics Data System (ADS)

    Rogachev, S. O.; Nikulin, S. A.; Terent'ev, V. F.; Khatkevich, V. M.; Prosvirnin, D. V.; Savicheva, R. O.

    2015-04-01

    The effect of internal nitriding and subsequent annealing on the mechanical properties of ferritic corrosion-resistance 08Kh17T steel has been studied during static and cyclic loading. Nitriding was shown to increase the static and cyclic strength of ferritic steel substantially and to decrease its plasticity slightly. These changes are confirmed by results of fractographic studies.

  8. Corrosion-resistant fuel cladding allow for liquid metal fast breeder reactors

    DOEpatents

    Brehm, Jr., William F.; Colburn, Richard P.

    1982-01-01

    An aluminide coating for a fuel cladding tube for LMFBRs (liquid metal fast breeder reactors) such as those using liquid sodium as a heat transfer agent. The coating comprises a mixture of nickel-aluminum intermetallic phases and presents good corrosion resistance to liquid sodium at temperatures up to 700.degree. C. while additionally presenting a barrier to outward diffusion of .sup.54 Mn.

  9. In vitro corrosion resistance of porous NiTi intervertebral fusion devices

    NASA Astrophysics Data System (ADS)

    Schrooten, Jan; Assad, Michel; Van Humbeeck, Jan; Leroux, Michel A.

    2007-02-01

    Porous titanium-nickel (PTN) intervertebral fusion devices, produced by self-propagating high-temperature synthesis, represent an alternative to traditional long-term implants in the orthopaedic field. PTN promotes tissue ingrowth and has succeeded short-term and long-term biocompatibility in vivo testing. In this in vitro study, the PTN morphology was characterized using microfocus computer tomography (μCT) in order to calculate the active PTN surface. Potentiodynamic polarization testing was then performed to evaluate the in vitro corrosion resistance of PTN devices in Hanks' based salt solution. Direct coupling experiments of PTN with Ti6Al4V were also performed in order to establish the galvanic corrosion resistance of PTN intervertebral implants in the presence of potential Ti6Al4V supplemental fixation devices. Compared to the behaviour of other orthopaedic biomaterials and solid NiTi devices, PTN devices showed a level of corrosion resistance that is comparable to other NiTi devices and acceptable for the intended orthopaedic application. Further improvement of the corrosion resistance is still possible by specific electrochemical surface treatments.

  10. Impact of the nanostructuration on the corrosion resistance and hardness of irradiated 316 austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Hug, E.; Prasath Babu, R.; Monnet, I.; Etienne, A.; Moisy, F.; Pralong, V.; Enikeev, N.; Abramova, M.; Sauvage, X.; Radiguet, B.

    2017-01-01

    The influence of grain size and irradiation defects on the mechanical behavior and the corrosion resistance of a 316 stainless steel have been investigated. Nanostructured samples were obtained by severe plastic deformation using high pressure torsion. Both coarse grain and nanostructured samples were irradiated with 10 MeV 56Fe5+ ions. Microstructures were characterized using transmission electron microscopy and atom probe tomography. Surface mechanical properties were evaluated thanks to hardness measurements and the corrosion resistance was studied in chloride environment. Nanostructuration by high pressure torsion followed by annealing leads to enrichment in chromium at grain boundaries. However, irradiation of nanostructured samples implies a chromium depletion of the same order than depicted in coarse grain specimens but without metallurgical damage like segregated dislocation loops or clusters. Potentiodynamic polarization tests highlight a definitive deterioration of the corrosion resistance of coarse grain steel with irradiation. Downsizing the grain to a few hundred of nanometers enhances the corrosion resistance of irradiated samples, despite the fact that the hardness of nanocrystalline austenitic steel is only weakly affected by irradiation. These new experimental results are discussed in the basis of couplings between mechanical and electrical properties of the passivated layer thanks to impedance spectroscopy measurements, hardness properties of the surfaces and local microstructure evolutions.

  11. Oxidation and corrosion resistance of candidate Stirling engine heater-head-tube alloys

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Barrett, C. A.

    1984-01-01

    Sixteen candidate iron base Stirling engine heater head tube alloys are evaluated in a diesel fuel fired simulator materials test rig to determine their oxidation and corrosion resistance. Sheet specimens are tested at 820 C for 3500 hr in 5 hr heating cycles. Specific weight change data and an attack parameter are used to categorize the alloys into four groups; 10 alloys show excellent for good oxidation and corrosion resistance and six alloys exhibit poor or catastrophic resistance. Metallographic, X-ray, and electron microprobe analyses aid in further characterizing the oxidation and corrosion behavior of the alloys. Alloy compositions, expecially the reactive elements aluminum, titanium, and chromium, play a major role in the excellent oxidation and corrosion behavior of the alloys. The best oxidation resistance is associated with the formation of an iron nickel aluminum outer oxide scale, an intermediate oxide scale rich in chromium and titanium, and an aluminum outer oxide scale adjacent to the metallic substrate, which exhibits a zone of internal oxidation of aluminum and to some extent titanium.

  12. Relation Between Open Circuit Potential and Polarization Resistance with Rust and Corrosion Monitoring of Mild Steel

    NASA Astrophysics Data System (ADS)

    Choudhary, S.; Garg, A.; Mondal, K.

    2016-07-01

    The present work discusses continuous corrosion assessment from a unique correlation of open circuit potential (OCP) and linear polarization resistance with rust formation on mild steel after prolong exposure in 3.5% NaCl salt fog environment. The OCP measurement and linear polarization tests were carried out of the rusted samples only without the removal of rust. It also discusses the strong influence of the composition, fraction, and morphology of the rust layers with OCP and linear polarization resistance. The rust characterization was done after the measurement of OCP and linear polarization resistance of the rusted steel samples. Therefore, monitoring of both the OCP and linear polarization resistance of the rusted mild steels coupled with rust characterization could be used for easy and dynamic assessment of the nature of corrosion.

  13. Effects of Solution and Aging Treatments on Corrosion Resistance of As-cast 60NiTi Alloy

    NASA Astrophysics Data System (ADS)

    Qin, Qiuhui; Wen, Yuhua; Wang, Gaixia; Zhang, Lanhui

    2016-12-01

    60NiTi alloy has become a competitive candidate for bearing applications due to its shape memory effect, superelasticity, high strength, hardness, excellent abrasion resistance and corrosion resistance, etc. However, the relationship between its corrosion resistance and heat treatment is not clearly understood. Therefore, we used OM, XRD, SEM and EDS to study the evolution of microstructure in as-cast, solution-treated and aged 60NiTi alloy. Besides, the potentiodynamic polarization and salt spray test were used to compare corrosion resistance of 60NiTi alloy and 316 stainless steel and to study the effect of microstructures on corrosion resistance of 60NiTi alloy. The results show that the corrosion resistance of as-cast 60NiTi alloy is comparable to that of 316 stainless steel, but the corrosion resistance of solution-treated and aged 60NiTi alloys is much superior. The significantly reduced Ni3Ti phase after the solution and aging treatments is responsible for the remarkable improvement in the corrosion resistance of as-cast 60NiTi alloy.

  14. The intrinsically high pitting corrosion resistance of mechanically polished nitinol in simulated physiological solutions.

    PubMed

    Bai, Zhijun; Rotermund, Harm H

    2011-10-01

    Nitinol wires have been widely used in many biomedical applications, such as cardiovascular stent due to their superelasticity and shape memory effect. However, their corrosion properties and the related biocompatibility are not well understood, and the reported results are controversial. In this study, we evaluate the pitting corrosion property of nitinol, titanium, nickel, and 316L stainless steel (316LSS) wires with different surface roughnesses in a saline solution at 37 °C. The cyclic potentiodynamic polarization results show that mechanically polished nitinol and Ti wires are highly resistant to pitting corrosion, while Ni and 316LSS wires are susceptible to pitting corrosion. Electrochemical impedance spectroscopy is used to study the interface of oxide film/solution and all mechanically polished nitinol wires are covered by 2-3 nm thick films formed under open circuit potential. Furthermore, the electronic structures and semiconducting properties of passive films on nitinol, Ti and Ni wires are studied by Mott-Schottky analysis. Passive films formed on nitinol and Ti exhibit n-type semiconducting characteristics, whereas films on Ni show p-type semiconducting characteristics. Scanning Kelvin Microscopy is used to measure the surface potential difference between common inclusions from the nitinol matrix and the results indicate that the inclusions are more electrochemically noble than the nitinol matrix. Band energy theory is used to model the electrochemical interface between the passive films of nitinol and the solution under different applied potential conditions. A mechanism for the strong pitting corrosion resistance of nitinol in saline solution is proposed.

  15. Ceramic Coatings for Corrosion Resistant Nuclear Waste Container Evaluated in Simulated Ground Water at 90?C

    SciTech Connect

    Haslam, J J; Farmer, J C

    2004-03-31

    Ceramic materials have been considered as corrosion resistant coatings for nuclear waste containers. Their suitability can be derived from the fully oxidized state for selected metal oxides. Several types of ceramic coatings applied to plain carbon steel substrates by thermal spray techniques have been exposed to 90 C simulated ground water for nearly 6 years. In some cases no apparent macroscopic damage such as coating spallation was observed in coatings. Thermal spray processes examined in this work included plasma spray, High Velocity Oxy Fuel (HVOF), and Detonation Gun. Some thermal spray coatings have demonstrated superior corrosion protection for the plain carbon steel substrate. In particular the HVOF and Detonation Gun thermal spray processes produced coatings with low connected porosity, which limited the growth rate of corrosion products. It was also demonstrated that these coatings resisted spallation of the coating even when an intentional flaw (which allowed for corrosion of the carbon steel substrate underneath the ceramic coating) was placed in the coating. A model for prediction of the corrosion protection provided by ceramic coatings is presented. The model includes the effect of the morphology and amount of the porosity within the thermal spray coating and provides a prediction of the exposure time needed to produce a crack in the ceramic coating.

  16. The Application of Heat and Corrosion Resistant Phosphate Coatings Under Steam Pressure

    DTIC Science & Technology

    1974-03-01

    SUPPLEMENTARY NorEs 19. KEY ’WORDS (Continue on reverae aide if neceasary and Identify by block number) 1. Phosphate coatings 4 . Corrosion resistance 2...Manganese phosphate 5. Pressure Vessel 3 . Heat resistance 20. ABSTRACT (Continue on reveae aide it necesary and Identify by bloch number) Processing...2 Manganese Phosphate Coatings Applied in a 15 Conventional Bath with and without Mangan- ese Citrate 3 Me ganese Phosphate Coatings Applied in a 18

  17. Demonstration and Validation of Materials for Corrosion-Resistant Fencing and Guard Railings in Aggressive Climates

    DTIC Science & Technology

    2015-10-01

    Resistant Fencing and Guard Railings in Aggressive Climates Final Report on Project F09-AR02 Co ns tr uc tio n En gi ne er in g R es ea rc h La bo ra to...29 October 2015 Demonstration and Validation of Materials for Corrosion-Resistant Fencing and Guard Railings in Aggressive Climates Final Report...a cold marine climate . Researchers coordinated with Department of Public Works (DPW) and engineering of- fice personnel to select the specific

  18. Stress-corrosion resistant proppant for oil and gas wells

    SciTech Connect

    Khaund, A.K.

    1987-01-27

    This patent describes a proppant medium composed of spherical particles of a sintered composition of alumina, silica, and the impurities associated with bauxite, such impurities selected from the group consisting of alkali and alkaline earth, oxides, iron oxide, and titanium oxide. The improvement described here is wherein there is at least 15% silica in the composition and zirconium oxide is present in the ratio of between one part of zirconia per twenty parts of silica to one part of zirconia per six parts of silica by weight, the proppant spheres as fired, consisting essentially of mullite, alumina, and glass. The silica content in the weight ratio is calculated as SiO/sub 2/ combined in the mullite phase and SiO/sub 2/ in the glass phase, and zirconia content is calculated as ZrO/sub 2/ and is present in the glass phase.

  19. Influence of casting procedures on the corrosion resistance of clinical dental alloys containing palladium.

    PubMed

    Viennot, Stéphane; Lissac, Michèle; Malquarti, Guillaume; Dalard, Francis; Grosgogeat, Brigitte

    2006-05-01

    The aim of this study was to compare the in vitro corrosion resistance in artificial saliva of two palladium-silver alloys (a Pd-Ag (Pors on 4) and an Ag-Pd (Palliag LTG)), with and without casting defects; 1 nickel-chrome alloy and 1 high-gold alloy, cast under recommended conditions, served as controls. For each of the palladium-based alloys, three specimens corresponding to three different casting conditions were used: under recommended conditions, with the use of a graphite-containing investment and crucible, and by reusing the sprues and sprue button. The electrochemical tests were run in Fusayama-Meyer artificial saliva. The open-circuit potential was recorded in mV/SCE at t=24h. Then, potentiodynamic polarization was performed to measure the polarization resistance (R(p)) in kOmega cm(2) and the corrosion current (i(corr)) in microA cm(-2). Data were evaluated with one-way analysis of variance and multiple comparisons test (alpha=0.05). In addition, each specimen was examined by scanning electron microscopy. Compared to the control alloys, the electrochemical experiments in artificial saliva indicated satisfactory corrosion resistance for the Pd-Ag and Ag-Pd alloys; these results are related to their high noble metal content and stable substructure. The Pd-Ag alloy displayed superior electrochemical properties to those of the Ag-Pd alloy regardless of the casting condition. The use of the graphite-containing crucible and investment during the cast process did not dramatically reduce the corrosion resistance values, but the reuse of sprues and the sprue button did. The optimal corrosion resistance values were obtained for the alloys cast according to the recommended conditions.

  20. High-Temperature Ceramic Matrix Composite with High Corrosion Resistance

    DTIC Science & Technology

    2010-06-02

    composites of ZrB2- SiC system will be created, their structure and high-temperature mechanical and corrosion properties will be studied up to 1600 C. The...scale defects. As a result of Project fulfillment a new knowledge for structural state and properties of ceramic composites management techniques...Fragment of XRD pattern for molybdenum silicide . Fig. 2.5. XRD pattern for USS-22+ 2 vol.% TaB2 hot-pressed samples. Fig. 2.6. XRD pattern for USS-22

  1. Resistance of Silicon Nitride Turbine Components to Erosion and Hot Corrosion/oxidation Attack

    NASA Technical Reports Server (NTRS)

    Strangmen, Thomas E.; Fox, Dennis S.

    1994-01-01

    Silicon nitride turbine components are under intensive development by AlliedSignal to enable a new generation of higher power density auxiliary power systems. In order to be viable in the intended applications, silicon nitride turbine airfoils must be designed for survival in aggressive oxidizing combustion gas environments. Erosive and corrosive damage to ceramic airfoils from ingested sand and sea salt must be avoided. Recent engine test experience demonstrated that NT154 silicon nitride turbine vanes have exceptional resistance to sand erosion, relative to superalloys used in production engines. Similarly, NT154 silicon nitride has excellent resistance to oxidation in the temperature range of interest - up to 1400 C. Hot corrosion attack of superalloy gas turbine components is well documented. While hot corrosion from ingested sea salt will attack silicon nitride substantially less than the superalloys being replaced in initial engine applications, this degradation has the potential to limit component lives in advanced engine applications. Hot corrosion adversely affects the strength of silicon nitride in the 850 to 1300 C range. Since unacceptable reductions in strength must be rapidly identified and avoided, AlliedSignal and the NASA Lewis Research Center have pioneered the development of an environmental life prediction model for silicon nitride turbine components. Strength retention in flexure specimens following 1 to 3300 hour exposures to high temperature oxidation and hot corrosion has been measured and used to calibrate the life prediction model. Predicted component life is dependent upon engine design (stress, temperature, pressure, fuel/air ratio, gas velocity, and inlet air filtration), mission usage (fuel sulfur content, location (salt in air), and times at duty cycle power points), and material parameters. Preliminary analyses indicate that the hot corrosion resistance of NT154 silicon nitride is adequate for AlliedSignal's initial engine

  2. Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings.

    PubMed

    Eric Jones, John; Chen, Meng; Yu, Qingsong

    2014-10-01

    To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20-25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH₃/O₂ plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O- and N-contents on the surfaces were substantially increased after NH₃/O₂ plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH₃/O₂ plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream.

  3. Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings

    PubMed Central

    Jones, John Eric; Chen, Meng; Yu, Qingsong

    2015-01-01

    To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20–25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH3/O2 plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O-and N-contents on the surfaces were substantially increased after NH3/O2 plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH3/O2 plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electro-chemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream. PMID:24500866

  4. Microstructure Aspects of a Newly Developed, Low Cost, Corrosion-Resistant White Cast Iron

    NASA Astrophysics Data System (ADS)

    Sain, P. K.; Sharma, C. P.; Bhargava, A. K.

    2013-04-01

    The purpose of this work is to study the influence of heat treatment on the corrosion resistance of a newly developed white cast iron, basically suitable for corrosion- and wear-resistant applications, and to attain a microstructure that is most suitable from the corrosion resistance point of view. The composition was selected with an aim to have austenitic matrix both in as-cast and heat-treated conditions. The difference in electrochemical potential between austenite and carbide is less in comparison to that between austenite and graphite. Additionally, graphitic corrosion which is frequently encountered in gray cast irons is absent in white cast irons. These basic facts encouraged us to undertake this work. Optical metallography, hardness testing, X-ray diffractometry, and SEM-EDX techniques were employed to identify the phases present in the as-cast and heat-treated specimens of the investigated alloy and to correlate microstructure with corrosion resistance and hardness. Corrosion testing was carried out in 5 pct NaCl solution (approximate chloride content of sea water) using the weight loss method. In the investigated alloy, austenite was retained the in as-cast and heat-treated conditions. The same was confirmed by X-ray and EDX analysis. The stability and volume fraction of austenite increased with an increase of heat-treated temperature/time with a simultaneous decrease in the volume fraction of massive carbides. The decrease in volume fraction of massive carbides resulted in the availability of alloying elements. These alloying elements, on increasing the heat treatment temperature or increasing the soaking period at certain temperatures, get dissolved in austenite. As a consequence, austenite gets enriched as well as becomes more stable. On cooling from lower soaking period/temperature, enriched austenite decomposes to lesser enriched austenite and to a dispersed phase due to decreasing solid solubility of alloying elements with decreasing temperature

  5. Protection of 2024-T3 aluminium alloy by corrosion resistant phytic acid conversion coating

    NASA Astrophysics Data System (ADS)

    Shi, Hongwei; Han, En-Hou; Liu, Fuchun; Kallip, Silvar

    2013-09-01

    The corrosion protection properties of environmentally friendly phytic acid conversion coatings were studied on 2024-T3 aluminium alloy. The films were prepared under acidic conditions with various pH values and characterised by SEM, EDS, ATR-FTIR and electrochemical techniques. The results indicate that the conversion coatings obtained by immersing the alloy in phytic acid solutions at pH from 3 to 5.5 provide excellent corrosion resistance. ATR-FTIR confirms that the film is formed by deposition of reaction products between Al3+ and phosphate groups in phytic acid molecules. The conformation models of the deposition film are proposed.

  6. Multiscale Electrochemical Investigation of the Corrosion Resistance of Various Alloys Used in Dental Prostheses

    NASA Astrophysics Data System (ADS)

    Iacoban, Sorin; Mareci, Daniel; Bolat, Georgiana; Munteanu, Corneliu; Souto, Ricardo Manuel

    2015-04-01

    The electrochemical behavior of Ag-Pd (Paliag), Ni-Cr (Heraenium NA), and Co-Cr (Heraenium CE) alloys used in dental prosthetics construction of crowns and bridges was studied in 0.9 pct NaCl solution at 298 K (25 °C). The localized electrochemical characteristics related to corrosion resistance and eventual breakdown of the protecting oxide layers were investigated by scanning electrochemical microscopy (SECM), whereas potentiodynamic polarization and electrochemical impedance spectroscopy techniques were employed to establish oxide stability. When the corrosion resistance of the alloys was evaluated by means of the corrosion current value determined around their corresponding open circuit potential in 0.9 pct NaCl solution, good protection can be expected resulting from their spontaneous passivation (low current densities in the order of tenths of μA cm-2). The polarization resistance of all the samples increased with immersion time, in the sequence Ag-Pd < Heraenium NA < Heraenium CE. Yet, increased electrochemical activity was detected with SECM when the alloys were polarized at +0.40 V SCE, a value that may be eventually experienced in the human body. Although a passivation mechanism was still operating in the chromium-containing alloys, oxide dissolution and precipitation of corrosion products occurred on Ag-Pd instead.

  7. Effect of calcium-ion implantation on the corrosion resistance and biocompatibility of titanium.

    PubMed

    Krupa, D; Baszkiewicz, J; Kozubowski, J A; Barcz, A; Sobczak, J W; Bilińiski, A; Lewandowska-Szumieł, M D; Rajchel, B

    2001-08-01

    This work presents data on the structure and corrosion resistance of titanium after calcium-ion implantation with a dose of 10(17) Ca+/cm2. The ion energy was 25 keV. Transmission electron microscopy was used to investigate the microstructure of the implanted layer. The chemical composition of the surface layer was examined by XPS and SIMS. The corrosion resistance was examined by electrochemical methods in a simulated body fluid (SBF) at a temperature of 37 degrees C. Biocompatibility tests in vitro were performed in a culture of human derived bone cells (HDBC) in direct contact with the materials tested. Both, the viability of the cells determined by an XTT assay and activity of the cells evaluated by alkaline phosphatase activity measurements in contact with implanted and non-implanted titanium samples were detected. The morphology of the cells spread on the surface of the materials examined was also observed. The results confirmed the biocompatibility of both calcium-ion-implanted and non-implanted titanium under the conditions of the experiment. As shown by TEM results, the surface layer formed during calcium-ion implantation was amorphous. The results of electrochemical examinations indicate that calcium-ion implantation increases the corrosion resistance, but only under stationary conditions; during anodic polarization the calcium-ion-implanted samples undergo pitting corrosion. The breakdown potential is high (2.7-3 V).

  8. Microstructure and Corrosion Resistance of Electrodeposited Ni-Cu-Mo Alloy Coatings

    NASA Astrophysics Data System (ADS)

    Meng, Xinjing; Shi, Xi; Zhong, Qingdong; Shu, Mingyong; Xu, Guanquan

    2016-11-01

    This paper deals with the electrodeposition of Ni-Cu-Mo ternary alloy coatings on low-carbon steel substrate from an aqueous citrate sulfate bath. The structures and microstructure of coatings were characterized by scanning electron microscopy and x-ray diffractometry. The corrosion resistance of coatings was investigated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy techniques. The results show that the Ni-Cu-Mo coatings are mainly composed of fcc-Ni phase and a small amount of NiCu phase. Ni-Cu-Mo coatings exhibit a nodular surface morphology, and the roughness of electroplated coating increases with the increasing of Na2MoO4·2H2O in the bath. The corrosion performance of the coatings is significantly affected by the Mo content of the alloy coating and their surface morphology. The coating prepared in bath containing 40 g/L Na2MoO4·2H2O has the highest corrosion resistance in 3.5 wt.% NaCl solution, while that prepared in bath containing 60 g/L (or more) Na2MoO4·2H2O shows a lower corrosion resistance due to the presence of microcracks on the coating surface.

  9. Alloy 31, a new 6 moly stainless steel with improved corrosion resistance in seawater

    SciTech Connect

    Jasner, M.; Heubner, U.

    1995-10-01

    Alloy 31--UNS N08031--31Ni-27Cr-6.5Mo-1.2Cu-0.2N-balance iron--is an advanced 6 Mo stainless steel with increased chromium and nickel, contents for seawater service. In hot seawater the pitting potential of alloy 31 remains high up to 90 C (194 F). Investigations of resistance to crevice corrosion in real piping systems in natural seawater, both North Sea and Baltic Sea, show that the threshold conditions for alloy 31 in chlorinated seawater (North Sea) are at 40 C and 1 ppm chlorine well superior to the 6 Mo stainless grades being currently in use. In addition, alloy 31 shows an excellent resistance to corrosion versus both hot reducing media (e.g. H{sub 2}SO{sub 4}) and hot oxidizing media (e.g. HNO{sub 3}). The combination of high resistance to localized corrosion vs. hot chloride-bearing cooling waters including seawater and aggressive oxidizing and reducing hot corrosive media is a unique feature of alloy 31. Alloy 31 is recommended for the construction of heat exchangers, process coolers and piping systems. The material is supplied in a number of semifinished products such as seamless and welded pipes, fittings, flanges, forged bars, plate, sheet, strip, wire and prefabricated piping systems.

  10. Effect of alloying elements Al and Ca on corrosion resistance of plasma anodized Mg alloys

    NASA Astrophysics Data System (ADS)

    Anawati, Asoh, Hidetaka; Ono, Sachiko

    2016-04-01

    Plasma anodizing is a surface treatment used to form a ceramic-type oxide film on Mg alloys by the application of a high anodic voltage to create intense plasma near the metal surface. With proper selection of the process parameters, the technique can produce high quality oxide with superior adhesion, corrosion resistance, micro-hardness, wear resistance and strength. The effect of alloying element Al on plasma anodizing process of Mg alloys was studied by comparing the anodizing curves of pure Mg, AZ31, and AZ61 alloys while the effect of Ca were studied on AZ61 alloys containing 0, 1, and 2 wt% Ca. Anodizing was performed in 0.5 M Na3PO4 solution at a constant current density of 200 Am-2 at 25°C. Anodic oxide films with lava-like structure having mix composition of amorphous and crystal were formed on all of the alloys. The main crystal form of the oxide was Mg3(PO4)2 as analyzed by XRD. Alloying elements Al and Ca played role in modifying the plasma lifetime during anodization. Al tended to extend the strong plasma lifetime and therefore accelerated the film thickening. The effect of Ca on anodizing process was still unclear. The anodic film thickness and chemical composition were altered by the presence of Ca in the alloys. Electrochemical corrosion test in 0.9% NaCl solution showed that the corrosion behavior of the anodized specimens depend on the behavior of the substrate. Increasing Al and Ca content in the alloys tended to increase the corrosion resistance of the specimens. The corrosion resistance of the anodized specimens improved significantly about two orders of magnitude relative to the bare substrate.

  11. Prediction of Corrosion Resistance of Some Dental Metallic Materials with an Adaptive Regression Model

    NASA Astrophysics Data System (ADS)

    Chelariu, Romeu; Suditu, Gabriel Dan; Mareci, Daniel; Bolat, Georgiana; Cimpoesu, Nicanor; Leon, Florin; Curteanu, Silvia

    2015-04-01

    The aim of this study is to investigate the electrochemical behavior of some dental metallic materials in artificial saliva for different pH (5.6 and 3.4), NaF content (500 ppm, 1000 ppm, and 2000 ppm), and with albumin protein addition (0.6 wt.%) for pH 3.4. The corrosion resistance of the alloys was quantitatively evaluated by polarization resistance, estimated by electrochemical impedance spectroscopy method. An adaptive k-nearest-neighbor regression method was applied for evaluating the corrosion resistance of the alloys by simulation, depending on the operation conditions. The predictions provided by the model are useful for experimental practice, as they can replace or, at least, help to plan the experiments. The accurate results obtained prove that the developed model is reliable and efficient.

  12. Mechanical properties and oxidation and corrosion resistance of reduced-chromium 304 stainless steel alloys

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Barrett, C. A.; Gyorgak, C. A.

    1979-01-01

    An experimental program was undertaken to identify effective substitutes for part of the Cr in 304 stainless steel as a method of conserving the strategic element Cr. Although special emphasis was placed on tensile properties, oxidation and corrosion resistance were also examined. Results indicate that over the temperature range of -196 C to 540 C the yield stress of experimental austenitic alloys with only 12 percent Cr compare favorably with the 18 percent Cr in 304 stainless steel. Oxidation resistance and in most cases corrosion resistance for the experimental alloys were comparable to the commercial alloy. Effective substitutes for Cr included Al, Mo, Si, Ti, and V, while Ni and Mn contents were increased to maintain an austenitic structure.

  13. Towards a Better Corrosion Resistance and Biocompatibility Improvement of Nitinol Medical Devices

    NASA Astrophysics Data System (ADS)

    Rokicki, Ryszard; Hryniewicz, Tadeusz; Pulletikurthi, Chandan; Rokosz, Krzysztof; Munroe, Norman

    2015-04-01

    Haemocompatibility of Nitinol implantable devices and their corrosion resistance as well as resistance to fracture are very important features of advanced medical implants. The authors of the paper present some novel methods capable to improve Nitinol implantable devices to some marked degree beyond currently used electropolishing (EP) processes. Instead, a magnetoelectropolishing process should be advised. The polarization study shows that magnetoelectropolished Nitinol surface is more corrosion resistant than that obtained after a standard EP and has a unique ability to repassivate the surface. Currently used sterilization processes of Nitinol implantable devices can dramatically change physicochemical properties of medical device and by this influence its biocompatibility. The Authors' experimental results clearly show the way to improve biocompatibility of NiTi alloy surface. The final sodium hypochlorite treatment should replace currently used Nitinol implantable devices sterilization methods which rationale was also given in our previous study.

  14. Studies of Corrosion Resistant Materials Being Considered for High-Level Nuclear Waste Containment in Yucca Mountain Relevant Environments

    SciTech Connect

    McCright, R.D.; Ilevbare, G.; Estill, J.; Rebak, R.

    2001-12-09

    Containment of spent nuclear fuel and vitrified forms of high level nuclear waste require use of materials that are highly corrosion resistant to all of the anticipated environmental scenarios that can occur in a geological repository. Ni-Cr-Mo Alloy 22 (UNS N60622) is proposed for the corrosion resistant outer barrier of a two-layer waste package container at the potential repository site at Yucca Mountain. A range of water compositions that may contact the outer barrier is under consideration, and a testing program is underway to characterize the forms of corrosion and to quantify the corrosion rates. Results from the testing support models for long term prediction of the performance of the container. Results obtained to date indicate a very low general corrosion rate for Alloy 22 and very high resistance to all forms of localized and environmentally assisted cracking in environments tested to date.

  15. Corrosion resistance of the soldering joint of post-soldering of palladium-based metal-ceramic alloys.

    PubMed

    Kawada, E; Sakurai, Y; Oda, Y

    1997-05-01

    To evaluate the corrosion resistance of post soldering of metal-ceramic alloys, four commercially available palladium-system metal-ceramic alloys (Pd-Cu, Pd-Ni, Pd-Ag, and Pd-Sb systems) and two types of solder (12 k gold solder and 16 k gold solder) with different compositions and melting points were used. The corrosion resistance of the soldered joint was evaluated by anodic polarization. The electrochemical characteristics of soldered surface were measured using electrochemical equipment. Declines in corrosion resistance were not detectable with Pd-Cu, Pd-Ag and Pd-Sb types, but break down at low potential occurred with Pd-Ni type.

  16. Improved corrosion resistance of 316L stainless steel by nanocrystalline and electrochemical nitridation in artificial saliva solution

    NASA Astrophysics Data System (ADS)

    Lv, Jinlong; Liang, Tongxiang

    2015-12-01

    The fluoride ion in artificial saliva significantly changed semiconductor characteristic of the passive film formed on the surface of 316L stainless steels. The electrochemical results showed that nanocrystalline α‧-martensite improved corrosion resistance of the stainless steel in a typical artificial saliva compared with coarse grained stainless steel. Moreover, comparing with nitrided coarse grained stainless steel, corrosion resistance of the nitrided nanocrystalline stainless steel was also improved significantly, even in artificial saliva solution containing fluoride ion. The present study showed that the cryogenic cold rolling and electrochemical nitridation improved corrosion resistance of 316L stainless steel for the dental application.

  17. Capabilities to improve corrosion resistance of fuel claddings by using powerful laser and plasma sources

    NASA Astrophysics Data System (ADS)

    Borisov, V. M.; Trofimov, V. N.; Sapozhkov, A. Yu.; Kuzmenko, V. A.; Mikhaylov, V. B.; Cherkovets, V. Ye.; Yakushkin, A. A.; Yakushin, V. L.; Dzhumayev, P. S.

    2016-12-01

    The treatment conditions of fuel claddings of the E110 alloy by using powerful UV or IR laser radiation, which lead to the increase in the corrosion resistance at the high-temperature ( T = 1100°C) oxidation simulating a loss-of-coolant accident, are determined. The possibility of the complete suppression of corrosion under these conditions by using pulsed laser deposition of a Cr layer is demonstrated. The behavior of protective coatings of Al, Al2O3, and Cr planted on steel EP823 by pulsed laser deposition, which is planned to be used in the BREST-OD-300, is studied. The methods of the almost complete suppression of corrosion in liquid lead to the temperature of 720°C are shown.

  18. Polyoxometalate ionic liquids as self-repairing acid-resistant corrosion protection.

    PubMed

    Herrmann, Sven; Kostrzewa, Monika; Wierschem, Andreas; Streb, Carsten

    2014-12-01

    Corrosion is a global problem for any metallic structure or material. Herein we show how metals can easily be protected against acid corrosion using hydrophobic polyoxometalate-based ionic liquids (POM-ILs). Copper metal disks were coated with room-temperature POM-ILs composed of transition-metal functionalized Keggin anions [SiW11 O39 TM(H2 O)](n-) (TM=Cu(II) , Fe(III) ) and quaternary alkylammonium cations (Cn H2 n+1 )4 N(+) (n=7-8). The corrosion resistance against acetic acid vapors and simulated "acid rain" was significantly improved compared with commercial ionic liquids or solid polyoxometalate coatings. Mechanical damage to the POM-IL coating is self-repaired in less than one minute with full retention of the acid protection properties. The coating can easily be removed and recovered by rinsing with organic solvents.

  19. Plasma Electrolytic Oxidation (PEO) Coatings on an A356 Alloy for Improved Corrosion and Wear Resistance

    NASA Astrophysics Data System (ADS)

    Peng, Zhijing

    Plasma electrolytic oxidizing (PEO) is an advanced technique that has been used to deposit thick and hard ceramic coatings on aluminium (Al) alloys. This work was however to use the PEO process to produce thin ceramic oxide coatings on an A356 Al alloy for improving corrosion and wear resistance of the alloy. Effects of current density and treatment time on surface morphologies and thickness of the PEO coatings were investigated. The improvement of galvanic corrosion properties of the coated A356 alloy vs. steel and carbon fibre were evaluated in E85 fuel or NaCl environments. Tribological properties of the coatings were studied with comparison to the uncoated A356 substrate and other commercially-used engine bore materials. The research results indicated that the PEO coatings could have excellent tribological and corrosion properties for aluminium engine applications.

  20. Corrosion resistance, mechanical properties, corrosion fatigue strength and cytocompatibility of new Ti alloys without Al and V.

    PubMed

    Okazaki, Y; Rao, S; Ito, Y; Tateishi, T

    1998-07-01

    The effects of various metallic ions using various metallic powders on the relative growth ratio of fibroblasts L929 and osteoblasts MC3T3-E1 cells were carried out. Ti, Zr, Sn, Nb and Ta had evidently no effect on the relative growth ratios of cells. Otherwise, Al and V ions exhibit cytotoxicity from a concentration of > or = 0.2 ppm. This Al effect on cells tend to be stronger in medium containing small quantity of V ions (< or = 0.03 ppm). The new Ti-15%Zr-4%Nb-4%Ta-0.2%Pd alloy exhibited a higher corrosion resistance in physiological saline solution. The addition of 0.02%O and 0.05%N to Ti-Zr alloy improved the mechanical properties at room temperature and corrosion fatigue strength. The relative growth ratios for the new Ti alloy plate and the alloy block extraction were unity. Further, the relative growth ratios were almost unity for the new Ti alloy against apatite ceramic pins up to 10(5) wear cycles in Eagle's MEM solution. However, there was a sharp decrease for Ti-6%Al-4%V ELI alloy from 3 x 10(4) wear cycles as V ion was released during wear into the wear test solution since the pH of the Eagle's MEM increases with increasing wear cycles.

  1. Mechanically reliable surface oxides for high-temperature corrosion resistance

    SciTech Connect

    Natesan, K.; Veal, B.W.; Grimsditch, M.; Renusch, D.; Paulikas, A.P.

    1995-05-01

    Corrosion is widely recognized as being important, but an understanding of the underlying phenomena involves factors such as the chemistry and physics of early stages of oxidation, chemistry and bonding at the substrate/oxide interface, role of segregants on the strength of that bond, transport processes through scale, mechanisms of residual stress generation and relief, and fracture behavior at the oxide/substrate interface. Because of this complexity a multilaboratory program has been initiated under the auspices of the DOE Center of Excellence for the Synthesis and Processing of Advanced Materials, with strong interactions and cross-leveraging with DOE Fossil Energy and US industry. Objective is to systematically generate the knowledge required to establish a scientific basis for designing and synthesizing improved protective oxide scales/coatings (slow-growing, adherent, sound) on high-temperature materials without compromising the requisite properties of the bulk materials. The objectives of program work at Argonne are to (1) correlate actual corrosion performance with stresses, voids, segregants, interface roughness, initial stages of oxidation, and microstructures; (2) study such behavior in growing or as-grown films; and (3) define prescriptive design and synthesis routes to mechanically reliable surface oxides. Several techniques, such as Auger electron spectroscopy, X-ray diffraction, X-ray grazing incidence reflectance, grazing-angle X-ray fluorescence, optical fluorescence, and Raman spectroscopy, are used in the studies. Tne project has selected Fe-25 wt.% Cr-20 wt.% Ni and Fe-Cr-Al alloys, which are chromia- and alumina-formers respectively, for the studies. This paper presents some of the results on early stages of oxidation and on surface segregation of elements.

  2. The effect of fatigue on the corrosion resistance of common medical alloys.

    PubMed

    Di Prima, Matthew; Gutierrez, Erick; Weaver, Jason D

    2016-07-04

    The effect of mechanical fatigue on the corrosion resistance of medical devices has been a concern for devices that experience significant fatigue during their lifespan and devices made from metallic alloys. The Food and Drug Administration had recommended in some instances for corrosion testing to be performed on post-fatigued devices [Non-clinical tests and recommended labeling for intravascular stents and associated delivery systems: guidance for industry and FDA staff. 2005: Food and Drug Administration, Center for Devices and Radiological Health], although the need for this has been debated [Nagaraja S, et al., J Biomed Mater Res Part B: Appl Biomater 2016, 8.] This study seeks to evaluate the effect of fatigue on the corrosion resistance of 5 different materials commonly used in medical devices: 316 LVM stainless steel, MP35N cobalt chromium, electropolished nitinol, mechanically polished nitinol, and black oxide nitinol. Prior to corrosion testing per ASTM F2129, wires of each alloy were split into subgroups and subjected to either nothing (that is, as received); high strain fatigue for less than 8 min; short-term phosphate buffered saline (PBS) soak for less than 8 min; low strain fatigue for 8 days; or long-term PBS soak for 8 days. Results from corrosion testing showed that the rest potential trended to an equilibrium potential with increasing time in PBS and that there was no statistical (p > 0.05) difference in breakdown potential between the fatigued and matching PBS soak groups for 9 out of 10 test conditions. Our results suggest that under these nonfretting conditions, corrosion susceptibility as measured by breakdown potential per ASTM F2129 was unaffected by the fatigue condition. 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  3. Effect of wire fretting on the corrosion resistance of common medical alloys.

    PubMed

    Siddiqui, Danyal A; Sivan, Shiril; Weaver, Jason D; Di Prima, Matthew

    2016-09-23

    Metallic medical devices such as intravascular stents can undergo fretting damage in vivo that might increase their susceptibility to pitting corrosion. As a result, the US Food and Drug Administration has recommended that such devices be evaluated for corrosion resistance after the devices have been fatigue tested in situations where significant micromotion can lead to fretting damage. Three common alloys that cardiovascular implants are made from [MP35N cobalt chromium (MP35N), electropolished nitinol (EP NiTi), and 316LVM stainless steel (316LVM)] were selected for this study. In order to evaluate the effect of wire fretting on the pitting corrosion susceptibility of these medical alloys, small and large fretting scar conditions of each alloy fretting against itself, and the other alloys in phosphate buffered saline (PBS) at 37°C were tested per ASTM F2129 and compared against as received or PBS immersed control specimens. Although the general trend observed was that fretting damage significantly lowered the rest potential (Er ) of these specimens (p < 0.01), fretting damage had no significant effect on the breakdown potential (Eb , p > 0.05) and hence did not affect the susceptibility to pitting corrosion. In summary, our results demonstrate that fretting damage in PBS alone is not sufficient to cause increased susceptibility to pitting corrosion in the three common alloys investigated. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  4. Corrosion resistance of stressed NiTi and stainless steel orthodontic wires in acid artificial saliva.

    PubMed

    Huang, Her-Hsiung

    2003-09-15

    The purpose of this study was to investigate the corrosion resistance of stressed NiTi and stainless steel orthodontic wires using cyclic potentiodynamic and potentiostatic tests in acid artificial saliva at 37 degrees C. An atomic force microscope was used to measure the 3-D surface topography of as-received wires. Scanning electron microscope observations were carried out before and after the cyclic potentiodynamic tests. The surface chemical analysis was characterized using X-ray photoelectron spectroscopy and Auger electron spectroscopy after the potentiostatic tests. The cyclic potentiodynamic test results showed that the pH had a significant influence on the corrosion parameters of the stressed NiTi and stainless steel wires (p < 0.05). The pitting potential, protection potential, and passive range of stressed NiTi and stainless steel wires decreased on decreasing pH, whereas the passive current density increased on decreasing pH. The load had no significant influence on the above corrosion parameters (p > 0.05). For all pH and load conditions, stainless steel wire showed higher pitting potential and wider passive range than NiTi wire (p < 0.001), whereas NiTi wire had lower passive current density than stainless steel wire (p < 0.001). The corrosion resistance of the stressed NiTi and stainless steel wires was related to the surface characterizations, including surface defect and passive film.

  5. Enhanced Corrosion Resistance of PVD-CrN Coatings by ALD Sealing Layers.

    PubMed

    Wan; Zhang, Teng Fei; Ding, Ji Cheng; Kim, Chang-Min; Park, So-Won; Yang, Yang; Kim, Kwang-Ho; Kwon, Se-Hun

    2017-12-01

    Multilayered hard coatings with a CrN matrix and an Al2O3, TiO2, or nanolaminate-Al2O3/TiO2 sealing layer were designed by a hybrid deposition process combined with physical vapor deposition (PVD) and atomic layer deposition (ALD). The strategy was to utilize ALD thin films as pinhole-free barriers to seal the intrinsic defects to protect the CrN matrix. The influences of the different sealing layers added in the coatings on the microstructure, surface roughness, and corrosion behaviors were investigated. The results indicated that the sealing layer added by ALD significantly decreased the average grain size and improved the corrosion resistance of the CrN coatings. The insertion of the nanolaminate-Al2O3/TiO2 sealing layers resulted in a further increase in corrosion resistance, which was attributed to the synergistic effect of Al2O3 and TiO2, both acting as excellent passivation barriers to the diffusion of corrosive substances.

  6. Evaluation of cytotoxicity and corrosion resistance of orthodontic mini-implants

    PubMed Central

    Alves, Celha Borges Costa; Segurado, Márcio Nunes; Dorta, Miriam Cristina Leandro; Dias, Fátima Ribeiro; Lenza, Maurício Guilherme; Lenza, Marcos Augusto

    2016-01-01

    ABSTRACT Objective: To evaluate and compare in vitro cytotoxicity and corrosion resistance of mini-implants from three different commercial brands used for orthodontic anchorage. Methods: Six mini-implants (Conexão(tm), Neodent(tm) and SIN(tm)) were separately immersed in artificial saliva (pH 6.76) for 30 and 60 days. The cytotoxicity of the corrosion extracts was assessed in L929 cell cultures using the violet crystal and MTT assays, as well as cell morphology under light microscopy. Metal surface characteristics before and after immersion in artificial saliva were assessed by means of scanning electron microscopy (SEM). The samples underwent atomic absorption spectrophotometry to determine the concentrations of aluminum and vanadium ions, constituent elements of the alloy that present potential toxicity. For statistical analysis, one-way ANOVA/Bonferroni tests were used for comparisons among groups with p < 0.05 considered significant. Statistical analysis was carried out with Graph Pad PRISM software Version 4.0. Results: No changes in cell viability or morphology were observed. Mini-implants SEM images revealed smooth surfaces with no obvious traces of corrosion. The extracts assessed by means of atomic absorption spectrophotometry presented concentrations of aluminum and vanadium ions below 1.0 µg/mL and 0.5 µg/mL, respectively. Conclusion: Orthodontic mini-implants manufactured by Conexão(tm), Neodent(tm) and SIN(tm) present high corrosion resistance and are not cytotoxic. PMID:27901227

  7. Improve sensitization and corrosion resistance of an Al-Mg alloy by optimization of grain boundaries

    PubMed Central

    Yan, Jianfeng; Heckman, Nathan M.; Velasco, Leonardo; Hodge, Andrea M.

    2016-01-01

    The sensitization and subsequent intergranular corrosion of Al-5.3 wt.% Mg alloy has been shown to be an important factor in stress corrosion cracking of Al-Mg alloys. Understanding sensitization requires the review of grain boundary character on the precipitation process which can assist in developing and designing alloys with improved corrosion resistance. This study shows that the degree of precipitation in Al-Mg alloy is dependent on grain boundary misorientation angle, adjacent grain boundary planes and grain boundary types. The results show that the misorientation angle is the most important factor influencing precipitation in grain boundaries of the Al-Mg alloy. Low angle grain boundaries (≤15°) have better immunity to precipitation and grain boundary acid attack. High angle grain boundaries (>15°) are vulnerable to grain boundary acid attack. Grain boundaries with adjacent plane orientations near to {100} have potential for immunity to precipitation and grain boundary acid attack. This work shows that low Σ (Σ ≤ 29) coincident site lattice (CSL) grain boundaries have thinner β precipitates. Modified nitric acid mass loss test and polarization test demonstrated that the global corrosion resistance of sputtered Al-Mg alloy is enhanced. This may be attributed to the increased fractions of low Σ (Σ ≤ 29) CSL grain boundaries after sputtering. PMID:27230299

  8. Improve sensitization and corrosion resistance of an Al-Mg alloy by optimization of grain boundaries

    NASA Astrophysics Data System (ADS)

    Yan, Jianfeng; Heckman, Nathan M.; Velasco, Leonardo; Hodge, Andrea M.

    2016-05-01

    The sensitization and subsequent intergranular corrosion of Al-5.3 wt.% Mg alloy has been shown to be an important factor in stress corrosion cracking of Al-Mg alloys. Understanding sensitization requires the review of grain boundary character on the precipitation process which can assist in developing and designing alloys with improved corrosion resistance. This study shows that the degree of precipitation in Al-Mg alloy is dependent on grain boundary misorientation angle, adjacent grain boundary planes and grain boundary types. The results show that the misorientation angle is the most important factor influencing precipitation in grain boundaries of the Al-Mg alloy. Low angle grain boundaries (≤15°) have better immunity to precipitation and grain boundary acid attack. High angle grain boundaries (>15°) are vulnerable to grain boundary acid attack. Grain boundaries with adjacent plane orientations near to {100} have potential for immunity to precipitation and grain boundary acid attack. This work shows that low Σ (Σ ≤ 29) coincident site lattice (CSL) grain boundaries have thinner β precipitates. Modified nitric acid mass loss test and polarization test demonstrated that the global corrosion resistance of sputtered Al-Mg alloy is enhanced. This may be attributed to the increased fractions of low Σ (Σ ≤ 29) CSL grain boundaries after sputtering.

  9. Influence of Processing and Heat Treatment on Corrosion Resistance and Properties of High Alloyed Steel Coatings

    NASA Astrophysics Data System (ADS)

    Hill, Horst; Weber, Sebastian; Raab, Ulrich; Theisen, Werner; Wagner, Lothar

    2012-09-01

    Corrosion and abrasive wear are two important aspects to be considered in numerous engineering applications. Looking at steels, high-chromium high-carbon tool steels are proper and cost-efficient materials. They can either be put into service as bulk materials or used as comparatively thin coatings to protect lower alloyed construction or heat treatable steels from wear and corrosion. In this study, two different corrosion resistant tool steels were used for the production of coatings and bulk material. They were processed by thermal spraying and super solidus liquid phase sintering as both processes can generally be applied to produce coatings on low alloyed substrates. Thermally sprayed (high velocity oxygen fuel) coatings were investigated in the as-processed state, which is the most commonly used condition for technical applications, and after a quenching and tempering treatment. In comparison, sintered steels were analyzed in the quenched and tempered condition only. Significant influence of alloy chemistry, processing route, and heat treatment on tribological properties was found. Experimental investigations were supported by computational thermodynamics aiming at an improvement of tribological and corrosive resistance.

  10. Development of Custom 465® Corrosion-Resisting Steel for Landing Gear Applications

    NASA Astrophysics Data System (ADS)

    Daymond, Benjamin T.; Binot, Nicolas; Schmidt, Michael L.; Preston, Steve; Collins, Richard; Shepherd, Alan

    2016-04-01

    Existing high-strength low-alloy steels have been in place on landing gear for many years owing to their superior strength and cost performance. However, there have been major advances in improving the strength of high-performance corrosion-resisting steels. These materials have superior environmental robustness and remove the need for harmful protective coatings such as chromates and cadmium now on the list for removal under REACH legislation. A UK government-funded collaborative project is underway targeting a refined specification Custom 465® precipitation hardened stainless steel to replace the current material on Airbus A320 family aircraft main landing gear, a main fitting component developed by Messier-Bugatti-Dowty. This is a collaborative project between Airbus, Messier-Bugatti-Dowty, and Carpenter Technology Corporation. An extensive series of coupon tests on four production Heats of the material have been conducted, to obtain a full range of mechanical, fatigue, and corrosion properties. Custom 465® is an excellent replacement to the current material, with comparable tensile strength and fracture toughness, better ductility, and very good general corrosion and stress corrosion cracking resistance. Fatigue performance is the only significant area of deficit with respect to incumbent materials, fatigue initiation being often related to carbo-titanium-nitride particles and cleavage zones.

  11. Effect of Thermal Oxidation on Corrosion Resistance of Commercially Pure Titanium in Acid Medium

    NASA Astrophysics Data System (ADS)

    Jamesh, M.; Kumar, Satendra; Sankara Narayanan, T. S. N.

    2012-06-01

    This article addresses the characteristics of commercially pure titanium (CP-Ti) subjected to thermal oxidation in air at 650 °C for 48 h and its corrosion behavior in 0.1 and 4 M HCl and HNO3 mediums. Thermal oxidation of CP-Ti leads to the formation of thick oxide scales (~20 μm) throughout its surface without any spallation. The oxide layer consists of rutile- and oxygen-diffused titanium as predominant phases with a hardness of 679 ± 43 HV1.96. Electrochemical studies reveal that the thermally oxidized CP-Ti offers a better corrosion resistance than its untreated counterpart in both HCl and HNO3 mediums. The uniform surface coverage and compactness of the oxide layer provide an effective barrier toward corrosion of CP-Ti. The study concludes that thermal oxidation is an effective approach to engineer the surface of CP-Ti so as to increase its corrosion resistance in HCl and HNO3 mediums.

  12. Incorporating Nano-silica as a Binder to Improve Corrosion Resistance of High Alumina Refractory Castables

    NASA Astrophysics Data System (ADS)

    Ramezani, Abbas; Mohebi, Mohammad Masoud; Souri, Alireza

    2013-04-01

    In this study, four types of castables as calcium-aluminate cement (CAC)-bonded and nano-silica (NS)-bonded castables based on tabular-alumina and bauxite aggregates were prepared to investigate the replacement of the calcium-aluminate cement by NS. All samples were allowed to dry at 110 °C then fired at 800 and 1200 °C. Bulk density and apparent porosity of samples were measured. The molten aluminum static corrosion test (cup test) results showed that NS-bonded specimens had higher resistance to corrosion compared to CAC-bonded samples (based on the measured average aluminum penetration depth into the refractory texture). However no penetration was observed in bauxite NS-bonded samples. The results were consistent with dynamic corrosion test in aluminum melt carried out at 800 °C for 100 h. The small pore size in NS-bonded castables was found to be the main cause for high corrosion resistance as micro-pores prevented the melt to penetrate into the refractory.

  13. Enhanced antimicrobial properties, cytocompatibility, and corrosion resistance of plasma-modified biodegradable magnesium alloys.

    PubMed

    Zhao, Ying; Jamesh, Mohammed Ibrahim; Li, Wing Kan; Wu, Guosong; Wang, Chenxi; Zheng, Yufeng; Yeung, Kelvin W K; Chu, Paul K

    2014-01-01

    Magnesium alloys are potential biodegradable materials and have received increasing attention due to their outstanding biological performance and mechanical properties. However, rapid degradation in the physiological environment and potential toxicity limit clinical applications. Recently, special magnesium-calcium (Mg-Ca) and magnesium-strontium (Mg-Sr) alloys with biocompatible chemical compositions have been reported, but the rapid degradation still does not meet clinical requirements. In order to improve the corrosion resistance, a rough, hydrophobic and ZrO(2)-containing surface film is fabricated on Mg-Ca and Mg-Sr alloys by dual zirconium and oxygen ion implantation. Weight loss measurements and electrochemical corrosion tests show that the corrosion rate of the Mg-Ca and Mg-Sr alloys is reduced appreciably after surface treatment. A systematic investigation of the in vitro cellular response and antibacterial capability of the modified binary magnesium alloys is performed. The amounts of adherent bacteria on the Zr-O-implanted and Zr-implanted samples diminish remarkably compared to the unimplanted control. In addition, significantly enhanced cell adhesion and proliferation are observed from the Zr-O-implanted sample. The results suggest that dual zirconium and oxygen ion implantation, which effectively enhances the corrosion resistance, in vitro biocompatibility and antimicrobial properties of Mg-Ca and Mg-Sr alloys, provides a simple and practical means to expedite clinical acceptance of biodegradable magnesium alloys.

  14. Pulse electrodeposited nickel using sulphamate electrolyte for hardness and corrosion resistance

    SciTech Connect

    Sivasakthi, P.; Sekar, R.; Bapu, G.N.K.Ramesh

    2015-10-15

    Highlights: • Nickel deposits from sulphamate solutions using pulse method are prepared. • Effect of duty cycle and frequency are studied. • XRD, SEM and AFM of the nickel deposits are characterized. • Corrosion characteristics of the nickel deposit are reported. - Abstract: Nickel deposits have been obtained on mild steel substrate by pulse current (PC) electrodeposition method using nickel sulphamate electrolyte. Micro hardness values increased with decreasing duty cycle and pulse frequency. X-ray diffraction studies revealed that (2 0 0) plane was predominant and the nickel deposit obtained at low duty cycle and low frequency has the smallest grain size. The surface morphology of the coatings was explored by scanning electron microscopy (SEM) and atomic force microscopy. These studies showed that the microstructure of the nickel coatings changed from pyramidal structure to homogeneous structure with increasing duty cycle and pulse frequencies. The corrosion resistance of coatings was evaluated by potentiodynamic polarization and electrochemical impedance studies in 3.5 wt% sodium chloride (NaCl) solutions. An enhancement of the corrosion resistance, charge-transfer resistance and wear resistance has been obtained at low duty cycle and low frequencies.

  15. Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

    SciTech Connect

    Bhatt, R.B.; Kamat, H.S.; Ghosal, S.K.; De, P.K.

    1999-10-01

    The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance of pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constituent phases, which are responsible for improved resistance to pitting corrosion.

  16. 16 CFR 23.10 - Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Misuse of âcorrosion proof,â ânoncorrosive,â âcorrosion resistant,â ârust proof,â ârust resistant,â etc. 23.10 Section 23.10 Commercial Practices FEDERAL TRADE COMMISSION GUIDES AND TRADE PRACTICE RULES GUIDES FOR THE JEWELRY, PRECIOUS METALS, AND...

  17. 16 CFR 23.10 - Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Misuse of âcorrosion proof,â ânoncorrosive,â âcorrosion resistant,â ârust proof,â ârust resistant,â etc. 23.10 Section 23.10 Commercial Practices FEDERAL TRADE COMMISSION GUIDES AND TRADE PRACTICE RULES GUIDES FOR THE JEWELRY, PRECIOUS METALS, AND...

  18. 16 CFR 23.10 - Misuse of “corrosion proof,” “noncorrosive,” “corrosion resistant,” “rust proof,” “rust resistant...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Misuse of âcorrosion proof,â ânoncorrosive,â âcorrosion resistant,â ârust proof,â ârust resistant,â etc. 23.10 Section 23.10 Commercial Practices FEDERAL TRADE COMMISSION GUIDES AND TRADE PRACTICE RULES GUIDES FOR THE JEWELRY, PRECIOUS METALS, AND...

  19. Corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments

    NASA Astrophysics Data System (ADS)

    Kusada, Kentaro

    The objective of this study is to evaluate corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments. Al5052-H3 and Al6061-T6 were selected as substrates, and HCLCoat11 and HCLCoat13 developed in the Hawaii Corrosion Laboratory were selected for the siloxane ceramic/polymer coatings. The HCLCoat11 is a quasi-ceramic coating that has little to no hydrocarbons in its structure. The HCLCoat13 is formulated to incorporate more hydrocarbons to improve adhesion to substrate surfaces with less active functionalities. In this study, two major corrosion evaluation methods were used, which were the polarization test and the immersion test. The polarization tests provided theoretical corrosion rates (mg/dm 2/day) of bare, HCLCoat11-coated, and HCLCoat13-coated aluminum alloys in aerated 3.15wt% sodium chloride solution. From these results, the HCLCoat13-coated Al5052-H3 was found to have the lowest corrosion rate which was 0.073mdd. The next lowest corrosion rate was 0.166mdd of the HCLCoat11-coated Al5052-H3. Corrosion initiation was found to occur at preexisting breaches (pores) in the films by optical microscopy and SEM analysis. The HCLCoat11 film had many preexisting breaches of 1-2microm in diameter, while the HCLCoat13 film had much fewer preexisting breaches of less than 1microm in diameter. However, the immersion tests showed that the seawater immersion made HCLCoat13 film break away while the HCLCoat11 film did not apparently degrade, indicating that the HCLCoat11 film is more durable against seawater than the HCLCoat13. Raman spectroscopy revealed that there was some degradation of HCLCoat11 and HCLCoat13. For the HCLCoat11 film, the structure relaxation of Si-O-Si linkages was observed. On the other hand, seawater generated C-H-S bonds in the HCLCoat13 film resulting in the degradation of the film. In addition, it was found that the HCLCoat11 coating had anti-fouling properties due to its high water contact

  20. Effects of residual water in the pores of aluminum anodic oxide layers prior to sealing on corrosion resistance

    NASA Astrophysics Data System (ADS)

    Lee, Junghoon; Jung, Uoochang; Kim, Wangryeol; Chung, Wonsub

    2013-10-01

    The effects of residual water in the pores of aluminum anodic oxide layers before the sealing process on corrosion resistance were studied. When residual water was present in pores before cold NiF2 sealing, corrosion resistance was dramatically increased especially in acid chloride electrolyte. It is considered that residual water in pores provides paths that allow sealing media to diffuse through the oxide layer, thereby sealing pores up to inner side of porous layer nearby barrier layer. For hydrothermal sealing, corrosion resistance improvements by residual water were also observed. However, improvements in corrosion resistance by cold NiF2 sealing were greater than those achieved by hydrothermal sealing, due to cracks formation.

  1. 76 FR 20954 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea..., the Department published in the Federal Register the countervailing duty order on...

  2. 75 FR 18153 - Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-09

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Corrosion-Resistant Carbon Steel Flat Products from the Republic of Korea..., the Department published in the Federal Register the countervailing duty order on...

  3. 77 FR 67395 - Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Revised Schedule for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-09

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Revised Schedule for the Subject Reviews AGENCY: United States International Trade Commission. ACTION: Notice. DATES:...

  4. 77 FR 16810 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea..., the Department published in the Federal Register the countervailing duty order on...

  5. Corrosion-resistant front surface aluminum mirror coatings

    NASA Astrophysics Data System (ADS)

    Guenther, Karl H.; Penny, Iain; Willey, Ronald R.

    1993-03-01

    Front surface metal mirrors need protection of the inherently fragile metal film deposited on a glass substrate. Conventional evaporated dielectric thin-film overcoats provide limited protection because of their less than dense packing. These films usually have a columnar structure with voids between the columns. The voids give access to the underlying metal film for humidity and corrosive gases or liquids. Some progress in developing better coatings was made in the early 1980s with ion-assisted deposition. Front surface aluminum mirrors with dielectric thin films deposited by reactive low-voltage ion plating have a still higher survival time, by a factor of up to three under comparable test conditions. The transmission of our best samples increased to only 10 percent when immersed in 0.2 M NaOH for 20 h. By comparison, an unprotected aluminum film dissolves in less than 5 min. Electron beam evaporated dielectric coatings provide protection for about 1.5 to 2 h in the same test solution. The reason for the significant improvement brought about by reactive low-voltage ion plating deposition, and its advantage for large-scale production is discussed.

  6. The biofilm ecology of microbial biofouling, biocide resistance and corrosion

    SciTech Connect

    White, D.C. |; Kirkegaard, R.D.; Palmer, R.J. Jr.; Flemming, C.A.; Chen, G.; Leung, K.T.; Phiefer, C.B.; Arrage, A.A. |

    1997-06-01

    In biotechnological or bioremediation processes it is often the aim to promote biofilm formation, and maintain active, high density biomass. In other situations, biofouling can seriously restrict effective heat transport, membrane processes, and potentate macrofouling with loss of transportation efficiency. In biotechnological or bioremediation processes it is often the aim to promote biofilm formation, and maintain active, high density biomass. In other situations, biofouling can seriously restrict effective heat transport, membrane processes, and potentate macrofouling with loss of transportation efficiency. Heterogeneous distribution of microbes and/or their metabolic activity can promote microbially influenced corrosion (MIC) which is a multibillion dollar problem. Consequently, it is important that biofilm microbial ecology be understood so it can be manipulated rationally. It is usually simple to select organisms that form biofilms by flowing a considerably dilute media over a substratum, and propagating the organisms that attach. To examine the biofilm most expeditiously, the biomass accumulation, desquamation, and metabolic activities need to be monitored on-line and non-destructively. This on-line monitoring becomes even more valuable if the activities can be locally mapped in time and space within the biofilm. Herein the authors describe quantitative measures of microbial biofouling, the ecology of pathogens in drinking water distributions systems, and localization of microbial biofilms and activities with localized MIC.

  7. Ion implantation of surgical Ti-6Al-4V for improved resistance to wear-accelerated corrosion.

    PubMed

    Buchanan, R A; Rigney, E D; Williams, J M

    1987-03-01

    The influence of nitrogen-ion implantation on the wear-accelerated corrosion behavior of surgical Ti-6Al-4V was studied. Nonpassivated and prepassivated unimplanted Ti-6Al-4V specimens were employed as controls for comparison. Corrosion rates as a function of time at open-circuit corrosion potentials were electrochemically measured in saline and serum solutions under both static and wear conditions. The wear parameters simulated those of a total artificial hip under average walking conditions. The results indicated that prepassivation of the control material was beneficial under static-corrosion conditions, but not under wear-corrosion conditions. The nitrogen-ion implantation process was found to significantly improve the material's resistance to wear-accelerated corrosion in both saline and serum solutions.

  8. Nanotextured stainless steel for improved corrosion resistance and biological response in coronary stenting

    NASA Astrophysics Data System (ADS)

    Mohan, Chandini C.; Prabhath, Anupama; Cherian, Aleena Mary; Vadukumpully, Sajini; Nair, Shantikumar V.; Chennazhi, Krishnaprasad; Menon, Deepthy

    2014-12-01

    Nanosurface engineering of metallic substrates for improved cellular response is a persistent theme in biomaterials research. The need to improve the long term prognosis of commercially available stents has led us to adopt a `polymer-free' approach which is cost effective and industrially scalable. In this study, 316L stainless steel substrates were surface modified by hydrothermal treatment in alkaline pH, with and without the addition of a chromium precursor, to generate a well adherent uniform nanotopography. The modified surfaces showed improved hemocompatibility and augmented endothelialization, while hindering the proliferation of smooth muscle cells. Moreover, they also exhibited superior material properties like corrosion resistance, surface integrity and reduced metal ion leaching. The combination of improved corrosion resistance and selective vascular cell viability provided by nanomodification can be successfully utilized to offer a cell-friendly solution to the inherent limitations pertinent to bare metallic stents.

  9. The Corrosion Resistance and Paint Adhesion Properties of Chromate Conversion Coatings on Aluminium and Its Alloys

    DTIC Science & Technology

    1976-05-01

    aluminium and its alloys has been evaluated with respect to both corrosion resistance of, and paint adhesion to, the chromate films. The process involves...The findings in this Report will be used as the basis for a Defence Standard for chromate conversion coatings for aluminium and aluminium alloys...3 PROPRIETARY CHROMATE CONVERSION COATINGS FOR ALUMINIUM 17 4 PAINT ADHESION 19 5 DISCUSSION 21 6 CONCLUSIONS 24 Acknowledgments 25 Appendix A

  10. Silicon nitride: A ceramic material with outstanding resistance to thermal shock and corrosion

    NASA Technical Reports Server (NTRS)

    Huebner, K. H.; Saure, F.

    1983-01-01

    The known physical, mechanical and chemical properties of reaction-sintered silicon nitride are summarized. This material deserves interest especially because of its unusually good resistance to thermal shock and corrosion at high temperatures. Two types are distinguished: reaction-sintered (porous) and hot-pressed (dense) Si3N4. Only the reaction-sintered material which is being produced today in large scale as crucibles, pipes, nozzles and tiles is considered.

  11. Heat treatment of NiCrFe alloy to optimize resistance to intergrannular stress corrosion

    DOEpatents

    Steeves, Arthur F.; Bibb, Albert E.

    1984-01-01

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprising heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cool the alloy body, and heat the cooled body to a temperature between 1100.degree. to 1500.degree. F. for about 1 to 30 hours.

  12. Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

    DOEpatents

    Steeves, A.F.; Bibb, A.E.

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

  13. Corrosion resistant three-dimensional nanotextured silicon for water photo-oxidation

    NASA Astrophysics Data System (ADS)

    Carter, Rachel; Chatterjee, Shahana; Gordon, Evan; Share, Keith; Erwin, William R.; Cohn, Adam P.; Bardhan, Rizia; Pint, Cary L.

    2015-10-01

    We demonstrate the ability to chemically transform bulk silicon into a nanotextured surface that exhibits excellent electrochemical stability in aqueous conditions for water photo-oxidation. Conformal defective graphene coatings on nanotextured silicon formed by thermal treatment enable over 50× corrosion resistance in aqueous electrolytes based upon Tafel analysis and impedance spectroscopy. This enables nanotextured silicon as an effective oxygen-evolution photoanode for water splitting with saturation current density measured near 35 mA cm-2 under 100 mW cm-2 (1 sun) illumination. Our approach builds upon simple and scalable processing techniques with silicon to develop corrosion resistant electrodes that can benefit a broad range of catalytic and photocatalytic applications.We demonstrate the ability to chemically transform bulk silicon into a nanotextured surface that exhibits excellent electrochemical stability in aqueous conditions for water photo-oxidation. Conformal defective graphene coatings on nanotextured silicon formed by thermal treatment enable over 50× corrosion resistance in aqueous electrolytes based upon Tafel analysis and impedance spectroscopy. This enables nanotextured silicon as an effective oxygen-evolution photoanode for water splitting with saturation current density measured near 35 mA cm-2 under 100 mW cm-2 (1 sun) illumination. Our approach builds upon simple and scalable processing techniques with silicon to develop corrosion resistant electrodes that can benefit a broad range of catalytic and photocatalytic applications. Electronic supplementary information (ESI) available: (i) Experimental details, (ii) Nyquist plot from EIS data, (iii) FTIR of H-terminated silicon, (iv) reflectance measurements to quantify light trapping in nanotextured silicon, (v) LSV from Tafel analysis, and (vi) J-V curves for H-terminated flat samples, (vii) stability test of photoanode, and (viii) forward and reverse scans for each sample type. See DOI: 10

  14. Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen

    NASA Astrophysics Data System (ADS)

    Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham; Sarri, Gianluca; Ng, Chi-Ho; Sharba, Ahmed; Man, Hau-Chung

    2016-03-01

    The relatively high elastic modulus coupled with the presence of toxic vanadium (V) in Ti6Al4V alloy has long been a concern in orthopaedic applications. To solve the problem, a variety of non-toxic and low modulus beta-titanium (beta-Ti) alloys have been developed. Among the beta-Ti alloy family, the quaternary Ti-Nb-Zr-Ta (TNZT) alloys have received the highest attention as a promising replacement for Ti6Al4V due to their lower elastic modulus and outstanding long term stability against corrosion in biological environments. However, the inferior wear resistance of TNZT is still a problem that must be resolved before commercialising in the orthopaedic market. In this work, a newly developed laser surface treatment technique was employed to improve the surface properties of Ti-35.3Nb-7.3Zr-5.7Ta alloy. The surface structure and composition of the laser-treated TNZT surface were examined by grazing incidence X-ray diffraction (GI-XRD) and X-ray photoelectron spectroscopy (XPS). The wear and corrosion resistance were evaluated by pin-on-plate sliding test and anodic polarisation test in Hanks' solution. The experimental results were compared with the untreated (or base) TNZT material. The research findings showed that the laser surface treatment technique reported in this work can effectively improve the wear and corrosion resistance of TNZT.

  15. Albumin coatings by alternating current electrophoretic deposition for improving corrosion resistance and bioactivity of titanium implants.

    PubMed

    Höhn, Sarah; Braem, Annabel; Neirinck, Bram; Virtanen, Sannakaisa

    2017-04-01

    Although Ti alloys are generally regarded to be highly corrosion resistant, inflammatory conditions following surgery can instigate breakdown of the TiO2 passivation layer leading to an increased metal ion release. Furthermore proteins present in the surrounding tissue will readily adsorb on a titanium surface after implantation. In this paper alternating current electrophoretic deposition (AC-EPD) of bovine serum albumin (BSA) on Ti6Al4V was investigated in order to increase the corrosion resistance and control the protein adsorption capability of the implant surface. The Ti6Al4V surface was characterized with SEM, XPS and ToF-SIMS after long-term immersion tests under physiological conditions and simulated inflammatory conditions either in Dulbecco's Modified Eagle Medium (DMEM) or DMEM supplemented with fetal calf serum (FCS). The analysis showed an increased adsorption of amino acids and proteins from the different immersion solutions. The BSA coating was shown to prevent selective dissolution of the vanadium (V) rich β-phase, thus effectively limiting metal ion release to the environment. Electrochemical impedance spectroscopy measurements confirmed an increase of the corrosion resistance for BSA coated surfaces as a function of immersion time due to the time-dependent adsorption of the different amino acids (from DMEM) and proteins (from FCS) as observed by ToF-SIMS analysis.

  16. Vacuum ultraviolet fluorine laser formation of corrosion-resistant iron thin films

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Awaihara, Yuta; Yamashita, Tsugito; Inoue, Narumi

    2015-06-01

    Corrosion-, chemical-resistant pure iron thin films were formed by the vacuum ultraviolet fluorine laser of 157 nm wavelength induced surface modification of 30- to 50-nm-thick iron thin films. Transmission electron microscope and electron energy-loss spectroscopy were conducted to analyze structure and oxidation state of the thin modified layer of iron thin films. No rust was observed on the surface of the fluorine laser-irradiated iron thin films in air for 2 years. The samples also showed high chemical resistance to a HNO3 aqueous solution to fabricate a micropattern of pure iron thin films.

  17. Corrosion resistant surface for vanadium nitride and hafnium nitride layers as function of grain size

    NASA Astrophysics Data System (ADS)

    Escobar, C. A.; Caicedo, J. C.; Aperador, W.

    2014-01-01

    In this research it was studied vanadium nitride (VN) and hafnium nitride (HfN) film, which were deposited onto silicon (Si (100)) and AISI 4140 steel substrates via r.f. magnetron sputtering technique in Ar/N2 atmosphere with purity at 99.99% for both V and Hf metallic targets. Both films were approximately 1.2±0.1 μm thick. The crystallography structures that were evaluated via X-ray diffraction analysis (XRD) showed preferential orientations in the Bragg planes VN (200) and HfN (111). The chemical compositions for both films were characterized by EDX. Atomic Force Microscopy (AFM) was used to study the morphology; the results reveal grain sizes of 78±2 nm for VN and 58±2 nm for HfN and roughness values of 4.2±0.1 nm for VN and 1.5±0.1 nm for HfN films. The electrochemical performance in VN and HfN films deposited onto steel 4140 were studied by Tafel polarization curves and impedance spectroscopy methods (EIS) under contact with sodium chloride at 3.5 wt% solution, therefore, it was found that the corrosion rate decreased about 95% in VN and 99% for HfN films in relation to uncoated 4140 steel, thus demonstrating, the protecting effect of VN and HfN films under a corrosive environment as function of morphological characteristics (grain size). VN(grain size)=78±2.0 nm, VN(roughness)=4.2±0.1 nm, VN(corrosion rate)=40.87 μmy. HfN(grain size)=58±2.0 nm, HfN(roughness)=1.5±0.1 nm, HfN(corrosion rate)=0.205 μmy. It was possible to analyze that films with larger grain size, can be observed smaller grain boundary thus generating a higher corrosion rate, therefore, in this work it was found that the HfN layer has better corrosion resistance (low corrosion rate) in relation to VN film which presents a larger grain size, indicating that the low grain boundary in (VN films) does not restrict movement of the Cl- ion and in this way the corrosion rate increases dramatically.

  18. Corrosion-resistant amorphous metallic coatings: Engineering development: Progress report, October 1, 1985-October 1, 1986

    SciTech Connect

    Fitzgerald, D.J.; DiStefano, S.; Rameshan, R.

    1986-12-01

    Objective is to use sputter-deposited amorphous metallic coatings on alloys in heat recovery systems in power plants. It was found that chromium could be used as a substitute for ruthenium in MoRuB. The new alloy, MoCrB, has corrosion current two orders of magnitude lower than MoRuB. The effort to develop the parameters for depositing FeCrPC on steel was frustrated by a persistent pinhole problem. Two titanium-based alloys were developed which are equal to or better than the optimized FeCrPC alloy in terms of corrosion resistance. The potentiodynamic polarization characteristics of MoCrB and TiCrBC were measured over a range in temperature from 25 to 100/sup 0/C. The corrosion current increased with temperature as predicted by theory. The corrosion characteristics of MoCrB and TiCrPC were also tested in 1.0N HC1. Cost analysis of the magnetron sputtering coating process indicates that the process cost is in the range of $2.50 to $3.00 per square foot steel.

  19. The effects of heat treatment and composition on the stress corrosion cracking resistance of inconel alloy X-750

    NASA Astrophysics Data System (ADS)

    Floreen, S.; Nelson, J. L.

    1983-01-01

    The stress corrosion cracking resistance of 24 heats of INCONEL* alloy X-750 was measured in high purity pH 10 water at 360 °C. An overaging heat treatment of 96 hours at 760 °C produced an improved combination of strength and cracking resistance because of the homogenization of slip in the matrix. Examination of residual elements showed that Zr additions further improved the cracking resistance by stabilizing theγ' precipitate in the grain boundary region. Combining the new heat treatment with the Zr addition produced approximately a 50 pct improvement in stress corrosion cracking resistance at a 10 pct lower yield strength.

  20. Mechanical and corrosion resistance properties of TiO2 nanoparticles reinforced Ni coating by electrodeposition

    NASA Astrophysics Data System (ADS)

    Shao, W.; Nabb, D.; Renevier, N.; Sherrington, I.; Luo, J. K.

    2012-09-01

    Coatings have been widely used in engineering and decoration to protect components and products and enhance their life span. Nickel (Ni) is one of the most important hard coatings. Improvement in its tribological and mechanical properties would greatly enhance its use in industry. Nanocomposite coatings of metals with various reinforced nanoparticles have been developed in last few decades. Titania (TiO2) exhibit excellent mechanical properties. It is believed that TiO2 incorporation in Ni matrix will improve the properties of Ni coatings significantly. The main purpose of the current work is to investigate the mechanical and anti-corrosion properties of the electroplated nickel nanocomposite with a small percentage of TiO2. The surface morphology of nanocomposite coating was characterized by scanning electron microscopy (SEM). The hardness of the nanocoating was carried out using micromaterials nanoplatform. The sliding wear rate of the coating at room temperature in dry condition was assessed by a reciprocating ball-on-disk computer-controlled oscillating tribotester. The results showed the nanocomposite coatings have a smoother and more compact surface than the pure Ni layer and have higher hardness and lower wear rate than the pure Ni coating. The anti-corrosion property of nanocomposite coating was carried out in 3.5% NaCl and high concentrated 35% NaCl solution, respectively. The results also showed that the nanocomposite coating improves the corrosion resistance significantly. This present work reveals that incorporation of TiO2 in nickel nanocomposite coating can achieve improved corrosion resistance and mechanical properties of both hardness and wear resistance performances, and the improvement becomes stronger as the content of TiO2 is increased.

  1. Electroless Ni-P-PTFE-Al2O3 Dispersion Nanocomposite Coating for Corrosion and Wear Resistance

    NASA Astrophysics Data System (ADS)

    Sharma, Ankita; Singh, A. K.

    2014-01-01

    With the aim to produce a coating having good corrosion and wear resistance alongside hardness but lesser friction coefficient, Ni-P-PTFE-Al2O3 (NiPPA) dispersion coating was developed. This was achieved by introducing nanosized polytetrafluoroethylene (PTFE) and alumina (Al2O3) in the Ni-P matrix deposited on mild steel substrate. The coating was characterized using scanning electron microscopy, energy dispersive analysis of x-ray, and x-ray diffractrometry. Microhardness and wear resistance of the coating was measured using Vicker's hardness tester and Pin-on-Disc method, respectively. The corrosion behavior was measured using electrochemical polarization and immersion tests with and without exposure in 3.5% NaCl solution. It is observed that codeposition of Al2O3 and PTFE particles with Ni-P coating results in comparatively smooth surface with nodular grains. The NiPPA coating was observed to have moderate hardness between electroless Ni-P-PTFE and Ni-P-Al2O3 coating and good wear resistance with lubricating effect. Addition of both PTFE and Al2O3 is observed to enhance corrosion resistance of the Ni-P coating. However, improvement in corrosion resistance is more due to addition of Al2O3 than PTFE. Continuous exposure for 10-20 days in corrosive solution is found to deteriorate corrosion protection properties of the coating.

  2. The influence of external factors on the corrosion resistance of high temperature superconductor thin films against moisture

    NASA Astrophysics Data System (ADS)

    Murugesan, M.; Obara, H.; Yamasaki, H.; Kosaka, S.

    2006-12-01

    High temperature superconductor (HTS) thin films have been systematically investigated for their corrosion resistance against moisture by studying the role of external factors such as temperature (T), relative humidity (RH), and the type of substrates in the corrosion. In general, (i) the corrosion is progressed monotonously with increasing T as well as RH, (ii) a threshold level of water vapor is needed to cause degradation, and (iii) between T and RH, the influence of T is more dominant. HTS films on SrTiO3 and CeO2 buffered sapphire (cbs) substrates showed better corrosion stability and a low rate of degradation in the critical current density as compared to that of the film grown on MgO substrate. Between DyBa2Cu3Oz (DBCO) and YBa2Cu3Oz, the former is reproducibly found to have many fold higher corrosion resistance against moisture. This observed enhancement in the corrosion resistance in DBCO could be explained by the improved microstructure in the films and the better lattice matching with the substrate. Thus, the dual advantage of DBCO/cbs films, i.e., the enhanced corrosion stability of DBCO and the appropriate dielectric properties of sapphire, can be readily exploited for the use of DBCO/cbs films in the microwave and power devices.

  3. Enhancement of seawater corrosion resistance in copper using acetone-derived graphene coating

    NASA Astrophysics Data System (ADS)

    Huh, Jae-Hoon; Kim, Seung Hyun; Chu, Jae Hwan; Kim, Sung Youb; Kim, Ji Hyun; Kwon, Soon-Yong

    2014-03-01

    We show that acetone-derived graphene coating can effectively enhance the corrosion efficiency of copper (Cu) in a seawater environment (0.5-0.6 M (~3.0-3.5%) sodium chloride). By applying a drop of acetone (~20 μl cm-2) on Cu surfaces, rapid thermal annealing allows the facile and rapid synthesis of graphene films on Cu surfaces with a monolayer coverage of almost close to ~100%. Under optimal growth conditions, acetone-derived graphene is found to have a relatively high crystallinity, comparable to common graphene grown by chemical vapor deposition. The resulting graphene-coated Cu surface exhibits 37.5 times higher corrosion resistance as compared to that of mechanically polished Cu. Further, investigation on the role of graphene coating on Cu surfaces suggests that the outstanding corrosion inhibition efficiency (IE) of 97.4% is obtained by protecting the underlying Cu against the penetration of both dissolved oxygen and chlorine ions, thanks to the closely spaced atomic structure of the graphene sheets. The increase of graphene coating thickness results in the enhancement of the overall corrosion IE up to ~99%, which can be attributed to the effective blocking of the ionic diffusion process via grain boundaries. Overall, our results suggest that the acetone-derived graphene film can effectively serve as a corrosion-inhibiting coating in the seawater level and that it may have a promising role to play for potential offshore coating.We show that acetone-derived graphene coating can effectively enhance the corrosion efficiency of copper (Cu) in a seawater environment (0.5-0.6 M (~3.0-3.5%) sodium chloride). By applying a drop of acetone (~20 μl cm-2) on Cu surfaces, rapid thermal annealing allows the facile and rapid synthesis of graphene films on Cu surfaces with a monolayer coverage of almost close to ~100%. Under optimal growth conditions, acetone-derived graphene is found to have a relatively high crystallinity, comparable to common graphene grown by

  4. Corrosion resistance of biodegradable polymeric layer-by-layer coatings on magnesium alloy AZ31

    NASA Astrophysics Data System (ADS)

    Cui, Lan-Yue; Zeng, Rong-Chang; Zhu, Xiao-Xiao; Pang, Ting-Ting; Li, Shuo-Qi; Zhang, Fen

    2016-06-01

    Biocompatible polyelectrolyte multilayers (PEMs) and polysiloxane hybrid coatings were prepared to improve the corrosion resistance of biodegradable Mg alloy AZ31. The PEMs, which contained alternating poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH), were first self-assembled on the surface of the AZ31 alloy substrate via electrostatic interactions, designated as (PAH/PSS)5/AZ31. Then, the (PAH/PSS)5/AZ31 samples were dipped into a methyltrimethoxysilane (MTMS) solution to fabricate the PMTMS films, designated as PMTMS/(PAH/PSS)5/AZ31. The surface morphologies, microstructures and chemical compositions of the films were investigated by FE-SEM, FTIR, XRD and XPS. Potentiodynamic polarization, electrochemical impedance spectroscopy and hydrogen evolution measurements demonstrated that the PMTMS/(PAH/PSS)5/AZ31 composite film significantly enhanced the corrosion resistance of the AZ31 alloy in Hank's balanced salt solution (HBSS). The PAH and PSS films effectively improved the deposition of Ca-P compounds including Ca3(PO4)2 and hydroxyapatite (HA). Moreover, the corrosion mechanism of the composite coating was discussed. These coatings could be an alternative candidate coating for biodegradable Mg alloys.

  5. Preparation and corrosion resistance of pulse electrodeposited Zn and Zn-SiC nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Sajjadnejad, M.; Mozafari, A.; Omidvar, H.; Javanbakht, M.

    2014-05-01

    Pure Zn and Zn matrix composite coatings containing nano-sized SiC particles with an average size of 50 nm were prepared from the zinc sulfate bath. The effects of the pulse frequency, maximum current density and duty cycle on the amount of particles embedded were examined. Electron microscopic studies revealed that the coating morphology was modified by the presence of SiC nanoparticles. In the presence of SiC nanoparticles deposit grows in outgrowth mode resulting in a very rough and porous microstructure. However, at very low and very high duty cycles a smooth and pore free microstructure was obtained. Corrosion resistance properties of the coatings were studied using potentiodynamic polarization technique in 1 M NaCl solution. It was established that presence of well-dispersed nanoparticles significantly improves corrosion resistance of the zinc by filling gaps and defects between zinc flakes and leading to a smoother surface. However, presence of the SiC nanoparticles led to a mixed microstructure with fine and coarse zinc flakes in some coatings, which presented a weak corrosion behavior. Incorporation of SiC nanoparticles enhanced hardness of the Zn coatings by fining deposit structure and through the dispersion hardening effect.

  6. Evaluation of the stress corrosion cracking resistance of several high strength low alloy steels

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Nelson, E. E.

    1980-01-01

    The stress corrosion cracking resistance was studied for high strength alloy steels 4130, 4340, for H-11 at selected strength levels, and for D6AC and HY140 at a single strength. Round tensile and C-ring type specimens were stressed up to 100 percent of their yield strengths and exposed to alternate immersion in salt water, salt spray, the atmosphere at Marshall Space Flight Center, and the seacoast at Kennedy Space Center. Under the test conditions, 4130 and 4340 steels heat treated to a tensile strength of 1240 MPa (180 ksi), H-11 and D6AC heat treated to a tensile strength of 1450 MPa (210 ksi), and HY140 (1020 MPa, 148 ksi) are resistant to stress corrosion cracking because failures were not encountered at stress levels up to 75 percent of their yield strengths. A maximum exposure period of one month for alternate immersion in salt water or salt spray and three months for seacoast is indicated for alloy steel to avoid false indications of stress corrosion cracking because of failure resulting from severe pitting.

  7. The Effect of Surface Patterning on Corrosion Resistance of Biomedical Devices

    NASA Astrophysics Data System (ADS)

    Guo, Mengnan; Toloei, Alisina; Rotermund, Harm H.

    2016-10-01

    In this study, two styles of surface topographies have been created on stainless steel wires to test their corrosion resistance as simulated implanted biomedical devices. Grade 316 LVM stainless steel wire was initially polished to G1500 surface finish before treatment to produce the two different topographies: 1. Unidirectional roughness was created using SiC papers and 2. Various patterns were created with specific hole diameter and inter-hole spacing using focused ion beam (FIB). In order to simulate the environment of implanted biomedical devices, a three-electrode electrochemical cell with 0.9% (by mass) NaCl solution has been used to test the corrosion resistance of the samples by potentiodynamic polarization test method. SEM and EDS analyzed the appearance and chemical composition of different elements including oxygen on the surface. The potential of stable pitting, time related to the initiation of the stable pitting, and the highest corrosion current associated with stable pitting have been compared for samples with the two styles of topography. It was found that surfaces with patterns have a relatively higher pitting potential and it takes longer time to initiate stable pitting than the surface without any patterns.

  8. The effect of strain hardening on resistance to electrochemical corrosion of wires for orthopaedics

    NASA Astrophysics Data System (ADS)

    Przondziono, J.; Walke, W.; Hadasik, E.; Szymszal, J.

    2012-05-01

    The purpose of this research is to evaluate electrochemical corrosion resistance of wire with modified surface, made of stainless steel of Cr-Ni-Mo type, widely used in implants for orthopaedics, depending on hardening created in the process of drawing. Tests have been carried out in the environment imitating human osseous tissue. Pitting corrosion was determined on the ground of registered anodic polarisation curves by means of potentiodynamic method with application of electrochemical testing system VoltaLab® PGP 201. Wire corrosion tests were carried out in Tyrode solution on samples that were electrochemically polished as well as electrochemically polished and finally chemically passivated. Initial material for tests was wire rod made of X2CrNiMo17-12-2 steel with diameter of 5.5 mm in supersaturated condition. Wire rod was drawn up to diameter of 1.35 mm. This work shows the course of flow curve of wire made of this grade of steel and mathematical form of yield stress function. The study also presents exemplary curves showing the dependence of polarisation resistance in strain function in the drawing process of electrochemically passivated and electrochemically polished and then chemically passivated wire.

  9. Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

    NASA Astrophysics Data System (ADS)

    Dhandapani, Vishnu Shankar; Subbiah, Ramesh; Thangavel, Elangovan; Arumugam, Madhankumar; Park, Kwideok; Gasem, Zuhair M.; Veeraragavan, Veeravazhuthi; Kim, Dae-Eun

    2016-05-01

    Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33 at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77 at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

  10. Cluster formula of Fe-containing Monel alloys with high corrosion-resistance

    SciTech Connect

    Li Baozeng; Gu Junjie; Wang Qing; Ji Chunjun; Wang Yingmin; Qiang Jianbing; Dong Chuang

    2012-06-15

    The cluster-plus-glue-atom model is applied in the composition interpretation of Monel alloys. This model considers ideal atomic nearest neighbor configurations among the constituent elements and has been used in understanding compositions of complex alloys like quasicrystals, amorphous alloys, and cupronickels. According to this model, any structure can be expressed by cluster formula [cluster](glue atom){sub x}, x denoting the number of glue atoms matching one cluster. According to this model, two groups of experimental composition series [Fe{sub 1}Ni{sub 12}]Cu{sub x} and [Fe{sub y}Ni{sub 12}]Cu{sub 5} were designed which fell close to conventional Fe-containing Monel alloys. The designed alloys after solution treatment plus water quenching, are monolithic FCC Ni-based solid solutions. Among them, the [Fe{sub 1}Ni{sub 12}]Cu{sub 5} alloy has the highest corrosion resistance in simulated sea water, and its performance is superior to that of industrial Monel 400 alloy. - Highlights: Black-Right-Pointing-Pointer A stable solid solution model is proposed using our 'cluster-plus-glue-atom model'. Black-Right-Pointing-Pointer This model is used to develop Monel corrosion resistant alloys. Black-Right-Pointing-Pointer Single FCC structure is easily retained. Black-Right-Pointing-Pointer The alloys show good corrosion properties. Black-Right-Pointing-Pointer This work contributes to the general understanding of engineering alloys.

  11. PPM-based System for Guided Waves Communication Through Corrosion Resistant Multi-wire Cables

    NASA Astrophysics Data System (ADS)

    Trane, G.; Mijarez, R.; Guevara, R.; Pascacio, D.

    Novel wireless communication channels are a necessity in applications surrounded by harsh environments, for instance down-hole oil reservoirs. Traditional radio frequency (RF) communication schemes are not capable of transmitting signals through metal enclosures surrounded by corrosive gases and liquids. As an alternative to RF, a pulse position modulation (PPM) guided waves communication system has been developed and evaluated using a corrosion resistant 4H18 multi-wire cable, commonly used to descend electronic gauges in down-hole oil applications, as the communication medium. The system consists of a transmitter and a receiver that utilizes a PZT crystal, for electrical/mechanical coupling, attached to each extreme of the multi-wire cable. The modulator is based on a microcontroller, which transmits60 kHz guided wave pulses, and the demodulator is based on a commercial digital signal processor (DSP) module that performs real time DSP algorithms. Experimental results are presented, which were obtained using a 1m corrosion resistant 4H18multi-wire cable, commonly used with downhole electronic gauges in the oil sector. Although there was significant dispersion and multiple mode excitations of the transmitted guided wave energy pulses, the results show that data rates on the order of 500 bits per second are readily available employing PPM and simple communications techniques.

  12. Microstructure and Corrosion Resistance of Laser Additively Manufactured 316L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Trelewicz, Jason R.; Halada, Gary P.; Donaldson, Olivia K.; Manogharan, Guha

    2016-03-01

    Additive manufacturing (AM) of metal alloys to produce complex part designs via powder bed fusion methods such as laser melting promises to be a transformative technology for advanced materials processing. However, effective implementation of AM processes requires a clear understanding of the processing-structure-properties-performance relationships in fabricated components. In this study, we report on the formation of micro and nanoscale structures in 316L stainless steel samples printed by laser AM and their implications for general corrosion resistance. A variety of techniques including x-ray diffraction, optical, scanning and transmission electron microscopy, x-ray fluorescence, and energy dispersive x-ray spectroscopy were employed to characterize the microstructure and chemistry of the laser additively manufactured 316L stainless steel, which are compared with wrought 316L coupons via electrochemical polarization. Apparent segregation of Mo has been found to contribute to a loss of passivity and an increased anodic current density. While porosity will also likely impact the environmental performance (e.g., facilitating crevice corrosion) of AM alloys, this work demonstrates the critical influence of microstructure and heterogeneous solute distributions on the corrosion resistance of laser additively manufactured 316L stainless steel.

  13. Hierarchically ordered self-lubricating superhydrophobic anodized aluminum surfaces with enhanced corrosion resistance.

    PubMed

    Vengatesh, Panneerselvam; Kulandainathan, Manickam Anbu

    2015-01-28

    Herein, we report a facile method for the fabrication of self-lubricating superhydrophobic hierarchical anodic aluminum oxide (AAO) surfaces with improved corrosion protection, which is greatly anticipated to have a high impact in catalysis, aerospace, and the shipping industries. This method involves chemical grafting of as-formed AAO using low surface free energy molecules like long chain saturated fatty acids, perfluorinated fatty acid (perfluorooctadecanoic acid, PFODA), and perfluorosulfonicacid-polytetrafluoroethylene copolymer. The pre and post treatment processes in the anodization of aluminum (Al) play a vital role in the grafting of fatty acids. Wettability and surface free energy were analyzed using a contact angle meter and achieved 161.5° for PFODA grafted anodized aluminum (PFODA-Al). This study was also aimed at evaluating the surface for corrosion resistance by Tafel polarization and self-lubricating properties by tribological studies using a pin-on-disc tribometer. The collective results showed that chemically grafted AAO nanostructures exhibit high corrosion resistance toward seawater and low frictional coefficient due to low surface energy and self-lubricating property of fatty acids covalently linked to anodized Al surfaces.

  14. Atomic-scale decoration for improving the pitting corrosion resistance of austenitic stainless steels

    PubMed Central

    Zhou, Y. T.; Zhang, B.; Zheng, S. J.; Wang, J.; San, X. Y.; Ma, X. L.

    2014-01-01

    Stainless steels are susceptible to the localized pitting corrosion that leads to a huge loss to our society. Studies in the past decades confirmed that the pitting events generally originate from the local dissolution in MnS inclusions which are more or less ubiquitous in stainless steels. Although a recent study indicated that endogenous MnCr2O4 nano-octahedra within the MnS medium give rise to local nano-galvanic cells which are responsible for the preferential dissolution of MnS, effective solutions of restraining the cells from viewpoint of electrochemistry are being tantalizingly searched. Here we report such a galvanic corrosion can be greatly resisted via bathing the steels in Cu2+-containing solutions. This chemical bath generates Cu2−δS layers on the surfaces of MnS inclusions, invalidating the nano-galvanic cells. Our study provides a low-cost approach via an atomic scale decoration to improve the pitting corrosion resistance of stainless steels in a volume-treated manner. PMID:24398863

  15. Welding duplex stainless steels for maximum corrosion resistance in chemical process industry applications

    SciTech Connect

    Gooch, T.G.; Gunn, R.N.

    1994-12-31

    Fabrication of process plant, pipework etc in ferritic-austenitic steels commonly entails fusion welding. The weld thermal cycle can significantly influence material corrosion behavior and hence service performance. The paper reviews the situation, with emphasis on arc welding as most commonly employed by industry. An outline is given of the major metallurgical changes due to welding which take place in the heat affected zone in base steel and in the fused weld metal. The weld thermal cycle experienced alters the ferrite/austenite structure from that in the parent material, and can induce intermetallic precipitation. Nitrogen may also be lost from the weld metal. These changes affect corrosion resistance, and must be controlled to achieve optimum service properties. The consequences of surface oxidation in the weld area and of local residual stresses are also considered, and it is pointed out that resistance to stress corrosion cracking in chloride or sour, H{sub 2}S media is dependent on ferrite/austenite balance. The main factors in formulating a welding procedure are described. Depending on the material composition and joint heat sink, arc energy should be held between minimum and maximum levels to promote adequate austenite formation in the weld area without inducing intermetallic formation. Nitrogen loss should be minimized, and adequate filler should be added: slight overalloying of the consumable is preferred, provided that intermetallic precipitation is avoided.

  16. Effect of microstructure on the corrosion and deformation behavior of a newly developed 6Mn-5Cr-1.5Cu corrosion-resistant white iron

    NASA Astrophysics Data System (ADS)

    Rao, P. N. V. R. S. S. V. Prasada; Patwardhan, A. K.; Jain, N. C.

    1993-02-01

    An experimental study has been made of the effect of heat treatment on the transformation behavior of a 4.8 pct Cr white iron, alloyed with 6 pct Mn and 1.5 pct Cu, by employing optical metallography, X-ray diffractometry, and differential thermal analysis (DTA) techniques, with a view to assess the suitability of the different microstructures in resisting aqueous corrosion. The matrix microstructure in the as-cast condition, comprising pearlite + bainite/martensite, transformed to austenite on heat-treating at all the temperatures between 900 °C and 1050 °C. Increasing the soaking period at each of the heat-treating temperatures led to an increase in the volume fraction and stability of austenite. M3C was the dominant carbide present in the as-cast condition. On heat-treating, different carbides formed: M23C6 carbide was present on heat-treating at 900 °C and 950 °C; on heat-treating at 1000 °C, M7C3 formed and persisted even on heattreating at 1050 °C. The possible formation of M5C2 carbide in the as-cast and heat-treated conditions (900 °C and 950 °C) is also indicated. Dispersed carbides (DC), present in austenite up to 950 °C, mostly comprised M3C and M5C2. On stress relieving of the heat-treated samples, M7C3-type DC also formed. The hardness changes were found to be consistent with the micro-structural changes occurring on heat-treating. The as-cast state was characterized by a reasonable resistance to corrosion in 5 pct NaCl solution. On heat-treating, the corrosion resistance improved over that in the as-cast state. After 4 hours soaking, increasing the temperature from 900 °C to 1050 °C led to an improvement in corrosion resistance. However, after 10 hours soaking, corrosion resistance decreased on increasing the temperature from 900 °C to 950 °C and improved thereafter on increasing the heat-treating temperature. Deformation behavior responded to the microstructure on similar lines as the corrosion behavior. Although in an early stage of

  17. Characterization of an alkali- and halide-resistant laccase expressed in E. coli: CotA from Bacillus clausii.

    PubMed

    Brander, Søren; Mikkelsen, Jørn D; Kepp, Kasper P

    2014-01-01

    The limitations of fungal laccases at higher pH and salt concentrations have intensified the search for new extremophilic bacterial laccases. We report the cloning, expression, and characterization of the bacterial cotA from Bacillus clausii, a supposed alkalophilic ortholog of cotA from B. subtilis. Both laccases were expressed in E. coli strain BL21(DE3) and characterized fully in parallel for strict benchmarking. We report activity on ABTS, SGZ, DMP, caffeic acid, promazine, phenyl hydrazine, tannic acid, and bilirubin at variable pH. Whereas ABTS, promazine, and phenyl hydrazine activities vs. pH were similar, the activity of B. clausii cotA was shifted upwards by ~0.5-2 pH units for the simple phenolic substrates DMP, SGZ, and caffeic acid. This shift is not due to substrate affinity (K(M)) but to pH dependence of catalytic turnover: The k(cat) of B. clausii cotA was 1 s⁻¹ at pH 6 and 5 s⁻¹ at pH 8 in contrast to 6 s⁻¹ at pH 6 and 2 s⁻¹ at pH 8 for of B. subtilis cotA. Overall, k(cat)/K(M) was 10-fold higher for B. subtilis cotA at pH(opt). While both proteins were heat activated, activation increased with pH and was larger in cotA from B. clausii. NaCl inhibited activity at acidic pH, but not up to 500-700 mM NaCl in alkaline pH, a further advantage of the alkali regime in laccase applications. The B. clausii cotA had ~20 minutes half-life at 80°C, less than the ~50 minutes at 80°C for cotA from B. subtilis. While cotA from B. subtilis had optimal stability at pH~8, the cotA from B. clausii displayed higher combined salt- and alkali-resistance. This resistance is possibly caused by two substitutions (S427Q and V110E) that could repel anions to reduce anion-copper interactions at the expense of catalytic proficiency, a trade-off of potential relevance to laccase optimization.

  18. Characterization of an Alkali- and Halide-Resistant Laccase Expressed in E. coli: CotA from Bacillus clausii

    PubMed Central

    Brander, Søren; Mikkelsen, Jørn D.; Kepp, Kasper P.

    2014-01-01

    The limitations of fungal laccases at higher pH and salt concentrations have intensified the search for new extremophilic bacterial laccases. We report the cloning, expression, and characterization of the bacterial cotA from Bacillus clausii, a supposed alkalophilic ortholog of cotA from B. subtilis. Both laccases were expressed in E. coli strain BL21(DE3) and characterized fully in parallel for strict benchmarking. We report activity on ABTS, SGZ, DMP, caffeic acid, promazine, phenyl hydrazine, tannic acid, and bilirubin at variable pH. Whereas ABTS, promazine, and phenyl hydrazine activities vs. pH were similar, the activity of B. clausii cotA was shifted upwards by ∼0.5–2 pH units for the simple phenolic substrates DMP, SGZ, and caffeic acid. This shift is not due to substrate affinity (KM) but to pH dependence of catalytic turnover: The kcat of B. clausii cotA was 1 s−1 at pH 6 and 5 s−1 at pH 8 in contrast to 6 s−1 at pH 6 and 2 s−1 at pH 8 for of B. subtilis cotA. Overall, kcat/KM was 10-fold higher for B. subtilis cotA at pHopt. While both proteins were heat activated, activation increased with pH and was larger in cotA from B. clausii. NaCl inhibited activity at acidic pH, but not up to 500–700 mM NaCl in alkaline pH, a further advantage of the alkali regime in laccase applications. The B. clausii cotA had ∼20 minutes half-life at 80°C, less than the ∼50 minutes at 80°C for cotA from B. subtilis. While cotA from B. subtilis had optimal stability at pH∼8, the cotA from B. clausii displayed higher combined salt- and alkali-resistance. This resistance is possibly caused by two substitutions (S427Q and V110E) that could repel anions to reduce anion-copper interactions at the expense of catalytic proficiency, a trade-off of potential relevance to laccase optimization. PMID:24915287

  19. Stabilization/solidification of hazardous and radioactive wastes with alkali-activated cements.

    PubMed

    Shi, Caijun; Fernández-Jiménez, A

    2006-10-11

    This paper reviews progresses on the use of alkali-activated cements for stabilization/solidification of hazardous and radioactive wastes. Alkali-activated cements consist of an alkaline activator and cementing components, such as blast furnace slag, coal fly ash, phosphorus slag, steel slag, metakaolin, etc., or a combination of two or more of them. Properly designed alkali-activated cements can exhibit both higher early and later strengths than conventional portland cement. The main hydration product of alkali-activated cements is calcium silicate hydrate (CSH) with low Ca/Si ratios or aluminosilicate gel at room temperature; CSH, tobmorite, xonotlite and/or zeolites under hydrothermal condition, no metastable crystalline compounds such as Ca(OH)(2) and calcium sulphoaluminates exist. Alkali-activated cements also exhibit excellent resistance to corrosive environments. The leachability of contaminants from alkali-activated cement stabilized hazardous and radioactive wastes is lower than that from hardened portland cement stabilized wastes. From all these aspects, it is concluded that alkali-activated cements are better matrix for solidification/stabilization of hazardous and radioactive wastes than Portland cement.

  20. Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics

    NASA Astrophysics Data System (ADS)

    Ming, Miao Yi; Jiang, Xiaohong; Piliptsou, D. G.; Zhuang, Yuzhao; Rogachev, A. V.; Rudenkov, A. S.; Balmakou, A.

    2016-08-01

    To improve structural, mechanical and chemical properties of diamond-like carbon films, we developed amorphous carbon chromium-modified composite films fabricated by means of cathode magnetic filtered arc deposition. The properties were analyzed by Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy for the purpose of the structure characterization, elemental analysis and topology examination. Moreover, we also assessed residual stress, the coefficient of friction, hardness, the elastic modulus and corrosion parameters through X-ray double-crystal surface profilometry, tribo-testing, nanoindenter-testing, as well as contact angle measurements and potentiodynamic polarization analysis. As a result of a comparative analysis, we revealed a substantial improvement in the characteristics of developed composite films in comparison with amorphous carbon films. For example, Cr-modification is resulted, in greater integrated performance, toughness and corrosion resistance; the residual stress was reduced substantially.

  1. Improving intergranular corrosion resistance of sensitized type 316 austenitic stainless steel by laser surface melting

    NASA Astrophysics Data System (ADS)

    Mudali, U. K.; Dayal, R. K.

    1992-06-01

    An attempt was made to modify the surface microstructure of a sensitized austenitic stainless steel, without affecting the bulk properties, using laser surface melting techniques. AISI type 316 stainless steel specimens sensitized at 923 K for 20 hr were laser surface melted using a pulsed ruby laser at 6 J energy. Two successive pulses were given to ensure uniform melting and homogenization. The melted layers were characterized by small angle X- ray diffraction and scanning electron microscopy. Intergranular corrosion tests were carried out on the melted region as per ASTM A262 practice A (etch test) and electrochemical potentiokinetic reactivation test. The results indicated an improvement in the intergranular corrosion resistance after laser surface melting. The results are explained on the basis of homogeneous and nonsensitized microstructure obtained at the surface after laser surface melting. It is concluded that laser surface melting can be used as an in situ method to increase the life of a sensitized component by modifying the surface microstructure.

  2. Development of coatings with improved corrosion resistance in sulfur-containing environments

    SciTech Connect

    Natesan, K. ); Johnson, R.N. )

    1990-01-01

    Corrosion of metallic structure materials at elevated temperatures in complex multicomponent gas environments is a potential problem in many fossil energy systems, especially those using coal as a feedstock. The use of appropriate corrosion-resistant coatings on metallic components can minimize material degradation and extend component life. In the present study, the chemical compatibility of a number of coatings is examined by exposing them to simulated oxygen/sulfur mixed-gas environments at metal temperatures of 500 and 650{degree}C. Coatings were developed via pack cementation and electrospark deposition techniques on T22 and T91 substrates. The oxidation/sulfidation test results for the coated specimens were compared with those for the uncoated alloys and for high-chromium structural alloys of interest in fossil energy applications. Coatings tested were Fe--Cr--Mo. Alloys tested include nickel base, nickel, and chromium alloys, and stainless steel 310. 5 refs., 12 figs., 2 tabs.

  3. Chlor-alkali plant contamination of Aussa River sediments induced a large Hg-resistant bacterial community

    NASA Astrophysics Data System (ADS)

    Baldi, Franco; Marchetto, Davide; Gallo, Michele; Fani, Renato; Maida, Isabel; Covelli, Stefano; Fajon, Vesna; Zizek, Suzana; Hines, Mark; Horvat, Milena

    2012-11-01

    A closed chlor-alkali plant (CAP) discharged Hg for decades into the Aussa River, which flows into Marano Lagoon, resulting in the large-scale pollution of the lagoon. In order to get information on the role of bacteria as mercury detoxifying agents, analyses of anions in the superficial part (0-1 cm) of sediments were conducted at four stations in the Aussa River. In addition, measurements of biopolymeric carbon (BPC) as a sum of the carbon equivalent of proteins (PRT), lipids (LIP), and carbohydrates (CHO) were performed to correlate with bacterial biomass such as the number of aerobic heterotrophic cultivable bacteria and their percentage of Hg-resistant bacteria. All these parameters were used to assess the bioavailable Hg fraction in sediments and the potential detoxification activity of bacteria. In addition, fifteen isolates were characterized by a combination of molecular techniques, which permitted their assignment into six different genera. Four out of fifteen were Gram negative with two strains of Stenotrophomonas maltophilia, one Enterobacter sp., and one strain of Brevibacterium frigoritolerans. The remaining strains (11) were Gram positive belonging to the genera Bacillus and Staphylococcus. We found merA genes in only a few isolates. Mercury volatilization from added HgCl2 and the presence of plasmids with the merA gene were also used to confirm Hg reductase activity. We found the highest number of aerobic heterotrophic Hg-resistant bacteria (one order magnitude higher) and the highest number of Hg-resistant species (11 species out of 15) at the confluence of the River Aussa and Banduzzi's channel, which transport Hg from the CAP, suggesting that Hg is strongly detoxified [reduced to Hg(0)] at this location.

  4. Surface modifications of steels to improve corrosion resistance in sulfidizing-oxidizing environments

    NASA Astrophysics Data System (ADS)

    Behrani, Vikas

    Industrial and power generation processes employ units like boilers and gasifiers to burn sulfur containing fuels to produce steam and syn gas (H 2 and CO), which can generate electricity using turbines and fuel cells. These units often operate under environments containing gases such as H 2S, SO2, O2 etc, which can attack the metallic structure and impose serious problems of corrosion. Corrosion control in high temperature sulfur bearing environments is a challenging problem requiring information on local gaseous species at the surface of alloy and mechanisms of degradation in these environments. Coatings have proved to be a better alternative for improving corrosion resistance without compromising the bulk mechanical properties. Changes in process conditions may result in thermal and/or environment cycling between oxidizing and sulfidizing environments at the alloy surface, which can damage the protective scale formed on the alloy surface, leading to increase in corrosion rates. Objective of this study was to understand the effect of fluctuating environments on corrosion kinetics of carbon steels and develop diffusion based coatings to mitigate the high temperatures corrosion under these conditions. More specifically, the focus was: (1) to characterize the local gaseous environments at the surface of alloys in boilers; (2) optimizing diffusion coatings parameters for carbon steel; (3) understand the underlying failure mechanisms in cyclic environments; (4) to improve aluminide coating behavior by co-deposition of reactive elements such as Yttrium and Hafnium; (5) to formulate a plausible mechanism of coating growth and effects of alloying elements on corrosion; and (6) to understand the spallation behavior of scale by measuring stresses in the scales. The understanding of coating mechanism and effects of fluctuating gaseous environments provides information for designing materials with more reliable performance. The study also investigates the mechanism behind

  5. DIFFUSION COATINGS FOR CORROSION RESISTANT COMPONENTS IN COAL GASIFICATION SYSTEMS

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Esperanza Alvarez; Kai-Hung Lau; Angel Sanjurjo

    2005-01-01

    Heat-exchangers, particle filters, turbines, and other components in integrated coal gasification combined cycle system must withstand the highly sulfiding conditions of the high temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy may improve is resistance to such sulfidation attack and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. During this reporting period we coated coupons of selected alloy steels with diffusion coatings of Cr and Al, as well as with titanium and tantalum nitrides. The coated samples were analyzed for their surface composition. In several instances, the samples were also cut to determine the depth profile of the coating. Several of the early runs did not yield uniform or deep enough coatings and hence a significant portion of the effort in this period was devoted fixing the problems with our fluidized bed reactor. Before the end of the quarter we had prepared a number of samples, many of them in duplicates, and sent one set to Wabash River Energy Laboratory for them to install in their gasifier. The gasifier was undergoing a scheduled maintenance and thus presented an opportunity to place some of our coupons in the stream of an operating gasifier. The samples submitted included coated and uncoated pairs of different alloys.

  6. Deformation behavior, corrosion resistance, and cytotoxicity of Ni-free Zr-based bulk metallic glasses.

    PubMed

    Liu, L; Qiu, C L; Chen, Q; Chan, K C; Zhang, S M

    2008-07-01

    Two Ni-free bulk metallic glasses (BMGs) of Zr(60)Nb(5)Cu(22.5)Pd(5)Al(7.5) and Zr(60)Nb(5)Cu(20)Fe(5)Al(10) were successfully prepared by arc-melting and copper mold casting. The thermal stability and crystallization were studied using differential scanning calorimetry. It demonstrates that the two BMGs exhibit very good glass forming ability with a wide supercooled liquid region. A multi-step process of crystallization with a preferential formation of quasicrystals occurred in both BMGs under continuous heating. The deformation behavior of the two BMGs was investigated using quasi-static compression testing. It reveals that the BMGs exhibit not only superior strength but also an extended plasticity. Corrosion behaviors of the BMGs were investigated in phosphate buffered solution by electrochemical polarization. The result shows that the two BMGs exhibit excellent corrosion resistance characterized by low corrosion current densities and wide passive regions. X-ray photoelectron spectroscopy analysis revealed that the passive film formed after anodic polarization was highly enriched in zirconium, niobium, and aluminum oxides. This is attributed to the excellent corrosion resistance. Additionally, the potential cytotoxicity of the two Ni-free BMGs was evaluated through cell culture for 1 week followed by 3-(4,5-Dimethylthiazol-2-yl-)-2,5-diphenyltetrazolium bromide assay and SEM observation. The results indicate that the two Ni-free BMGs exhibit as good biocompatibility as Ti-6Al-4V alloy, and thus show a promising potential for biomedical applications.

  7. Effects of surface topography and vibrations on wetting: Superhydrophobicity, icephobicity and corrosion resistance

    NASA Astrophysics Data System (ADS)

    Ramachandran, Rahul

    Concrete and metallic materials are widely used in construction and water industry. The interaction of both these materials with water and ice (or snow) produces undesirable results and is therefore of interest. Water that gets absorbed into the pores of dry concrete expands on freezing and can lead to crack formation. Also, the ice accretion on concrete surfaces such as roadways can have disastrous consequence. Metallic components used in the water industry undergo corrosion due to contact with aqueous corrosive solutions. Therefore, it is desirable to make concrete water/ice-repellent, and to make metallic surfaces corrosion-resistant. Recent advances in micro/nanotechnology have made it possible to design functional micro/nanostructured surfaces with micro/nanotopography providing low adhesion. Some examples of such surfaces are superhydrophobic surfaces, which are extremely water repellent, and icephobic surfaces, which have low ice adhesion, repel incoming water droplets before freezing, or delay ice nucleation. This dissertation investigates the effects of surface micro/nanotopography and small amplitude fast vibrations on the wetting and adhesion of concrete with the goal of producing hydrophobic and icephobic concrete, and on the wetting of metallic surfaces to prevent corrosion. The relationship between surface micro/nanotopography and small fast vibrations is established using the method of separation of motions. Both these small scale effects can be substituted by an effective force or energy. The structure-property relationships in materials and surfaces are established. Both vibrations as well as surface micro/nanopatterns can affect wetting properties such as contact angle and surface free energy. Hydrophobic engineered cementitious composite samples are produced by controlling their surface topography and surface free energy. The surface topography is controlled by varying the concrete mixture composition. The surface free energy of concrete is

  8. Development of oxidation/corrosion-resistant composite materials and interfaces

    SciTech Connect

    Stinton, D.P.; Besmann, T.M.; Shanmugham, S.

    1995-06-01

    Continuous fiber ceramic composites (CFCCs) are being developed for high temperature structural applications, many of which are in oxidative environments. Such composites are attractive since they are light-weight and possess the desired mechanical properties at elevated temperature and in aggressive environments. The most significant advantage is their toughness and their non-catastrophic failure behavior. The mechanical properties of CFCCs have been characteristically linked with the nature of the interfacial bond between the fibers and the matrix. Weakly bonded fiber-matrix intefaces allow an impinging matrix crack to be deflected such that the fracture process occurs through several stages: Crack deflection, debonding at the interface, fiber slip and pull-out, and ultimately fiber failure. Such a composite will fail in a graceful manner and exhibit substantial fracture toughness. Currently, carbon interface coatings are used to appropriately tailor interface properties, however their poor oxidation resistance has required a search of an appropriate replacement. Generally, metal oxides are inherently stable to oxidation and possess thermal expansion coefficients relatively close to those of Nicalon and SiC. However, the metal oxides must also be chemically compatible with the fiber and matrix. If the fiber/interface/matrix system is chemically compatible, then the interfacial bonding stress is influenced by the thermal residual stresses that are generated as the composite is cooled from processing to room temperature. In the current work, thermomechanical computational results were obtained from a finite element model (FEM) for calculating the thermal residual stresses. This was followed by experimental evaluation of Nicalon/SiC composites with carbon, alumina, and mullite interfacial coatings.

  9. Characterization and Evaluation of Cyclic Hot Corrosion Resistance of Detonation-Gun Sprayed Ni-5Al Coatings on Inconel-718

    NASA Astrophysics Data System (ADS)

    Saladi, Sekar; Menghani, Jyoti V.; Prakash, Satya

    2015-06-01

    The high temperature hot corrosion behavior of bare and detonation-gun-sprayed Ni-5Al coatings on Ni-based superalloy Inconel-718 is comparatively discussed in the present study. Hot corrosion studies were carried out at 900 °C for 100 cycles in Na2SO4-60% V2O5 molten salt environment under cyclic heating and cooling conditions. The thermo-gravimetric technique was used to establish the kinetics of hot corrosion. X-ray diffraction, SEM/EDAX, and X-ray mapping techniques were used to analyze the hot corrosion products of bare and coated superalloys. The results indicate that Ni-5Al-coated superalloy showed very good hot corrosion resistance. The overall weight gain and parabolic rate constant of Ni-5Al-coated superalloy were less in comparison with the bare superalloy. The D-gun-sprayed Ni-5Al coating was found to be uniform, adherent, and dense in hot corrosion environment. The formation of nickel- and aluminum-rich oxide scale might have contributed for the better hot corrosion resistance of the coated superalloy.

  10. Preparation and testing of corrosion and spallation-resistant coatings

    SciTech Connect

    Hurley, John

    2012-09-30

    This Energy & Environmental Research Center (EERC) project is designed to determine if plating APMT, a specific highly oxidation-resistant oxide dispersion-strengthened FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The method for joining the APMT plate to the superalloys is called evaporative metal bonding. It involves placing a thin foil of zinc (Zn) between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the Zn melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The Zn then diffuses through the alloys and evaporates from their surfaces. Laboratory testing has shown that the diffusion rate of Zn through the FeCrAl alloy is much faster than through the nickel superalloys. This means that the FeCrAl will serve as a sink for the Zn bonding alloy during the evaporative metal bonding process. Also, the testing has shown that the Zn diffusion mechanism is bulk diffusion, and not intergranular. This is a surprise. However, it means that quantification of the Zn diffusivities in these samples will be significantly simpler than would have been the case if grain boundary diffusion dominated. In addition to the laboratory testing, gas impinger and particulate samples are being collected from a combustor firing syngas and natural gas to determine what types of microcontaminants may reach a turbine firing syngas. The syngas is created in one of two different pilot-scale pressurized coal gasifiers. The initial analysis of the impinger solutions was for standard U.S. Environmental Protection Agency (EPA) Method 29 determination of hazardous metals and did not include major element analysis. When syngas is fired, the amount of Mn in the combustor gas increases substantially. Halogens (Br2 and Cl2) and hydrogen

  11. Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites

    NASA Technical Reports Server (NTRS)

    Hoffman, Douglas C.; Potter, Benjamin

    2013-01-01

    Quality knives are typically fabricated from high-strength steel alloys. Depending on the application, there are different requirements for mechanical and physical properties that cause problems for steel alloys. For example, diver's knives are generally used in salt water, which causes rust in steel knives. Titanium diver's knives are a popular alternative due to their salt water corrosion resistance, but are too soft to maintain a sharp cutting edge. Steel knives are also magnetic, which is undesirable for military applications where the knives are used as a tactical tool for diffusing magnetic mines. Steel is also significantly denser than titanium (8 g/cu cm vs. 4.5 g/cu cm), which results in heavier knives for the same size. Steel is hard and wear-resistant, compared with titanium, and can keep a sharp edge during service. A major drawback of both steel and titanium knives is that they must be ground or machined into the final knife shape from a billet. Since most knives have a mirrored surface and a complex shape, manufacturing them is complex. It would be more desirable if the knife could be cast into a net or near-net shape in a single step. The solution to the deficiencies of titanium, steel, and ceramic knives is to fabricate them using bulk metallic glasses (or composites). These alloys can be cast into net or near-net shaped knives with a combination of properties that exceed both titanium and steel. A commercially viable BMG (bulk metallic glass) or composite knife is one that exhibits one or all of the following properties: It is based on titanium, has a self-sharpening edge, can retain an edge during service, is hard, is non-magnetic, is corrosion-resistant against a variety of corrosive environments, is tough (to allow for prying), can be cast into a net-shape with a mirror finish and a complex shape, has excellent wear resistance, and is low-density. These properties can be achieved in BMG and composites through alloy chemistry and processing. For

  12. Boric/sulfuric acid anodizing of aluminum alloys 2024 and 7075: Film growth and corrosion resistance

    SciTech Connect

    Thompson, G.E.; Zhang, L.; Smith, C.J.E.; Skeldon, P.

    1999-11-01

    The influence of boric acid (H{sub 3}BO{sub 3}) additions to sulfuric acid (H{sub 2}SO{sub 4}) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (Na{sub 2}Cr{sub 2}O{sub 7})/H{sub 2}SO{sub 4} (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of H{sub 3}BO{sub 3} to 50 g/L. Pretreatments affected the initial film development prior to the establishment of the steady-state morphology of the porous film, which was related to the different compositions and morphologies of pretreated surfaces. More detailed studies of the Al 7075-T6 alloy indicated negligible effects of H{sub 3}BO{sub 3} on the coating weight, morphology of the anodic film, and thickening rate of the film, or corrosion resistance provided by the film. In salt spray tests, unsealed films formed in H{sub 2}SO{sub 4} or mixed acid yielded similar poor corrosion resistances, which were inferior to that provided by anodizing in chromic acid (H{sub 2}CrO{sub 4}). Sealing of films in deionized water, or preferably in chromate solution, improved corrosion resistance, although not matching the far superior performance provided by H{sub 2}CrO{sub 4} anodizing and sealing.

  13. Taguchi Optimization of Pulsed Current GTA Welding Parameters for Improved Corrosion Resistance of 5083 Aluminum Welds

    NASA Astrophysics Data System (ADS)

    Rastkerdar, E.; Shamanian, M.; Saatchi, A.

    2013-04-01

    In this study, the Taguchi method was used as a design of experiment (DOE) technique to optimize the pulsed current gas tungsten arc welding (GTAW) parameters for improved pitting corrosion resistance of AA5083-H18 aluminum alloy welds. A L9 (34) orthogonal array of the Taguchi design was used, which involves nine experiments for four parameters: peak current ( P), base current ( B), percent pulse-on time ( T), and pulse frequency ( F) with three levels was used. Pitting corrosion resistance in 3.5 wt.% NaCl solution was evaluated by anodic polarization tests at room temperature and calculating the width of the passive region (∆ E pit). Analysis of variance (ANOVA) was performed on the measured data and S/ N (signal to noise) ratios. The "bigger is better" was selected as the quality characteristic (QC). The optimum conditions were found as 170 A, 85 A, 40%, and 6 Hz for P, B, T, and F factors, respectively. The study showed that the percent pulse-on time has the highest influence on the pitting corrosion resistance (50.48%) followed by pulse frequency (28.62%), peak current (11.05%) and base current (9.86%). The range of optimum ∆ E pit at optimum conditions with a confidence level of 90% was predicted to be between 174.81 and 177.74 mVSCE. Under optimum conditions, the confirmation test was carried out, and the experimental value of ∆ E pit of 176 mVSCE was in agreement with the predicted value from the Taguchi model. In this regard, the model can be effectively used to predict the ∆ E pit of pulsed current gas tungsten arc welded joints.

  14. A robust superhydrophobic PVDF composite coating with wear/corrosion-resistance properties

    NASA Astrophysics Data System (ADS)

    Wang, Huaiyuan; Liu, Zhanjian; Wang, Enqun; Yuan, Ruixia; Gao, Dong; Zhang, Xiguang; Zhu, Yanji

    2015-03-01

    A robust wear/corrosion-resistant superhydrophobic polyvinylidene fluoride (PVDF)/fluorinated ethylene propylene (FEP)/carbon nanofibers (CNFs) composite coating with a water contact angle (WCA) of 164 ± 1.5° and a slide angle of 5 ± 0.2° has been fabricated through the combination of chemical etching and spraying technique. The WCA of the coating still maintains 141 ± 1.2° after 10,000 times rubbing due to the designed internal nano/micro-structure and the slide angle increases from 5 ± 0.2° to 20 ± 0.5°. The prepared coating also demonstrates excellent corrosion-resistance property under strongly acidic or alkaline conditions for 15 days. The wear-resistance of the superhydrophobic coating is approximately 5 times higher than the pure PVDF coating and commercial fluorocarbon coating. These excellent mechanical properties are attributed to the new groups of Cdbnd C and Csbnd C by dehydrofluorination of PVDF and the new β-phase of PVDF by recrystallization of the α-phase. Furthermore, the enhanced adhesive ability of the coating corresponds with Grade 1 according to GB/T9286, mainly because that the interaction force among PVDF macromolecules can be intensified by chemical cross-linking and the hydroxyl groups formed on the surface of the aluminum plate by etching. It is believed that this robust multifunctional superhydrophobic coating may have the potential values in large-scale application.

  15. Fracture toughness and corrosion resistance of semisolid AlSi5 alloy

    NASA Astrophysics Data System (ADS)

    Pola, A.; Montesano, L.; Gelfi, M.; Roberti, R.

    2011-05-01

    The aim of this work was to investigate fracture toughness and corrosion resistance of semisolid AlSi5 castings, compared to samples obtained from conventional casting operations. In order to have a semisolid microstructure, the melt alloy was treated by means of ultrasound during solidification and then poured into permanent moulds. Mechanical properties of semisolid and conventional castings were compared by means of ultimate tensile strength (Rm), yield stress (Rp02) and hardness (HV) measurements. Fracture mechanics tests were carried out on Single Edge Notched Bend (SENB) specimens, machined from castings, and pre-cracked by fatigue. These tests were performed to determine the effect of the microstructure on the J-Integral resistance (J-R) behavior and to deeply understand the ductile fracture behaviour of semisolid parts. The J-Integral versus spaced crack extension (J-Δa) curves showed an improved resistance of the semisolid microstructure, due to the higher ductility. Finally, the corrosion behaviour of semisolid samples was compared to that of castings coming from solidification of fully liquid alloy by means of electrochemical potentiodynamic polarization tests. It was observed that the globular microstructure offers better quality, in terms of higher mechanical properties, as a consequence of a more uniform distribution of the solute.

  16. Fracture toughness and corrosion resistance of semisolid AlSi5 alloy

    SciTech Connect

    Pola, A.; Montesano, L.; Gelfi, M.; Roberti, R.

    2011-05-04

    The aim of this work was to investigate fracture toughness and corrosion resistance of semisolid AlSi5 castings, compared to samples obtained from conventional casting operations. In order to have a semisolid microstructure, the melt alloy was treated by means of ultrasound during solidification and then poured into permanent moulds. Mechanical properties of semisolid and conventional castings were compared by means of ultimate tensile strength (R{sub m}), yield stress (Rp{sub 02}) and hardness (HV) measurements. Fracture mechanics tests were carried out on Single Edge Notched Bend (SENB) specimens, machined from castings, and pre-cracked by fatigue. These tests were performed to determine the effect of the microstructure on the J-Integral resistance (J-R) behavior and to deeply understand the ductile fracture behaviour of semisolid parts. The J-Integral versus spaced crack extension (J-{Delta}a) curves showed an improved resistance of the semisolid microstructure, due to the higher ductility. Finally, the corrosion behaviour of semisolid samples was compared to that of castings coming from solidification of fully liquid alloy by means of electrochemical potentiodynamic polarization tests. It was observed that the globular microstructure offers better quality, in terms of higher mechanical properties, as a consequence of a more uniform distribution of the solute.

  17. Influence of fluoride content and pH on the corrosion resistance of titanium and its alloys.

    PubMed

    Schiff, Nicolas; Grosgogeat, Brigitte; Lissac, Michele; Dalard, Francis

    2002-05-01

    In the last decade, new titanium alloys have been developed in different areas of dentistry, such as TiAl6V4 and NiTi. Concurrently, treatments using fluoride supplementation, such as odontology fluoride containing gels, have also been widely used in odontology. The aim of this study was to compare the NiTi, NiTiCo and TiAl6V4 alloys with the titanium, regarding the corrosion resistance in Fusayama Meyer artificial saliva with different pH and fluoride contents. In the experimental methods, the corrosion potential was measured over time, then a linear sweep voltametric analysis measured the polarization resistances and corrosion currents. Our results have shown that TiAl6V4 alloys have a good corrosion resistance as good as that of titanium in Fusayama Meyer saliva and acid salivary solution, except NiTi and NiTiCo alloys. Conversely, we noticed, as for the titanium, a remarkable localized corrosion phenomenon of those new alloys in fluoride and acid-fluoride salivary solutions. The fluoride ions could cause the breakdown of the protective passivation layer that normally exists on the titanium and its alloys, leading to pit corrosion.

  18. Corrosion resistance, chemistry, and mechanical aspects of Nitinol surfaces formed in hydrogen peroxide solutions.

    PubMed

    Shabalovskaya, Svetlana A; Anderegg, James W; Undisz, Andreas; Rettenmayr, Markus; Rondelli, Gianni C

    2012-08-01

    Ti oxides formed naturally on Nitinol surfaces are only a few nanometers thick. To increase their thickness, heat treatments are explored. The resulting surfaces exhibit poor resistance to pitting corrosion. As an alternative approach to accelerate surface oxidation and grow thicker oxides, the exposure of Nitinol to strong oxidizing H(2)O(2) aqueous solutions (3 and 30%) for various periods of time was used. Using X-Ray Photoelectron Spectroscopy (XPS) and Auger spectroscopy, it was found that the surface layers with variable Ti (6-15 at %) and Ni (5-13 at %) contents and the thickness up to 100 nm without Ni-enriched interfaces could be formed. The response of the surface oxides to stress in superelastic regime of deformations depended on oxide thickness. In the corrosion studies performed in both strained and strain-free states using potentiodynamic and potentiostatic polarizations, the surfaces treated in H(2)O(2) showed no pitting in corrosive solution that was assigned to higher chemical homogeneity of the surfaces free of secondary phases and inclusions that assist better biocompatibility of Nitinol medical devices.

  19. Corrosion Resistance and Color Properties of Anodized Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Karambakhsh, Ali; Afshar, Abdollah; Malekinejad, Pejman

    2012-01-01

    In this research, color anodizing of Ti-6Al-4V alloy was performed in phosphoric acid solution of 0.4 M concentration and within 30 s in different voltages (10-120 V) of a DC power supply. The effect of anodizing voltages on the color and thickness of anodized layers on Ti-6Al-4V alloy surface was surveyed. Thickness and refractive index of layers were measured by spectrophotometery and reflectance curves. According to the results, thickness of layers increased with increasing anodizing voltage and was in the range of 38-167 nm. Also the refractive index of anodic film was approximately constant at about 2 and increased inconsiderably with increasing anodizing voltage. Corrosion resistance of the anodized samples in 20 and 50 V was surveyed in physiological solutions of Ringer's solution, Artificial Saliva solution, and Ringer's + 150 mM H2O2 solution at the temperature of 37 °C by potentiodynamic polarization method. The anodized sample in 50 V indicated lower corrosion rate than the non-anodized sample as well as the sample which was anodized in 20 V in all solutions. The non-anodized sample indicated the highest corrosion rate of about 0.25 μA cm-2.

  20. Microbiological influenced corrosion resistance characteristics of a 304L-Cu stainless steel against Escherichia coli.

    PubMed

    Nan, Li; Xu, Dake; Gu, Tingyue; Song, Xiu; Yang, Ke

    2015-03-01

    Cu-bearing antibacterial stainless steels have been gaining popularity in recent years due to their strong antibacterial performances. However, only a few studies were reported for their actual performances against microbiologically influenced corrosion (MIC). In this study, electrochemical methods and surface analytical techniques were applied to study the MIC resistance characteristics of a 304L-Cu stainless steel (SS) against Escherichia coli in comparison with 304L SS as control. Corrosion tests for specimens after a 21-day exposure to a Luria-Bertani (LB) culture medium with E. coli demonstrated that the 304L-Cu SS considerably reduced the maximum MIC pit depth and the specific weight loss compared with 304L SS (8.3μm and 0.2mg/cm(2) vs. 13.4μm and 0.6mg/cm(2)). Potentiodynamic polarization tests showed that the corrosion current density of the 304L-Cu SS was as much as 4 times lower than that of the 304L SS, indicating that the 304L-Cu SS is a better choice for applications in MIC-prone environments.

  1. Microstructures, mechanical properties and corrosion resistances of extruded Mg-Zn-Ca-xCe/La alloys.

    PubMed

    Tong, L B; Zhang, Q X; Jiang, Z H; Zhang, J B; Meng, J; Cheng, L R; Zhang, H J

    2016-09-01

    Magnesium alloys are considered as good candidates for biomedical applications, the influence of Ce/La microalloying on the microstructure, mechanical property and corrosion performance of extruded Mg-5.3Zn-0.6Ca (wt%) alloy has been investigated in the current study. After Ce/La addition, the conventional Ca2Mg6Zn3 phases are gradually replaced by new Mg-Zn-Ce/La-(Ca) phases (T1'), which can effectively divide the Ca2Mg6Zn3 phase. The Ca2Mg6Zn3/T1' structure in Mg-Zn-Ca-0.5Ce/La alloy is favorably broken into small particles during the extrusion, resulting in an obvious refinement of secondary phase. The dynamic recrystallized grain size is dramatically decreased after 0.5Ce/La addition, and the tensile yield strength is improved, while further addition reverses the effect, due to the grain coarsening. However, the corrosion resistance of extruded Mg-Zn-Ca alloy deteriorates after Ce/La addition, because the diameter of secondary phase particle is remarkably decreased, which increases the amount of cathodic sites and accelerates the galvanic corrosion process.

  2. Influence of electropolishing and anodic oxidation on morphology, chemical composition and corrosion resistance of niobium.

    PubMed

    Sowa, Maciej; Greń, Katarzyna; Kukharenko, Andrey I; Korotin, Danila M; Michalska, Joanna; Szyk-Warszyńska, Lilianna; Mosiałek, Michał; Zak, Jerzy; Pamuła, Elżbieta; Kurmaev, Ernst Z; Cholakh, Seif O; Simka, Wojciech

    2014-09-01

    The work presents results of the studies performed on electropolishing of pure niobium in a bath that contained: sulphuric acid, hydrofluoric acid, ethylene glycol and acetanilide. After the electropolishing, the specimens were subjected to anodic passivation in a 1moldm(-3) phosphoric acid solution at various voltages. The surface morphology, thickness, roughness and chemical composition of the resulting oxide layers were analysed. Thusly prepared niobium samples were additionally investigated in terms of their corrosion resistance in Ringer's solution. The electropolished niobium surface was determined to be smooth and lustrous. The anodisation led to the growth of barrier-like oxide layers, which were enriched in phosphorus species.

  3. Robust superhydrophobic surface on Al substrate with durability, corrosion resistance and ice-phobicity

    NASA Astrophysics Data System (ADS)

    Wang, Guoyong; Liu, Shuai; Wei, Sufeng; Liu, Yan; Lian, Jianshe; Jiang, Qing

    2016-02-01

    Practical application of superhydrophobic surfaces is limited by the fragility of nanoscale asperities. Combining chemical etching and anodization, microscale pits and nanoscale pores, instead of the micro and nano protrusions on traditional superhydrophobic surfaces mimicking Lutos leaves, were fabricated on commercially pure aluminum surfaces. After modified by FDTS, the surfaces were superhydrophobic and self-cleaning. The ultrahigh hardness and electrochemical stability of Al2O3 coating endowed the surface excellent mechanical durability and good corrosion resistance. Because the method is scalable, it may find practical application on body panels of automobiles and aircrafts and so on.

  4. Robust superhydrophobic surface on Al substrate with durability, corrosion resistance and ice-phobicity

    PubMed Central

    Wang, Guoyong; Liu, Shuai; Wei, Sufeng; Liu, Yan; Lian, Jianshe; Jiang, Qing

    2016-01-01

    Practical application of superhydrophobic surfaces is limited by the fragility of nanoscale asperities. Combining chemical etching and anodization, microscale pits and nanoscale pores, instead of the micro and nano protrusions on traditional superhydrophobic surfaces mimicking Lutos leaves, were fabricated on commercially pure aluminum surfaces. After modified by FDTS, the surfaces were superhydrophobic and self-cleaning. The ultrahigh hardness and electrochemical stability of Al2O3 coating endowed the surface excellent mechanical durability and good corrosion resistance. Because the method is scalable, it may find practical application on body panels of automobiles and aircrafts and so on. PMID:26853810

  5. Effect of ultrafine grain on tensile behaviour and corrosion resistance of the duplex stainless steel.

    PubMed

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

    2016-05-01

    The ultrafine grained 2205 duplex stainless steel was obtained by cold rolling and annealing. The tensile properties were investigated at room temperature. Comparing with coarse grained stainless steel, ultrafine grained sample showed higher strength and plasticity. In addition, grain size changed deformation orientation. The strain induced α'-martensite was observed in coarse grained 2205 duplex stainless steel with large strain. However, the grain refinement inhibited the transformation of α'-martensite;nevertheless, more deformation twins improved the strength and plasticity of ultrafine grained 2205 duplex stainless steel. In addition, the grain refinement improved corrosion resistance of the 2205 duplex stainless steel in sodium chloride solution.

  6. Amorphous metal formulations and structured coatings for corrosion and wear resistance

    DOEpatents

    Farmer, Joseph C [Tracy, CA

    2011-12-13

    A system for coating a surface comprising providing a source of amorphous metal that contains more than 11 elements and applying the amorphous metal that contains more than 11 elements to the surface by a spray. Also a coating comprising a composite material made of amorphous metal that contains more than 11 elements. An apparatus for producing a corrosion-resistant amorphous-metal coating on a structure comprises a deposition chamber, a deposition source in the deposition chamber that produces a deposition spray, the deposition source containing a composite material made of amorphous metal that contains more than 11 elements, and a system that directs the deposition spray onto the structure.

  7. Amorphous metal formulations and structured coatings for corrosion and wear resistance

    DOEpatents

    Farmer, Joseph C.

    2014-07-15

    A system for coating a surface comprising providing a source of amorphous metal that contains more than 11 elements and applying the amorphous metal that contains more than 11 elements to the surface by a spray. Also a coating comprising a composite material made of amorphous metal that contains more than 11 elements. An apparatus for producing a corrosion-resistant amorphous-metal coating on a structure comprises a deposition chamber, a deposition source in the deposition chamber that produces a deposition spray, the deposition source containing a composite material made of amorphous metal that contains more than 11 elements, and a system that directs the deposition spray onto the structure.

  8. Robust superhydrophobic surface on Al substrate with durability, corrosion resistance and ice-phobicity.

    PubMed

    Wang, Guoyong; Liu, Shuai; Wei, Sufeng; Liu, Yan; Lian, Jianshe; Jiang, Qing

    2016-02-08

    Practical application of superhydrophobic surfaces is limited by the fragility of nanoscale asperities. Combining chemical etching and anodization, microscale pits and nanoscale pores, instead of the micro and nano protrusions on traditional superhydrophobic surfaces mimicking Lutos leaves, were fabricated on commercially pure aluminum surfaces. After modified by FDTS, the surfaces were superhydrophobic and self-cleaning. The ultrahigh hardness and electrochemical stability of Al2O3 coating endowed the surface excellent mechanical durability and good corrosion resistance. Because the method is scalable, it may find practical application on body panels of automobiles and aircrafts and so on.

  9. Development of improved and corrosion-resistant surfaces for fossil power system components

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Goodwin, G.M.

    1996-06-01

    The purpose of this task is to develop the corrosion-resistant surfaces on a variety of fossil power system components. The Fe-Al alloys ranging in aluminum from 16 to 36 @ % are of interest. The surfaces of Fe-Al alloys can be produced by weld overlay. However, because of their limited room-temperature ductility, the production of weld wire for these compositions is not commercially feasible. The alloying element dilution during weld overlay also makes depositing exact surface composition rather difficult.

  10. Corrosion resistance and development length of steel reinforcement with cementitious coatings

    NASA Astrophysics Data System (ADS)

    Pei, Xiaofei

    This research program focused on the corrosion resistance and development length of reinforcing steel coated with Cementitious Capillary Crystalline Waterproofing (CCCW) materials. The first part of this research program involved using the half-cell potential method to evaluate the corrosion resistance of CCCW coating materials. One hundred and two steel bars were embedded in concrete cylinders and monitored. In total, 64 steel reinforcing bars were coated with CCCW prior to embedment, 16 mortar cylinders were externally coated with CCCW, and 22 control (uncoated) samples were tested. All the samples were immersed in a 3.5% concentration chloride solution for a period of one year. Three coating types were studied: CCCW-B, CCCW-B+ C and CCCW-C+D. The test results showed that the CCCW coating materials delayed the corrosion activity to varying degrees. In particular, CCCW-C+D applied on the reinforcing steel surface dramatically delayed the corrosion activity when compared to the control samples. After being exposed to the chloride solution for a period of one year, no sign of corrosion was observed for the cylinders where the concrete surface was coated. The second part of this research evaluated the bond strength and development length of reinforcing steel coated with two types of CCCW coating materials (CCCW-B+C and CCCW-C+D) using a modified pull-out test method. A self-reacting inverted T-shaped beam was designed to avoid compression in the concrete surrounding the reinforcing steel. Steel reinforcing bars were embedded along the web portion of the T-beam with various embedded lengths and were staggered side by side. In total, six T-beams were fabricated and each beam contained 8 samples. Both short-term (7 days) and long-term (3 months) effects of water curing were evaluated. The reinforcing steel bars coated with CCCW-B+C demonstrated a higher bond strength than did samples coated with CCCW-C+D. However, the bond strengths of samples with coating materials

  11. Halogen-Containing Gases as Boundary Lubricants for Corrosion-Resistant Alloys at 1200 F

    NASA Technical Reports Server (NTRS)

    Buckley, Donald H.; Johnson, Robert L.

    1959-01-01

    The extreme temperatures anticipated for lubricated parts in advanced flight powerplants dictate the consideration of unconventional methods of lubrication such as solid lubricants and the reactive gases described in the present research. These halogen-containing "reactive" gases such as dichlorodifluoromethane, CF2Cl2, are among the most stable of organic molecules. The high "flash" temperatures generated at the contacting asperities as a result of frictional heat are sufficient to cause local decomposition of the halogen-containing gases. The active atoms thus released (e.g., chlorine) then react with the metal to be lubricated to form halides capable of effective lubrication. The presence of small amounts of a sulfur-containing gas (e.g., 1 percent sulfur hexafluoride, SF6) was found to catalyze the formation of metal halides. Friction and wear studies were made with a hemisphere (3/16-in. rad.) rider sliding in a circumferential path on the flat surface of a rotating disk (2 1/2-in. diam.). The specimens of corrosion-resistant 2 alloys were run in an atmosphere of the various gases with a load of 1200 grams, a sliding velocity of 120 feet per minute, and temperature from 75 to 1200 F. An effective lubricant for ferritic materials (M-1 tool steel) was CF2Cl2, but significant corrosion occurred above 600 F. Corrosion evaluation in CF2Cl2 suggested a number of nickel- and cobalt-base alloys for additional lubrication study. Several combinations of gases and these metals were found to lubricate to 1200 F without excessive corrosion. The gases were CF2Cl2 Plus 1 percent SF6, monobromotrifluoromethane CF3Br plus 1 percent SF6, dibromodifluoromethane CF2Br2, iodotrifluoromethane, CF3I, and I2. Careful selection of metals and gas are necessary for successful lubrication over specific temperature ranges. Optimum combinations give friction coefficients as low as 0.05 without

  12. Effects of Peracetic Acid on the Corrosion Resistance of Commercially Pure Titanium (grade 4).

    PubMed

    Raimundo, Lariça B; Orsi, Iara A; Kuri, Sebastião E; Rovere, Carlos Alberto D; Busquim, Thaís P; Borie, Eduardo

    2015-01-01

    The aim of this study was to evaluate the corrosion resistance of pure titanium grade 4 (cp-Ti-4), subjected to disinfection with 0.2% and 2% peracetic acid during different immersion periods using anodic potentiodynamic polarization test in acid and neutral artificial saliva. Cylindrical samples of cp-Ti-4 (5 mm x 5 mm) were used to fabricate 24 working electrodes, which were mechanically polished and divided into eight groups (n=3) for disinfection in 2% and 0.2% peracetic acid for 30 and 120 min. After disinfection, anodic polarization was performed in artificial saliva with pH 4.8 and 6.8 to assess the electrochemical behavior of the electrodes. A conventional electrochemical cell, constituting a reference electrode, a platinum counter electrode, and the working electrode (cp-Ti specimens) were used with a scanning rate of 1 mV/s. Three curves were obtained for each working electrode, and corrosion was characterized by using scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS). Data of corrosion potential (Ecorr) and passive current (Ipass) obtained by the polarization curves were analyzed statistically by Student's t-test (a=0.05). The statistical analysis showed no significant differences (p>0.05) between artificial saliva types at different concentrations and periods of disinfection, as well as between control and experimental groups. No surface changes were observed in all groups evaluated. In conclusion, disinfection with 0.2% and 2% peracetic acid concentrations did not cause corrosion in samples manufactured with cp-Ti-4.

  13. The Effect of Coating Thickness on Corrosion Resistance of Hydroxyapatite Coated Ti6Al4V and 316L SS Implants

    NASA Astrophysics Data System (ADS)

    Aksakal, B.; Gavgali, M.; Dikici, B.

    2010-08-01

    Hydroxyapatite (HAP) has been coated onto Ti6Al4V and 316L SS substrates by sol-gel method. The coating thicknesses for the analysis were about 40 and 72 μm. Adhesion and corrosion tests have been conducted on uncoated and HAP-coated substrates. The coatings were characterized by XRD, SEM, and adhesion analysis. The corrosion resistance was examined in vitro by potentiodynamic polarization technique in Ringer’s solution at room temperature. Electrochemical analysis indicated that the highest corrosion susceptibility was found on 72-μm-coated 316L SS, and the 40-μm HAP-coated Ti6Al4V showed the highest corrosion resistance. It was observed that the coating thickness was an effective parameter on both adhesion and corrosion resistance. It was shown that adhesion and corrosion resistance decreased with increasing coating thickness on both substrates.

  14. Corrosion resistance of flaky aluminum pigment coated with cerium oxides/hydroxides in chloride and acidic electrolytes

    NASA Astrophysics Data System (ADS)

    Niroumandrad, S.; Rostami, M.; Ramezanzadeh, B.

    2015-12-01

    The objective of this study was to enhance the corrosion resistance of lamellar aluminum pigment through surface treatment by cerium oxides/hydroxides. The surface composition of the pigments was studied by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the pigment was evaluated by conventional hydrogen evolution measurements in acidic solution and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. Results showed that the Ce-rich coating composed of Ce2O3 and CeO2 was precipitated on the pigment surface after immersion in the cerium solution. The corrosion resistance of pigment was significantly enhanced after modification with cerium layer.

  15. Microstructure Characterization and Corrosion Resistance Behavior of New Cobalt-Free Maraging Steel Produced Through ESR Techniques

    NASA Astrophysics Data System (ADS)

    Seikh, Asiful H.; Halfa, Hossam; Baig, Muneer; Khan, Sohail M. A.

    2017-03-01

    In this study, two different grades (M23 and M29) of cobalt-free low nickel maraging steel have been produced through electroslag remelting (ESR) process. The corrosion resistance of these ESR steels was investigated in 1 M H2SO4 solution using linear potentiodynamic polarization (LPP) and electrochemical impedance spectroscopy (EIS) techniques. The experiments were performed for different immersion time and solution temperature. To evaluate the corrosion resistance of the ESR steels, some significant characterization parameters from LPP and EIS curves were analyzed and compared with that of conventional C250 maraging steel. Irrespective of measurement techniques used, the results show that the corrosion resistance of the ESR steels was higher than the C250 steel. The microstructure of ESR steels was composed of uniform and well-distributed martensite accompanied with little amount of retained austenite in comparison with C250 steel.

  16. Corrosion resistance, surface mechanical properties, and cytocompatibility of plasma immersion ion implantation-treated nickel-titanium shape memory alloys.

    PubMed

    Yeung, K W K; Poon, R W Y; Liu, X Y; Ho, J P Y; Chung, C Y; Chu, P K; Lu, W W; Chan, D; Cheung, K M C

    2005-11-01

    Nickel-titanium shape memory alloys are promising materials in orthopedic applications because of their unique properties. However, for prolonged use in a human body, deterioration of the corrosion resistance of the materials becomes a critical issue because of the increasing possibility of deleterious ions released from the substrate to living tissues. We have investigated the use of nitrogen, acetylene, and oxygen plasma immersion ion implantation (PIII) to improve the corrosion resistance and mechanical properties of the materials. Our results reveal that the corrosion resistance and mechanical properties such as hardness and elastic modulus are significantly enhanced after surface treatment. The release of nickel is drastically reduced as compared with the untreated control. In addition, our in vitro tests show that the plasma-treated surfaces are well tolerated by osteoblasts. Among the three types of samples, the best biological effects are observed on the nitrogen PIII samples.

  17. Moessbauer spectroscopy study on the corrosion resistance of plasma nitrided ASTM F138 stainless steel in chloride solution

    SciTech Connect

    Souza, S.D. de; Olzon-Dionysio, M.; Basso, R.L.O.; Souza, S. de

    2010-10-15

    Plasma nitriding of ASTM F138 stainless steel samples has been carried out using dc glow discharge under 80% H{sub 2}-20% N{sub 2} gas mixture, at 673 K, and 2, 4, and 7 h time intervals, in order to investigate the influence of treatment time on the microstructure and the corrosion resistance properties. The samples were characterized by scanning electron microscopy, glancing angle X-ray diffraction and conversion electron Moessbauer spectroscopy, besides electrochemical tests in NaCl aerated solution. A modified layer of about 6 {mu}m was observed for all the nitrided samples, independent of nitriding time. The X-ray diffraction analysis shows broad {gamma}{sub N} phase peaks, signifying a great degree of nitrogen supersaturation. Besides {gamma}{sub N,} the Moessbauer spectroscopy results indicated the occurrence of {gamma}' and {epsilon} phases, as well as some other less important phases. Corrosion measurements demonstrate that the plasma nitriding time affects the corrosion resistance and the best performance is reached at 4 h treatment. It seems that the {epsilon}/{gamma}' fraction ratio plays an important role on the resistance corrosion. Additionally, the Moessbauer spectroscopy was decisive in this study, since it was able to identify and quantify the iron phases that influence the corrosion resistance of plasma nitrided ASTM F138 samples.

  18. Ion beam analysis, corrosion resistance and nanomechanical properties of TiAlCN/CNx multilayer grown by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Alemón, B.; Flores, M.; Canto, C.; Andrade, E.; de Lucio, O. G.; Rocha, M. F.; Broitman, E.

    2014-07-01

    A novel TiAlCN/CNx multilayer coating, consisting of nine TiAlCN/CNx periods with a top layer 0.5 μm of CNx, was designed to enhance the corrosion resistance of CoCrMo biomedical alloy. The multilayers were deposited by dc and RF reactive magnetron sputtering from Ti0.5Al0.5 and C targets respectively in a N2/Ar plasma. The corrosion resistance and mechanical properties of the multilayer coatings were analyzed and compared to CoCrMo bulk alloy. Ion beam analysis (IBA) and X-ray diffraction tests were used to measure the element composition profiles and crystalline structure of the films. Corrosion resistance was evaluated by means of potentiodynamic polarization measurements using simulated body fluid (SBF) at typical body temperature and the nanomechanical properties of the multilayer evaluated by nanoindentation tests were analyzed and compared to CoCrMo bulk alloy. It was found that the multilayer hardness and the elastic recovery are higher than the substrate of CoCrMo. Furthermore the coated substrate shows a better general corrosion resistance than that of the CoCrMo alloy alone with no observation of pitting corrosion.

  19. New chemical treatment for bioactive titanium alloy with high corrosion resistance.

    PubMed

    Spriano, S; Bronzoni, M; Rosalbino, F; Vernè, E

    2005-03-01

    It was recently claimed that titanium metal and its alloys can bond to the living bone, without being coated by apatite (VPS coatings), but by being chemically and heat-treated. The bioactivity of treated titanium is of interest because of the opportunity to obtain orthopaedic or dental implants presenting, at the same time, high toughness, strength and fatigue resistance as well as bone-bonding ability. The bioactive behaviour of the treated implants is due to the presence of a modified surface, which, during soaking in body fluid, promotes the precipitation of apatite. The apatite formed is strongly bonded to the substrate and promotes living bone bonding. In this work were characterised samples of Ti-6Al-7Nb alloy with surfaces presenting a different chemical and mechanical state. The aim of the research was twofold. The first objective was to characterise chemically and heat-treated samples with different surface topography, in order to define the best conditions for osteogenic integration. The second aim was to assess the corrosion behaviour of the bioactive implants, because they expose a microporous and quite thin modified surface layer. No-treated and passivated samples, with a surface state closed to that nowadays used on implants, were used as reference. The surface structure, morphology, electrochemical behaviour and bioactivity of the different samples were assessed by means of XRD, SEM-EDS, anodic polarizations, open circuit measurements and in-vitro tests. Results evidence that it is possible to modify the surface of the Ti-6Al-7Nb alloy in order to obtain the formation of a bioactive layer and that the substrate roughness influences the characteristics of the surface layer formed. It was also evidenced that the as treated surfaces present inadequate corrosion behaviour, so a new two-step chemical treatment has been developed in order to obtain a bioactive material with good corrosion resistance.

  20. Enhanced osteoblast proliferation and corrosion resistance of commercially pure titanium through surface nanostructuring by ultrasonic shot peening and stress relieving.

    PubMed

    Jindal, Shitu; Bansal, Rajesh; Singh, Bijay P; Pandey, Rajiv; Narayanan, Shankar; Wani, Mohan R; Singh, Vakil

    2014-07-01

    This investigation was carried out to study the effect of a novel process of surface modification, surface nanostructuring by ultrasonic shot peening, on osteoblast proliferation and corrosion behavior of commercially pure titanium (c p-Ti) in simulated body fluid. A mechanically polished disc of c p-Ti was subjected to ultrasonic shot peening with stainless steel balls to create nanostructure at the surface. A nanostructure (<20 nm) with inhomogeneous distribution was revealed by atomic force and scanning electron microscopy. There was an increase of approximately 10% in cell proliferation, but there was drastic fall in corrosion resistance. Corrosion rate was increased by 327% in the shot peened condition. In order to examine the role of residual stresses associated with the shot peened surface on these aspects, a part of the shot peened specimen was annealed at 400°C for 1 hour. A marked influence of annealing treatment was observed on surface structure, cell proliferation, and corrosion resistance. Surface nanostructure was much more prominent, with increased number density and sharper grain boundaries; cell proliferation was enhanced to approximately 50% and corrosion rate was reduced by 86.2% and 41% as compared with that of the shot peened and the as received conditions, respectively. The highly significant improvement in cell proliferation, resulting from annealing of the shot peened specimen, was attributed to increased volume fraction of stabilized nanostructure, stress recovery, and crystallization of the oxide film. Increase in corrosion resistance from annealing of shot peened material was related to more effective passivation. Thus, the surface of c p-Ti, modified by this novel process, possessed a unique quality of enhancing cell proliferation as well as the corrosion resistance and could be highly effective in reducing treatment time of patients adopting dental and orthopedic implants of titanium and its alloys.

  1. Conducting polymer-coated corrosion resistant metallic bipolar plates for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Joseph, Shine

    2005-11-01

    Concerns over depleting stocks of natural resources and a growing awareness of the environmental damage caused by widespread burning of fossil fuels, and more energy demands brought the idea of alternative energy systems. Proton Exchange Membrane (PEM) fuel cells are one of the fast growing alternative energy technologies. PEM fuel cells generate electricity from an electrochemical reaction between hydrogen and oxygen and produce electricity, a small amount of heat and water and therefore, they are environmentally friendly. Fuel cells are more efficient than internal combustion engines and operate continuously as long as fuel is supplied from an external tank. Fuel cells in stacks are used for most applications because the current output of a PEM fuel cell is around 0.3--0.5 A/cm2. In fuel cell stacks, bipolar plates combine two cells in series with anode and cathode of adjacent cells. The main functions of bipolar plates are electron and gas transport. Bipolar plates are major components in weight and volume of the PEM fuel cell stack and are a significant contributor to the stack cost. The bipolar plate is therefore a key component if power density is to increase and cost to come down. Bipolar plate material should be corrosion resistant, conductive, gas impermeable, light weight (mobile applications) and economical. Graphite plates are used for bipolar plate applications but they are expensive, are brittle to make in thin plates with gas channels on sides, have high manufacturing cost and are gas permeable if too thin. Metals are preferable for bipolar plate application because of better mechanical properties, higher electrical conductivity, lower gas permeability and low cost. In this work Al 6061 and 304 stainless steel alloys are the materials selected for bipolar plates. These metals form non-conductive surface oxides in a PEM fuel cell environment and cause a high contact resistance. This internal resistance lowers the efficiency of PEM fuel cell system. In

  2. Invar and Elinvar type amorphous Fe-Cr-B alloys with high corrosion resistance

    NASA Technical Reports Server (NTRS)

    Kikuci, M.; Fukamichi, K.; Masumoto, T.

    1987-01-01

    Amorphous (Fe(1-x)Cr(x))85B15 alloys (x = 0 to 0.15) were prepared from the melts by rapid quenching using a single roller techinque, and their Invar and Elinvar characteristics and corrosion resistance were investigated. With an increase in chromium content the Curie temperature and the saturation magnetic moment per iron atom decreased monotonically, while the crystallization temperature incresed gradually. The thermal expansion coefficient alpha around room temperature became slightly larger with increasing chromium content. Nevertheless, these amorphous alloys exhibited excellent Invar characteristics below the Curie temperature. The value of Young's modulus increased remarkably in a relatively low magnetic field and then saturated at a field of about 80 kA/m, showing a large delta E effect. Its value as well as a longitudinal linear magnetostriction became smaller with an increase in chromium content. The temperature coefficient of Young's modulus changed from postive to negative, and the temperature range showing the Elinvar characteristics became narrower with chromium content. The temperature coefficient of delay time determined from the values of alpha and e was very small. The corrosion resistance of these alloys was extremely improved by chromium addition.

  3. Preparation, antibacterial effects and corrosion resistant of porous Cu-TiO2 coatings

    NASA Astrophysics Data System (ADS)

    Wu, Haibo; Zhang, Xiangyu; Geng, Zhenhua; Yin, Yan; Hang, Ruiqiang; Huang, Xiaobo; Yao, Xiaohong; Tang, Bin

    2014-07-01

    Antibacterial TiO2 coatings with different concentrations of Cu (Cu-TiO2) were prepared by micro-arc oxidation (MAO) on pre-sputtered CuTi films. The effect of Cu concentrations in CuTi films on the MAO process was investigated. The Cu-TiO2 coatings were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Cu-TiO2 coatings was evaluated via potentiodynamic polarization method. The antibacterial properties were assessed by two methods: spread plate method and fluorescence staining. The experimental results demonstrate that the coatings are porous and consist of anatase phase, rutile phase and unoxidized titanium. The CuTi films are almost completely oxidized and the thickness of all MAO coatings is about 5-10 μm. Cu mainly exists as CuO in the TiO2 coatings. The Cu-TiO2 coatings exhibit excellent antibacterial activities, and the antibacterial rate gradually rise with the increase in Cu concentration in the MAO coatings. The corrosion resistance of MAO coatings is also improved slightly.

  4. Nanocomposite coatings on biomedical grade stainless steel for improved corrosion resistance and biocompatibility.

    PubMed

    Nagarajan, Srinivasan; Mohana, Marimuthu; Sudhagar, Pitchaimuthu; Raman, Vedarajan; Nishimura, Toshiyasu; Kim, Sanghyo; Kang, Yong Soo; Rajendran, Nallaiyan

    2012-10-24

    The 316 L stainless steel is one of the most commonly available commercial implant materials with a few limitations in its ease of biocompatibility and long-standing performance. Hence, porous TiO(2)/ZrO(2) nanocomposite coated over 316 L stainless steels was studied for their enhanced performance in terms of its biocompatibility and corrosion resistance, following a sol-gel process via dip-coating technique. The surface composition and porosity texture was studied to be uniform on the substrate. Biocompatibility studies on the TiO(2)/ZrO(2) nanocomposite coatings were investigated by placing the coated substrate in a simulated body fluid (SBF). The immersion procedure resulted in the complete coverage of the TiO(2)/ZrO(2) nanocomposite (coated on the surface of 316 L stainless steel) with the growth of a one-dimensional (1D) rod-like carbonate-containing apatite. The TiO(2)/ZrO(2) nanocomposite coated specimens showed a higher corrosion resistance in the SBF solution with an enhanced biocompatibility, surpassing the performance of the pure oxide coatings. The cell viability of TiO(2)/ZrO(2) nanocomposite coated implant surface was examined under human dermal fibroblasts culture, and it was observed that the composite coating enhances the proliferation through effective cellular attachment compared to pristine 316 L SS surface.

  5. Electrochemical stability and corrosion resistance of Ti-Mo alloys for biomedical applications.

    PubMed

    Oliveira, N T C; Guastaldi, A C

    2009-01-01

    Electrochemical behavior of pure Ti and Ti-Mo alloys (6-20wt.% Mo) was investigated as a function of immersion time in electrolyte simulating physiological media. Open-circuit potential values indicated that all Ti-Mo alloys studied and pure Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the chloride-containing solution. It also indicated that the addition of Mo to pure Ti up to 15wt.% seems to improve the protection characteristics of its spontaneous oxides. Electrochemical impedance spectroscopy (EIS) studies showed high impedance values for all samples, increasing with immersion time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film present on the metals' surface, improving their resistance with immersion time, presenting the highest values to Ti-15Mo alloy. Potentiodynamic polarization showed a typical valve-metal behavior, with anodic formation of barrier-type oxide films, without pitting corrosion, even in chloride-containing solution. In all cases, the passive current values were quite small, and decrease after 360h of immersion. All these electrochemical results suggest that the Ti-15Mo alloy is a promising material for orthopedic devices, since electrochemical stability is directly associated with biocompatibility and is a necessary condition for applying a material as biomaterial.

  6. Cellulose acetate/hydroxyapatite/chitosan coatings for improved corrosion resistance and bioactivity.

    PubMed

    Zhong, Zhenyu; Qin, Jinli; Ma, Jun

    2015-04-01

    Cellulose acetate (CA) nanofibers were deposited on stainless steel plates by electrospinning technique. The composite of hydroxyapatite (HAP) nanoparticles and chitosan (CHI) was coated subsequently by dip-coating. The structure and morphology of the obtained coatings were investigated by Fourier transform infrared spectroscopy and scanning electron microscopy. The stability of the coatings in physiological environment was studied using electrochemical polarization and impedance spectroscopy. The CA nanofibers were embedded in the HAP/CHI coating and the resulted composite film was densely packed and uniform on the substrate. The in vitro biomineralization study of the coated samples immersed in simulated body fluid (SBF) confirmed the formation ability of bone-like apatite layer on the surface of HAP-containing coatings. Furthermore, the coatings could provide corrosion resistance to the stainless steel substrate in SBF. The electrochemical results suggested that the incorporation of CA nanofibers could improve the corrosion resistance of the HAP/CHI coating. Thus, biocompatible CA/HAP/CHI coated metallic implants could be very useful in the long-term stability of the biomedical applications.

  7. In vitro biocompatibility and corrosion resistance of a new implant titanium base alloy.

    PubMed

    Vasilescu, E; Drob, P; Raducanu, D; Cojocaru, V D; Cinca, I; Iordachescu, D; Ion, R; Popa, M; Vasilescu, C

    2010-06-01

    One objective of this work was to study the corrosion resistance of the new implant Ti-10Zr-5Ta-5Nb alloy in physiological fluids of different pH values, simulating the extreme functional conditions. Another objective was in vitro biocompatibility evaluation of the new alloy using human fetal osteoblast cell line hFOB 1.19. Cytocompatibility was assessed by determination of possible material cytotoxic effects, cell morphology and cell adhesion. The thermo-mechanical processing of the new implant alloy consisted in plastic deformation (almost 90%) performed by hot rolling accompanied by an initial and final heat treatment. The new Ti-10Zr-5Ta-5Nb alloy presented self-passivation, with a large passive potential range and low passive current densities, namely, a very good anticorrosive resistance in Ringer solution of acid, neutral and alkaline pH values. Cell viability was not affected by the alloy substrate presence and a very good compatibility was noticed.

  8. Review on Improving Wear and Corrosion Resistance of Steels via Plasma Electrolytic Saturation Technology

    NASA Astrophysics Data System (ADS)

    Lin, Naiming; Xie, Ruizhen; Zhou, Peng; Zou, Jiaojuan; Ma, Yong; Wang, Zhenxia; Han, Pengju; Wang, Zhihua; Tang, Bin; Tian, Wei

    2016-03-01

    Plasma electrolytic saturation (PES) technique which holds the advantages of short treating time and limited heating influence and immediate quenching effect is conducted under high voltage power supply in some electrolyte has been extensively applied to enhance the surface performance of metallic materials. Steel is widely used in various fields thanks to its promising merits of easy workability, plasticity, toughness and weldability. It accounts for a large proportion in the application scope of the metal materials. Steel surfaces with good corrosion resistance, promising wear resistance and high hardness would be obtained by PES. Meanwhile, uniformed coatings can be formed without special requirements for substrate geometries using the PES. This paper first presents a brief introduction of the technological principle of PES. The status on studies and applications of PES for improving surface performance of steels has been reviewed.

  9. High-temperature corrosion-resistant iron-aluminide (FeAl) alloys exhibiting improved weldability

    DOEpatents

    Maziasz, Philip J.; Goodwin, Gene M.; Liu, Chain T.

    1996-01-01

    This invention relates to improved corrosion-resistant iron-aluminide intermetallic alloys. The alloys of this invention comprise, in atomic percent, from about 30% to about 40% aluminum alloyed with from about 0.1% to about 0.5% carbon, no more than about 0.04% boron such that the atomic weight ratio of boron to carbon in the alloy is in the range of from about 0.01:1 to about 0.08:1, from about 0.01 to about 3.5% of one or more transition metals selected from Group IVB, VB, and VIB elements and the balance iron wherein the alloy exhibits improved resistance to hot cracking during welding.

  10. High-temperature corrosion-resistant iron-aluminide (FeAl) alloys exhibiting improved weldability

    DOEpatents

    Maziasz, P.J.; Goodwin, G.M.; Liu, C.T.

    1996-08-13

    This invention relates to improved corrosion-resistant iron-aluminide intermetallic alloys. The alloys of this invention comprise, in atomic percent, from about 30% to about 40% aluminum alloyed with from about 0.1% to about 0.5% carbon, no more than about 0.04% boron such that the atomic weight ratio of boron to carbon in the alloy is in the range of from about 0.01:1 to about 0.08:1, from about 0.01 to about 3.5% of one or more transition metals selected from Group IVB, VB, and VIB elements and the balance iron wherein the alloy exhibits improved resistance to hot cracking during welding. 13 figs.

  11. Testing and prediction of erosion-corrosion for corrosion resistant alloys used in the oil and gas production industry

    NASA Astrophysics Data System (ADS)

    Rincon, Hernan E.

    The corrosion behavior of CRAs has been thoroughly investigated and documented in the public literature by many researchers; however, little work has been done to investigate erosion-corrosion of such alloys. When sand particles are entrained in the flow, the degradation mechanism is different from that observed for sand-free corrosive environment. There is a need in the oil and gas industry to define safe service limits for utilization of such materials. The effects of flow conditions, sand rate, pH and temperature on the erosion-corrosion of CRAs were widely studied. An extensive experimental work was conducted using scratch tests and flow loop tests using several experimental techniques. At high erosivity conditions, a synergistic effect between erosion and corrosion was observed. Under the high sand rate conditions tested, erosivity is severe enough to damage the passive layer protecting the CRA thereby enhancing the corrosion rate. In most cases there is likely a competition between the rates of protective film removal due to mechanical erosion and protective film healing. Synergism occurs for each of the three alloys examined (13Cr and Super13Cr and 22Cr); however, the degree of synergism is quite different for the three alloys and may not be significant for 22Cr for field conditions where erosivities are typically much lower that those occurring in the small bore loop used in this research. Predictions of the corrosion component of erosion-corrosion based on scratch test data compared reasonably well to test results from flow loops for the three CRAs at high erosivity conditions. Second order behavior appears to be an appropriate and useful model for representing the repassivation process of CRAs. A framework for a procedure to predict penetration rates for erosion-corrosion conditions was developed based on the second order model behavior observed for the re-healing process of the passive film of CRAs and on computational fluid dynamics (CFD) simulations

  12. Effects of sealing treatment on corrosion resistance and degradation behavior of micro-arc oxidized magnesium alloy wires

    NASA Astrophysics Data System (ADS)

    Chu, C. L.; Han, X.; Xue, F.; Bai, J.; Chu, P. K.

    2013-04-01

    The effects of three different sealing treatments on micro-arc oxidized (MAO) medical magnesium alloy wires using boiling water, zirconia sol-gel, and organic gelatin-hydroxyapatite (HA) coatings on the surface morphology, corrosion resistance, and degradation behavior in simulated body fluid (SBF) and simulated intestinal fluid (SIF) are investigated. The treatments involving boiling water or gelatin-HA coating can effectively seal the discharge channels making the surface pores less and smaller. The treatments also improve the corrosion resistance of the MAO magnesium alloy wires, especially the samples with the gelatin-HA coatings which also exhibit reduced degradation in both simulated physiological environments.

  13. Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo.

    PubMed

    Zhao, Bingjing; Wang, Hong; Qiao, Ning; Wang, Chao; Hu, Min

    2017-01-01

    The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (<1.5V) and EBM specimen was the best under the high electric potential (>1.5V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo.

  14. The Influence of Modes of Deposition of Coatings on the Corrosion Resistance of Welded Joints of Steels in Acidic Media;

    NASA Astrophysics Data System (ADS)

    Saraev, Yu N.; Bezborodov, V. P.; Selivanov, Y. V.

    2016-08-01

    In this work, effect of welding on corrosion of welded joints of austenitic steel 12KH18N10T. It is shown that the use of pulsed - arc welding steel 12KH18N10T allows you to create a protective coating with dispersed structure with less thermal impact on the zone of the welded joint. Coating is of such structure allows 1.5 to 6 times to reduce the corrosion rate of welded joints of steel 12KH18N10T in active chemical environments. Pulse the process of deposition of coatings on welded joint of steels can be effectively used for the protection against corrosion in the repair of equipment of chemical industry. The results obtained can be recommended for use when welding a protective corrosion - resistant coatings on working surfaces of equipment of chemical productions.

  15. Effect of exposure time on corrosion resistance of prepassivated UNS S31603 SS in the Gulf of Mexico

    SciTech Connect

    Acuiia, N.; Herniindet-Duque, G.

    1998-12-31

    The effect of exposure time, in the Gulf of Mexico, on the UNS S3 1603 stainless steel (SS) pitting corrosion resistance (PCR), was studied for 30 days using both open circuit potential (OCP) and potentiodynamic polarization (PP) techniques. Biofilm formation and corrosion attack were subsequently observed using scanning electron microscope (SEM) and atomic force microscopy (AFM). It was found that microorganisms colonizing the steel specimen`s surface during the first three days of testing, modified the OCP towards electropositive values, increasing the risk of pitting corrosion. It was also observed, that the SS specimens were most sensitive to pitting corrosion within the first fifteen days of exposure in seawater, decreasing this sensitivity during the last week, probably due to a decay in the biological activity and better behavior of the passive film.

  16. Improvement of abrasion resistance in artificial seawater and corrosion resistance in NaCl solution of 7075 aluminum alloy processed by laser shock peening

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Ning, Chengyi; Huang, Yihui; Cao, Zhenya; Chen, Xiaoxiao; Zhang, Wenwu

    2017-03-01

    As 7075 aluminum alloy is widely used in a humid environment, in order to enhance its abrasion resistance and electrochemical corrosion resistance, the paper studied the effect of laser shock peening on abrasion resistance in artificial seawater and corrosion resistance in 3.5% NaCl solution of 7075 aluminum alloy. Result shows that when specimens were treated once and twice with 7.17 GW/cm2 the abrasion loss would be reduced by 43.75% and 46.09% compare to untreated respectively, and the corrosion rate of 7075 aluminum alloy could be reduced as much as 50.32% by LSP treatment with 7.17 GW/cm2. What's more, the effects on the microhardness, microstructure and residual stress with different LSP impacts and power density were investigated to find out strengthening mechanism of laser shock peening, which were observed and measured by microhardness tester, optical microscope and X-ray diffraction (XRD) residual stress tester. In the entire laboratory tests, it is considered that LSP is a practical option to improve abrasion resistance in seawater and corrosion resistance of 7075 aluminum alloy.

  17. An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water.

    PubMed

    Lee, Han-Seung; Singh, Jitendra Kumar; Ismail, Mohamed A

    2017-02-03

    A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance.

  18. A nanocrystalline zirconium carbide coating as a functional corrosion-resistant barrier for polymer electrolyte membrane fuel cell application

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Li, ZhengYang; Xu, Song; Munroe, Paul; Xie, Zong-Han

    2015-11-01

    A ZrC nanocrystalline coating is engineered onto a Ti-6Al-4V substrate using a double cathode glow discharge technique in order to improve the corrosion resistance and long-term stability of this alloy. The new coating exhibits an extremely dense, homogeneous microstructure composed of equiaxed grains with an average grain size of ∼12 nm and is well adhered on the surface of the substrate. The corrosion behaviour of the coating is systematically investigated using various electrochemical methods, including potentiodynamic, potentiostatic polarizations and electrochemical impedance spectroscopy (EIS), in a simulated polymer electrolyte membrane fuel cell (PEMFC) operating circumstances under different temperatures. The results show that with rising temperature, the corrosion potential (Ecorr) decreases and the corrosion current density (icorr) of the ZrC coated specimen increases, indicating that the corrosion resistance decreased with increasing temperature. However, at a given temperature, the ZrC-coated Ti-6Al-4V alloy has a higher Ecorr and lower icorr as compared to the bare substrate. The results of EIS measurements show that the values of the resistance for the ZrC coated Ti-6Al-4V alloy are three orders of magnitude larger than those of Ti-6A1-4V in the simulated PEMFC environment.

  19. Improved stress corrosion cracking resistance of a novel biodegradable EW62 magnesium alloy by rapid solidification, in simulated electrolytes.

    PubMed

    Hakimi, O; Aghion, E; Goldman, J

    2015-06-01

    The high corrosion rate of magnesium (Mg) and Mg-alloys precludes their widespread acceptance as implantable biomaterials. Here, we investigated the potential for rapid solidification (RS) to increase the stress corrosion cracking (SCC) resistance of a novel Mg alloy, Mg-6%Nd-2%Y-0.5%Zr (EW62), in comparison to its conventionally cast (CC) counterpart. RS ribbons were extrusion consolidated in order to generate bioimplant-relevant geometries for testing and practical use. Microstructural characteristics were examined by SEM. Corrosion rates were calculated based upon hydrogen evolution during immersion testing. The surface layer of the tested alloys was analyzed by X-ray photoelectron spectroscopy (XPS). Stress corrosion resistance was assessed by slow strain rate testing and fractography. The results indicate that the corrosion resistance of the RS alloy is significantly improved relative to the CC alloy due to a supersaturated Nd enrichment that increases the Nd2O3 content in the external oxide layer, as well as a more homogeneous structure and reduced grain size. These improvements contributed to the reduced formation of hydrogen gas and hydrogen embrittlement, which reduced the SCC sensitivity relative to the CC alloy. Therefore, EW62 in the form of a rapidly solidified extruded structure may serve as a biodegradable implant for biomedical applications.

  20. An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water

    PubMed Central

    Lee, Han-Seung; Singh, Jitendra Kumar; Ismail, Mohamed A.

    2017-01-01

    A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance. PMID:28157233

  1. Influence of the post-weld surface treatment on the corrosion resistance of the duplex stainless steel 1.4062

    NASA Astrophysics Data System (ADS)

    Rosemann, P.; Müller, C.; Baumann, O.; Modersohn, W.; Halle, T.

    2017-03-01

    The duplex stainless steel 1.4062 (X2CrNiN22-2) is used as alternative material to austenitic stainless steels in the construction industry. The corrosion resistance of welded seams is influenced by the base material, the weld filler material, the welding process and also by the final surface treatment. The scale layer next to the weld seam can be removed by grinding, pickling, electro-polished or blasting depending on the application and the requested corrosion resistance. Blasted surfaces are often used in industrial practice due to the easier and cheaper manufacturing process compared to pickled or electro-polished surfaces. Furthermore blasting with corundum-grain is more effective than blasting with glass-beads which also lower the process costs. In recent years, stainless steel surfaces showed an unusually high susceptibility to pitting corrosion after grinding with corundum. For this reason, it is now also questioned critically whether the corrosion resistance is influenced by the applied blasting agent. This question was specifically investigated by comparing grinded, pickled, corundum-grain- and glass-bead-blasted welding seams. Results of the SEM analyses of the blasting agents and the blasted surfaces will be presented and correlated with the different performed corrosion tests (potential measurement, KorroPad-test and pitting potential) on welding seams with different surface treatments.

  2. An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water

    NASA Astrophysics Data System (ADS)

    Lee, Han-Seung; Singh, Jitendra Kumar; Ismail, Mohamed A.

    2017-02-01

    A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance.

  3. The effect of fibre content, fibre size and alkali treatment to Charpy impact resistance of Oil Palm fibre reinforced composite material

    NASA Astrophysics Data System (ADS)

    Fitri, Muhamad; Mahzan, Shahruddin

    2016-11-01

    In this research, the effect of fibre content, fibre size and alkali treatment to the impact resistance of the composite material have been investigated, The composite material employs oil palm fibre as the reinforcement material whereas the matrix used for the composite materials are polypropylene. The Oil Palm fibres are prepared for two conditions: alkali treated fibres and untreated fibres. The fibre sizes are varied in three sizes: 5mm, 7mm and 10mm. During the composite material preparation, the fibre contents also have been varied into 3 different percentages: 5%, 7% and 10%. The statistical approach is used to optimise the variation of specimen determined by using Taguchi method. The results were analyzed also by the Taguchi method and shows that the Oil Palm fibre content is significantly affect the impact resistance of the polymer matrix composite. However, the fibre size is moderately affecting the impact resistance, whereas the fibre treatment is insignificant to the impact resistance of the oil palm fibre reinforced polymer matrix composite.

  4. Influence of the pulsed plasma treatment on the corrosion resistance of the low-alloy steel plated by Ni-based alloy

    NASA Astrophysics Data System (ADS)

    Dzhumaev, P.; Yakushin, V.; Kalin, B.; Polsky, V.; Yurlova, M.

    2016-04-01

    This paper presents investigation results of the influence of high temperature pulsed plasma flows (HTPPF) treatment on the corrosion resistance of low-alloy steel 0.2C-Cr-Mn- Ni-Mo cladded by the rapidly quenched nickel-based alloy. A technique that allows obtaining a defect-free clad layer with a good adhesion to the substrate was developed. It is shown that the preliminary treatment of steel samples by nitrogen plasma flows significantly increases their corrosion resistance in the conditions of intergranular corrosion test in a water solution of sulfuric acid. A change of the corrosion mechanism of the clad layer from intergranular to uniform corrosion was observed as a result of sub-microcrystalline structure formation and homogeneous distribution of alloying elements in the plasma treated surface layer thus leading to the significant increase of the corrosion resistance.

  5. Study on alkali removal technology from coal gasification gas

    SciTech Connect

    Inai, Motoko; Kajibata, Yoshihiro; Takao, Shoichi; Suda, Masamitsu

    1999-07-01

    The authors have proposed a new coal based combined cycle power plant concept. However, there are certain technical problems that must be overcome to establish this system. Major technical problem of the system is hot corrosion of gas turbine blades caused by sulfur and alkali vapor, because of high temperature dust removal without sulfur removal from the coal gas. So the authors have conducted several fundamental studies on dry type alkali removal sorbents for the purposed of reducing the corrosion on gas turbine blades. Based on the fundamental studies the authors found preferable alkali removal sorbents, and made clear their alkali removal performance.

  6. Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Jordi Perez; Marc Hornbostel; Kai-Hung Lau; Angel Sanjurjo

    2007-05-31

    Advanced electric power generation systems use a coal gasifier to convert coal to a gas rich in fuels such as H{sub 2} and CO. The gas stream contains impurities such as H{sub 2}S and HCl, which attack metal components of the coal gas train, causing plant downtime and increasing the cost of power generation. Corrosion-resistant coatings would improve plant availability and decrease maintenance costs, thus allowing the environmentally superior integrated-gasification-combined-cycle (IGCC) plants to be more competitive with standard power-generation technologies. Heat-exchangers, particle filters, turbines, and other components in the IGCC system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy will improve is resistance to such sulfidation attack and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. The Fe- and Ni-based high-temperature alloys are susceptible to sulfidation attack unless they are fortified with high levels of Cr, Al, and Si. To impart corrosion resistance, these elements need not be in the bulk of the alloy and need only be present at the surface layers. In this study, the use of corrosion-resistant coatings on low alloy steels was investigated for use as high-temperature components in IGCC systems. The coatings were deposited using SRI's fluidized-bed reactor chemical vapor deposition technique. Diffusion coatings of Cr and Al were deposited by this method on to dense and porous, low alloy stainless steel substrates. Bench-scale exposure tests at 900 C with a simulated coal gas stream containing 1.7% H{sub 2}S showed that the low alloy steels such SS405 and SS409 coated with {approx

  7. Corrosion and corrosion prevention in gas turbines

    NASA Technical Reports Server (NTRS)

    Mom, A. J. A.; Kolkman, H. J.

    1985-01-01

    The conditions governing the corrosion behavior in gas turbines are surveyed. Factors such as temperature, relative humidity, the presence of sulfur and nitrogen dioxide, and fuel quality are discussed. Electromechanical corrosion at relatively low temperature in compressors; oxidation; and hot corrosion (sulfidation) at high temperature in turbines are considered. Corrosion prevention by washing and rinsing, fueld additives, and corrosion resistant materials and coatings are reviewed.

  8. Influence of heat treatments on microstructure, mechanical properties, and corrosion resistance of weld alloy 625

    SciTech Connect

    Cortial, F.; Corrieu, J.M.; Vernot-Loier, C.

    1995-05-01

    The effects of heat treatments of the industrial type on the structural, mechanical, and corrosion resistance characteristics of weld alloy 625 have been studied. During the heat treatment, the mean concentration ratios of Nb, Mo, Si, Cr, Ni, and Fe elements between the interdendritic spaces and dendrite cores show little evolution up to 850 C. Beyond that temperature, this ratio approximates 1, and the composition heterogeneity has practically disappeared at 1,000 C. An eight-hour heat treatment at temperatures between 650 C and 750 C results in increased mechanical strength values and reduced ductility and impact strength linked to the precipitation of body-centered tetragonal metastable intermetallic {gamma}{double_prime} Ni{sub 3}Nb phase in the interdendritic spaces. An eight-hour treatment in the temperature range between 750 C and 950 C has catastrophic effects on all mechanical characteristics in relation with the precipitation, in the interdendritic spaces, of the stable orthorhombic intermetallic {delta} Ni{sub 3}(Nb, Mo, Cr, Fe, Ti) phase. At 1,000 C, the ductility and impact strength are restored. However, the higher the beat treatment temperature, the weaker the mechanical strength. Heat treatments have no effect on the pitting resistance of weld alloy 625 in sea water. The comparison of the results of this study on weld alloy 625 with those previously obtained on forged metal 625 shows that heat treatments below 650 C and above 1,000 C are the sole treatments to avoid embrittlement and impairment of the corrosion resistance characteristics of alloy 625.

  9. Influence of heat treatments on microstructure, mechanical properties, and corrosion resistance of weld alloy 625

    NASA Astrophysics Data System (ADS)

    Cortial, F.; Corrieu, J. M.; Vernot-Loier, C.

    1995-05-01

    The effects of heat treatments of the industrial type (eight-hour hold times at temperatures between 600 °C and 1000 °C) on the structural, mechanical, and corrosion resistance characteristics of weld alloy 625 have been studied. During the heat treatment, the mean concentration ratios of Nb, Mo, Si, Cr, Ni, and Fe elements between the interdendritic spaces and dendrite cores show little evolution up to 850 °C. Beyond that temperature, this ratio approximates 1, and the composition heterogeneity has practically disappeared at 1000 °C. An eight-hour heat treatment at temperatures between 650 °C and 750 °C results in increased mechanical strength values and reduced ductility and impact strength linked to the precipitation of body-centered tetragonal metastable intermetallic γ″ Ni3Nb phase in the interdendritic spaces. An eight-hour treatment in the temperature range between 750 °C and 950 °C has catastrophic effects on all mechanical characteristics in relation with the precipitation, in the interdendritic spaces, of the stable orthorhombic intermetallic δ Ni3(Nb, Mo, Cr, Fe, Ti) phase. At 1000 °C, the ductility and impact strength are restored. However, the higher the heat treatment temperature, the weaker the mechanical strength. Heat treatments have no effect on the pitting resistance of weld alloy 625 in sea water. The comparison of the results of this study on weld alloy 625 with those previously obtained on forged metal 625 shows that heat treatments below 650 °C and above 1000 °C are the sole treatments to avoid embrittlement and impairment of the corrosion resistance characteristics of alloy 625.

  10. Improvement of corrosion resistance and antibacterial effect of NiTi orthopedic materials by chitosan and gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Ahmed, Rasha A.; Fadl-allah, Sahar A.; El-Bagoury, Nader; El-Rab, Sanaa M. F. Gad

    2014-02-01

    Biocomposite consists of gold nanoparticles (AuNPs) and a natural polymer as Chitosan (CS) was electrodeposited over NiTi alloy to improve biocompatibility, biostability, surface corrosion resistance and antibacterial effect for orthopedic implantation. The forming process and surface morphology of this biocomposite coats over NiTi alloy were studied. The results showed that the nm-scale gold particles were embedded in the composite forming compact, thick and smooth coat. Elemental analysis revealed significant less Ni ion release from the coated NiTi alloy compared with the uncoated one by 20 fold. Furthermore, the electrochemical corrosion measurements indicated that AuNPs/CS composite coat was effective for improving corrosion resistance in different immersion times and at all pH values, which suggests that the coated NiTi alloys have potential for orthopedic applications. Additionally, the efficiencies of the biocomposite coats for inhibiting bacterial growth indicate high antibacterial effect.

  11. Corrosion resistance of multilayer hybrid sol-gel coatings deposited on the AISI 316L austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Caballero, Y. T.; Rondón, E. A.; Rueda, L.; Hernández Barrios, C. A.; Coy, A.; Viejo, F.

    2016-02-01

    In the present work multilayer hybrid sol-gel coatings were synthesized on the AISI 316L austenitic stainless steel employed in the fabrication of orthopaedic implants. Hybrid sols were obtained from a mixture of inorganic precursor, TEOS, and organic, GPTMS, using ethanol as solvent, and acetic acid as catalyst. The characterization of the sols was performed using pH measurements, rheological tests and infrared spectroscopy (FTIR) for different ageing times. On the other hand, the coatings were characterized by scanning electron microscopy (SEM), while the corrosion resistance was evaluated using anodic potentiodynamic polarization in SBF solution at 37±2°C. The results confirmed that sol-gel synthesis employing TEOS-GPTMS systems produces uniform and homogeneous coatings, which enhanced the corrosion resistance with regard to the parent alloy. Moreover, corrosion performance was retained after applying more than one layer (multilayer coatings).

  12. The effect of nitrogen ion implantation on the corrosion resistance and microstructure of tantalum-coated stainless steel

    NASA Astrophysics Data System (ADS)

    Eshghi, S.; Hanteh Zadeh, M.; Yari, M.; Jafari-Khamse, E.

    2014-06-01

    In this work, the effects of nitrogen ion implantation on the corrosion resistance and microstructure of DC magnetron sputtered tantalum-coated stainless steel were investigated. The nitrogen fluence was varied between 3-10 × 1017 ions/cm2 while the beam energy was kept constant at 30 keV. The effects of ion implantation were characterized by X-ray diffraction pattern, atomic force microscopy, and potentiodynamic corrosion test in a 0.5 MH2SO4 solution. The atomic force microscopy micrographs were quantitatively and statistically analyzed by computing the multifractal spectrum of the atomic force microscopy images. The results showed that the fluence variation strongly affected the surface roughness and formation of TaN and Ta2N phases. Increasing the nitrogen fluence up to 10 × 1017 ions/cm2 increased surface roughness. The highest corrosion resistance was obtained at 7 × 1017 ions/cm2 nitrogen fluence.

  13. Iron-Based Amorphous-Metals: High-Performance Corrosion-Resistant Materials (HPCRM) Development Final Report

    SciTech Connect

    Farmer, J C; Choi, J; Saw, C; Haslem, J; Day, D; Hailey, P; Lian, T; Rebak, R; Perepezko, J; Payer, J; Branagan, D; Beardsley, B; D'Amato, A; Aprigliano, L

    2009-03-16

    An overview of the High-Performance Corrosion-Resistant Materials (HPCRM) Program, which was co-sponsored by the Defense Advanced Research Projects Agency (DARPA) Defense Sciences Office (DSO) and the United States Department of Energy (DOE) Office of Civilian and Radioactive Waste Management (OCRWM), is discussed. Programmatic investigations have included a broad range of topics: alloy design and composition; materials synthesis; thermal stability; corrosion resistance; environmental cracking; mechanical properties; damage tolerance; radiation effects; and important potential applications. Amorphous alloys identified as SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) and SAM1651 (Fe{sub 48}Mo{sub 14}Cr{sub 15}Y{sub 2}C{sub 15}B{sub 6}) have been produced as melt-spun ribbons, drop-cast ingots and thermal-spray coatings. Chromium (Cr), molybdenum (Mo) and tungsten (W) additions provided corrosion resistance, while boron (B) enabled glass formation. Earlier electrochemical studies of melt-spun ribbons and ingots of these amorphous alloys demonstrated outstanding passive film stability. More recently thermal-spray coatings of these amorphous alloys have been made and subjected to long-term salt-fog and immersion tests. Good corrosion resistance has been observed during salt-fog testing. Corrosion rates were measured in situ with linear polarization, while simultaneously monitoring the open-circuit corrosion potentials. Reasonably good performance was observed. The sensitivity of these measurements to electrolyte composition and temperature was determined. The high boron content of this particular amorphous metal make this amorphous alloy an effective neutron absorber, and suitable for criticality control applications. In general, the corrosion resistance of these iron-based amorphous metals is maintained at operating temperatures up to the glass transition temperature. These materials are much harder than conventional

  14. Corrosion resistance of Ti modified by chitosan-gold nanoparticles for orthopedic implantation.

    PubMed

    Farghali, R A; Fekry, A M; Ahmed, Rasha A; Elhakim, H K A

    2015-08-01

    Highly uniform bionanocomposite film composed of chitosan (CS) and gold nanoparticles (AuNPs) was synthesized successfully by electrodeposition method. The influence of AuNPs/CS bionanocomposite film on corrosion resistance of Ti was investigated. Surface morphology and compositional properties of the bionanocomposite were analyzed by scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). Moreover, cyclic voltammetry (CV), open-circuit potential measurements (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (Rp) were used to examine the corrosion behavior in Hanks' solution. In comparison with Ti, Nyquist and Bode plots displayed higher impedance values and phase angles for AuNPs/CS biocomposite denoting a more protective passive film on Ti with inhibition efficiency (IE%) of 98%. An electric equivalent circuit with three time constants was modeled for the bionanocomposite. In addition, the antibacterial effect revealed the high efficiencies of the bionanocomposite film for inhibiting bacterial growth. The combination of the high biocompatibility of chitosan and strong adsorption ability of AuNPs make AuNPs/CS bionanocomposite promising candidate for modifying biomaterial surfaces for medical implantation applications.

  15. A facile electrodeposition process to fabricate corrosion-resistant superhydrophobic surface on carbon steel

    NASA Astrophysics Data System (ADS)

    Fan, Yi; He, Yi; Luo, Pingya; Chen, Xi; Liu, Bo

    2016-04-01

    Superhydrophobic Fe film with hierarchical micro/nano papillae structures is prepared on C45 steel surface by one-step electrochemical method. The superhydrophobic surface was measured with a water contact angle of 160.5 ± 0.5° and a sliding angle of 2 ± 0.5°. The morphology of the fabricated surface film was characterized by field emission scanning electron microscopy (FE-SEM), and the surface structure seems like accumulated hierarchical micro-nano scaled particles. Furthermore, according to the results of Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectroscopy (XPS), the chemical composition of surface film was iron complex with organic acid. Besides, the electrochemical measurements showed that the superhydrophobic surface improved the corrosion resistance of carbon steel in 3.5 wt.% NaCl solution significantly. The superhydrophobic layer can perform as a barrier and provide a stable air-liquid interface which inhibit penetration of corrosive medium. In addition, the as-prepared steel exhibited an excellent self-cleaning ability that was not favor to the accumulation of contaminants.

  16. The development of Ti alloys for dental implant with high corrosion resistance and mechanical strength.

    PubMed

    Yamazoe, Junichi; Nakagawa, Masaharu; Matono, Yoshinari; Takeuchi, Akari; Ishikawa, Kunio

    2007-03-01

    The corrosion behaviors of Ti and Ti-6Al-4V, Ti-6Al-7Nb, Ti-0.5Pt, Ti-6Al-4V-0.5Pt, and Ti-6Al-7Nb-0.5Pt alloys were examined using an electrochemical analyzer in artificial saliva containing 0.1 and 0.2% NaF at a pH of 4.0. The SEM observations revealed that the surfaces of the alloys containing 0.5 wt% Pt were not affected in fluoride-containing environments, whereas the surfaces of Ti, Ti-6A1-4V, and Ti-6Al-7Nb alloys were markedly rough. In artificial saliva containing 0.1% NaF at a pH of 4.0, the amounts of Ti dissolved from the Ti, Ti-6Al-4V, and Ti-6Al-7Nb alloys were about 50 times larger than those of the alloys containing 0.5 wt% Pt. The tensile strengths of the alloys containing 0.5 wt% Pt were equal to or higher than those of pure Ti or the alloys without Pt. The Ti-0.5Pt, Ti-6Al-4V-0.5Pt, and Ti-6Al-7Nb-0.5 alloys are expected to be useful in clinical dentistry as new Ti alloys with high corrosion resistance and mechanical strength.

  17. Effect of the deposition temperature on corrosion resistance and biocompatibility of the hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    Vladescu, A.; Braic, M.; Azem, F. Ak; Titorencu, I.; Braic, V.; Pruna, V.; Kiss, A.; Parau, A. C.; Birlik, I.

    2015-11-01

    Hydroxyapatite (HAP) ceramics belong to a class of calcium phosphate-based materials, which have been widely used as coatings on titanium medical implants in order to improve bone fixation and thus to increase the lifetime of the implant. In this study, HAP coatings were deposited from pure HAP targets on Ti6Al4V substrates using the radio-frequency magnetron sputtering technique at substrate temperatures ranging from 400 to 800 °C. The surface morphology and the crystallographic structure of the films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistance of the coatings in saliva solution at 37 °C was evaluated by potentiodynamic polarization. Additionally, the human osteosarcoma cell line (MG-63) was used to test the biocompatibility of the coatings. The results showed that all of the coatings grown uniformly and that the increasing substrate temperature induced an increase in their crystallinity. Corrosion performance of the coatings was improved with the increase of the substrate temperature from 400 °C to 800 °C. Furthermore, all the coatings support the attachment and growth of the osteosarcoma cells with regard to the in vitro test findings.

  18. Corrosion resistance of pseudo-spin-valve systems: Pd vs. Ta capping layers

    NASA Astrophysics Data System (ADS)

    Matthes, P.; Albrecht, M.

    2016-08-01

    An analysis of both magnetic and magneto-transport properties in dependence of the corrosion resistance is presented for a pseudo-spin-valve (PSV) system with different capping layers. The magnetoresistive part of the sample consists of a [Co/Pd] multilayer with perpendicular magnetic anisotropy and a single Co layer with in-plane easy axis separated by a Cu spacer, forming a PSV system with crossed anisotropies. The samples were annealed under ambient conditions up to temperatures of 200 °C to facilitate the corrosion process. Whereas the magnetic properties are stable up to 100 °C independent of the capping layer, the giant magnetoresistance (GMR) effect is more sensitive on annealing. In case of Pd as capping layer, the GMR of the pseudo-spin-valve considerably degrades already after annealing at 60 °C, whereby even by thickening of the Pd layer up to 10 nm, no pronounced improvement was obtained. On the contrary, for Ta as capping layer the GMR ratio stays constant upon heating up to 100 °C, followed by a comparable moderate decay for even higher annealing temperatures.

  19. Computer Simulation and Experimental Validation on the Oxidation and Sulfate Corrosion Resistance of Novel Chromium Based High Temperature Alloys

    SciTech Connect

    Yang, Shizhong

    2013-02-28

    This report summarizes our recent works of ab initio molecular dynamics inter-atomic potentials development on dilute rare earth element yttrium (Y) etc. doped chromium (Cr) alloy systems, its applications in oxidation and corrosion resistance simulation, and experiment validation on the candidate systems. The simulation methods, experimental validation techniques, achievements already reached, students training, and future improvement are briefly introduced.

  20. Zirconium alloys with small amounts of iron and copper or nickel show improved corrosion resistance in superheated steam

    NASA Technical Reports Server (NTRS)

    Greenberg, S.; Youngdahl, C. A.

    1967-01-01

    Heat treating various compositions of zirconium alloys improve their corrosion resistance to superheated steam at temperatures higher than 500 degrees C. This increases their potential as fuel cladding for superheated-steam nuclear-fueled reactors as well as in autoclaves operating at modest pressures.

  1. 75 FR 25841 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-10

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...'') published a notice of initiation of the administrative review of the antidumping duty order on...

  2. 76 FR 17381 - Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Notice of Final Results of the Sixteenth Administrative Review Correction In notice document...

  3. 76 FR 21332 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...'') published a notice of initiation of the administrative review of the antidumping duty order on...

  4. 77 FR 25405 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-30

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...'') published a notice of initiation of the administrative review of the antidumping duty order on...

  5. Corrosion resistance of a laser spot-welded joint of NiTi wire in simulated human body fluids.

    PubMed

    Yan, Xiao-Jun; Yang, Da-Zhi

    2006-04-01

    The purpose of this study was to investigate corrosion resistance of a laser spot-welded joint of NiTi alloy wires using potentiodynamic tests in Hank's solution at different PH values and the PH 7.4 NaCl solution for different Cl- concentrations. Scanning electron microscope observations were carried out before and after potentiodynamic tests. The composition of a laser spot-welded joint and base metal were characterized by using an electron probe microanalyzer. The results of potentiodynamic tests showed that corrosion resistance of a laser spot-welded joint of NiTi alloy wire was better than that of base metal, which exhibited a little higher breakdown potential and passive range, and a little lower passive current density. Corrosion resistances of a laser spot-welded joint and base metal decreased with increasing of the Cl- concentration and PH value. The improvement of corrosion resistance of the laser spot-welded joint was due to the decrease of the surface defects and the increase of the Ti/Ni ratio.

  6. Development of Advanced Corrosion-Resistant Fe-Cr-Ni Austenitic Stainless Steel Alloy with Improved High Temperature Strenth and Creep-Resistance

    SciTech Connect

    Maziasz, PJ

    2004-09-30

    In February of 1999, a Cooperative Research and Development Agreement (CRADA) was undertaken between Oak Ridge National Laboratory (ORNL) and Special Metals Corporation-Huntington Alloys (formerly INCO Alloys International, Inc.) to develop a modified wrought austenitic stainless alloy with considerably more strength and corrosion resistance than alloy 800H or 800HT, but with otherwise similar engineering and application characteristics. Alloy 800H and related alloys have extensive use in coal flue gas environments, as well as for tubing or structural components in chemical and petrochemical applications. The main concept of the project was make small, deliberate elemental microalloying additions to this Fe-based alloy to produce, with proper processing, fine stable carbide dispersions for enhanced high temperature creep-strength and rupture resistance, with similar or better oxidation/corrosion resistance. The project began with alloy 803, a Fe-25Cr-35NiTi,Nb alloy recently developed by INCO, as the base alloy for modification. Smaller commercial developmental alloy heats were produced by Special Metals. At the end of the project, three rounds of alloy development had produced a modified 803 alloy with significantly better creep resistance above 815EC (1500EC) than standard alloy 803 in the solution-annealed (SA) condition. The new upgraded 803 alloy also had the potential for a processing boost in that creep resistance for certain kinds of manufactured components that was not found in the standard alloy. The upgraded 803 alloy showed similar or slightly better oxidation and corrosion resistance relative to standard 803. Creep strength and oxidation/corrosion resistance of the upgraded 803 alloy were significantly better than found in alloy 800H, as originally intended. The CRADA was terminated in February 2003. A contributing factor was Special Metals Corporation being in Chapter 11 Bankruptcy. Additional testing, further commercial scale-up, and any potential

  7. Robust Slippery Coating with Superior Corrosion Resistance and Anti-Icing Performance for AZ31B Mg Alloy Protection.

    PubMed

    Zhang, Jialei; Gu, Changdong; Tu, Jiangping

    2017-03-29

    Biomimetic slippery liquid-infused porous surfaces (SLIPSs) are developed as a potential alternative to superhydrophobic surfaces (SHSs) to resolve the issues of poor durability in corrosion protection and susceptibility to frosting. Herein, we fabricated a double-layered SLIPS coating on the AZ31 Mg alloy for corrosion protection and anti-icing application. The porous top layer was infused by lubricant, and the compact underlayer was utilized as a corrosion barrier. The water-repellent SLIPS coating exhibits a small sliding angle and durable corrosion resistance compared with the SHS coating. Moreover, the SLIPS coating delivers durable anti-icing performance for the Mg alloy substrate, which is obviously superior to the SHS coating. Multiple barriers in the SLIPS coating, including the infused water-repellent lubricant, the self-assembled monolayers coated porous top layer, and the compact layered double hydroxide-carbonate composite underlayer, are suggested as being responsible for the enhanced corrosion resistance and anti-icing performance. The robust double-layered SLIPS coating should be of great importance to expanding the potential applications of light metals and their alloys.

  8. Optimum temperature on corrosion resistance for plasma ion nitrided 316L stainless steel in sea water solution

    NASA Astrophysics Data System (ADS)

    Chong, Sang-Ok; Kim, Seong-Jong

    2017-01-01

    The aim of this research is to investigate the optimum plasma ion nitriding temperature on corrosion resistance in natural sea water for plasma ion nitrided 316L stainless steel. Plasma ion nitriding was conducted at different temperatures of 350, 400, 450, and 500 °C with a mixture of 75% of nitrogen and 25% of hydrogen during 10 h. In conclusion of anodic polarization test, a wide passive potential region and a high corrosion potential were observed at a plasma ion nitriding temperature of 450 °C. Moreover, relatively less damage depth and clean surface micrographs were observed at 450 °C as results of observation of three-dimensional (3D) microscope and scanning electron microscope (SEM) after polarization experiments. In addition, higher corrosion potential and lower corrosion current density were indicated at plasma ion nitrided samples than the value of untreated substrate after Tafel analysis. Hence, plasma ion nitrided at 450 °C in sea water solution represented optimum corrosion resistance among the all the plasma ion nitriding temperature parameters.

  9. Corrosion resistance and behavior of construction materials exposed to dilute sulfuric acid at elevated temperatures under static conditions

    SciTech Connect

    Nguyen, D.T.

    1994-10-01

    Laboratory investigation has been undertaken to determine the electrochemical behavior and corrosion resistance of various construction materials in a simulated hydrolysis environment (5 wt % sulfuric acid) at temperatures ranging from 90 to 220C. Tests were performed in an autoclave-type electrochemical cell. The corrosion behavior of the test materials was determined using computer-controlled DC potentiodynamic polarization. Corrosion rates of the test materials were determined using AC impedance techniques. Among the stainless steels tested, only alloy N08026 (Carpenter 20Mo-6) performed satisfactory up to a temperature of 100C. The alloy passivated spontaneously in the environment and corroded at a rate of less than 2 mpy. None of the stainless steels tested could be used at 120{degrees}C or above. A number of nickel-based alloys tested had good corrosion resistance up to 100C, but their corrosion rate exceeded 2 mpy at higher temperatures. Zirconium alloys were satisfactory up to 180C. Only tantalum and a tantalum-niobium alloy were satisfactory up to 220C.

  10. Synergistic Effect of Superhydrophobicity and Oxidized Layers on Corrosion Resistance of Aluminum Alloy Surface Textured by Nanosecond Laser Treatment.

    PubMed

    Boinovich, Ludmila B; Emelyanenko, Alexandre M; Modestov, Alexander D; Domantovsky, Alexandr G; Emelyanenko, Kirill A

    2015-09-02

    We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed.

  11. Corrosion resistance and cytocompatibility of biodegradable surgical magnesium alloy coated with hydrogenated amorphous silicon.

    PubMed

    Xin, Yunchang; Jiang, Jiang; Huo, Kaifu; Tang, Guoyi; Tian, Xiubo; Chu, Paul K

    2009-06-01

    The fast degradation rates in the physiological environment constitute the main limitation for the applications of surgical magnesium alloys as biodegradable hard-tissue implants. In this work, a stable and dense hydrogenated amorphous silicon coating (a-Si:H) with desirable bioactivity is deposited on AZ91 magnesium alloy using magnetron sputtering deposition. Raman spectroscopy and Fourier transform infrared spectroscopy reveal that the coating is mainly composed of hydrogenated amorphous silicon. The hardness of the coated alloy is enhanced significantly and the coating is quite hydrophilic as well. Potentiodynamic polarization results show that the corrosion resistance of the coated alloy is enhanced dramatically. In addition, the deterioration process of the coating in simulated body fluids is systematically investigated by open circuit potential evolution and electrochemical impedance spectroscopy. The cytocompatibility of the coated Mg is evaluated for the first time using hFOB1.19 cells and favorable biocompatibility is observed.

  12. Method for providing uranium articles with a corrosion-resistant anodized coating

    DOEpatents

    Waldrop, F.B.; Washington, C.A.

    1981-01-07

    Uranium articles are provided with anodized oxide coatings in an aqueous solution of an electrolyte selected from the group consisting of potassium phosphate, potassium hydroxide, ammonium hydroxide, and a mixture of potassium tetraborate and boric acid. The uranium articles are anodized at a temperature greater than about 75/sup 0/C with a current flow of less than about 0.036 A/cm/sup 2/ of surface area while the pH of the solution is maintained in a range of about 2 to 11.5. The pH values of the aqueous solution and the low current density utilized during the electrolysis prevent excessive dissolution of the uranium and porosity in the film or watering. The relatively high temperature of the electrolyte bath inhibits hydration and the attendant deleterious pitting so as to enhance corrosion resistance of the anodized coating.

  13. Method for providing uranium articles with a corrosion resistant anodized coating

    DOEpatents

    Waldrop, Forrest B.; Washington, Charles A.

    1982-01-01

    Uranium articles are provided with anodized oxide coatings in an aqueous solution of an electrolyte selected from the group consisting of potassium phosphate, potassium hydroxide, ammonium hydroxide, and a mixture of potassium tetraborate and boric acid. The uranium articles are anodized at a temperature greater than about 75.degree. C. with a current flow of less than about 0.036 A/cm.sup.2 of surface area while the pH of the solution is maintained in a range of about 2 to 11.5. The pH values of the aqueous solution and the low current density utilized during the electrolysis prevent excessive dissolution of the uranium and porosity in the film or watering. The relatively high temperature of the electrolyte bath inhibits hydration and the attendant deleterious pitting so as to enhance corrosion resistance of the anodized coating.

  14. Method For Creating Corrosion Resistant Surface On An Aluminum Copper Alloy

    DOEpatents

    Mansfeld, Florian B.; Wang, You; Lin, Simon H.

    1997-06-03

    A method for treating the surface of aluminum alloys hang a relatively high copper content is provided which includes the steps of removing substantially all of the copper from the surface, contacting the surface with a first solution containing cerium, electrically charging the surface while contacting the surface in an aqueous molybdate solution, and contacting the surface with a second solution containing cerium. The copper is substantially removed from the surface in the first step either by (i) contacting the surface with an acidic chromate solution or by (ii) contacting the surface with an acidic nitrate solution while subjecting the surface to an electric potential. The corrosion-resistant surface resulting from the invention is excellent, consistent and uniform throughout the surface. Surfaces treated by the invention may often be certified for use in salt-water services.

  15. Influence of hydroxyapatite on the corrosion resistance of the Ti-13Nb-13Zr alloy.

    PubMed

    Duarte, Laís T; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

    2009-05-01

    Electrochemical analyses on the biocompatible alloy Ti-13Nb-13Zr wt% in an electrolyte simulating physiological medium (PBS solution) are reported. Hydroxyapatite (HA) films were obtained on the alloy by electrodeposition at constant cathodic current. Samples of the alloy covered with an anodic-oxide film or an anodic-oxide/HA film were analyzed by open circuit potential and electrochemical impedance spectroscopy measurements during 180 days in the PBS electrolyte. Analyses of the open-circuit potential (E (oc)) values indicated that the oxide/HA film presents better protection characteristics than the oxide only. This behavior was corroborated by the higher film resistances obtained from impedance data, indicating that, besides improving the alloy osteointegration, the hydroxyapatite film may also increase the corrosion protection of the biomaterial.

  16. Pulsed ion beam surface treatment for preparing rapidly solidified corrosion resistant steel and aluminum surfaces

    SciTech Connect

    Buchheit, R.G.; Maestas, L.M.; McIntyre, D.C.; Stinnett, R.W.; Greenly, J.B.

    1995-03-01

    Intense, pulsed ion beams were used to melt and rapidly resolidify Types 316F, 316L and sensitized 304 stainless steel surfaces to eliminate the negative effects of microstructural heterogeneity on localized corrosion resistance. Anodic polarization curves determined for 316F and 316L showed that passive current densities were reduced and pitting potentials were increased due to ion beam treatment. Type 304 samples sensitized at 600 C for 100 h showed no evidence of grain boundary attack when surfaces were ion beam treated. Equivalent ion beam treatments were conducted with a 6061-T6 aluminum alloy. Electrochemical impedance experiments conducted with this alloy exposed to an aerated chloride solution showed that the onset of pitting was delayed compared to untreated control samples.

  17. Long term corrosion resistance of alumina forming austenitic stainless steels in liquid lead

    NASA Astrophysics Data System (ADS)

    Ejenstam, Jesper; Szakálos, Peter

    2015-06-01

    Alumina forming austenitic steels (AFA) and commercial stainless steels have been exposed in liquid lead with 10-7 wt.% oxygen at 550 °C for up to one year. It is known that chromia forming austenitic stainless steels, such as 316L and 15-15 Ti, have difficulties forming protective oxides in liquid lead at temperatures above 500 °C, which is confirmed in this study. By adding Al to austenitic steels, it is in general terms possible to increase the corrosion resistance. However this study shows that the high Ni containing AFA alloys are attacked by the liquid lead, i.e. dissolution attack occurs. By lowering the Ni content in AFA alloys, it is possible to achieve excellent oxidation properties in liquid lead. Following further optimization of the microstructural properties, low Ni AFA alloys may represent a promising future structural steel for lead cooled reactors.

  18. Laser-Assisted Cold-Sprayed Corrosion- and Wear-Resistant Coatings: A Review

    NASA Astrophysics Data System (ADS)

    Olakanmi, E. O.; Doyoyo, M.

    2014-06-01

    Laser-assisted cold spray (LACS) process will be increasingly employed for depositing coatings because of its unique advantages: solid-state deposition of dense, homogeneous, and pore-free coatings onto a range of substrates; and high build rate at reduced operating costs without the use of expensive heating and process inert gases. Depositing coatings with excellent performance indicators via LACS demands an accurate knowledge and control of processing and materials' variables. By varying the LACS process parameters and their interactions, the functional properties of coatings can be manipulated. Moreover, thermal effect due to laser irradiation and microstructural evolution complicate the interpretation of LACS mechanical deformation mechanism which is essential for elucidating its physical phenomena. In order to provide a basis for follow-on-research that leads to the development of high-productivity LACS processing of coatings, this review focuses on the latest developments in depositing corrosion- and wear-resistant coatings with the emphasis on the composition, structure, and mechanical and functional properties. Historical developments and fundamentals of LACS are addressed in an attempt to describe the physics behind the process. Typical technological applications of LACS coatings are also identified. The investigations of all process sequences, from laser irradiation of the powder-laden gas stream and the substrate, to the impingement of thermally softened particles on the deposition site, and subsequent further processes, are described. Existing gaps in the literature relating to LACS-dependent microstructural evolution, mechanical deformation mechanisms, correlation between functional properties and process parameters, processing challenges, and industrial applications have been identified in order to provide insights for further investigations and innovation in LACS deposition of wear- and corrosion-resistant coatings.

  19. In-situ contact electrical resistance technique for investigating corrosion inhibitor adsorption on copper electrodes

    SciTech Connect

    Moretti, G.; Quartarone, G.; Zingales, A.; Molokanov, V.V.

    1998-02-01

    Traditional electrochemical tests and the contact electrical resistance technique (CER) were used to investigate the effect on corrosion of pure copper (99.999 wt%) of adding benzotriazole (BTA) and 1-hydroxybenzotriazone (1-OH-BTA) to acidic solutions (sulfuric acid [H{sub 2}SO{sub 4}], pH = 1.7, and sodium sulfate [Na{sub 2}SO{sub 4}] until total sulfate [SO{sub 4}{sup 2{minus}}] concentration = 0.1 M). This technique permitted growth of oxide and/or salt films as well as adsorption of the organic inhibitors on the copper surface to be evaluated. Formation of copper oxide ([Cu{sub 2}O]{sub 2})., sulfate (CuSo{sub 4}{center_dot}5H{sub 2}O), thiocyanate (CuSCN), and halogenyde (CuI, CuBr, and CuCl) films on copper electrodes was followed in situ in sulfate solutions at various pH values under low overpotentials. Effects of pH, solution anion content, and/or the amount of BTA or 1-OH-BTA on electrical resistance (R) of the surface films formed on pure copper electrodes were treated. BTA acted as a more efficient corrosion inhibitor than 1-OH-BTA, reaching inhibition percentages (IP) of {approximately}90% compared to those of 1-OH-BTA, which reached a maximum of {approximately}76% in 2 {times} 10{sup {minus}3} M solutions. It was possible to distinguish between maximum R of the surface film, found in solutions containing BTA, associated with the adsorption of neutral inhibitor molecules, and the sharp rise in R attributable to [Cu(BTA)]{sub n} complex formation.

  20. Corrosion resistant coatings for silicon carbide heat exchanger tubes -- Volume 3. Final report

    SciTech Connect

    Boss, D.E.

    1996-06-07

    The development of a silicon carbide (SiC) heat exchanger is a critical step in the development of the Externally-Fired Combined Cycle (EFCC) power system. SiC is the only material that provides the necessary combination of resistance to creep, thermal shock, and oxidation. While the SiC structure materials provide the thermomechanical and thermophysical properties needed for an efficient system, the mechanical properties of the SiC tubes are severely degraded through corrosion by the coal combustion products. To obtain the necessary service life of thousands of hours at temperature, a protective coating is needed that is stable with both the SiC tube and the coal combustion products, resists erosion from the particle laden gas stream, is thermal shock resistant, adheres to SiC during repeated thermal shocks (start-up, process upsets, shut-down), and allows the EFCC system to be cost competitive. This demanding set of technical performance and cost drivers was used in reviewing and selecting candidate protective materials. After a review of open literature, discussion with leading researchers in materials for coal combustion environments, and preliminary thermodynamic studies, a total of ten materials were identified for future study that were grouped into three categories: alumina-based materials, materials stable with SiO{sub 2}, and low expansion materials.

  1. Influence of hardening and surface modification of endourological wires on corrosion resistance.

    PubMed

    Walke, Witold; Przondziono, Joanna

    2012-01-01

    Guide wires with suitable functional characteristics are of crucial importance for proper urological treatment. This study presents an analysis of the effect of work hardening taking place in the process of wire cold drawing and the effect of surface modification by means of electrochemical polishing and chemical passivation on the resistance of wires made of X10CrNi18-8 steel used in urology. Corrosion resistance was evaluated on the grounds of the registered anodic polarisation curves by means of potentiodynamic method. The tests were made in solution simulating human urine. Anodic polarisation curves were presented for selected wire diameters. Mechanical properties were tested in a static uniaxial tensile test. The course of flow curve as well as mathematical form of flow stress function were determined. Curves presenting the relation of polarisation resistance as a function of strain applied in the drawing process are given. The tests carried out show that surface modification by means of electrochemical polishing and then chemical passivation of wires used in endourological treatment is fundamental.

  2. Dual wavelength laser beam alloying of aluminium alloy for enhanced corrosion resistance

    SciTech Connect

    Liu, Z.; Watkins, K.G.; Steen, W.M.; Vilar, R.; Ferreira, M.G.

    1997-08-01

    Aluminum alloys are known for their poor resistance to localized attack and, in particular, for pitting in chloride-containing electrolytes. In this paper, improvement of the pitting corrosion resistance of 2014-T6 aluminum alloy has been investigated by means of laser surface alloying of Cr into the substrate. Since aluminum is highly reflective and thermally conductive material, it is often difficult to process with laser beams. Oxide films on the surface can prevent surface alloying as with the case of Cr alloying into aluminum by in-situ powder feeding. This work describes a new technique using mixed excimer laser and CO{sub 2} laser beam processing to generate a Cr alloyed layer on a 2014 aluminum alloy substrate. It is shown that improvement of alloying homogeneity following in-situ powder feeding can be achieved with mixed beam processing. Conditions under which this can be achieved have been studied and the effect of laser processing parameters on the surface roughness, oxidation and absorption is discussed. Microstructural and surface morphological analysis using optical microscopy, scanning electron microscopy and energy dispersive spectroscopy are also discussed. The electrochemical behavior of the treated samples in de-aerated 1 M NaCl solution has also been studied and has indicated that an improvement of pitting resistance by laser surface treatment can be achieved.

  3. Cyclotriphosphazene and TiO2 reinforced nanocomposite coated on mild steel plates for antibacterial and corrosion resistance applications

    NASA Astrophysics Data System (ADS)

    Krishnadevi, Krishnamoorthy; Selvaraj, Vaithilingam

    2016-03-01

    The mild steel surface has been modified to impart anticorrosion and antibacterial properties through a dip coating method followed by thermal curing of a mixture containing amine terminated cyclotriphosphazene and functionalized titanium dioxide nanoparticles reinforced benzoxazine based cyanate ester composite (ATCP/FTiO2/Bz-CE). The corrosion resistance behavior of coating material has been investigated by electrochemical and antibacterial studies by disc diffusion method. The nanocomposites coated mild steels have displayed a good chemical stability over long immersion in a corrosive environment. The protection efficiency has found to be high for ATCP/FTiO2/Bz-CE composites, which can be used in microelectronics and marine applications.

  4. Peculiarities of the influence of hot deformation and heat treatment on the corrosion resistance of aluminum alloys

    SciTech Connect

    Rabinovich, M.Kh.; Trifonov, V.G.

    1998-07-03

    The question about the influence of superplastic deformation (SPD) on mechanical properties of materials and the reliability of articles made out of these materials was studied sufficiently thoroughly. However, the information about the influence of microcrystalline (MC) structure processed by SPD on corrosion properties is rather limited. In respect to aluminum alloys this question was considered in some works. As known, the corrosion resistance plays a significant role in determining such an important aspect of reliability as endurance. The present paper is devoted to this problem.

  5. Demonstration of Corrosion-Resistant Coatings for Air-Conditioning Coils and Fins

    DTIC Science & Technology

    2015-06-01

    cost effectiveness of two of the newer coatings to protect build- ing air-conditioning condenser evaporator coils and fins from corrosion . Exposure...on-site coupons under this test be periodically revisited over the next 30 years, and the corrosion - protection performance of the two coating ...quality coating (such as the demonstrated technologies) would protect aluminum from corrosion , even in more corrosive atmospheres. Clearly, each of the

  6. Optimization of the HOVF Spray Parameters by Taguchi Method for High Corrosion-Resistant Fe-Based Coatings

    NASA Astrophysics Data System (ADS)

    Qin, Yujiao; Wu, Yuping; Zhang, Jianfeng; Hong, Sheng; Guo, Wenmin; Chen, Liyan; Liu, Hao

    2015-07-01

    Taguchi method was used to optimize the parameters of the high velocity oxygen fuel (HVOF) spray process and obtain the high corrosion-resistant Fe-based coatings. Based on the signal-to-noise ( S/ N) ratio and the analysis of variance, the significance of spray parameters in determining the porosity of the coatings was found to be in the order of spray distance, oxygen flow, and kerosene flow. Thus, the optimal parameters for the porosity of the HVOF sprayed Fe-based coating were determined as 280 mm for the spray distance, 963 scfh for the oxygen flow, and 28 gph for the kerosene flow. The potentiodynamic polarization and EIS tests indicated that the Fe-based coating prepared with the optimal parameters exhibited a higher corrosion potential ( E corr) of -196.14 mV, a lower corrosion current density ( i corr) of 0.14 μA/cm2, and a higher coating resistance ( R c) of 2.26 × 106 Ω cm2 than those of the hard chromium coating in 3.5% sodium chloride solution. This superior corrosion resistance could be attributed to the dense structure with low porosity and partially amorphous phases of the Fe-based coatings.

  7. Evaluation of corrosion resistance of implant-use Ti-Zr binary alloys with a range of compositions.

    PubMed

    Akimoto, Teisuke; Ueno, Takeshi; Tsutsumi, Yusuke; Doi, Hisashi; Hanawa, Takao; Wakabayashi, Noriyuki

    2016-11-18

    Although titanium-zirconium (Ti-Zr) alloy has been adopted for clinical applications, the ideal proportion of Zr in the alloy has not been identified. In this study, we investigated the biocompatibility of Ti-Zr alloy by evaluating its corrosion resistance to better understand whether there is an optimal range or value of Zr proportion in the alloy. We prepared pure Ti, Ti-30Zr, Ti-50Zr, Ti-70Zr, and pure Zr (mol% of Zr) samples and subjected them to anodic polarization and immersion tests in a lactic acid + sodium chloride (NaCl) solution and artificial saliva. We observed pitting corrosion in the Ti-70Zr and Zr after exposure to both solutions. After the immersion test, we found that pure Ti exhibited the greatest degree of dissolution in the lactic acid + NaCl solution, with the addition of Zr dramatically reducing Ti ion dissolution, with the reduction ultimately exceeding 90% in the case of the Ti-30Zr. Hence, although the localized corrosion resistance under severe conditions was compromised when the Zr content was more than 70%, metal ion release reduced owing to Zr addition and the corresponding formation of a stable passive layer. The results suggest that Ti-30Zr or a Zr proportion of less than 50% would offer an ideal level of corrosion resistance for clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  8. Development in corrosion resistance by microstructural refinement in Zr-16 SS 304 alloy using suction casting technique

    SciTech Connect

    Das, N. Sengupta, P.; Abraham, G.; Arya, A.; Kain, V.; Dey, G.K.

    2016-08-15

    Highlights: • Grain refinement was made in Zr–16 wt.% SS alloy while prepared by suction casting process. • Distribution of Laves phase, e.g., Zr{sub 2}(Fe, Cr) was raised in suction cast (SC) Zr–16 wt.% SS. • Corrosion resistance was improved in SC alloy compared to that of arc-melt-cast alloy. • Grain refinement in SC alloy assisted for an increase in its corrosion resistance. - Abstract: Zirconium (Zr)-stainless steel (SS) hybrid alloys are being considered as baseline alloys for developing metallic-waste-form (MWF) with the motivation of disposing of Zr and SS base nuclear metallic wastes. Zr–16 wt.% SS, a MWF alloy optimized from previous studies, exhibit significant grain refinement and changes in phase assemblages (soft phase: Zr{sub 2}(Fe, Cr)/α-Zr vs. hard phase: Zr{sub 3}(Fe, Ni)) when prepared by suction casting (SC) technique in comparison to arc-cast-melt (AMC) route. Variation in Cr-distribution among different phases are found to be low in suction cast alloy, which along with grain refinement restricted Cr-depletion at the Zr{sub 2}(Fe, Cr)/Zr interfaces, prone to localized attack. Hence, SC alloy, compared to AMC alloy, showed lower current density, higher potential at the breakdown of passivity and higher corrosion potential during polarization experiments (carried out under possible geological repository environments, viz., pH 8, 5 and 1) indicating its superior corrosion resistance.

  9. Metallic copper corrosion rates, moisture content, and growth medium influence survival of copper ion-resistant bacteria.

    PubMed

    Elguindi, Jutta; Moffitt, Stuart; Hasman, Henrik; Andrade, Cassandra; Raghavan, Srini; Rensing, Christopher

    2011-03-01

    The rapid killing of various bacteria in contact with metallic copper is thought to be influenced by the influx of copper ions into the cells, but the exact mechanism is not fully understood. This study showed that the kinetics of contact killing of copper surfaces depended greatly on the amount of moisture present, copper content of alloys, type of medium used, and type of bacteria. We examined antibiotic- and copper ion-resistant strains of Escherichia coli and Enterococcus faecium isolated from pig farms following the use of copper sulfate as feed supplement. The results showed rapid killing of both copper ion-resistant E. coli and E. faecium strains when samples in rich medium were spread in a thin, moist layer on copper alloys with 85% or greater copper content. E. coli strains were rapidly killed under dry conditions, while E. faecium strains were less affected. Electroplated copper surface corrosion rates were determined from electrochemical polarization tests using the Stern-Geary method and revealed decreased corrosion rates with benzotriazole and thermal oxide coating. Copper ion-resistant E. coli and E. faecium cells suspended in 0.8% NaCl showed prolonged survival rates on electroplated copper surfaces with benzotriazole coating and thermal oxide coating compared to surfaces without anti-corrosion treatment. Control of surface corrosion affected the level of copper ion influx into bacterial cells, which contributed directly to bacterial killing.

  10. Study made of corrosion resistance of stainless steel and nickel alloys in nuclear reactor superheaters

    NASA Technical Reports Server (NTRS)

    Greenberg, S.; Hart, R. K.; Lee, R. H.; Ruther, W. E.; Schlueter, R. R.

    1967-01-01

    Experiments performed under conditions found in nuclear reactor superheaters determine the corrosion rate of stainless steel and nickel alloys used in them. Electropolishing was the primary surface treatment before the corrosion test. Corrosion is determined by weight loss of specimens after defilming.

  11. Corrosion resistance of enamel coating modified by calcium silicate and sand particle for steel reinforcement in concrete

    NASA Astrophysics Data System (ADS)

    Tang, Fujian

    Porcelain enamel has stable chemical property in harsh environments such as high temperature, acid and alkaline, and it can also chemically react with substrate reinforcing steel resulting in improved adherence strength. In this study, the corrosion resistances of enamel coating modified by calcium silicate and sand particles, which are designed for improved bond strength with surrounding concrete, were investigated in 3.5 wt% NaCl solution. It consists of two papers that describe the results of the study. The first paper investigates the corrosion behavior of enamel coating modified by calcium silicate applied to reinforcing steel bar in 3.5 wt% NaCl solution by OCP, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The coatings include a pure enamel, a mixed enamel that consists of 50% pure enamel and 50% calcium silicate by weight, and a double enamel that has an inner pure enamel layer and an outer mixed enamel layer. Electrochemical tests demonstrates that both pure and double enamel coatings can significantly improve corrosion resistance, while the mixed enamel coating offers very little protection due to connected channels. The second paper is focused on the electrochemical characteristics of enamel coating modified by sand particle applied to reinforcing steel bar in 3.5 wt% NaCl solution by EIS. Six percentages by weight are considered including 5%, 10%, 20%, 30%, 50%, and 70%. Results reveal that addition of sand particle does not affect its corrosion resistance significantly. Most of the sand particles can wet very well with enamel body, while some have a weak zone which is induced during the cooling stage due to different coefficient of thermal expansion. Therefore, quality control of sand particle is the key factor to improve its corrosion resistance.

  12. Effect of annealing temperature on the pitting corrosion resistance of super duplex stainless steel UNS S32750

    SciTech Connect

    Tan Hua; Jiang Yiming; Deng Bo; Sun Tao; Xu Juliang; Li Jin

    2009-09-15

    The pitting corrosion resistance of commercial super duplex stainless steels SAF2507 (UNS S32750) annealed at seven different temperatures ranging from 1030 deg. C to 1200 deg. C for 2 h has been investigated by means of potentiostatic critical pitting temperature. The microstructural evolution and pit morphologies of the specimens were studied through optical/scanning electron microscope. Increasing annealing temperature from 1030 deg. C to 1080 deg. C elevates the critical pitting temperature, whereas continuing to increase the annealing temperature to 1200 deg. C decreases the critical pitting temperature. The specimens annealed at 1080 deg. C for 2 h exhibit the best pitting corrosion resistance with the highest critical pitting temperature. The pit morphologies show that the pit initiation sites transfer from austenite phase to ferrite phase as the annealing temperature increases. The aforementioned results can be explained by the variation of pitting resistance equivalent number of ferrite and austenite phase as the annealing temperature changes.

  13. Pitting corrosion resistance of nickel-titanium rotary instruments with different surface treatments in seventeen percent ethylenediaminetetraacetic Acid and sodium chloride solutions.

    PubMed

    Bonaccorso, Antonio; Tripi, Teresa Roberta; Rondelli, Gianni; Condorelli, Guglielmo Guido; Cantatore, Giuseppe; Schäfer, Edgar

    2008-02-01

    This study evaluated the pitting corrosion resistance of nickel-titanium (NiTi) rotary instruments with different surface treatments in 17% ethylenediaminetetraacetic acid (EDTA) and NaCl solutions. Electropolished RaCe instruments were allocated to group A, non-electropolished RaCe instruments to group B, and physical vapor deposition (PVD)-coated Alpha files to group C (10 instruments per group). Electrochemical measurements were carried out by using a potentiostat for galvanic current measurements. On the basis of electrochemical tests, no localized corrosion problems are to be expected in EDTA. In NaCl, pitting potential occurred at higher values for the electropolished and PVD instruments, indicating an increased corrosion resistance. There appears to be a risk of corrosion for NiTi instruments without surface treatments in contact with NaCl. NiTi files with PVD and electropolishing surface treatments showed an increase corrosion resistance.

  14. Inhibition of Staphylococcus aureus biofilm by a copper-bearing 317L-Cu stainless steel and its corrosion resistance.

    PubMed

    Sun, Da; Xu, Dake; Yang, Chunguang; Chen, Jia; Shahzad, M Babar; Sun, Ziqing; Zhao, Jinlong; Gu, Tingyue; Yang, Ke; Wang, Guixue

    2016-12-01

    The present study investigated the antibacterial performance, corrosion resistance and surface properties of antibacterial austenitic 317L-Cu stainless steel (317L-Cu SS). After 4.5wt% copper was added to 317L stainless steel (317L SS), the new alloy underwent solid solution and aging heat treatment. Fluorescent staining using 4',6-diamidino-2-phenylindole (DAPI) revealed that the 317L-Cu SS showed strong antibacterial efficacy, achieving a 99% inhibition rate of sessile Staphylococcus aureus cells after 5days. The corrosion data obtained by potentiodynamic polarization curves indicated that in comparison with 317L SS, the pitting potential and corrosion current density of 317L-Cu slightly decreased due to the addition of Cu. The 317L-Cu SS exhibited no cytotoxicity against zebrafish (Danio rerio) embryos. The experimental results in this study demonstrated that the new alloy has potential applications in medical and daily uses.

  15. Development of Advanced Corrosion-Resistant Fe-Cr-Ni Austenitic Stainless Steel Alloy with Improved High-Temperature Strength and Creep-Resistance

    SciTech Connect

    Maziasz, P.J.; Swindeman, R.W.

    2001-06-15

    In February of 1999, a Cooperative Research and Development Agreement (CRADA) was undertaken between Oak Ridge National Laboratory (ORNL) and Special Metals Corporation - Huntington Alloys (formerly INCO Alloys International, Inc.) to develop a modified wrought austenitic stainless alloy with considerably more strength and corrosion resistance than alloy 800H or 800HT, but with otherwise similar engineering and application characteristics. Alloy 800H and related alloys have extensive use in coal flue gas environments, as well as for tubing or structural components in chemical and petrochemical applications. The main concept of the project was make small, deliberate elemental microalloying additions to this Fe-based alloy to produce, with proper processing, fine stable carbide dispersions for enhanced high temperature creep-strength and rupture resistance, with similar or better oxidation/corrosion resistance. The project began with alloy 803, a Fe-25Cr-35NiTi,Nb alloy recently developed by INCO, as the base alloy for modification. Smaller commercial developmental alloy heats were produced by Special Metal. At the end of the project, three rounds of alloy development had produced a modified 803 alloy with significantly better creep resistance above 815 C (1500 C) than standard alloy 803 in the solution-annealed (SA) condition. The new upgraded 803 alloy also had the potential for a processing boost in that creep resistance for certain kinds of manufactured components that was not found in the standard alloy. The upgraded 803 alloy showed similar or slightly better oxidation and corrosion resistance relative to standard 803. Creep strength and oxidation/corrosion resistance of the upgraded 803 alloy were significantly better than found in alloy 800 H, as originally intended. The CRADA was terminated in February 2003. A contributing factor was Special Metals Corporation being in Chapter 11 Bankruptcy. Additional testing, further commercial scale-up, and any potential

  16. FY05 HPCRM Annual Report: High-Performance Corrosion-Resistant Iron-Based Amorphous Metal Coatings

    SciTech Connect

    Farmer, J; Choi, J; Haslam, J; Day, S; Yang, N; Headley, T; Lucadamo, G; Yio, J; Chames, J; Gardea, A; Clift, M; Blue, G; Peters, W; Rivard, J; Harper, D; Swank, D; Bayles, R; Lemieux, E; Brown, R; Wolejsza, T; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Lavernia, E; Schoenung, J; Ajdelsztajn, L; Dannenberg, J; Graeve, O; Lewandowski, J; Perepezko, J; Hildal, K; Kaufman, L; Boudreau, J

    2007-09-20

    New corrosion-resistant, iron-based amorphous metals have been identified from published data or developed through combinatorial synthesis, and tested to determine their relative corrosion resistance. Many of these materials can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in some very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Two Fe-based amorphous metal formulations have been found that appear to have corrosion resistance comparable to, or better than that of Ni-based Alloy C-22, based on breakdown potential and corrosion rate. Both Cr and Mo provide corrosion resistance, B enables glass formation, and Y lowers critical cooling rate (CCR). SAM1651 has yttrium added, and has a nominal critical cooling rate of only 80 Kelvin per second, while SAM2X7 (similar to SAM2X5) has no yttrium, and a relatively high critical cooling rate of 610 Kelvin per second. Both amorphous metal formulations have strengths and weaknesses. SAM1651 (yttrium added) has a low critical cooling rate (CCR), which enables it to be rendered as a completely amorphous thermal spray coating. Unfortunately, it is relatively difficult to atomize, with powders being irregular in shape. This causes the powder to be difficult to pneumatically convey during thermal spray deposition. Gas atomized SAM1651 powder has required cryogenic milling to eliminate irregularities that make flow difficult. SAM2X5 (no yttrium) has a high critical cooling rate, which has caused problems associated with devitrification. SAM2X5 can be gas atomized to produce spherical powders of SAM2X5, which enable more facile thermal spray deposition. The reference material, nickel-based Alloy C-22, is an outstanding corrosion-resistant engineering material. Even so, crevice corrosion has been observed with C-22 in hot sodium chloride environments without buffer

  17. Improving hot corrosion resistance of two phases intermetallic alloy α2-Ti3Al/γ-TiAl with enamel coating

    NASA Astrophysics Data System (ADS)

    Pambudi, Muhammad Jajar; Basuki, Eddy Agus; Prajitno, Djoko Hadi

    2017-01-01

    TiAl intermetallic alloys have attracted great interest among aerospace industry after successful utilization in low pressure turbine blades of aircraft engine which makes dramatic weight saving up to 40% weight saving. However, poor oxidation and corrosion resistance at temperatures above 800°C still become the drawbacks of this alloys, making the development of protective coatings to improve the resistance is important. This study investigates the hot corrosion behavior of two phases intermetallic alloy α2-Ti3Al/γ-TiAl with and without enamel coating using immersion test method in molten salt of 85%-wt Na2SO4 and 15%-wt NaCl at 850°C. The results show after 50 hours of hot corrosion test, bare alloy showed poor hot corrosion resistance due to the formation of non-protective Al2O3+TiO2 mixed scale at the surface of the alloy. Improvement of hot corrosion resistance was obtained in samples protected with enamel coating, indicated by significant decreasing in mass change (mg/cm2) by 98.20%. Enamel coating is expected to has the capability in suppressing the diffusion of oxygen and corrosive ions into the substrate layer, and consequently, it improves hot corrosion resistance of the alloy. The study showed that enamel coatings have strong adherent to the substrate and no spallation was observed after hot corrosion test. Nevertheless, the dissolution of oxides components of the enamel coating into the molten salts was observed that lead enamel coating degradation. This degradation is believed involving Cl- anion penetration into the substrate through voids in the coating that accelerates the corrosion of the two phases α2-Ti3Al/γ-TiAl alloy. Even though further observations are needed, it appears that enamel coating could be a promising protective coating to increase hot corrosion resistance of TiAl intermetallic alloys.

  18. Improved Corrosion Resistance of As-Extruded GZ51K Biomagnesium Alloy with High Mechanical Properties by Aging Treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaobo; Wang, Qian; Ba, Zhixin; Wang, Zhangzhong; Xue, Yajun

    2016-03-01

    Effects of aging treatment on microstructure, mechanical properties, and corrosion behavior of the as-extruded Mg-5Gd-1Zn-0.6Zr (GZ51K, wt.%) alloy were investigated. Microstructure was observed by optical microscopy and scanning electron microscopy, mechanical properties were tested on a tensile test machine and a microhardness tester, and corrosion behavior was evaluated by mass loss and polarization tests. It is found that most of equiaxed α-Mg grains have long-period stacking ordered (LPSO) structure, and some of them have no LPSO structure. Long-elongated grains are formed in the as-extruded alloy due to partial recrystallization and disappear after being aged at 200 and 220 °C. The as-extruded alloy exhibits both high-yield strength and high ductility. The mechanical properties of the alloy are not apparently enhanced, but the corrosion resistance is significantly improved after aging treatment. Moreover, the alloy with LPSO structure presents uniform corrosion mode in simulated body fluid. The GZ51K alloy with high mechanical properties and uniform corrosion behavior is worthy to be further investigated for biomedical applications.

  19. Electrochemical studies on the stability and corrosion resistance of titanium-based implant materials.

    PubMed

    Aziz-Kerrzo, M; Conroy, K G; Fenelon, A M; Farrell, S T; Breslin, C B

    2001-06-01

    The corrosion susceptibility of Ti, Ti-6A1-4V and Ti-45Ni was studied in a buffered saline solution using anodic polarisation and electrochemical impedance measurements. Pitting potentials as low as + 250 mV(SCE) were recorded for Ti-45Ni and once initiated pits continued to propagate at potentials as low as -150 mV(SCE). It was possible to increase the pitting potential of Ti-45Ni to values greater than +800 mV(SCE) using a H2O2 surface treatment procedure; however, this surface modification process had no beneficial effect on the rate of pit repassivation. Impedance spectra, recorded under open-circuit conditions, were modelled using a dual oxide film model; a porous outer layer and an inner barrier oxide layer. The nature of this porous outer layer was found to depend on the nature of the electrode material and the presence of phosphate anions in the saline-buffered solution. The porous layers formed on Ti-45Ni and Ti-6Al-4V in the presence of phosphate anions had low resistances typically between 10 and 70 ohm cm2. Much higher porous layer resistances were recorded for Ti and also for Ti-45Ni and Ti-6Al-4V in the absence of the phosphate anions.

  20. Preparation of the Multi-Walled Carbon Nanotubes/Nickel Composite Coating with Superior Wear and Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Li, Xuewu; Gu, Yang; Shi, Tian; Peng, Dai; Tang, Mingkai; Zhang, Qiaoxin; Huang, Xingjiu

    2015-12-01

    The multi-walled carbon nanotubes/nickel (MWCNTs/Ni) nanocomposite coatings were prepared on Cu substrate by electro-deposition method in the electrolyte with well-dispersed MWCNTs. Surface morphologies of the composite coatings with protrusion structures were confirmed by scanning electron microscopy. X-ray diffraction, fourier transform infrared spectroscopy, and energy-dispersive x-ray spectrometer were used to characterize the phase structures, functional groups, and elements distribution of the coatings as well as the incorporated MWCNTs. In addition, the effect of MWCNTs percentage on thickness, hardness, wear, and corrosion resistance of the coatings was also investigated. Results indicated that the incorporation of MWCNTs positively affected the hardness of coatings for their strengthening skeletons effect. Meanwhile, the coating with the MWCNTs concentration of 0.2 g/L could achieve the lowest friction coefficient, wear rate as well as the mass loss in the tribological test by a ball-on-disk tribometer. And also, the optimal corrosion resistance with the highest corrosion potential ( E corr) and the lowest corrosion current density ( I corr) of the composite coating was finally proved after the potentiodynamic polarization evaluation, which could promote the potential applications in preparing the functional nanocomposite materials.