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Sample records for heat resistant austenitic

  1. Effect of heat input on the microstructure, residual stresses and corrosion resistance of 304L austenitic stainless steel weldments

    SciTech Connect

    Unnikrishnan, Rahul; Idury, K.S.N. Satish; Ismail, T.P.; Bhadauria, Alok; Shekhawat, S.K.; Khatirkar, Rajesh K.; Sapate, Sanjay G.

    2014-07-01

    Austenitic stainless steels are widely used in high performance pressure vessels, nuclear, chemical, process and medical industry due to their very good corrosion resistance and superior mechanical properties. However, austenitic stainless steels are prone to sensitization when subjected to higher temperatures (673 K to 1173 K) during the manufacturing process (e.g. welding) and/or certain applications (e.g. pressure vessels). During sensitization, chromium in the matrix precipitates out as carbides and intermetallic compounds (sigma, chi and Laves phases) decreasing the corrosion resistance and mechanical properties. In the present investigation, 304L austenitic stainless steel was subjected to different heat inputs by shielded metal arc welding process using a standard 308L electrode. The microstructural developments were characterized by using optical microscopy and electron backscattered diffraction, while the residual stresses were measured by X-ray diffraction using the sin{sup 2}ψ method. It was observed that even at the highest heat input, shielded metal arc welding process does not result in significant precipitation of carbides or intermetallic phases. The ferrite content and grain size increased with increase in heat input. The grain size variation in the fusion zone/heat affected zone was not effectively captured by optical microscopy. This study shows that electron backscattered diffraction is necessary to bring out changes in the grain size quantitatively in the fusion zone/heat affected zone as it can consider twin boundaries as a part of grain in the calculation of grain size. The residual stresses were compressive in nature for the lowest heat input, while they were tensile at the highest heat input near the weld bead. The significant feature of the welded region and the base metal was the presence of a very strong texture. The texture in the heat affected zone was almost random. - Highlights: • Effect of heat input on microstructure, residual

  2. Cast, heat-resistant austenitic stainless steels having reduced alloying element content

    DOEpatents

    Muralidharan, Govindarajan [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Pankiw, Roman I [Greensburg, PA

    2011-08-23

    A cast, austenitic steel composed essentially of, expressed in weight percent of the total composition, about 0.4 to about 0.7 C, about 20 to about 30 Cr, about 20 to about 30 Ni, about 0.5 to about 1 Mn, about 0.6 to about 2 Si, about 0.05 to about 1 Nb, about 0.05 to about 1 W, about 0.05 to about 1.0 Mo, balance Fe, the steel being essentially free of Ti and Co, the steel characterized by at least one microstructural component selected from the group consisting of MC, M.sub.23C.sub.6, and M(C, N).

  3. Cast, heat-resistant austenitic stainless steels having reduced alloying element content

    DOEpatents

    Muralidharan, Govindarajan [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Pankiw, Roman I [Greensburg, PA

    2010-07-06

    A cast, austenitic steel composed essentially of, expressed in weight percent of the total composition, about 0.4 to about 0.7 C, about 20 to about 30 Cr, about 20 to about 30 Ni, about 0.5 to about 1 Mn, about 0.6 to about 2 Si, about 0.05 to about 1 Nb, about 0.05 to about 1 W, about 0.05 to about 1.0 Mo, balance Fe, the steel being essentially free of Ti and Co, the steel characterized by at least one microstructural component selected from the group consisting of MC, M.sub.23C.sub.6, and M(C, N).

  4. Creep Behavior at 1273 K (1000 °C) in Nb-Bearing Austenitic Heat-Resistant Cast Steels Developed for Exhaust Component Applications

    NASA Astrophysics Data System (ADS)

    Zhang, Yinhui; Li, Mei; Godlewski, Larry A.; Zindel, Jacob W.; Feng, Qiang

    2016-05-01

    ABSTRACT A series of Nb-bearing austenitic heat-resistant cast steels with variations of N/C ratios were investigated, and the morphological change of Nb(C,N) from faceted blocks, mixed flake-blocks to "Chinese-script" was observed as N/C ratios decreased. The creep behavior of these alloys was studied at 1273 K (1000 °C), and the longest creep life and lowest creep rate occurred in model alloys with script Nb(C,N). Residual δ-ferrites and (Cr,Fe)23C6 were adverse to creep properties. This work indicates that the control of N/C ratio is required for the as-cast microstructural strengthening.

  5. Creep Behavior at 1273 K (1000 °C) in Nb-Bearing Austenitic Heat-Resistant Cast Steels Developed for Exhaust Component Applications

    NASA Astrophysics Data System (ADS)

    Zhang, Yinhui; Li, Mei; Godlewski, Larry A.; Zindel, Jacob W.; Feng, Qiang

    2016-07-01

    A series of Nb-bearing austenitic heat-resistant cast steels with variations of N/C ratios were investigated, and the morphological change of Nb(C,N) from faceted blocks, mixed flake-blocks to "Chinese-script" was observed as N/C ratios decreased. The creep behavior of these alloys was studied at 1273 K (1000 °C), and the longest creep life and lowest creep rate occurred in model alloys with script Nb(C,N). Residual δ-ferrites and (Cr,Fe)23C6 were adverse to creep properties. This work indicates that the control of N/C ratio is required for the as-cast microstructural strengthening.

  6. 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.

  7. 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.

  8. The Effect of Nb and Ti on Structure and Mechanical Properties of 12Ni-25Cr-0.4C Austenitic Heat-Resistant Steel after Aging at 900 °C for 1000 h

    NASA Astrophysics Data System (ADS)

    Javaheri, Vahid; Shahri, Farzad; Mohammadnezhad, Mahyar; Tamizifar, Morteza; Naseri, Masaab

    2014-10-01

    Austenitic heat-resistant steels are particularly suitable for applications where service conditions comprise high temperature. The demand for better performance has motivated developments in these steels. In this work, Ti and Nb were added to austenitic heat-resistant steels, Fe-12Ni-25Cr-0.4C, wt.% simultaneously. Microstructural changes were studied via scanning electron microscopy equipped with energy dispersive spectrum (EDS), optical microscopy, and x-ray diffraction (XRD) in as-cast condition and after aging in 900 °C for 1000 h. Mechanical properties were measured using tensile tests, impact energy, and Vickers hardness. It was observed that by formation of NbC and TiC, the level of fragmentation of the chromium carbides increased, as a positive aspect for mechanical properties. XRD and EDS results show increasing the amount of Ti can inhibit G-phase transformation.

  9. 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.

  10. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, Philip J.; Braski, David N.; Rowcliffe, Arthur F.

    1989-01-01

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01% to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties.

  11. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, P.J.; Braski, D.N.; Rowcliffe, A.F.

    1987-02-11

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01 to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties. 4 figs.

  12. Improved high temperature creep resistant austenitic alloy

    DOEpatents

    Maziasz, P.J.; Swindeman, R.W.; Goodwin, G.M.

    1988-05-13

    An improved austenitic alloy having in wt% 19-21 Cr, 30-35 Ni, 1.5-2.5 Mn, 2-3 Mo, 0.1-0.4 Si, 0.3-0.5 Ti, 0.1-0.3 Nb, 0.1-0.5 V, 0.001-0.005 P, 0.08-0.12 C, 0.01-0.03 N, 0.005-0.01 B and the balance iron that is further improved by annealing for up to 1 hour at 1150-1200/degree/C and then cold deforming 5-15%. The alloy exhibits dramatically improved creep rupture resistance and ductility at 700/degree/C. 2 figs.

  13. High temperature creep resistant austenitic alloy

    DOEpatents

    Maziasz, Philip J.; Swindeman, Robert W.; Goodwin, Gene M.

    1989-01-01

    An improved austenitic alloy having in wt % 19-21 Cr, 30-35 Ni, 1.5-2.5 Mn, 2-3 Mo, 0.1-0.4 Si, 0.3-0.5 Ti, 0.1-0.3 Nb, 0.1-0.5 V, 0.001-0.005 P, 0.08-0.12 C, 0.01-0.03 N, 0.005-0.01 B and the balance iron that is further improved by annealing for up to 1 hour at 1150.degree.-1200.degree. C. and then cold deforming 5-15 %. The alloy exhibits dramatically improved creep rupture resistance and ductility at 700.degree. C.

  14. Cast heat-resistant austenitic steel with improved temperature creep properties and balanced alloying element additions and methodology for development of the same

    DOEpatents

    Pankiw, Roman I; Muralidharan, Govindrarajan; Sikka, Vinod Kumar; Maziasz, Philip J

    2012-11-27

    The present invention addresses the need for new austenitic steel compositions with higher creep strength and higher upper temperatures. The new austenitic steel compositions retain desirable phases, such as austenite, M.sub.23C.sub.6, and MC in its microstructure to higher temperatures. The present invention also discloses a methodology for the development of new austenitic steel compositions with higher creep strength and higher upper temperatures.

  15. Oxidation resistant high creep strength austenitic stainless steel

    DOEpatents

    Brady, Michael P.; Pint, Bruce A.; Liu, Chain-Tsuan; Maziasz, Philip J.; Yamamoto, Yukinori; Lu, Zhao P.

    2010-06-29

    An austenitic stainless steel displaying high temperature oxidation and creep resistance has a composition that includes in weight percent 15 to 21 Ni, 10 to 15 Cr, 2 to 3.5 Al, 0.1 to 1 Nb, and 0.05 to 0.15 C, and that is free of or has very low levels of N, Ti and V. The alloy forms an external continuous alumina protective scale to provide a high oxidation resistance at temperatures of 700 to 800.degree. C. and forms NbC nanocarbides and a stable essentially single phase fcc austenitic matrix microstructure to give high strength and high creep resistance at these temperatures.

  16. Influence of retained austenite on short fatigue crack growth and wear resistance of case carburized steel

    SciTech Connect

    Silva, V.F. da; Canale, L.F.; Spinelli, D.P.; Bose-Filho, W.W.; Crnkovic, O.R.

    1999-10-01

    The influence of the amount of retained austenite on short fatigue crack growth and wear resistance in carburized SAE 8620 steel was studied in this article. Different amounts of retained austenite in the microstructure of the carburized case were obtained through different heat treatment routes applied after the carburizing process. The wear tests were carried out using pin on disk equipment. After every 200 turns the weight loss was registered. Four point bend fatigue tests were carried out at room temperature, using three different levels of stress and R = 0.1. Crack length versus number of cycles and crack growth rate versus mean crack length curves were analyzed. In both tests the results showed that the test pieces with higher levels of retained austenite in the carburized case exhibited longer fatigue life and better wear resistance.

  17. Evolution of Precipitate Phases During Long-Term Isothermal Aging at 1083 K (810 °C) in a New Precipitation-Strengthened Heat-Resistant Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Ha, Vu The; Jung, Woo Sang

    2012-09-01

    Evolution of precipitate phases in a precipitation-strengthened high nitrogen 15Cr-15Ni-4Mn-3Cu-1.5Mo-0.46Si-Nb-C-N-Al-B austenitic heat-resistant stainless steel during 10,000 hours of isothermal aging at 1083 K (810 °C) was investigated. The major precipitate phases found in microstructure after 330 hours of aging are coarser residual primary Nb(C,N) precipitates, Z-phase precipitates, (Nb,Cr)N precipitates with fcc crystal structure, Cu precipitates, and coarser Cr2N precipitates. No significant changes were noted in the chemical compositions, crystal structure of the precipitate phases, or the phase species after 10,000 hours at 1083 K (810 °C). The coarsening behavior of Z-phase, (Nb,Cr)N, and Cu precipitates was the only observed notable change in the microstructures during the performed aging. Z-phase and (Nb,Cr)N precipitates exhibited superior dimensional stability and morphology with extremely low coarsening rates, while Cu precipitates coarsened at the fastest rate. In addition, Z-phase particles showed a remarkable lower coarsening rate as compared to that of (Nb,Cr)N precipitates. The abnormal slow coarsening kinetics of Z-phase can be explained by the nucleation energy barrier (NEB) limited coarsening mechanism applied for faceted ceramic crystals.

  18. 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.

  19. Weldability of corrosion-resistant high-nitrogen austenitic Kh22AG16N8M-type steels

    NASA Astrophysics Data System (ADS)

    Bannykh, O. A.; Blinov, V. M.; Kostina, M. V.; Blinov, E. V.; Zvereva, T. N.

    2007-10-01

    The influence of thermal treatment on the structures and mechanical properties of welds of corrosion-resistant high-nitrogen austenitic 05Kh22AG16N8M-type steels is studied. In these steels, austenite is found to be highly resistant to discontinuous precipitation and the formation of σ phase and δ ferrite upon cooling regardless of the temperature of heating for quenching (from 900 to 1250°C) and the cooling conditions (water, air, furnace). Welding of these steels can produce high-strength welds with an enhanced impact toughness.

  20. Heat treatment giving a stable high temperature micro-structure in cast austenitic stainless steel

    DOEpatents

    Anton, Donald L.; Lemkey, Franklin D.

    1988-01-01

    A novel micro-structure developed in a cast austenitic stainless steel alloy and a heat treatment thereof are disclosed. The alloy is based on a multicomponent Fe-Cr-Mn-Mo-Si-Nb-C system consisting of an austenitic iron solid solution (.gamma.) matrix reinforced by finely dispersed carbide phases and a heat treatment to produce the micro-structure. The heat treatment includes a prebraze heat treatment followed by a three stage braze cycle heat treatment.

  1. Austenite Formation Kinetics During Rapid Heating in a Microalloyed Steel

    SciTech Connect

    BURNETT,M.E.; DYKHUIZEN,RONALD C.; KELLEY,J. BRUCE; PUSKAR,JOSEPH D.; ROBINO,CHARLES V.

    1999-09-07

    The model parameters for the normalized 1054V1 material were compared to parameters previously generated for 1026 steel, and the transformation behavior was relatively consistent. Validation of the model predictions by heating into the austenite plus undissolved ferrite phase field and rapidly quenching resulted in reasonable predictions when compared to the measured volume fractions from optical metallography. The hot rolled 1054V1 material, which had a much coarser grain size and a non-equilibrium volume fraction of pearlite, had significantly different model parameters and the on heating transformation behavior of this material was less predictable with the established model. The differences in behavior is consistent with conventional wisdom that normalized micro-structure produce a more consistent response to processing, and it reinforces the need for additional work in this area.

  2. Effect of material heat treatment on fatigue crack initiation in austenitic stainless steels in LWR environments.

    SciTech Connect

    Chopra, O. K.; Alexandreanu, B.; Shack, W. J.; Energy Technology

    2005-07-31

    The ASME Boiler and Pressure Vessel Code provides rules for the design of Class 1 components of nuclear power plants. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify design curves for applicable structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. The existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. Under certain environmental and loading conditions, fatigue lives of austenitic stainless steels (SSs) can be a factor of 20 lower in water than in air. This report presents experimental data on the effect of heat treatment on fatigue crack initiation in austenitic Type 304 SS in LWR coolant environments. A detailed metallographic examination of fatigue test specimens was performed to characterize the crack morphology and fracture morphology. The key material, loading, and environmental parameters and their effect on the fatigue life of these steels are also described. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic SSs as a function of material, loading, and environmental parameters. Two methods for incorporating the effects of LWR coolant environments into the ASME Code fatigue evaluations are presented.

  3. Enhancing Hydrogen Embrittlement Resistance of Lath Martensite by Introducing Nano-Films of Interlath Austenite

    NASA Astrophysics Data System (ADS)

    Wang, Meimei; Tasan, C. Cem; Koyama, Motomichi; Ponge, Dirk; Raabe, Dierk

    2015-09-01

    Partial reversion of interlath austenite nano-films is investigated as a potential remedy for hydrogen embrittlement susceptibility of martensitic steels. We conducted uniaxial tensile tests on hydrogen-free and pre-charged medium-Mn transformation-induced plasticity-maraging steels with different austenite film thicknesses. Mechanisms of crack propagation and microstructure interaction are quantitatively analyzed using electron channelling contrast imaging and electron backscatter diffraction, revealing a promising strategy to utilize austenite reversion for hydrogen-resistant martensitic steel design.

  4. Abrasion resistant heat pipe

    DOEpatents

    Ernst, Donald M.

    1984-10-23

    A specially constructed heat pipe for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

  5. Abrasion resistant heat pipe

    DOEpatents

    Ernst, D.M.

    1984-10-23

    A specially constructed heat pipe is described for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

  6. The effect of heat treatment on the gouging abrasion resistance of alloy white cast irons

    NASA Astrophysics Data System (ADS)

    Are, I. R. S.; Arnold, B. K.

    1995-02-01

    A series of heat treatments was employed to vary the microstructure of four commercially important alloy white cast irons, the wear resistance of which was then assessed by the ASTM jaw-crusher gouging abrasion test. Compared with the as-cast condition, standard austenitizing treatments produced a substantial increase in hardness, a marked decrease in the retained aus-tenite content in the matrix, and, in general, a significant improvement in gouging abrasion resistance. The gouging abrasion resistance tended to decline with increasing austenitizing tem-perature, although the changes in hardness and retained austenite content varied, depending on alloy composition. Subcritical heat treatment at 500 ° following hardening reduced the retained austenite content to values less than 10 pct, and in three of the alloys it caused a significant fall in both hardness and gouging abrasion resistance. The net result of the heat treatments was the development of optimal gouging abrasion resistance at intermediate levels of retained aus-tenite. The differing responses of the alloys to both high-temperature austenitizing treatments and to subcritical heat treatments at 500 ° were related to the effects of the differing carbon and alloying-element concentrations on changes in the M s temperature and secondary carbide precipitation.

  7. Corrosion behavior in high heat input welded heat-affected zone of Ni-free high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel

    SciTech Connect

    Moon, Joonoh Ha, Heon-Young; Lee, Tae-Ho

    2013-08-15

    The pitting corrosion and interphase corrosion behaviors in high heat input welded heat-affected zone (HAZ) of a metastable high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel were explored through electrochemical tests. The HAZs were simulated using Gleeble simulator with high heat input welding condition of 300 kJ/cm and the peak temperature of the HAZs was changed from 1200 °C to 1350 °C, aiming to examine the effect of δ-ferrite formation on corrosion behavior. The electrochemical test results show that both pitting corrosion resistance and interphase corrosion resistance were seriously deteriorated by δ-ferrite formation in the HAZ and their aspects were different with increasing δ-ferrite fraction. The pitting corrosion resistance was decreased by the formation of Cr-depleted zone along δ-ferrite/austenite (γ) interphase resulting from δ-ferrite formation; however it didn't depend on δ-ferrite fraction. The interphase corrosion resistance depends on the total amount of Cr-depleted zone as well as ferrite area and thus continuously decreased with increasing δ-ferrite fraction. The different effects of δ-ferrite fraction on pitting corrosion and interphase corrosion were carefully discussed in terms of alloying elements partitioning in the HAZ based on thermodynamic consideration. - Highlights: • Corrosion behavior in the weld HAZ of high-nitrogen austenitic alloy was studied. • Cr{sub 2}N particle was not precipitated in high heat input welded HAZ of tested alloy. • Pitting corrosion and interphase corrosion show a different behavior. • Pitting corrosion resistance was affected by whether or not δ-ferrite forms. • Interphase corrosion resistance was affected by the total amount of δ-ferrite.

  8. Retained Austenite in SAE 52100 Steel Post Magnetic Processing and Heat Treatment

    SciTech Connect

    Pappas, Nathaniel R; Watkins, Thomas R; Cavin, Odis Burl; Jaramillo, Roger A; Ludtka, Gerard Michael

    2007-01-01

    Steel is an iron-carbon alloy that contains up to 2% carbon by weight. Understanding which phases of iron and carbon form as a function of temperature and percent carbon is important in order to process/manufacture steel with desired properties. Austenite is the face center cubic (fcc) phase of iron that exists between 912 and 1394 C. When hot steel is rapidly quenched in a medium (typically oil or water), austenite transforms into martensite. The goal of the study is to determine the effect of applying a magnetic field on the amount of retained austenite present at room temperature after quenching. Samples of SAE 52100 steel were heat treated then subjected to a magnetic field of varying strength and time, while samples of SAE 1045 steel were heat treated then subjected to a magnetic field of varying strength for a fixed time while being tempered. X-ray diffraction was used to collect quantitative data corresponding to the amount of each phase present post processing. The percentage of retained austenite was then calculated using the American Society of Testing and Materials standard for determining the amount of retained austenite for randomly oriented samples and was plotted as a function of magnetic field intensity, magnetic field apply time, and magnetic field wait time after quenching to determine what relationships exist with the amount of retained austenite present. In the SAE 52100 steel samples, stronger field strengths resulted in lower percentages of retained austenite for fixed apply times. The results were inconclusive when applying a fixed magnetic field strength for varying amounts of time. When applying a magnetic field after waiting a specific amount of time after quenching, the analyses indicate that shorter wait times result in less retained austenite. The SAE 1045 results were inconclusive. The samples showed no retained austenite regardless of magnetic field strength, indicating that tempering removed the retained austenite. It is apparent

  9. Kinetic study of austenite formation during continuous heating of unalloyed ductile iron

    NASA Astrophysics Data System (ADS)

    Vázquez-Gómez, Octavio; Barrera-Godínez, José Antonio; Vergara-Hernández, Héctor Javier

    2015-01-01

    The austenite formation kinetics in unalloyed cast ductile iron was studied on the basis of dilatometry measurements, and Avrami's equation was used to estimate the material's kinetic parameters. A continuous heating transformation diagram was constructed using heating rates in the range of 0.06 to 0.83°C·s-1. As the heating rate was augmented, the critical temperatures, A c1 and A α, as well as the intercritical range, which was evaluated as the difference between the critical temperatures, Δ T = A α - A c1, increased. At a low heating rate, the kinetics of austenite formation was slow as a consequence of the iron's silicon content. The effect of heating rate on k and n, the kinetic parameters of Avrami's equation, was also determined. Parameter n, which is associated with nucleation sites and growth geometry, decreased with an increase in heating rate. In addition, parameter k increased with the increase of heating rate, suggesting that the nucleation and growth rates are carbon- and silicon-diffusion controlled during austenite formation under continuous heating.

  10. Copper modified austenitic stainless steel alloys with improved high temperature creep resistance

    DOEpatents

    Swindeman, R.W.; Maziasz, P.J.

    1987-04-28

    An improved austenitic stainless steel that incorporates copper into a base Fe-Ni-Cr alloy having minor alloying substituents of Mo, Mn, Si, T, Nb, V, C, N, P, B which exhibits significant improvement in high temperature creep resistance over previous steels. 3 figs.

  11. 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.

  12. 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.

  13. Modeling the Ferrite-Austenite Transformation in the Heat-Affected Zone of Stainless Steel Welds

    SciTech Connect

    Vitek, J.M.; David, S.A.

    1997-12-01

    The diffusion-controlled ferrite-austenite transformation in stainless steel welds was modeled. An implicit finite-difference analysis that considers multi-component diffusion was used. The model was applied to the Fe-Cr-Ni system to investigate the ferrite- austenite transformation in the heat-affected zone of stainless steel weld metal. The transformation was followed as a function of time as the heat-affected zone was subjected to thermal cycles comparable to those experienced during gas-tungsten arc welding. The results showed that the transformation behavior and the final microstructural state are very sensitive to the maximum temperature that is experienced by the heat-affected zone. For high maximum exposure temperatures ({approximately} 1300{degree} C), the ferrite formation that occurs at the highest temperatures is not completely offset by the reverse ferrite dissolution at lower temperatures. As a result, for high temperature exposures there is a net increase in the amount of ferrite in the microstructure. It was also found that if compositional gradients are present in the initial ferrite and austenite phases, the extent of the transformation is impacted.

  14. Iron aluminide useful as electrical resistance heating elements

    SciTech Connect

    Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

    1999-11-02

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {le}1% Cr and either {ge}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {ge}0.1% oxide dispersoid particles. The alloy can contain 14--32% Al, {le}2% Ti, {le}2% Mo, {le}1% Zr, {le}1% C, {le}0.1% B, {le}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {le}1% rare earth metal, {le}1% oxygen, {le}3% Cu, balance Fe.

  15. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    2001-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  16. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    1997-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  17. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

    1997-04-15

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {<=}1% Cr and either {>=}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {>=}0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, {<=}2% Ti, {<=}2% Mo, {<=}1% Zr, {<=}1% C, {<=}0.1% B, {<=}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, {<=}1% oxygen, {<=}3% Cu, balance Fe. 64 figs.

  18. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    1999-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  19. Heat resistant protective hand covering

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R.; Arons, I. J. (Inventor)

    1984-01-01

    A heat-resistant aromatic polyamide fiber is described. The outer surface of the shell is coated with a fire-resistant elastomer and liner. Generally conforming and secured to the shell and disposed inwardly of the shell, the liner is made of a felt fabric of temperature-resistant aromatic polymide fiber.

  20. The Effects of Austenitizing Conditions on the Microstructure and Wear Resistance of a Centrifugally Cast High-Speed Steel Roll

    NASA Astrophysics Data System (ADS)

    Kang, Minwoo; Lee, Young-Kook

    2016-04-01

    The influences of austenitizing conditions on the microstructure and wear resistance of a centrifugally cast high-speed steel roll were investigated through thermodynamic calculation, microstructural analysis, and high-temperature wear tests. When the austenitizing temperature was between 1323 K and 1423 K (1050 °C and 1150 °C), coarse eutectic M2C plates were decomposed into a mixture of MC and M6C particles. However, at 1473 K (1200 °C), the M2C plates were first replaced by both new austenite grains and MC particles without M6C particles, and then remaining M2C particles were dissolved during the growth of MC particles. The wear resistance of the HSS roll was improved with increasing austenitizing temperature up to 1473 K (1200 °C) because the coarse eutectic M2C plates, which are vulnerable to crack propagation, changed to disconnected hard M6C and MC particles.

  1. The Effects of Austenitizing Conditions on the Microstructure and Wear Resistance of a Centrifugally Cast High-Speed Steel Roll

    NASA Astrophysics Data System (ADS)

    Kang, Minwoo; Lee, Young-Kook

    2016-07-01

    The influences of austenitizing conditions on the microstructure and wear resistance of a centrifugally cast high-speed steel roll were investigated through thermodynamic calculation, microstructural analysis, and high-temperature wear tests. When the austenitizing temperature was between 1323 K and 1423 K (1050 °C and 1150 °C), coarse eutectic M2C plates were decomposed into a mixture of MC and M6C particles. However, at 1473 K (1200 °C), the M2C plates were first replaced by both new austenite grains and MC particles without M6C particles, and then remaining M2C particles were dissolved during the growth of MC particles. The wear resistance of the HSS roll was improved with increasing austenitizing temperature up to 1473 K (1200 °C) because the coarse eutectic M2C plates, which are vulnerable to crack propagation, changed to disconnected hard M6C and MC particles.

  2. Kinetics of Austenite Grain Growth During Heating and Its Influence on Hot Deformation of LZ50 Steel

    NASA Astrophysics Data System (ADS)

    Du, Shiwen; Li, Yongtang; Zheng, Yi

    2016-07-01

    Grain growth behaviors of LZ50 have been systematically investigated for various temperatures and holding times. Quantitative evaluations of the grain growth kinetics over a wide range of temperature (950-1200 °C) and holding time (10-180 min) have been performed. With the holding time kept constant, the average austenite grain size has an exponential relationship with the heating temperature, while with the heating temperature kept constant, the relationship between the austenite average grain size and holding time is a parabolic curve approximately. The holding time dependence of average austenite grain size obeys the Beck's equation. As the heating temperature increases, the time exponent for grain growth n increases from 0.21 to 0.39. On the basis of previous models and experimental results, taking the initial grain size into account, the mathematical model for austenite grain growth of LZ50 during isothermal heating and non-isothermal heating is proposed. The effects of initial austenite grain size on hot deformation behavior of LZ50 are analyzed through true stress-strain curves under different deformation conditions. Initial grain size has a slight effect on peak stress.

  3. Heat resistant polyphosphazene polymers

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Allcock, H. R.; Obrien, J. P.; Scopelianos, A. G.

    1981-01-01

    Polymers of carboranyl substituted polyphosphazene are stable at high temperatures and produce insulating char upon pyrolysis. Substituted compounds are prepared by heat polymerizing carboranyl halophosphazene, which is obtained by reacting lithium carborane with, for example, hexachlorocyclotriphosphazene under anhydrous conditions. Chlorine of polymer may be replaced by aryloxy and alkoxy groups.

  4. Swelling and swelling resistance possibilities of austenitic stainless steels in fusion reactors

    SciTech Connect

    Maziasz, P.J.

    1983-01-01

    Fusion reactor helium generation rates in stainless steels are intermediate to those found in EBR-II and HFIR, and swelling in fusion reactors may differ from the fission swelling behavior. Advanced titanium-modified austenitic stainless steels exhibit much better void swelling resistance than AISI 316 under EBR-II (up to approx. 120 dpa) and HFIR (up to approx. 44 dpa) irradiations. The stability of fine titanium carbide (MC) precipitates plays an important role in void swelling resistance for the cold-worked titanium-modified steels irradiated in EBR-II. Futhermore, increased helium generation in these steels can (a) suppress void conversion, (b) suppress radiation-induced solute segregation (RIS), and (c) stabilize fine MC particles, if sufficient bubble nucleation occurs early in the irradation. The combined effects of helium-enhanced MC stability and helium-suppressed RIS suggest better void swelling resistance in these steels for fusion service than under EBR-II irradiation.

  5. Development of corrosion-resistant improved Al-doped austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Kondo, Keietsu; Miwa, Yukio; Okubo, Nariaki; Kaji, Yoshiyuki; Tsukada, Takashi

    2011-10-01

    Aluminum-doped type 316L SS (316L/Al) has been developed for the purpose of suppressing the degradation of corrosion resistance induced by irradiation in austenitic stainless steels (SSs). The electrochemical corrosion properties of this material were estimated after Ni-ion irradiation at a temperature range from 330 °C to 550 °C. When irradiated at 550 °C up to 12 dpa, 316L/Al showed high corrosion resistance in the vicinity of grain boundaries (GBs) and in grains, while severe GB etching and local corrosion in grains were observed in irradiated 316L and 316 SS. It is supposed that aluminum enrichment was enhanced by high-temperature irradiation at GBs and in grains, to compensate for lost corrosion resistance induced by chromium depletion.

  6. The Optimization and Design of a Fully Austenitic, Gamma-Prime Strengthened TRIP Steel for Blast and Fragment Resistance

    NASA Astrophysics Data System (ADS)

    Wengrenovich, Nicholas J.

    Current analysis into the property requirements of materials designed for blast and fragment protection has led to the need for high tensile uniform ductility to withstand the pressure wave and high shear localization resistance to withstand fragment penetration. Additionally, it has been shown that steels with retained austenite are able to outperform standard martensitic steels when subjected to fragment simulating projectiles (FSP) in ballistic experiments. Using a systems based, computational materials design approach, a series of prototype precipitation strengthened, fully austenitic steels have been designed to obtain superior performance in blast and fragment protection. The most recent design, TRIP-180, explores optimized transformation induced plasticity (TRIP) to counteract strain softening and thus significantly increase uniform plastic deformation in both tension and shear at high strength (1241 MPa / 180 ksi). The transformation hardening delays the onset of localization, which in tension delays necking, and in shear delays plugging. Through precipitation heat treatment, the matrix composition can be varied to optimize the austenite stability, quantified by the Ms sigma temperature. Baseline data quantifying the martensitic transformation in shear was obtained through a series of quasi-static torsion experiments performed on TRIP-180. Analysis of the postmortem microstructures allowed for calibration of M_s. sigma(sh) temperatures with the transformation product morphologiesin the stress-assisted regime, where the plate martensite forms at the same locations as when quenching, and strain-induced regime, where the finely dispersed martensite forms at the intersections of shear bands. Dynamic testing (E = 104/s) identified the optimal austenite stability ( T -- Ms sigma(sh) = 60°C ) required to delay the shear localization instability at higher ultimate shear stress levels (1420 MPa) and larger plastic strains (0.103) than an existing Navy standard

  7. Role of microstructure and heat treatments on the desorption kinetics of tritium from austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Chêne, J.; Brass, A.-M.; Trabuc, P.; Gastaldi, O.

    2007-02-01

    The liquid scintillation counting of solid samples (LSC-SS technique) was successfully used to study the role of microstructure and heat treatments on the behavior of residual tritium in several austenitic stainless steels (as-cast remelted tritiated waste, 316LN and 321 steels). The role of desorption annealing in the 100-600 °C range on the residual amount of tritium in tritiated waste was investigated. The residual tritium concentration computed from surface activity measurements is in good agreement with experimental values measured by liquid scintillation counting after full dissolution of the samples. The kinetics of tritium desorption recorded with the LSC-SS technique shows a significant desorption of residual tritium at room temperature, a strong barrier effect of thermal oxide films on the tritium desorption and a dependance of the tritium release on the steels microstructure. Annealing in the 300-600 °C range allows to desorb a large fraction of the residual tritium. However a significant trapping of tritium is evidenced. The influence of trapping phenomena on the concentration of residual tritium and on its dependance with the annealing temperature was investigated with different recrystallized and sensitized microstructures. Trapping is evidenced mainly below 150 °C and concerns a small fraction of the total amount of tritium introduced in austenitic steels. It presumably occurs preferentially on precipitates such as Ti(CN) or on intermetallic phases.

  8. Thermal embrittlement of simulated heat-affected zone in cast austenitic stainless steels

    SciTech Connect

    Mimura, H.; Taniguchi, T.; Horii, Y.; Kume, R.; Uesugi, N.

    1998-08-01

    Metallurgical factors controlling thermal embrittlement in the heat-affected zone (HAZ) of cast austenitic stainless steels were investigated by using the simulated HAZ. It was shown that the simulated HAZ was more susceptible to the thermal embrittlement by aging at 673 K in correspondence with its higher tendency to age hardening and a higher content of ferrite than the parent casting. Electron microprobe analyzer measurement showed that application of the simulated thermal cycle gave a change in the chemical composition of the ferrite, which might be a cause of the higher age hardening of the ferrite in the simulated HAZ. This higher ferrite hardness had a good correlation with fine precipitates of presumably G-phase in the ferrite grain, which existed more in the simulated HAZ than in the parent casting, though it is not clear whether this correlation was only apparent. Ductility of the austenite portion was found to reduce remarkably when surrounded by the hard ferrite of a high fraction. Annealing after aging restored CTOD to some degree. Aging after fatigue cracking gave more embrittlement than a usual procedure for preparation of test specimens, i.e., fatigue cracking after aging.

  9. Heat resistant protective hand covering

    NASA Technical Reports Server (NTRS)

    Sidman, K. R.; Arons, I. J. (Inventor)

    1984-01-01

    The heat resistant, protective glove is made up of first and second shell sections which define a palm side and a backside, respectively. The first shell section is made of a twill wave fabric of a temperature-resistant aromatic polyamide fiber. The second shell section is made of a knitted fabric of a temperature-resistant aromatic polyamide fiber. The first and second shell sections are secured to one another, e.g., by sewing, to provide the desired glove configuration and an opening for insertion of the wearer's hand. The protective glove also includes a first liner section which is secured to and overlies the inner surface of the first shell section and is made of a felt fabric of a temperature-resistant aromatic polyamide fiber and has a flame resistant, elastomenic coating on the surface facing and overlying the inner surface of the first shell section.

  10. On the decomposition of austenite in the heat-affected zone upon welding of high-strength steels

    NASA Astrophysics Data System (ADS)

    Efimenko, L. A.; Ramus', A. A.; Merkulova, A. O.

    2015-05-01

    The kinetics of the decomposition of austenite in the heat-affected zone of welded joints of low-carbon microalloyed high-strength steels has been investigated. A new approach to selecting the parameters of the thermal cycle of welding that ensure the service characteristics of welded joints on a level no lower than the normative requirements is suggested.

  11. Structure and composition of nanometer-sized nitrides in a creep resistant cast austenitic alloy

    SciTech Connect

    Evans, Neal D; Maziasz, Philip J; Shingledecker, John P.; Pollard, Michael J

    2010-01-01

    The microstructure of a new and improved high-temperature creep-resistant cast austenitic alloy, CF8C-Plus, was characterized after creep-rupture testing at 1023 K (750 C) and 100 MPa. Microstructures were investigated by detailed scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). Principal component analysis of EDS spectrum images was used to examine the complex precipitate morphology. Thermodynamic modeling was performed to predict equilibrium phases in this alloy as well as the compositions of these phases at relevant temperatures. The improved high-temperature creep strength of CF8C-Plus over its predecessor CF8C is suggested to be due to the modified microstructure and phase stability in the alloy, including the absence of {delta}-ferrite in the as-cast condition and the development of a stable, slow-growing precipitation hardening nitride phase - the tetragonal Z-phase - which has not been observed before in cast austenitic stainless steels.

  12. 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

  13. Turbulent resistivity, diffusion and heating

    NASA Technical Reports Server (NTRS)

    Fried, B. D.; Kennel, C. F.; Mackenzie, K.; Coroniti, F. V.; Kindel, J. M.; Stenzel, R.; Taylor, R. J.; White, R.; Wong, A. Y.; Bernstein, W.

    1971-01-01

    Experimental and theoretical studies are reported on ion acoustic and ion cyclotron turbulence and their roles in anomalous resistivity, viscosity, diffusion and heating and in the structure of collisionless electrostatic shocks. Resistance due to ion acoustic turbulence has been observed in experiments with a streaming cesium plasma in which electron current, potential rise due to turbulent resistivity, spectrum of unstable ion acoustic waves, and associated electron heating were all measured directly. Kinetic theory calculations for an expanding, unstable plasma, give results in agreement with the experiment. In a strong magnetic field, with T sub e/T sub i approximately 1 and current densities typical for present Tokomaks, the plasma is stable to ion acoustic but unstable to current driven electrostatic ion cyclotron waves. Relevant characteristics of these waves are calculated and it is shown that for ion, beta greater than m sub e/m sub i, the electromagnetic ion cyclotron wave has a lower instability threshold than the electrostatic one. However, when ion acoustic turbulence is present experiments with double plasma devices show rapid anomalous heating of an ion beam streaming through a plasma.

  14. Characterization of Low Temperature Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Arc Welds

    SciTech Connect

    Palmer, T A; Elmer, J W; Babu, S S; Vitek, J M

    2003-08-20

    Spatially Resolved X-Ray Diffraction (SRXRD) has been used to identify a previously unobserved low temperature ferrite ({delta})/austenite({gamma}) phase transformation in the heat affected zone (HAZ) of 2205 Duplex Stainless Steel (DSS) welds. In this ''ferrite dip'' transformation, the ferrite transforms to austenite during heating to peak temperatures on the order of 750 C, and re-transforms to ferrite during cooling, resulting in a ferrite volume fraction equivalent to that in the base metal. Time Resolved X-Ray Diffraction (TRXRD) and laser dilatometry measurements during Gleeble{reg_sign} thermal simulations are performed in order to verify the existence of this low temperature phase transformation. Thermodynamic and kinetic models for phase transformations, including both local-equilibrium and para-equilibrium diffusion controlled growth, show that diffusion of substitutional alloying elements does not provide a reasonable explanation for the experimental observations. On the other hand, the diffusion of interstitial alloying elements may be rapid enough to explain this behavior. Based on both the experimental and modeling results, two mechanisms for the ''ferrite dip'' transformation, including the formation and decomposition of secondary austenite and an athermal martensitic-type transformation of ferrite to austenite, are considered.

  15. 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

  16. Crack growth rates of irradiated austenitic stainless steel weld heat affected zone in BWR environments.

    SciTech Connect

    Chopra, O. K.; Alexandreanu, B.; Gruber, E. E.; Daum, R. S.; Shack, W. J.; Energy Technology

    2006-01-31

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of reactor pressure vessels because of their superior fracture toughness. However, exposure to high levels of neutron irradiation for extended periods can exacerbate the corrosion fatigue and stress corrosion cracking (SCC) behavior of these steels by affecting the material microchemistry, material microstructure, and water chemistry. Experimental data are presented on crack growth rates of the heat affected zone (HAZ) in Types 304L and 304 SS weld specimens before and after they were irradiated to a fluence of 5.0 x 10{sup 20} n/cm{sup 2} (E > 1 MeV) ({approx} 0.75 dpa) at {approx}288 C. Crack growth tests were conducted under cycling loading and long hold time trapezoidal loading in simulated boiling water reactor environments on Type 304L SS HAZ of the H5 weld from the Grand Gulf reactor core shroud and on Type 304 SS HAZ of a laboratory-prepared weld. The effects of material composition, irradiation, and water chemistry on growth rates are discussed.

  17. In vitro corrosion resistance of plasma source ion nitrided austenitic stainless steels.

    PubMed

    Le, M K; Zhu, X M

    2001-04-01

    Plasma source ion nitriding has emerged as a low-temperature, low-pressure nitriding approach for low-energy implanting nitrogen ions and then diffusing them into steel and alloy. In this work, a single high nitrogen face-centered-cubic (f.c.c.) phase (gammaN) formed on the 1Cr18Ni9Ti and AISI 316L austenitic stainless steels with a high nitrogen concentration of about 32 at % was characterized using Auger electron spectroscopy, electron probe microanalysis, glancing angle X-ray diffraction, and transmission electron microscopy. The corrosion resistance of the gammaN-phase layer was studied by the electrochemical cyclic polarization measurement in Ringer's solutions buffered to pH from 3.5 to 7.2 at a temperature of 37 degrees C. No pitting corrosion in the Ringer's solutions with pH = 7.2 and 5.5 was detected for the gammaN-phase layers on the two stainless steels. The high pitting potential for the gammaN-phase layers is higher, about 500 and 600 mV, above that of the two original stainless steels, respectively, in the Ringer's solution with pH = 3.5. The corroded surface morphologies of the gammaN-phase layers observed by scanning electron microscopy are consistent with the results of the electrochemical polarization measurement. PMID:11246957

  18. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    DOE PAGESBeta

    Sun, C.; Zheng, S.; Wei, C. C.; Wu, Y.; Shao, L.; Yang, Y.; Hartwig, K. T.; Maloy, S. A.; Zinkle, S. J.; Allen, T. R.; et al

    2015-01-15

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size ofmore » ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M₂₃C₆ precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.« less

  19. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    PubMed Central

    Sun, C.; Zheng, S.; Wei, C. C.; Wu, Y.; Shao, L.; Yang, Y.; Hartwig, K. T.; Maloy, S. A.; Zinkle, S. J.; Allen, T. R.; Wang, H.; Zhang, X.

    2015-01-01

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M23C6 precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments. PMID:25588326

  20. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    SciTech Connect

    Sun, C.; Zheng, S.; Wei, C. C.; Wu, Y.; Shao, L.; Yang, Y.; Hartwig, K. T.; Maloy, S. A.; Zinkle, S. J.; Allen, T. R.; Wang, H.; Zhang, X.

    2015-01-15

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M₂₃C₆ precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

  1. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments.

    PubMed

    Sun, C; Zheng, S; Wei, C C; Wu, Y; Shao, L; Yang, Y; Hartwig, K T; Maloy, S A; Zinkle, S J; Allen, T R; Wang, H; Zhang, X

    2015-01-01

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304 L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500 °C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M(23)C(6) precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments. PMID:25588326

  2. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    NASA Astrophysics Data System (ADS)

    Sun, C.; Zheng, S.; Wei, C. C.; Wu, Y.; Shao, L.; Yang, Y.; Hartwig, K. T.; Maloy, S. A.; Zinkle, S. J.; Allen, T. R.; Wang, H.; Zhang, X.

    2015-01-01

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M23C6 precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

  3. Heat resistant process gas line

    SciTech Connect

    Venable, C.R. Jr.

    1987-05-12

    A method is described of forming a heat resistant gas transfer line comprising a tubular metal outer shell, a tubular inner liner formed of prefired refractory rings joined together by shiplap joints having expansion gaps, and an intermediate liner comprising bubble alumina concrete filing the annular space between the inner liner and the outer shell. The method comprises placing on the inside lower surface of the outershell bubble alumina concrete forms capable of supporting the refractory rings in the desired location within the outer shell, securing decomposable rings to the refractory rings in the area where the shiplap joints are to be so that a suitable expansion gap will be provided in the shiplap joints when the combustible rings are destroyed.

  4. Improvement in the Corrosion Resistance of Austenitic Stainless Steel 316L by Ion Implantation

    NASA Astrophysics Data System (ADS)

    Cai, Xun; Feng, Kai

    In the present work, austenitic stainless steel 316L (SS316L) samples were implanted with Ni and Ni-Cr. A nickel-rich layer about 100 nm in thickness and a Ni-Cr enriched layer about 60 nm thick are formed on the surface of SS316L. The effects of ion implantation on the corrosion performance of SS316L are investigated in a 0.5 M H2SO4 with 2 ppm HF solution at 80°C by open circuit potential (OCP), potentiodynamic and potentiostatic tests. The samples after the potentiostatic test are analyzed by XPS. The results indicate that the composition of the passive film change from a mixture of Fe oxides and Cr oxide to a Cr oxide dominated passive film after the potentiostatic test. The solutions after the potentiostatic test are analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results reveal that Fe is selectively dissolved in all cases and a proper Ni and Ni-Cr implant fluence can greatly improve the corrosion resistance of SS316L in the simulated polymer electrolyte membrane fuel cells (PEMFCS) environment. They are in agreement with the electrochemical test results that the bare SS316L has the highest dissolution rate in both cathode and anode environments and the Ni and Ni-Cr implantation reduce markedly the dissolution rate. After the potentiostatic test the interfacial contact resistance (ICR) values are also measured. Ni and Ni-Cr are enriched in the passive film formed in the simulated PEMFC cathode environment after ion implantation thereby providing better conductivity than that formed in the anode one. A significant improvement of ICR is achieved for the SS316L implanted with Ni and Ni-Cr as compared to the bare SS316L, which is attributed to the reduction in passive layer thickness caused by Ni and Ni-Cr implantation. The ICR values for implanted specimens increase with increasing dose.

  5. Overview of strategies for high-temperature creep and oxidation resistance of alumina-forming austenitic stainless steels

    SciTech Connect

    Yamamoto, Yukinori; Brady, Michael P; Santella, Michael L; Bei, Hongbin; Maziasz, Philip J; Pint, Bruce A

    2011-01-01

    A family of creep-resistant, alumina-forming austenitic (AFA) stainless steel alloys is under development for structural use in fossil energy conversion and combustion system applications. The AFA alloys developed to date exhibit comparable creep-rupture lives to state-of-the-art advanced austenitic alloys, and superior oxidation resistance in the {approx}923 K to 1173 K (650 C to 900 C) temperature range due to the formation of a protective Al{sub 2}O{sub 3} scale rather than the Cr{sub 2}O{sub 3} scales that form on conventional stainless steel alloys. This article overviews the alloy design approaches used to obtain high-temperature creep strength in AFA alloys via considerations of phase equilibrium from thermodynamic calculations as well as microstructure characterization. Strengthening precipitates under evaluation include MC-type carbides or intermetallic phases such as NiAl-B2, Fe{sub 2}(Mo,Nb)-Laves, Ni{sub 3}Al-L1{sub 2}, etc. in the austenitic single-phase matrix. Creep, tensile, and oxidation properties of the AFA alloys are discussed relative to compositional and microstructural factors.

  6. Investigation of austenitic alloys for advanced heat recovery and hot gas cleanup systems

    SciTech Connect

    Swindeman, R.W.; Ren, W.

    1995-08-01

    Alloys for design and construction of structural components needed to contain process streams and provide internal structures in advanced heat recovery and hot gas cleanup systems were examined. Emphasis was placed on high-strength, corrosion-resistant alloys for service at temperatures above 1000 {degrees}F (540{degrees}C). Data were collected that related to fabrication, joining, corrosion protection, and failure criteria. Alloys systems include modified type 310 and 20Cr-25Ni-Nb steels and sulfidation-resistance alloys HR120 and HR160. Types of testing include creep, stress-rupture, creep crack growth, fatigue, and post-exposure short-time tensile. Because of the interest in relatively inexpensive alloys for high temperature service, a modified type 310 stainless steel was developed with a target strength of twice that for standard type 310 stainless steel.

  7. Integrity assessment of the ferritic / austenitic dissimilar weld joint between intermediate heat exchanger and steam generator in fast reactor

    SciTech Connect

    Jayakumar, T.; Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Goyal, S.; Kumar, J. G.; Mathew, M. D.

    2012-07-01

    Integrity of the modified 9Cr-1Mo / alloy 800 dissimilar joint welded with Inconel 182 electrodes has been assessed under creep condition based on the detailed analysis of microstructure and stress distribution across the joint by finite element analysis. A hardness peak at the ferritic / austenitic weld interface and a hardness trough at the inter-critical heat affected zone (HAZ) in ferritic base metal developed. Un-tempered martensite was found at the ferritic / austenitic weld interface to impart high hardness in it; whereas annealing of martensitic structure of modified 9Cr-1Mo steel by inter-critical heating during welding thermal cycle resulted in hardness tough in the inter-critical HAZ. Creep tests were carried out on the joint and ferritic steel base metal at 823 K over a stress range of 160-320 MPa. The joint possessed lower creep rupture strength than its ferritic steel base metal. Failure of the joint at relatively lower stresses occurred at the ferritic / austenitic weld interface; whereas it occurred at inter-critical region of HAZ at moderate stresses. Cavity nucleation associated with the weld interface particles led to premature failure of the joint. Finite element analysis of stress distribution across the weld joint considering the micro-mechanical strength inhomogeneity across it revealed higher von-Mises and principal stresses at the weld interface. These stresses induced preferential creep cavitation at the weld interface. Role of precipitate in enhancing creep cavitation at the weld interface has been elucidated based on the FE analysis of stress distribution across it. (authors)

  8. Delta ferrite-containing austenitic stainless steel resistant to the formation of undesirable phases upon aging

    SciTech Connect

    Leitnaker, J.M.

    1981-05-05

    Austenitic stainless steel alloys containing delta ferrite, such as are used as weld deposits, are protected against the transformation of delta ferrite to sigma phase during aging by the presence of carbon plus nitrogen in a weight percent 015-0.030 times the volume percent ferrite present in alloy. The formation of chi phase upon aging is controlled by controlling the mo content.

  9. Austenitic stainless steel alloys having improved resistance to fast neutron-induced swelling

    DOEpatents

    Bloom, Everett E.; Stiegler, James O.; Rowcliffe, Arthur F.; Leitnaker, James M.

    1977-03-08

    The present invention is based on the discovery that radiation-induced voids which occur during fast neutron irradiation can be controlled by small but effective additions of titanium and silicon. The void-suppressing effect of these metals in combination is demonstrated and particularly apparent in austenitic stainless steels.

  10. Spore heat resistance and specific mineralization.

    PubMed Central

    Bender, G R; Marquis, R E

    1985-01-01

    Spores of Bacillus megaterium ATCC 19213, Bacillus subtilis niger and Bacillus stearothermophilus ATCC 7953 were converted to fully demineralized, but viable, H forms by controlled acid titration. H forms were more heat sensitive than were native forms, but z values were greater for killing of H spores than those for native spores. Therefore, the differences in heat sensitivity between native and H forms decreased with increasing killing temperature. The increase in heat sensitivity associated with demineralization did not appear to be due to damage to cortex lytic enzymes of the germination system because it could not be moderated by decoating heated H spores and plating them on medium with added lysozyme. H spores could be remineralized by means of back titration with appropriate base solutions. The remineralized spores, except for the Na form, were then more heat resistant than were H spores. Ca and Mn were more effective in restoring resistance than were Mg and K. Generally, the remineralized forms (except for the Na form) had z values greater than those of the native forms but still less than those of the H forms. At lower killing temperatures, the reinstatement of resistance could be related to the extent of remineralization. However, at higher killing temperatures, only a fraction of the mineral was effective in restoring resistance, and higher levels of remineralization did not result in greater resistance. Mineralization is clearly an important factor in spore heat resistance, but the relationship between resistance and mineralization is complex and dependent on killing temperature. PMID:3937495

  11. Resistance heating releases structural adhesive

    NASA Technical Reports Server (NTRS)

    Glemser, N. N.

    1967-01-01

    Composite adhesive package bonds components together for testing and enables separation when testing is completed. The composite of adhesives, insulation and a heating element separate easily when an electrical current is applied.

  12. 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).

  13. Effects of surface preparation on pitting resistance, residual stress, and stress corrosion cracking in austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Rhouma, A. Ben; Sidhom, H.; Braham, C.; Lédion, J.; Fitzpatrick, M. E.

    2001-10-01

    Surface finishing treatments such as shot blasting and wire brushing can be beneficial in improving the integrity of machined surfaces of austenitic stainless steels. These operations optimize in-service properties such as resistance to pitting corrosion and stress corrosion cracking (SCC). In this study, ground steel surfaces were subjected to a series of sand blasting and wire brushing treatments. The surfaces were then characterized by their hardness, surface residual stress state, and resistance to stress corrosion and pitting corrosion. Some samples were selected for depth profiling of residual stress. It is found that surface hardening and the generation of near-surface compressive residual stress are the benefits that can be introduced by sand blasting and brushing operations.

  14. Investigation of austenitic alloys for advanced heat recovery and hot gas cleanup systems

    SciTech Connect

    Swindeman, R.W.; Ren, W.

    1996-08-01

    Materials properties were collected for the design and construction of structural components for use in advanced heat recovery and hot gas cleanup systems. Alloys systems included 9Cr-1Mo-V steel, modified 316 stainless steel, modified type 310 stainless steel, modified 20Cr-25Ni-Nb stainless steel, modified alloy 800, and two sulfidation resistant alloys: HR160 and HR120. Experimental work was undertaken to expand the databases for potentially useful alloys. Types of testing included creep, stress-rupture, creep-crack growth, fatigue, and post-exposure short-time tensile tests. Because of the interest in relatively inexpensive alloys for service at 700{degrees}C and higher, research emphasis was placed on a modified type 310 stainless steel and a modified 20Cr-25Ni-Nb stainless steel. Both steels were found to have useful strength to 925{degrees}C with good weldability and ductility.

  15. Improvement of the resistance to stress corrosion cracking in austenitic stainless steels by cyclic prestraining

    SciTech Connect

    Chambreuil-Paret, A.; Magnin, T.

    1999-05-01

    Austenitic stainless steels are known to be sensitive to stress corrosion cracking (SCC) in hot chloride solutions. The aim of the present study is to find improvements in the SCC behavior of 316L-type austenitic stainless steels in 117 C MgCl{sub 2} solutions. Previously, the authors have proposed the corrosion-enhanced plasticity model (CEPM) to describe the discontinuous cracking process which occurs in SCC. This model is based on localized corrosion (anodic dissolution, and hydrogen absorption)-deformation (dislocations) interactions (CDI). From the framework of this model, it is proposed that a prestraining in fatigue at saturation decreases the SCC sensitivity. This idea is experimentally confirmed for both crack initiation and crack propagation, through the analysis of the SCC behavior by slow-strain-rate tests of single and polycrystals after different prestraining conditions.

  16. Delta ferrite-containing austenitic stainless steel resistant to the formation of undesirable phases upon aging

    DOEpatents

    Leitnaker, J.M.

    Austenitic stainless steel alloys containing delta ferrite, such as are used as weld deposits, are protected against the transformation of delta ferrite to sigma phase during aging by the presence of carbon plus nitrogen in a weight percent 0.015 to 0.030 times the volume percent ferrite present in the alloy. The formation of chi phase upon aging is controlled by controlling the Mo content.

  17. Delta ferrite-containing austenitic stainless steel resistant to the formation of undesirable phases upon aging

    DOEpatents

    Leitnaker, James M.

    1981-01-01

    Austenitic stainless steel alloys containing delta ferrite, such as are used as weld deposits, are protected against the transformation of delta ferrite to sigma phase during aging by the presence of carbon plus nitrogen in a weight percent 0.015-0.030 times the volume percent ferrite present in the alloy. The formation of chi phase upon aging is controlled by controlling the Mo content.

  18. High Nb, Ta, and Al creep- and oxidation-resistant austenitic stainless steel

    DOEpatents

    Brady, Michael P [Oak Ridge, TN; Santella, Michael L [Knoxville, TN; Yamamoto, Yukinori [Oak Ridge, TN; Liu, Chain-tsuan [Oak Ridge, TN

    2010-07-13

    An austenitic stainless steel HTUPS alloy includes, in weight percent: 15 to 30 Ni; 10 to 15 Cr; 2 to 5 Al; 0.6 to 5 total of at least one of Nb and Ta; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1 W; up to 0.5 Cu; up to 4 Mn; up to 1 Si; 0.05 to 0.15 C; up to 0.15 B; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni wherein said alloy forms an external continuous scale comprising alumina, nanometer scale sized particles distributed throughout the microstructure, said particles comprising at least one composition selected from the group consisting of NbC and TaC, and a stable essentially single phase fcc austenitic matrix microstructure, said austenitic matrix being essentially delta-ferrite-free and essentially BCC-phase-free.

  19. Improved heat-resistant garments

    NASA Technical Reports Server (NTRS)

    Johnston, R. S.

    1970-01-01

    Fabrication method for protective clothing eliminates the common heat-short by avoiding the stitch which is common to all layers, and preventing external exposure of any stitch to the outer environment. A unique overlap arrangement is described and additional protective methods are discussed.

  20. Plasma treatment of heat-resistant materials

    NASA Astrophysics Data System (ADS)

    Vlasov, V. A.; Kosmachev, P. V.; Skripnikova, N. K.; Bezukhov, K. A.

    2015-11-01

    Refractory lining of thermal generating units is exposed to chemical, thermal, and mechanical attacks. The degree of fracture of heat-resistant materials depends on the chemical medium composition, the process temperature and the material porosity. As is known, a shortterm exposure of the surface to low-temperature plasma (LTP) makes possible to create specific coatings that can improve the properties of workpieces. The aim of this work is to produce the protective coating on heat-resistant chamotte products using the LTP technique. Experiments have shown that plasma treatment of chamotte products modifies the surface, and a glass-ceramic coating enriched in mullite is formed providing the improvement of heat resistance. For increasing heat resistance of chamotte refractories, pastes comprising mixtures of Bacor, alumina oxide, and chamot were applied to their surfaces in different ratios. It is proved that the appropriate coating cannot be created if only one of heat-resistant components is used. The required coatings that can be used and recommended for practical applications are obtained only with the introduction of powder chamot. The paste composition of 50% chamot, 25% Bacor, and 25% alumina oxide exposed to plasma treatment, has demonstrated the most uniform surface fusion.

  1. Some Properties of Heat-Resistant and Heat-Sensitive Strains of Clostridium perfringens I. Heat Resistance and Toxigenicity1

    PubMed Central

    Weiss, Karl F.; Strong, Dorothy H.

    1967-01-01

    Heat resistance at 100 C (D-values), sporulating ratios, toxigenicity for mice, and lecithinase activity (as micrograms per milliliter of enzyme, ascertained by the lecithovitellin reaction) were determined for four strains of Clostridium perfringens. A definite inverse relationship between thermal resistance and toxigenicity was found. The D-values ranged from 17.6 for the most heat-resistant strain to 0.3 for the strain possessing the least heat resistance, with corresponding lecithinase activities from 25 to 133 μg/ml of enzyme. The sporulating ratios did not differ greatly between the strains. The heat stability of the toxin was greater at 100 C than at 75 C. There was a noticeable difference between the heat stabilities of the toxin in the culture fluids of the heat-sensitive and heat-resistant strains at pH 7.0 when the toxic filtrates were held at 100 C. At a holding temperature of 75 C, a similar but lesser difference was observed at pH 5.5. Heat resistance and lecithinase activity did not change when a substrain of the least heat-resistant parent strain was obtained through heat selection by a single transfer, or when the most heat-resistant strain was transferred serially 12 times. PMID:4289809

  2. The Effect of Aging Heat Treatment on the Microstructure and Mechanical Properties of 10Cr20Ni25Mo1.5NbN Austenitic Steel

    NASA Astrophysics Data System (ADS)

    Liang, Zhiyuan; Sha, Wanhua; Zhao, Qinxin; Wang, Chongbin; Wang, Jianyong; Jiang, Weiwei

    2016-01-01

    The effect of aging heat treatment on the microstructure and mechanical properties of 10Cr20Ni25Mo1.5NbN austenitic steel was investigated in this article. The microstructure was characterized by scanning electron microscopy, energy dispersive spectrometry and transmission electron microscopy. Results show that the microstructure of 10Cr20Ni25Mo1.5NbN austenitic is composed of austenite. This steel was strengthened by precipitates of secondary phases that were mainly M23C6 carbides and NbCrN nitrides. As aging treatment time increased, the tensile strength first rose (0-3,000 h) and then fell (3,000-5,000 h) due to the decrease of high density of dislocations. The impact absorbed energy decreased sharply, causing the sulfides to precipitate at the grain boundary. Therefore, the content of sulfur should be strictly controlled in the steelmaking process.

  3. Turbulent resistive heating of solar coronal arches

    NASA Technical Reports Server (NTRS)

    Benford, G.

    1983-01-01

    The possibility that coronal heating occurs by means of anomalous Joule heating by electrostatic ion cyclotron waves is examined, with consideration given to currents running from foot of a loop to the other. It is assumed that self-fields generated by the currents are absent and currents follow the direction of the magnetic field, allowing the plasma cylinder to expand radially. Ion and electron heating rates are defined within the cylinder, together with longitudinal conduction and convection, radiation and cross-field transport, all in terms of Coulomb and turbulent effects. The dominant force is identified as electrostatic ion cyclotron instability, while ion acoustic modes remain stable. Rapid heating from an initial temperature of 10 eV to 100-1000 eV levels is calculated, with plasma reaching and maintaining a temperature in the 100 eV range. Strong heating is also possible according to the turbulent Ohm's law and by resistive heating.

  4. Gas-Solid Interactions During Nonisothermal Heat Treatment of a High-Strength CrMnCN Austenitic Steel Powder: Influence of Atmospheric Conditions and Heating Rate on the Densification Behavior

    NASA Astrophysics Data System (ADS)

    Krasokha, Nikolaj; Weber, Sebastian; Huth, Stephan; Zumsande, Kathrin; Theisen, Werner

    2012-11-01

    This work deals with gas-solid interactions between a high-alloyed steel powder and the surrounding atmosphere during continuous heating. It is motivated by the recently developed corrosion-resistant CrMnCN austenitic cast steels. Here, powder metallurgical processing would be desirable to manufacture highly homogeneous parts and/or novel corrosion-resistant metal-matrix composites. However, the successful use of this new production route calls for a comprehensive investigation of interactions between the sintering atmosphere and the metallic powder to prevent undesirable changes to the chemical composition, e.g., degassing of nitrogen or evaporation of manganese. In this study, dilatometric measurements combined with residual gas analysis, high-temperature X-ray diffraction (XRD) measurements, and thermodynamic equilibrium calculations provided detailed information about the influence of different atmospheric conditions on the microstructure, constitution, and densification behavior of a gas-atomized CrMnCN steel powder during continuous heating. Intensive desorption of nitrogen led to the conclusion that a vacuum atmosphere is not suitable for powder metallurgical (PM) processing. Exposure to an N2-containing atmosphere resulted in the formation of nitrides and lattice expansion. Experimental findings have shown that the N content can be controlled by the nitrogen partial pressure. Furthermore, the reduction of surface oxides because of a carbothermal reaction at elevated temperatures and the resulting enhancement of the powder's densification behavior are discussed in this work.

  5. Heat- and chemical-resistant oxdiazole elastomers

    NASA Technical Reports Server (NTRS)

    Rosser, R. W.; Kwong, H.; Shalhoub, I. M.

    1980-01-01

    Heat and chemical resistant polymers with triazine crosslinks are prepared by thermal condensation reactions to form 1,2,4-oxdiazole linkages. They are compounded with variety of fillers, extenders, and modifiers for numerous applications in which stability, impermiability to liquids and gases, good plasticity, and elasticity or rigidity are important.

  6. Simulation of the elastic deformation of laser-welded joints of an austenitic corrosion-resistant steel and a titanium alloy with an intermediate copper insert

    NASA Astrophysics Data System (ADS)

    Pugacheva, N. B.; Myasnikova, M. V.; Michurov, N. S.

    2016-02-01

    The macro- and microstructures and the distribution of elements and of the values of the microhardness and contact modulus of elasticity along the height and width of the weld metal and heat-affected zone of austenitic corrosion-resistant 12Kh18N10T steel (Russian analog of AISI 321) and titanium alloy VT1-0 (Grade 2) with an intermediate copper insert have been studied after laser welding under different conditions. The structural inhomogeneity of the joint obtained according to one of the regimes selected has been shown: the material of the welded joint represents a supersaturated solid solution of Fe, Ni, Cr, and Ti in the crystal lattice of copper with a uniformly distributed particles of intermetallic compounds Ti(Fe,Cr) and TiCu3. At the boundaries with steel and with the titanium alloy, diffusion zones with thicknesses of 0.1-0.2 mm are formed that represent supersaturated solid solutions based on iron and titanium. The strength of such a joint was 474 MPa, which corresponds to the level of strength of the titanium alloy. A numerical simulation of the mechanical behavior of welded joints upon the elastic tension-compression has been performed taking into account their structural state, which makes it possible to determine the amplitude values of the deformations of the material of the weld.

  7. Heat and chemical resistance of enterococci.

    PubMed

    Bradley, C R; Fraise, A P

    1996-11-01

    Recent reports have highlighted the tolerance of vancomycin-resistant strains of enterococci to heat. This study examined the tolerance of vancomycin-resistant and sensitive strains of enterococci and an NCTC type strain to 65, 71 and 80 degrees C, and also to low concentrations of a chlorine-releasing agent, alcohol and glutaraldehyde. Variation in the tolerance to chemicals was observed but there was no correlation between vancomycin resistance and tolerance to chemical disinfectants. The NCTC type strain was killed within the time/temperature parameters set by the Department of Health for thermal washer/disinfectors, i.e. 65 degrees C for 10 min, 71 degrees C for 3 min and 80 degrees C for 1 min. However, the clinical strains showed varying resistance to heat, irrespective of their vancomycin susceptibility. One strain survived 80 degrees C for 3 min. These results showed that clinical isolates can be resistant to commonly used disinfection processes, although the practical significance of these results is debatable. PMID:8923273

  8. Hot Ductility Behaviors in the Weld Heat-Affected Zone of Nitrogen-Alloyed Fe-18Cr-10Mn Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Tae-Ho; Hong, Hyun-Uk

    2015-04-01

    Hot ductility behaviors in the weld heat-affected zone (HAZ) of nitrogen-alloyed Fe-18Cr-10Mn austenitic stainless steels with different nitrogen contents were evaluated through hot tension tests using Gleeble simulator. The results of Gleeble simulations indicated that hot ductility in the HAZs deteriorated due to the formation of δ-ferrite and intergranular Cr2N particles. In addition, the amount of hot ductility degradation was strongly affected by the fraction of δ-ferrite.

  9. Method for producing heat-resistant semi-inorganic compounds

    NASA Technical Reports Server (NTRS)

    Yajima, S.; Okamura, K.; Shishido, T.; Hasegawa, Y.

    1983-01-01

    The method for producing a heat resistant, semi-inorganic compound is discussed. Five examples in which various alcohols, phenols, and aromatic carbonic acids are used to test heat resistance and solubility are provided.

  10. Intergranular Cracking Susceptibility of 2.25Cr Heat-Resistant Steels Depending on Alloying Elements and Impurities

    NASA Astrophysics Data System (ADS)

    Sung, Hyun Je; Heo, Nam Hoe; Kim, Sung-Joon

    2016-05-01

    The intergranular cracking susceptibility of 2.25Cr heat-resistant steels increases with increasing bulk phosphorus content. This is due to the increase in phosphorus segregation concentration of prior austenite grain boundaries (PAGBs) and the prior austenite grain boundary/carbide interfaces (GCIs) with increasing bulk phosphorus content. Moreover, the susceptibility is higher in tungsten-added steels than the molybdenum-added steel. This is attributed to the higher driving force for carbide formation of tungsten which causes more active carbide formation in the tungsten-added steel, the consequent absence of the repulsive segregation between carbon and phosphorus, and the final higher phosphorus segregation concentration at the PAGBs and the GCIs. Additionally, the absence of sulfur segregation at the PAGBs and the GCIs of the molybdenum-added steel, which arises from the repulsive segregation between carbon and sulfur, acts as an additional factor which lowers the intergranular cracking susceptibility.

  11. Investigation of austenitic alloys for advanced heat recovery and hot gas cleanup systems

    SciTech Connect

    Swindeman, R.W.; Ren, W.

    1996-06-01

    The objective of the research is to provide databases and design criteria to assist in the selection of optimum alloys for construction of components needed to contain process streams in advanced heat recovery and hot-gas cleanup systems. Typical components include: steam line piping and superheater tubing for low emission boilers (600 to 700{degrees}C), heat exchanger tubing for advanced steam cycles and topping cycle systems (650 to 800{degrees}C), foil materials for recuperators, on advanced turbine systems (700 to 750{degrees}C), and tubesheets for barrier filters, liners for piping, cyclones, and blowback system tubing for hot-gas cleanup systems (850 to 1000{degrees}C). The materials being examined fall into several classes, depending on which of the advanced heat recovery concepts is of concern. These classes include martensitic steels for service to 650{degrees}C, lean stainless steels and modified 25Cr-30Ni steels for service to 700{degrees}C, modified 25Cr-20Ni steels for service to 900{degrees}C, and high Ni-Cr-Fe or Ni-Cr-Co-Fe alloys for service to 1000{degrees}C.

  12. Improved Erosion Resistance of Austenitic Stainless Steel in Corrosive Environment with Gas Tungsten Arc Melt Injection

    NASA Astrophysics Data System (ADS)

    Liu, Aiguo; Guo, Mianhuan; Ma, Yinan; Hu, Hailong

    2013-06-01

    Cr3C2-NiCr particles were injected into surface of 304 stainless steel using a gas tungsten arc melt injection process. Microstructure, composition, and phases in the treated layer were characterized. Hardness of the treated layer was tested. Corrosion resistance and erosion resistance of the treated layer were tested in 5 wt.% NaCl aqueous solution. Polarization curve was obtained by an electrochemical measuring system. An untreated substrate was tested for comparison. The results showed that large amount of (Cr, Fe)7C3 carbides were formed in the treated layer. Corrosion potential of the substrate was increased from -1.04 to -0.618 V. But the passivation effect was weakened, and the corrosion current density became higher. The hardness of the treated layer was greatly improved, from Hv245.0 to Hv1098.9. The erosion resistance of the treated layer was 1.5 times higher than that of the untreated substrate.

  13. Investigation of austenitic alloys for advanced heat recovery and hot gas cleanup systems

    SciTech Connect

    Swindeman, R.W.

    1993-07-01

    Commercial and developmental alloys were evaluated in support of advanced steam cycle and combined cycle technology. Working with industrial groups, Grade 91 steel, which is a candidate for main steam line piping and superheater tubing in advanced steam cycle plants, was re-evaluated to examine metallurgical factors that influence long-time performance to 600{degree}C. Deformation models and aging effect models were developed. Testing of corrosion-resistant filler metals for tubing was extended to times approaching 30,000 h. Good strengths were observed. Modified Type 310 stainless steels were examined to 927{degree}C. It was found that these steels had up to twice the strength of standard Type 310H stainless steel. The behavior of aluminum-bearing, alloys and high chromium alloys was examined for potential applications to 870{degree}C. Thermal cycling of clad tubing was undertaken, and good performance was found.

  14. Genetic determinants of heat resistance in Escherichia coli

    PubMed Central

    Mercer, Ryan G.; Zheng, Jinshui; Garcia-Hernandez, Rigoberto; Ruan, Lifang; Gänzle, Michael G.; McMullen, Lynn M.

    2015-01-01

    Escherichia coli AW1.7 is a heat resistant food isolate and the occurrence of pathogenic strains with comparable heat resistance may pose a risk to food safety. To identify the genetic determinants of heat resistance, 29 strains of E. coli that differed in their of heat resistance were analyzed by comparative genomics. Strains were classified as highly heat resistant strains, exhibiting a D60-value of more than 6 min; moderately heat resistant strains, exhibiting a D60-value of more than 1 min; or as heat sensitive. A ~14 kb genomic island containing 16 predicted open reading frames encoding putative heat shock proteins and proteases was identified only in highly heat resistant strains. The genomic island was termed the locus of heat resistance (LHR). This putative operon is flanked by mobile elements and possesses >99% sequence identity to genomic islands contributing to heat resistance in Cronobacter sakazakii and Klebsiella pneumoniae. An additional 41 LHR sequences with >87% sequence identity were identified in 11 different species of β- and γ-proteobacteria. Cloning of the full length LHR conferred high heat resistance to the heat sensitive E. coli AW1.7ΔpHR1 and DH5α. The presence of the LHR correlates perfectly to heat resistance in several species of Enterobacteriaceae and occurs at a frequency of 2% of all E. coli genomes, including pathogenic strains. This study suggests the LHR has been laterally exchanged among the β- and γ-proteobacteria and is a reliable indicator of high heat resistance in E. coli. PMID:26441869

  15. Investigation of austenitic alloys for advanced heat recovery and hot-gas cleanup systems

    SciTech Connect

    Swindeman, R.W.

    1997-12-01

    Materials properties were collected for the design and construction of structural components for use in advanced heat recovery and hot gas cleanup systems. Alloys systems included 9Cr-1Mo-V steel, modified 316 stainless steel, modified type 310 stainless steel, modified 20Cr-25Ni-Nb stainless steel, and modified alloy 800. Experimental work was undertaken to expand the databases for potentially useful alloys. Types of testing included creep, stress-rupture, creep-crack growth, fatigue, and post-exposure short-time tensile tests. Because of the interest in relatively inexpensive alloys for service at 700 C and higher, research emphasis was placed on a modified type 310 stainless steel and a modified 20Cr-25Ni-Nb stainless steel. Both steels were found to have useful strength to 925 C with good weldability and ductility.

  16. Heat resistance poly(vinyl alcohol) hydrogel

    NASA Astrophysics Data System (ADS)

    Yoshii, F.; Makuuchi, K.; Darwis, D.; Iriawan, T.; Razzak, M. T.; Rosiak, Janusz M.

    1995-08-01

    Six methods were used to evaluate the heat resistance of poly(vinyl alcohol) (PVA) hydrogel prepared by a combination of electron beam irradiation and acetalization of PVA. The physical properties of the hydrogel depended on the degree of acetilization which was affected by content of water in PVA sheet of acetalization in formaldehyde solution at 60°C. It was found that the optimum water content was 20-30%. The acetalized PVA sheet gave maximum tensile strength in electron beams irradiation at 100 kGy. The tensile strength of the hydrogel film increased to 20 MPa from 14 MPa by the irradiation. Heat resistance of the hydrogel was evaluated by measuring the mechanical properties after sterilization in a steam autoclave at 121°C for 90 min. The tensile strength decreased to 10 MPa whereas the elongation at break increased to 300%. The tackiness of the hydrogel was improved by radiation grafting of acrylic acid. Wholesomeness of the hydrogel as a wound dressing was evaluated by attaching to a burn or wound of the back skin of marmots. Advantages of the hydrogel over a gauze dressing were homogeneous adhesion to the affected parts, easy removal without damage to renewed skin and slightly faster rate of reconstruction of the injured skin.

  17. Atomic-scale decoration for improving the pitting corrosion resistance of austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    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.

  18. Atomic-scale decoration for improving the pitting corrosion resistance of austenitic stainless steels.

    PubMed

    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 Cu(2+)-containing solutions. This chemical bath generates Cu(2-δ)S 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

  19. 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

  20. Microstructure of heat resistant chromium steel weld metals

    NASA Astrophysics Data System (ADS)

    Andrén, Hans-Olof; Cai, Guangjun; Svensson, Lars-Erik

    1995-03-01

    The microstructure of weld metals of 2.25Cr-1Mo, 5Cr-0.5Mo, 9Cr-1Mo and 12Cr-1Mo type steels was studied with electron microscopy and atom probe field ion microscopy. Many different types of carbides and nitrides precipitated during welding and post-weld heat treatment (MC, M 2C, M 3C, M 7C 3, M 23C 6, MN, M 2N). The eutectoid decomposition of retained austenite gave large aggregates of carbides which were found to be detrimental to the impact toughness of the weld metal.

  1. Observations of Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Spot Welds Using Time Resolved X-Ray Diffraction

    SciTech Connect

    Palmer, T; Elmer, J; Babu, S

    2003-10-29

    Time Resolved X-Ray Diffraction (TRXRD) measurements are made in the Heat Affected Zone (HAZ) of 2205 Duplex Stainless Steel (DSS) spot welds. Both the {gamma} {yields} {delta} and {delta} {yields} {gamma} transformations are monitored as a function of time during the rapid spot weld heating and cooling cycles. These observations are then correlated with calculated thermal cycles. Where the peak temperatures are highest ({approx}1342 C), the {gamma} {yields} {delta} transformation proceeds to completion, leaving a ferritic microstructure at the end of heating. With lower peak temperatures, the {gamma} {yields} {delta} transformation proceeds to only partial completion, resulting in a microstructure containing both transformed and untransformed austenite. Further analyses of the individual diffraction patterns show shifts in the peak positions and peak widths as a function of both time and temperature. In addition, these changes in the peak characteristics are correlated with measured changes in the ferrite volume fraction. Such changes in the peak positions and widths during the {gamma} {yields} {delta} transformation provide an indication of changes occurring in each phase. These changes in peak properties can be correlated with the diffusion of nitrogen and other substitutional alloying elements, which are recognized as the primary mechanisms for this transformation. Upon cooling, the {delta} {yields} {gamma} transformation is observed to proceed from both the completely and partially transformed microstructural regions in the TRXRD data. An examination of the resulting microstructures confirms the TRXRD observation as the evidence shows that austenite both nucleates and grows from the ferritic microstructure at locations closest to the fusion zone boundary and grows from untransformed austenite grains at locations further from this boundary.

  2. Direct estimation of austenitic grain dimensions in heat affected zones of a martensitic steel from EBSD images.

    PubMed

    Altendorf, H; Faessel, M; Jeulin, D; Latourte, F

    2015-05-01

    In the context of automated analyses of electron-backscattered-diffraction images, we present in this paper a novel method to automatically extract morphological properties of prior austenitic grains in martensitic steels based on raw crystallographic orientation maps. This quantification includes the estimation of the mean chord length in specific directions, with in addition the reconstruction of the mean shape of austenitic grains inducing anisotropic shape properties. The approach is based on the morphological measure of covariance on a decision curve of grain fidelity per disorientation angle. These efforts have been motivated by the need of realistic microstructures to perform micromechanical studies of grain boundary localized damage phenomenons in steels, one example being the type IV fracture phenomenon occurring in welded joints of grade P91/P92 steel. This failure is attributed to a change of the microstructure due to thermal gradients arising during the welding process. To precisely capture the relationships between microstructural changes and mechanical fields localization in a polycrystalline aggregate, we first need to achieve a reasonable stochastic model of its microstructure, which relies on a detailed knowledge of the microstructural morphology. As martensitic steels possess multiscale microstructures composed of prior austenitic grains, packets and laths, a relevant modelling strategy has to be proposed to account for the observed hierarchies. With this objective, this paper focuses on the larger scale entities present in the microstructure, namely, the austenitic grains. PMID:25689129

  3. Hypersonic Composites Resist Extreme Heat and Stress

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Through research contracts with NASA, Materials and Electrochemical Research Corporation (MER), of Tucson, Arizona, contributed a number of technologies to record-breaking hypersonic flights. Through this research, MER developed a coating that successfully passed testing to simulate Mach 10 conditions, as well as provide several additional carbon-carbon (C-C) composite components for the flights. MER created all of the leading edges for the X-43A test vehicles at Dryden-considered the most critical parts of this experimental craft. In addition to being very heat resistant, the coating had to be very lightweight and thin, as the aircraft was designed to very precise specifications and could not afford to have a bulky coating. MER patented its carbon-carbon (C-C) composite process and then formed a spinoff company, Frontier Materials Corporation (FMC), also based in Tucson. FMC is using the patent in conjunction with low-cost PAN (polyacrylonitrile)-based fibers to introduce these materials to the commercial markets. The C-C composites are very lightweight and exceptionally strong and stiff, even at very high temperatures. The composites have been used in industrial heating applications, the automotive and aerospace industries, as well as in glass manufacturing and on semiconductors. Applications also include transfer components for glass manufacturing and structural members for carrier support in semiconductor processing.

  4. A Feasibility Study on Low Temperature Thermochemical Treatments of Austenitic Stainless Steel in Fluidized Bed Furnace

    NASA Astrophysics Data System (ADS)

    Haruman, Esa; Sun, Yong; Triwiyanto, Askar; Manurung, Yupiter H. P.; Adesta, Erry Y.

    2011-04-01

    In this work, the feasibility of using an industrial fluidized bed furnace to perform low temperature thermochemical treatments of austenitic stainless steels has been studied, with the aim to produce expanded austenite layers with combined wear and corrosion resistance, similar to those achievable by plasma and gaseous processes. Several low temperature thermochemical treatments were studied, including nitriding, carburizing, combined nitridingcarburizing (hybrid treatment), and sequential carburizing and nitriding. The results demonstrate that it is feasible to produce expanded austenite layers on the investigated austenitic stainless steel by the fluidized bed heat treatment technique, thus widening the application window for the novel low temperature processes. The results also demonstrate that the fluidized bed furnace is the most effective for performing the hybrid treatment, which involves the simultaneous incorporation of nitrogen and carbon together into the surface region of the component in nitrogen and carbon containing atmospheres. Such hybrid treatment produces a thicker and harder layer than the other three processes investigated.

  5. A Comparison of the Corrosion Resistance of Iron-Based Amorphous Metals and Austenitic Alloys in Synthetic Brines at Elevated Temperature

    SciTech Connect

    Farmer, J C

    2008-11-25

    Several hard, corrosion-resistant and neutron-absorbing iron-based amorphous alloys have now been developed that can be applied as thermal spray coatings. These new alloys include relatively high concentrations of Cr, Mo, and W for enhanced corrosion resistance, and substantial B to enable both glass formation and neutron absorption. The corrosion resistances of these novel alloys have been compared to that of several austenitic alloys in a broad range of synthetic brines, with and without nitrate inhibitor, at elevated temperature. Linear polarization and electrochemical impedance spectroscopy have been used for in situ measurement of corrosion rates for prolonged periods of time, while scanning electron microscopy (SEM) and energy dispersive analysis of X-rays (EDAX) have been used for ex situ characterization of samples at the end of tests. The application of these new coatings for the protection of spent nuclear fuel storage systems, equipment in nuclear service, steel-reinforced concrete will be discussed.

  6. High post-irradiation ductility thermomechanical treatment for precipitation strengthened austenitic alloys

    DOEpatents

    Laidler, James J.; Borisch, Ronald R.; Korenko, Michael K.

    1982-01-01

    A method for improving the post-irradiation ductility is described which prises a solution heat treatment following which the materials are cold worked. They are included to demonstrate the beneficial effect of this treatment on the swelling resistance and the ductility of these austenitic precipitation hardenable alloys.

  7. Effect of chemical composition and ferrite content on room temperature SCC behavior of austenitic weld metals

    SciTech Connect

    Raghunatha Rao, B.; Prasad Rao, K.; Iyer, K.J.L. )

    1993-03-01

    Austenitic stainless steels are widely used in the welded condition especially in chemical, petrochemical, thermal power, and nuclear industries where they are subjected to stresses in corrosive environments. Since austenitic stainless steel weld metals invariably contain some delta ferrite to avoid hot cracking, the effect of ferrite on the stress corrosion cracking behavior is important. Austenitic weld metals with different alloy additions and different ferrite contents were investigated for their resistance to room temperature stress corrosion cracking (SCC) in 5 N H[sub 2]SO[sub 4] + 0.5 N NaCl solution. It was found that the delta ferrite content in the weld metals had a predominant effect on the SCC resistance. Higher ferrite contents increased the tendency for SCC. Post-weld heat treatment of weld metals resulted in the improvement of the SCC resistance.

  8. Effect of Friction-Induced Deformation on the Structure, Microhardness, and Wear Resistance of Austenitic Chromium—Nickel Stainless Steel Subjected to Subsequent Oxidation

    NASA Astrophysics Data System (ADS)

    Korshunov, L. G.; Chernenko, N. L.

    2016-03-01

    The effect of plastic deformation that occurs in the zone of the sliding friction contact on structural transformations in the 12Kh18N9T austenitic steel subjected to subsequent 1-h oxidation in air at temperatures of 300-800°C, as well as on its wear resistance, has been studied. It has been shown that severe deformation induced by dry sliding friction produces the two-phase nanocrystalline γ + α structure in the surface layer of the steel ~10 μm thick. This structure has the microhardness of 5.2 GPa. Subsequent oxidation of steel at temperatures of 300-500°C leads to an additional increase in the microhardness of its deformed surface layer to the value of 7.0 GPa. This is due to the active saturation of the austenite and the strain-assisted martensite (α') with the oxygen atoms, which diffuse deep into the metal over the boundaries of the γ and α' nanocrystals with an increased rate. The concentration of oxygen in the surface layer of the steel and in wear products reaches 8 wt %. The atoms of the dissolved oxygen efficiently pin dislocations in the γ and α' phases, which enhances the strength and wear resistance of the surface of the 12Kh18N9T steel. The oxidation of steel at temperatures of 550-800°C under a light normal load (98 N) results in the formation of a large number of Fe3O4 (magnetite) nanoparticles, which increase the resistance of the steel to thermal softening and its wear resistance during dry sliding friction in a pair with 40Kh13 steel. Under a heavy normal load (196 N), the toughness of 12Kh18N9T steel and, therefore, the wear resistance of its surface layer decrease due to the presence of the brittle oxide phase.

  9. Assessment of Retained Austenite in AISI D2 Tool Steel Using Magnetic Hysteresis and Barkhausen Noise Parameters

    NASA Astrophysics Data System (ADS)

    Kahrobaee, Saeed; Kashefi, Mehrdad

    2015-03-01

    Inaccurate heat treatment process could result in excessive amount of retained austenite, which degrades the mechanical properties, like strength, wear resistance, and hardness of cold work tool steel parts. Thus, to control the mechanical properties, quantitative measurement of the retained austenite is a critical step in optimizing the heat-treating parameters. X-ray diffraction method is the most frequently used technique for this purpose. This technique is, however, destructive and time consuming. Furthermore, it is not applicable to 100% quality inspection of industrial parts. In the present paper, the influence of austenitizing temperature on the retained austenite content and hardness of AISI D2 tool steel has been studied. Additionally, nondestructive magnetic hysteresis parameters of the samples including coercivity, magnetic saturation, and maximum differential permeability as well as their magnetic Barkhausen noise features (RMS peak voltage and peak position) have been investigated. The results revealed direct relations between magnetic saturation, differential permeability, and MBN peak amplitude with increasing austenitizing temperature due to the retained austenite formation. Besides, both parameters of coercivity and peak position had an inverse correlation with the retained austenite fraction.

  10. Microstructure and mechanical properties of heat-resistant 12% Cr ferritic-martensitic steel EK-181 after thermomechanical treatment

    NASA Astrophysics Data System (ADS)

    Polekhina, N. A.; Litovchenko, I. Yu.; Tyumentsev, A. N.; Astafurova, E. G.; Chernov, V. M.; Leontyeva-Smirnova, M. V.

    2015-10-01

    The effect of high-temperature thermomechanical treatment (TMT) with the deformation in the austenitic region on the features of microstructure, phase transformations and mechanical properties of low-activation 12% Cr ferritic-martensitic steel EK-181 is investigated. It is established, that directly after thermomechanical treatment (without tempering) the sizes and density of V(CN) particles are comparable with those after a traditional heat treatment (air quenching and tempering at 720°C, 3 h), where these particles are formed only during tempering. It causes the increasing of the yield strength of the steel up to ≈1450 MPa at room temperature and up to ≈430 MPa at the test temperature T = 650°C. The potential of microstructure modification by this treatment aimed at improving heat resistance of steel is discussed.

  11. Applications of resistive heating in gas chromatography: a review.

    PubMed

    Jacobs, Matthew R; Hilder, Emily F; Shellie, Robert A

    2013-11-25

    Gas chromatography is widely applied to separate, identify, and quantify components of samples in a timely manner. Increasing demand for analytical throughput, instrument portability, environmental sustainability, and more economical analysis necessitates the development of new gas chromatography instrumentation. The applications of resistive column heating technologies have been espoused for nearly thirty years and resistively heated gas chromatography has been commercially available for the last ten years. Despite this lengthy period of existence, resistively heated gas chromatography has not been universally adopted. This low rate of adoption may be partially ascribed to the saturation of the market with older convection oven technology, coupled with other analytical challenges such as sampling, injection, detection and data processing occupying research. This article assesses the advantages and applications of resistive heating in gas chromatography and discusses practical considerations associated with adoption of this technology. PMID:24216193

  12. Effect of flow twisting on hydraulic resistance and heat exchange

    NASA Astrophysics Data System (ADS)

    Suslov, V. Ya.; Makarov, N. A.

    1989-02-01

    On the basis of dimensional analysis through a differentiated approach to the dimensions of length we have obtained formulas for the effect of flow twisting in a circular tube on the hydraulic resistance and exchange of heat.

  13. Vapor-Resistant Heat-Pipe Artery

    NASA Technical Reports Server (NTRS)

    Dussinger, Peter M.; Shaubach, Robert M.; Buchko, Matt

    1991-01-01

    Vapor lock in heat pipe delayed or prevented. Modifications of wick prevent flow of vapor into, or formation of vapor in, liquid-return artery. Small pores of fine-grained sintered wick help to prevent formation of large bubbles. Slotted tube offers few nucleation sites for bubbles. Improves return of liquid in heat pipe.

  14. In-vitro long term and electrochemical corrosion resistance of cold deformed nitrogen containing austenitic stainless steels in simulated body fluid.

    PubMed

    Talha, Mohd; Behera, C K; Sinha, O P

    2014-07-01

    This work was focused on the evaluation of the corrosion behavior of deformed (10% and 20% cold work) and annealed (at 1050 °C for 15 min followed by water quenching) Ni-free high nitrogen austenitic stainless steels (HNSs) in simulated body fluid at 37°C using weight loss method (long term), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Scanning electron microscopy (SEM) was used to understand the surface morphology of the alloys after polarization test. It has been observed that cold working had a significant influence on the corrosion resistant properties of these alloys. The weight loss and corrosion rates were observed to decrease with increasing degree of cold working and nitrogen content in the alloy. The corrosion resistance of the material is directly related to the resistance of the passive oxide film formed on its surface which was enhanced with cold working and nitrogen content. It was also observed that corrosion current densities were decreased and corrosion potentials were shifted to more positive values. By seeing pit morphology under SEM, shallower and smaller pits were associated with HNSs and cold worked samples, indicating that corrosion resistance increases with increasing nitrogen content and degree of cold deformation. X-ray diffraction profiles of annealed as well as deformed alloys were revealed and there is no evidence for formation of martensite or any other secondary phases. PMID:24857514

  15. Heat- And Oxidation-Resistant Electrodes

    NASA Technical Reports Server (NTRS)

    Schroeder, James E.

    1990-01-01

    Alloys coated with electrically conductive ceramics used to make strong, oxidation-resistant electrodes for electrochemical cells operating at temperatures of 1,000 to 1,300 degrees C. Fe3Al or Ni3Al coated with strontium-doped lanthanum manganite more resistant to chemical attack than all-metal electrode, less brittle than all-ceramic electrode, and less costly than either alternative.

  16. Sporulation, Heat Resistance, and Biological Properties of Clostridium perfringens

    PubMed Central

    Nishida, S.; Seo, N.; Nakagawa, M.

    1969-01-01

    A sporulation medium for 134 Clostridium perfringens strains, including types A, B, C, D, E, and F, was devised according to Grelet's observation that sporulation occurred when cultural environment became limited in any nutritional requirement indispensable for the growth of the organism. Sporulation took place most prominently when 10% cooked-meat broth (pH 7.2) containing 3% Proteose Peptone and 1% glucose was used for the preculture and 2% Poli Peptone medium (pH 7.8) was used for the subculture medium. Sometimes, terminal spores could be observed. A correlation between sporulation and heat resistance was examined by use of C. perfringens strains isolated from samples heated at different temperatures. Almost all strains isolated from unheated samples and from those heated at lower temperatures gave rise to spores in our sporulation medium, but the spores were weakly heat-resistant, whereas strains isolated from samples heated at 100 C for 60 min were highly heat-resistant but sporulated poorly. A majority of these heat-resistant strains were non-gelatinolytic and definitely salicin-fermenting. Images PMID:4304763

  17. Bonding Heat-Resistant Fabric to Tile

    NASA Technical Reports Server (NTRS)

    Holt, J. W.; Smiser, L. W.

    1985-01-01

    Acid etching, densification, and silica cement ensure strong bond. Key step in preparation for bonding to glazed tile is etching quartz fabric and tile with acid. This increases adhesion of silica cement used to form bond. Procedures use high-temperature materials exclusively and therefore suitable for securing flexible seals and heat barriers around doors and viewing ports in furnaces and kilns.

  18. Kinetics of isochronal austenization in modified high Cr ferritic heat-resistant steel

    NASA Astrophysics Data System (ADS)

    Liu, Chenxi; Liu, Yongchang; Zhang, Dantian; Yan, Zesheng

    2011-12-01

    Employment of high Cr ferritic steels as a main structural material is considered as a way to achieve economical competitiveness of main steam pipe and nuclear reactors in power plants. Differential dilatometry and microstructure observation were employed to investigate the isochronal austenitic transformation of the modified high Cr ferritic steel. The kinetics of the isochronal austenitic transformation were described by a phase-transformation model involving site saturation (pre-existing nuclei), diffusion-controlled growth, and incorporating an impingement correction. The experimental results and kinetic analysis indicate that an increase of the heating rate promotes the diffusion-controlled austenitic transformation. The dissolving degree of precipitates during the austenization process affects the activation energy for diffusion and the undissolved precipitates lead to an increase of the onset temperature of the subsequent martensite transformation upon cooling.

  19. Heat resistance of Yersinia enterocolitica grown at different temperatures and heated in different media.

    PubMed

    Pagán, R; Mañas, P; Raso, J; Trepat, F J

    1999-03-01

    In the range of 4-20 degrees C, growth temperature did not influence the heat resistance at 54-66 degrees C for Yersinia enterocolitica at pH 7 in citrate phosphate buffer. However, when cells were grown at 37 degrees C. the D62 increased from 0.044 to 0.17 min. This increase was constant at all heating temperatures tested (z = 5.7-5.8). Growth temperature did not influence the proportion of heat-damaged cells after a heat treatment, as measured by their response to a 2% of sodium chloride added to the recovery medium. The sensitivity of heat treated cells to nisin or lysozyme depended on growth temperature: Whereas the number of cells grown at 4 degrees C surviving heat treatment was the same regardless of the presence of 100 IU/ml of nisin or 100 microg/ml of lysozyme in the recovery medium, that of cells grown at 37 degrees C was, in these media, lower. The pH of maximum heat resistance in citrate phosphate buffer was pH 7 for cells grown at 37 degrees C, but pH 5 for those grown at 4 degrees C. In both suspensions the magnitude of the effect of pH on heat resistance was constant at all heating temperatures. For cells grown at 4 degrees C the heat resistance at 54-66 degrees C, in skimmed milk or pH 7 buffer, was the same. For cells grown at 37 degrees C this also applied for heat treatment at 66 degrees C but at 56 degrees C the heat resistance in skimmed milk was higher. PMID:10357274

  20. Heat resistant polymers of oxidized styrylphosphine

    NASA Technical Reports Server (NTRS)

    Paciorek, K. J. L. (Inventor)

    1978-01-01

    Homopolymers, copolymers and terpolymers of a styrene based monomer are prepared by polymerizing at least one oxidized styrylphosphine monomer or by polymerizing p-diphenylphosphinestyrene and then oxidizing the polymerized monomer with an organoazide. Copolymers can also be prepared by copolymerizing styrene with at least one oxidized styrylphosphine monomer. Flame resistant vinyl based polymers whose degradation products are non toxic and non corrosive are obtained.

  1. Parallel resistivity and ohmic heating of laboratory dipole plasmas

    SciTech Connect

    Fox, W.

    2012-08-15

    The parallel resistivity is calculated in the long-mean-free-path regime for the dipole plasma geometry; this is shown to be a neoclassical transport problem in the limit of a small number of circulating electrons. In this regime, the resistivity is substantially higher than the Spitzer resistivity due to the magnetic trapping of a majority of the electrons. This suggests that heating the outer flux surfaces of the plasma with low-frequency parallel electric fields can be substantially more efficient than might be naively estimated. Such a skin-current heating scheme is analyzed by deriving an equation for diffusion of skin currents into the plasma, from which quantities such as the resistive skin-depth, lumped-circuit impedance, and power deposited in the plasma can be estimated. Numerical estimates indicate that this may be a simple and efficient way to couple power into experiments in this geometry.

  2. Effect of mechanical surface and heat treatments on erosion resistance

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D. H.

    1981-01-01

    The effect of erosion by glass beads and crushed glass and by heat treatments on the erosional resistance of 6061 aluminum alloy and 1045 steel were studied. The aluminum alloy's erosion resistance was found to be insensitive to mechanical surface treatment applied before testing, and was determined to depend on the properties of the work-hardened surface layer; this was also demonstrated for aluminum alloy single crystals. The aluminum alloy heat treatments included annealing, solution, and precipitation. Solution was found to increase erosion resistance but precipitation had the opposite effect. Hardness showed no correlation with erosion resistance for either aluminum alloy steel. The steel tests showed that crushed glass provides an order of magnitude more erosion than glass beads.

  3. Influence of volumic heat treatments upon cavitation erosion resistance of duplex X2CrNiMoN 22-5-3 stainless steels

    NASA Astrophysics Data System (ADS)

    Micu, L. M.; Bordeasu, I.; Popoviciu, M. O.; Popescu, M.; Bordeaşu, D.; Salcianu, L. C.

    2015-06-01

    The stainless steels Duplex 2205 with austenite and ferrite structure have mechanical characteristics close to those of martensite stainless steels but a better corrosion resistance; these steels are very sensitive on the heat treatments. Present work studies the cavitation erosion for those steels for three different heat treatments: simply quenched, annealed at 475°C post quenching and annealed at 875°C. The researches were undertaken at Timisoara “Politehnica” University in the Laboratory of Material Science and the Laboratory of Cavitation, using the T2 facility which integrally respects the recommendation of ASTM G32- 10 Standard. The best results were obtained with the specimens annealed at 875°C. In comparison with the stainless steel 41Cr4, with very good cavitation erosion qualities, all tested steels presented also good erosion resistance. So, Duplex 2205 steels can be used for details subjected to cavitation. The best results are obtained by increasing both the hardness and the quantity of the structure constituent with better cavitation erosion resistance, in our case the alloyed austenite.

  4. Protoplast dehydration correlated with heat resistance of bacterial spores.

    PubMed Central

    Nakashio, S; Gerhardt, P

    1985-01-01

    Water content of the protoplast in situ within the fully hydrated dormant bacterial spore was quantified by use of a spore in which the complex of coat and outer (pericortex) membrane was genetically defective or chemically removed, as evidenced by susceptibility of the cortex to lysozyme and by permeability of the periprotoplast integument to glucose. Water content was determined by equilibrium permeability measurement with 3H-labeled water (confirmed by gravimetric measurement) for the entire spore, with 14C-labeled glucose for the integument outside the inner (pericytoplasm) membrane, and by the difference for the protoplast. The method was applied to lysozyme-sensitive spores of Bacillus stearothermophilus, B. subtilis, B. cereus, B. thuringiensis, and B. megaterium (four types). Comparable lysozyme-resistant spores, in which the outer membrane functioned as the primary permeability barrier to glucose, were employed as controls. Heat resistances were expressed as D100 values. Protoplast water content of the lysozyme-sensitive spore types correlated with heat resistance exponentially in two distinct clusters, with the four B. megaterium types in one alignment, and with the four other species types in another. Protoplast water contents of the B. megaterium spore types were sufficiently low (26 to 29%, based on wet protoplast weight) to account almost entirely for their lesser heat resistance. Corresponding values of the other species types were similar or higher (30 to 55%), indicating that these spores depended on factors additional to protoplast dehydration for their much greater heat resistance. PMID:3988704

  5. Fullerenes synthesis by combined resistive heating and arc discharge techniques.

    PubMed

    Kyesmen, Pannan Isa; Onoja, Audu; Amah, Alexander Nwabueze

    2016-01-01

    The two main electrode techniques for fullerenes production; the direct arc technique and the resistive heating of graphite rod were employed in this work. One of the electrodes was resistively heated to high temperature and subjected to arc discharge along its length by the second graphite rod. Fullerenes solid were extracted from carbon soot samples collected from an installed arc discharge system using the solvent extraction method. The fullerenes solid obtained from carbon soot collected for 2 min of arc discharge run when one of the electrodes was resistively heated at different voltages all gave higher yields (maximum of 67 % higher, at 150 A arc current and 200 Torr chamber pressure) compared to when no resistive heating was carried out. Scanning electron microscopy and ultraviolet visible spectroscopy analysis carried out on all fullerenes solid indicated the presence of fullerenes. The enhancement of fullerenes production by combined resistive and direct arc techniques shows prospect for possible use at industrial level for large scale production. PMID:27563518

  6. Theory of heat transfer and hydraulic resistance of oil radiators

    NASA Technical Reports Server (NTRS)

    Mariamov, N B

    1942-01-01

    In the present report the coefficients of heat transfer and hydraulic resistance are theoretically obtained for the case of laminar flow of a heated viscous liquid in a narrow rectangular channel. The results obtained are applied to the computation of oil radiators, which to a first approximation may be considered as made up of a system of such channels. In conclusion, a comparison is given of the theoretical with the experimental results obtained from tests on airplane oil radiators.

  7. Performance of a Heating Block System Designed for Studying the Heat Resistance of Bacteria in Foods.

    PubMed

    Kou, Xiao-Xi; Li, Rui; Hou, Li-Xia; Huang, Zhi; Ling, Bo; Wang, Shao-Jin

    2016-01-01

    Knowledge of bacteria's heat resistance is essential for developing effective thermal treatments. Choosing an appropriate test method is important to accurately determine bacteria's heat resistances. Although being a major factor to influence the thermo-tolerance of bacteria, the heating rate in samples cannot be controlled in water or oil bath methods due to main dependence on sample's thermal properties. A heating block system (HBS) was designed to regulate the heating rates in liquid, semi-solid and solid foods using a temperature controller. Distilled water, apple juice, mashed potato, almond powder and beef were selected to evaluate the HBS's performance by experiment and computer simulation. The results showed that the heating rates of 1, 5 and 10 °C/min with final set-point temperatures and holding times could be easily and precisely achieved in five selected food materials. A good agreement in sample central temperature profiles was obtained under various heating rates between experiment and simulation. The experimental and simulated results showed that the HBS could provide a sufficiently uniform heating environment in food samples. The effect of heating rate on bacterial thermal resistance was evaluated with the HBS. The system may hold potential applications for rapid and accurate assessments of bacteria's thermo-tolerances. PMID:27465120

  8. Performance of a Heating Block System Designed for Studying the Heat Resistance of Bacteria in Foods

    NASA Astrophysics Data System (ADS)

    Kou, Xiao-Xi; Li, Rui; Hou, Li-Xia; Huang, Zhi; Ling, Bo; Wang, Shao-Jin

    2016-07-01

    Knowledge of bacteria’s heat resistance is essential for developing effective thermal treatments. Choosing an appropriate test method is important to accurately determine bacteria’s heat resistances. Although being a major factor to influence the thermo-tolerance of bacteria, the heating rate in samples cannot be controlled in water or oil bath methods due to main dependence on sample’s thermal properties. A heating block system (HBS) was designed to regulate the heating rates in liquid, semi-solid and solid foods using a temperature controller. Distilled water, apple juice, mashed potato, almond powder and beef were selected to evaluate the HBS’s performance by experiment and computer simulation. The results showed that the heating rates of 1, 5 and 10 °C/min with final set-point temperatures and holding times could be easily and precisely achieved in five selected food materials. A good agreement in sample central temperature profiles was obtained under various heating rates between experiment and simulation. The experimental and simulated results showed that the HBS could provide a sufficiently uniform heating environment in food samples. The effect of heating rate on bacterial thermal resistance was evaluated with the HBS. The system may hold potential applications for rapid and accurate assessments of bacteria’s thermo-tolerances.

  9. Performance of a Heating Block System Designed for Studying the Heat Resistance of Bacteria in Foods

    PubMed Central

    Kou, Xiao-xi; Li, Rui; Hou, Li-xia; Huang, Zhi; Ling, Bo; Wang, Shao-jin

    2016-01-01

    Knowledge of bacteria’s heat resistance is essential for developing effective thermal treatments. Choosing an appropriate test method is important to accurately determine bacteria’s heat resistances. Although being a major factor to influence the thermo-tolerance of bacteria, the heating rate in samples cannot be controlled in water or oil bath methods due to main dependence on sample’s thermal properties. A heating block system (HBS) was designed to regulate the heating rates in liquid, semi-solid and solid foods using a temperature controller. Distilled water, apple juice, mashed potato, almond powder and beef were selected to evaluate the HBS’s performance by experiment and computer simulation. The results showed that the heating rates of 1, 5 and 10 °C/min with final set-point temperatures and holding times could be easily and precisely achieved in five selected food materials. A good agreement in sample central temperature profiles was obtained under various heating rates between experiment and simulation. The experimental and simulated results showed that the HBS could provide a sufficiently uniform heating environment in food samples. The effect of heating rate on bacterial thermal resistance was evaluated with the HBS. The system may hold potential applications for rapid and accurate assessments of bacteria’s thermo-tolerances. PMID:27465120

  10. Evaluation of Heat Checking and Washout of Heat Resistant Superalloys and Coatings for Die inserts

    SciTech Connect

    David Schwam; John F. Wallace; Yulong Zhu; Edward Courtright; Harold Adkins

    2005-01-30

    This project had two main objectives: (1) To design, fabricate and run a full size test for evaluating soldering and washout in die insert materials. This test utilizes the unique capabilities of the 350 Ton Squeeze Casting machine available in the Case Meal Casting Laboratory. Apply the test to evaluate resistance of die materials and coating, including heat resistant alloys to soldering and washout damage. (2) To evaluate materials and coatings, including heat resistant superalloys, for use as inserts in die casting of aluminum alloys.

  11. Heat resistant polymers of oxidized styrylphosphine

    NASA Technical Reports Server (NTRS)

    Paciorek, K. J. L. (Inventor)

    1980-01-01

    A flame resistant, nontoxic polymer which may be used safely in confined locations where there is inadequate ventilation is prepared either by polymerizing compounds having the formula R-N=P(C6H5)2(C6H4)CH=CH2 where R is an organic moeity selected from the group of (C6H5)2P(O)-, (C6H5O)2P(O)-, (C6H5)2 C3N3-, or their mixtures, or by reacting a polymer with an organic azide such as diphenylphosphinylazide, diphenyl-phosphorylazide, 2-azido-4,6-diphenly-5-triazine, 2,4-diazido-6-phenyl-s-triazine, trimethylsilyoazide, triphenylsilylazine, and phenylazine. The reaction of the styrylphosphine with the organozaide results in the oxidation of the trivalent phosphorus atom to the pentavalent state in the form of an unsaturated P=N linkage known as a phosphazene group.

  12. Alumina-Forming Austenitics: A New Approach to Thermal and Degradation Resistant Stainless Steels for Industrial Use

    SciTech Connect

    David A Helmick; John H Magee; Michael P Brady

    2012-05-31

    A series of developmental AFA alloys was selected for study based on: 25 Ni wt.% (alloys A-F), 20 wt% Ni (alloys G-H), and 12 Ni wt.% (alloys I-L). An emphasis in this work was placed on the lower alloy content direction for AFA alloys to reduce alloy raw material cost, rather than more highly alloyed and costly AFA alloys for higher temperature performance. Alloys A-D explored the effects of Al (3-4 wt.%) and C (0.05-0.2 wt.%) in the Fe-25Ni-14Cr-2Mn-2Mo-1W-1Nb wt.% base range; alloys E and F explored the effects of removing costly Mo and W additions in a Fe-25Ni-14Cr-4Al-2.5Nb-2Mn-0.2C base, alloys G and H examined Nb (1-2.5wt.%) and removal of Mo, W in a Fe-20Ni-14Cr-3Al-2Mn-0.2 C wt.% base; and alloys I-L examined effects of C (0.1-0.2 wt.%) and Mn (5-10 wt.%) on a low cost Fe-14Cr-12Ni-3Cu-2.5Al wt.% base (no Mo, W additions). Creep testing resulted in elemental trends that included the beneficial effect of higher carbon and lower niobium in 20-25%Ni AFA alloys and, the beneficial of lower Mn in 12%Ni AFA alloys. Corrosion tests in steam and sulfidation-oxidation environments showed, in general, these alloys were capable of a ten-fold improvement in performance when compared to conventional austenitic stainless steels. Also, corrosion test results in metal-dusting environments were promising and, warrant further investigation.

  13. Effects of heat treatment on wear resistance and fracture toughness of duo-cast materials composed of high-chromium white cast iron and low-chromium steel

    NASA Astrophysics Data System (ADS)

    Kim, Chang Kyu; Lee, Sunghak; Jung, Jae-Young

    2006-03-01

    The objective of this study is to investigate effects of heat treatment on wear resistance and fracture toughness in duo-cast materials composed of a high-chromium white cast iron and a low-chromium steel as a wear-resistant part and a ductile part, respectively. Different size, volume fraction, and distribution of M7C3 carbides were employed in the wear-resistant part by changing the amount of chromium, and the volume fraction of martensite in the austenitic matrix was varied by the heat treatment. In the alloys containing a small amount of chromium, an interdendritic structure of eutectic M7C3 carbides was formed, and led to the improvement of wear resistance and fracture toughness. After the heat treatment, the selective wear of the matrix and the cracking or spalled-off carbides were considerably reduced since the hardness difference between carbides and matrix decreased by the increase in the matrix hardness, thereby leading to the improvement of the wear resistance. However, the fracture toughness of the heat-treated alloys was lower than that of the as-cast alloys because the matrix containing a considerable amount of martensite did not effectively prevent the crack propagation.

  14. Hot deformation of heat-resistant superalloys -- An overview

    SciTech Connect

    Chaudhury, P.K.; Zhao, D.; Thirukkonda, M.; Guillard, S.

    1995-12-31

    The hot deformation behavior was investigated for four heat-resistant Ni-, Fe-, and Co-base superalloys: Haynes 188, 230, 556, and HR-160. Compression tests were conducted over a wide range of processing conditions. The flow behavior and deformed microstructures were characterized, while recrystallized grain size and percentage of recrystallization were measured for deformed specimens under selected conditions. From the experimental data, constitutive equations and microstructure maps were constructed. During the high temperature deformation, a number of mutually interacting metallurgical processes, such as dynamic recrystallization and precipitation, occurred. Their influence on hot formability and deformed microstructure have been represented by deformation microstructure maps that can serve as a guideline for hot deformation process design and subsequent heat treatment after hot forming. The workability and deformation behaviors of the heat-resistant alloys are also compared in The light of alloy development to ensure the fabricability of newly developed alloys.

  15. Testing Method for Heat Resistance Under Temperature Gradient

    NASA Astrophysics Data System (ADS)

    Takagi, K.; Kawasaki, A.; Itoh, Y.; Harada, Y.; Ono, F.

    2007-12-01

    “Testing Method for Heat Resistance under Temperature Gradient” is a Japanese Industrial Standard (JIS) newly established by the Minister of Economy, Trade and Industry, after deliberations by the Japanese Industrial Standards Committee, in accordance with the Industrial Standardization Law. This standard specified the testing method for heat resistance under temperature gradient of materials and coated members of equipment exposed to high temperature, such as aircraft engines, gas turbines, and so on. This paper introduces the principle and overview of the established standard. In addition, taking the heat cycle test using the burner rig for instance, we specifically illustrate the acquirable data and their analysis in the standard. Monitoring of the effective thermal conductivity and acoustic emission particularly enables to the non-destructive evaluation of failure cycle.

  16. Heat Shock-Independent Induction of Multidrug Resistance by Heat Shock Factor 1†

    PubMed Central

    Tchénio, Thierry; Havard, Marilyne; Martinez, Luis A.; Dautry, François

    2006-01-01

    The screening of two different retroviral cDNA expression libraries to select genes that confer constitutive doxorubicin resistance has in both cases resulted in the isolation of the heat shock factor 1 (HSF1) transcription factor. We show that HSF1 induces a multidrug resistance phenotype that occurs in the absence of heat shock or cellular stress and is mediated at least in part through the constitutive activation of the multidrug resistance gene 1 (MDR-1). This drug resistance phenotype does not correlate with an increased expression of heat shock-responsive genes (heat shock protein genes, or HSPs). In addition, HSF1 mutants lacking HSP gene activation are also capable of conferring multidrug resistance, and only hypophosphorylated HSF1 complexes accumulate in transduced cells. Our results indicate that HSF1 can activate MDR-1 expression in a stress-independent manner that differs from the canonical heat shock-activated mechanism involved in HSP induction. We further provide evidence that the induction of MDR-1 expression occurs at a posttranscriptional level, revealing a novel undocumented role for hypophosphorylated HSF1 in posttranscriptional gene regulation. PMID:16382149

  17. Effect of mechanical surface and heat treatments on erosion resistance

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D. H.

    1980-01-01

    The effects of mechanical surface treatments as well as heat treatments on the erosion resistance of 6061 aluminum alloy and 1045 steel were studied. Mechanical surface treatments were found to have little or no effect on the erosion resistance. This is due to the formation by particle impact of a work hardened surface layer regardless of the initial surface condition. The erosion resistance of Al single crystals is found to be independent of orientation. This is due to destruction of the surface microstructure and formation of a polycrystalline surface layer by the impact of erodant particles as observed by X-ray diffraction. While upon solution treatment of annealed 6061 aluminum the increase in hardness is accompanied by an increase in erosion resistance, precipitation treatment which causes a further increase in hardness results in slightly lower erosion resistance. Using two types of erodant particles, glass beads and crushed glass, the erosion rate is found to be strongly dependent on erodant particle shape, being an order of magnitude higher for erosion with crushed glass as compared to glass beads. While for erosion with glass beads heat treatment of 1045 steel had a profound effect on its erosion resistance, little or no such effect was observed for erosion with crushed glass.

  18. Effect of Welding Current and Time on the Microstructure, Mechanical Characterizations, and Fracture Studies of Resistance Spot Welding Joints of AISI 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kianersi, Danial; Mostafaei, Amir; Mohammadi, Javad

    2014-09-01

    This article aims at investigating the effect of welding parameters, namely, welding current and welding time, on resistance spot welding (RSW) of the AISI 316L austenitic stainless steel sheets. The influence of welding current and welding time on the weld properties including the weld nugget diameter or fusion zone, tensile-shear load-bearing capacity of welded materials, failure modes, energy absorption, and microstructure of welded nuggets was precisely considered. Microstructural studies and mechanical properties showed that the region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. Electron microscopic studies indicated different types of delta ferrite in welded nuggets including skeletal, acicular, and lathy delta ferrite morphologies as a result of nonequilibrium phases, which can be attributed to a fast cooling rate in the RSW process. These morphologies were explained based on Shaeffler, WRC-1992, and pseudo-binary phase diagrams. The optimum microstructure and mechanical properties were achieved with 8-kA welding current and 4-cycle welding time in which maximum tensile-shear load-bearing capacity or peak load of the welded materials was obtained at 8070 N, and the failure mode took place as button pullout with tearing from the base metal. Finally, fracture surface studies indicated that elongated dimples appeared on the surface as a result of ductile fracture in the sample welded in the optimum welding condition.

  19. SIGNAL MEDIATORS AT INDUCTION OF HEAT RESISTANCE OF WHEAT PLANTLETS BY SHORT-TERM HEATING.

    PubMed

    Karpets, Yu V; Kolupaev, Yu E; Yastreb, T O

    2015-01-01

    The effects of functional interplay of calcium ions, reactive oxygen species (ROS) and nitric oxide (NO) in the cells of wheat plantlets roots (Triticum aestivum L.) at the induction of their heat resistance by a short-term influence of hyperthermia (heating at the temperature of 42 degrees C during 1 minute) have been investigated. The transitional increase of NO and H2O2 content, invoked by heating, was suppressed by the treatment of plantlets with the antagonists of calcium EGTA (chelator of exocellular calcium), lanthanum chloride (blocker of calcium channels of various types) and neomycin (inhibitor of phosphatidylinositol-dependent phospholipase C). The rise of hydrogen peroxide content, caused by hardening, was partially suppressed by the action of inhibitors of nitrate reductase (sodium wolframate) and NO-synthase (N(G)-nitro-L-arginine methyl ester--L-NAME), and the increasing of nitric oxide content was suppressed by the treatment of plants with the antioxidant ionol and with the scavenger of hydrogen peroxide (dimethylthiourea). These compounds and antagonists of calcium also partially removed the effect of the rise of plantlets' heat resistance, invoked by hardening heating. The conclusion on calcium's role in the activation of enzymatic systems, generating reactive oxygen species and nitric oxide, and on the functional interplay of these signal mediators at the induction of heat resistance of plantlets by hardening heating is made. PMID:27025064

  20. Replacing Resistance Heating with Mini-Split Heat Pumps, Sharon, Connecticut (Fact Sheet)

    SciTech Connect

    Not Available

    2014-05-01

    Mini-split heat pumps can provide space heating and cooling in many climates and are relatively affordable. These and other features make them potentially suitable for retrofitting into multifamily buildings in cold climates to replace electric resistance heating or other outmoded heating systems. This report investigates the suitability of mini-split heat pumps for multifamily retrofits. Various technical and regulatory barriers are discussed and modeling was performed to compare long-term costs of substituting mini-splits for a variety of other heating and cooling options. A number of utility programs have retrofit mini-splits in both single family and multifamily residences. Two such multifamily programs are discussed in detail.

  1. Leather Coated with Mixtures of Humectant and Antioxidants to Improve UV and Heat Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultraviolet (UV) and heat resistance are very important qualities for leather products. We recently developed an environmentally friendly finishing process for improving the UV- and heat resistance of automobile upholstery leather. We previously reported and demonstrated some promising results fro...

  2. Development of a high strength, hydrogen-resistant austenitic alloy. [Fe-36 Ni-3 Ti-3 Ta-1. 3 Mo

    SciTech Connect

    Chang, K.M.; Klahn, D.H.; Morris, J.W. Jr.

    1980-08-01

    Research toward high-strength, high toughness nonmagnetic steels for use in the retaining rings of large electrical generators led to the development of a Ta-modified iron-based superalloy (Fe-36 Ni-3 Ti-3 Ta-0.5 Al-1.3 Mo-0.3 V-0.01 B) which combines high strength with good toughness after suitable aging. The alloy did, however, show some degradation in fatigue resistance in gaseous hydrogen. This sensitivity was associated with a deformation-induced martensitic transformation near the fracture surface. The addition of a small amount of chromium to the alloy suppressed the martensite transformation and led to a marked improvement in hydrogen resistance.

  3. Diesel particulate filter regeneration via resistive surface heating

    DOEpatents

    Gonze, Eugene V; Ament, Frank

    2013-10-08

    An exhaust system that processes exhaust generated by an engine is provided. The system includes: a particulate filter (PF) that filters particulates from the exhaust wherein an upstream end of the PF receives exhaust from the engine; and a grid of electrically resistive material that is applied to an exterior upstream surface of the PF and that selectively heats exhaust passing through the grid to initiate combustion of particulates within the PF.

  4. Austenitic structure formation in an Fe-32% Ni alloy during slow heating in the critical temperature range

    NASA Astrophysics Data System (ADS)

    Zemtsova, N. D.

    2014-08-01

    Electron diffraction is used to show (for the first time) that the reverse α → γ transformation in an Fe-32% Ni during slow heating develops via the formation of an intermediate paramagnetic 9 R phase. Coarse extended lamellae form according to a shear mechanism in the central part of the temperature range of the reverse transformation, which is called the critical range (here, the physical properties of the alloy change anomalously). The extended lamellae consist of 9 R-phase lamellae with γ-phase interlayers. A high density of periodic stacking faults in the structure of the 9 R phase and a high density of chaotic stacking faults in the complex 9 R + γ phase determine the nature of phase transformation-induced hardening.

  5. Steerable Catheter Microcoils for Interventional MRI: Reducing Resistive Heating

    PubMed Central

    Bernhardt, Anthony; Wilson, Mark W.; Settecase, Fabio; Evans, Leland; Malba, Vincent; Martin, Alastair J.; Saeed, Maythem; Roberts, Timothy P. L.; Arenson, Ronald L.; Hetts, Steven W.

    2010-01-01

    PURPOSE To assess resistive heating of microwires used for remote catheter steering in interventional magnetic resonance imaging. To investigate the use of alumina to facilitate heat transfer to saline flowing in the catheter lumen. MATERIALS AND METHODS A microcoil was fabricated using a laser lathe onto polyimide-tipped or alumina-tipped endovascular catheters. In vitro testing was performed in a 1.5 T MR system using a vessel phantom, body RF coil, and steady state pulse sequence. Resistive heating was measured with water flowing over a polyimide tip catheter, or saline flowing through the lumen of an alumina-tip catheter. Preliminary in vivo testing in porcine common carotid arteries was conducted with normal blood flow or after arterial ligation when current was applied to an alumnia-tip catheter for up to 5 minutes. RESULTS After application of up to 1 W of DC power, clinically significant temperature increases were noted with the polyimide-tip catheter: 23°C/W at zero flow, 13°C/W at 0.28 cc/s, and 7.9°C/W at 1 cc/s. Using the alumina-tip catheter, the effluent temperature rise using the lowest flow rate (0.12 cc/s) was 2.3°C/W. In vivo testing demonstrated no thermal injury to vessel walls at normal and zero arterial flow. CONCLUSION Resistive heating in current carrying wire pairs can be dissipated by saline coolant flowing within the lumen of a catheter tip composed of material that facilitates heat transfer. PMID:21075017

  6. Studies of Resistive Wall Heating at JLAB FEL

    SciTech Connect

    Li, Rui; Benson, Stephen V.

    2013-06-01

    When the JLAB FEL is under CW operation, it had been observed that temperature rises over the wiggler vacuum chamber, presumably as the result of the power deposition on the resistive wall of the wiggler chamber. Previous analyses have been done on the resistive wall impedance for various cases, such as DC, AC, and anomalous skin effects*. Here we report an investigation on the beam kinetic energy losses for each of these cases. This study includes the non-ultrarelativistic effect on resistive wall loss, for both round pipe and parallel plates. We will present the comparison of our results with the measured data obtained during CW operation of the JLAB FEL. Other possible factors contributing to the measured heating will also be discussed.

  7. Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint

    NASA Astrophysics Data System (ADS)

    Rahmani, Mehdi; Eghlimi, Abbas; Shamanian, Morteza

    2014-10-01

    To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.

  8. Nanostructured nickel-free austenitic stainless steel/hydroxyapatite composites.

    PubMed

    Tulinski, Maciej; Jurczyk, Mieczyslaw

    2012-11-01

    In this work Ni-free austenitic stainless steels with nanostructure and their nanocomposites with hydroxyapatite are presented and characterized by means of X-ray diffraction and optical profiling. The samples were synthesized by mechanical alloying, heat treatment and nitriding of elemental microcrystalline powders with addition of hydroxyapatite (HA). In our work we wanted to introduce into stainless steel hydroxyapatite ceramics that have been intensively studied for bone repair and replacement applications. Such applications were chosen because of their high biocompatibility and ability to bond to bone. Since nickel-free austenitic stainless steels seem to have better mechanical properties, corrosion resistance and biocompatibility compared to 316L stainless steels, it is possible that composite made of this steel and HA could improve properties, as well. Mechanical alloying and nitriding are very effective technologies to improve the corrosion resistance of stainless steel. Similar process in case of nanocomposites of stainless steel with hydroxyapatite helps achieve even better mechanical properties and corrosion resistance. Hence nanocrystalline nickel-free stainless steels and nickel-free stainless steel/hydroxyapatite nanocomposites could be promising bionanomaterials for use as a hard tissue replacement implants, e.g., orthopedic implants. In such application, the surface roughness and more specifically the surface topography influences the proliferation of cells (e.g., osteoblasts). PMID:23421285

  9. Evaluation of Alumina-Forming Austenitic Foil for Advanced Recuperators

    SciTech Connect

    Pint, Bruce A; Brady, Michael P; Yamamoto, Yukinori; Santella, Michael L; Maziasz, Philip J; Matthews, Wendy

    2011-01-01

    A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. By optimizing the Al and Cr contents, the alloy is fully austenitic for creep strength while allowing the formation of a chemically stable external alumina scale at temperatures up to 900 C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. As a first step in producing foil for primary surface recuperators, three commercially cast heats have been rolled to 100 m thick foil in the laboratory to evaluate performance in creep and oxidation testing. Results from initial creep testing are presented at 675 C and 750 C, showing excellent creep strength compared with other candidate foil materials. Laboratory exposures in humid air at 650 800 C have shown acceptable oxidation resistance. A similar oxidation behavior was observed for sheet specimens of these alloys exposed in a modified 65 kW microturbine for 2871 h. One composition that showed superior creep and oxidation resistance has been selected for the preparation of a commercial batch of foil. DOI: 10.1115/1.4002827

  10. Response of Two Heat Shock Genes to Selection for Knockdown Heat Resistance in Drosophila Melanogaster

    PubMed Central

    McColl, G.; Hoffmann, A. A.; McKechnie, S. W.

    1996-01-01

    To identify genes involved in stress resistance and heat hardening, replicate lines of Drosophila melanogaster were selected for increased resistance to knockdown by a 39° heat stress. Two selective regimes were used, one with and one without prior hardening. Mean knockdown times were increased from ~5 min to >20 min after 18 generations. Initial realized heritabilities were as high as 10% for lines selected without hardening, and crosses between lines indicated simple additive gene effects for the selected phenotypes. To survey allelic variation and correlated selection responses in two candidate stress genes, hsr-omega and hsp68, we applied denaturing gradient gel electrophoresis to amplified DNA sequences from small regions of these genes. After eight generations of selection, allele frequencies at both loci showed correlated responses for selection following hardening, but not without hardening. The hardening process itself was associated with a hsp68 frequency change in the opposite direction to that associated with selection that followed hardening. These stress loci are closely linked on chromosome III, and the hardening selection established a disequilibrium, suggesting an epistatic effect on resistance. The data indicate that molecular variation in both hsr-omega and hsp68 contribute to natural heritable variation for hardened heat resistance. PMID:8844150

  11. A resistively heated CeB{sub 6} emissive probe

    SciTech Connect

    Martin, M. J. Bonde, J.; Gekelman, W.; Pribyl, P.

    2015-05-15

    The plasma potential, V{sub p}, is a key quantity in experimental plasma physics. Its spatial gradients directly yield the electrostatic field present. Emissive probes operating under space-charge limited emission conditions float close to V{sub p} even under time-varying conditions. Throughout their long history in plasma physics, they have mostly been constructed with resistively heated tungsten wire filaments. In high density plasmas (>10{sup 12} cm{sup −3}), hexaboride emitters are required because tungsten filaments cannot be heated to sufficient emission without component failure. A resistively heated emissive probe with a cerium hexaboride, CeB{sub 6}, emitter has been developed to work in plasma densities up to 10{sup 13} cm{sup −3}. To show functionality, three spatial profiles of V{sub p} are compared using the emissive probe, a cold floating probe, and a swept probe inside a plasma containing regions with and without current. The swept probe and emissive probe agree well across the profile while the floating cold probe fails in the current carrying region.

  12. Effect of heating rate on highly heat-resistant spore-forming microorganisms.

    PubMed

    Gómez-Jódar, Isabel; Ros-Chumillas, María; Palop, Alfredo

    2016-03-01

    Highly heat-resistant spore-forming Bacillus cause nonsterility problems in canned food and reduce the shelf life of many processed foods. The aim of this research was to evaluate the thermal inactivation of Bacillus sporothermodurans IIC65, Bacillus subtilis IC9, and Geobacillus stearothermophilus T26 under isothermal and nonisothermal conditions. The data obtained showed that B. sporothermodurans and B. subtilis were more heat resistant than G. stearothermophilus. The survival curves of B. sporothermodurans and B. subtilis showed shoulders, while the survival curves of G. stearothermophilus showed tails. Under nonisothermal treatment, at heating rates of 1 and 20 ℃/min, time needed to completely inactivate G. stearothermophilus was shorter than that required for B. sporothermodurans and B. subtilis. In complex heat treatments (heating-holding-cooling), the survival curves of B. sporothermodurans and B. subtilis showed the same activation shoulders than those obtained under isothermal treatments and the activation shoulders were again absent in the case of G. stearothermophilus. Predictions fitted quite well the data obtained for B. sporothermodurans. In contrast, the data for B. subtilis showed half a log cycle more survival than expected and in the case of G. stearothermophilus, the survival curve obtained showed much higher inactivation than expected. PMID:25852134

  13. Mechanical properties and retained austenite in intercritically heat-treated bainite-transformed steel and their variation with Si and Mn additions

    NASA Astrophysics Data System (ADS)

    Sakuma, Yasuharu; Matsumura, Osamu; Takechi, Hiroshi

    1991-02-01

    Processing peculiarities and functions of alloying elements, such as Si and Mn, were studied for improving formability of steel sheets with mixed microstructures. Annealing a sheet steel with 0.2 pct C in the intercritical range produced very fine particles of retained austenite which were moderately stabilized due to C enrichment by subsequent holding in the bainite transformation range. Its strength-ductility balance is greatly superior to that of other dual-phase steels due to transformation-induced plasticity ( TRIP). The holding time in the bainite transformation range varies with temperature, depending on the activation energy of C diffusion in austenite, and shifts to longer times with an increase of Si or Mn additions. The optimum cooling rate from the intercritical region is reduced with an increase of Mn content but is not influenced by Si content. Additional Mn makes the retained austenite content larger, although uniform elongation remains the same. In this case, the product of tensile strength and total elongation is increased due to an increase in the tensile strength. Contrary to Mn, Si does not affect retained austenite content but improves the uniform elongation by increasing its stability.

  14. Heat sealable, flame and abrasion resistant coated fabric

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1983-01-01

    Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.

  15. Viability and heat resistance of murine norovirus on bread.

    PubMed

    Takahashi, Michiko; Takahashi, Hajime; Kuda, Takashi; Kimura, Bon

    2016-01-01

    Contaminated bread was the cause of a large-scale outbreak of norovirus disease in Japan in 2014. Contamination of seafood and uncooked food products by norovirus has been reported several times in the past; however the outbreak resulting from the contamination of bread products was unusual. A few reports on the presence of norovirus on bread products are available; however there have been no studies on the viability and heat resistance of norovirus on breads, which were investigated in this study. ce:italic>/ce:italic> strain 1 (MNV-1), a surrogate for human norovirus, was inoculated directly on 3 types of bread, but the infectivity of MNV-1 on bread samples was almost unchanged after 5days at 20°C. MNV-1 was inoculated on white bread that was subsequently heated in a toaster for a maximum of 2min. The results showed that MNV-1 remained viable if the heating period was insufficient to inactivate. In addition, bread dough contaminated with MNV-1 was baked in the oven. Our results indicated that MNV-1 may remain viable on breads if the heating duration or temperature is insufficient. PMID:26485672

  16. Effect of initial microstructure on austenite formation kinetics in high-strength experimental microalloyed steels

    NASA Astrophysics Data System (ADS)

    López-Martínez, Edgar; Vázquez-Gómez, Octavio; Vergara-Hernández, Héctor Javier; Campillo, Bernardo

    2015-12-01

    Austenite formation kinetics in two high-strength experimental microalloyed steels with different initial microstructures comprising bainite-martensite and ferrite-martensite/austenite microconstituents was studied during continuous heating by dilatometric analysis. Austenite formation occurred in two steps: (1) carbide dissolution and precipitation and (2) transformation of residual ferrite to austenite. Dilatometric analysis was used to determine the critical temperatures of austenite formation and continuous heating transformation diagrams for heating rates ranging from 0.03°C•s-1 to 0.67°C•s-1. The austenite volume fraction was fitted using the Johnson-Mehl-Avrami-Kolmogorov equation to determine the kinetic parameters k and n as functions of the heating rate. Both n and k parameters increased with increasing heating rate, which suggests an increase in the nucleation and growth rates of austenite. The activation energy of austenite formation was determined by the Kissinger method. Two activation energies were associated with each of the two austenite formation steps. In the first step, the austenite growth rate was controlled by carbon diffusion from carbide dissolution and precipitation; in the second step, it was controlled by the dissolution of residual ferrite to austenite.

  17. Influence of Heat Treatment on the Microstructure and Corrosion Resistance of 13 Wt Pct Cr-Type Martensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Lu, Si-Yuan; Yao, Ke-Fu; Chen, Yun-Bo; Wang, Miao-Hui; Ge, Xue-Yuan

    2015-12-01

    The effect of heat treatment on the microstructure and the electrochemical properties of a typical corrosion-resistant plastic mold steel in Cl--containing solution were studied in this research. Through X-ray diffraction patterns, SEM and TEM analysis, it was found that the sequence of the precipitates in the steels tempered at 573 K, 773 K, and 923 K (300 °C, 500 °C, and 650 °C) was θ-M3C carbides, nano-sized Cr-rich M23C6 carbides, and micro/submicron-sized Cr-rich M23C6 carbides, respectively. The results of the electrochemical experiments showed that the pitting potential of the as-quenched martensitic stainless steels increased with the austenitizing temperature. However, the corrosion resistance of the steels would decreased after tempering, especially when tempered at 773 K (500 °C), no passivation regime could be found in the polarization curve of the MSSs and no effective passive film could be formed on the steels in Cl--containing environments. The present results suggested that the temperature around 773 K (500 °C) should be avoided for tempering process of MSS used as plastic molds.

  18. Anomalous resistivity and heating in current-driven plasma thrusters

    NASA Astrophysics Data System (ADS)

    Choueiri, E. Y.

    1999-05-01

    A theory is presented of anomalous resistivity and particle heating in current-driven plasma accelerators such as the magnetoplasmadynamic thruster (MPDT). An electromagnetic dielectric tensor is used for a current-carrying, collisional and finite-beta plasma and it is found that an instability akin to the generalized lower hybrid drift instability (GLHDI) exists for electromagnetic modes (i.e., with finite polarization). Weak turbulence theory is then used to develop a second-order description of the heating rates of particles by the waves and the electron-wave momentum exchange rate that controls the anomalous resistivity effect. It is found that the electron Hall parameter strongly scales the level of anomalous dissipation for the case of the MPDT plasma. This scaling has recently been confirmed experimentally [Phys. Plasmas 5, 3581 (1997)]. Polynomial expressions of the relevant transport coefficients cast solely in terms of macroscopic parameters are also obtained for including microturbulence effects in numerical plasma fluid models used for thruster flow simulation.

  19. Self-healing of creep damage in heat resisting steels

    NASA Astrophysics Data System (ADS)

    Shinya, Norio; Kyono, Junro

    2002-07-01

    In heat resisting steels, micro holes, called creep cavities, are formed at grain boundaries by long term use at high temperatures. These creep cavities grow along grain boundaries, form grain boundary cracks by linking up each other anc cause low ductility and premature fracture as shown in Fig. 1. Therefore long term creep rupture strength and ductilities chiefly depend upon the behavior of nucleation and growth of creep cavities. If the growth of creep cavities could be suppressed, creep rupture strength and ductilities should be improved remarkably. Present work is intended to propose a self-healing process for the cavitation, and improve the creep rupture properties by the self-healing. It is thought that chemical compound of BN precipitates at inside surface of creep cavity by addition of B and N to heat resisting steels. As the BN is very stable at high temperatures, the precipitation of BN at creep cavity surface is expected to suppress the creep cavity growth and bring about the healing effect on the cavitation.

  20. An Investigation on Low-Temperature Thermochemical Treatments of Austenitic Stainless Steel in Fluidized Bed Furnace

    NASA Astrophysics Data System (ADS)

    Haruman, E.; Sun, Y.; Triwiyanto, A.; Manurung, Y. H. P.; Adesta, E. Y.

    2012-03-01

    In this study, the feasibility of using an industrial fluidized bed furnace to perform low-temperature thermochemical treatments of austenitic stainless steels has been studied, with the aim to produce expanded austenite layers with combined wear and corrosion resistance, similar to those achievable by plasma and gaseous processes. Several low-temperature thermochemical treatments were studied, including nitriding, carburizing, combined nitriding-carburizing (hybrid treatment), and sequential carburizing and nitriding. The results demonstrate that it is feasible to produce expanded austenite layers on the investigated austenitic stainless steel by the fluidized bed heat treatment technique, thus widening the application window for the novel low-temperature processes. The results also demonstrate that the fluidized bed furnace is the most effective for performing the hybrid treatment, which involves the simultaneous incorporation of nitrogen and carbon together into the surface region of the component in nitrogen- and carbon-containing atmospheres. Such hybrid treatment produces a thicker and harder layer than the other three processes investigated.

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. Transient heat-stress compromises the resistance of wheat seedlings to Hessian fly (Diptera: Cecidomyiidae) infestation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heat-stress exerts profound impact on resistance of plants to parasites. In this research, we investigated the impact of an acute, transient heat-stress on the resistance of the wheat line 'Molly', which contains the resistance gene H13, to an avirulent Hessian fly [Mayetiola destructor (Say)] popu...

  7. Formation Mechanism of Type IV Failure in High Cr Ferritic Heat-Resistant Steel-Welded Joint

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Tsukamoto, S.; Shirane, T.; Abe, F.

    2013-10-01

    The mechanism of type IV failure has been investigated by using a conventional 9Cr ferritic heat-resistant steel Gr.92. In order to clarify the main cause of type IV failure, different heat treatments were performed on the base metal in order to change the prior austenite grain (PAG) size and precipitate distribution after applying the heat-affected zone (HAZ) simulated thermal cycle at the peak temperature of around A c3 ( A c3 HAZ thermal cycle) and postweld heat treatment (PWHT). The microstructural evolution during the A c3 HAZ thermal cycle and PWHT was investigated by means of scanning electron microscope (SEM), electron backscatter diffraction (EBSD), electron probe microanalysis (EPMA), and transmission electron microscope (TEM). It was found that M23C6 carbides were scarcely precipitated at the newly formed fine PAG, block, and lath boundaries in A c3 HAZ-simulated Gr.92, because the carbide forming elements such as Cr and C were segregated at the former PAG and block boundaries of the base metal. On the other hand, if all the boundaries were covered by sufficient M23C6 carbides by homogenization of the alloying elements prior to applying the HAZ thermal cycle, the creep strength was much improved even if the fine PAG was formed. From these results, it is concluded that fine-grained microstructure cannot account for the occurrence of type IV failure, and it only has a small effect during long-term creep. The most important factor is the precipitate formation behavior at various boundaries. Without sufficient boundary strengthening by precipitates, the microstructure of A c3 HAZ undergoes severe changes even during PWHT and causes premature failure during creep.

  8. Advances in the application of in situ electrical resistance heating

    SciTech Connect

    Smith, Gregory J.; Beyke, Gregory

    2007-07-01

    Electrical Resistance Heating (ERH) is an aggressive in situ thermal remediation technology that was developed by the U.S. Department of Energy from the original oil production technology to enhance vapor extraction remediation technologies in low permeability soils. Soil and groundwater are heated by the passage of electrical current through saturated and unsaturated soil between electrodes, not by the electrodes themselves. It is the resistance to the flow of electrical current that results in increased subsurface temperatures, and this is typically applied to the boiling point of water. It is estimated that more than 75 ERH applications have been performed. Capacity to perform these projects has increased over the years, and as many as 15 to 20 of these applications now being performed at any given time, mainly in North America, with some European applications. While the main focus has been to vaporize volatile organic compounds, as one would expect other semi-volatile and non-volatile organic compounds have also been encountered, resulting in observations of chemical and physical reactions that have not been normally incorporated into environmental restoration projects. One such reaction is hydrolysis, which is slow under normal groundwater temperatures, becomes very rapid under temperatures that can easily be achieved using ERH. As a result, these chemical and physical reactions are increasing the applicability of ERH in environmental restoration projects, treating a wider variety of compounds and utilizing biotic and abiotic mechanisms to reduce energy costs. For the treatment of oil and coal tar residues from manufactured gas plants, a process TRS has called steam bubble floatation is used to physically remove the coal and oil tar from the soils for collection using conventional multi-phase collection methods. Heat-enhanced hydrolysis has been used to remediate dichloromethane from soils and groundwater at a site in Illinois, while heat-enhanced biotic and

  9. Explosive Surface Hardening of Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kovacs-Coskun, T.

    2016-04-01

    In this study, the effects of explosion hardening on the microstructure and the hardness of austenitic stainless steel have been studied. The optimum explosion hardening technology of austenitic stainless steel was researched. In case of the explosive hardening used new idea mean indirect hardening setup. Austenitic stainless steels have high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Upon the explosion impact, the deformation mechanism indicates a plastic deformation and this deformation induces a phase transformation (martensite). The explosion hardening enhances the mechanical properties of the material, includes the wear resistance and hardness. In case of indirect hardening as function of the setup parameters specifically the flayer plate position the hardening increased differently. It was find a relationship between the explosion hardening setup and the hardening level.

  10. The 1,2,4-oxadiazole elastomers. [heat resistant polymers

    NASA Technical Reports Server (NTRS)

    Rosser, R. W.; Shalhoub, I. M.; Kwong, H. (Inventor)

    1981-01-01

    Crosslinked 1,2,4-oxadiazole elastomers were prepared either by thermally condensing a monomer having the formula HwN(HON)C-R-Q, wherein Q is a triazine ring forming group such as nitrile or amidine, or by a mixture of said monomer with RC(NOH)NH22, with R in these formulas standing for a bivalent organic radical containing fluorine, hydrogen, or trifluoromethyl. In the monomer charge, the overall proportions of amidoxime groups to triazine ring forming groups varies depending on the extent of crosslinking desired in the final polymer. The heat and chemical resistant elastomers disclosed can serve, for instance, as adhesives, caulking compounds, channel sealants, fuel tank liners.

  11. Heat resistant alloys as interconnect materials of reduced temperature SOFCs

    NASA Astrophysics Data System (ADS)

    Jian, Li; Jian, Pu; Guangyuan, Xie; Shunxu, Wang; Jianzhong, Xiao

    Heat-resistant alloys, Haynes 230 and SS310, were exposed to air and humidified H 2 at 750 °C for up to 1000 h, respectively, simulating the environments in reduced temperature solid oxide fuel cells (SOFCs). The oxidized samples were characterized by using SEM, EDS and X-ray diffraction to obtain the morphology, thickness, composition and crystal structure of the oxide scales. A mechanism for the formation of metallic Ni-rich nodules on top of the oxide scale in Haynes 230 sample oxidized in humidified H 2 was established. Thermodynamic analysis confirmed that MnCr 2O 4 is the favored spinel phase, together with Cr 2O 3, in the oxide scales.

  12. Integrated Thermal Protection Systems and Heat Resistant Structures

    NASA Technical Reports Server (NTRS)

    Pichon, Thierry; Lacoste, Marc; Glass, David E.

    2006-01-01

    In the early stages of NASA's Exploration Initiative, Snecma Propulsion Solide was funded under the Exploration Systems Research & Technology program to develop integrated thermal protection systems and heat resistant structures for reentry vehicles. Due to changes within NASA's Exploration Initiative, this task was cancelled early. This presentation provides an overview of the work that was accomplished prior to cancellation. The Snecma team chose an Apollo-type capsule as the reference vehicle for the work. They began with the design of a ceramic aft heatshield (CAS) utilizing C/SiC panels as the capsule heatshield, a C/SiC deployable decelerator and several ablators. They additionally developed a health monitoring system, high temperature structures testing, and the insulation characterization. Though the task was pre-maturely cancelled, a significant quantity of work was accomplished.

  13. Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by austenitic filler metal

    SciTech Connect

    Eghlimi, Abbas; Shamanian, Morteza; Eskandarian, Masoomeh; Zabolian, Azam; Szpunar, Jerzy A.

    2015-08-15

    The evolution of microstructure and texture across an as-welded dissimilar UNS S32750 super duplex/UNS S30403 austenitic stainless steel joint welded by UNS S30986 (AWS A5.9 ER309LMo) austenitic stainless steel filler metal using gas tungsten arc welding process was evaluated by optical micrography and EBSD techniques. Due to their fabrication through rolling process, both parent metals had texture components resulted from deformation and recrystallization. The weld metal showed the highest amount of residual strain and had large austenite grain colonies of similar orientations with little amounts of skeletal ferrite, both oriented preferentially in the < 001 > direction with cub-on-cube orientation relationship. While the super duplex stainless steel's heat affected zone contained higher ferrite than its parent metal, an excessive grain growth was observed at the austenitic stainless steel's counterpart. At both heat affected zones, austenite underwent some recrystallization and formed twin boundaries which led to an increase in the fraction of high angle boundaries as compared with the respective base metals. These regions showed the least amount of residual strain and highest amount of recrystallized austenite grains. Due to the static recrystallization, the fraction of low degree of fit (Σ) coincident site lattice boundaries, especially Σ3 boundaries, was increased in the austenitic stainless steel heat affected zone, while the formation of subgrains in the ferrite phase increased the content of < 5° low angle boundaries at that of the super duplex stainless steel. - Graphical abstract: Display Omitted - Highlights: • Extensive grain growth in the HAZ of austenitic stainless steel was observed. • Intensification of < 100 > orientated grains was observed adjacent to both fusion lines. • Annealing twins with Σ3 CSL boundaries were formed in the austenite of both HAZ. • Cub-on-cube OR was observed between austenite and ferrite in the weld metal.

  14. Experience of application of a heat-resistant coating to protect billets in heating for metal forming

    NASA Astrophysics Data System (ADS)

    Radyuk, A. G.; Titlyanov, A. E.; Glukhov, L. M.

    2015-12-01

    The purpose of the work is to search for heat-resistant coatings for titanium and steel billets upon heating for metal forming. A water-based heat-resistant coating, which has an operating temperature of 1200°C and a binder consisting of an acrylic emulsion with additions of colloidal graphite, bentonite, and an aluminum powder, is studied. This coating favors a decrease in the thickness of the defective surface layer that forms when titanium and steel billets are heated for metal forming.

  15. A resistive heating system for homeothermic maintenance in small animals

    PubMed Central

    Kersemans, Veerle; Gilchrist, Stuart; Allen, Philip D.; Beech, John S.; Kinchesh, Paul; Vojnovic, Borivoj; Smart, Sean C.

    2015-01-01

    Purpose To develop an MR-compatible resistive heater for temperature maintenance of anaesthetized animals. Materials and Methods An MR-compatible resistive electrical heater was formed from a tightly-wound twisted pair wire, interfaced to a homeothermic maintenance controller. Fat-suppressed images and localized spectra were acquired with the twisted pair heater and a near-identical single strand heater during operation at maximum power. Data were also acquired in the absence of heating to demonstrate the insensitivity of MR to distortions arising from the passage of current through the heater elements. The efficacy of temperature maintenance was examined by measuring rectal temperature immediately following induction of general anesthesia and throughout and after the acquisition of a heater artifact-prone image series. Results Images and spectra acquired in the presence and absence of DC current through the twisted pair heater were identical whereas the passage of current through the single strand wire created field shifts and lineshape distortions. Temperature that is lost during anesthesia induction was recovered within approximately 10–20 minutes of induction, and a stable temperature is reached as the animal's temperature approaches the set target. Conclusion The twisted pair wire heater does not interfere with MR image quality and maintains adequate thermal input to the animal to maintain body temperature. PMID:25863135

  16. Frictional heating, fluid pressure, and the resistance to fault motion

    NASA Astrophysics Data System (ADS)

    Lachenbruch, Arthur H.

    1980-11-01

    Expansion of pore fluid caused by frictional heating might have an important effect on the factional resistance and temperature during an earthquake and a controlling influence on the physics of the earthquake process. When confined water is heated, the pressure increases rapidly (≳10 bars/°C). As Sibson (1973) has pointed out, this could cause a sharp reduction of effective normal stress and dynamic friction on the fault surface. Whether or not this transient stress reduction occurs depends upon the tandem operation of several processes, any of which can break the chain that links frictional heat to frictional stress: the friction must cause an appreciable temperature rise (imposing conditions on the width of the shear zone and rate of conductive transport); the temperature rise must cause an appreciable fluid pressure rise (imposing conditions on the rate of pore dilatation or hydrofracturing, and the rate of Darcian transport); the fluid pressure rise must cause an appreciable reduction of friction (requiring the presence of a continuous fluid phase). Each process depends upon event duration, particle velocity, and the initial value of dynamic friction. With the present uncertainty in the controlling parameters (principally permeability, width of the shear zone, initial stress, and factors controlling transient hydrofracture and pore dilatation) a wide variety of fault behavior is possible. Limits to fault behavior for various ranges of the controlling parameters can be estimated from the governing equations, however, and results can be summarized graphically. If the effective stress law applies and pore dilatation is unimportant, dynamic friction would drop from an initial value of 1 kbar to ˜100 bars when shear strain reached 10 for most earthquakes if the permeability were less than 0.1 μdarcy; the maximum temperature rise would be only ˜150°C irrespective of final strain. If the permeability were ≳100 mdarcies, however, friction would be unaffected

  17. Corrosion resistance of GTAW and EBW welded joints of DIN W. Nr. 1.4462 (UNS S31803): Effect of post-weld-heat-treatment

    SciTech Connect

    Brandi, S.D.; Padilha, A.F.; Wolynec, S.

    1996-12-01

    The duplex stainless steels present better corrosion behavior than the conventional stainless steels. This is due to their chemical composition (Cr, Ni, Mo, N) and a balanced microstructure (50% ferrite). It might be an increase on the volumetric fraction of ferrite, depending on the cooling rate after welding. In the same way the chemical composition can be altered by a loss of the alloying elements during welding, such as N. Both phenomena will decrease the corrosion resistance of the weldment. Autogenous GTAW and EBW were used to join the plates. Several corrosion tests were used to evaluate the behavior of the joints in as-welded (AW) and post-welded-heat-treated (PWHT) conditions. The results were analyzed and correlated to the microstructure of the welded joints. The main conclusion of this work is that corrosion resistance of both joint processes (EBW and GTAW) in as-welded condition is inadequate. PWHT (post-weld-heat-treatment) dissolved the chromium-rich precipitates, restored the equilibrium amount of austenite in the joints and recovered their corrosion resistance.

  18. High-Temperature Performance of Cast CF8C-Plus Austenitic Stainless Steel

    SciTech Connect

    Maziasz, Philip J; Pint, Bruce A

    2011-01-01

    Covers and casings of small to medium size gas turbines can be made from cast austenitic stainless steels, including grades such as CF8C, CF3M, or CF10M. Oak Ridge National Laboratory and Caterpillar have developed a new cast austenitic stainless steel, CF8C-Plus, which is a fully austenitic stainless steel, based on additions of Mn and N to the standard Nb-stabilized CF8C steel grade. The Mn addition improves castability, as well as increases the alloy solubility for N, and both Mn and N synergistically act to boost mechanical properties. CF8C-Plus steel has outstanding creep-resistance at 600-900 C, which compares well with Ni-based superalloys such as alloys X, 625, 617, and 230. CF8C-Plus also has very good fatigue and thermal fatigue resistance. It is used in the as-cast condition, with no additional heat-treatments. While commercial success for CF8C-Plus has been mainly for diesel exhaust components, this steel can also be considered for gas turbine and microturbine casings. The purposes of this paper are to demonstrate some of the mechanical properties, to update the long-term creep-rupture data, and to present new data on the high-temperature oxidation behavior of these materials, particularly in the presence of water vapor.

  19. Polymeric Coatings Containing Antioxidants to Improve UV- and Heat Resistance of Chrome-Free Leather

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For automotive upholstery leather, UV and heat resistance are very important qualities, particularly for non-chrome-tanned (chrome-free) leather. One of our research endeavors has focused on an environmentally friendly finishing process that will improve the UV and heat resistance of automobile uph...

  20. Developmental acclimation to low or high humidity conditions affect starvation and heat resistance of Drosophila melanogaster.

    PubMed

    Parkash, Ravi; Ranga, Poonam; Aggarwal, Dau Dayal

    2014-09-01

    Several Drosophila species originating from tropical humid localities are more resistant to starvation and heat stress than populations from high latitudes but mechanistic bases of such physiological changes are largely unknown. In order to test whether humidity levels affect starvation and heat resistance, we investigated developmental acclimation effects of low to high humidity conditions on the storage and utilization of energy resources, body mass, starvation survival, heat knockdown and heat survival of D. melanogaster. Isofemale lines reared under higher humidity (85% RH) stored significantly higher level of lipids and showed greater starvation survival hours but smaller in body size. In contrast, lines reared at low humidity evidenced reduced levels of body lipids and starvation resistance. Starvation resistance and lipid storage level were higher in females than males. However, the rate of utilization of lipids under starvation stress was lower for lines reared under higher humidity. Adult flies of lines reared at 65% RH and acclimated under high or low humidity condition for 200 hours also showed changes in resistance to starvation and heat but such effects were significantly lower as compared with developmental acclimation. Isofemale lines reared under higher humidity showed greater heat knockdown time and heat-shock survival. These laboratory observations on developmental and adult acclimation effects of low versus high humidity conditions have helped in explaining seasonal changes in resistance to starvation and heat of the wild-caught flies of D. melanogaster. Thus, we may suggest that wet versus drier conditions significantly affect starvation and heat resistance of D. melanogaster. PMID:24845200

  1. Low-thermal-resistance, high-electrical-isolation heat intercept connection

    SciTech Connect

    Niemann, R.C.; Gonczy, J.D.; Nicol, T.H.

    1993-07-01

    A method for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection is presented. Electrical conductors often require the removal of heat produced from their normal operation. The heat can be removed by mechanical connection to a refrigeration source. Such connections require both effective heat removal (low thermal resistance) and effective electrical isolation (high electrical resistance and high dielectric strength). Such connections should be straightforward to fabricate and provide reliable performance that is independent of operating temperature. The connection method described here involves clamping, by thermal interference fit, an electrically insulating cylinder between an outer metallic ring and an inner metallic disk.

  2. Low-thermal-resistance, high-electrical-isolation heat intercept connection

    SciTech Connect

    Niemann, R.C.; Gonczy, J.D. ); Nicol, T.H. )

    1993-01-01

    A method for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection is presented. Electrical conductors often require the removal of heat produced from their normal operation. The heat can be removed by mechanical connection to a refrigeration source. Such connections require both effective heat removal (low thermal resistance) and effective electrical isolation (high electrical resistance and high dielectric strength). Such connections should be straightforward to fabricate and provide reliable performance that is independent of operating temperature. The connection method described here involves clamping, by thermal interference fit, an electrically insulating cylinder between an outer metallic ring and an inner metallic disk.

  3. Carbon content of austenite in austempered ductile iron

    SciTech Connect

    Chang, L.C.

    1998-06-05

    The development of austempered ductile iron (ADI) is a major achievement in cast iron technology. The austempering heat treatment enables the ductile cast iron containing mainly strong bainitic ferrite and ductile carbon-enriched austenite, with some martensite transforms from austenite during cooling down to room temperature. A key factor controlling the stability of the retained austenite can be evaluated soundly using the thermodynamics principles. It is the purpose here to demonstrate that the data of ADI from numerous sources have a similar trend.

  4. Heat-Resistant Crack-Free Superhydrophobic Polydivinylbenzene Colloidal Films.

    PubMed

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-03-29

    Highly cross-linked poly(divinylbenzene) (PDVB) spherical colloidal particles with nano-, submicron-, and micron-sizes of 157.2 nm, 602.1 nm, and 5.1 μm were synthesized through emulsion and dispersion polymerization methods. The influences of particle size on the surface morphology, roughness, superhydrophobicity, and critical cracking thickness of colloidal films were studied in detail. The results show that PDVB colloidal films possess large water contact angle (CA) over 151°, belonging to superhydrophobic materials. Moreover, it is interesting to observe that the highly cross-linked network structure leads to PDVB film's excellent heat-resistance. The CA and rough surface morphology remain nearly unchanged after thermal-treatment of films at 150 °C for 24 h. In addition, no cracks were observed in films with thicknesses up to 8.1 μm, exceeding most of polymer and inorganic particle films reported in the literature. The simple and scalable preparation method, low-cost, superhydrophobicity, and excellent thermal stability endow the PDVB colloidal films with promising applications in advanced coating fields, especially when employed in the high-temperature service environment. PMID:26986041

  5. Monitoring radio-frequency heating of contaminated soils using electrical resistance tomography

    SciTech Connect

    Ramirez, A.L.; Daily, W.D.

    1993-09-01

    Electrical resistance tomography (ERT) was used to monitor a radio-frequency heating process for the insitu remediation of volatile organic compounds from subsurface water and soil at the Savannah River Site, near Aiken, South Carolina. A dipole antenna located in a horizontal well in the unsaturated zone was used to heat a contaminated clay layer. The heat-induced changes were tomographically imaged by their effects on the formation electrical resistivity. The resistivity changes observed appear to be related to heating and vaporization of the pore water, formation of steam condensate, and infiltration of rainwater through the heated zones and adjacent areas. There is a clear asymmetry downward in the resistivity decreases associated with the heating process. The resistivity decreases observed in the vicinity of the heating well are believed to be caused by the heating and downward migration of warm water originally located within a radius of a few feet around the heating well; the magnitude of the change is between 10--20%. The decreasing resistivity implies an increasing rate of radio wave attenuation as heating progressed; therefore, the rate of energy deposition around the heating well increased while the penetration distance of the radio waves decreased. Saturation changes in the clay near the antenna during heating were estimated to be 50--55% based on the observed resistivity decreases. Resistivity changes observed at distances greater than 3 meters to one side of the antenna appear to be related to rainwater infiltration. We propose that gaps in near surface clay layers allow rainwater to migrate downward and reach the top of clay rich zone penetrated by the antenna borehole. The water may then accumulate along the top of the clay.

  6. Heat Resistance of Salmonella: the Uniqueness of Salmonella senftenberg 775W

    PubMed Central

    Ng, Henry; Bayne, Henry G.; Garibaldi, John A.

    1969-01-01

    Of approximately 300 cultures of Salmonella, representing 75 different serotypes, none was found to be as heat-resistant as S. senftenberg 775W. However, S. blockley 2004 was 5 times more heat-resistant and S. senftenberg 775W was 30 times more heat-resistant than S. typhimurium Tm-1, the reference strain in this study. All other strains of Salmonella tested, including 19 strains of S. senftenberg and 7 strains of S. blockley, had decimal reduction times at 57 C of about 1 min, equivalent to that of the reference organism, Tm-1. As observed in other bacterial species, strain 775W is more heat-sensitive in the log phase than in the stationary phase of growth. Cells from cultures grown at 44 C were more heat-resistant than those grown at either 35 or 15 C; the medium of growth, whether minimal or complex, made no appreciable difference in heat resistance. Cells from cultures limited by a carbon source were killed at a much slower rate than those limited by a nitrogen source and exhibited a 1-hr lag at 55 C before a significant rate of kill was attained. For any given set of growth conditions, strain 775W was always more heat-resistant than another strain of S. senftenberg, 197B, which has normal heat resistance. PMID:5774764

  7. The resistance to heat of thermo-resistant streptococci attached to stainless steel in the presence of milk.

    PubMed

    Flint, S; Brooks, J; Bremer, P; Walker, K; Hausman, E

    2002-03-01

    Skim milk residues had a significant impact on the sensitivity to heat of a dairy isolate of the thermo-resistant, Streptococcus thermophilus. Cells of S. thermophilus (H) suspended in water or in milk had D values at 60 degrees C of 2.0 and 14 min, respectively. Cells of S. thermophilus (H) attached to stainless steel in the presence of water or milk had D values at 60 degrees C of 2.2 and 8.1 min, respectively. The attached cells in both experiments were heat-treated in the presence of water. The increase in heat resistance could not be fully attributed to individual components (caseinate or whey) in the milk. The potential for thermo-resistant streptococci to survive heat treatment in a dairy manufacturing plant is therefore greater than may be expected for the organism in less complex environments. PMID:12074086

  8. Modeling of Austenite Grain Growth During Austenitization in a Low Alloy Steel

    NASA Astrophysics Data System (ADS)

    Dong, Dingqian; Chen, Fei; Cui, Zhenshan

    2016-01-01

    The main purpose of this work is to develop a pragmatic model to predict austenite grain growth in a nuclear reactor pressure vessel steel. Austenite grain growth kinetics has been investigated under different heating conditions, involving heating temperature, holding time, as well as heating rate. Based on the experimental results, the mathematical model was established by regression analysis. The model predictions present a good agreement with the experimental data. Meanwhile, grain boundary precipitates and pinning effects on grain growth were studied by transmission electron microscopy. It is found that with the increasing of the temperature, the second-phase particles tend to be dissolved and the pinning effects become smaller, which results in a rapid growth of certain large grains with favorable orientation. The results from this study provide the basis for the establishment of large-sized ingot heating specification for SA508-III steel.

  9. Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Bojack, A.; Zhao, L.; Morris, P. F.; Sietsma, J.

    2016-05-01

    The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stages. This is probably due to inhomogeneous distribution of the austenite-stabilizing elements Ni and Mn, resulting from their slow diffusion from martensite into austenite and carbide and nitride dissolution during the second, higher temperature, stage. A better homogenization of the material causes an increase in the transformation temperatures for the martensite-to-austenite transformation and a lower retained austenite fraction with less variability after tempering. Furthermore, the martensite-to-austenite transformation was found to be incomplete at the target temperature of 1223 K (950 °C), which is influenced by the previous austenitization treatment and the heating rate. The activation energy for martensite-to-austenite transformation was determined by a modified Kissinger equation to be approximately 400 and 500 kJ/mol for the first and the second stages of transformation, respectively. Both values are much higher than the activation energy found during isothermal treatment in a previous study and are believed to be effective activation energies comprising the activation energies of both mechanisms involved, i.e., nucleation and growth.

  10. Sensitization of 21% Cr Ferritic Stainless Steel Weld Joints Fabricated With/Without Austenitic Steel Foil as Interlayer

    NASA Astrophysics Data System (ADS)

    Wu, Wenyong; Hu, Shengsun; Shen, Junqi; Ma, Li; Han, Jian

    2015-04-01

    The effects of sensitization heat treatment on the microstructure and electrochemical behavior of 21% Cr ferritic stainless steel weld joints with or without 309L austenite stainless steel as an interlayer were investigated. The joints were processed by pulsed gas tungsten arc welding. With the interlayer, grains in weld bead were refined, and almost fully ferrite. When the joints with the interlayer were maintained at 500 °C for 1 and 4 h, no microstructure changes occurred, whereas Widmanstatten austenite and needle-like austenite formed in the weld bead after sensitization at 815 °C for 1 h. In general, sensitization treatment worsens the corrosion resistance of welds, but the resistance of samples with the 4-h treatment at 500 °C recovered in part compared to those subjected to sensitization at 500 °C for 1 h. This could be due to Cr diffusion from the ferrite that heals the chromium-depletion zone along the grain boundary. However, an increase in temperature does not have the same effect. The corrosion morphology of samples in the weld bead is different from those in base metal after heat treatment at 500 °C for 1 h; in base metal, pitting corrosion occurs, whereas grain boundary corrosion occurs in the weld bead. Corrosion morphology is closely associated with precipitation and segregation along the grain boundary.

  11. Hydrogen-resistant heat pipes for bimodal reactors

    NASA Astrophysics Data System (ADS)

    North, Mark T.; Anderson, William G.

    1997-01-01

    A sodium heat pipe that is tolerant of hydrogen permeation was developed for bimodal space power applications. Hydrogen permeation out of the heat pipe is enhanced by using a condenser design with a re-entrant annular gas cavity and an array of small diameter, thin-walled tubes to increase the permeation area. An experimental heat pipe with a nickel envelope was fabricated and tested. The heat pipe operated between 993K and 1073K, using sodium as the working fluid. During steady-state operation, hydrogen gas was injected into the heat pipe. The response of the heat pipe was monitored while the hydrogen permeated out of the heat pipe in the condenser section. For each of the tests run, the hydrogen gas was removed from the heat pipe in approximately 5 to 10 minutes. A model of the experimental heat pipe was developed to predict the enhancement in the hydrogen permeation rate out of the heat pipe. A significant improvement in the rate at which hydrogen permeates out of a heat pipe was predicted for the use of the special condenser geometry developed here. Agreement between the model and the experimental results was qualitatively good. Inclusion of the additional effects of fluid flow in the heat pipe are recommended for future work.

  12. Heat-resistant fungi of importance to the food and beverage industry.

    PubMed

    Tournas, V

    1994-01-01

    Spoilage of pasteurized and canned fruit and fruit products caused by heat-resistant molds have been reported repeatedly in recent years. Species most commonly implicated in fruit and fruit product disintegration are Byssochlamys fulva, Byssochlamys nivea, Neosartorya fischeri, Talaromyces flavus, and Eupenicillium brefeldianum. These organisms are saprophytic rather than parasitic and usually contaminate fruits on or near the ground. They can survive heat treatments used for fruit processing and can grow and spoil the products during storage at room temperature, which results in great economic losses. Mold heat resistance is attributed to the formation of sexual spores, ascospores. Ascospores have a wide range of heat resistance, depending on species, strain, age of organism, heating medium, pH, presence of sugars, fats, and acids in heating medium, growth conditions, etc. The mechanism(s) of thermoresistance are not clear; probably some very stable compound(s) critical to germination and outgrowth are present in the heat-resistant ascospores. Besides spoilage, the heat-resistant molds produce a number of toxic secondary metabolites, such as byssotoxin A; byssochlamic acid; the carcinogen, patulin, the tremorgenic substances, fumitremorgin A and C, and verruculogen; fischerin, which caused fatal peritonitis in mice; and eupenifeldin, a compound possessing cytotoxicity as well as in vivo antitumor activity. Growth of heat-resistant fungi can be controlled by lowering the water activity, adding sulfur dioxide, sorbate, or benzoate; washing of fruits in hypochlorite solution before heat treatment reduces the number of ascospores and makes the heat destruction more successful. More research is needed to elucidate the mechanism(s) of thermoresistance and develop new methods for the complete inactivation of resistant ascospores. PMID:7857517

  13. Heat-shock induction of ultraviolet light resistance in Saccharomyces cerevisiae

    SciTech Connect

    Mitchel, R.E.J.; Morrison, D.P.

    1983-10-01

    When exponentially growing diploid wild type Saccharomyces cervisiae cells were subjected to a sudden rise in temperature (heat shock) they responded by increasing their resistance to the lethal effects of ultraviolet light. We have previously reported heat shock-induced increases in heat and ionizing radiation resistance. The shock-induced rise in resistance to uv light reported here was examined in terms of DNA repair capacity, and we find that the increase is due to induction of the recombinational repair system with no significant response from the uv-excision repair process.

  14. Effect of thymol in heating and recovery media on the isothermal and non-isothermal heat resistance of Bacillus spores.

    PubMed

    Esteban, Maria-Dolores; Conesa, Raquel; Huertas, Juan-Pablo; Palop, Alfredo

    2015-06-01

    Members of the genus Bacillus include important food-borne pathogen and spoilage microorganisms for food industry. Essential oils are natural products extracted from herbs and spices, which can be used as natural preservatives in many foods because of their antibacterial, antifungal, antioxidant and anti-carcinogenic properties. The aim of this research was to explore the effect of the addition of different concentrations of thymol to the heating and recovery media on the thermal resistance of spores of Bacillus cereus, Bacillus licheniformis and Bacillus subtilis at different temperatures. While the heat resistance was hardly reduced when thymol was present in the heating medium, the effect in the recovery medium was greater, reducing the D100 °C values down to one third for B. subtilis and B. cereus when 0.5 mM thymol was added. This effect was dose dependent and was also observed at other heating temperatures. PMID:25790989

  15. Quantifying variety-specific heat resistance and the potential for adaptation to climate change.

    PubMed

    Tack, Jesse; Barkley, Andrew; Rife, Trevor W; Poland, Jesse A; Nalley, Lawton Lanier

    2016-08-01

    The impact of climate change on crop yields has become widely measured; however, the linkages for winter wheat are less studied due to dramatic weather changes during the long growing season that are difficult to model. Recent research suggests significant reductions under warming. A potential adaptation strategy involves the development of heat resistant varieties by breeders, combined with alternative variety selection by producers. However, the impact of heat on specific wheat varieties remains relatively unstudied due to limited data and the complex genetic basis of heat tolerance. Here, we provide a novel econometric approach that combines field-trial data with a genetic cluster mapping to group wheat varieties and estimate a separate extreme heat impact (temperatures over 34 °C) across 24 clusters spanning 197 varieties. We find a wide range of heterogeneous heat resistance and a trade-off between average yield and resistance. Results suggest that recently released varieties are less heat resistant than older varieties, a pattern that also holds for on-farm varieties. Currently released - but not yet adopted - varieties do not offer improved resistance relative to varieties currently grown on farm. Our findings suggest that warming impacts could be significantly reduced through advances in wheat breeding and/or adoption decisions by producers. However, current adaptation-through-adoption potential is limited under a 1 °C warming scenario as increased heat resistance cannot be achieved without a reduction in average yields. PMID:26577840

  16. Heat resistance of Salmonella enterica is increased by pre-adaptation to peanut oil or sub-lethal heat exposure.

    PubMed

    Fong, Karen; Wang, Siyun

    2016-09-01

    Cross-protection represents a considerable challenge in the food industry where hurdled interventions are often employed to reduce Salmonella contamination. The heat resistance of Salmonella strains from five serotypes (i.e., Typhimurium, Enteritidis, Tennessee, Thompson and Hartford) at 70 °C was determined by measurement of viable cell populations before and after adaptation to two common stresses employed in low-water activity food processing, desiccation and sub-lethal heat treatment. Survival of Salmonella at 70 °C significantly increased (p < 0.05) following the six-day incubation in peanut oil (aw 0.52 ± 0.00) and/or the exposure to a sub-lethal heat treatment at 45 °C for 3 min. Quantitative PCR revealed upregulation of two desiccation stress-related genes, fadA and otsB, following the peanut oil incubation, whereas heat treatment induced upregulation of a heat-resistance gene, dnaK. Invasion gene invA and alternative sigma factor rpoE were downregulated following either of the treatments. Interestingly, different Salmonella strains yielded different transcriptional profiles. The strain-specific resistance phenotypes and transcriptional profiles provided further insights into the mechanisms employed to tolerate desiccation and heat stresses in the food industry. PMID:27217370

  17. Heat exchange and hydraulic resistance of compact laser mirror cooling systems

    NASA Astrophysics Data System (ADS)

    Shanin, Yu. I.; Shanin, O. I.

    2013-07-01

    The hydraulic resistance of cooling systems for laser mirrors and the heat exchange in them have been investigated experimentally. The data obtained have been generalized for several cooling systems with different porous elements.

  18. Heating power lowering by downscaling the cell dimensions in nanoscale filamentary resistive switching devices

    NASA Astrophysics Data System (ADS)

    Yin, Qiaonan; Chen, Yan; Xia, Yidong; Xu, Bo; Yin, Jiang; Liu, Zhiguo

    2016-04-01

    In this work, we theoretically investigate the size dependence of the heat process in thermochemical filamentary resistive switching memories of crossbar structure. The equivalent heat resistance of the system increases with the device dimensions scaled down because of the size-dependent electric and thermal conductivity and geometry configurations. The higher equivalent heat resistance by diminishing the cell sizes induces an enhanced self-heating effect of the filament. It promises lower operation voltage and heating power to trigger the thermally activated dissolution of the filament in RESET process. These results strengthen the advantage of filamentary memories in lateral and longitudinal scaling down technologies where less power consumption has long been urged. Our results also show the opposite dependence of the driven electric field on the linewidth and thickness of the device.

  19. Effect of ultrasonic waves on the heat resistance of Bacillus cereus and Bacillus licheniformis spores.

    PubMed

    Burgos, J; Ordóñez, J A; Sala, F

    1972-09-01

    Heat resistance of Bacillus cereus and Bacillus licheniformis spores in quarter-strength Ringer solution decreases markedly after ultrasonic treatments which are unable to kill a significant proportion of the spore population. This effect does not seem to be caused by a loss of Ca(2+) or dipicolinic acid. The use of ultrasonics to eliminate vegetative cells or to break aggregates in Bacillus spore suspensions to be used subsequently in heat resistance experiments appears to be unadvisable. PMID:4627969

  20. A study of the dry heat resistance of naturally occurring organisms widely dispersed on a surface

    NASA Technical Reports Server (NTRS)

    Garst, D. M.; Lindell, K. F.

    1971-01-01

    Although Bacillus subtilis var. niger is the standard test organism for NASA planetary quarantine sterilization studies, it was found that some naturally occurring soil organisms are more heat resistant. The separation of these organisms from soil particles is described. Experiments are discussed which were designed to show that the heat resistance is a natural characteristic of the organisms, rather than a condition induced by the clumping effect of agglomerated particles and organisms.

  1. Influence of cyclopropane fatty acids on heat, high pressure, acid and oxidative resistance in Escherichia coli.

    PubMed

    Chen, Yuan Yao; Gänzle, Michael G

    2016-04-01

    Heat and high pressure resistant strains of Escherichia coli are a challenge to food safety. This study investigated effects of cyclopropane fatty acids (CFAs) on stress tolerance in the heat- and pressure-resistant strain E. coli AW1.7 and the sensitive strain E. coli MG1655. The role of CFAs was explored by disruption of cfa coding for CFA synthase with an in-frame, unmarked deletion method. Both wild-type strains consumed all the unsaturated fatty acids (C16:1 and C18:1) that were mostly converted to CFAs and a low proportion to saturated fatty acid (C16:0). Moreover, E. coli AW1.7 contained a higher proportion of membrane C19:0 cyclopropane fatty acid than E. coli MG1655 (P<0.05). The Δcfa mutant strains did not produce CFAs, and the corresponding substrates C16:1 and C18:1 accumulated in membrane lipids. The deletion of cfa did not alter resistance to H2O2 but increased the lethality of heat, high pressure and acid treatments in E. coli AW1.7, and E. coli MG1655. E. coli AW1.7 and its Δcfa mutant were more resistant to pressure and heat but less resistant to acid stress than E. coli MG1655. Heat resistance of wild-type strains and their Δcfa mutant was also assessed in beef patties grilled to an internal temperature of 71 °C. After treatment, cell counts of wild type strains were higher than those of the Δcfa mutant strains. In conclusion, CFA synthesis in E. coli increases heat, high pressure and acid resistance, and increases heat resistance in food. This knowledge on mechanisms of stress resistance will facilitate the design of intervention methods for improved pathogen control in food production. PMID:26828814

  2. Method for restoring the resistance of indium oxide semiconductors after heating while in sealed structures

    DOEpatents

    Seager, Carleton H.; Evans, Jr., Joseph Tate

    1998-01-01

    A method for counteracting increases in resistivity encountered when Indium Oxide resistive layers are subjected to high temperature annealing steps during semiconductor device fabrication. The method utilizes a recovery annealing step which returns the Indium Oxide layer to its original resistivity after a high temperature annealing step has caused the resistivity to increase. The recovery anneal comprises heating the resistive layer to a temperature between 100.degree. C. and 300.degree. C. for a period of time that depends on the annealing temperature. The recovery is observed even when the Indium Oxide layer is sealed under a dielectric layer.

  3. Method for restoring the resistance of indium oxide semiconductors after heating while in sealed structures

    DOEpatents

    Seager, C.H.; Evans, J.T. Jr.

    1998-11-24

    A method is described for counteracting increases in resistivity encountered when Indium Oxide resistive layers are subjected to high temperature annealing steps during semiconductor device fabrication. The method utilizes a recovery annealing step which returns the Indium Oxide layer to its original resistivity after a high temperature annealing step has caused the resistivity to increase. The recovery anneal comprises heating the resistive layer to a temperature between 100 C and 300 C for a period of time that depends on the annealing temperature. The recovery is observed even when the Indium Oxide layer is sealed under a dielectric layer. 1 fig.

  4. Precipitation hardening austenitic superalloys

    DOEpatents

    Korenko, Michael K.

    1985-01-01

    Precipitation hardening, austenitic type superalloys are described. These alloys contain 0.5 to 1.5 weight percent silicon in combination with about 0.05 to 0.5 weight percent of a post irradiation ductility enhancing agent selected from the group of hafnium, yttrium, lanthanum and scandium, alone or in combination with each other. In addition, when hafnium or yttrium are selected, reductions in irradiation induced swelling have been noted.

  5. Porphyrin photosensitivity in cell lines expressing a heat-resistant phenotype

    NASA Astrophysics Data System (ADS)

    Gomer, Charles J.; Rucker, Natalie; Wong, Sam

    1990-07-01

    In-vitro sensitivity to porphyrin mediated photodynamic therapy (PDT) has been examined in cell lines resistant to hyperthermia. Parental (HA-i) and heat resistant (3012) Chinese hamster fibroblasts as well as parental (RIF-i) and temperature resistant (TR-4, TR-5 and TR-iO) mouse radiation-induced fibrosarcoma cells were evaluated for thermal and PDT sensitivity. Quantitative survival curves were generated and porphyrin uptake properties were obtained for all cell lines. Significant resistance to hyperthermia (450C for varying exposure periods) was documented for the 3012 and TR cell strains when compared to 'the parent lines. However, normal and heat resistant clones exhibited comparable levels of porphyrin uptake and photosensitivity. Our results indicate that cross resistance between hyperthermia and PDT is not observed and that members of the 70 kD heat shock protein family (which are elevated in the thermal resistant cells and may be associated with the heat resistant phenotype) do not play a significant role in modulating PDT sensitivity. Mechanisms of in-vitro cytotoxicity appear to be different for PDT and hyperthermia even though possible subcellular targets (such as the plasma membrane) and types of damage (protein denaturation) may be similar for the two modalities.

  6. Investigation of heat-resistant layered coating of Al-Cr-Ni

    NASA Astrophysics Data System (ADS)

    Shmorgun, V. G.; Trykov, Y. P.; Bogdanov, A. I.; Taube, A. O.

    2016-02-01

    The paper shows the transformation of the structure and phase composition of the layered coating system Al-Cr-Ni, obtained by the heat treatment of multilayered composite H20N80+AD1, welded by explosion, in the time range 1-300 hours. The cyclic heat resistance of the coating at 1150 ° C is studied.

  7. Modelling the influence of the sporulation temperature upon the bacterial spore heat resistance, application to heating process calculation.

    PubMed

    Leguérinel, I; Couvert, O; Mafart, P

    2007-02-28

    Environmental conditions of sporulation influence bacterial heat resistance. For different Bacillus species a linear Bigelow type relationship between the logarithm of D values determined at constant heating temperature and the temperature of sporulation was observed. The absence of interaction between sporulation and heating temperatures allows the combination of this new relationship with the classical Bigelow model. The parameters zT and zT(spo) of this global model were fitted to different sets of data regarding different Bacillus species: B. cereus, B. subtilis, B. licheniformis, B. coagulans and B. stearothermophilus. The origin of raw products or food process conditions before a heat treatment can lead to warm temperature conditions of sporulation and to a dramatic increase of the heat resistance of the generated spores. In this case, provided that the temperature of sporulation can be assessed, this model can be easily implemented to rectify F values on account of possible increase of thermal resistance of spores and to ensure the sterilisation efficacy. PMID:17184868

  8. The effect of heat treatment on the resistivity of polycrystalline silicon films

    NASA Technical Reports Server (NTRS)

    Fripp, A. L., Jr.

    1975-01-01

    The resistivity of doped polycrystalline silicon films has been studied as a function of post deposition heat treatments in an oxidizing atmosphere. It was found that a short oxidation cycle may produce a resistivity increase as large as three orders of magnitude in the polycrystalline films. The extent of change was dependent on the initial resistivity and the films' doping level and was independent of the total oxidation time.

  9. Aluminum nitride bulk crystal growth in a resistively heated reactor

    NASA Astrophysics Data System (ADS)

    Dalmau, Rafael Federico

    A resistively heated reactor capable of temperatures in excess of 2300°C was used to grow aluminum nitride (AlN) bulk single crystals from an AlN powder source by physical vapor transport (PVT) in nitrogen atmosphere. AlN crystals were grown at elevated temperatures by two different methods. Self-seeded crystals were obtained by spontaneous nucleation on the crucible walls, while seeded growth was performed on singular and vicinal (0001) surfaces of silicon carbide (SiC) seeds. During self-seeded growth experiments a variety of crucible materials, such as boron nitride, tungsten, tantalum, rhenium, tantalum nitride, and tantalum carbide, were evaluated. These studies showed that the morphology of crystals grown by spontaneous nucleation strongly depends on the growth temperature and contamination in the reactor. Crucible selection had a profound effect on contamination in the crystal growth environment, influencing nucleation, coalescence, and crystal morphology. In terms of high-temperature stability and compatibility with the growth process, the best results for AlN crystal growth were obtained in crucibles made of sintered tantalum carbide or tantalum nitride. In addition, contamination from the commercially purchased AlN powder source was reduced by presintering the powder prior to growth, which resulted in a drastic reduction of nearly all impurities. Spontaneously grown single crystals up to 15 mm in size were characterized by x-ray diffraction, x-ray topography, glow discharge mass spectrometry, and secondary ion mass spectrometry. Average dislocation densities were on the order of 103 cm -3, with extended areas virtually free of dislocations. High resolution rocking curves routinely showed peak widths as narrow as 7 arcsec, indicating a high degree of crystalline perfection. Low-temperature partially polarized optical reflectance measurements were used to calculate the crystal-field splitting parameter of AlN, Deltacr = -230 meV, and a low-temperature (1

  10. Thin-Film Resistance Heat-Flux Sensors

    NASA Technical Reports Server (NTRS)

    Fralick, Gustave C.; Wrbanek, John D.; Blaha, Charles A.

    2005-01-01

    Thin-film heat-flux sensors of a proposed type would offer advantages over currently available thin-film heat flux sensors. Like a currently available thin-film heat-flux sensor, a sensor according to the proposal would be based on measurement of voltages related to the temperatures of thin metal films on the hotter and colder faces of a layer of an electrically insulating and moderately thermally conductive material. The heat flux through such a device is proportional to the difference between the temperatures and to the thermal conductivity of the layer. The advantages of the proposed sensors over the commercial ones would arise from the manner in which the temperature-related voltages would be generated and measured.

  11. Heat Transfer and Hydraulic Flow Resistance for Streams of High Velocity

    NASA Technical Reports Server (NTRS)

    Lelchuk, V. L.

    1943-01-01

    Problems of hydraulic flow resistance and heat transfer for streams with velocities comparable with acoustic have present great importance for various fields of technical science. Especially, they have great importance for the field of heat transfer in designing and constructing boilers.of the "Velox" type. In this article a description of experiments and their results as regards definition of the laws of heat transfer in differential form for high velocity air streams inside smooth tubes are given.

  12. Direct Resistance Joule Heating of Al-10 pct Si-Coated Press Hardening Steel

    NASA Astrophysics Data System (ADS)

    Lee, Chang Wook; Choi, Won Seok; Cho, Yeol Rae; De Cooman, Bruno C.

    2016-06-01

    Various rapid heating methods have been developed to increase the productivity of press hardening steel. One of these methods is direct resistance Joule heating. This heating method results in the melting of the surface coating and the formation of a persistent liquid trail as a result of the high thermal conductivity and low melting temperature of the Al-10 pct Si alloy coating. This can be addressed by an alloying preheating treatment prior to the press hardening process.

  13. Direct Resistance Joule Heating of Al-10 pct Si-Coated Press Hardening Steel

    NASA Astrophysics Data System (ADS)

    Lee, Chang Wook; Choi, Won Seok; Cho, Yeol Rae; De Cooman, Bruno C.

    2016-03-01

    Various rapid heating methods have been developed to increase the productivity of press hardening steel. One of these methods is direct resistance Joule heating. This heating method results in the melting of the surface coating and the formation of a persistent liquid trail as a result of the high thermal conductivity and low melting temperature of the Al-10 pct Si alloy coating. This can be addressed by an alloying preheating treatment prior to the press hardening process.

  14. Design and performance of low-thermal-resistance, high-electrical-isolation heat intercept connections

    NASA Astrophysics Data System (ADS)

    Niemann, R. C.; Gonczy, J. D.; Phelan, P. E.; Nicol, T. H.

    Electrical conductors often require the removal of heat produced by normal operation. The heat can be removed by mechanical connection of the conductor to a refrigeration source. Such connections require both effective heat removal (low thermal resistance) and effective electrical isolation (high electrical resistance and high dielectric strength). Fabrication of these connections should be straightforward, and performance must be reliable and independent of operating temperature. The connection method described here involves clamping (by thermal interference fit) an electrically insulating cylinder between an outer metallic ring and an inner metallic disc. Material candidates for insulating cylinders include composites, e.g. epoxy/fibreglass, and ceramics, e.g. alumina. Design factors, including geometry, materials and thermal contact resistance are discussed. The design, construction experience and performance measurements of a heat intercept connection in a high-temperature superconducting lead assembly is presented.

  15. Heat-resistant protein expression during germination of maize seeds under water stress.

    PubMed

    Abreu, V M; Silva Neta, I C; Von Pinho, E V R; Naves, G M F; Guimarães, R M; Santos, H O; Von Pinho, R G

    2016-01-01

    Low water availability is one of the factors that limit agricultural crop development, and hence the development of genotypes with increased water stress tolerance is a challenge in plant breeding programs. Heat-resistant proteins have been widely studied, and are reported to participate in various developmental processes and to accumulate in response to stress. This study aimed to evaluate heat-resistant protein expression under water stress conditions during the germination of maize seed inbreed lines differing in their water stress tolerance. Maize seed lines 91 and 64 were soaked in 0, -0.3, -0.6, and -0.9 MPa water potential for 0, 6, 12, 18, and 24 h. Line 91 is considered more water stress-tolerant than line 64. The analysis of heat-resistant protein expression was made by gel electrophoresis and spectrophotometry. In general, higher expression of heat-resistant proteins was observed in seeds from line 64 subjected to shorter soaking periods and lower water potentials. However, in the water stress-tolerant line 91, a higher expression was observed in seeds that were subjected to -0.3 and -0.6 MPa water potentials. In the absence of water stress, heat-resistant protein expression was reduced with increasing soaking period. Thus, there was a difference in heat-resistant protein expression among the seed lines differing in water stress tolerance. Increased heat-resistant protein expression was observed in seeds from line 91 when subjected to water stress conditions for longer soaking periods. PMID:27525950

  16. Thermal treatment of low permeability soils using electrical resistance heating

    SciTech Connect

    Udell, K.S.

    1996-08-01

    The acceleration of recovery rates of second phase liquid contaminants from the subsurface during gas or water pumping operations is realized by increasing the soil and ground water temperature. Electrical heating with AC current is one method of increasing the soil and groundwater temperature and has particular applicability to low permeability soils. Several mechanisms have been identified that account for the enhanced removal of the contaminants during electrical heating. These are vaporization of liquid contaminants with low boiling points, temperature-enhanced evaporation rates of semi-volatile components, and removal of residual contaminants by the boiling of residual water. Field scale studies of electrical heating and fluid extraction show the effectiveness of this technique and its applicability to contaminants found both above and below the water table and within low permeability soils. 10 refs., 8 figs.

  17. Heat resistant substrates and battery separators made therefrom

    NASA Technical Reports Server (NTRS)

    Langer, Alois (Inventor); Scala, Luciano C. (Inventor); Ruffing, Charles R. (Inventor)

    1976-01-01

    A flexible substrate having a caustic resistant support and at least one membrane comprising a solid polymeric matrix containing a network of interconnected pores and interdispersed inorganic filler particles with a ratio of filler: polymer in the polymeric matrix of between about 1:1 to 5:1, is made by coating at least one side of the support with a filler:coating formulation mixture of inorganic filler particles and a caustic resistant, water insoluble polymer dissolved in an organic solvent, and removing the solvent from the mixture to provide a porous network within the polymeric matrix.

  18. In Situ Thermo-magnetic Investigation of the Austenitic Phase During Tempering of a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Bojack, A.; Zhao, L.; Morris, P. F.; Sietsma, J.

    2014-09-01

    The formation of austenite during tempering of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) was investigated using an in situ thermo-magnetic technique to establish the kinetics of the martensite to austenite transformation and the stability of austenite. The austenite fraction was obtained from in situ magnetization measurements. It was found that during heating to the tempering temperature 1 to 2 vol pct of austenite, retained during quenching after the austenitization treatment, decomposed between 623 K and 753 K (350 °C and 480 °C). The activation energy for martensite to austenite transformation was found by JMAK-fitting to be 233 kJ/mol. This value is similar to the activation energy for Ni and Mn diffusion in iron and supports the assumption that partitioning of Ni and Mn to austenite are mainly rate determining for the austenite formation during tempering. This also indicates that the stability of austenite during cooling after tempering depends on these elements. With increasing tempering temperature the thermal stability of austenite is decreasing due to the lower concentrations of austenite-stabilizing elements in the increased fraction of austenite. After cooling from the tempering temperature the retained austenite was further partially decomposed during holding at room temperature. This appears to be related to previous martensite formation during cooling.

  19. In Situ Thermo-magnetic Investigation of the Austenitic Phase During Tempering of a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Bojack, A.; Zhao, L.; Morris, P. F.; Sietsma, J.

    2014-12-01

    The formation of austenite during tempering of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) was investigated using an in situ thermo-magnetic technique to establish the kinetics of the martensite to austenite transformation and the stability of austenite. The austenite fraction was obtained from in situ magnetization measurements. It was found that during heating to the tempering temperature 1 to 2 vol pct of austenite, retained during quenching after the austenitization treatment, decomposed between 623 K and 753 K (350 °C and 480 °C). The activation energy for martensite to austenite transformation was found by JMAK-fitting to be 233 kJ/mol. This value is similar to the activation energy for Ni and Mn diffusion in iron and supports the assumption that partitioning of Ni and Mn to austenite are mainly rate determining for the austenite formation during tempering. This also indicates that the stability of austenite during cooling after tempering depends on these elements. With increasing tempering temperature the thermal stability of austenite is decreasing due to the lower concentrations of austenite-stabilizing elements in the increased fraction of austenite. After cooling from the tempering temperature the retained austenite was further partially decomposed during holding at room temperature. This appears to be related to previous martensite formation during cooling.

  20. 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.

  1. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    SciTech Connect

    Pawel, Steven J; Hsu, Julia

    2010-11-01

    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  2. 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

  3. Frictional and heat resistance characteristics of coconut husk particle filled automotive brake pad

    NASA Astrophysics Data System (ADS)

    Bahari, Shahril Anuar; Chik, Mohd Syahrizul; Kassim, Masitah Abu; Som Said, Che Mohamad; Misnon, Mohd Iqbal; Mohamed, Zulkifli; Othman, Eliasidi Abu

    2012-06-01

    The objective of this study was to determine the friction and heat resistance characteristics of automotive brake pad composed with different sizes and percentages of coconut husk particle. The materials used were phenolic resin (phenol formaldehyde) as binder, copper, graphite and brass as friction producer/modifiers, magnesium oxide as abrasive material, steel and barium sulfate as reinforcement while coconut husk particle as filler. To obtain particle, the coconut husk was ground and dried to 3% moisture content. Then the coconut husk particle was screened using 80 mesh (to obtain coarse dust) and 100 mesh (to obtain fine dust). Different percentages of particle, such as 10 and 30% were used in the mixture of brake pad materials. Then the mixture was hot-pressed to produce brake pad. Chase machine was used to determine the friction coefficient in friction resistance testing, while thermogravimetric analyzer (TGA) machine was used to determine the heat decomposition values in heat resistance testing. Results showed that brake pad with 100 mesh and 10% composition of coconut husk particle showed the highest friction coefficient. For heat resistance, brake pad with 100 mesh and 30% composition of coconut husk dust showed the highest decomposition temperature, due to the high percentage of coconut husk particle in the composition, thus increased the thermal stability. As a comparison, brake pad composed with coconut husk particle showed better heat resistance results than commercial brake pad.

  4. Heat resistance of Alicyclobacillus acidocaldarius in water, various buffers, and orange juice.

    PubMed

    Palop, A; Alvarez, I; Raso, J; Condón, S

    2000-10-01

    The effect of the pH or the composition of the heating medium and of the sporulation temperature on the heat resistance of spores of a thermoacidophilic spore-forming microorganism isolated from a dairy beverage containing orange fruit concentrate was investigated. The species was identified as Alicyclobacillus acidocaldarius. The spores showed the same heat resistance in citrate-phosphate buffers of pH 4 and 7, in distilled water, and in orange juice at any of the temperatures tested (D120 degrees C = 0.1 min and z = 7 degrees C). A raise in 20 degrees C in the sporulation temperature (from 45 to 65 degrees C) increased the heat resistance eightfold (from D110 degrees C = 0.48 min when sporulated at 45 degrees C to 3.9 min when sporulated at 65 degrees C). The z-values remained constant for all sporulation temperatures. The spores of this strain of A. acidocaldarius were very heat resistant and could easily survive any heat treatment currently applied to pasteurize fruit juices. PMID:11041137

  5. Pinning of Austenite Grain Boundaries by

    NASA Astrophysics Data System (ADS)

    Doğan, Ömer N.; Michal, G. M.; Kwon, H.-W.

    1992-08-01

    The growth behavior of austenite grains in the presence of A1N precipitates varies with the temperature and time of anneal. To study this behavior, two iron alloys, (in weight percent) a 0.1 carbon base chemistry with 0.03A1/0.01N and 0.09A1/0.04N, respectively, were annealed between 1000 °C and 1200 °C for times of up to 180 minutes. Using optical microscopy, as many as 1000 austenite grains per heat-treatment condition were measured. Conditions of sup- pressed, abnormal, and uniform grain growth were observed. Using an extraction replica tech- nique, the size, shape, and distribution of the A1N particles were determined using transmission electron microscopy (TEM). The largest grain boundary curvatures calculated, using the Hellman- Hillert pinning model, were in close agreement with independent calculations of curvatures using the grain size data. The largest grains in the lognormal size distribution of austenite grains were found to be the ones with the potential to grow to abnormally large sizes.

  6. [The influence of oil heat treatment on wood decay resistance by Fourier infrared spectrum analysis].

    PubMed

    Wang, Ya-Mei; Ma, Shu-Ling; Feng, Li-Qun

    2014-03-01

    Wood preservative treatment can improve defects of plantation wood such as easy to corrupt and moth eaten. Among them heat-treatment is not only environmental and no pollution, also can improve the corrosion resistance and dimension stability of wood. In this test Poplar and Mongolian Seoteh Pine was treated by soybean oil as heat-conducting medium, and the heat treatment wood was studied for indoor decay resistance; wood chemical components before and after treatment, the effect of heat treatment on wood decay resistance performance and main mechanism of action were analysed by Fourier infrared spectrometric. Results showed that the mass loss rate of poplar fell from 19.37% to 5% and Mongolian Seoteh Pine's fell from 8.23% to 3.15%, so oil heat treatment can effectively improve the decay resistance. Infrared spectrum analysis shows that the heat treatment made wood's hydrophilic groups such as hydroxyl groups in largely reduced, absorbing capacity decreased and the moisture of wood rotting fungi necessary was reduced; during the heat treatment wood chemical components such as cellulose, hemicellu lose were degraded, and the nutrient source of wood rotting fungi growth necessary was reduced. Wood decay fungi can grow in the wood to discredit wood is because of that wood can provide better living conditions for wood decay fungi, such as nutrients, water, oxygen, and so on. The cellulose and hemicellulose in wood is the main nutrition source of wood decay fungi. So the oil heat-treatment can reduce the cellulose, hemicellulose nutrition source of wood decay fungi so as to improve the decay resistance of wood. PMID:25208386

  7. Oxidation resistant alloys, method for producing oxidation resistant alloys

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

  8. Oxidation resistant alloys, method for producing oxidation resistant alloys

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

  9. Heating of solid earthen material, measuring moisture and resistivity

    DOEpatents

    Heath, William O.; Richardson, Richard L.; Goheen, Steven C.

    1994-01-01

    The present invention includes a method of treating solid earthen material having volatile, semi-volatile, and non-volatile contaminants. Six electrodes are inserted into a region of earthen material to be treated in a substantially equilateral hexagonal arrangement. Six phases of voltages are applied to corresponding electrodes. The voltages are adjusted within a first range of voltages to create multiple current paths between pairs of the electrodes. The current paths are evenly distributed throughout the region defined by the electrodes and therefore uniformly heat the region. The region of earthen material is heated to a temperature sufficient to substantially remove volatile and semi-volatile contaminants by promoting microbial action. This temperature is less than a melting temperature of the earthen material.

  10. Heating of solid earthen material, measuring moisture and resistivity

    DOEpatents

    Heath, W.O.; Richardson, R.L.; Goheen, S.C.

    1994-07-19

    The present invention includes a method of treating solid earthen material having volatile, semi-volatile, and non-volatile contaminants. Six electrodes are inserted into a region of earthen material to be treated in a substantially equilateral hexagonal arrangement. Six phases of voltages are applied to corresponding electrodes. The voltages are adjusted within a first range of voltages to create multiple current paths between pairs of the electrodes. The current paths are evenly distributed throughout the region defined by the electrodes and therefore uniformly heat the region. The region of earthen material is heated to a temperature sufficient to substantially remove volatile and semi-volatile contaminants by promoting microbial action. This temperature is less than a melting temperature of the earthen material. 13 figs.

  11. Co-Optimization of Wrought Alumina-Forming Austenitic Stainless Steel Composition Ranges for High-Temperature Creep and Oxidation/Corrosion Resistance

    SciTech Connect

    Brady, Michael P; Magee, John H; Yamamoto, Yukinori; Helmick, David; Wang, Lu

    2014-01-01

    A seriesofcandidatealumina-formingaustenitic(AFA)stainlesssteelsdesignedtoevaluatetheeffectsof variationinAl,C,Cr,Mn,Nb,andNicontentonhigh-temperaturetensileproperties,creep,and oxidation/corrosionresistancewerestudied.ThecompositionsassessedwerebasedonmediumNi (20 25 wt%)andlowNi(12wt%)AFAvariationsstrengthenedprimarilybyMCand/orM23C6 carbide precipitates,andahighNi(32wt%)AFAsuperalloyvariationstrengthenedprimarilyby -Ni3Al intermetallic precipitates.Tensileandcreeppropertiesweremeasuredat650and750/760 1C, oxidation resistance from650to900 1C inairwithwatervaporandsteamenvironments,andsulfidation oxidation resistance inAr 20%H2 20%H2O 5% H2S at550and650 1C. Optimizedcompositionrangesfordifferent use temperaturesrangesbasedontheseevaluationsarepresented.

  12. Experimental study on heat transfer and flow resistance in improved latticework cooling channels

    NASA Astrophysics Data System (ADS)

    Deng, Hongwu; Wang, Kai; Zhu, Jianqin; Pan, Wenyan

    2013-06-01

    Characteristics of heat transfer and flow resistance of the latticework (vortex) cooling channel with ribs truncated at their two ends were theoretically and experimentally studied compared with regular and smooth channels of the same configuration. The results showed: the heat transfer efficiency of the latticework channel with two slots was better than those of regular and smooth channels of the same configuration, its flow resistance situation in the slotted channel becomes quite complex; The flow resistances of 2 mm- and 4 mm-slotted channels were obviously lower than that of the regular channel, but they are still much higher than that of the smooth channel; Compared with the regular channel, the total heat transfer efficiencies of the slotted channels were pretty improved, among them the 4-mm slotted channel has the biggest enhancement. From the experimental results, it is obvious that the latticework channel with proper slots has a great prospect in the design of the inner cooling channels of turbine blades.

  13. Comparison of Direct Solar Energy to Resistance Heating for Carbothermal Reduction of Regolith

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony C.; Gustafson, Robert J.

    2011-01-01

    A comparison of two methods of delivering thermal energy to regolith for the carbo thermal reduction process has been performed. The comparison concludes that electrical resistance heating is superior to direct solar energy via solar concentrators for the following reasons: (1) the resistance heating method can process approximately 12 times as much regolith using the same amount of thermal energy as the direct solar energy method because of superior thermal insulation; (2) the resistance heating method is more adaptable to nearer-term robotic exploration precursor missions because it does not require a solar concentrator system; (3) crucible-based methods are more easily adapted to separation of iron metal and glass by-products than direct solar energy because the melt can be poured directly after processing instead of being remelted; and (4) even with projected improvements in the mass of solar concentrators, projected photovoltaic system masses are expected to be even lower.

  14. Alumina-Forming Austenitic Stainless Steels Strengthened by Laves Phase and MC Carbide Precipitates

    NASA Astrophysics Data System (ADS)

    Yamamoto, Y.; Brady, M. P.; Lu, Z. P.; Liu, C. T.; Takeyama, M.; Maziasz, P. J.; Pint, B. A.

    2007-11-01

    Creep strengthening of Al-modified austenitic stainless steels by MC carbides or Fe2Nb Laves phase was explored. Fe-20Cr-15Ni-(0-8)Al and Fe-15Cr-20Ni-5Al base alloys (at. pct) with small additions of Nb, Mo, W, Ti, V, C, and B were cast, thermally-processed, and aged. On exposure from 650 °C to 800 °C in air and in air with 10 pct water vapor, the alloys exhibited continuous protective Al2O3 scale formation at an Al level of only 5 at. pct (2.4 wt pct). Matrices of the Fe-20Cr-15Ni-5Al base alloys consisted of γ (fcc) + α (bcc) dual phase due to the strong α-Fe stabilizing effect of the Al addition and exhibited poor creep resistance. However, adjustment of composition to the Fe-15Cr-20Ni-5Al base resulted in alloys that were single-phase γ-Fe and still capable of alumina scale formation. Alloys that relied solely on Fe2Nb Laves phase precipitates for strengthening exhibited relatively low creep resistance, while alloys that also contained MC carbide precipitates exhibited creep resistance comparable to that of commercially available heat-resistant austenitic stainless steels. Phase equilibria studies indicated that NbC precipitates in combination with Fe2Nb were of limited benefit to creep resistance due to the solution limit of NbC within the γ-Fe matrix of the alloys studied. However, when combined with other MC-type strengtheners, such as V4C3 or TiC, higher levels of creep resistance were obtained.

  15. HNS/Teflon, a new heat resistant explosive

    NASA Technical Reports Server (NTRS)

    Heller, H.; Bertram, A. L.

    1973-01-01

    HNS/Teflon (90/10) is a new pressed explosive developed for use in the Apollo program. The major advantages of HNS/Teflon are (1) excellent thermal stability at elevated temperatures, (2) superior resistance to sublimation at high temperatures and low pressures and (3) ease of molding powder preparation, pressing and machining. The impact sensitivity of HNS/Teflon is between that of Comp B and Comp A-3 while its explosive performance is about the same as TNT. Under the severe environmental conditions of the moon's surface, this explosive successfully performed its intended function of generating seismic waves in the Apollo ALSEP and LSPE experiments. (Modified author abstract)

  16. Heating of solid earthen material, measuring moisture and resistivity

    DOEpatents

    Heath, William O.; Gauglitz, Phillip A.; Pillay, Gautam; Bergsman, Theresa M.; Eschbach, Eugene A.; Goheen, Steven C.; Richardson, Richard L.; Roberts, Janet S.; Schalla, Ronald

    1996-01-01

    The present invention includes a method of treating solid earthen material having volatile, semi-volatile, and non-volatile contaminants that utilizes electrical energy. A plurality of electrodes are inserted into a region of earthen material to be treated in a selected geometric pattern. Varying phase and voltages configurations are applied to corresponding electrodes to achieve heating, physical phase changes, and the placement of substances within the treatment region. Additionally, treatment mediums can be added to either treat the contamination within the soil or to restrict their mobility.

  17. Heating of solid earthen material, measuring moisture and resistivity

    DOEpatents

    Heath, W.O.; Gauglitz, P.A.; Pillay, G.; Bergsman, T.M.; Eschbach, E.A.; Goheen, S.C.; Richardson, R.L.; Roberts, J.S.; Schalla, R.

    1996-08-13

    The present invention includes a method of treating solid earthen material having volatile, semi-volatile, and non-volatile contaminants that utilizes electrical energy. A plurality of electrodes are inserted into a region of earthen material to be treated in a selected geometric pattern. Varying phase and voltages configurations are applied to corresponding electrodes to achieve heating, physical phase changes, and the placement of substances within the treatment region. Additionally, treatment mediums can be added to either treat the contamination within the soil or to restrict their mobility. 29 figs.

  18. Study on modeling of resist heating effect correction in EB mask writer EBM-9000

    NASA Astrophysics Data System (ADS)

    Nomura, Haruyuki; Kamikubo, Takashi; Suganuma, Mizuna; Kato, Yasuo; Yashima, Jun; Nakayamada, Noriaki; Anze, Hirohito; Ogasawara, Munehiro

    2015-07-01

    Resist heating effect which is caused in electron beam lithography by rise in substrate temperature of a few tens or hundreds of degrees changes resist sensitivity and leads to degradation of local critical dimension uniformity (LCDU). Increasing writing pass count and reducing dose per pass is one way to avoid the resist heating effect, but it worsens writing throughput. As an alternative way, NuFlare Technology is developing a heating effect correction system which corrects CD deviation induced by resist heating effect and mitigates LCDU degradation even in high dose per pass conditions. Our developing correction model is based on a dose modulation method. Therefore, a kind of conversion equation to modify the dose corresponding to CD change by temperature rise is necessary. For this purpose, a CD variation model depending on local pattern density was introduced and its validity was confirmed by experiments and temperature simulations. And then the dose modulation rate which is a parameter to be used in the heating effect correction system was defined as ideally irrelevant to the local pattern density, and the actual values were also determined with the experimental results for several resist types. The accuracy of the heating effect correction was also discussed. Even when deviations depending on the pattern density slightly remains in the dose modulation rates (i.e., not ideal in actual), the estimated residual errors in the correction are sufficiently small and acceptable for practical 2 pass writing with the constant dose modulation rates. In these results, it is demonstrated that the CD variation model is effective for the heating effect correction system.

  19. Dry-heat resistance of selected psychrophiles. [Viking lander in spacecraft sterilization

    NASA Technical Reports Server (NTRS)

    Winans, L.; Pflug, I. J.; Foster, T. L.

    1977-01-01

    The dry-heat resistance characteristics of spores of psychrophilic organisms isolated from soil samples from the Viking spacecraft assembly areas at Cape Kennedy Space Flight Center, Cape Canaveral, Fla., were studied. Spore suspensions were produced, and dry-heat D values were determined for the microorganisms that demonstrated growth or survival under a simulated Martian environment. The dry-heat tests were carried out by using the planchet-boat-hot plate system at 110 and 125 C with an ambient relative humidity of 50% at 22 C. The spores evaluated had a relatively low resistance to dry heat. D (110 C) values ranged from 7.5 to 122 min, whereas the D (125 C) values ranged from less than 1.0 to 9.8 min.

  20. Investigations of temperature dependences of electrical resistivity and specific heat capacity of metals

    NASA Astrophysics Data System (ADS)

    Eser, Erhan; Koç, Hüseyin

    2016-07-01

    In this study, we calculated the electrical resistivity and heat capacities of some ideal metals (Cu, Pt, and Pd) using a method that it employs the statistical model and Debye functions. The method is used to provide a simple and reliable analytical procedure for wide temperature range. The results obtained for the electrical resistivity and heat capacity have been compared with the results in literature. The results obtained at low temperature are in excellent agreement with experimental and theoretical results. Finally the used approximation and analytical method are a useful approach to calculate thermophysical properties of metals.

  1. Electrical resistivity and specific heat of La 2-XSr XNiO 4+δ

    NASA Astrophysics Data System (ADS)

    Matsushita, Akiyuki; Matsumoto, Takehiko; Takayanagi, Shigeru; Mōri, Nobuo

    1990-08-01

    Specific heat and electrical resistivity were measured on La 2-XSr XNiO 4+δ with various Sr concentrations as a function of temerature. The behaviors of electrical resistivity and lattice constants show a marked change at X⋃0.5 (Xc). The specific heat shows a hump at about 6K in C/T vs. T 2 plot for all of samples annealed in air. For the samples annealed in hydrogen no hump is observed. The relationship between Xc and interstitial oxygen defect is discussed.

  2. Resistively Heated SiC Nozzle for Generating Molecular Beams

    NASA Technical Reports Server (NTRS)

    Cagiano, Steven; Abell, Robert; Patrick, Edward; Bendt, Miri; Gundersen, Cynthia

    2007-01-01

    An improved nozzle has been developed to replace nozzles used previously in an apparatus that generates a substantially unidirectional beam of molecules passing through a vacuum at speeds of several kilometers per second. The basic principle of operation of the apparatus is the same for both the previous and the present nozzle designs. The main working part of the nozzle is essentially a cylinder that is closed except that there is an inlet for a pressurized gas and, at one end, the cylinder is closed by a disk that contains a narrow central hole that serves as an outlet. The cylinder is heated to increase the thermal speeds of the gas molecules into the desired high-speed range. Heated, pressurized gas escapes through the outlet into a portion of the vacuum chamber that is separated, by a wall, from the rest of the vacuum chamber. In this portion of the vacuum chamber, the gas undergoes a free jet expansion. Most of the expanded gas is evacuated and thus does not become part of the molecular beam. A small fraction of the expanded beam passes through a narrow central orifice in the wall and thereby becomes a needle- thin molecular beam in the portion of the vacuum on the downstream side of the wall.

  3. Origin of Self-preservation Effect for Hydrate Decomposition: Coupling of Mass and Heat Transfer Resistances.

    PubMed

    Bai, Dongsheng; Zhang, Diwei; Zhang, Xianren; Chen, Guangjin

    2015-01-01

    Gas hydrates could show an unexpected high stability at conditions out of thermodynamic equilibrium, which is called the self-preservation effect. The mechanism of the effect for methane hydrates is here investigated via molecular dynamics simulations, in which an NVT/E method is introduced to represent different levels of heat transfer resistance. Our simulations suggest a coupling between the mass transfer resistance and heat transfer resistance as the driving mechanism for self-preservation effect. We found that the hydrate is initially melted from the interface, and then a solid-like water layer with temperature-dependent structures is formed next to the hydrate interface that exhibits fractal feature, followed by an increase of mass transfer resistance for the diffusion of methane from hydrate region. Furthermore, our results indicate that heat transfer resistance is a more fundamental factor, since it facilitates the formation of the solid-like layer and hence inhibits the further dissociation of the hydrates. The self-preservation effect is found to be enhanced with the increase of pressure and particularly the decrease of temperature. Kinetic equations based on heat balance calculations is also developed to describe the self-preservation effect, which reproduces our simulation results well and provides an association between microscopic and macroscopic properties. PMID:26423519

  4. Origin of Self-preservation Effect for Hydrate Decomposition: Coupling of Mass and Heat Transfer Resistances

    PubMed Central

    Bai, Dongsheng; Zhang, Diwei; Zhang, Xianren; Chen, Guangjin

    2015-01-01

    Gas hydrates could show an unexpected high stability at conditions out of thermodynamic equilibrium, which is called the self-preservation effect. The mechanism of the effect for methane hydrates is here investigated via molecular dynamics simulations, in which an NVT/E method is introduced to represent different levels of heat transfer resistance. Our simulations suggest a coupling between the mass transfer resistance and heat transfer resistance as the driving mechanism for self-preservation effect. We found that the hydrate is initially melted from the interface, and then a solid-like water layer with temperature-dependent structures is formed next to the hydrate interface that exhibits fractal feature, followed by an increase of mass transfer resistance for the diffusion of methane from hydrate region. Furthermore, our results indicate that heat transfer resistance is a more fundamental factor, since it facilitates the formation of the solid-like layer and hence inhibits the further dissociation of the hydrates. The self-preservation effect is found to be enhanced with the increase of pressure and particularly the decrease of temperature. Kinetic equations based on heat balance calculations is also developed to describe the self-preservation effect, which reproduces our simulation results well and provides an association between microscopic and macroscopic properties. PMID:26423519

  5. Hot Hydroforming of 22MnB5 Tube by Resistance Heating

    NASA Astrophysics Data System (ADS)

    Chu, G. N.; Lin, Y. L.; Ding, M. Q.

    2016-05-01

    To promote the application of high strength steels in automobile bodies, the practicability of hot hydroforming of tube by resistance heating is illustrated. From the results of experiments conducted to measure temperature distributions of the tube during the forming process, a method to improve temperature uniformity has been proposed and achieved. Validity was evaluated by examining the effects of hot gas forming on the microstructure and hardness. Results indicate an obvious temperature difference along the axial direction for two cross-sectional shapes: the temperature in the middle zone of the tube is higher than that at its ends. Both thermal convection and cross-sectional shape have only a limited effect on the temperature distribution. The main reason for non-uniform temperature distribution is the heat transition between the electrodes and the tube ends. The temperature difference decreased as the heating rate increased. In contrast, the temperature distribution was even along the circumferential direction for both cross-sectional shapes. Adjusting the contact resistance is a useful method of reducing the temperature difference. In this study, the temperature difference was successfully decreased to 20°C, while reaching a maximum temperature of 750°C, which is adequate for both forming and quenching. A rectangular component was formed to validate the practicality and efficiency of tube hot hydroforming by resistance heating. The hardness and microstructure met the requirements of 22MnB5, which demonstrates both the forming efficiency and quantity advantages of hot gas hydroforming by resistance heating.

  6. Hot Hydroforming of 22MnB5 Tube by Resistance Heating

    NASA Astrophysics Data System (ADS)

    Chu, G. N.; Lin, Y. L.; Ding, M. Q.

    2016-07-01

    To promote the application of high strength steels in automobile bodies, the practicability of hot hydroforming of tube by resistance heating is illustrated. From the results of experiments conducted to measure temperature distributions of the tube during the forming process, a method to improve temperature uniformity has been proposed and achieved. Validity was evaluated by examining the effects of hot gas forming on the microstructure and hardness. Results indicate an obvious temperature difference along the axial direction for two cross-sectional shapes: the temperature in the middle zone of the tube is higher than that at its ends. Both thermal convection and cross-sectional shape have only a limited effect on the temperature distribution. The main reason for non-uniform temperature distribution is the heat transition between the electrodes and the tube ends. The temperature difference decreased as the heating rate increased. In contrast, the temperature distribution was even along the circumferential direction for both cross-sectional shapes. Adjusting the contact resistance is a useful method of reducing the temperature difference. In this study, the temperature difference was successfully decreased to 20°C, while reaching a maximum temperature of 750°C, which is adequate for both forming and quenching. A rectangular component was formed to validate the practicality and efficiency of tube hot hydroforming by resistance heating. The hardness and microstructure met the requirements of 22MnB5, which demonstrates both the forming efficiency and quantity advantages of hot gas hydroforming by resistance heating.

  7. Effect of chemical heat treatment on the fatigue resistance of titanium alloys

    SciTech Connect

    Matokhnyuk, L.E.; Nochovnaya, N.A.; Voinalovich, A.V.; Yakovleva, T.Y.

    1985-11-01

    In order to improve the wear resistance of titanium alloy articles, chemical heat treatment, in particular, oxidation and nitriding diffusion impregnation of the article is performed. As a result of this treatment there is a marked increase in surface layer hardness. The change in structure and properties of surface layers have a marked effect on material resistance in fatigue failure as well as on sensitivity to stress concentration. This is the subject of the research discussed here.

  8. Corrosion of austenitic alloys in aerated brines

    SciTech Connect

    Heidersbach, R.; Shi, A.; Sharp, S.

    1999-11-01

    This report discusses the results of corrosion exposures of three austenitic alloys--3l6L stainless steel, UNS N10276, and UNS N08367. Coupons of these alloys were suspended in a series of brines used for processing in the pharmaceutical industry. The effects of surface finish and welding processes on the corrosion behavior of these alloys were determined. The 316L coupons experienced corrosion in several environments, but the other alloys were unaffected during the one-month exposures of this investigation. Electropolishing the surfaces improved corrosion resistance.

  9. Heat treatment effect on microstructure, hardness and wear resistance of Cr26 white cast iron

    NASA Astrophysics Data System (ADS)

    Zhou, Shaoping; Shen, Yehui; Zhang, Hao; Chen, Dequan

    2015-01-01

    High chromium cast iron(HCCI) is taken as material of coal water slurry pump impeller, but it is susceptible to produce serious abrasive wear and erosion wear because of souring of hard coal particles. The research on optimization of heat treatments to improve abrasive wear properties of HCCI is insufficient, so effect of heat treatments on the microstructure, hardness, toughness, and wear resistance of Cr26 HCCI is investigated to determine the optimal heat treatment process for HCCI. A series of heat treatments are employed. The microstructures of HCCI specimens are examined by using optical microscopy and scanning electron microscopy. The hardness and impact fracture toughness of as-cast and heat treated specimens are measured. The wear tests are assessed by a Type M200 ring-on block wear tester. The results show the following: With increase of the quenching temperature from 950 °C to 1050 °C, the hardness of Cr26 HCCI increased to a certain value, kept for a time and then decreased. The optimal heat treatment process is 2 h quenching treatment at 1000 °C, followed by a subsequent 2 h tempering at 400 °C. The hardness of HCCI is related to the precipitation and redissolution of secondary carbides in the process of heat treatment. The subsequent tempering treatment would result in a slight decrease of hardness but increase of toughness. The wear resistance is much related to the "supporting" effect of the matrix and the "protective" effect of the hard carbide embedded in the matrix, and the wear resistance is further dependent on the hardness and the toughness of the matrix. This research can provide an important insight on developing an optimized heat treatment method to improve the wear resistance of HCCI.

  10. 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.

  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. Effect of pH on Thermoanaerobacterium thermosaccharolyticum DSM 571 growth, spore heat resistance and recovery.

    PubMed

    Mtimet, Narjes; Guégan, Stéphanie; Durand, Lucile; Mathot, Anne-Gabrielle; Venaille, Laurent; Leguérinel, Ivan; Coroller, Louis; Couvert, Olivier

    2016-05-01

    Thermophilic spore-forming bacteria are potential contaminants in several industrial sectors involving high temperatures (40-65 °C) in the manufacturing process. Among those thermophilic spore-forming bacteria, Thermoanaerobacterium thermosaccharolyticum, called "the swelling canned food spoiler", has generated interest over the last decade in the food sector. The aim of this study was to investigate and to model pH effect on growth, heat resistance and recovery abilities after a heat-treatment of T. thermosaccharolyticum DSM 571. Growth and sporulation were conducted on reinforced clostridium media and liver broth respectively. The highest spore heat resistances and the greatest recovery ability after a heat-treatment were obtained at pH condition allowing maximal growth rate. Growth and sporulation boundaries were estimated, then models using growth limits as main parameters were extended to describe and quantify the effect of pH on recovery of injured spores after a heat-treatment. So, cardinal values were used as a single set of parameters to describe growth, sporulation and recovery abilities. Besides, this work suggests that T. thermosaccharolyticum preserve its ability for germination and outgrowth after a heat-treatment at a low pH where other high resistant spore-forming bacteria like Geobacillus stearothermophilus are unable to grow. PMID:26742617

  13. A thermal plasmonic sensor platform: resistive heating of nanohole arrays.

    PubMed

    Virk, Mudassar; Xiong, Kunli; Svedendahl, Mikael; Käll, Mikael; Dahlin, Andreas B

    2014-06-11

    We have created a simple and efficient thermal plasmonic sensor platform by letting a DC current heat plasmonic nanohole arrays. The sensor can be used to determine thermodynamic parameters in addition to monitoring molecular reactions in real-time. As an application example, we use the thermal sensor to determine the kinetics and activation energy for desorption of thiol monolayers on gold. Further, the temperature of the metal can be measured optically by the spectral shift of the bonding surface plasmon mode (0.015 nm/K). We show that this resonance shift is caused by thermal lattice expansion, which reduces the plasma frequency of the metal. The sensor is also used to determine the thin film thermal expansion coefficient through a theoretical model for the expected resonance shift. PMID:24807397

  14. Keeping cool on the job. [Heat-resistant protective clothing

    SciTech Connect

    Lihach, N.; O'Brien, J.

    1982-09-01

    Maintenance workers at nuclear power plants need special protective clothing that slows overheating from the 55/sup 0/C temperature caused by waste heat from pipes and pressure vehicles. Cooling garments increase efficiency by extending the time workers can function, as well as safeguarding their health and morale. The Electric Power Research Institute evaluated two cooling concepts: circulating liquid suits already available on the market and a prototype frozen-water garment. Performance tests of the frozen-water suit found that it can more than double the 65-minute stay-time of liquid-cooled systems. The frozen-water garment permits mobility, is compatible with radiation protection and other garments and equipment, is easty to clean or decontaminate, has no moving parts, and is attractively priced. 4 figures. (DCK)

  15. Monitoring six-phase ohmic heating of contaminated soils using electrical resistance tomography

    SciTech Connect

    Ramirez, A.L.; Daily, W.D.

    1994-09-01

    Electrical resistance tomography (ERT) was used to monitor six-phase ohmic heating used for the insitu remediation of volatile organic compounds from subsurface water and soil at the Savannah River Site, near Aiken, South Carolina. The changes in electrical conductivity caused by six-phase ohmic-heating in a clay layer located in the vadose zone were monitored during a period of approximately 2 months, before, during and after heating. From an array of electrodes located in 4 boreholes, we collected electrical resistivity data between five pairs of adjacent holes pairs. This data was used to calculate tomographs which showed the electrical conductivity changes along five vertical planes. The difference tomographs show the combined effects of moisture redistribution and heating caused by six-phase heating and vapor extraction. The tomographs show that most of the clay layer increased in electrical conductivity during the first 3 weeks of the 4 week long heating phase. At this time, the electrical conductivities near the center of the heating array were twice as large as the pre-heat conductivities. Then the electrical conductivity started to decrease for portions of the clay layer closest to the vapor extraction well. We propose that the conductivity decreases are due to the removal of moisture by the heating and vacuum extraction. Parts of the clay layer near the extraction well reached electrical conductivities as low as 40% of the pre-heating values. We propose that these regions of lower than ambient electrical conductivities are indicators of regions where the vapor removal by vacuum extraction was most effective. At the end of the heating phase, our estimates suggest that the clay saturation may have dropped to as low as 10% based on the observed conductivity changes.

  16. Corrosion performance of laser-welded austenitic-ferritic connections

    NASA Astrophysics Data System (ADS)

    Weigl, M.; Schmidt, M.

    2013-02-01

    In order to reduce the material costs of white-goods made of stainless steels, tailored constructions with unequally alloyed stainless steels shall be used. For that purpose nickel-alloyed austenitic stainless steels are supposed to be limited to zones with demanding needs for corrosions resistance, whereas nickel-free ferritic stainless steels provide an attractive cost-performance ratio for the remaining components of a system. Particularly the present article discusses the corrosion performance of austenitic-ferritic connections, welded with high-power disc lasers at accelerated feed rates, as a function of the shielding gas composition and the surface condition.

  17. Hardenability of austenite in a dual-phase steel

    SciTech Connect

    Sarwar, M.; Priestner, R.

    1999-06-01

    A low-carbon, low-alloy steel was intercritically heat treated and thermomechanically processed to study the martensitic hardenability of austenite present. Rolling of the two-phase ({alpha} + {gamma}) microstructure elongated austenite particles and reduced their martensitic hardenability because the {alpha}/{gamma} interface where new ferrite forms during cooling was increased by the particle elongation. The martensite particles obtained in rolled material were also elongated or fibered in the rolling direction. Therefore, the thermomechanical processing of a two-phase ({alpha} + {gamma}) mixture has the detrimental effect of increasing the quenching power needed to yield a specific amount of martensite.

  18. Examination of carbon partitioning into austenite during tempering of bainite

    SciTech Connect

    Clarke, Amy J; Caballero, Francisca G; Miller, Michael K; Garcia - Mateo, C

    2010-01-01

    The redistribution of carbon after tempering of a novel nanocrystalline bainitic steel consisting of a mixture of supersaturated ferrite and retained austenite, has been analyzed by atom probe tomography. Direct supporting evidence of additional austenite carbon enrichment beyond that initially achieved during the bainite heat treatment was not obtained during subsequent tempering of this high carbon, high silicon steel. Evidence of competing reactions during tempering, such as the formation of carbon clusters in bainitic ferrite that signify the onset of the transitional carbides precipitation, was observed.

  19. Incidence and Diversity of Potentially Highly Heat-Resistant Spores Isolated at Dairy Farms

    PubMed Central

    Scheldeman, Patsy; Pil, Annelies; Herman, Lieve; De Vos, Paul; Heyndrickx, Marc

    2005-01-01

    The presence of highly heat-resistant spores of Bacillus sporothermodurans in ultrahigh-temperature or sterilized consumer milk has emerged as an important item in the dairy industry. Their presence is considered undesirable since they hamper the achievement of commercial sterility requirements. By using a selective 30-min heat treatment at 100°C, 17 Belgian dairy farms were screened to evaluate the presence, sources, and nature of potentially highly heat-resistant spores in raw milk. High numbers of these spores were detected in the filter cloth of the milking equipment and in green crop and fodder samples. About 700 strains were isolated after the selective heating, of which 635 could be screened by fatty acid methyl ester analysis. Representative strains were subjected to amplified ribosomal DNA restriction analysis, 16S rRNA gene sequencing, percent G+C content, and DNA-DNA reassociations for further identification. The strain collection showed a remarkable diversity, with representatives of seven aerobic spore-forming genera. Bacillus licheniformis and Bacillus pallidus were the most predominant species overall. Twenty-three percent of the 603 spore-forming isolates proved to belong to 18 separate novel species. These findings suggest that the selective heating revealed a pool of unknown organisms with a higher heat-resistant character. This study showed that high spore counts can occur at the dairy farm and that feed and milking equipment can act as reservoirs or entry points for potentially highly heat-resistant spores into raw milk. Lowering this spore load by good hygienic measures could probably further reduce the contamination level of raw milk, in this way minimizing the aerobic spore-forming bacteria that could lead to spoilage of milk and dairy products. Assessment and characterization of this particular flora are of great importance to allow the dairy or food industry to adequately deal with newly arising microbiological problems. PMID:15746351

  20. Heat resistance of dermatophyte's conidiospores from athletes kits stored in Nigerian University Sport's Center.

    PubMed

    Essien, J P; Jonah, I; Umoh, A A; Eduok, S I; Akpan, E J; Umoiyoho, A

    2009-03-01

    The incidence and heat resistance of conidiospores produced by dermatophytes isolated from athlete's kits (canvasses, stockings and spike shoes) stored in Nigerian University Sport's Centre were investigated. Epidermophyton floccosum, Microsporum oudouinii, Microsporum canis, Trichophyton concentricum, Trichophyton mentagrophytes and Trichophyton rubrum were isolated and their incidence on the athlete's kits varied with the species and type of kits. Among the isolates T. mentagrophytes, T. rubrum and E. floccosum with 25%, 23% and 20% prevalence rates respectively, were the most common isolates, and are often associated with tinea pedis (athletes foot). Canvasses with the highest incidence of dermatophytes (25 out of 34 fungal isolates) were the most contaminated kits and could serve as effective articles for the transmission of tinea pedis among athletes in Nigeria. The common etiological agents screened, produced asexual spores (conidiospores) that exhibited high resistance to heat treatment at 80 degrees C. Of the three isolates, E. floccosum, with a decimal reduction time (D-value) of D80 = 4.4 min was the most resistant followed by T. mentagrophytes with D80 = 4.0 min and then T. rubrum with D80 = 3.2 min. The spores elimination pattern indicates that increasing the heating duration would decrease the decimal reduction time and possibly denature the fungal propagules but may damage the skin during treatment with hot water compresses. The findings have shown that the use of hot water compresses is palliative but heat treatment especially vapour-heat treatment offers adequate preventive measures if applied for periodic treatment of contaminated kits. However, determining the correct condition for effective decontamination will require detailed understanding of the heat resistance of fungal spores. Otherwise treatment of kits with detergent and chaotropic agent such as urea and guanidinium salt is preferred to heat treatment. PMID:19388558

  1. The effect of mechanical surface and heat treatments on the erosion resistance of 6061 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D.; Brainard, W. A.

    1981-01-01

    The effects of both mechanical surface treatments and heat treatments on the erosion resistance of 6061 aluminum alloy were studied in order to gain a better understanding of material properties which affect erosion behavior. It was found that mechanical surface treatments have little or no effect on the erosion resistance. This is due to the formation by particle impact of a work-hardened surface layer, independent of the initial surface condition. The erosion resistance of aluminum single crystals was found to be independent of orientation, which is due to destruction of the surface microstructure and formation of a polycrystalline surface layer by the particle impact as observed by X-ray diffraction. Although on solution treatment of annealed aluminum 6061 the increase in hardness is accompanied by an increase in erosion resistance, precipitation treatment (which causes a further increase in hardness) results in a slightly lower erosion resistance.

  2. Integrated Thermal Protection Systems and Heat Resistant Structures

    NASA Technical Reports Server (NTRS)

    Pichon, Thierry; Lacoste, Marc; Barreteau, R.; Glass, David E.

    2006-01-01

    In the early stages of NASA's Exploration Initiative, Snecma Propulsion Solide was funded under the Exploration Systems Research & Technology program to develop a CMC heatshield, a deployable decelerator, and an ablative heat shield for reentry vehicles. Due to changes within NASA's Exploration Initiative, this task was cancelled in early FY06. This paper will give an overview of the work that was accomplished prior to cancellation. The Snecma team consisted of MT Aerospace, Germany, and Materials Research & Design (MR&D), NASA Langley, NASA Dryden, and NASA Ames in the United States. An Apollo-type capsule was chosen as the reference vehicle for the work. NASA Langley generated the trajectory and aerothermal loads. Snecma and MT Aerospace began the design of a ceramic aft heatshield (CAS) utilizing C/SiC panels as the capsule heatshield. MR&D led the design of a C/SiC deployable decelerator, NASA Ames led the characterization of several ablators, NASA Dryden led the development of a heath management system and the high temperature structures testing, and NASA Langley led the insulation characterization. Though the task was pre-maturely cancelled, a significant quantity of work was accomplished.

  3. Correlation between mechanical properties and retained austenite characteristics in a low-carbon medium manganese alloyed steel plate

    SciTech Connect

    Chen, Jun; Lv, Mengyang; Tang, Shuai; Liu, Zhenyu; Wang, Guodong

    2015-08-15

    The effects of retained austenite characteristics on tensile properties and low-temperature impact toughness have been investigated by means of transmission electron microscopy and X-ray diffraction. It was found that only part of austenite phase formed during heat treating was left at room temperature. Moreover, the film-like retained austenite is displayed between bcc-martensite laths after heat treating at 600 °C, while the block-form retained austenite with thin hcp-martensite laths is observed after heat treating at 650 °C. It has been demonstrated that the film-like retained austenite possesses relatively high thermal and mechanical stability, and it can greatly improve low-temperature impact toughness, but its contribution to strain hardening capacity is limited. However, the block-form retained austenite can greatly enhance ultimate tensile strength and strain hardening capacity, but its contribution to low-temperature impact toughness is poor. - Highlights: • Correlation between retained austenite and impact toughness was elucidated. • The impact toughness is related to mechanical stability of retained austenite. • The effect of retained austenite on tensile and impact properties is inconsistent.

  4. Analysis of the Loss in Heat and Acid Resistance during Germination of Spores of Bacillus Species

    PubMed Central

    Luu, Stephanie

    2014-01-01

    A major event in the nutrient germination of spores of Bacillus species is release of the spores' large depot of dipicolinic acid (DPA). This event is preceded by both commitment, in which spores continue through germination even if germinants are removed, and loss of spore heat resistance. The latter event is puzzling, since spore heat resistance is due largely to core water content, which does not change until DPA is released during germination. We now find that for spores of two Bacillus species, the early loss in heat resistance during germination is most likely due to release of committed spores' DPA at temperatures not lethal for dormant spores. Loss in spore acid resistance during germination also paralleled commitment and was also associated with the release of DPA from committed spores at acid concentrations not lethal for dormant spores. These observations plus previous findings that DPA release during germination is preceded by a significant release of spore core cations suggest that there is a significant change in spore inner membrane permeability at commitment. Presumably, this altered membrane cannot retain DPA during heat or acid treatments innocuous for dormant spores, resulting in DPA-less spores that are rapidly killed. PMID:24563034

  5. The Use of Mixed Tocopherols to Improve UV and Heat Resistance of Leather

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most leather products are constantly exposed to outdoor environments, therefore UV and heat resistance are very important qualities, particularly for non-chrome-tanned (chrome-free) leather. In recent years, we have addressed this problem and focused on an environmentally friendly finishing process...

  6. Reduction of Ag–Si electrical contact resistance by selective RF heating

    NASA Astrophysics Data System (ADS)

    de Wijs, W.-J. A.; Ljevar, S.; van de Sande, M. J.; de With, G.

    2016-06-01

    Fast and selective inductive heating of pre-sintered silver lines on silicon as present in solar cells using 27 MHz radio-frequency inductive fields is shown. IR measurements of silicon substrates show that above 450 °C the heating rate of the samples increases sharply, indicating that both the silver and the silicon are heated. By moving the substrate with respect to the RF antenna and modulation of the RF field, silicon wafers were heated reproducibly above 450 °C with heating rates in excess of 200 °C s‑1. Furthermore, selective heating of lines of pre-sintered silver paste was shown below the 450 °C threshold on silicon substrates. The orientation of the silver tracks relative to the RF antenna appeared to be crucial for homogeneity of heating. Transmission line measurements show a clear effect on contact formation between the silver lines and the silicon substrate. To lower the contact resistance sufficiently for industrial feasibility, a high temperature difference between the Si substrate and the Ag tracks is required. The present RF heating process does not match the time scale needed for contact formation between silver and silicon sufficiently, but the significantly improved process control achieved shows promise for applications requiring fast heating and cooling rates.

  7. Development of Rapid Pipe Moulding Process for Carbon Fiber Reinforced Thermoplastics by Direct Resistance Heating

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuto; Harada, Ryuki; Uemura, Toshiki; Katayama, Tsutao; Kuwahara, Hideyuki

    To deal with environmental issues, the gasoline mileage of passenger cars can be improved by reduction of the car weight. The use of car components made of Carbon Fiber Reinforced Plastics (CFRP) is increasing because of its superior mechanical properties and relatively low density. Many vehicle structural parts are pipe-shaped, such as suspension arms, torsion beams, door guard bars and impact beams. A reduction of the car weight is expected by using CFRP for these parts. Especially, when considering the recyclability and ease of production, Carbon Fiber Reinforced Thermoplastics are a prime candidate. On the other hand, the moulding process of CFRTP pipes for mass production has not been well established yet. For this pipe moulding process an induction heating method has been investigated already, however, this method requires a complicated coil system. To reduce the production cost, another system without such complicated equipment is to be developed. In this study, the pipe moulding process of CFRTP using direct resistance heating was developed. This heating method heats up the mould by Joule heating using skin effect of high-frequency current. The direct resistance heating method is desirable from a cost perspective, because this method can heat the mould directly without using any coils. Formerly developed Non-woven Stitched Multi-axial Cloth (NSMC) was used as semi-product material. NSMC is very suitable for the lamination process due to the fact that non-crimp stitched carbon fiber of [0°/+45°/90°/-45°] and polyamide 6 non-woven fabric are stitched to one sheet, resulting in a short production cycle time. The use of the pipe moulding process with the direct resistance heating method in combination with the NSMC, has resulted in the successful moulding of a CFRTP pipe of 300 mm in length, 40 mm in diameter and 2 mm in thickness.

  8. Correction of resist heating effect on variable shaped beam mask writer

    NASA Astrophysics Data System (ADS)

    Nakayamada, Noriaki; Suganuma, Mizuna; Nomura, Haruyuki; Kato, Yasuo; Kamikubo, Takashi; Ogasawara, Munehiro; Zable, Harold; Masuda, Yukihiro; Fujimura, Aki

    2016-04-01

    The specifications for critical dimension (CD) accuracy and line edge roughness are getting tighter to promote every photomask manufacturer to choose electron beam resists of lower sensitivity. When the resist is exposed by too many electrons, it is excessively heated up to have higher sensitivity at a higher temperature, which results in degraded CD uniformity. This effect is called "resist heating effect" and is now the most critical error source in CD control on a variable shaped beam (VSB) mask writer. We have developed an on-tool, real-time correction system for the resist heating effect. The system is composed of correction software based on a simple thermal diffusion model and computational hardware equipped with more than 100 graphical processing unit chips. We have demonstrated that the designed correction accuracy was obtained and the runtime of correction was sufficiently shorter than the writing time. The system is ready to be deployed for our VSB mask writers to retain the writing time as short as possible for lower sensitivity resists by removing the need for increased pass count.

  9. Heat Resistant Characteristics of Major Royal Jelly Protein 1 (MRJP1) Oligomer

    PubMed Central

    Moriyama, Takanori; Ito, Aimi; Omote, Sumire; Miura, Yuri; Tsumoto, Hiroki

    2015-01-01

    Soluble royal jelly protein is a candidate factor responsible for mammiferous cell proliferation. Major royal jelly protein 1 (MRJP1), which consists of oligomeric and monomeric forms, is an abundant proliferative protein in royal jelly. We previously reported that MRJP1 oligomer has biochemical heat resistance. Therefore, in the present study, we investigated the effects of several heat treatments (56, 65 and 96°C) on the proliferative activity of MRJP1 oligomer. Heat resistance studies showed that the oligomer molecular forms were slightly maintained until 56℃, but the molecular forms were converted to macromolecular heat-aggregated MRJP1 oligomer at 65℃ and 96℃. But, the growth activity of MRJP1 oligomer treated with 96°C was slightly attenuated when compared to unheated MRJP1 oligomer. On the other hand, the cell proliferation activity was preserved until 96℃ by the cell culture analysis of Jurkat cells. In contrast, those of IEC-6 cells were not preserved even at 56°C. The present observations suggest that the bioactive heat-resistance properties were different by the origin of the cells. The cell proliferation analysis showed that MRJP1 oligomer, but not MRJP2 and MRJP3, significantly increased cell numbers, suggesting that MRJP1 oligomer is the predominant proliferation factor for mammiferous cells. PMID:26020775

  10. Heat resistance of Listeria monocytogenes in vacuum packaged pasteurized fish fillets.

    PubMed

    Ben Embarek, P K; Huss, H H

    1993-11-01

    The heat resistance of two strains of Listeria monocytogenes in sous-vide cooked fillets of cod and salmon was investigated. Fish sticks of 5 g were inoculated, vacuum-packed and heated at different combinations of time and temperature (58-80 degrees C). Time-temperature combinations allowing survival and time-temperature combinations at which the bacteria were destroyed, were used to determine D- and z-values. D-values were in the range of what has been published for other food products. D60-values were between 1.95 and 4.48 min depending on the strain and the fish. Both strains were one-four-times more heat resistant in salmon than in cod, showing the importance of the heating menstruum. This difference may be due to the higher fat content in salmon as compared to cod. Z-values were calculated to be 5.65 and 6.4 degrees C, respectively, for the two strains. The suitability of methods for heat resistance experiments and the survival of L. monocytogenes in sous-vide cooked fish fillets are discussed. PMID:8268058

  11. Correction of the heat loss method for calculating clothing real evaporative resistance.

    PubMed

    Wang, Faming; Zhang, Chengjiao; Lu, Yehu

    2015-08-01

    In the so-called isothermal condition (i.e., Tair [air temperature]=Tmanikin [manikin temperature]=Tr [radiant temperature]), the actual energy used for moisture evaporation detected by most sweating manikins was underestimated due to the uncontrolled fabric 'skin' temperature Tsk,f (i.e., Tsk,fresistance. In this study, correction of the real evaporative heat loss from the wet fabric 'skin'-clothing system was proposed and experimentally validated on a 'Newton' sweating manikin. The real evaporative resistance of five clothing ensembles and the nude fabric 'skin' calculated by the corrected heat loss method was also reported and compared with that by the mass loss method. Results revealed that, depending on the types of tested clothing, different amounts of heat were drawn from the ambient environment. In general, a greater amount of heat was drawn from the ambient environment by the wet fabric 'skin'-clothing system in lower thermal insulation clothing than that in higher insulation clothing. There were no significant differences between clothing real evaporative resistances calculated by the corrected heat loss method and those by the mass loss method. It was therefore concluded that the correction method proposed in this study has been successfully validated. PMID:26267497

  12. Influence of interface mobility on the evolution of Austenite-Martensite grain assemblies during annealing

    SciTech Connect

    Clarke, Amy J; Santofimia, Maria J; Speer, John G; Zhao, L; Sietsma, Jilt

    2009-01-01

    The quenching and partitioning (Q&P) process is a new heat treatment for the creation of advanced high-strength steels. This treatment consists of an initial partial or full austenitization, followed by a quench to form a controlled amount of martensite and an annealing step to partition carbon atoms from the martensite to the austenite. In this work, the microstructural evolution during annealing of martensite-austenite grain assemblies has been analyzed by means of a modeling approach that considers the influence of martensite-austenite interface migration on the kinetics of carbon partitioning. Carbide precipitation is precluded in the model, and three different assumptions about interface mobility are considered, ranging from a completely immobile interface to the relatively high mobility of an incoherent ferrite-austenite interface. Simulations indicate that different interface mobilities lead to profound differences in the evolution of microstructure that is predicted during annealing.

  13. Toward high performance thermoset/carbon nanotube sheet nanocomposites via resistive heating assisted infiltration and cure.

    PubMed

    Kim, Jae-Woo; Sauti, Godfrey; Siochi, Emilie J; Smith, Joseph G; Wincheski, Russell A; Cano, Roberto J; Connell, John W; Wise, Kristopher E

    2014-11-12

    Thermoset/carbon nanotube (CNT) sheet nanocomposites were successfully fabricated by resistive heating assisted infiltration and cure (RHAIC) of the polymer matrix resin. Resistive heating takes advantage of the electrical and thermal conductivity of CNTs to rapidly and uniformly introduce heat into the CNT sheet. Heating the CNT sheet reduces the viscosity of the polymer resin due to localized temperature rise in close proximity to the resin, which enhances resin flow, penetration, and wetting of the CNT reinforcement. Once the resin infusion process is complete, the applied power is increased to raise the temperature of the CNT sheet, which rapidly cures the polymer matrix. Tensile tests were used to evaluate the mechanical properties of the processed thermoset/CNT sheet nanocomposites. The improved wetting and adhesion of the polymer resin to the CNT reinforcement yield significant improvement of thermoset/CNT nanocomposite mechanical properties. The highest specific tensile strength of bismaleimide(BMI)/CNT sheet nanocomposites was obtained to date was 684 MPa/(g/cm(3)), using 4 V (2 A) for resin infiltration, followed by precure at 10 V (6 A) for 10 min and post curing at 240 °C for 6 h in an oven. The highest specific Young's modulus of BMI/CNT sheet nanocomposite was 71 GPa/(g/cm(3)) using resistive heating infiltration at 8.3 V (4.7 A) for 3 min followed by resistive heating cure at 12.5 V (7 A) for 30 min. In both cases, the CNT sheets were stretched and held in tension to prevent relaxation of the aligned CNTs during the course of RHAIC. PMID:25325388

  14. Heat treating of a lamellar eutectic alloy (gamma/gamma prime + delta). [heat resistant alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Dreshfield, R. L.

    1976-01-01

    Eutectic superalloys are being developed at several laboratories for application as aircraft gas turbine airfoils. One such alloy was subjected to several heat treatments to determine if its mechanical properties could be improved. It was found that by partially dissolving the alloy at 1210 C and then aging at 900 C the tensile strength can be increased about 12 percent at temperatures up to 900 C. At 1040 C no change in tensile strength was observed. Times to rupture were measured between 760 and 1040 C and were essentially the same or greater than for as-grown material. Tensile and rupture ductility of the alloy are reduced by heat treatment. Photographs of the microstructure are shown.

  15. Low, medium and high heat tolerant strains of Listeria monocytogenes and increased heat stress resistance after exposure to sublethal heat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes exhibits sophisticated adaptive mechanisms to counteract higher levels of lethal acid, heat, salt or oxidative stresses after pre-exposure to sublethal concentrations of homogenous stress. A group of 37 strains representing all 13 serotypes of Listeria monocytogenes with initi...

  16. Challenges to a blow/fill/seal process with airborne microorganisms having different resistances to dry heat.

    PubMed

    Poisson, Patrick; Sinclair, Colin S; Tallentire, Alan

    2006-01-01

    Controlled challenges with air dispersed microorganisms having widely different resistances to dry heat, carried out on 624 BFS machine processing growth medium, have shown that higher the heat resistance, the greater the extent of vial contamination. Differences in heat resistance affected also the extent of vial contamination when parison and vial formation were knowingly manipulated through changes made to each of three process variables, provision of ballooning air, mould vacuum delay, and parison extrusion rate. The findings demonstrate that, in this investigational system, exposure of challenge micoorganisms to heat inherent in the process has a controlling influence on vial contamination, an influence that could also control microbiological risk in production environments. PMID:17089701

  17. Structural and Resistivity Changes in YBa2Cu3Oy Ceramics by Heat-Treatment in Air

    NASA Astrophysics Data System (ADS)

    Leng, Song; Narita, Nobutaka; Higashida, Kenji; Mazaki, Hiromasa

    1987-08-01

    Effect of heat-tretment in YBa2Cu3Oy ceramics was investigated using the methods of electrical resistivity, TG, DTA and X-ray diffraction. In the heating process, a mass increase and a resistivity decrease are observed in the sample in the temperature range 630-780 K. Heat-treatment in air at temperatures above 780 K causes the marked increase of resistivity as well as the decrease of oxygen content. The YBa2Cu3Oy compound is decomposed gradually above 1200 K and completely at around 1290 K. The degradation and recovery of structural and transport properties by heat-treatment in air are also reported.

  18. Heat-resistance of Hamigera avellanea and Thermoascus crustaceus isolated from pasteurized acid products.

    PubMed

    Scaramuzza, Nicoletta; Berni, Elettra

    2014-01-01

    Products containing sugar or fruit derivatives are usually subjected to a pasteurization process that can anyway be ineffective to kill ascospores from heat-resistant molds. Although the most occurring and economically relevant heat-resistant species belong to Byssochlamys, Neosartorya, Talaromyces, and Eupenicillium genera, an increasing number of uncommon heat-resistant isolates have been recently detected as spoiling microorganisms in such products. Since Hamigera spp. and Thermoascus spp. were those more frequently isolated at SSICA, heat resistance of Hamigera avellanea and Thermoascus crustaceus strains from pasteurized acid products was studied in apple juice, in blueberry and grape juice and in a buffered glucose solution. Data obtained from thermal death curves and statistical elaboration of raw data showed that D values of H. avellanea may vary between 11.11 and 66.67 min at 87°C, between 4.67 and 13.51 at 90°C, and between 0.43 and 1.52 min at 95°C. Similarly, D values of T. crustaceus may vary between 18.52 and 90.91 min at 90°C, between 2.79 and 19.23 at 93°C, and between 1.11 and 2.53 min at 95°C. For both strains studied, the z-values calculated from the decimal reduction time curves did not prove to be significantly influenced by the heating medium, that being 4.35°C, 5.39°C or 5.27°C for H. avellanea and 4.42°C, 3.69°C or 3.37°C for T. crustaceus, respectively in apple juice, in blueberry and grape juice or in the buffered glucose solution. Considering the pasteurization treatments industrially applied to fruit-based foods, the variation of thermal parameters does not seem to be a possible way to avoid product spoilage by these two species and only good practices applied to reduce the original load of heat-resistant fungi can help producers to prevent losses in contaminated finished products, as usually happens for other heat resistant molds. PMID:24239977

  19. Biofilm colonization dynamics and its influence on the corrosion resistance of austenitic UNS S31603 stainless steel exposed to Gulf of Mexico seawater.

    PubMed

    Acuña, Narciso; Ortega-Morales, Benjamin Otto; Valadez-González, Alex

    2006-01-01

    Viable bacterial counts, chemical markers, phospholipid fatty acid analysis (PLFA), and Fourier-transformed infrared spectroscopy (FTIR), together with electrochemical methods, were used to study biofilm dynamics and its impact on the corrosion resistance of UNS S31603 stainless steels exposed to the Gulf of Mexico seawater. Biofilms progressively accumulated, peaking on day 20, but finally detached. The extracellular polysaccharide (EPS)/cellular biomass ratio remained low most of the time, but reached its highest level (4.2+/-1.9) also on day 20. Viable bacterial cells reached their highest abundance earlier (approximately 800 CFU/cm2), on day 15. Biofilms were seen covering the stainless steel surfaces heterogeneously and were composed mainly of gram-negative rods, presumably EPS-producing bacteria. Despite the different levels of biofilm biomass and attachment state, field-exposed steel coupons ennobled significantly and showed more active pitting potentials (approximately +500 mVSCE) than on the abiotic control (+650 mVSCE), where no significant ennoblement occurred. These results suggest that the heterogeneous distribution of biofilms, as opposed to the quantity of surface-associated biomass, promotes formation of differential aeration cells, and that this in turn contributes to the ennoblement of these steels. PMID:16453199

  20. Austenite Formation in a Cold-Rolled Semi-austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Celada Casero, Carola; San Martín, David

    2014-04-01

    The progress of the martensite ( α') to austenite ( γ) phase transformation has been thoroughly investigated at different temperatures during the continuous heating of a cold-rolled precipitation hardening metastable stainless steel at a heating rate of 0.1 K/s. Heat-treated samples have been characterized using different experimental complementary techniques: high-resolution dilatometry, magnetization, and thermoelectric power (TEP) measurements, micro-hardness-Vickers testing, optical/scanning electron microscopy, and tensile testing. The two-step transformation behavior observed is thought to be related to the presence of a pronounced chemical banding in the initial microstructure. This banding has been characterized using electron probe microanalysis. Unexpectedly, dilatometry measurements seem unable to locate the end of the transformation accurately, as this technique does not detect the second step of this transformation (last 20 pct of it). It is shown that once the starting ( A S) and finishing ( A F) transformation temperatures have been estimated by magnetization measurements, the evolution of the volume fractions of austenite and martensite can be evaluated by TEP or micro-hardness measurement quite reliably as compared to magnetization measurements. The mechanical response of the material after being heated to temperatures close to A S, A F, and ( A F - A S)/2 is also discussed.

  1. Optimum PEC Conditions Under Resist Heating Effect Reduction for 90nm Node Mask Writing

    NASA Astrophysics Data System (ADS)

    Park, Eu Sang; Lee, Jong Hwa; Park, Dong Il; Jeong, Woo Gun; Seo, Soon Kyu; Kim, Jin Min; Choi, Sang-Soo; Jeong, Soo-Hong

    2002-12-01

    For high-voltage vector e-beam writing systems, solving the resist heating effect problem is one of the highest priorities because it is a major factor affecting localized critical dimension (CD) uniformity. In order to write patterns for 90nm node devices, the utilization of proximity effect correction (PEC) is essential for e-beam mask writers to achieve high CD performance. In this study, the dependence of CD variation on e-beam write conditions was investigated under optimum PEC parameter conditions. Writing conditions such as current density, shot size, number of writing passes, and settling time were tested to see their affects on resist heating. Industry-standard Nippon Zeon ZEP 7000 resist was written by a Toshiba EBM-3500B 50KeV vector e-beam writer using patterns found in sub-130nm node devices. Results indicated that the main factor affecting resist heating CD variation for ZEP 7000 was in fact the e-beam writer shot size selected. Multi-pass writing was effective in reducing the CD variation, and the settling time of each shot in the EBM-3500B had very little influence.

  2. Surface Resistance of Jute Fibre/Polylactic Acid Biocomposite to Wet Heat

    NASA Astrophysics Data System (ADS)

    Zandvliet, Clio; Bandyopadhyay, N. R.; Ray, Dipa

    2016-04-01

    Jute fibre/polylactic acid (PLA) composite is of special interest because both resin and reinforcement come from renewable resources. Thus, it could be a more eco-friendly alternative to glass fibre composite [1] and to conventional wood-based panels made with phenol-formaldehyde resin which present many drawbacks for the workers and the environment [2]. Yet the water affinity of the natural fibres, the susceptibility of PLA towards hydrolysis and the low glass transition of the PLA raise a question about the surface resistance of such composites to wet heat in service condition for a furniture application [3]. In this work, the surface resistance of PLA/jute composite alone and with two different varnishes are investigated in regard to an interior application following the standard test method in accordance to BS EN 18721:2009: "Furniture: assessment of surface resistance to wet heat". It is compared to two common wood based panels, plywood and hardboard. After test, the composite material surface is found to be more affected than plywood and hardboard, but it becomes resistant to wet heat when a layer of biosourced varnish or petrol-based polyurethane varnish are applied on the surface.

  3. The effect of pH on the heat production and membrane resistance of Streptococcus bovis.

    PubMed

    Russell, J B

    1992-01-01

    Non-growing cultures of Streptococcus bovis JB1 which were incubated in 2-[N-moropholino] ethane-sulfonic acid (MES)-phosphate buffer (pH 6.8) and glucose (2 g/l) produced heat at a rate of 0.17 mW/mg protein, and this rate was proportional to the enthalpy change of the homolactic fermentation. Since the growth-independent heat production could be eliminated by dicyclohexylcarbodiimide (DCCD), an inhibitor of F1F0 ATPases, it appeared that virtually all of the energy was being used to counteract proton flux through the cell membrane. When the pH was decreased from 6.8 to 5.8, heat production and glucose consumption increased, the electrical potential (delta psi) declined, the chemical gradient of protons (Z delta pH) increased, and there was a small increase in total protonmotive force (delta p). Further decreases in pH (5.8 to 4.5) caused a marked decrease in heat production and glucose consumption even though there was only a small decline in membrane voltage. Based on the enthalpy of ATP (4 kcal or 16.8 kJ/mol), it appeared that 38% of the wattage was passing through the cell membrane. The relationship between membrane voltage and membrane wattage or glucose consumption was non-linear (non-ohmic), and it appeared that the resistance of the membrane to current flow was not constant. Based on the electrical formula, resistance = voltage2/wattage and resistance = voltage/amperage, there was a marked increase in membrane resistance when the pH was less than 6.0. The increase in membrane resistance at low pH allowed S. bovis to maintain its membrane potential and expend less energy when its ability to ferment glucose was impaired. PMID:1444715

  4. Resistive wall heating due to image current on the beam chamber for a superconducting undulator.

    SciTech Connect

    Kim, S. H. )

    2012-03-27

    The image-current heating on the resistive beam chamber of a superconducting undulator (SCU) was calculated based on the normal and anomalous skin effects. Using the bulk resistivity of copper for the beam chamber, the heat loads were calculated for the residual resistivity ratios (RRRs) of unity at room temperature to 100 K at a cryogenic temperature as the reference. Then, using the resistivity of the specific aluminum alloy 6053-T5, which will be used for the SCU beam chamber, the heat loads were calculated. An electron beam stored in a storage ring induces an image current on the inner conducting wall, mainly within a skin depth, of the beam chamber. The image current, with opposite charge to the electron beam, travels along the chamber wall in the same direction as the electron beam. The average current in the storage ring consists of a number of bunches. When the pattern of the bunched beam is repeated according to the rf frequency, the beam current may be expressed in terms of a Fourier series. The time structure of the image current is assumed to be the same as that of the beam current. For a given resistivity of the chamber inner wall, the application ofthe normal or anomalous skin effect will depend on the harmonic numbers of the Fourier series of the beam current and the temperature of the chamber. For a round beam chamber with a ratius r, much larger than the beam size, one can assume that the image current density as well as the density square, may be uniform around the perimeter 2{pi}r. For the SCU beam chamber, which has a relatively narrow vertical gap compared to the width, the effective perimeter was estimated since the heat load should be proportional to the inverse of the perimeter.

  5. Estimating land surface heat flux using radiometric surface temperature without the need for an extra resistance

    NASA Astrophysics Data System (ADS)

    Su, H.; Yang, Y.; Liu, S.

    2015-12-01

    Remotely-sensed land surface temperature (LST) is a key variable in energy balance and is widely used for estimating regional heat flux. However, the inequality between LST and aerodynamic surface temperature (Taero) poses a great challenge for regional heat flux estimation in one -source energy balance models. In this study, a one-source model for land (OSML) was proposed to estimate regional surface heat flux without a need for an empirical extra resistance. The proposed OSML employs both a conceptual VFC/LST trapezoid model and the electrical analogue formula of sensible heat flux (H) to estimate the radiometric-convective resistance (rae) by using a quartic equation. To evaluate the performance of OSML, the model was applied to the Soil Moisture-Atmosphere Coupling Experiment (SMACEX), using a remotely-sensed data set at a regional scale. Validated against tower observations, the root mean square deviation (RMSD) of H and latent heat flux (LE) from OSML was 47 W/m2 and 51 W/m2, which is comparable to other published studies. OSML and SEBS (Surface Energy Balance System) compared under the same available energy indicated that LE estimated by OSML is comparable to that derived from the SEBS model. In conducting further inter-comparisons of rae, the aerodynamic resistance derived from SEBS (ra_SEBS), and aerodynamic resistance (ra) derived from Brutsaert et al. (2005) in corn and soybean fields, we found that rae and ra_SEBS are comparable. Most importantly, our study indicates that the OSML method is applicable without having to acquire wind speed or to specify aerodynamic surface characteristics and that it is applicable to heterogeneous areas.

  6. Genetic variation in resistance of the preimplantation bovine embryo to heat shock.

    PubMed

    Hansen, Peter J

    2014-12-01

    Reproduction is among the physiological functions in mammals most susceptible to disruption by hyperthermia. Many of the effects of heat stress on function of the oocyte and embryo involve direct effects of elevated temperature (i.e. heat shock) on cellular function. Mammals limit the effects of heat shock by tightly regulating body temperature. This ability is genetically controlled: lines of domestic animals have been developed with superior ability to regulate body temperature during heat stress. Through experimentation in cattle, it is also evident that there is genetic variation in the resistance of cells to the deleterious effects of elevated temperature. Several breeds that were developed in hot climates, including Bos indicus (Brahman, Gir, Nelore and Sahiwal) and Bos taurus (Romosinuano and Senepol) are more resistant to the effects of elevated temperature on cellular function than breeds that evolved in cooler climates (Angus, Holstein and Jersey). Genetic differences are expressed in the preimplantation embryo by Day 4-5 of development (after embryonic genome activation). It is not clear whether genetic differences are expressed in cells in which transcription is repressed (oocytes >100 µm in diameter or embryos at stages before embryonic genome activation). The molecular basis for cellular thermotolerance has also not been established, although there is some suggestion for involvement of heat shock protein 90 and the insulin-like growth factor 1 system. Given the availability of genomic tools for genetic selection, identification of genes controlling cellular resistance to elevated temperature could be followed by progress in selection for those genes within the populations in which they exist. It could also be possible to introduce genes from thermotolerant breeds into thermally sensitive breeds. The ability to edit the genome makes it possible to design new genes that confer protection of cells from stresses like heat shock. PMID:25472041

  7. Thermal resistance of naturally occurring airborne bacterial spores. [Viking spacecraft dry heat decontamination simulation

    NASA Technical Reports Server (NTRS)

    Puleo, J. R.; Bergstrom, S. L.; Peeler, J. T.; Oxborrow, G. S.

    1978-01-01

    Simulation of a heat process used in the terminal dry-heat decontamination of the Viking spacecraft is reported. Naturally occurring airborne bacterial spores were collected on Teflon ribbons in selected spacecraft assembly areas and subsequently subjected to dry heat. Thermal inactivation experiments were conducted at 105, 111.7, 120, 125, 130, and 135 C with a moisture level of 1.2 mg of water per liter. Heat survivors were recovered at temperatures of 135 C when a 30-h heating cycle was employed. Survivors were recovered from all cycles studied and randomly selected for identification. The naturally occurring spore population was reduced an average of 2.2 to 4.4 log cycles from 105 to 135 C. Heating cycles of 5 and 15 h at temperature were compared with the standard 30-h cycle at 111.7, 120, and 125 C. No significant differences in inactivation (alpha = 0.05) were observed between 111.7 and 120 C. The 30-h cycle differs from the 5- and 15-h cycles at 125 C. Thus, the heating cycle can be reduced if a small fraction (about 0.001 to 0.0001) of very resistant spores can be tolerated.

  8. Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

    DOEpatents

    Meek, T.T.; Blake, R.D.

    1985-04-03

    A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

  9. Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

    DOEpatents

    Meek, T.T.; Blake, R.D.

    1987-09-22

    A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate. 2 figs.

  10. Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

    DOEpatents

    Meek, Thomas T.; Blake, Rodger D.

    1987-01-01

    A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

  11. Structural and mechanical properties of heat-resistant granular nickel alloys

    SciTech Connect

    Eremenko, V.I.; Anoshkin, N.F.; Fatkullin, O.Kh.

    1992-05-01

    In order to realize the advantage afforded by granular metallurgy, it is necessary to know the laws of structure formation at every stage of the fabrication of semifinished products for heat-resistant nickel alloys. In this regard the structural features connected with the manufacture of granules by rapid cooling of a melt should be taken into account, as well as those related to the specific technological processes used in reworking (hot isostatic pressing - HIP) and heat treatment. 3 refs., 7 figs., 2 tabs.

  12. Heat dissipation due to ferromagnetic resonance in a ferromagnetic metal monitored by electrical resistance measurement

    SciTech Connect

    Yamanoi, Kazuto; Yokotani, Yuki; Kimura, Takashi

    2015-11-02

    The heat dissipation due to the resonant precessional motion of the magnetization in a ferromagnetic metal has been investigated. We demonstrated that the temperature during the ferromagnetic resonance can be simply detected by the electrical resistance measurement of the Cu strip line in contact with the ferromagnetic metal. The temperature change of the Cu strip due to the ferromagnetic resonance was found to exceed 10 K, which significantly affects the spin-current transport. The influence of the thermal conductivity of the substrate on the heating was also investigated.

  13. Role of Boundary Strengthening on Prevention of Type IV Failure in High Cr Ferritic Heat-Resistant Steels

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Tsukamoto, Susumu; Sawada, Kota; Abe, Fujio

    2013-10-01

    Microstructure evolution of newly developed 9Cr-3W-3Co-V, Nb steel with boron addition (B steel) has been analyzed during HAZ thermal cycle at the peak temperature of around Ac3 (Ac3 HAZ) and post-weld heat treatment (PWHT) to elucidate the prevention mechanism of type IV failure by boron addition. It was found that enhancement of the boundary strengthening by precipitates is the main reason for prevention of type IV failure by boron addition. In B steel HAZ, original austenite is reconstituted through martensitic α to γ reverse transformation during the heating and original martensite is reconstituted through martensitic transformation during cooling of the Ac3 HAZ thermal cycle. This process allows M23C6 carbides to precipitate at the prior austenite grain (PAG) and block boundaries during PWHT even if the chemical segregation of carbide forming elements exists. The effect of boundary strengthening on the creep property has also been investigated. Microstructure evolution during creep was compared among Gr.92 with different Ac3 HAZ microstructures prepared by three kinds of heat treatments and B steel. The results revealed that both the boundary length and kernel average misorientation value decreased in all samples during creep. However, this process occurred very rapidly in Ac3 HAZ simulated Gr.92, whereas it was significantly retarded in the other samples with sufficient boundary strengthening by precipitates. This result confirms that the precipitates formed at PAG and block boundaries play the most important role to stabilize the microstructure of Ac3 HAZ simulated samples during creep and prolong the creep life.

  14. Screening foods for processing-resistant bacterial spores and characterization of a pressure- and heat-resistant Bacillus licheniformis isolate.

    PubMed

    Ahn, Juhee; Balasubramaniam, V M

    2014-06-01

    This study was carried out to isolate pressure- and heat-resistant indicator spores from selected food matrices (black pepper, red pepper, garlic, and potato peel). Food samples were processed under various thermal (90 to 105°C) and pressure (700 MPa) combination conditions, and surviving microorganisms were isolated. An isolate from red pepper powder, Bacillus licheniformis, was highly resistant to pressure-thermal treatments. Spores of the isolate in deionized water were subjected to the combination treatments of pressure (0.1 to 700 MPa) and heat (90 to 121°C). Compared with the thermal treatment, the combined pressure-thermal treatments considerably reduced the numbers of B. licheniformis spores to less than 1.0 log CFU/g at 700 MPa plus 105°C and at 300 to 700 MPa plus 121°C. The inactivation kinetic parameters of the isolated B. licheniformis spores were estimated using linear and nonlinear models. Within the range of the experimental conditions tested, the pressure sensitivity (zP) of the spores decreased with increasing temperature (up to 121°C), and the temperature sensitivity (zT) was maximum at atmospheric pressure (0.1 MPa). These results will be useful for developing a combined pressure-thermal inactivation kinetics database for various bacterial spores. PMID:24853517

  15. The effects of neutron irradiation on fracture toughness of austenitic stainless steels.

    SciTech Connect

    Chopra, O. K.; Gruber, E. E.; Shack, W. J.

    1999-05-21

    Austenitic stainless steels are used extensively as structural alloys in reactor pressure vessel internal components because of their superior fracture toughness properties. However, exposure to high levels of neutron irradiation for extended periods leads to significant reduction in the fracture resistance of these steels. This paper presents results of fracture toughness J-R curve tests on four heats of Type 304 stainless steel that were irradiated to fluence levels of {approx}0.3 and 0.9 x 10{sup 21} n cm{sup {minus}2} (E >1 MeV) at {approx}288 C in a helium environment in the Halden heavy water boiling reactor. The tests were performed on 1/4-T compact tension specimens in air at 288 C; crack extensions were determined by both DC potential and elastic unloading compliance techniques.

  16. Influence of carbon partitioning kinetics on final Austenite fraction during quenching and partitioning

    SciTech Connect

    Clarke, Amy J; Speer, John G; Matlock, David K; Rizzo, F C; Edmonds, David V; Santofimia, Maria J

    2009-01-01

    The quenching and partitioning (Q&P) process is a two-stage heat-treatment procedure proposed for producing steel microstructures that contain carbon-enriched retained austenite. In Q&P processing, austenite stabilization is accomplished by carbon partitioning from supersaturated martensite. A quench temperature selection methodology was developed to predict an optimum process quench temperature; extension of this methodology to include carbon partitioning kinetics is developed here. Final austenite fraction is less sensitive to quench temperature than previously predicted, in agreement with experimental results.

  17. Effects of Animal Alimentary Passage on the Heat Resistance of Clostridium perfringens1

    PubMed Central

    Canada, James C.; Strong, Dorothy H.

    1965-01-01

    The resistance to heat, as measured by D values and phantom thermal death time curves, was observed to increase for one of three strains of Clostridium perfringens type A subsequent to animal passage. Animal passage was accomplished by the force-feeding of germ-free mice with bacterial suspensions of the organism, followed by the force-feeding of additional gnotobiotic mice with the contaminated feces. For the one strain in which an increase in heat resistance was noted, the result could not be attributed to mouse feces per se, since the presence of sterile germ-free mouse feces in a suspending medium did not protect C. perfringens spores from elevated temperature destruction. PMID:4286397

  18. Research on temperature control with numerical regulators in electric resistance furnaces with indirect heating

    NASA Astrophysics Data System (ADS)

    Diniş, C. M.; Popa, G. N.; Iagăr, A.

    2016-02-01

    The paper is an analysis of two-positions (hysteresis) regulators, self-tuned PID controller and PID controller for temperature control used for indirect heat resistance furnaces. For PID controller was used three methods of tuning: Ziegler-Nichols step response model, Cohen-Coon tuning rules and Ziegler-Nichols tuning rules. In experiments it used an electric furnace with indirect heating with active power of resistance of 1 kW/230V AC and a numerical temperature regulator AT-503 type (ANLY). It got a much better temperature control when using the Cohen-Coon tuning rules method than those of Ziegler-Nichols step response method and Ziegler-Nichols tuning rules method.

  19. Enhanced microwave absorbing properties and heat resistance of carbonyl iron by electroless plating Co

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-11-01

    Co coated carbonyl iron particles (Co (CI)) are fabricated through electroless plating method, and the electromagnetic microwave absorbing properties are investigated in the frequencies during 8.2-12.4 GHz. The complex permittivity of CI particles after electroless plating Co is higher than that of raw CI particles due to improvment of the polarization process. Furthermore, according to the XRD and TG results, the Co layer can enhance the heat resistance of CI particles. The bandwidth below -10 dB can reach 3.9 GHz for the Co(CI) absorbent. The results indicate that the electroless plating Co not only enhances the absorbing properties but also improves the heat resistance of CI.

  20. Specific heat and electrical resistivity of niobium measured by subsecond calorimetric technique

    NASA Astrophysics Data System (ADS)

    Maglić, K. D.; Perović, N. Lj.; Vuković, G. S.; Zeković, Lj. P.

    1994-09-01

    This paper presents results of measurements of specific heat and electrical resistivity of niobium from ambient temperature to the experimental limit of the equipment which is close to 2500 K. The study used a contact thermometry variant of the millisecond resolution pulse calorimetry developed at the Institute of Nuclear Sciences VINČA. In the experiments exceeding 1000 K, thermocouple thermometry was supplemented with parallel pyrometric temperature measurements. This, together with application of tungsten; rhenium thermocouple thermometry, increased the temperature range of measurements to 2500 K. In the range where two thermometries overlap, data on the specimen emittance were also generated. Novelties in the method, the results on electrical resistivity. specific heat, hemispherical total emittance and normal spectral emittance of niobium, and accuracies attained in different property measurements are discussed.

  1. Effects of erodant particle shape and various heat treatments on erosion resistance of plain carbon steel

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D. H.

    1981-01-01

    Erosion tests were conducted on 1045 steel samples which had been subjected to different heat treatments. The weight of material removed upon erosion with glass beads and crushed glass was measured. The data show that there is no correlation between hardness and erosion resistance. The erosion rate was strongly dependent on the shape of erodant particles, being an order of magnitude higher for erosion with crushed glass than with glass beads. Heat treatment had a profound effect on the erosion resistance when the erodant particles were glass beads but little or no effect when the particles were crushed glass. It is thus concluded that different mechanisms of material removal are involved with these two erodants. This conclusion is supported by the surface morphology of annealed 1045 steel samples which had been eroded by these two types of erodant particles. SEM micrographs of the eroded surfaces show that for erosion with glass beads it is deformation induced fracture of surface layers.

  2. A siphon method of determining resistivities of thin heat-pipe wicks

    NASA Technical Reports Server (NTRS)

    Katzoff, S.

    1978-01-01

    A simple siphon method is described for determining the resistivities of thin heat pipe wicks as a function of the pressure difference between the liquid in the wick and the vapor above it. The method was applied to wicks of one layer and two layers of 100 mesh (40 per centimeter) stainless steel screens diffusion bonded to stainless steel substrates. Some possible improvements in the method are suggested.

  3. Heat sealable, flame and abrasion resistant coated fabric. [clothing and containers for space exploration

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1981-01-01

    Flame retardant, abrasion resistant elastomeric compositions are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Coated fabrics employing such elastomeric compositions as coating film are flexible, lightweight, and air impermeable and can be made using heat or dielectric sealing procedures.

  4. An uncooled microbolometer focal plane array using heating based resistance nonuniformity compensation

    NASA Astrophysics Data System (ADS)

    Tepegoz, Murat; Oguz, Alp; Toprak, Alperen; Senveli, S. Ufuk; Canga, Eren; Tanrikulu, M. Yusuf; Akin, Tayfun

    2012-06-01

    This paper presents the performance evaluation of a unique method called heating based resistance nonuniformity compensation (HB-RNUC). The HB-RNUC method utilizes a configurable bias heating duration for each pixel in order to minimize the readout integrated circuit (ROIC) output voltage distribution range. The outputs of each individual pixel in a resistive type microbolometer differ from each other by a certain amount due to the resistance non-uniformity throughout the focal plane array (FPA), which is an inevitable result of the microfabrication process. This output distribution consumes a considerable portion of the available voltage headroom of the ROIC unless compensated properly. The conventional compensation method is using on-chip DACs to apply specific bias voltages to each pixel such that the output distribution is confined around a certain point. However, on-chip DACs typically occupy large silicon area, increase the output noise, and consume high power. The HB-RNUC method proposes modifying the resistances of the pixels instead of the bias voltages, and this task can be accomplished by very simple circuit blocks. The simplicity of the required blocks allows utilizing a low power, low noise, and high resolution resistance nonuniformity compensation operation. A 9-bit HB-RNUC structure has been designed, fabricated, and tested on a 384x288 microbolometer FPA ROIC on which 35μm pixel size detectors are monolithically implemented, in order to evaluate its performance. The compensation operation reduces the standard deviation of the ROIC output distribution from 470 mV to 9 mV under the same readout gain and bias settings. The analog heating channels of the HB-RNUC block dissipate around 4.1 mW electrical power in this condition, and the increase in the output noise due to these blocks is lower than 10%.

  5. 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.

  6. Wear behavior of austenite containing plate steels

    NASA Astrophysics Data System (ADS)

    Hensley, Christina E.

    As a follow up to Wolfram's Master of Science thesis, samples from the prior work were further investigated. Samples from four steel alloys were selected for investigation, namely AR400F, 9260, Hadfield, and 301 Stainless steels. AR400F is martensitic while the Hadfield and 301 stainless steels are austenitic. The 9260 exhibited a variety of hardness levels and retained austenite contents, achieved by heat treatments, including quench and tempering (Q&T) and quench and partitioning (Q&P). Samples worn by three wear tests, namely Dry Sand/Rubber Wheel (DSRW), impeller tumbler impact abrasion, and Bond abrasion, were examined by optical profilometry. The wear behaviors observed in topography maps were compared to the same in scanning electron microscopy micrographs and both were used to characterize the wear surfaces. Optical profilometry showed that the scratching abrasion present on the wear surface transitioned to gouging abrasion as impact conditions increased (i.e. from DSRW to impeller to Bond abrasion). Optical profilometry roughness measurements were also compared to sample hardness as well as normalized volume loss (NVL) results for each of the three wear tests. The steels displayed a relationship between roughness measurements and observed wear rates for all three categories of wear testing. Nanoindentation was used to investigate local hardness changes adjacent to the wear surface. DSRW samples generally did not exhibit significant work hardening. The austenitic materials exhibited significant hardening under the high impact conditions of the Bond abrasion wear test. Hardening in the Q&P materials was less pronounced. The Q&T microstructures also demonstrated some hardening. Scratch testing was performed on samples at three different loads, as a more systematic approach to determining the scratching abrasion behavior. Wear rates and scratch hardness were calculated from scratch testing results. Certain similarities between wear behavior in scratch testing

  7. Bacterial spore heat resistance correlated with water content, wet density, and protoplast/sporoplast volume ratio.

    PubMed Central

    Beaman, T C; Greenamyre, J T; Corner, T R; Pankratz, H S; Gerhardt, P

    1982-01-01

    Five types of dormant Bacillus spores, between and within species, were selected representing a 600-fold range in moist-heat resistance determined as a D100 value. The wet and dry density and the solids and water content of the entire spore and isolated integument of each type were determined directly from gram masses of material, with correction for interstitial water. The ratio between the volume occupied by the protoplast (the structures bounded by the inner pericytoplasm membrane) and the volume occupied by the sporoplast (the structures bounded by the outer pericortex membrane) was calculated from measurements made on electron micrographs of medially thin-sectioned spores. Among the various spore types, an exponential increase in the heat resistance correlated directly with the wet density and inversely with the water content and with the protoplast/sporoplast volume ratio. Altogether with results supported a hypothesis that the extent of heat resistance is based in whole or in part on the extent of dehydration and diminution of the protoplast in the dormant spore, without implications about physiological mechanisms for attaining this state. Images PMID:6802802

  8. Heat-resistant thermosetting resins and maleimido prepolymers based on a novel tetrakisaminophenoxycyclotriphosphazene

    SciTech Connect

    Kumar, D.; Gupta, A.D.; Khullar, M.

    1993-12-31

    A novel monomer, 2,2,4,4-tetrakis(4`-aminophenoxy)-6,6-diphenylcyclotriphosphazene (IV), useful for producing a variety of heat- and fire-resistant polymers, has been synthesized in good yield. Its synthesis involve Friedel-Frafts reaction of hexachlorocyclotriphosphazene (I) with benzene followed by the reaction of 2,2,4,4-tetrachloro-6,6-diphenylcyclotriphosphazene (II) with potassium 4-nitrophenoxide. The reduction of the obtained 2,2,4,4-tetrakis(4`-nitrophenoxy)-6, 6-diphenylcyclotriphosphazene (III) with molecular hydrogen in presence of PtO{sub 2} gave the tetrakisamine (IV). Heat-resistant thermosetting resins (X) and (XI) were synthesized by the reaction of tetrakisamine (IV) with maleic anhydride followed by insitu cyclodehydration and polymerization of the prepolymers (VIII) and (IX) at 235{+-}5{degrees}C for 1.5 and 290{degrees}C for 0.5 h. The TGA analysis of the developed cyclotriphosphazene containing cyclomatrix resins showed their thermal-stability up to 350{degrees}C and char yield of 71% in nitrogen at 800{degrees}C and 65% in air at 700{degrees}C. The structure of the synthesized monomer and intermediates were characterized by FT-IR, {sup 1}H-NMR, {sup 31}P-NMR, mass spectroscopy, DSC and elemental analysis. These resins are potential candidates for the development of heat-resistant composites, laminates, and adhesives in space, aerospace, and electronic industry.

  9. Significant effect of Ca2+ on improving the heat resistance of lactic acid bacteria.

    PubMed

    Huang, Song; Chen, Xiao Dong

    2013-07-01

    The heat resistance of lactic acid bacteria (LAB) has been extensively investigated due to its highly practical significance. Reconstituted skim milk (RSM) has been found to be one of the most effective protectant wall materials for microencapsulating microorganisms during convective drying, such as spray drying. In addition to proteins and carbohydrate, RSM is rich in calcium. It is not clear which component is critical in the RSM protection mechanism. This study investigated the independent effect of calcium. Ca(2+) was added to lactose solution to examine its influence on the heat resistance of Lactobacillus rhamnosus ZY, Lactobacillus casei Zhang, Lactobacillus plantarum P8 and Streptococcus thermophilus ND03. The results showed that certain Ca(2+) concentrations enhanced the heat resistance of the LAB strains to different extents, that is produced higher survival and shorter regrowth lag times of the bacterial cells. In some cases, the improvements were dramatic. More scientifically insightful and more intensive instrumental study of the Ca(2+) behavior around and in the cells should be carried out in the near future. In the meantime, this work may lead to the development of more cost-effective wall materials with Ca(2+) added as a prime factor. PMID:23617813

  10. High temperature setup for measurements of Seebeck coefficient and electrical resistivity of thin films using inductive heating.

    PubMed

    Adnane, L; Williams, N; Silva, H; Gokirmak, A

    2015-10-01

    We have developed an automated setup for simultaneous measurement of Seebeck coefficient S(T) and electrical resistivity ρ(T) of thin film samples from room temperature to ∼650 °C. S and ρ are extracted from current-voltage (I-V) measurements obtained using a semiconductor parameter analyzer and temperature measurements obtained using commercial thermocouples. The slope and the x-axis intercept of the I-V characteristics represent the sample conductance G and the Seebeck voltage, respectively. The measured G(T) can be scaled to ρ(T) by the geometry factor obtained from the room temperature resistivity measurement of the film. The setup uses resistive or inductive heating to control the temperature and temperature gradient on the sample. Inductive heating is achieved with steel plates that surround the test area and a water cooled copper pipe coil underneath that generates an AC magnetic field. The measurements can be performed using resistive heating only or inductive heating only, or a combination of both depending on the desired heating ranges. Inductive heating provides a more uniform heating of the test area, does not require contacts to the sample holder, can be used up to the Curie temperature of the particular magnetic material, and the temperature gradients can be adjusted by the relative positions of the coil and sample. Example results obtained for low doped single-crystal silicon with inductive heating only and with resistive heating only are presented. PMID:26520996

  11. Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

    NASA Astrophysics Data System (ADS)

    Liu, Feifei; Lan, Fengchong; Chen, Jiqing

    2016-07-01

    Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a "segmented" thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed "segmented" model shows more precise than the "non-segmented" model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the "segmented" model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

  12. Dependence of heat resistance of Drosophila on ambient temperature and relationship of this property to mutation process

    SciTech Connect

    Tikhomirova, M.M.; Belyatskaya, O.Ya.

    1986-04-01

    It has been demonstrated that thermosensitvity of the gametes in Drosophila line T correlates with the heat resistance of the flies. This property of the gametes is determined during ontogenesis, depending on the temperature during development and not by genotypic preadaptation as such, i.e., affinity of the females to the heat resistance line T. The ability of females to acquire heat resistance during the adult phase (in the first three days after emergence), i.e., by acclimatization to a temperature different from the temperature during development does not change the response of the gametes to extreme temperature which had developed during ontogenesis under a particular temperature.

  13. Heat and mass transport resistances in vacuum membrane distillation per drop

    SciTech Connect

    Bandini, S.; Sarti, G.C.

    1999-07-01

    Vacuum membrane distillation (VMD) is a separation process based on the use of microporous hydrophobic membranes. The membrane is located between an aqueous phase and a permeate, which is kept under vacuum at pressure values below the equilibrium vapor pressure of the feed. The liquid stream vaporizes at one side of the membrane, and the vapors diffuse through the gas phase inside the membrane pores. The process rate and performance are affected highly by the transport phenomena both in the liquid phase and through the membrane. Heat- and mass-transfer resistance in the liquid phase, as well as mass-transfer resistance through the membrane, play an important role in determining the process performance. Based on VMD experimental data for several binary aqueous mixtures containing volatile organic compounds, a simple criterion to investigate the role of each transport resistance on the separation efficiency is discussed.

  14. Researches upon the cavitation erosion behaviour of austenite steels

    NASA Astrophysics Data System (ADS)

    Bordeasu, I.; Popoviciu, M. O.; Mitelea, I.; Salcianu, L. C.; Bordeasu, D.; Duma, S. T.; Iosif, A.

    2016-02-01

    Paper analyzes the cavitation erosion behavior of two stainless steels with 100% austenitic structure but differing by the chemical composition and the values of mechanical properties. The research is based on the MDE(t) and MDER(t) characteristic curves. We studied supplementary the aspect of the eroded areas by other to different means: observations with performing optical microscopes and roughness measurements. The tests were done in the T2 vibratory facility in the Cavitation Laboratory of the Timisoara Polytechnic University. The principal purpose of the study is the identification of the elements influencing significantly the cavitation erosion resistance. It was established the effect of the principal chemical components (determining the proportion of the structural components in conformity the Schaffler diagram) upon the cavitation erosion resistance. The results of the researches present the influence of the proportion of unstable austenite upon cavitation erosion resistance. The stainless steel with the great proportion of unstable austenite has the best behavior. The obtained conclusion are important for the metallurgists which realizes the stainless steels used for manufacturing the runners of hydraulic machineries (turbines and pumps) with increased resistance to cavitation attack.

  15. Resistance heating of Fe and W in diamond-anvil cells

    NASA Technical Reports Server (NTRS)

    Boehler, R.; Nicol, M.; Zha, C. S.; Johnson, M. L.

    1986-01-01

    A new method for internally heating a diamond-anvil cell is described. Fine wires of iron or tungsten are resistively heated in a gasketed cell, thus providing a uniformly distributed pressure that can be measured in situ by employing the ruby scale. Temperatures of several thousand degrees have been measured by fitting a black body radiation function to the spectrum of the hot wire taken with an optical multichannel analyzer. Temperatures as high as the melting temperature of tungsten have been achieved. The alpha-gamma and alpha-epsilon phase transitions of iron have been studied, and the results show excellent agreement with previous data obtained with piston-cylinder or externally-heated diamond cells.

  16. Control of wire heating with resistively guided fast electrons through an inverse conical taper

    SciTech Connect

    Robinson, A. P. L. Schmitz, H.; Green, J. S.; Booth, N.; Ridgers, C. P.; Pasley, J.

    2015-04-15

    The heating of a solid wire embedded in a solid substrate (of lower Z material) with relativistic electrons generated by ultra-intense laser irradiation is considered. Previously, it has been noted that the initial angular distribution of the fast electrons is a highly important factor in the efficacy of the heating [Robinson et al., Phys. Plasmas 20, 122701 (2013)]. We show that, using 3D numerical simulations, the addition of an inverse conical taper at the front of wire can considerably improve the heating of the wire due to the reduction of angular spread of the fast electrons which is caused by transport through the inverse conical taper [Robinson et al., “Guiding of laser-generated fast electrons by exploiting the resistivity-gradients around a conical guide element,” Plasma Phys. Controlled Fusion (to be published)].

  17. Grain refinement of a nickel and manganese free austenitic stainless steel produced by pressurized solution nitriding

    SciTech Connect

    Mohammadzadeh, Roghayeh Akbari, Alireza

    2014-07-01

    Prolonged exposure at high temperatures during solution nitriding induces grain coarsening which deteriorates the mechanical properties of high nitrogen austenitic stainless steels. In this study, grain refinement of nickel and manganese free Fe–22.75Cr–2.42Mo–1.17N high nitrogen austenitic stainless steel plates was investigated via a two-stage heat treatment procedure. Initially, the coarse-grained austenitic stainless steel samples were subjected to an isothermal heating at 700 °C to be decomposed into the ferrite + Cr{sub 2}N eutectoid structure and then re-austenitized at 1200 °C followed by water quenching. Microstructure and hardness of samples were characterized using X-ray diffraction, optical and scanning electron microscopy, and micro-hardness testing. The results showed that the as-solution-nitrided steel decomposes non-uniformly to the colonies of ferrite and Cr{sub 2}N nitrides with strip like morphology after isothermal heat treatment at 700 °C. Additionally, the complete dissolution of the Cr{sub 2}N precipitates located in the sample edges during re-austenitizing requires longer times than 1 h. In order to avoid this problem an intermediate nitrogen homogenizing heat treatment cycle at 1200 °C for 10 h was applied before grain refinement process. As a result, the initial austenite was uniformly decomposed during the first stage, and a fine grained austenitic structure with average grain size of about 20 μm was successfully obtained by re-austenitizing for 10 min. - Highlights: • Successful grain refinement of Fe–22.75Cr–2.42Mo–1.17N steel by heat treatment • Using the γ → α + Cr{sub 2}N reaction for grain refinement of a Ni and Mn free HNASS • Obtaining a single phase austenitic structure with average grain size of ∼ 20 μm • Incomplete dissolution of Cr{sub 2}N during re-austenitizing at 1200 °C for long times • Reducing re-austenitizing time by homogenizing treatment before grain refinement.

  18. Combined Effect of Co and W on Deformation Resistance of 12Cr Heat-Resistant Steel for USC Steam Turbines

    NASA Astrophysics Data System (ADS)

    Cui, Huiran; Sun, Feng; Chen, Ke; Wu, Jiansheng

    2011-12-01

    12Cr heat-resistant steels with different concentrations of Co and W, with Mo equivalent (Mo + 1/2W) fixed at 1.6 wt.%, were prepared by arc-melting and hot rolling processes. Mechanical properties were evaluated by tensile tests conducted at a low strain rate 2 × 10-5 s-1 at 575, 600, and 625 °C. Microstructure of the steels was investigated via optical microscopy (OM) and electron transmission microscopy (TEM). The results show that when the content of W is fixed, the steel with 3.1 wt.% Co and the steel with 3.8 wt.% Co are found to obtain the best deformation resistance values at 575, 600, and at 625 °C; when the Co content is fixed, the steel with 1.5 wt.% W shows better performance. The highest ultimate tensile strength (UTS) and yield stress (YS) were achieved for the steel when its W content is at 1.5 wt.% and Co content is at 3.1 wt.% or 3.8 wt.%. Deformation resistance is related to the initial dislocation density in the steels, which increases with increasing Co content and decreases with increasing W content. It is verified that the deformation mechanism of the tested steels during high-temperature tensile tests at a low strain rate is that of the recovery-controlled dislocation creep. Furthermore, the thermodynamic calculation result is in agreement with the experimental result, demonstrating that 0.85Mo-1.5W-3.8Co steel has the best deformation resistance at 625 °C. Therefore, 0.85Mo-1.5W-3.1Co steel is recommended as a potential candidate material for 600 °C class steam turbines, and 0.85Mo-1.5W-3.8Co steel is also a potential material for 625 °C class Ultra supercritical (USC) steam turbines.

  19. Beam heat load due to geometrical and resistive wall impedance in COLDDIAG

    NASA Astrophysics Data System (ADS)

    Casalbuoni, S.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Spataro, B.

    2012-11-01

    One of the still open issues for the development of superconductive insertion devices is the understanding of the heat intake from the electron beam. With the aim of measuring the beam heat load to a cold bore and the hope to gain a deeper understanding in the underlying mechanisms, a cold vacuum chamber for diagnostics (COLDDIAG) was built. It is equipped with the following instrumentation: retarding field analyzers to measure the electron flux, temperature sensors to measure the beam heat load, pressure gauges, and mass spectrometers to measure the gas content. Possible beam heat load sources are: synchrotron radiation, wakefield effects due to geometrical and resistive wall impedance and electron/ion bombardment. The flexibility of the engineering design will allow the installation of the cryostat in different synchrotron light sources. COLDDIAG was first installed in the Diamond Light Source (DLS) in 2011. Due to a mechanical failure of the thermal transition of the cold liner, the cryostat had to be removed after one week of operation. After having implemented design changes in the thermal liner transition, COLDDIAG has been reinstalled in the DLS at the end of August 2012. In order to understand the beam heat load mechanism it is important to compare the measured COLDDIAG parameters with theoretical expectations. In this paper we report on the analytical and numerical computation of the COLDDIAG beam heat load due to coupling impedances deriving from unavoidable step transitions, ports used for pumping and diagnostics, surface roughness, and resistive wall. The results might have an important impact on future technological solutions to be applied to cold bore devices.

  20. Comparative evaluations of the weldability of modified 800H and other advanced austenitic stainless steels

    SciTech Connect

    Lundin, C.D.; Qiao, C.Y.P.

    1993-07-01

    The weldability of modified 800H was evaluated in terms of HAZ hot cracking susceptibility and HAZ softening tendency. Four other types of austenitic alloys, modified 316, 310Ta, HR3C and NF709, were employed to carry out a comparative study. It was found that modified 800H exhibits good weldability in terms of operability as contrasted to NF709. However, a higher HAZ hot cracking susceptibility for the modified 800H tubing heats was revealed as compared to the commercial tubing heats of HR3C and NF709. The hot cracking test results for the small laboratory prepared modified 800H heats showed an equivalent or better HAZ hot cracking resistance as compared to HR3C and NF709. Thus, it is anticipated that modified 800H tubing can show a hot cracking resistance equivalent to NF709 and HR3C if the base metal grain size is properly controlled and an optimum thermal mechanical treatment has been performed. The preliminary assessment on HAZ softening behavior for modified 800H, modified 316, 310Ta, HR3C and NF709 alloys is discussed.

  1. A molecular dynamics study of tilt grain boundary resistance to slip and heat transfer in nanocrystalline silicon

    SciTech Connect

    Chen, Xiang; Chen, Youping; Xiong, Liming; Chernatynskiy, Aleksandr

    2014-12-28

    We present a molecular dynamics study of grain boundary (GB) resistance to dislocation-mediated slip transfer and phonon-mediated heat transfer in nanocrystalline silicon bicrystal. Three most stable 〈110〉 tilt GBs in silicon are investigated. Under mechanical loading, the nucleation and growth of hexagonal-shaped shuffle dislocation loops are reproduced. The resistances of different GBs to slip transfer are quantified through their constitutive responses. Results show that the Σ3 coherent twin boundary (CTB) in silicon exhibits significantly higher resistance to dislocation motion than the Σ9 GB in glide symmetry and the Σ19 GB in mirror symmetry. The distinct GB strengths are explained by the atomistic details of the dislocation-GB interaction. Under thermal loading, based on a thermostat-induced heat pulse model, the resistances of the GBs to transient heat conduction in ballistic-diffusive regime are characterized. In contrast to the trend found in the dislocation-GB interaction in bicrystal models with different GBs, the resistances of the same three GBs to heat transfer are strikingly different. The strongest dislocation barrier Σ3 CTB is almost transparent to heat conduction, while the dislocation-permeable Σ9 and Σ19 GBs exhibit larger resistance to heat transfer. In addition, simulation results suggest that the GB thermal resistance not only depends on the GB energy but also on the detailed atomic structure along the GBs.

  2. Influence of deformation on the structure and mechanical and corrosion properties of high-nitrogen austenitic 07Kh16AG13M3 steel

    NASA Astrophysics Data System (ADS)

    Berezovskaya, V. V.; Khadyev, M. S.; Merkushkin, E. A.; Sokolovskaya, Yu. A.

    2013-11-01

    The correlation has been studied between the structure of a high-nitrogen austenitic Cr-Mn-N steel formed in the process of combined hardening treatment, including cold plastic deformation (CPD), and its mechanical and corrosion properties. The structure and properties of commercial high-nitrogen (0.8% N) 07Kh16AG13M3 steel is analyzed after rolling by CPD and aging at 500 and 800°C. It is shown that CPD of the steel occurs by dislocation slip and deformation twinning. Deformation twinning and also high resistance of austenite to martensitic transformations at true strains of 0.2 and 0.4 determine the high plasticity of the steel. The contribution of the structure imperfection parameters to the broadening of the austenite lines during CPD is estimated by X-ray diffraction. The main hardening factor is stated to be lattice microdistortions. Transmission electron microscopy study shows that heating of the deformed steel to 500°C leads to the formation of the intermediate CrN phase by a homogeneous mechanism, and the intermtallic χ phase forms along the austenite grain boundaries in the case of heating at 800°C. After hardening by all investigated technological schemes, exception for aging at 800°C, the steel does not undergo pitting corrosion and is slightly prone to a stress corrosion cracking during static bending tests, while aging at 800°C causes pitting corrosion at a pitting formation potential E pf = -0.25 V.

  3. Response of NBS encoding resistance genes linked to both heat and fungal stress in Brassica oleracea.

    PubMed

    Kim, Young-Wook; Jung, Hee-Jeong; Park, Jong-In; Hur, Yoonkang; Nou, Ill-Sup

    2015-01-01

    Environmental stresses, including both abiotic and biotic stresses, cause considerable yield loss in crops and can significantly affect their development. Under field conditions, crops are exposed to a variety of concurrent stresses. Among abiotic and biotic stresses, heat and Fusarium oxysporum, are the most important factors affecting development and yield productivity of Brassica oleracea. Genes encoding the nucleotide-binding site (NBS) motif are known to be related to responses to abiotic and biotic stresses in many plants. Hence, this study was conducted to characterize the NBS encoding genes obtained from transcriptome profiles of two cabbage genotypes with contrasting responses to heat stress, and to test expression levels of selected NBS- leucine reich repeat (LRR) genes in F. oxysporum infected plants. We selected 80 up-regulated genes from a total of 264 loci, among which 17 were confirmed to be complete and incomplete members of the TIR-NBS-LRR (TNL) class families, and another identified as an NFYA-HAP2 family member. Expression analysis using qRT-PCR revealed that eight genes showed significant responses to heat shock treatment and F. oxysporum infection. Additionally, in the commercial B. oleracea cultivars with resistance to F. oxysporum, the Bol007132, Bol016084, and Bol030522 genes showed dramatically higher expression in the F. oxysporum resistant line than in the intermediate and susceptible lines. The results of this study will facilitate the identification and the development of molecular markers based on multiple stress resistance genes related to heat and fungal stress under field conditions in B. oleracea. PMID:25461701

  4. Residual resistance of 2D and 3D structures and Joule heat release.

    PubMed

    Gurevich, V L; Kozub, V I

    2011-06-22

    We consider a residual resistance and Joule heat release in 2D nanostructures as well as in ordinary 3D conductors. We assume that elastic scattering of conduction electrons by lattice defects is predominant. Within a rather intricate situation in such systems we discuss in detail two cases. (1) The elastic scattering alone (i.e. without regard of inelastic mechanisms of scattering) leads to a transition of the mechanical energy (stored by the electrons under the action of an electric field) into heat in a traditional way. This process can be described by the Boltzmann equation where it is possible to do the configuration averaging over defect positions in the electron-impurity collision term. The corresponding conditions are usually met in metals. (2) The elastic scattering can be considered with the help of the standard electron-impurity collision integral only in combination with some additional averaging procedure (possibly including inelastic scattering or some mechanisms of electron wavefunction phase destruction). This situation is typical for degenerate semiconductors with a high concentration of dopants and conduction electrons. Quite often, heat release can be observed via transfer of heat to the lattice, i.e. via inelastic processes of electron-phonon collisions and can take place at distances much larger than the size of the device. However, a direct heating of the electron system can be registered too by, for instance, local measurements of the current noise or direct measurement of an electron distribution function. PMID:21628783

  5. Dissolved gas exsolution to enhance gas production and transport during bench-scale electrical resistance heating

    NASA Astrophysics Data System (ADS)

    Hegele, P. R.; Mumford, K. G.

    2015-05-01

    Condensation of volatile organic compounds in colder zones can be detrimental to the performance of an in situ thermal treatment application for the remediation of chlorinated solvent source zones. A novel method to increase gas production and limit convective heat loss in more permeable, potentially colder, zones involves the injection and liberation of dissolved gas from solution during heating. Bench-scale electrical resistance heating experiments were performed with a dissolved carbon dioxide and sodium chloride solution to investigate exsolved gas saturations and transport regimes at elevated, but sub-boiling, temperatures. At sub-boiling temperatures, maximum exsolved gas saturations of Sg = 0.12 were attained, and could be sustained when the carbon dioxide solution was injected during heating rather than emplaced prior to heating. This gas saturation was estimated to decrease groundwater relative permeability to krw = 0.64. Discontinuous gas transport was observed above saturations of Sg = 0.07, demonstrating the potential of exsolved CO2 to bridge vertical gas transport through colder zones.

  6. Intermetallic strengthened alumina-forming austenitic steels for energy applications

    NASA Astrophysics Data System (ADS)

    Hu, Bin

    In order to achieve energy conversion efficiencies of >50 % for steam turbines/boilers in power generation systems, materials required are strong, corrosion-resistant at high temperatures (>700°C), and economically viable. Austenitic steels strengthened with Laves phase and Ni3Al precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The creep resistance of these alloys is significantly improved through intermetallic strengthening (Laves-Fe 2Nb + L12-Ni3Al precipitates) without harmful effects on oxidation resistance. This research starts with microstructural and microchemical analyses of these intermetallic strengthened alumina-forming austenitic steels in a scanning electron microscope. The microchemistry of precipitates, as determined by energy-dispersive x-ray spectroscopy and transmission electron microscope, is also studied. Different thermo-mechanical treatments were carried out to these stainless steels in an attempt to further improve their mechanical properties. The microstructural and microchemical analyses were again performed after the thermo-mechanical processing. Synchrotron X-ray diffraction was used to measure the lattice parameters of these steels after different thermo-mechanical treatments. Tensile tests at both room and elevated temperatures were performed to study mechanical behaviors of this novel alloy system; the deformation mechanisms were studied by strain rate jump tests at elevated temperatures. Failure analysis and post-mortem TEM analysis were performed to study the creep failure mechanisms of these alumina-forming austenitic steels after creep tests. Experiments were carried out to study the effects of boron and carbon additions in the aged alumina-forming austenitic steels.

  7. Austenitic alloy and reactor components made thereof

    DOEpatents

    Bates, John F.; Brager, Howard R.; Korenko, Michael K.

    1986-01-01

    An austenitic stainless steel alloy is disclosed, having excellent fast neutron irradiation swelling resistance and good post irradiation ductility, making it especially useful for liquid metal fast breeder reactor applications. The alloy contains: about 0.04 to 0.09 wt. % carbon; about 1.5 to 2.5 wt. % manganese; about 0.5 to 1.6 wt. % silicon; about 0.030 to 0.08 wt. % phosphorus; about 13.3 to 16.5 wt. % chromium; about 13.7 to 16.0 wt. % nickel; about 1.0 to 3.0 wt. % molybdenum; and about 0.10 to 0.35 wt. % titanium.

  8. Viscous and resistive heating in the night side of the Hermean magnetosphere

    NASA Astrophysics Data System (ADS)

    Varela, Jacobo; Pantellini, Filippo; Moncuquet, Michel

    2015-04-01

    We show MHD simulations of the solar wind interaction with the magnetosphere of Mercury. We use the open source code AMRVAC in spherical geometry to study the regions of viscous and resistive heating in the Hermean magnetosphere depending on the orientation of the interplanetary magnetic field for a multipolar expansion of the Hermean magnetic field (Anderson, B. J. et al, 2012). We made two simulations with the same solar wind configuration but different magnetic field orientations (southward and northward cases). In the simulation with the southward orientation the plasma is heated nearby the magnetic X point in the magnetotail, where there is a transfer of magnetic energy (resistive dissipation) and by the damping of the flows (viscous dissipation) in internal and kinetic energy of the plasma, result of the balance between the Poynting and the non reversible energy fluxes with the enthalpy and kinetic energy fluxes. The hottest plasma is located in the equatorial plane close to the reconnection zone and is correlated with a region of large current and vorticity. If the solar wind is oriented in the northward direction there is no magnetic energy transfer to the plasma, the main heating mechanism is the viscous dissipation in the regions of shear flows nearby magnetopause. The hottest plasma is observed in the North of the magnetosphere where there is a local maximum of the vorticity. The plasma temperature in the Southward simulation is more than one order larger compared with the Northward case because there are two heating mechanism active at the same time. Both heating mechanisms are correlated and enhanced in the proximity of the magnetotail X point. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement SHOCK (project number 284515).

  9. Palm Cooling and Heating Delays Fatigue During Resistance Exercise in Women.

    PubMed

    Kwon, Young S; Robergs, Robert A; Mermier, Christine M; Schneider, Suzanne M; Gurney, Alfred B

    2015-08-01

    We previously reported that cold application to the palms between sets of high-intensity bench press exercise produces an ergogenic effect in men. In this study, we hypothesized that palm cooling (PC) or heating during rest intervals between high-intensity weight training sets will increase total repetitions and exercise volume load (kilograms) in resistance trained female subjects in a thermoneutral (TN) environment. Eight female subjects (mean ± SD, age = 25 ± 6 years, height = 160 ± 6 cm, body mass = 56 ± 7 kg, 1-repetition maximum [1RM] = 52 ± 6 kg, weight training experience = 6 ± 2 years) completed 4 sets of 85% 1RM bench press exercise to failure, with 3-minute rest intervals. Exercise trials were performed in a counterbalanced order on 3 days, separated by at least 3 days in TN, Palm heating (PH), and PC conditions. Heating and cooling were applied by placing both hands in a hand cooling device with the hand plate set to 45° C for heating and 10° C for cooling. Data were analyzed using a 2-factor repeated-measures analysis of variance and Tukey's post hoc tests. Palm cooling repetitions were significantly higher than TN repetitions during the second set, and PH repetitions were significantly higher than those of TN during the fourth set. Total exercise volume load (kilograms) for both PC (1,387 ± 358) and PH (1,349 ± 267) were significantly higher than TN (1,187 ± 262). In women, both heating and cooling of the palms between sets of resistance exercise increased the total exercise volume load performed. This ergogenic response to a peripheral sensory input is consistent with the central governor theory of muscular fatigue. PMID:23722108

  10. Procurement and screening test data for advanced austenitic alloys for 650/degree/C steam service: Part 2, final report

    SciTech Connect

    Swindeman, R.W.; Goodwin, G.M.; Maziasz, P.J.; Bolling, E.

    1988-08-01

    The results of screening tests on alloys from three compositional groups are summarized and compared to the alloy design and performance criteria identified as needed for austenitic alloys suitable as superheater/reheater tubing in advanced heat recovery systems. The three alloy groups included lean (nominally 14% Cr and 16% Ni) austenitic stainless steels that were modifications of type 316 stainless steel, 20Cr-30Ni-Fe alloys that were modifications of alloy 800H, and Ni-Cr aluminides, (Ni,Cr)/sub 3/Al. The screening tests covered fabricability, mechanical properties, weldability, and oxidation behavior. The lean stainless steels were found to possess excellent strength and ductility if cold-worked to an equivalent strain in the range 5 to 10% prior to testing. However, they possessed marginal weldability, poor oxidation resistance, and sensitivity to aging. The modified alloy 800H alloys also exhibited good strength and ductility in the cold-worked condition. The weldability was marginal, while the oxidation resistance was good. The aluminides were difficult to fabricate by methods typically used to produce superheater tubing alloys. The alloys that could be worked had marginal strength and ductility. An aluminide cast alloy, however, was found to be very strong and ductile. 23 refs., 19 figs., 13 tabs.

  11. Phase relations in the system Fe-Si determined in an internally-resistive heated DAC

    NASA Astrophysics Data System (ADS)

    Komabayashi, T.; Antonangeli, D.; Morard, G.; Sinmyo, R.; Mezouar, N.

    2015-12-01

    It is believed that the iron-rich Earth's core contains some amounts of light elements on the basis of the density deficit of 7 % compared to pure iron. The identification of the kinds and amounts of the light elements in the core places constraints on the origin, formation, and evolution of the Earth because dissolution of light elements into an iron-rich core should place important constraints on the thermodynamic conditions (pressure (P), temperature (T), and oxygen fugacity) of the equilibration between liquid silicate and liquid iron during the core formation. Among potential light elements, silicon has been attracting attentions because it is abundant in the mantle, partitioned into both solid and liquid irons, and very sensitive to the oxygen fugacity. An important phase relation in iron alloy is a transition between the face-centred cubic (FCC) structure and hexagonal close-packed (HCP) structure. This boundary is a key to infer the stable structure in the inner core and is used to derive thermodynamic properties of the phases (Komabayashi, 2014). In the Fe-Si system, previous reports were based on experiments in laser-heated diamond anvil cells (DAC), which might have included large termperature uncertainties. We have revisited this boundary in the system Fe-Si using an internally resistive-heated DAC combined with synchrotron X-ray diffraction at the beamline ID27, ESRF. The internally-heated DAC (Komabayashi et al., 2009; 2012) provides much more stable heating than the laser-heated DAC and much higher temperature than externally resistive-heated DAC, which enables us to place tight constraints on the P-T locations of the boundaries. Also because the minimum measurable temperature is as low as 1000 K due to the stable electric heating, the internal heating is able to examine the low temperature phase stability which was not studied by the previous studies. We will report the P-T locations of the boundaries and evaluate the effect of Si on the phase

  12. Influence of kinetics of supercooled austenite decomposition on structure formation in sparingly-alloyed tool steel

    NASA Astrophysics Data System (ADS)

    Krylova, S. E.; Yakovleva, I. L.; Tereshchenko, N. A.; Priimak, E. Yu.; Kletsova, O. A.

    2013-10-01

    The decomposition of supercooled austenite in 70Kh3G2VTB steel under isothermal conditions and continuous cooling have been studied. The isothermal and continuous cooling tranformation curves of the decomposition of austenite in the experimental steel have been constructed. The effect of alloying elements on phase transformations in the steel under heating and cooling have been established. The features of the formation of a microstructure in the 70Kh3G2VTB steel after different regimes of heat treatment have been described. The optimal parameters of hardening heat treatment have been developed.

  13. Ultrafine-Grained Structure of Fe-Ni-C Austenitic Alloy Formed by Phase Hardening

    NASA Astrophysics Data System (ADS)

    Danilchenko, Vitalij

    2016-02-01

    The X-ray and magnetometry methods were used to study α-γ transformation mechanisms on heating quenched Fe-22.7 wt.% Ni-0.58 wt.% C alloy. Variation of heating rate within 0.03-80 K/min allowed one to switch from diffusive to non-diffusive mechanism of the α-γ transformation. Heating up primary austenitic single crystal specimen at a rate of less than 1.0-0.5 K/min has led to formation of aggregate of grains with different orientation and chemical composition in the reverted austenite. Significant fraction of these grains was determined to have sizes within nanoscale range.

  14. Oxidation resistance of eight heat-resistant alloys at 870, 980, 1,095, and 1,150 C

    SciTech Connect

    Rundell, G.; McConnell, J. )

    1991-10-01

    Oxidation testing of heat-resistant alloys is described. The testing procedure utilized weight-gain measurements using one specimen, which was withdrawn and weighted at intervals of 1 week, for 10-18 weeks. The specimen was placed in a porcelain cup during exposure and covered upon cooling to retain spalled oxide. Weight gain was used to determine the kinetics of oxidation and was extrapolated to 3,000 hr. The specimen was withdrawn at the end of the exposure, weighed, cathodically descaled, and reweighed. The ratio of oxygen ions to metal ions was determined for each alloy and test temperature. This ratio approaches the stoichiometric ratio for Fe{sub 3}O{sub 4} or Cr{sub 2}O{sub 3}. The ratio for each test is used to convert weight gain to weight loss. The amount of adherent oxide was determined as well as the total amount of oxide, leading to an expression for oxide adherency. The oxidation resistance of Fe-Cr-Ni alloys increased with increasing Cr and Ni, with Cr being the most critical element. Additions of Si, Al, or Ce were shown to extend the usefulness of Fe-Cr-Ni alloys.

  15. Heat-Resistant Co-W Catalytic Metals for Multilayer Graphene Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Ueno, Kazuyoshi; Karasawa, Yusuke; Kuwahara, Satoru; Baba, Shotaro; Hanai, Hitoshi; Yamazaki, Yuichi; Sakuma, Naoshi; Kajita, Akihiro; Sakai, Tadashi

    2013-04-01

    Multilayer graphene (MLG) is expected to be a low-resistance and high-reliability interconnect material replacing copper (Cu) in nanoscale interconnects. Chemical vapor deposition (CVD) on catalytic metals is expected as a practical method for MLG deposition. To obtain high-quality MLG films without catalyst agglomeration by CVD, heat-resistant Co-W catalytic metals were investigated. The agglomeration of the Co-W catalytic metals was suppressed by increasing the W composition; however, MLG deposition was suppressed at the same time. The effects of W addition on the MLG growth were discussed from the viewpoints of the crystallographic change of the Co-W catalysts and chemical reactions. It was found that the Co grain size was reduced and the fcc Co formation was suppressed by W addition. In addition, graphite formation was supposed to be suppressed by W addition owing to the formation of phases other than fcc Co according to the Co-W-C phase diagram. With the optimum W concentration, MLG crystallinity was improved by high-temperature CVD using the heat-resistant Co-W catalytic metals (0.7 at. %) without agglomeration, compared with that in the case of using pure-Co catalysts.

  16. Development of Alumina-Forming Austenitic Stainless Steels

    SciTech Connect

    Brady, Michael P; Yamamoto, Yukinori; Bei, Hongbin; Santella, Michael L; Maziasz, Philip J

    2009-01-01

    This paper presents the results of the continued development of creep-resistant, alumina-forming austenitic (AFA) stainless steel alloys, which exhibit a unique combination of excellent oxidation resistance via protective alumina (Al2O3) scale formation and high-temperature creep strength through the formation of stable nano-scale MC carbides and intermetallic precipitates. Efforts in fiscal year 2009 focused on the characterization and understanding of long-term oxidation resistance and tensile properties as a function of alloy composition and microstructure. Computational thermodynamic calculations of the austenitic matrix phase composition and the volume fraction of MC, B2-NiAl, and Fe2(Mo,Nb) base Laves phase precipitates were used to interpret oxidation behavior. Of particular interest was the enrichment of Cr in the austenitic matrix phase by additions of Nb, which aided the establishment and maintenance of alumina. Higher levels of Nb additions also increased the volume fraction of B2-NiAl precipitates, which served as an Al reservoir during long-term oxidation. Ageing studies of AFA alloys were conducted at 750 C for times up to 2000 h. Ageing resulted in near doubling of yield strength at room temperature after only 50 h at 750 C, with little further increase in yield strength out to 2000 h of ageing. Elongation was reduced on ageing; however, levels of 15-25% were retained at room temperature after 2000 h of total ageing.

  17. Control of Byssochlamys and Related Heat-resistant Fungi in Grape Products

    PubMed Central

    King, A. Douglas; Michener, H. David; Ito, Keith A.

    1969-01-01

    Heat-resistant strains of Byssochlamys fulva, B. nivea, and other heat-resistant fungi were isolated from vineyard soil, grapes, grape-processing lines, and waste pomace. They are known to remain in grape juice occasionally and to grow in grape juice products. Ascospores of these fungi have a D value (decimal reduction time) of about 10 min at 190 F (88 C), but in the presence of 90 μliters of SO2 per liter (normally added to the juice) the D value was cut in half. Filtration through a commercial diatomaceous filter aid (also a common processing step) entrapped all but about 0.001% of experimentally added spores. Thus, heat in the presence of SO2 and filtration together can reduce the population of these spores by several orders of magnitude. Growth was also prevented by benzoate or sorbate in low concentrations. Oxygen must be reduced to extremely low levels before lack of oxygen limits growth. Images PMID:16349856

  18. Specific heat, electrical resistivity and thermoelectric power of YbNi{sub 4}Si

    SciTech Connect

    Kowalczyk, A.; Falkowski, M. Tolinski, T.; Tran, V.H.; Miiller, W.; Reiffers, M.; Timko, M.

    2008-01-08

    The studies of the specific heat, electrical resistivity and thermoelectric power of YbNi{sub 4}Si are reported. These studies are supported by magnetic susceptibility and X-ray photoemission spectroscopy (XPS) measurements. YbNi{sub 4}Si does not order magnetically down to 4 K. Nearly in the whole temperature range studied the magnetic susceptibility follows a Curie law with {mu}{sub eff} = 4.15 {mu}{sub B}/f.u. This effective magnetic moment is close to the value expected for the 4f{sup 13} configuration (4.54 {mu}{sub B}). The Yb{sup 2+} and Yb{sup 3+} peaks observed by XPS in the valence band region confirm the domination of the Yb{sup 3+} valence state. Based on the specific heat measurements, the electronic specific heat coefficient {gamma} = 25 mJ/mol/K{sup 2} and the Debye temperature {theta}{sub D} = 320 K were derived. A quadratic dependence of electrical resistivity at low temperatures has been observed. The Kadowaki-Woods ratio has been discussed. The thermoelectric power has been analyzed in the framework of the two band model.

  19. Survival and Heat Resistance of Listeria monocytogenes after Exposure to Alkali and Chlorine

    PubMed Central

    Taormina, P. J.; Beuchat, L. R.

    2001-01-01

    A strain of Listeria monocytogenes isolated from a drain in a food-processing plant was demonstrated, by determination of D values, to be more resistant to the lethal effect of heat at 56 or 59°C following incubation for 45 min in tryptose phosphate broth (TPB) at pH 12.0 than to that of incubation for the same time in TPB at pH 7.3. Cells survived for at least 6 days when they were suspended in TPB at pHs 9.0, 10.0, and 11.0 and stored at 4 or 21°C. Cells of L. monocytogenes incubated at 37°C for 45 min and then stored for 48 or 144 h in TPB at pH 10.0 were more resistant to heat treatment at 56°C than were cells stored in TPB at pH 7.3. The alkaline-stress response in L. monocytogenes may induce resistance to otherwise lethal thermal-processing conditions. Treatment of cells in 0.05 M potassium phosphate buffer (pH 7.00 ± 0.05) containing 2.0 or 2.4 mg of free chlorine per liter reduced populations by as much as 1.3 log10 CFU/ml, while treatment with 6.0 mg of free chlorine per liter reduced populations by as much as 4.02 log10 CFU/ml. Remaining subpopulations of chlorine-treated cells exhibited some injury, and cells treated with chlorine for 10 min were more sensitive to heating at 56°C than cells treated for 5 min. Contamination of foods by L. monocytogenes cells that have survived exposure to processing environments ineffectively cleaned or sanitized with alkaline detergents or disinfectants may have more severe implications than previously recognized. Alkaline-pH-induced cross-protection of L. monocytogenes against heat has the potential to enhance survival in minimally processed as well as in heat-and-serve foods and in foods on holding tables, in food service facilities, and in the home. Cells surviving exposure to chlorine, in contrast, are more sensitive to heat; thus, the effectiveness of thermal processing in achieving desired log10-unit reductions is not compromised in these cells. PMID:11375163

  20. The critical analysis of austenitic manganese steel T130Mn135 used for castings in the mining industry

    NASA Astrophysics Data System (ADS)

    Josan, A.; Pinca Bretotean, C.; Putan, V.

    2016-02-01

    This paper presents the critical analysis of making technology of austenitic manganese steel T130Mn135, used for castings of the type Mills hammer at a Romanian foundry. Are analyzed 11 charges of steel for castings and is determined the diagram of the heat treatment. After the applying of the heat treatment results a single-phase structure, consisting of homogeneous austenite. For all the 11 charges is presented the variation of chemical composition.

  1. Effect of residual austenite on the tendency of incompletely aged maraging steels to embrittlement during slow deformation

    SciTech Connect

    Kardonskii, V.M.; Gorbunova, N.B.

    1986-03-01

    The authors investigate the high-strength maraging steels (HSMS) N17K10V10MT and N18V10V10MT by cyclic heat treatment and heating to temperatures of the dual-phase (alpha + gamma)-region. Embrittlement during the slow loading of incompletely aged HSMS with titanium can be reduced when approximately 20% of residual austenite is obtained in them. Maraging steel containing residual austenite in the initial state does not tend toward this type of embrittlement.

  2. Improved Temperature-Gradient Incubator and the Maximal Growth Temperature and Heat Resistance of Salmonella

    PubMed Central

    Elliott, R. Paul; Heiniger, Patricia K.

    1965-01-01

    An improved all-metal temperature-gradient incubator produces its gradient by means of a bar permanently installed in a near-vertical position with its lower end in a cool constant-temperature water bath and with thermostatically controlled heaters near its top. Bolts hold the incubator in contact with the temperature-gradient bar, and polyurethane foam insulates the entire assemblage during use. Maximal growth temperatures of 34 representative strains of Salmonella were found to be between 43.2 and 46.2 C. In an agar medium with an initial level of 106 cells per milliliter, no strain survived 50 C for 48 hr. S. senftenberg 775W showed no greater heat resistance at or near 48 C than did other species or other S. senftenberg strains. However, it was considerably more resistant than other strains at 55 C. Images Fig. 2 PMID:14264850

  3. Direct observation of resistive heating at graphene wrinkles and grain boundaries

    SciTech Connect

    Grosse, Kyle L.; Dorgan, Vincent E.; Estrada, David; Wood, Joshua D.; Vlassiouk, Ivan V; Eres, Gyula; Lyding, Joseph W; King, William P.; Pop, Eric

    2014-01-01

    We directly measure the nanometer-scale temperature rise at wrinkles and grain boundaries (GBs) in functioning graphene devices by scanning Joule expansion microscopy with 50 nm spatial and 0.2K temperature resolution. We observe a small temperature increase at select wrinkles and a large (100 K) temperature increase at GBs between coalesced hexagonal grains. Comparisons of measurements with device simulations estimate the GB resistivity (8 150 X lm) among the lowest reported for graphene grown by chemical vapor deposition. An analytical model is developed, showing that GBs can experience highly localized resistive heating and temperature rise, most likely affecting the reliability of graphene devices. Our studies provide an unprecedented view of thermal effects surrounding nanoscale defects in nanomaterials such as graphene.

  4. Direct observation of resistive heating at graphene wrinkles and grain boundaries

    NASA Astrophysics Data System (ADS)

    Grosse, Kyle L.; Dorgan, Vincent E.; Estrada, David; Wood, Joshua D.; Vlassiouk, Ivan; Eres, Gyula; Lyding, Joseph W.; King, William P.; Pop, Eric

    2014-10-01

    We directly measure the nanometer-scale temperature rise at wrinkles and grain boundaries (GBs) in functioning graphene devices by scanning Joule expansion microscopy with ˜50 nm spatial and ˜0.2 K temperature resolution. We observe a small temperature increase at select wrinkles and a large (˜100 K) temperature increase at GBs between coalesced hexagonal grains. Comparisons of measurements with device simulations estimate the GB resistivity (8-150 Ω μm) among the lowest reported for graphene grown by chemical vapor deposition. An analytical model is developed, showing that GBs can experience highly localized resistive heating and temperature rise, most likely affecting the reliability of graphene devices. Our studies provide an unprecedented view of thermal effects surrounding nanoscale defects in nanomaterials such as graphene.

  5. Effect of Heat Treatment on Wear Resistance of Nickel Aluminide Coatings Deposited by HVOF and PTA

    NASA Astrophysics Data System (ADS)

    Benegra, M.; Santana, A. L. B.; Maranho, O.; Pintaude, G.

    2015-08-01

    This study aims to compare the wear resistance of nickel aluminide coatings deposited using plasma transferred arc (PTA) and high-velocity oxygen fuel (HVOF) processes. Wear resistance was measured in rubber wheel abrasion tests. In both deposition processes, the same raw material (nickel aluminide powder) was atomized and deposited on a 316L steel plate substrate. After deposition, specimens were subjected to thermal cycling, aiming solubilization and precipitation. Coatings deposited using PTA developed different microstructures as a result of the incorporation of substrate elements. However, despite the presence of these microstructures, they performed better than coatings processed using HVOF before the heat treatment. After thermal cycling, the superficial hardness after the wear tests for both processes was similar, resulting in similar mass losses.

  6. Multiplexed Optical Transmission System For Automobiles Using Polymer Fiber With High Heat Resistance

    NASA Astrophysics Data System (ADS)

    Sasayama, Takao; Asano, Hideki; Taketani, Noriaki

    1989-02-01

    A multiplexed optical transmission system for automobiles utilizing newly developed polymer fiber has been proposed. The system is composed with a star-shaped optical network, in which the ootical signals can be transmitted bi-directionally through polymer optical fiber and optical branches with the central and local controllers. The polymer fiber has been developed for this purpose in order to overcome the conventional problems which prevented its wide use for a long time. The new polymer fiber is fabricated with a thereto-setting resin for core which is pushed out from heating furnace after the process of polymerization. The fiber shows the desirable characteristics for this application, that is, the heat resistance is as high as 200°C, and the transmission loss is as low as 0.5003/m at 660 nm wavelength.

  7. Joule heating effect in nonpolar and bipolar resistive random access memory

    NASA Astrophysics Data System (ADS)

    Uenuma, Mutsunori; Ishikawa, Yasuaki; Uraoka, Yukiharu

    2015-08-01

    The position of the conductive filament (CF) and the heating behaviour during a switching process in nonpolar and bipolar resistive random access memories (ReRAMs) were evaluated using thermal analysis. The position of the CF was clearly observed from Joule heating at the surface of the electrode on the CF. The position of the CF did not change during the switching cycle, except in the case of an unstable CF. In the nonpolar ReRAM, spike-shaped temperature increments were observed during both the forming and the set processes because of the overshoot current. However, the behaviour of the temperature increment in the bipolar ReRAM was virtually consistent with the profile of the electrical power.

  8. High-Temperature Experiments using a Resistively-Heated High-Pressure Membrane Diamond Anvil Cell

    SciTech Connect

    Jenei, Z; Visbeck, K; Cynn, H; Yoo, C; Evans, W

    2009-04-22

    A reliable high-performance heating method using resistive heaters and a membrane driven diamond anvil cell (mDAC) is presented. Two micro-heaters are mounted in a mDAC and use electrical power of less than 150 W to achieve sample temperatures up to 1200 K. For temperature measurement we use two K-type thermocouples mounted near the sample. The approach can be used for in-situ Raman spectroscopy and x-ray diffraction at high pressures and temperatures. A W-Re alloy gasket material permits stable operation of mDAC at high temperature. Using this method, we made an isothermal compression at 900 K to pressures in excess of 100 GPa and isobaric heating at 95 GPa to temperatures in excess of 1000 K. As an example, we present high temperature Raman spectroscopy measurements of nitrogen at high pressures.

  9. HYDROGEN-ASSISTED FRACTURE IN FORGED TYPE 304L AUSTENITIC STAINLESS STEEL

    SciTech Connect

    Switzner, Nathan; Neidt, Ted; Hollenbeck, John; Knutson, J.; Everhart, Wes; Hanlin, R.; Bergen, R.; Balch, D. K.

    2012-09-06

    Austenitic stainless steels generally have good resistance to hydrogen-assisted fracture; however, structural designs for high-pressure gaseous hydrogen are constrained by the low strength of this class of material. Forging is used to increase the low strength of austenitic stainless steels, thus improving the efficiency of structural designs. Hydrogen-assisted racture, however, depends on microstructural details associated with manufacturing. In this study, hydrogen-assisted fracture of forged type 304L austenitic stainless steel is investigated. Microstructural variation in multi-step forged 304L was achieved by forging at different rates and temperatures, and by process annealing. High internal hydrogen content in forged type 304L austenitic stainless steel is achieved by thermal precharging in gaseous hydrogen and results in as much as 50% reduction of tensile ductility.

  10. Airflow resistance of heat and moisture exchange filters with and without a tracheostoma valve.

    PubMed

    Verkerke, Gijsbertus Jacob; Geertsema, Albert Anne; Schutte, Harm K

    2002-04-01

    Rehabilitation of laryngectomees has been furthered by the introduction of heat and moisture exchange (HME) filters, placed over a tracheostoma or on a tracheostoma valve (TSV). The airflow resistance of HME filters is an important factor with regard to the comfort of the patient. The goal of this study was to determine the airflow resistance (defined as the pressure drop over the device divided by the squared airflow through the device) of 4 commercially available HME filters with and without a TSV. The pressure drop over and the airflow through the devices were measured in vitro. Distinct differences among the devices were found. The mean airflow resistance of the HME filters ranged from 135 to 346 Pa x s2/L2, that of TSVs was between 66 and 297 Pa x s2/L2, and that of the combination was between 263 and 454 Pa x s2/L2. The Stom-Vent 2 HME filter and the Adeva Window TSV with an Adeva filter had the lowest airflow resistance of the devices measured in this study. PMID:11991585

  11. The Further Development of Heat-Resistant Materials for Aircraft Engines

    NASA Technical Reports Server (NTRS)

    Bollenrath, Franz

    1946-01-01

    The present report deals with the problems involved in the greater utilization and development of aircraft engine materials, and specifically; piston materials, cylinder heads, exhaust valves, and exhaust gas turbine blading. The blades of the exhaust gas turbine are likely to be the highest stressed components of modern power plants from a thermal-mechanical and chemical standpoint, even though the requirements on exhaust valves of engines with gasoline injection are in general no less stringent. For the fire plate in Diesel engines the specifications for mechanical strength and design are not so stringent, and the question of heat resistance, which under these circumstances is easier obtainable, predominates.

  12. Boron and Zirconium from Crucible Refractories in a Complex Heat-Resistant Alloy

    NASA Technical Reports Server (NTRS)

    Decker, R F; Rowe, John P; Freeman, J W

    1958-01-01

    In a laboratory study of the factors involved in the influence of induction vacuum melting on 55ni-20cr-15co-4mo-3ti-3al heat resistant alloy, it was found that the major factor was the type of ceramic used as the crucible. The study concluded that trace amounts of boron or zirconium derived from reaction of the melt with the crucible refactories improved creep-rupture properties at 1,600 degrees F. Boron was most effective and, in addition, markedly improved hot-workability.

  13. Production of Heat Resistant Composite based on Siloxane Elastomer and Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Bessonov, I. V.; Karelina, N. V.; Kopitsyna, M. N.; Morozov, A. S.; Reznik, S. V.; Skidchenko, V. Yu.

    2016-02-01

    Development of a new generation of composite with unique thermal properties is an important task in the fields of science and technology where material is operated at high temperatures and exposure to a short-wave radiation. Recent studies show that carbon nanomaterials (fullerenes and carbon nanotubes) could improve the thermal, radiation and thermal-oxidative stability of the polymer matrix. In this article the development of a new heat resistant composite based on elastomer and carbon nanotubes (CNT) was performed and physicochemical properties of final product were evaluated.

  14. Fire and heat resistant laminating resins based on maleimido substituted aromatic cyclotriphosphazene polymer

    NASA Technical Reports Server (NTRS)

    Kumar, Devendra (Inventor); Fohlen, George M. (Inventor); Parker, John A. (Inventor)

    1987-01-01

    4-Aminophenoxy cyclotriphosphazenes are reacted with maleic anhydride to produce maleamic acids which are converted to the maleimides. The maleimides are polymerized. By selection of starting materials (e.g., hexakis amino or trisaminophenoxy trisphenoxy cyclotriphosphazenes), selection of molar proportions of reactants, use of mixtures of anhydrides and use of dianhydrides as bridging groups a variety of maleimides and polymers are produced. The polymers have high limiting oxygen indices, high char yields and other useful heat and fire resistant properties making them useful as, for example, impregnants of fabrics.

  15. Development of heat resistant polyphenol compounds applied to the spin-on carbon hardmask

    NASA Astrophysics Data System (ADS)

    Makinoshima, Takashi; Satou, Takashi; Horiuchi, Junya; Okada, Kana; Shimizu, Yoko; Echigo, Masatoshi

    2016-03-01

    In this paper, we report the development of a new polyphenol, NF7177, applied to the Spin-On Carbon Hardmask and the thermosetting properties. The new polyphenol derivatives were easily synthesized by the condensation of aldehydes and dihydroxybiphenyl compounds. We found new polyphenol NF7177 was showed the good applicability to the raw material for the Spin-On Carbon Hardmask [1]. It was indicated that the heat resistance of NF7177 was due to cross-linking based on dehydration reaction. Furthermore the thermosetting properties seem to be depend on the number and position of OH group.

  16. Resistant starch improvement of rice starches under a combination of acid and heat-moisture treatments.

    PubMed

    Hung, Pham Van; Vien, Ngo Lam; Lan Phi, Nguyen Thi

    2016-01-15

    The effects of a combination of acid and heat-moisture treatment on formation of resistant starch (RS) and characteristics of high-amylose, normal and waxy rice starches were investigated in this study. The degrees of polymerization of the rice starches treated with citric acid, lactic acid or acetic acid were significantly reduced as compared to the native starches. The RS contents of acid and heat-moisture treated rice starches were in a range of 30.1-39.0%, significantly higher than those of native rice starches (6.3-10.2%) and those of heat-moisture treated rice starches (18.5-23.9%). The acid and heat-moisture treatments reduced swelling power and viscosity, but increased solubility of the starches, while the crystalline structure did not change. Among the organic acids used, citric acid had the most impact on starch characteristics and RS formation, followed by lactic acid and acetic acid. The results are useful in production of RS for functional food application. PMID:26258703

  17. The solidification and welding metallurgy of galling-resistant stainless steels

    SciTech Connect

    Robino, C.V.; Michael, J.R.; Maguire, M.C.

    1998-11-01

    The autogenous welding behavior of two commercial galling-resistant austenitic stainless steels, Nitronic 60 and Gall-Tough, was evaluated and compared. The solidification behavior and fusion zone hot-cracking tendency of the alloys was evaluated by using differential thermal analysis, Varestraint testing and laser spot-welding trials. Gleeble thermal cycle simulations were used to assess the hot ductility of the alloys during both on-heating and on-cooling portions of weld thermal cycles. Solidification microstructures were characterized by light optical and electron microscopy, and the solidification modes and phases were identified. Gas tungsten arc (GTA) welds in both alloys solidified by the ferritic-austenitic mode, and their behavior was best described using chromium and nickel equivalents developed specifically for the Nitronic series of alloys. Both alloys were found to be somewhat more susceptible to solidification hot cracking than conventional austenitic stainless steels, although the cracking resistance of Nitronic 60 was somewhat superior to Gall-Tough. Laser spot-welding trials resulted in both fusion and heat-affected zone cracking in the Nitronic 60, while Gall-Tough was resistant to cracking in these high-solidification-rate welds. Comparison of the laser weld microstructures indicated that Nitronic 60 shifts to fully austenitic solidification, while Gall-Tough shifts to an austenitic-ferritic solidification mode in high-energy-density processing. The hot ductility measurements indicated that Gall-Tough is generally superior to Nitronic 60 in both on-heating and on-cooling tests, apparently as a result of differences in grain size and the mechanism of ferrite formation at high temperatures.

  18. Heat-affected zone liquation crack on resistance spot welded TWIP steels

    SciTech Connect

    Saha, Dulal Chandra; Chang, InSung; Park, Yeong-Do

    2014-07-01

    In this study, the heat affected zone (HAZ) liquation crack and segregation behavior of the resistance spot welded twinning induced plasticity (TWIP) steel have been reported. Cracks appeared in the post-welded joints that originated at the partially melted zone (PMZ) and propagated from the PMZ through the heat affected zone (HAZ) to the base metal (BM). The crack length and crack opening widths were observed increasing with heat input; and the welding current was identified to be the most influencing parameter for crack formation. Cracks appeared at the PMZ when nugget diameter reached at 4.50 mm or above; and the liquation cracks were found to occur along two sides of the notch tip in the sheet direction rather than in the electrode direction. Cracks were backfilled with the liquid films which has lamellar structure and supposed to be the eutectic constituent. Co-segregation of alloy elements such as, C and Mn were detected on the liquid films by electron-probe microanalysis (EPMA) line scanning and element map which suggests that the liquid film was enrich of Mn and C. The eutectic constituent was identified by analyzing the calculated phase diagram along with thermal temperature history of finite element simulation. Preliminary experimental results showed that cracks have less/no significant effect on the static cross-tensile strength (CTS) and the tensile-shear strength (TSS). In addition, possible ways to avoid cracking were discussed. - Highlights: • The HAZ liquation crack during resistance spot welding of TWIP steel was examined. • Cracks were completely backfilled and healed with divorced eutectic secondary phase. • Co-segregation of C and Mn was detected in the cracked zone. • Heat input was the most influencing factor to initiate liquation crack. • Cracks have less/no significant effect on static tensile properties.

  19. Application of advanced austenitic alloys to fossil power system components

    SciTech Connect

    Swindeman, R.W.

    1996-06-01

    Most power and recovery boilers operating in the US produce steam at temperatures below 565{degrees}C (1050{degrees}F) and pressures below 24 MPa (3500 psi). For these operating conditions, carbon steels and low alloy steels may be used for the construction of most of the boiler components. Austenitic stainless steels often are used for superheater/reheater tubing when these components are expected to experience temperatures above 565{degrees}C (1050{degrees}F) or when the environment is too corrosive for low alloys steels. The austenitic stainless steels typically used are the 304H, 321H, and 347H grades. New ferritic steels such as T91 and T92 are now being introduced to replace austenitic: stainless steels in aging fossil power plants. Generally, these high-strength ferritic steels are more expensive to fabricate than austenitic stainless steels because the ferritic steels have more stringent heat treating requirements. Now, annealing requirements are being considered for the stabilized grades of austenitic stainless steels when they receive more than 5% cold work, and these requirements would increase significantly the cost of fabrication of boiler components where bending strains often exceed 15%. It has been shown, however, that advanced stainless steels developed at ORNL greatly benefit from cold work, and these steels could provide an alternative to either conventional stainless steels or high-strength ferritic steels. The purpose of the activities reported here is to examine the potential of advanced stainless steels for construction of tubular components in power boilers. The work is being carried out with collaboration of a commercial boiler manufacturer.

  20. An approach to prior austenite reconstruction

    SciTech Connect

    Abbasi, Majid; Nelson, Tracy W.; Sorensen, Carl D.; Wei Lingyun

    2012-04-15

    One area of interest in Friction Stir Welding (FSW) of steels is to understand microstructural evolution during the process. Most of the deformation occurs in the austenite temperature range. Quantitative microstructural measurements of prior austenite microstructure are needed in order to understand evolution of the microstructure. Considering the fact that room temperature microstructure in ferritic steels contains very little to no retained austenite, prior austenite microstructure needs to be recovered from the room temperature ferrite. In this paper, an approach based on Electron Backscattered Diffraction (EBSD) is introduced to detect Bain zones. Bain zone detection is used to reconstruct prior austenite grain structure. Additionally, a separate approach based on phase transformation orientation relationships is introduced in order to recover prior austenite orientation. - Highlights: Black-Right-Pointing-Pointer This approach provides a tool to reconstruct large-scale austenite microstructures. Black-Right-Pointing-Pointer It recovers prior austenite orientation without relying on retained austenite. Black-Right-Pointing-Pointer It utilizes EBSD data from the room temperature microstructure. Black-Right-Pointing-Pointer Higher number of active variants leads to more accurate reconstructions. Black-Right-Pointing-Pointer At least two variants are needed in order to recover prior austenite orientation.

  1. Effects of cooling time and alloying elements on the microstructure of the gleeble-simulated heat-affected zone of 22% Cr duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Hsieh, Rong-Iuan; Liou, Horng-Yih; Pan, Yeong-Tsuen

    2001-10-01

    The effects of austenite stabilizers, such as nitrogen, nickel, and manganese, and cooling time on the microstructure of the Gleeble simulated heat-affected zone (HAZ) of 22% Cr duplex stainless steels were investigated. The submerged are welding was performed for comparison purposes. Optical microscopy (OM) and transmission electron microscopy (TEM) were used for microscopic studies. The amount of Cr2N precipitates in the simulated HAZ was determined using the potentiostatic electrolysis method. The experimental results indicate that an increase in the nitrogen and nickel contents raised the δ to transformation temperature and also markedly increased the amount of austenite in the HAZ. The lengthened cooling time promotes the reformation of austenite. An increase in the austenite content reduces the supersaturation of nitrogen in ferrite matrix as well as the precipitation tendency of Cr2N. The optimum cooling time from 800 to 500 °C (Δ t 8/5) obtained from the Gleeble simulation is between 30 and 60 s, which ensures the austenite content in HAZ not falling below 25% and superior pitting and stress corrosion cracking resistance for the steels. The effect of manganese on the formation of austenite can be negligible.

  2. Rapid embedded wire heating via resistive guiding of laser-generated fast electrons as a hydrodynamic driver

    SciTech Connect

    Robinson, A. P. L.; Schmitz, H.; Pasley, J.

    2013-12-15

    Resistively guiding laser-generated fast electron beams in targets consisting of a resistive wire embedded in lower Z material should allow one to rapidly heat the wire to over 100 eV over a substantial distance without strongly heating the surrounding material. On the multi-ps timescale, this can drive hydrodynamic motion in the surrounding material. Thus, ultra-intense laser solid interactions have the potential as a controlled driver of radiation hydrodynamics in solid density material. In this paper, we assess the laser and target parameters needed to achieve such rapid and controlled heating of the embedded wire.

  3. Polymorphisms of heat shock protein 90 (Hsp90) in the sea cucumber Apostichopus japonicus and their association with heat-resistance.

    PubMed

    Xu, Dongxue; Sun, Lina; Liu, Shilin; Zhang, Libin; Yang, Hongsheng

    2014-12-01

    Heat shock protein 90 (Hsp90) functions as a molecular chaperone and plays an important role in the resistance of organisms to stress, particularly heat-stress. In our study, 12 exons and 11 introns of hsp90 were identified in the sea cucumber Apostichopus japonicus. Twenty-two single nucleotide polymorphisms (SNPs), including three non-synonymous mutations, were detected in the exons. Susceptible and resistant individuals were distinguished using a high-temperature (32 °C) challenge experiment. Three blocks with high linkage disequilibrium were detected among these SNPs. Five of the twenty-two SNPs were shown to be significantly associated with susceptibility/resistance to high temperature by correlation analysis (chi-square test, P < 0.05). To confirm the importance of these five SNPs, a heat-resistance strain (HRS) was selected through three generations. Using the common population as the control group, it was shown that the distributions of genotypes and alleles of SNP e10-1 and e11-6 were significantly different between the two groups (P < 0.05). SNP e10-1 was trimorphic, with three alleles (A, C and T) and five genotypes (AA, CC, AT, CT and AC). The allele frequency of SNP e2-3 was also significantly associated with this trait (P < 0.05). This is the first demonstration of SNPs related to heat-resistance in A. japonicus and supports the use of SNP markers in the selective breeding of sea cucumbers. PMID:25270529

  4. Multiple pulse-heating experiments with different current to determine total emissivity, heat capacity, and electrical resistivity of electrically conductive materials at high temperatures.

    PubMed

    Watanabe, Hiromichi; Yamashita, Yuichiro

    2012-01-01

    A modified pulse-heating method is proposed to improve the accuracy of measurement of the hemispherical total emissivity, specific heat capacity, and electrical resistivity of electrically conductive materials at high temperatures. The proposed method is based on the analysis of a series of rapid resistive self-heating experiments on a sample heated at different temperature rates. The method is used to measure the three properties of the IG-110 grade of isotropic graphite at temperatures from 850 to 1800 K. The problem of the extrinsic heating-rate effect, which reduces the accuracy of the measurements, is successfully mitigated by compensating for the generally neglected experimental error associated with the electrical measurands (current and voltage). The results obtained by the proposed method can be validated by the linearity of measured quantities used in the property determinations. The results are in reasonably good agreement with previously published data, which demonstrate the suitability of the proposed method, in particular, to the resistivity and total emissivity measurements. An interesting result is the existence of a minimum in the emissivity of the isotropic graphite at around 1120 K, consistent with the electrical resistivity results. PMID:22299976

  5. Mi-1-Mediated Nematode Resistance in Tomatoes is Broken by Short-Term Heat Stress but Recovers Over Time.

    PubMed

    Marques de Carvalho, Luciana; Benda, Nicole D; Vaughan, Martha M; Cabrera, Ana R; Hung, Kaddie; Cox, Thomas; Abdo, Zaid; Allen, L Hartwell; Teal, Peter E A

    2015-06-01

    Tomato (Solanum lycopersicum L.) is among the most valuable agricultural products, but Meloidogyne spp. (root-knot nematode) infestations result in serious crop losses. In tomato, resistance to root-knot nematodes is controlled by the gene Mi-1, but heat stress interferes with Mi-1-associated resistance. Inconsistent results in published field and greenhouse experiments led us to test the effect of short-term midday heat stress on tomato susceptibility to Meloidogyne incognita race 1. Under controlled day/night temperatures of 25°C/21°C, 'Amelia', which was verified as possessing the Mi-1 gene, was deemed resistant (4.1 ± 0.4 galls/plant) and Rutgers, which does not possess the Mi-1 gene, was susceptible (132 ± 9.9 galls/plant) to M. incognita infection. Exposure to a single 3 hr heat spike of 35°C was sufficient to increase the susceptibility of 'Amelia' but did not affect Rutgers. Despite this change in resistance, Mi-1 gene expression was not affected by heat treatment, or nematode infection. The heat-induced breakdown of Mi-1 resistance in 'Amelia' did recover with time regardless of additional heat exposures and M. incognita infection. These findings would aid in the development of management strategies to protect the tomato crop at times of heightened M. incognita susceptibility. PMID:26170475

  6. Mi-1-Mediated Nematode Resistance in Tomatoes is Broken by Short-Term Heat Stress but Recovers Over Time

    PubMed Central

    Marques de Carvalho, Luciana; Benda, Nicole D.; Vaughan, Martha M.; Cabrera, Ana R.; Hung, Kaddie; Cox, Thomas; Abdo, Zaid; Allen, L. Hartwell; Teal, Peter E. A.

    2015-01-01

    Tomato (Solanum lycopersicum L.) is among the most valuable agricultural products, but Meloidogyne spp. (root-knot nematode) infestations result in serious crop losses. In tomato, resistance to root-knot nematodes is controlled by the gene Mi-1, but heat stress interferes with Mi-1-associated resistance. Inconsistent results in published field and greenhouse experiments led us to test the effect of short-term midday heat stress on tomato susceptibility to Meloidogyne incognita race 1. Under controlled day/night temperatures of 25°C/21°C, ‘Amelia’, which was verified as possessing the Mi-1 gene, was deemed resistant (4.1 ± 0.4 galls/plant) and Rutgers, which does not possess the Mi-1 gene, was susceptible (132 ± 9.9 galls/plant) to M. incognita infection. Exposure to a single 3 hr heat spike of 35°C was sufficient to increase the susceptibility of ‘Amelia’ but did not affect Rutgers. Despite this change in resistance, Mi-1 gene expression was not affected by heat treatment, or nematode infection. The heat-induced breakdown of Mi-1 resistance in ‘Amelia’ did recover with time regardless of additional heat exposures and M. incognita infection. These findings would aid in the development of management strategies to protect the tomato crop at times of heightened M. incognita susceptibility. PMID:26170475

  7. Weldability of neutron irradiated austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Asano, Kyoichi; Nishimura, Seiji; Saito, Yoshiaki; Sakamoto, Hiroshi; Yamada, Yuji; Kato, Takahiko; Hashimoto, Tsuneyuki

    1999-01-01

    Degradation of weldability in neutron irradiated austenitic stainless steel is an important issue to be addressed in the planning of proactive maintenance of light water reactor core internals. In this work, samples selected from reactor internal components which had been irradiated to fluence from 8.5 × 10 22 to 1.4 × 10 26 n/m 2 ( E > 1 MeV) corresponding to helium content from 0.11 to 103 appm, respectively, were subjected to tungsten inert gas arc (TIG) welding with heat input ranged 0.6-16 kJ/cm. The weld defects were characterized by penetrant test and cross-sectional metallography. The integrity of the weld was better when there were less helium and at lower heat input. Tensile properties of weld joint containing 0.6 appm of helium fulfilled the requirement for unirradiated base metal. Repeated thermal cycles were found to be very hazardous. The results showed the combination of material helium content and weld heat input where materials can be welded with little concern to invite cracking. Also, the importance of using properly selected welding procedures to minimize thermal cycling was recognized.

  8. Oxidation, carburization and/or sulfidation resistant iron aluminide alloy

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    2003-08-19

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or Zro.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B. .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  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. Heat-resistant organic molecular layer as a joint interface for metal reduction on plastics surfaces

    NASA Astrophysics Data System (ADS)

    Sang, Jing; Aisawa, Sumio; Hirahara, Hidetoshi; Kudo, Takahiro; Mori, Kunio

    2016-04-01

    Heat-resistant organic molecular layers have been fabricated by triazine-based silane coupling agent for metal reduction on plastic surfaces using adsorption method. These molecular layers were used as an interfacial layer between polyamide (PA6) and metal solution to reduce Ag+ ion to Ag0. The interfacial behaviors of triazine molecular layer at the interfaces between PA6 and Ag solution were investigated using quartz crystal microbalance (QCM). The kinetics of molecular adsorption on PA6 was investigated by using triazine-based silane coupling agent solutions at different pH and concentration. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and local nano thermal analysis were employed to characterize the surfaces and interfaces. The nano thermal analysis results show that molecular layers of triazine-based silane coupling agent greatly improved heat resistance of PA6 resin from 170 °C up to 230 °C. This research developed an in-depth insight for molecular behaviors of triazine-based silane coupling agent at the PA6 and Ag solution interfaces and should be of significant value for interfacial research between plastics and metal solution in plating industry.

  11. Plasmonic Heating in Au Nanowires at Low Temperatures: The Role of Thermal Boundary Resistance.

    PubMed

    Zolotavin, Pavlo; Alabastri, Alessandro; Nordlander, Peter; Natelson, Douglas

    2016-07-26

    Inelastic electron tunneling and surface-enhanced optical spectroscopies at the molecular scale require cryogenic local temperatures even under illumination-conditions that are challenging to achieve with plasmonically resonant metallic nanostructures. We report a detailed study of the laser heating of plasmonically active nanowires at substrate temperatures from 5 to 60 K. The increase of the local temperature of the nanowire is quantified by a bolometric approach and could be as large as 100 K for a substrate temperature of 5 K and typical values of laser intensity. We also demonstrate that a ∼3-fold reduction of the local temperature increase is possible by switching to a sapphire or quartz substrate. Finite element modeling of the heat dissipation reveals that the local temperature increase of the nanowire at temperatures below ∼50 K is determined largely by the thermal boundary resistance of the metal-substrate interface. The model reproduces the striking experimental trend that in this regime the temperature of the nanowire varies nonlinearly with the incident optical power. The thermal boundary resistance is demonstrated to be a major constraint on reaching low temperatures necessary to perform simultaneous inelastic electron tunneling and surface-enhanced Raman spectroscopies. PMID:27355238

  12. Analysis Of Post-Wet-Chemistry Heat Treatment Effects On Nb SRF Surface Resistance

    SciTech Connect

    Dhakal, Pashupati; Ciovati, Gianluigi; Kneisel, Peter K.; Myneni, Ganapati Rao

    2014-02-01

    Most of the current research in superconducting radio frequency (SRF) cavities is focused on ways to reduce the construction and operating cost of SRF-based accelerators as well as on the development of new or improved cavity processing techniques. The increase in quality factors is the result of the reduction of the surface resistance of the materials. A recent test on a 1.5 GHz single cell cavity made from ingot niobium of medium purity and heat treated at 1400 deg C in a ultra-high vacuum induction furnace resulted in a residual resistance of ~ 1n{Omega} and a quality factor at 2.0 K increasing with field up to ~ 5×10{sup 10} at a peak magnetic field of 90 mT. In this contribution, we present some results on the investigation of the origin of the extended Q{sub 0}-increase, obtained by multiple HF rinses, oxypolishing and heat treatment of all Nb cavities.

  13. Factors affecting gas migration and contaminant redistribution in heterogeneous porous media subject to electrical resistance heating

    NASA Astrophysics Data System (ADS)

    Munholland, Jonah L.; Mumford, Kevin G.; Kueper, Bernard H.

    2016-01-01

    A series of intermediate-scale laboratory experiments were completed in a two-dimensional flow cell to investigate gas production and migration during the application of electrical resistance heating (ERH) for the removal of dense non-aqueous phase liquids (DNAPLs). Experiments consisted of heating water in homogeneous silica sand and heating 270 mL of trichloroethene (TCE) and chloroform (CF) DNAPL pools in heterogeneous silica sands, both under flowing groundwater conditions. Spatial and temporal distributions of temperature were measured using thermocouples and observations of gas production and migration were collected using front-face image capture throughout the experiments. Post-treatment soil samples were collected and analyzed to assess DNAPL removal. Results of experiments performed in homogeneous sand subject to different groundwater flow rates showed that high groundwater velocities can limit subsurface heating rates. In the DNAPL pool experiments, temperatures increased to achieve DNAPL-water co-boiling, creating estimated gas volumes of 131 and 114 L that originated from the TCE and CF pools, respectively. Produced gas migrated vertically, entered a coarse sand lens and subsequently migrated laterally beneath an overlying capillary barrier to outside the heated treatment zone where 31-56% of the original DNAPL condensed back into a DNAPL phase. These findings demonstrate that layered heterogeneity can potentially facilitate the transport of contaminants outside the treatment zone by mobilization and condensation of gas phases during ERH applications. This underscores the need for vapor phase recovery and/or control mechanisms below the water table during application of ERH in heterogeneous porous media during the co-boiling stage, which occurs prior to reaching the boiling point of water.

  14. Factors affecting gas migration and contaminant redistribution in heterogeneous porous media subject to electrical resistance heating.

    PubMed

    Munholland, Jonah L; Mumford, Kevin G; Kueper, Bernard H

    2016-01-01

    A series of intermediate-scale laboratory experiments were completed in a two-dimensional flow cell to investigate gas production and migration during the application of electrical resistance heating (ERH) for the removal of dense non-aqueous phase liquids (DNAPLs). Experiments consisted of heating water in homogeneous silica sand and heating 270 mL of trichloroethene (TCE) and chloroform (CF) DNAPL pools in heterogeneous silica sands, both under flowing groundwater conditions. Spatial and temporal distributions of temperature were measured using thermocouples and observations of gas production and migration were collected using front-face image capture throughout the experiments. Post-treatment soil samples were collected and analyzed to assess DNAPL removal. Results of experiments performed in homogeneous sand subject to different groundwater flow rates showed that high groundwater velocities can limit subsurface heating rates. In the DNAPL pool experiments, temperatures increased to achieve DNAPL-water co-boiling, creating estimated gas volumes of 131 and 114 L that originated from the TCE and CF pools, respectively. Produced gas migrated vertically, entered a coarse sand lens and subsequently migrated laterally beneath an overlying capillary barrier to outside the heated treatment zone where 31-56% of the original DNAPL condensed back into a DNAPL phase. These findings demonstrate that layered heterogeneity can potentially facilitate the transport of contaminants outside the treatment zone by mobilization and condensation of gas phases during ERH applications. This underscores the need for vapor phase recovery and/or control mechanisms below the water table during application of ERH in heterogeneous porous media during the co-boiling stage, which occurs prior to reaching the boiling point of water. PMID:26638038

  15. In-situ determination of austenite and martensite formation in 13Cr6Ni2Mo supermartensitic stainless steel

    SciTech Connect

    Bojack, A.; Zhao, L.; Morris, P.F.; Sietsma, J.

    2012-09-15

    In-situ analysis of the phase transformations in a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) was carried out using a thermo-magnetic technique, dilatometry and high temperature X-ray diffractometry (HT-XRD). A combination of the results obtained by the three applied techniques gives a valuable insight in the phase transformations during the austenitization treatment, including subsequent cooling, of the 13Cr6Ni2Mo supermartensitic stainless steel, where the magnetic technique offers a high accuracy in monitoring the austenite fraction. It was found by dilatometry that the austenite formation during heating takes place in two stages, most likely caused by partitioning of Ni into austenite. The in-situ evolution of the austenite fraction is monitored by high-temperature XRD and dilatometry. The progress of martensite formation during cooling was described with a Koistinen-Marburger relation for the results obtained from the magnetic and dilatometer experiments. Enhanced martensite formation at the sample surface was detected by X-ray diffraction, which is assumed to be due to relaxation of transformation stresses at the sample surface. Due to the high alloy content and high thermodynamic stability of austenite at room temperature, 4 vol.% of austenite was found to be stable at room temperature after the austenitization treatment. - Highlights: Black-Right-Pointing-Pointer We in-situ analyzed phase transformations and fractions of a 13Cr6Ni2Mo SMSS. Black-Right-Pointing-Pointer Higher accuracy of the austenite fraction was obtained from magnetic technique. Black-Right-Pointing-Pointer Austenite formation during heating takes place in two stages. Black-Right-Pointing-Pointer Enhanced martensite formation at the sample surface detected by X-ray diffraction.

  16. Preparation and characterization of Fe-Al intermetallic layer on the surface of T91 heat-resistant steel

    NASA Astrophysics Data System (ADS)

    Shi, Zimu; Cao, Jianbo; Han, Fusheng

    2014-04-01

    A Fe-Al intermetallic layer was formed on the surface of T91 heat-resistant steel by a molten aluminum hot-dipping and heat diffusion treatment. It is shown that the layer was composed of Al, FeAl3 and Fe2Al5 phases in the as-dipped state while only Fe3Al phase retained after the heat treatment. The intermetallic layer exhibited typical columnar grain structure after the heat treatment, and the thickness of aluminizing layer was increased from 55 μm at 760 °C to around 100 μm at 1050 °C heat treatment. Such a phase composition and grain morphology are favorable for the oxidation and corrosion resistance of T91 steel.

  17. Microstructural evolution and mechanical properties of a low-carbon quenching and partitioning steel after partial and full austenitization

    NASA Astrophysics Data System (ADS)

    Li, Wan-song; Gao, Hong-ye; Nakashima, Hideharu; Hata, Satoshi; Tian, Wen-huai

    2016-08-01

    In this work, low-carbon steel specimens were subjected to the quenching and partitioning process after being partially or fully austenitized to investigate their microstructural evolution and mechanical properties. According to the results of scanning electron microscopy and transmission electron microscopy observations, X-ray diffraction analysis, and tensile tests, upper bainite or tempered martensite appears successively in the microstructure with increasing austenitization temperature or increasing partitioning time. In the partially austenitized specimens, the retained austenite grains are carbon-enriched twice during the heat treatment, which can significantly stabilize the phases at room temperature. Furthermore, after partial austenitization, the specimen exhibits excellent elongation, with a maximum elongation of 37.1%. By contrast, after full austenitization, the specimens exhibit good ultimate tensile strength and high yield strength. In the case of a specimen with a yield strength of 969 MPa, the maximum value of the ultimate tensile strength reaches 1222 MPa. During the partitioning process, carbon partitioning and carbon homogenization within austenite affect interface migration. In addition, the volume fraction and grain size of retained austenite observed in the final microstructure will also be affected.

  18. Surface modification of austenitic thermal-spray coatings by low-temperature nitrocarburizing

    NASA Astrophysics Data System (ADS)

    Lindner, T.; Mehner, T.; Lampke, T.

    2016-03-01

    Thermal-spray coatings of austenitic materials are mainly used under corrosive conditions. The relatively poor wear resistance strongly limits their use. In comparative studies between nitrocarburized and untreated thermal-spray coatings, the influence of the nitrogen and carbon enrichment on the properties of the coatings and the microstructure was investigated. The cross-section micrograph of the nitrocarburized coating shows the S-phase formation in the surface layer region. The depth profile of the nitrogen and carbon concentration was determined by glow discharge optical emission spectroscopy (GDOS) analysis. A selective enrichment of the surface layer region with nitrogen and carbon by means of thermochemical heat treatment increases the wear resistance. The interstitially dissolved nitrogen and carbon causes the formation of strong compressive residual stresses and high surface hardness. Increases in the service life of existing applications or new material combinations with face-centred cubic friction partners are possible. In the absence of dimensional change, uniform as well as partial nitrogen enrichment of the thermal spray coating is possible. Nitrocarburized coatings demonstrate a significant improvement in adhesive wear resistance and extremely high surface hardness.

  19. Resistively-Heated Microlith-based Adsorber for Carbon Dioxide and Trace Contaminant Removal

    NASA Technical Reports Server (NTRS)

    Roychoudhury, S.; Walsh, D.; Perry, J.

    2005-01-01

    An integrated sorber-based Trace Contaminant Control System (TCCS) and Carbon Dioxide Removal Assembly (CDRA) prototype was designed, fabricated and tested. It corresponds to a 7-person load. Performance over several adsorption/regeneration cycles was examined. Vacuum regenerations at effective time/temperature conditions, and estimated power requirements were experimentally verified for the combined CO2/trace contaminant removal prototype. The current paper details the design and performance of this prototype during initial testing at CO2 and trace contaminant concentrations in the existing CDRA, downstream of the drier. Additional long-term performance characterization is planned at NASA. Potential system design options permitting associated weight, volume savings and logistic benefits, especially as relevant for long-duration space flight, are reviewed. The technology consisted of a sorption bed with sorbent- coated metal meshes, trademarked and patented as Microlith by Precision Combustion, Inc. (PCI). By contrast the current CO2 removal system on the International Space Station employs pellet beds. Preliminary bench scale performance data (without direct resistive heating) for simultaneous CO2 and trace contaminant removal was reviewed in SAE 2004-01-2442. In the prototype, the meshes were directly electrically heated for rapid response and accurate temperature control. This allowed regeneration via resistive heating with the potential for shorter regeneration times, reduced power requirement, and net energy savings vs. conventional systems. A novel flow arrangement, for removing both CO2 and trace contaminants within the same bed, was demonstrated. Thus, the need for a separate trace contaminant unit was eliminated resulting in an opportunity for significant weight savings. Unlike the current disposable charcoal bed, zeolites for trace contaminant removal are amenable to periodic regeneration.

  20. Arabidopsis HEAT SHOCK TRANSCRIPTION FACTORA1b overexpression enhances water productivity, resistance to drought, and infection.

    PubMed

    Bechtold, Ulrike; Albihlal, Waleed S; Lawson, Tracy; Fryer, Michael J; Sparrow, Penelope A C; Richard, François; Persad, Ramona; Bowden, Laura; Hickman, Richard; Martin, Cathie; Beynon, Jim L; Buchanan-Wollaston, Vicky; Baker, Neil R; Morison, James I L; Schöffl, Friedrich; Ott, Sascha; Mullineaux, Philip M

    2013-08-01

    Heat-stressed crops suffer dehydration, depressed growth, and a consequent decline in water productivity, which is the yield of harvestable product as a function of lifetime water consumption and is a trait associated with plant growth and development. Heat shock transcription factor (HSF) genes have been implicated not only in thermotolerance but also in plant growth and development, and therefore could influence water productivity. Here it is demonstrated that Arabidopsis thaliana plants with increased HSFA1b expression showed increased water productivity and harvest index under water-replete and water-limiting conditions. In non-stressed HSFA1b-overexpressing (HSFA1bOx) plants, 509 genes showed altered expression, and these genes were not over-represented for development-associated genes but were for response to biotic stress. This confirmed an additional role for HSFA1b in maintaining basal disease resistance, which was stress hormone independent but involved H₂O₂ signalling. Fifty-five of the 509 genes harbour a variant of the heat shock element (HSE) in their promoters, here named HSE1b. Chromatin immunoprecipitation-PCR confirmed binding of HSFA1b to HSE1b in vivo, including in seven transcription factor genes. One of these is MULTIPROTEIN BRIDGING FACTOR1c (MBF1c). Plants overexpressing MBF1c showed enhanced basal resistance but not water productivity, thus partially phenocopying HSFA1bOx plants. A comparison of genes responsive to HSFA1b and MBF1c overexpression revealed a common group, none of which harbours a HSE1b motif. From this example, it is suggested that HSFA1b directly regulates 55 HSE1b-containing genes, which control the remaining 454 genes, collectively accounting for the stress defence and developmental phenotypes of HSFA1bOx. PMID:23828547

  1. 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.

  2. Sterol Biosynthesis Is Required for Heat Resistance but Not Extracellular Survival in Leishmania

    PubMed Central

    Xu, Wei; Hsu, Fong-Fu; Baykal, Eda; Huang, Juyang; Zhang, Kai

    2014-01-01

    Sterol biosynthesis is a crucial pathway in eukaryotes leading to the production of cholesterol in animals and various C24-alkyl sterols (ergostane-based sterols) in fungi, plants, and trypanosomatid protozoa. Sterols are important membrane components and precursors for the synthesis of powerful bioactive molecules, including steroid hormones in mammals. Their functions in pathogenic protozoa are not well characterized, which limits the development of sterol synthesis inhibitors as drugs. Here we investigated the role of sterol C14α-demethylase (C14DM) in Leishmania parasites. C14DM is a cytochrome P450 enzyme and the primary target of azole drugs. In Leishmania, genetic or chemical inactivation of C14DM led to a complete loss of ergostane-based sterols and accumulation of 14-methylated sterols. Despite the drastic change in lipid composition, C14DM-null mutants (c14dm−) were surprisingly viable and replicative in culture. They did exhibit remarkable defects including increased membrane fluidity, failure to maintain detergent resistant membrane fraction, and hypersensitivity to heat stress. These c14dm− mutants showed severely reduced virulence in mice but were highly resistant to itraconazole and amphotericin B, two drugs targeting sterol synthesis. Our findings suggest that the accumulation of toxic sterol intermediates in c14dm− causes strong membrane perturbation and significant vulnerability to stress. The new knowledge may help improve the efficacy of current drugs against pathogenic protozoa by exploiting the fitness loss associated with drug resistance. PMID:25340392

  3. Mechanically alloyed Ni-base alloys for heat-resistant applications

    SciTech Connect

    Wilson, R.K.; Fischer, J.J.

    1995-12-31

    INCONEL alloys MA 754 and MA 758 are nickel-base oxide dispersion-strengthened (ODS) alloys made by mechanical alloying (MA). Commercial use of Ma Ni-base alloys to date has been predominantly in aerospace applications of alloy MA 754 as turbine engine vanes. Both alloys are suitable for industrial heat treating components and other heat resistant alloy applications. Field trials and commercial experience in such applications of MA alloys are being gained while high temperature property characterization and new product form development continue. Hot isostatic pressing (HIP) is the standard consolidation method for billets from which large bar and plate are produced for industrial applications of MA. This paper describes production of standard mill shapes from HIP billets, and it presents information on current and potential uses of MA alloys in applications such as: skid rails for use in high temperature walking beam furnaces, heat treating furnace components, components for handling molten glass, and furnace tubes. The paper includes comparison of the properties obtained in alloy MA 754 (20% Cr) and alloy MA 758 (30% Cr).

  4. The Application of Low Temperature Electrical Resistance Heating for Subsurface Remediation

    NASA Astrophysics Data System (ADS)

    Krol, M. M.; Sleep, B. E.; Johnson, R. L.

    2009-12-01

    Electrical Resistance Heating (ERH) is an innovative remediation technology for sites contaminated with chlorinated solvents. ERH enhances contaminant removal by heating the subsurface and changing the vapor pressures, viscosities, and densities of contaminants as well as water. While ERH is most-commonly applied at temperatures above the boiling point of water, significantly less energy is required if temperatures can be kept at sub-boiling levels. However, it is not clear how this impacts remediation effectiveness. In addition, for applications such as geothermal heating, understanding the impact of temperature gradients on water flow distribution in different subsurface settings is important. To study these issues, a two-dimensional (2D) finite difference electro-thermal model was developed. To evaluate the model, a 2D tank experiment (55 cm x 42 cm x 1.8 cm) was used that reproduced a two-phase ERH set-up using 12 electrodes. Temperature measurements were collected using 48 thermocouples and tracer injection was used to examine the change in water flow due to increased temperature. Significant buoyant flow was observed through the heated zone. The electro-thermal model successfully simulated the experimental observations of temperature distribution in the tank, mass transport, as well as power consumption. To examine the effect of subsurface geology on heat and contaminant distribution, sixteen cases with different soil permeabilities and inlet velocities were modeled using low temperature (50°C) ERH and compared to non heated and higher temperature (80°C) scenarios. Buoyancy and viscosity effects were found to enhance the movement and distribution of contaminants under certain permeability/velocity scenarios by increasing the velocity through the contaminated zone, decreasing mass depletion times. In scenarios with either low permeability or high hydraulic gradients, buoyancy effects had no effect on mass movement. To differentiate between these cases, a

  5. Effects of early age feed restriction and heat conditioning on heat shock protein 70 expression, resistance to infectious bursal disease, and growth in male broiler chickens subjected to heat stress.

    PubMed

    Liew, P K; Zulkifli, I; Hair-Bejo, M; Omar, A R; Israf, D A

    2003-12-01

    The effects of early age feed restriction and heat conditioning on heat shock protein (HSP) 70 expression, antibody production, resistance to infectious bursal disease (IBD), and growth of heat-stressed male broiler chickens were investigated. Chicks were divided into 4 groups: 60% feed restriction on d 4,5, and 6 (FR); exposure to 36 +/- 1 degrees C for 1 h from d 1 to 21 (HT); combination of FR and HT (FRHT); and control. From d 35 to 50, heat stress was induced by exposing birds to 38 +/- 1 degrees C and 80% RH for 2 h/d. On d 36, each bird was administered 10 times the normal dose of live IBD vaccine. After heat exposure, the FRHT birds had higher HSP 70 density (d 41) and weight gain (from d 35 to 49) and lower bursal histological score (BHS) (d 51) than their HT and control counterparts. The HSP 70 expression and BHS of FR birds were not significantly different from those of the other 3 groups during the heat exposure period. Heat shock protein 70 and BHS data were negatively correlated (r = -0.33, P = 0.0008). We concluded that FRHT could improve weight gain and resistance to IBD in male broiler chickens under heat stress conditions. The improved heat tolerance and disease resistance in FRHT birds could be attributed to better HSP 70 response. PMID:14717545

  6. Stages of austenitization of cold-worked low-carbon steel in intercritical temperature range

    NASA Astrophysics Data System (ADS)

    Panov, D. O.; Simonov, Y. N.; Spivak, L. V.; Smirnov, A. I.

    2015-08-01

    Austenization processes in 10Kh3G3MF low-carbon steel in the initially cold-worked state are investigated during its continuous heating in an intercritical temperature range. The austenization of this steel has three stages, which is shown by dilatometry, differential scanning calorimetry, and transmission electron microscopy. The thermokinetic diagram of the austenite formation in 10Kh3G3MF steel is constructed. Critical points A c1 and A c2 and temperature ranges of austenite formation at every stage of the α → γ transformation at heating rates of 0.6-400 K/s are determined.

  7. Empirical analysis of contributing factors to heating in lithium-ion cells: Anode entropy versus internal resistance

    NASA Astrophysics Data System (ADS)

    Srinivasan, Rengaswamy; Carkhuff, Bliss G.

    2013-11-01

    Charging a battery beyond its maximum capacity can lead both to cell overheating and to the venting of gasses. A fundamental understanding of cell heating could lead to the development of real-time sensors that anticipate and avert catastrophic battery failure. Joule heating (also called ohmic or resistive heating) from cell internal resistance (Rint) dominates the overall thermal energy (ΔQ) generated during charging. Contrary to prior hypotheses, though, Joule heating does not appear to contribute to venting observed during overcharging. In this manuscript, we examine an alternate hypothesis, that heat released by the entropy change in the anode (ΔSanode) and the concomitant increase in the anode temperature (Tanode) triggers the venting. Using our recently developed non-invasive battery internal temperature (BIT) sensor to monitor Tanode, we separated the contributions of ΔSanode, Rint and the anode resistance (Ranode) to ΔQ. These quantities were tracked during constant current charging of a 18650 Lithium-ion cell, from zero state of charge (SoC) to overcharge. The resulting analysis suggests that anode entropy change is more important than resistive heating resulting from Ranode to the overall thermal energy. Anode entropy measurements, enabled by the BIT sensor, might serve as an alternative or adjunct method for anticipating and avoiding cell venting events.

  8. Microsecond Time-Resolved Pyrometry during Rapid Resistive Heating of Samples in a Kolsky Bar Apparatus

    NASA Astrophysics Data System (ADS)

    Basak, D.; Yoon, H. W.; Rhorer, R.; Burns, T.

    2003-09-01

    Analysis of machining processes is important in the understanding and improving of manufacturing methods. The modeling of machining processes relies on high-strain rate, high-temperature material properties. A split-Hopkinson pressure bar (or Kolsky bar) is being installed in a NIST high-current pulse-heating facility. By heating the material sample rapidly with a controlled current pulse immediately before the mechanical impact in the bar, structural changes in the sample are inhibited, thus better simulating conditions during machining. A stress-strain relationship can be determined at various temperatures for test materials. We describe the design and the development of a millisecond-resolution split-Hopkinson apparatus, where the sample is resistively heated by the passage of a sub-second-duration electric current pulse. The impact bar is constructed out of maraging steel and the sample is a cylinder of AISI 1045 steel. The current is transmitted through the oiled-bronze sleeve bushing of the impact bar. The temperature measurements are performed using a near-infrared micro-pyrometer (NIMPY). The NIMPY consists of a refractive 5× microscope objective with a numerical aperture of 0.14 attached to a traditional microscope body. The thermal measurement is performed with an InGaAs detector with ˜ 1 μs response time. The procedure used to calibrate the pyrometer with a variable temperature blackbody is described. A brief description of a model of the pulse heating process is given and the predicted sample temperature history is compared with measured temperature data.

  9. Direct decomposition of austenite in two Fe-V-C alloys

    NASA Astrophysics Data System (ADS)

    Mishima, Y.; Horn, R. M.; Zackay, V. F.; Parker, E. R.

    1980-03-01

    Investigations of austenite decomposition have been undertaken in (1) Fe-0.5Mn-1V-0.2C and (2) Fe-0.5Mn-3Ni-1V-0.2C alloys. Isothermal transformation characteristics were determined using dilatometric and thermo-electric potential techniques. Also, micro-structural features were observed using optical and transmission electron microscopy for treatments of interest following isothermal austenite decomposition in the 550 to 750° C range. Associated mechanical properties were measured with emphasis being placed on Charpy impact behavior. Both alloys exhibited two temperature regions in which “C-curve” austenite decomposition occurred. In the upper region a combination of fibrous and fine particle VC precipitation was observed in both alloys. In the lower transformation region, bainitic microstructures resulted from the isothermal treatments. Additionally, the alloy containing 3 pct Ni exhibited VC precipitation in the austenite prior to ferrite formation. In both alloys, complete isothermal transformation produced microstructures with poor impact properties. However, a good combination of strength and toughness was produced in the 3 pct Ni alloy using the heat treatment that promoted VC precipitation in austenite but avoided total isothermal austenite decomposition.

  10. The composition of precipitated austenite in 5.5ni steel

    NASA Astrophysics Data System (ADS)

    Kim, J. I.; Morris, J. W.

    1981-11-01

    Both scanning transmission electron microscopic (STEM) and chemical extraction techniques were used to analyze the chemical content of precipitated austenite in 5.5Ni steel as a function of heat treatment. Austenite was introduced into the steel by tempering at 600 °C for 2 h (QT2) or 100 h (QT100), by tempering for 1 h at 670 °C (QL), or by double tempering 1 h at 670 °C + 1 h at 600 °C (QLT). The two methods of chemical analysis employed for the analysis of this austenite differ quantitatively in the measured austenite composition but are in qualitative agreement; they show an austenite enrichment in Ni, Cr, Mn, and Mo which is most pronounced (and nearly equivalent) for the QT100 and QLT treatments. The similar enrichment of the QT100 and QLT material is interpreted in light of the sequence of reactions leading to the QLT structure. A good correlation is found between the apparent solute enrichment of the precipitated austenite and its thermal stability on cooling to 77 K.

  11. Tailoring plasticity of austenitic stainless steels for nuclear applications: Review of mechanisms controlling plasticity of austenitic steels below 400 °C

    NASA Astrophysics Data System (ADS)

    Meric de Bellefon, G.; van Duysen, J. C.

    2016-07-01

    AISI 304 and 316 austenitic stainless steels were invented in the early 1900s and are still trusted by materials and mechanical engineers in numerous sectors because of their good combination of strength, ductility, and corrosion resistance, and thanks to decades of experience and data. This article is part of an effort focusing on tailoring the plasticity of both types of steels to nuclear applications. It provides a synthetic and comprehensive review of the plasticity mechanisms in austenitic steels during tensile tests below 400 °C. In particular, formation of twins, extended stacking faults, and martensite, as well as irradiation effects and grain rotation are discussed in details.

  12. Thermal, epithermal and thermalized neutron attenuation properties of ilmenite-serpentine heat resistant concrete shield

    NASA Astrophysics Data System (ADS)

    Kany, A. M. I.; El-Gohary, M. I.; Kamal, S. M.

    1994-07-01

    Experimental measurements were carried out to study the attenuation properties of low-energy neutrons transmitted through unheated and preheated barries of heavy-weight, highly hydrated and heat-resistant concrete shields. The concrete shields under investigation have been prepared from naturally occurring ilmenite and serpentine Egyptian ores. A collimated beam obtained from an Am-Be source was used as a source of neutrons, while the measurements of total thermal, epithermal, and thermalized neutron fluxes were performed using a BF-3 detector, multichannel analyzer and Cd filter. Results show that the ilmenite-serpentine concrete proved to be a better thermal, epithermal and thermalized neutron attenuator than the ordinary concrete especially at a high temperature of concrete exposure.

  13. On the collective appearance of coronal loops and the resistive heating instability

    NASA Astrophysics Data System (ADS)

    Lou, Yu-Qing

    We investigate the onset conditions for direct resistive heating instabilities coupled with radiative processes within a twisted magnetic flux rope of axisymmetry and relate the helical patterns wrapping along the rope initiated by such instabilities to the collective appearance of compact X-ray loops in a certain phase of active region development in the solar corona. Since the emergence and the subsequent evolution of a gigantic magnetic flux rope in the solar atmosphere involve complicated physical processes, it is expected that such instabilities occurring in an ensemble of many current sheaths embedded in a stressed, twisted, and bulged magnetic flux rope will manifest as collective X-ray loop structures on various spatial scales and with varieties of large-scale morphologies.

  14. Improvement of corrosion resistance of Nisbnd Mo alloy coatings: Effect of heat treatment

    NASA Astrophysics Data System (ADS)

    Mousavi, R.; Bahrololoom, M. E.; Deflorian, F.; Ecco, L.

    2016-02-01

    In this paper, Nisbnd Mo alloy coatings were deposited from bath containing sodium citrate, nickel sulphate, and sodium molybdate. Essentially, this work is divided into two mains parts: (i) the optimization on the coatings deposition parameters and (ii) the effect of the heat treatment. Polarization curves and electrochemical impedance spectroscopy were acquired using potentiostat/galvanostat and a frequency response analyzer, respectively. Morphology and chemical composition of the coatings were investigated by scanning electron microscopy and energy dispersive spectroscopy, respectively. Polarization curves at different condition revealed that electroplating at temperature 40 oC, pH 9 provides a dense coating with high efficiency. Following the optimization of the deposition parameters, the coatings were annealed at 200, 400, and 600 oC for 25 min. The results showed that the coatings obtained at temperature 40 oC, pH 9, and annealing at 600 oC has the highest corrosion resistance and microhardness.

  15. Fire- and heat-resistant laminating resins based on maleimido-substituted aromatic cyclotriphosphazenes

    NASA Technical Reports Server (NTRS)

    Kumar, D.; Fohlen, G. M.; Parker, J. A.

    1983-01-01

    A novel class of flame- and heat-resistant polymers has been synthesized by the thermal polymerization of maleimido-substituted aromatic cyclotriphosphazenes. The polymer obtained from tris-(aminophenoxy)tris(maleimidophenoxy)cyclotriphosphazene has good thermal stability and is noteworthy for its high char yield, viz., 82 percent at 800 C in nitrogen and 81 percent at 700 C in air. Graphite-fabric laminates prepared with this polymer did not burn in pure oxygen, even at 300 C, and were tested for mechanical properties. Hexakis(4-maleimidophenoxy)cyclotriphosphazene and some fluorine-containing monomers have also been synthesized. The structures of these cyclic phosphazene precursors and polymers were characterized by FT IR spectrophotometry, H-1 NMR, F-19 NMR, and P-31 solid-state magic angle spinning NMR spectroscopy, and mass spectrometry. The curing behavior of the polymer precursors and the thermal stabilities of the polymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA).

  16. Scorpion Venom Heat-Resistant Peptide Protects Transgenic Caenorhabditis elegans from β-Amyloid Toxicity

    PubMed Central

    Zhang, Xiao-Gang; Wang, Xi; Zhou, Ting-Ting; Wu, Xue-Fei; Peng, Yan; Zhang, Wan-Qin; Li, Shao; Zhao, Jie

    2016-01-01

    Scorpion venom heat-resistant peptide (SVHRP) is a component purified from Buthus martensii Karsch scorpion venom. Our previous studies found SVHRP could enhance neurogenesis and inhibit microglia-mediated neuroinflammation in vivo. Here, we use the transgenic CL4176, CL2006, and CL2355 strains of Caenorhabditis elegans which express the human Aβ1-42 to investigate the effects and the possible mechanisms of SVHRP mediated protection against Aβ toxicity in vivo. The results showed that SVHRP-fed worms displayed remarkably decreased paralysis, less abundant toxic Aβ oligomers, reduced Aβ plaque deposition with respect to untreated animals. SVHRP also suppressed neuronal Aβ expression-induced defects in chemotaxis behavior and attenuated levels of ROS in the transgenic C. elegans. Taken together, these results suggest SVHRP could protect against Aβ-induced toxicity in C. elegans. Further studies need to be conducted in murine models and humans to analyze the effectiveness of the peptide. PMID:27507947

  17. Simple evaporation controller for thin-film deposition from a resistively heated boat

    NASA Astrophysics Data System (ADS)

    Scofield, John H.; Bajuk, Lou; Mohler, William

    1990-07-01

    A simple, inexpensive circuit is described for switching the current through a resistively heated evaporation boat during thin-film deposition. The circuit uses a silicon-controlled rectifier (SCR) to switch the 0-15-A current in the primary of a 2-kV A step-down transformer that supplies the 0-200-A current to an evaporation boat. The circuit is controlled by a 0-10 V-dc signal similar to that furnished by an Inficon XTC deposition-rate controller. This circuit may be assembled from a handful of parts for a cost of about $400, nearly one-tenth the cost of similar commercial units. Minimum construction is required, since the circuit is built around an off-the-shelf, self-contained SCR unit.

  18. Simple evaporation controller for thin-film deposition from a resistively heated boat

    NASA Technical Reports Server (NTRS)

    Scofield, John H.; Bajuk, Lou; Mohler, William

    1990-01-01

    A simple, inexpensive circuit is described for switching the current through a resistively heated evaporation boat during thin-film deposition. The circuit uses a silicon-controlled rectifier (SCR) to switch the 0-15-A current in the primary of a 2-kV A step-down transformer that supplies the 0-200-A current to an evaporation boat. The circuit is controlled by a 0-10 V-dc signal similar to that furnished by an Inficon XTC deposition-rate controller. This circuit may be assembled from a handful of parts for a cost of about $400, nearly one-tenth the cost of similar commercial units. Minimum construction is required, since the circuit is built around an off-the-shelf, self-contained SCR unit.

  19. Heat, Moisture and Chemical Resistant Polyimide Compositions and Methods for Making and Using Them

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    2004-01-01

    Polyimides having a desired combination of high thermo-oxidative stability, low moisture absorption and excellent chemical and corrosion resistance are prepared by reacting a mixture of compounds including (a) 3,3',4,4'- benzophenonetetracarboxylic dianhydride (BTDA), (b) 3,4'- oxydianiline (3,4'-ODA), and (c) 5-norbornene-2,3- dicarboxylic anhydride (NA) in a high boiling, aprotic solvent to give 5 to 35% by weight of polyamic acid solution. The ratio of (a), (b), and (c) is selected to afford a family of polyimides having different molecular weights and properties. The mixture first forms a polyamic acid precursor. Upon heating at or above 300 C, the polyamic acids form polyimides, which are particularly suitable for use as a high temperature coating, adhesive, thin film, or composite matrix resin.

  20. Scorpion Venom Heat-Resistant Peptide Protects Transgenic Caenorhabditis elegans from β-Amyloid Toxicity.

    PubMed

    Zhang, Xiao-Gang; Wang, Xi; Zhou, Ting-Ting; Wu, Xue-Fei; Peng, Yan; Zhang, Wan-Qin; Li, Shao; Zhao, Jie

    2016-01-01

    Scorpion venom heat-resistant peptide (SVHRP) is a component purified from Buthus martensii Karsch scorpion venom. Our previous studies found SVHRP could enhance neurogenesis and inhibit microglia-mediated neuroinflammation in vivo. Here, we use the transgenic CL4176, CL2006, and CL2355 strains of Caenorhabditis elegans which express the human Aβ1-42 to investigate the effects and the possible mechanisms of SVHRP mediated protection against Aβ toxicity in vivo. The results showed that SVHRP-fed worms displayed remarkably decreased paralysis, less abundant toxic Aβ oligomers, reduced Aβ plaque deposition with respect to untreated animals. SVHRP also suppressed neuronal Aβ expression-induced defects in chemotaxis behavior and attenuated levels of ROS in the transgenic C. elegans. Taken together, these results suggest SVHRP could protect against Aβ-induced toxicity in C. elegans. Further studies need to be conducted in murine models and humans to analyze the effectiveness of the peptide. PMID:27507947

  1. Effect of sporulation conditions on the resistance of Bacillus subtilis spores to heat and high pressure.

    PubMed

    Nguyen Thi Minh, Hue; Durand, Alain; Loison, Pauline; Perrier-Cornet, Jean-Marie; Gervais, Patrick

    2011-05-01

    Bacillus subtilis(B. subtilis) cells were placed in various environmental conditions to study the effects of aeration, water activity of the medium, temperature, pH, and calcium content on spore formation and the resulting properties. Modification of the sporulation conditions lengthened the growth period of B. subtilis and its sporulation. In some cases, it reduced the final spore concentration. The sporulation conditions significantly affected the spore properties, including germination capacity and resistance to heat treatment in water (30 min at 97°C) or to high pressure (60 min at 350 MPa and 40°C). The relationship between the modifications of these spore properties and the change in the spore structure induced by different sporulation conditions is also considered. According to this study, sporulation conditions must be carefully taken into account during settling sterilization processes applied in the food industry. PMID:21380515

  2. Development of Cast Alumina-forming Austenitic Stainless Steel Alloys for use in High Temperature Process Environments

    SciTech Connect

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P; Pint, Bruce A; Pankiw, Roman; Voke, Don

    2015-01-01

    There is significant interest in the development of alumina-forming, creep resistant alloys for use in various industrial process environments. It is expected that these alloys can be fabricated into components for use in these environments through centrifugal casting and welding. Based on the successful earlier studies on the development of wrought versions of Alumina-Forming Austenitic (AFA) alloys, new alloy compositions have been developed for cast products. These alloys achieve good high-temperature oxidation resistance due to the formation of protective Al2O3 scales while multiple second-phase precipitation strengthening contributes to excellent creep resistance. This work will summarize the results on the development and properties of a centrifugally cast AFA alloy. This paper highlights the strength, oxidation resistance in air and water vapor containing environments, and creep properties in the as-cast condition over the temperature range of 750°C to 900°C in a centrifugally cast heat. Preliminary results for a laboratory cast AFA composition with good oxidation resistance at 1100°C are also presented.

  3. Calculation and experimental study on high-speed impact of heat-resistant coating materials with a meteoric particle

    NASA Astrophysics Data System (ADS)

    Glazunov, Anatoly; Ishchenko, Aleksandr; Afanas'eva, Svetlana; Belov, Nikolai; Burkin, Viktor; Rogaev, Konstantin; Yugov, Nikolai

    2016-01-01

    The given article presents the conducted calculation and experimental study on destruction of heat-resistant coating material of an aircraft in the process of high-speed interaction of the steel spherical projectile. The projectile is imitating a meteoric particle. The study was conducted in the wide range of velocities. The mathematical behavioral model of heat-resistant coating under high-speed impact was developed. The interaction of ameteoric particle with an element of the protective structure has especially individual character and depends on impact velocity and angle, materials of the interacting solids.

  4. Evaluation of an EMITEC resistively heated metal monolith catalytic converter on two M100 neat methanol-fueled vehicles

    NASA Astrophysics Data System (ADS)

    Piotrowski, Gregory K.; Schaefer, Ronald M.

    1992-12-01

    The report describes the evaluation of a resistively heated catalyst system on two different methanol fueled vehicles. The EMITEC catalyst consisted of a compact resistively heated metal monolith in front of a larger conventional main converter. The EMITEC catalyst was evaluated on two neat methanol-fueled vehicles, a 1981 Volkswagen Rabbit and a 1988 Toyota Corolla. Emission testing was conducted over the Federal Test Procedure (FTP) CVS-75 test cycle. The emissions of primary interest were cold start methanol (unburned fuel), carbon monoxide, and formaldehyde.

  5. Abrasion Resistance of as-Cast High-Chromium Cast Iron

    NASA Astrophysics Data System (ADS)

    Pokusová, Marcela; Berta, Igor; Šooš, Ľubomír

    2014-12-01

    High chromium cast irons are widely used as abrasion resistant materials. Their properties and wear resistance depend on carbides and on the nature of the matrix supporting these carbides. The paper presents test results of irons which contain (in wt.%) 18-22 Cr and 2-5 C, and is alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve the toughness. Tests showed as-cast irons with mostly austenitic matrix achieved hardness 36-53 HRC but their relative abrasion-resistance was higher than the tool steel STN 19436 heat treated on hardness 60 HRC.

  6. The SpmA/B and DacF proteins of Clostridium perfringens play important roles in spore heat resistance.

    PubMed

    Orsburn, Benjamin; Sucre, Katie; Popham, David L; Melville, Stephen B

    2009-02-01

    Strains of Clostridium perfringens that cause acute food poisoning have been shown to produce spores that are significantly more heat resistant than those of other strains. Previous studies demonstrated that the spore core density and the ratio of spore cortex peptidoglycan relative to the germ cell wall were factors that correlated with the heat resistance of a C. perfringens spore. To further evaluate these relationships, mutant strains of C. perfringens SM101 were constructed with null mutations in dacF, encoding a D,D-carboxypeptidase, and in the spmA-spmB operon, which is involved in spore core dehydration. The dacF mutant was shown to produce less spore cortex peptidoglycan and had a corresponding decrease in spore heat resistance. The spmA-spmB strain produced highly unstable spores with significantly lower core densities and increased heat sensitivity, which were easily destroyed during treatments affecting the spore coat layers. These results support the previous assertion that a threshold core density as well as a high ratio of cortex peptidoglycan relative to the germ cell wall contribute to the formation of a more heat-resistant spore in this species. PMID:19189487

  7. HTFLO: a computer model of a resistively-heated UO/sub 2/ pin with a rate-dependent heat capacity. [LMFBR

    SciTech Connect

    Smaardyk, J.E.

    1980-02-01

    A one-dimensional model is presented to describe the thermal behavior of an uranium dioxide (UO/sub 2/) rod that is heated resistively and cooled by surface radiation. A standard forward differencing scheme is used for the heat transfer calculations. Temperature-dependent electrical and thermal properties are calculated at the beginning of each time step. In addition, the heat capacity is calculated from a dynamic enthalpy model based on equilibrium and instantaneous heat capacity models with a user-selectable relaxation time. This report describes the finite difference equations used, the treatment of the source and boundary terms, and the dynamic enthalpy model. Detailed input instructions are provided and a sample calculation is shown.

  8. Multilocus adaptation associated with heat resistance in reef-building corals.

    PubMed

    Bay, Rachael A; Palumbi, Stephen R

    2014-12-15

    The evolution of tolerance to future climate change depends on the standing stock of genetic variation for resistance to climate-related impacts, but genes contributing to climate tolerance in wild populations are poorly described in number and effect. Physiology and gene expression patterns have shown that corals living in naturally high-temperature microclimates are more resistant to bleaching because of both acclimation and fixed effects, including adaptation. To search for potential genetic correlates of these fixed effects, we genotyped 15,399 single nucleotide polymorphisms (SNPs) in 23 individual tabletop corals, Acropora hyacinthus, within a natural temperature mosaic in backreef lagoons on Ofu Island, American Samoa. Despite overall lack of population substructure, we identified 114 highly divergent SNPs as candidates for environmental selection, via multiple stringent outlier tests, and correlations with temperature. Corals from the warmest reef location had higher minor allele frequencies across these candidate SNPs, a pattern not seen for noncandidate loci. Furthermore, within backreef pools, colonies in the warmest microclimates had a higher number and frequency of alternative alleles at candidate loci. These data suggest mild selection for alternate alleles at many loci in these corals during high heat episodes and possible maintenance of extensive polymorphism through multilocus balancing selection in a heterogeneous environment. In this case, a natural population harbors a reservoir of alleles preadapted to high temperatures, suggesting potential for future evolutionary response to climate change. PMID:25454780

  9. High-temperature experiments using a resistively heated high-pressure membrane diamond anvil cell.

    PubMed

    Jenei, Zsolt; Cynn, Hyunchae; Visbeck, Ken; Evans, William J

    2013-09-01

    We describe a reliable high performance resistive heating method developed for the membrane diamond anvil cell. This method generates homogenous high temperatures at high pressure in the whole sample for extended operation period. It relies on two mini coil heaters made of Pt-Rh alloy wire mounted around the diamond anvils and gasket, while temperature is monitored by two K-type thermocouples mounted near the sample. The sample, diamonds, and tungsten-carbide seats are thermally insulated from the piston and cylinder keeping the cell temperature below 750 K while the sample temperature is 1200 K. The cell with the heaters is placed in a vacuum oven to prevent oxidation and unnecessary heat loss. This assembly allows complete remote operation, ideally suited for experiments at synchrotron facilities. Capabilities of the setup are demonstrated for in situ Raman and synchrotron x-ray diffraction measurements. We show experimental measurements from isothermal compression at 900 K and 580 K to 100 GPa and 185 GPa, respectively, and quasi-isobaric compression at 95 GPa over 1000 K. PMID:24089873

  10. Emerging Role of Nitric Oxide and Heat Shock Proteins in Insulin Resistance.

    PubMed

    Molina, Marisa Nile; Ferder, León; Manucha, Walter

    2016-01-01

    Insulin resistance (IR) is present in pathologies such as diabetes, obesity, metabolic syndrome, impaired glucose tolerance, hypertension, inflammation, cardiac disease, and dyslipidemias. Population studies show that IR is multifactorial and has genetic components, such as defects in the insulin-signaling pathway (as serine phosphorylation on insulin substrate or decreased activation of signaling molecules) and RAS/MAPK-dependent pathways. IR is connected to mitochondrial dysfunction, overproduction of oxidants, accumulation of fat, and an over-activation of the renin-angiotensin system linked to the NADPH oxidase activity. In addition, nitric oxide (NO), synthesized by nitric oxide synthases (endothelial and inducible), is also associated with IR when both impaired release and reduced bioavailability of all which lead to inflammation and hypertension. However, increased NO may promote vasculoprotection. Moreover, reduced NO release induces heat shock protein 70 kDa (HSP70) expression in IR and diabetes, mediating beneficial effects against oxidative stress injury, inflammation and apoptosis. HSP70 may be used as biomarker of the chronicity of diabetes. Hsp72 (inducible protein) is linked to vascular complications with a high-fat diet by blocking inflammation signaling (cytoprotective and anti-cytotoxicity intracellular role). Elucidating the IR signaling pathways and the roles of NO and HSPs is relevant to the application of new treatments, such as heat shock and thermal therapy, nitrosylated drugs, chemical chaperones or exercise training. PMID:26694820

  11. Manufacture of a heat-resistant alloy with modified specifications for HTGR structural applications

    SciTech Connect

    Sahira, K.; Kondo, T.; Takeiri, T.

    1984-07-01

    A method of manufacturing a nuclear grade nickel-base heat-resistant alloy in application to heliumcooled reactor primary circuit components has been developed. The Hastelloy-XR alloy, a version of Hastelloy-X, was made available by combining the basic studies of the oxidation behavior of Hastelloy-X and the improvement of manufacturing techniques. In the primary and remelting steps, the choice of appropriate processes was made by performing numerical analyses of the statistical deviation of both chemical composition and the products' mechanical properties. The feasibility of making larger electroslag remelting ingots with reasonable control of macrosegregation was examined by the calculation of a molten metal pool shape during melting. The hot workability of Hastelloy-XR was confirmed to be equivalent to that of Hastelloy-X and the importance of controlling the thermal and mechanical processes more closely was stressed in obtaining a higher level of quality assurance for the nuclear applications. The possibility of enhancing the high-temperature mechanical performance of Hastelloy-XR was suggested based on the preliminary test results with the heats manufactured with controlled boron content.

  12. Characterization and radiation response of a heat-resistant variant of V79 cells

    SciTech Connect

    Campbell, S.D.; Kruuv, J.; Lepock, J.R.

    1983-01-01

    A thermoresistant variant of the established cell line V79-S171-W1 was isolated after treatment with nitrosoguanidine and repeated heat treatments at 42.6 to 43 degrees C, and showed an enhanced ability to survive at 42.6, 43.5, and 44.5 degrees C. The rates of inactivation of the normal and heat-resistant lines differed by approximately a factor of 2 over this temperature range. This level of thermoresistance was stable for the first 80 doublings, but was lost by 120 doublings. This may have been due to a reversion to the normal V79 line since there was no continuous selection pressure and the thermoresistant variant, which was designated at HR7, had a longer average doubling time. Transient thermotolerance was induced in both the V79 and HR7 cells by a 10-min exposure to 44.5 degrees C. After 3 hr incubation at 37 degrees C, both cell lines had an identical sensitivity to further exposure to 44.5 degrees C. Thus the long-term thermoresistance of the HR7 cells may be due to a permanent induction of a low level of thermotolerance. The (ionizing) radiation survival curves and the ability to repair sublethal radiation damage were identical for the thermoresistant variant and the parent cell line.

  13. Design of a Resistively Heated Thermal Hydraulic Simulator for Nuclear Rocket Reactor Cores

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.; Foote, John P.; Ramachandran, Narayanan; Wang, Ten-See; Anghaie, Samim

    2007-01-01

    A preliminary design study is presented for a non-nuclear test facility which uses ohmic heating to replicate the thermal hydraulic characteristics of solid core nuclear reactor fuel element passages. The basis for this testing capability is a recently commissioned nuclear thermal rocket environments simulator, which uses a high-power, multi-gas, wall-stabilized constricted arc-heater to produce high-temperature pressurized hydrogen flows representative of reactor core environments, excepting radiation effects. Initially, the baseline test fixture for this non-nuclear environments simulator was configured for long duration hot hydrogen exposure of small cylindrical material specimens as a low cost means of evaluating material compatibility. It became evident, however, that additional functionality enhancements were needed to permit a critical examination of thermal hydraulic effects in fuel element passages. Thus, a design configuration was conceived whereby a short tubular material specimen, representing a fuel element passage segment, is surrounded by a backside resistive tungsten heater element and mounted within a self-contained module that inserts directly into the baseline test fixture assembly. With this configuration, it becomes possible to create an inward directed radial thermal gradient within the tubular material specimen such that the wall-to-gas heat flux characteristics of a typical fuel element passage are effectively simulated. The results of a preliminary engineering study for this innovative concept are fully summarized, including high-fidelity multi-physics thermal hydraulic simulations and detailed design features.

  14. Retained austenite thermal stability in a nanostructured bainitic steel

    SciTech Connect

    Avishan, Behzad; Garcia-Mateo, Carlos; Yazdani, Sasan; Caballero, Francisca G.

    2013-07-15

    The unique microstructure of nanostructured bainite consists of very slender bainitic ferrite plates and high carbon retained austenite films. As a consequence, the reported properties are opening a wide range of different commercial uses. However, bainitic transformation follows the T{sub 0} criteria, i.e. the incomplete reaction phenomena, which means that the microstructure is not thermodynamically stable because the bainitic transformation stops well before austenite reaches an equilibrium carbon level. This article aims to study the different microstructural changes taking place when nanostructured bainite is destabilized by austempering for times well in excess of that strictly necessary to end the transformation. Results indicate that while bainitic ferrite seems unaware of the extended heat treatment, retained austenite exhibits a more receptive behavior to it. - Highlights: • Nanostructured bainitic steel is not thermodynamically stable. • Extensive austempering in these microstructures has not been reported before. • Precipitation of cementite particles is unavoidable at longer austempering times. • TEM, FEG-SEM and XRD analysis were used for microstructural characterization.

  15. Efficacy of Traditional Almond Decontamination Treatments and Electron Beam Irradiation against Heat-Resistant Salmonella Strains.

    PubMed

    Cuervo, Mary P; Lucia, Lisa M; Castillo, Alejandro

    2016-03-01

    Two outbreaks of salmonellosis were linked to the consumption of raw almonds from California in 2001 and 2004. As a result, federal regulations were developed, which mandate that all almonds grown in California must be treated with a process that results in a 4-log reduction of Salmonella. Because most of the technologies approved to treat almonds rely on the application of heat to control Salmonella, an evaluation of alternative technologies for inactivating heat-resistant Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W was needed. In this study, almonds were inoculated with Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W and then treated with an electron beam (e-beam) or by blanching or oil roasting. The irradiation D10-values for Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W treated with e-beam were 0.90 and 0.72 kGy, respectively. For heat treatments, thermal D10-values for Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W strains were 15.6 and 12.4 s, respectively, when subjected to blanching at 88°C and 13.2 and 10.9 s, respectively, when roasted in oil at 127 ± 2°C. No significant differences in irradiation and thermal treatment results were observed between Salmonella Enteritidis PT30 and Salmonella Senftenberg 775W (P > 0.05), indicating that e-beam irradiation may be a feasible technology for reducing Salmonella in almonds. However, the sensory changes resulting from irradiating at the doses used in this study must be evaluated before e-beam irradiation can be used as a nonthermal alternative for decontamination of almonds. PMID:26939646

  16. Gas production and transport during bench-scale electrical resistance heating of water and trichloroethene

    NASA Astrophysics Data System (ADS)

    Hegele, P. R.; Mumford, K. G.

    2014-09-01

    The effective remediation of chlorinated solvent source zones using in situ thermal treatment requires successful capture of gas that is produced. Replicate electrical resistance heating experiments were performed in a thin bench-scale apparatus, where water was boiled and pooled dense non-aqueous phase liquid (DNAPL) trichloroethene (TCE) and water were co-boiled in unconsolidated silica sand. Quantitative light transmission visualization was used to assess gas production and transport mechanisms. In the water boiling experiments, nucleation, growth and coalescence of the gas phase into connected channels were observed at critical gas saturations of Sgc = 0.233 ± 0.017, which allowed for continuous gas transport out of the sand. In experiments containing a colder region above a target heated zone, condensation prevented the formation of steam channels and discrete gas clusters that mobilized into colder regions were trapped soon after discontinuous transport began. In the TCE-water experiments, co-boiling at immiscible fluid interfaces resulted in discontinuous gas transport above the DNAPL pool. Redistribution of DNAPL was also observed above the pool and at the edge of the vapor front that propagated upwards through colder regions. These results suggest that the subsurface should be heated to water boiling temperatures to facilitate gas transport from specific locations of DNAPL to extraction points and reduce the potential for DNAPL redistribution. Decreases in electric current were observed at the onset of gas phase production, which suggests that coupled electrical current and temperature measurements may provide a reliable metric to assess gas phase development.

  17. A review on nickel-free nitrogen containing austenitic stainless steels for biomedical applications.

    PubMed

    Talha, Mohd; Behera, C K; Sinha, O P

    2013-10-01

    The field of biomaterials has become a vital area, as these materials can enhance the quality and longevity of human life. Metallic materials are often used as biomaterials to replace structural components of the human body. Stainless steels, cobalt-chromium alloys, commercially pure titanium and its alloys are typical metallic biomaterials that are being used for implant devices. Stainless steels have been widely used as biomaterials because of their very low cost as compared to other metallic materials, good mechanical and corrosion resistant properties and adequate biocompatibility. However, the adverse effects of nickel ions being released into the human body have promoted the development of "nickel-free nitrogen containing austenitic stainless steels" for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also much improves steel properties. Here we review the harmful effects associated with nickel and emphatically the advantages of nitrogen in stainless steel, as well as the development of nickel-free nitrogen containing stainless steels for medical applications. By combining the benefits of stable austenitic structure, high strength, better corrosion and wear resistance and superior biocompatibility in comparison to the currently used austenitic stainless steel (e.g. 316L), the newly developed nickel-free high nitrogen austenitic stainless steel is a reliable substitute for the conventionally used medical stainless steels. PMID:23910251

  18. Heat and corrosion resistant cast CN-12 type stainless steel with improved high temperature strength and ductility

    DOEpatents

    Mazias, Philip J.; McGreevy, Tim; Pollard,Michael James; Siebenaler, Chad W.; Swindeman, Robert W.

    2007-08-14

    A cast stainless steel alloy and articles formed therefrom containing about 0.5 wt. % to about 10 wt. % manganese, 0.02 wt. % to 0.50 wt. % N, and less than 0.15 wt. % sulfur provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. Alloys of the present invention also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon. Such solution strengthening enhances the high temperature precipitation-strengthening benefits of fine dispersions of NbC. Such solid solution effects also enhance the stability of the austenite matrix from resistance to excess sigma phase or chrome carbide formation at higher service temperatures. The presence of sulfides is substantially eliminated.

  19. Wrought stainless steel compositions having engineered microstructures for improved heat resistance

    DOEpatents

    Maziasz, Philip J [Oak Ridge, TN; Swindeman, Robert W [Oak Ridge, TN; Pint, Bruce A [Knoxville, TN; Santella, Michael L [Knoxville, TN; More, Karren L [Knoxville, TN

    2007-08-21

    A wrought stainless steel alloy composition includes 12% to 25% Cr, 8% to 25% Ni, 0.05% to 1% Nb, 0.05% to 10% Mn, 0.02% to 0.15% C, 0.02% to 0.5% N, with the balance iron, the composition having the capability of developing an engineered microstructure at a temperature above 550.degree. C. The engineered microstructure includes an austenite matrix having therein a dispersion of intragranular NbC precipitates in a concentration in the range of 10.sup.10 to 10.sup.17 precipitates per cm.sup.3.

  20. The Heat Resistance of Microbial Cells Represented by D Values Can be Estimated by the Transition Temperature and the Coefficient of Linear Expansion.

    PubMed

    Nakanishi, Koichi; Kogure, Akinori; Deuchi, Keiji; Kuwana, Ritsuko; Takamatsu, Hiromu; Ito, Kiyoshi

    2015-01-01

    We previously developed a method for evaluating the heat resistance of microorganisms by measuring the transition temperature at which the coefficient of linear expansion of a cell changes. Here, we performed heat resistance measurements using a scanning probe microscope with a nano thermal analysis system. The microorganisms studied included six strains of the genus Bacillus or related genera, one strain each of the thermophilic obligate anaerobic bacterial genera Thermoanaerobacter and Moorella, two strains of heat-resistant mold, two strains of non-sporulating bacteria, and one strain of yeast. Both vegetative cells and spores were evaluated. The transition temperature at which the coefficient of linear expansion due to heating changed from a positive value to a negative value correlated strongly with the heat resistance of the microorganism as estimated from the D value. The microorganisms with greater heat resistance exhibited higher transition temperatures. There was also a strong negative correlation between the coefficient of linear expansion and heat resistance in bacteria and yeast, such that microorganisms with greater heat resistance showed lower coefficients of linear expansion. These findings suggest that our method could be useful for evaluating the heat resistance of microorganisms. PMID:26699861

  1. High Mn austenitic stainless steel

    DOEpatents

    Yamamoto, Yukinori [Oak Ridge, TN; Santella, Michael L [Knoxville, TN; Brady, Michael P [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Liu, Chain-tsuan [Knoxville, TN

    2010-07-13

    An austenitic stainless steel alloy includes, in weight percent: >4 to 15 Mn; 8 to 15 Ni; 14 to 16 Cr; 2.4 to 3 Al; 0.4 to 1 total of at least one of Nb and Ta; 0.05 to 0.2 C; 0.01 to 0.02 B; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1W; up to 3 Cu; up to 1 Si; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale including alumina, nanometer scale sized particles distributed throughout the microstructure, the particles including at least one of NbC and TaC, and a stable essentially single phase FCC austenitic matrix microstructure that is essentially delta-ferrite-free and essentially BCC-phase-free.

  2. Investigation of thermal spray coatings on austenitic stainless steel substrate to enhance corrosion protection

    NASA Astrophysics Data System (ADS)

    Rogers, Daniel M.

    The research is aimed to evaluate thermal spray coatings to address material issues in supercritical and ultra-supercritical Rankine cycles. The primary purpose of the research is to test, evaluate, and eventually implement a coating to improve corrosion resistance and increase efficiency of coal fired power plants. The research is performed as part of a comprehensive project to evaluate the ability of titanium, titanium carbide, or titanium diboride powders to provide fireside corrosion resistance in supercritical and ultra-supercritical steam boilers, specifically, coal driven boilers in Illinois that must utilize high sulfur and high chlorine content coal. [1] The powder coatings that were tested are nano-sized titanium carbide (TiC) and titanium di-boride (TiB2) powders that were synthesized by a patented process at Southern Illinois University. The powders were then sent to Gas Technology Institute in Chicago to coat steel coupons by HVOF (High Velocity Oxy-Fuel) thermal spray technique. The powders were coated on an austenitic 304H stainless steel substrate which is commonly found in high temperature boilers, pipelines, and heat exchangers. The samples then went through various tests for various lengths of time under subcritical, supercritical, and ultra-supercritical conditions. The samples were examined using a scanning electron microscope and x-ray diffraction techniques to study microstructural changes and then determined which coating performed best.

  3. Austenitic stainless steels and high strength copper alloys for fusion components

    NASA Astrophysics Data System (ADS)

    Rowcliffe, A. F.; Zinkle, S. J.; Stubbins, J. F.; Edwards, D. J.; Alexander, D. J.

    1998-10-01

    An austenitic stainless steel (316LN), an oxide-dispersion-strengthened copper alloy (GlidCop Al25), and a precipitation-hardened copper alloy (Cu-Cr-Zr) are the primary structural materials for the ITER first wall/blanket and divertor systems. While there is a long experience of operating 316LN stainless steel in nuclear environments, there is no prior experience with the copper alloys in neutron environments. The ITER first wall (FW) consists of a stainless steel shield with a copper alloy heat sink bonded by hot isostatic pressing (HIP). The introduction of bi-layer structural material represents a new materials engineering challenge; the behavior of the bi-layer is determined by the properties of the individual components and by the nature of the bond interface. The development of the radiation damage microstructure in both classes of materials is summarized and the effects of radiation on deformation and fracture behavior are considered. The initial data on the mechanical testing of bi-layers indicate that the effectiveness of GlidCop Al25 as a FW heat sink material is compromised by its strongly anisotropic fracture toughness and poor resistance to crack growth in a direction parallel to the bi-layer interface.

  4. Physiological quality and gene expression related to heat-resistant proteins at different stages of development of maize seeds.

    PubMed

    Andrade, T; Von Pinho, E V R; Von Pinho, R G; Oliveira, G E; Andrade, V; Fernandes, J S

    2013-01-01

    We quantified and characterized the expression of heat-resistant proteins during seed development of maize lines with distinct levels of tolerance to high drying temperature. A corn field was planted for multiplication of seeds of different lines, two tolerant and two non-tolerant to high drying temperatures. Harvest of the seeds was carried out at various stages of development and they were then subjected to tests of moisture content, germination, first count of germination, accelerated aging, and cold test. The seeds were stored in a freezer for later analysis of expression of heat-resistant proteins by means of real-time PCR, electrophoresis, and spectrophotometry. We observed that heat-resistant proteins are expressed in a differential manner in seeds from different lines and at different stages of development. The expression of heat-resistant proteins was earlier in lines tolerant to high drying temperatures. Greater germination and vigor values was found for seeds collected at the last stage of development. PMID:24085427

  5. Effect of rotation on heat transfer and hydraulic resistance in the radial cooling channels of turbine rotor blades

    NASA Astrophysics Data System (ADS)

    Iskakov, K. M.; Trushin, O. V.; Tsaplin, M. I.; Shatalov, Yu. S.

    Results of a modeling study indicate that rotation significantly (up to 60 percent) changes local heat transfer and increases, by a factor of 5-6, hydraulic resistance in the smooth radial channels of turbine rotor blades with a low-pressure cooling system. The results of the study have been used in the design of a turbine cooling system for a turbofan engine.

  6. Dry heat or gaseous chemical resistance of Bacillus subtilis var. niger spores included within water-soluble crystals.

    PubMed

    Mullican, C L; Hoffman, R K

    1968-08-01

    Inclusion of spores of Bacillus subtilis var. niger in water-soluble crystals increased the resistance of the spores to dry heat and to a gaseous mixture of methyl bromide and ethylene oxide. Resistance of spores in glycine crystals to dry heat at 125 C was increased 5 to 24 times compared to unprotected spores. There appeared to be a positive correlation between the size of the crystal and the degree of resistance. The resistance to dry heat of spores included in sodium chloride crystals was about six times greater than unprotected spores. A gaseous mixture of methyl bromide (964 mg/liter) and ethylene oxide (642 mg/liter) at 37% relative humidity was ineffective in sterilizing spores enclosed within these water-soluble crystals, as was ethylene oxide alone. However, if the relative humidity was sufficiently high to dissolve the crystals during exposure to the vapor, viable-spore counts were drastically reduced or were negative. The surfaces of crystals grossly contaminated with dry spores were sterilized by exposure to gaseous ethylene oxide. Sterilization of heat-labile or moisture-labile materials with a critical requirement for sterility, as in planetary probes or drugs, may be complicated by the presence of spores in naturally occurring water-soluble crystals. This phenomenon is similar to the protection afforded spores entrapped in solid plastics. PMID:4970891

  7. Mi-1-mediated nematode resistance in tomatoes is broken by short-term heat stress but recovers over time

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In tomato (Solanum lycopersicum Mill.), the only available genomic resource of resistance to root-knot nematodes (RKN; Meloidogyne incognita, M. javanica and M. arenaria), which are considered among the most devastating crop pests worldwide, is a single dominant gene termed Mi-1. Heat stress is thou...

  8. Dry Heat or Gaseous Chemical Resistance of Bacillus subtilis var. niger Spores Included Within Water-soluble Crystals

    PubMed Central

    Mullican, Charles L.; Hoffman, Robert K.

    1968-01-01

    Inclusion of spores of Bacillus subtilis var. niger in water-soluble crystals increased the resistance of the spores to dry heat and to a gaseous mixture of methyl bromide and ethylene oxide. Resistance of spores in glycine crystals to dry heat at 125 C was increased 5 to 24 times compared to unprotected spores. There appeared to be a positive correlation between the size of the crystal and the degree of resistance. The resistance to dry heat of spores included in sodium chloride crystals was about six times greater than unprotected spores. A gaseous mixture of methyl bromide (964 mg/liter) and ethylene oxide (642 mg/liter) at 37% relative humidity was ineffective in sterilizing spores enclosed within these water-soluble crystals, as was ethylene oxide alone. However, if the relative humidity was sufficiently high to dissolve the crystals during exposure to the vapor, viable-spore counts were drastically reduced or were negative. The surfaces of crystals grossly contaminated with dry spores were sterilized by exposure to gaseous ethylene oxide. Sterilization of heat-labile or moisture-labile materials with a critical requirement for sterility, as in planetary probes or drugs, may be complicated by the presence of spores in naturally occurring water-soluble crystals. This phenomenon is similar to the protection afforded spores entrapped in solid plastics. PMID:4970891

  9. Farmers' perceptions and knowledge of cattle adaptation to heat stress and tick resistance in the eastern cape, South Africa.

    PubMed

    Katiyatiya, C L F; Muchenje, V; Mushunje, A

    2014-11-01

    The objective of this study was to determine the perceptions and knowledge of farmers of heat stress and tick resistance in cattle. A cross-sectional survey was conducted and 110 farmers in four villages in the sour and sweet velds of the Eastern Cape Province, South Africa were interviewed. The associations among area (municipality), gender, age, level of education, employment and religion were computed using Chi-square tests. The majority of the respondents had on average 4 bulls, 4 cows, 4 heifers, 4 calves, and 4 oxen. Milk was considered as the major (28.3%) reason for keeping cattle. Most farmers owned non-descript (72.6%), and Nguni (45.3%) cattle because of their heat tolerance (54.7%), tick resistance (54.7%), and milking ability (28.2%) traits. Excessive panting (56.6%) and disease transmission (76%) were regarded as the major effects of heat stress and tick infestation in cattle, respectively. About 50% of the respondents agreed that hair length influences tick resistance and 47.17% considered coat colour when acquiring cattle. In the sampled areas, ticks were prevalent in the summer season (93%), and 77.36% of the respondents use acaricides every fortnight. Gall sickness was reported to be a major problem in the cattle herds by 36.79% of the respondents. Our results showed that farmers in the two municipalities had knowledge of cattle adaptation to heat stress and tick resistance. PMID:25358328

  10. Farmers’ Perceptions and Knowledge of Cattle Adaptation to Heat Stress and Tick Resistance in the Eastern Cape, South Africa

    PubMed Central

    Katiyatiya, C. L. F.; Muchenje, V.; Mushunje, A.

    2014-01-01

    The objective of this study was to determine the perceptions and knowledge of farmers of heat stress and tick resistance in cattle. A cross-sectional survey was conducted and 110 farmers in four villages in the sour and sweet velds of the Eastern Cape Province, South Africa were interviewed. The associations among area (municipality), gender, age, level of education, employment and religion were computed using Chi-square tests. The majority of the respondents had on average 4 bulls, 4 cows, 4 heifers, 4 calves, and 4 oxen. Milk was considered as the major (28.3%) reason for keeping cattle. Most farmers owned non-descript (72.6%), and Nguni (45.3%) cattle because of their heat tolerance (54.7%), tick resistance (54.7%), and milking ability (28.2%) traits. Excessive panting (56.6%) and disease transmission (76%) were regarded as the major effects of heat stress and tick infestation in cattle, respectively. About 50% of the respondents agreed that hair length influences tick resistance and 47.17% considered coat colour when acquiring cattle. In the sampled areas, ticks were prevalent in the summer season (93%), and 77.36% of the respondents use acaricides every fortnight. Gall sickness was reported to be a major problem in the cattle herds by 36.79% of the respondents. Our results showed that farmers in the two municipalities had knowledge of cattle adaptation to heat stress and tick resistance. PMID:25358328

  11. Application of Pre-heating to Improve the Consistency and Quality in AA5052 Resistance Spot Welding

    NASA Astrophysics Data System (ADS)

    Luo, Zhen; Ao, Sansan; Chao, Yuh Jin; Cui, Xuetuan; Li, Yang; Lin, Ye

    2015-10-01

    Making consistent resistance spot welds of aluminum alloy with good quality and at high volume has several obstacles in automotive industry. One of the difficult issues arises from the presence of a tough non-conducting oxide film on the aluminum sheet surface. The oxide film develops over time and often is non-uniform across the surface of the aluminum alloy sheet, which makes the contact resistance characteristics irregular at the faying interface during welding. The consistency in quality of the final spot welds is therefore problematic to control. To suppress the effect of the irregular oxide film on the spot weld quality, application of a pre-heating treatment in the welding schedule for aluminum alloy 5052 is investigated in this present work. The current level of the pre-heating required to reduce the scatter of the contact resistance at the W/W (workpiece-to-workpiece) faying interface is quantified experimentally. The results indicate that the contact resistance at the W/W faying interface with a pre-heating treatment becomes much consistent and can be reduced by two orders of magnitude. Having the uncertain variation of the contact resistance at the W/W faying surface virtually reduced or removed, the quality of the spot welds in terms of the peak load and nugget diameter is examined and shows a great improvement. The proposed method may provide a robust method for high-volume spot welding of aluminum alloy sheets in auto industry.

  12. Identification and characterization of a heat-resistant protease from Serratia liquefaciens isolated from Brazilian cold raw milk.

    PubMed

    Machado, Solimar Gonçalves; Heyndrickx, Marc; De Block, Jan; Devreese, Bart; Vandenberghe, Isabel; Vanetti, Maria Cristina Dantas; Van Coillie, Els

    2016-04-01

    The cold storage of raw milk before heat treatment in dairy industry promotes the growth of psychrotrophic microorganisms, which are known for their ability to produce heat-resistant proteolytic enzymes. Although Pseudomonas is described as the main causative genus for high proteolytic spoilage potential in dairy products, Serratia liquefaciens secretes proteases and may be found in raw milk samples as well. However, at the present there is no information about the proteolytic spoilage potential of S. liquefaciens in milk after heat-treatment. The main aim of this research was to assess the proteolytic spoilage potential of S. liquefaciens isolated from Brazilian raw milk and to characterize the involved protease. S. liquefaciens was shown to secrete one heat-resistant spoilage metalloprotease of, approximately, 52 kDa encoded by the ser2 gene. The heat-resistance of Ser2 was similar to the aprX encoded metalloprotease produced by Pseudomonas. Although the ser2 gene was detected in all S. liquefaciens isolates tested in this study, the proteolytic activity of the isolates in milk was highly heterogeneous. Since nucleotide and deduced amino acid sequences of ser2 of all tested isolates are identical, this heterogeneity may be attributed to differences in enzyme expression levels or post-translational modifications. PMID:26874224

  13. Materials compatibility of hydride storage materials with austenitic stainless steels

    SciTech Connect

    Clark, E.A.

    1992-09-21

    This task evaluated the materials compatibility of LaNi[sub 5-x]Al[sub x] (x= 0.3, 0.75) hydrides and palladium coated kieselguhr with austenitic stainless steel in hydrogen and tritium process environments. Based on observations of retired prototype hydride storage beds and materials exposure testing samples designed for this study, no materials compatibility problem was indicated. Scanning electron microscopy observations of features on stainless steel surfaces after exposure to hydrides are also commonly found on as-received materials before hydriding. These features are caused by either normal heat treating and acid cleaning of stainless steel or reflect the final machining operation.

  14. Materials compatibility of hydride storage materials with austenitic stainless steels

    SciTech Connect

    Clark, E.A.

    1992-09-21

    This task evaluated the materials compatibility of LaNi{sub 5-x}Al{sub x} (x= 0.3, 0.75) hydrides and palladium coated kieselguhr with austenitic stainless steel in hydrogen and tritium process environments. Based on observations of retired prototype hydride storage beds and materials exposure testing samples designed for this study, no materials compatibility problem was indicated. Scanning electron microscopy observations of features on stainless steel surfaces after exposure to hydrides are also commonly found on as-received materials before hydriding. These features are caused by either normal heat treating and acid cleaning of stainless steel or reflect the final machining operation.

  15. Materials compatibility of hydride storage materials with austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Clark, E. A.

    1992-09-01

    This task evaluated the materials compatibility of LaNi(5-x)Al(x) (x= 0.3, 0.75) hydrides and palladium coated kieselguhr with austenitic stainless steel in hydrogen and tritium process environments. Based on observations of retired prototype hydride storage beds and materials exposure testing samples designed for this study, no materials compatibility problem was indicated. Scanning electron microscopy observations of features on stainless steel surfaces after exposure to hydrides are also commonly found on as-received materials before hydriding. These features are caused by either normal heat treating and acid cleaning of stainless steel or reflect the final machining operation.

  16. Weldable, age hardenable, austenitic stainless steel

    DOEpatents

    Brooks, J.A.; Krenzer, R.W.

    1975-07-22

    An age hardenable, austenitic stainless steel having superior weldability properties as well as resistance to degradation of properties in a hydrogen atmosphere is described. It has a composition of from about 24.0 to about 34.0 weight percent (w/o) nickel, from about 13.5 to about 16.0 w/o chromium, from about 1.9 to about 2.3 w/o titanium, from about 1.0 to about 1.5 w/ o molybdenum, from about 0.01 to about 0.05 w/o carbon, from about 0 to about 0.25 w/o manganese, from about 0 to about 0.01 w/o phosphorous and preferably about 0.005 w/o maximum, from about 0 to about 0.010 w/o sulfur and preferably about 0.005 w/o maximum, from about 0 to about 0.25 w/o silicon, from about 0.1 to about 0.35 w/o aluminum, from about 0.10 to about 0.50 w/o vanadium, from about 0 to about 0.0015 w/o boron, and the balance essentially iron. (auth)

  17. Improving high temperature creep resistance of reduced activation steels by addition of nitrogen and intermediate heat treatment

    NASA Astrophysics Data System (ADS)

    Liu, W. B.; Zhang, C.; Xia, Z. X.; Yang, Z. G.

    2014-12-01

    In the present study, we report an enhanced high-temperature creep resistance in reduced activation ferrite/martensite (RAFM) steels, by introducing nitrogen (0.035 wt%, M3 steel) and employing a novel intermediate heat treatment I-Q-T (intermediate treatment, quenching and tempering). In comparison with all the control groups, the uniaxial tests of the I-Q-T treated M3 steel showed significant increase in rupture time and decrease in elongation. The microstructures of the samples were further characterized to elucidate the origin of the enhanced creep resistance. It is found that, by introducing nitrogen, the primary TaC particles were refined; by employing the I-Q-T heat treatment, the dispersed fine secondary MX precipitates, as well as the lath subgrains containing high-density dislocations, were increased: all are responsible for the improved creep resistance.

  18. The chemical composition of precipitated austenite in 9Ni steel

    NASA Astrophysics Data System (ADS)

    Fultz, B.; Kim, J. I.; Kim, Y. H.; Morris, J. W.

    1986-06-01

    Analytical scanning transmission electron microscopy and a novel Mössbauer spectrometry technique were used to measure the chemical composition of austenite particles which precipitate during intercritical tempering of 9Ni steel. Both techniques showed an enrichment of Ni, Mn, Cr, and Si in the austenite. A straightforward analysis involving data on both austenite composition and austenite formation kinetics suggests that the growth of austenite particles is controlled by a 3-dimensional diffusion process. The segregation of solutes to the austenite accounts for much of its stability against the martensitic transformation at low temperatures. Composition inhomogeneities develop in austenite particles after long temperings; the central regions of the particles are lean in solutes and are first to undergo the martensitic transformation. However, changes in solute concentrations of the austenite during long temperings seem too small to account for the large changes in austenite stability. It appears that some of the stability of precipitated austenite must be microstructural in origin.

  19. Gas chromatography using a resistively heated column with mass spectrometric detection for rapid analysis of pyridine released from Bacillus spores.

    PubMed

    Smith, Philip A; MacDonald, Stephen

    2004-05-21

    Gas chromatography using a resistively heated analytical column with full scan electron impact mass spectrometry (EI-MS) was used to detect pyridine generated from heating Bacillus spores in a custom designed furnace inlet, along with gasoline range aromatic (GRA) hydrocarbons representing an environmental contaminant that could interfere with detection of the biologically-derived compound. Gas phase materials from the furnace inlet were collected onto a section of cooled open tubular column, and carrier gas flow was then routed through the trapping column onto the analytical column. Both sections of column were contained within low thermal mass tubular metal sheaths, with each independently and resistively heated allowing rapid temperature ramps and cooling. An analysis time of 2 min resolved spore-derived pyridine from the other organics, and allowed identification by mass spectrum match. Throughput of 20 analyses per hour was shown to be possible with a 1-min column cool-down time between analyses. PMID:15146930

  20. Instabilities in stabilized austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Ayer, Raghavan; Klein, C. F.; Marzinsky, C. N.

    1992-09-01

    The effect of aging on the precipitation of grain boundary phases in three austenitic stainless steels (AISI 347, 347AP, and an experimental steel stabilized with hafnium) was investigated. Aging was performed both on bulk steels as well as on samples which were subjected to a thermal treatment to simulate the coarse grain region of the heat affected zone (HAZ) during welding. Aging of the bulk steels at 866 K for 8000 hours resulted in the precipitation of Cr23C6 carbides, σ, and Fe2Nb phases; the propensity for precipitation was least for the hafnium-stabilized steel. Weld simulation of the HAZ resulted in dissolution of the phases present in the as-received 347 and 347AP steels, leading to grain coarsening. Subsequent aging caused extensive grain boundary Cr23C6 carbides and inhomogeneous matrix precipitation. In addition, steel 347AP formed a precipitate free zone (PFZ) along the grain boundaries. The steel containing hafnium showed the best microstructural stability to aging and welding.

  1. Comparative proteomic and metabolomic profiling of citrus fruit with enhancement of disease resistance by postharvest heat treatment

    PubMed Central

    2013-01-01

    Background From field harvest to the consumer’s table, fresh citrus fruit spends a considerable amount of time in shipment and storage. During these processes, physiological disorders and pathological diseases are the main causes of fruit loss. Heat treatment (HT) has been widely used to maintain fruit quality during postharvest storage; however, limited molecular information related to this treatment is currently available at a systemic biological level. Results Mature ‘Kamei’ Satsuma mandarin (Citrus unshiu Marc.) fruits were selected for exploring the disease resistance mechanisms induced by HT during postharvest storage. Proteomic analyses based on two-dimensional gel electrophoresis (2-DE), and metabolomic research based on gas chromatography coupled to mass spectrometry (GC-MS), and liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) were conducted. The results show resistance associated proteins were up-regulated in heat treated pericarp, such as beta-1, 3-glucanase, Class III chitinase, 17.7 kDa heat shock protein and low molecular weight heat-shock protein. Also, redox metabolism enzymes were down-regulated in heat treated pericarp, including isoflavone reductase, oxidoreductase and superoxide dismutase. Primary metabolic profiling revealed organic acids and amino acids were down-regulated in heat treated pericarp; but significant accumulation of metabolites, including tetradecanoic acid, oleic acid, ornithine, 2-keto-d-gluconic acid, succinic acid, turanose, sucrose, galactose, myo-inositol, glucose and fructose were detected. Noticeably, H2O2 content decreased, while, lignin content increased in heat treated pericarp compared to the control, which might increase fruit resistibility in response to external stress. Also, flavonoids, substances which are well-known to be effective in reducing external stress, were up-regulated in heat treated pericarp. Conclusions This study provides a broad picture of differential

  2. Development of Low-Cost Austenitic Stainless Gas-Turbine and Diesel Engine Components with Enhanced High-Temperature Reliability

    SciTech Connect

    Maziasz, P.J.; Swindeman, R.W.; Browning, P.F.; Frary, M.E.; Pollard, M.J.; Siebenaler, C.W.; McGreevy, T.E.

    2004-06-01

    In July of 1999, a Cooperative Research and Development Agreement (CRADA) was undertaken between Oak Ridge National Laboratory (ORNL) and Solar Turbines, Inc. and Caterpillar, Inc. (Caterpillar Technical Center) to evaluate commercial cast stainless steels for gas turbine engine and diesel engine exhaust component applications relative to the materials currently being used. If appropriate, the goal was to develop cast stainless steels with improved performance and reliability rather than switch to more costly cast Ni-based superalloys for upgraded performance. The gas-turbine components considered for the Mercury-50 engine were the combustor housing and end-cover, and the center-frame hot-plate, both made from commercial CF8C cast austenitic stainless steel (Fe-l9Cr-12Ni-Nb,C), which is generally limited to use at below 650 C. The advanced diesel engine components considered for truck applications (C10, C12, 3300 and 3400) were the exhaust manifold and turbocharger housing made from commercial high SiMo ductile cast iron with uses limited to 700-750 C or below. Shortly after the start of the CRADA, the turbine materials emphasis changed to wrought 347H stainless steel (hot-plate) and after some initial baseline tensile and creep testing, it was confirmed that this material was typical of those comprising the abundant database; and by 2000, the emphasis of the CRADA was primarily on diesel engine materials. For the diesel applications, commercial SiMo cast iron and standard cast CN12 austenitic stainless steel (Fe-25Cr-13Ni-Nb,C,N,S) baseline materials were obtained commercially. Tensile and creep testing from room temperature to 900 C showed the CN12 austenitic stainless steel to have far superior strength compared to SiMo cast iron above 550 C, together with outstanding oxidation resistance. However, aging at 850 C reduced room-temperature ductility of the standard CN12, and creep-rupture resistance at 850 C was less than expected, which triggered a focused

  3. Impact of transient heat stress on polar lipid metabolism in seedlings of wheat near-isogenic lines contrasting in resistance to hessian fly (Cecidomyiidae) infestation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transient heat stress compromises resistance of host plants to Hessian fly, Mayetiola destructor (Say), and other biotic stresses. However, the mechanism for the loss of plant resistance under heat stress remains to be determined. In this study, we determined polar lipid profiles in control and Hess...

  4. Draft Genome Sequences of Two Heat-Resistant Mutant Strains (A52 and B41) of the Photosynthetic Hydrogen-Producing Bacterium Rhodobacter capsulatus.

    PubMed

    Gokce, Abdulmecit; Cakar, Zeynep Petek; Yucel, Meral; Ozcan, Orhan; Sencan, Sevde; Sertdemir, Ibrahim; Erguner, Bekir; Yuceturk, Betul; Sarac, Aydan; Yuksel, Bayram; Ozturk, Yavuz

    2016-01-01

    The draft genome sequences of two heat-resistant mutant strains, A52 and B41, derived from Rhodobacter capsulatus DSM 1710, and with different hydrogen production levels, are reported here. These sequences may help understand the molecular basis of heat resistance and hydrogen production in R. capsulatus. PMID:27284151

  5. Draft Genome Sequences of Two Heat-Resistant Mutant Strains (A52 and B41) of the Photosynthetic Hydrogen-Producing Bacterium Rhodobacter capsulatus

    PubMed Central

    Gokce, Abdulmecit; Cakar, Zeynep Petek; Yucel, Meral; Ozcan, Orhan; Sencan, Sevde; Sertdemir, Ibrahim; Erguner, Bekir; Yuceturk, Betul; Sarac, Aydan; Yuksel, Bayram

    2016-01-01

    The draft genome sequences of two heat-resistant mutant strains, A52 and B41, derived from Rhodobacter capsulatus DSM 1710, and with different hydrogen production levels, are reported here. These sequences may help understand the molecular basis of heat resistance and hydrogen production in R. capsulatus. PMID:27284151

  6. Effects of alpha-tocopherol addition to polymeric coatings on the UV and heat resistance of a fibrous collagen material--chrome-free leather

    Technology Transfer Automated Retrieval System (TEKTRAN)

    UV and heat resistance are very important qualities of leather because most leather products are constantly exposed to outdoor environments. In recent years, we have focused on using environmentally friendly antioxidants that will improve the UV and heat resistance of chrome-free leather. Tocopher...

  7. Heat treated 9 Cr-1 Mo steel material for high temperature application

    DOEpatents

    Jablonski, Paul D.; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-08-21

    The invention relates to a composition and heat treatment for a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The novel combination of composition and heat treatment produces a heat treated material containing both large primary titanium carbides and small secondary titanium carbides. The primary titanium carbides contribute to creep strength while the secondary titanium carbides act to maintain a higher level of chromium in the finished steel for increased oxidation resistance, and strengthen the steel by impeding the movement of dislocations through the crystal structure. The heat treated material provides improved performance at comparable cost to commonly used high-temperature steels such as ASTM P91 and ASTM P92, and requires heat treatment consisting solely of austenization, rapid cooling, tempering, and final cooling, avoiding the need for any hot-working in the austenite temperature range.

  8. Self-association motifs in the enteroaggregative Escherichia coli heat-resistant agglutinin 1.

    PubMed

    Glaubman, Jessica; Hofmann, Jennifer; Bonney, Megan E; Park, Sumin; Thomas, Jessica M; Kokona, Bashkim; Ramos Falcón, Laura I; Chung, Yoonjie K; Fairman, Robert; Okeke, Iruka N

    2016-07-01

    The heat-resistant agglutinin 1 (Hra1) is an integral outer membrane protein found in strains of Escherichia coli that are exceptional colonizers. Hra1 from enteroaggregative E. coli strain 042 is sufficient to confer adherence to human epithelial cells and to cause bacterial autoaggregation. Hra1 is closely related to the Tia invasin, which also confers adherence, but not autoaggregation. Here, we have demonstrated that Hra1 mediates autoaggregation by self-association and we hypothesize that at least some surface-exposed amino acid sequences that are present in Hra1, but absent in Tia, represent autoaggregation motifs. We inserted FLAG tags along the length of Hra1 and used immune-dot blots to verify that four in silico-predicted outer loops were indeed surface exposed. In Hra1 we swapped nine candidate motifs in three of these loops, ranging from one to ten amino acids in length, to the corresponding sequences in Tia. Three of the motifs were required for Hra1-mediated autoaggregation. The database was searched for other surface proteins containing these motifs; the GGXWRDDXK motif was also present in a surface-exposed region of Rck, a Salmonella enterica serotype Typhimurium complement resistance protein. Cloning and site-specific mutagenesis demonstrated that Rck can confer weak, GGXWRDDXK-dependent autoaggregation by self-association. Hra1 and Rck appear to form heterologous associations and GGXWRDDXK is required on both molecules for Hra1-Rck association. However, a GGYWRDDLKE peptide was not sufficient to interfere with Hra1-mediated autoaggregation. In the present study, three autoaggregation motifs in an integral outer membrane protein have been identified and it was demonstrated that at least one of them works in the context of a different cell surface. PMID:27166217

  9. ELECTRICAL RESISTANCE HEATING OF SOILS AT C-REACTOR AT THE SAVANNAH RIVER SITE

    SciTech Connect

    Blundy, R; Michael Morgenstern, M; Joseph Amari, J; Annamarie MacMurray, A; Mark Farrar, M; Terry Killeen, T

    2007-09-10

    Chlorinated solvent contamination of soils and groundwater is an endemic problem at the Savannah River Site (SRS), and originated as by-products from the nuclear materials manufacturing process. Five nuclear reactors at the SRS produced special nuclear materials for the nation's defense program throughout the cold war era. An important step in the process was thorough degreasing of the fuel and target assemblies prior to irradiation. Discharges from this degreasing process resulted in significant groundwater contamination that would continue well into the future unless a soil remediation action was performed. The largest reactor contamination plume originated from C-Reactor and an interim action was selected in 2004 to remove the residual trichloroethylene (TCE) source material by electrical resistance heating (ERH) technology. This would be followed by monitoring to determine the rate of decrease in concentration in the contaminant plume. Because of the existence of numerous chlorinated solvent sources around SRS, it was elected to generate in-house expertise in the design and operation of ERH, together with the construction of a portable ERH/SVE system that could be deployed at multiple locations around the site. This paper describes the waste unit characteristics, the ERH system design and operation, together with extensive data accumulated from the first deployment adjacent to the C-Reactor building. The installation heated the vadose zone down to 62 feet bgs over a 60 day period during the summer of 2006 and raised soil temperatures to over 200 F. A total of 730 lbs of trichloroethylene (TCE) were removed over this period, and subsequent sampling indicated a removal efficiency of 99.4%.

  10. Density Determination of Liquid Copper and Liquid Nickel by Means of Fast Resistive Pulse Heating and Electromagnetic Levitation

    NASA Astrophysics Data System (ADS)

    Schmon, Alexander; Aziz, Kirmanj; Pottlacher, Gernot

    2015-06-01

    Fast resistive pulse-heating techniques and electromagnetic levitation techniques are capable of determining thermophysical properties of metals in the liquid phase. These properties have become increasingly important as input data for modern numerical simulations. Among others, density is a very relevant parameter for e.g., casting modeling. Density determinations of copper and nickel in their liquid states are performed using a fast resistive pulse-heating setup and a recently build up electromagnetic levitation apparatus. Both methods use optical imaging techniques to determine thermal expansion of the specimen under investigation, but are operating at very different experimental durations. The pulse-heating setup provides a heating of the sample using it as part of an electrical discharge circuit. Heating rates of 108 K/s lead to experimental durations of about 60 µs. Temperature is determined by measuring surface radiance emitted from the sample by a pyrometer. The sample's thermal expansion is monitored by an adapted CCD camera system. The electromagnetic levitation apparatus enables noncontact investigations of samples by levitating and heating them by an induction coil generating inhomogeneous electromagnetic fields. Temperature again is determined by a pyrometer. For thermal expansion determination, shadowgraph images are recorded with a high-speed CCD camera and evaluated with an edge detection algorithm. Thermal expansion then is calculated by averaging several 1000 frames for each temperature point. Investigations of copper and nickel in the liquid state were performed with both techniques and are compared to each other and to literature values.

  11. A novel protein quality control mechanism contributes to heat shock resistance of worldwide-distributed Pseudomonas aeruginosa clone C strains.

    PubMed

    Lee, Changhan; Wigren, Edvard; Trček, Janja; Peters, Verena; Kim, Jihong; Hasni, Muhammad Sharif; Nimtz, Manfred; Lindqvist, Ylva; Park, Chankyu; Curth, Ute; Lünsdorf, Heinrich; Römling, Ute

    2015-11-01

    Pseudomonas aeruginosa is a highly successful nosocomial pathogen capable of causing a wide variety of infections with clone C strains most prevalent worldwide. In this study, we initially characterize a molecular mechanism of survival unique to clone C strains. We identified a P. aeruginosa clone C-specific genomic island (PACGI-1) that contains the highly expressed small heat shock protein sHsp20c, the founding member of a novel subclass of class B bacterial small heat shock proteins. sHsp20c and adjacent gene products are involved in resistance against heat shock. Heat stable sHsp20c is unconventionally expressed in stationary phase in a wide temperature range from 20 to 42°C. Purified sHsp20c has characteristic features of small heat shock protein class B as it is monodisperse, forms sphere-like 24-meric oligomers and exhibits significant chaperone activity. As the P. aeruginosa clone C population is significantly more heat shock resistant than genetically unrelated P. aeruginosa strains without sHsp20c, the horizontally acquired shsp20c operon might contribute to the survival of worldwide-distributed clone C strains. PMID:26014207

  12. Resistant starch content among several sorghum (Sorghum bicolor) genotypes and the effect of heat treatment on resistant starch retention in two genotypes.

    PubMed

    Teixeira, Natália de Carvalho; Queiroz, Valéria Aparecida Vieira; Rocha, Maria Clara; Amorim, Aline Cristina Pinheiro; Soares, Thayana Oliveira; Monteiro, Marlene Azevedo Magalhães; de Menezes, Cícero Beserra; Schaffert, Robert Eugene; Garcia, Maria Aparecida Vieira Teixeira; Junqueira, Roberto Gonçalves

    2016-04-15

    The resistant starch (RS) contents in 49 sorghum genotypes and the effects of heat treatment using dry and wet heat on the grain and flour from two sorghum genotypes were investigated. The results showed a wide variation in the RS contents of the genotypes analyzed. The RS mean values were grouped into six distinct groups and ranged from 0.31±0.33 g/100 g to 65.66±5.46 g/100 g sorghum flour on dry basis. Dry heat causes minor losses in the RS content with retentions of up to 97.19±1.92% of this compound, whereas wet heat retained at most 6.98±0.43% of the RS. The SC 59 and (SSN76)FC6608 RED KAFIR BAZINE (ASA N23) cultivars, which have an average RS content of 65.51 g/100 g, were appropriate for human consumption, and the use of dry heat is presented as a better alternative for the preservation of RS in heat-treated grains. PMID:26616952

  13. Influence of heating rates on in situ resistance measurements of a bronze route Nb Sn Cu Ta multifilamentary conductor

    NASA Astrophysics Data System (ADS)

    Tan, K. S.; Hopkins, S. C.; Glowacki, B. A.

    2004-11-01

    The superconducting properties of a bronze process multifilamentary conductor are controlled by the structure, dimensions and composition of the intermetallic layers, which are strongly influenced by the details of the heat treatments applied to the conductor. It has previously been reported that the electrical resistivity of a Vacuumschmelze bronze process conductor varies during heat treatment, and that analysis of the conductor as a set of parallel resistors allows the features of the resistivity variation to be assigned to the progress of Nb 3Sn intermetallic phase formation. The behaviour of NSP2 Nb-Sn-Cu-Ta bronze process multifilamentary conductors (Imperial Metal Industries) is now reported as a function of the heating rate, in preparation for more complex non-isothermal heat treatment procedures. It is shown that the resistance of the wire measured in situ by an alternating current (AC) technique can be used to observe the progress of the formation of Nb 3Sn, and that the comparison of resistometric measurements at different heating rates can give an indication of other processes (such as recovery and recrystallisation) occurring at lower temperatures during the heating up process prior to isothermal annealing. In addition, this wire containing only about 1% of copper was carefully chosen because of the broken tantalum barriers around individual copper filaments. Therefore, the resistometric measurements were used to attempt to detect the diffusion of tin from the bronze matrix into the copper filaments at lower temperatures without noticeable influence on Nb 3Sn phase formation. Treating the NSP2 wire as a set of parallel resistors also permits estimates to be made of the intermetallic layer thicknesses from resistometric measurements, and these are shown to be in good agreement with estimates from scanning electron microscopy. The difference in critical temperature, Tc, between wires heated at different rates, with the presence of the bronze matrix and

  14. Protein kinase C is involved in resistance to myocardial infarction induced by heat stress.

    PubMed

    Joyeux, M; Baxter, G F; Thomas, D L; Ribuot, C; Yellon, D M

    1997-12-01

    Heat stress (HS) is known to protect against mechanical dysfunction and myocardial necrosis in myocardial ischemia-reperfusion models both in vivo and in vitro. However, the mechanisms involved in this form of cardioprotection remain unclear. Protein kinase C (PKC) and tyrosine kinase activation have both been shown to be involved in the delayed phase of protection following ischemic preconditioning, a phenomenon which appears to be analogous to HS-induced protection. Therefore, we investigated the role of PKC and tyrosine kinase in HS-induced resistance to myocardial infarction, in the isolated rat heart. The selective inhibitors chelerythrine (Che) and genistein (Gen) were used to inhibit PKC and tyrosine kinase, respectively. Rats were treated with Che (5 mg/kg, i.p.) or Gen (5 mg/kg, i.p.) or vehicle before they were either heat stressed (42 degrees C for 15 min) or sham anesthetized. Twenty-four h later their hearts were isolated, retrogradely perfused, and subjected to 35-min occlusion of the left coronary artery followed by 120-min of reperfusion. Infarct-to-risk ratio was significantly reduced in HS (19.9+/-1.1%) compared to sham (43.1+/-1.1%) hearts. This reduction in infarct size was abolished in chelerythrine-treated groups (43.8+/-1.9% in HS+Che v 44.9+/-2.0% in sham+Che), but was conserved in genistein-treated groups (17.7+/-0.9% in HS+Gen v 36.4+/-2.8% in sham+Gen). In order to confirm that genistein at this dose was effectively inhibiting tyrosine kinase activity, we observed the ability of the agent to prevent the hypoglycemic responses to insulin in a separate group of anesthetised rats receiving an i.v. insulin infusion. Western blot analysis of the myocardial hsp72 showed a HS-induced increase of this protein, which was modified by neither the PKC inhibitor, chelerythrine, nor the tyrosine kinase inhibitor, genistein. We conclude that the activation of PKC, but not of tyrosine kinase, appears to play a role in the functional cardioprotection

  15. Dynamic Material Properties of the Heat-Affected Zone (haz) in Resistance SPOT Welding

    NASA Astrophysics Data System (ADS)

    Ha, Ji-Woong; Song, Jung-Han; Huh, Hoon; Lim, Ji-Ho; Park, Sung-Ho

    This paper is concerned with a methodology to identify the dynamic material properties of the heat-affected zone (HAZ) near the base metal in a resistance spot weld process at various strain rates. In order to obtain the dynamic material properties of the HAZ in the spot-welded steel sheet, specimens are prepared to have similar material properties, hardness and microstructure to the actual HAZ. Such thermally simulated specimens are fabricated with the material thermal cycle simulator (MTCS) and compared with the real one for the hardness and microstructure. Dynamic tensile tests are then conducted with a high speed material testing machine. Stress-strain curves of the thermally simulated HAZ are obtained at various strain rates ranged from 0.001/sec to 100/sec. Obtained material properties are applied to the finite element analysis of the spot-welded tensile-shear specimen in order to verify validity of the proposed testing methodology and obtained results. Analysis results demonstrate that the material properties obtained are appropriate for the FE analysis of spot-welded specimens.

  16. Demonstration of Combined Zero-Valent Iron and Electrical Resistance Heating for In Situ Trichloroethene Remediation

    SciTech Connect

    Truex, Michael J.; Macbeth, Tamzen; Vermeul, Vincent R.; Fritz, Brad G.; Mendoza, Donaldo P.; Mackley, Rob D.; Wietsma, Thomas W.; Sandberg, Greg; Powell, Thomas; Powers, Jeff; Pitre, Emile; Michalsen, Mandy M.; Ballock-Dixon, Sage; Zhong, Lirong; Oostrom, Martinus

    2011-06-27

    The effectiveness of in situ treatment using zero-valent iron to remediate sites with non-aqueous phase or significant sediment-associated contaminant mass can be limited by relatively low rates of mass transfer to bring contaminants in contact with the reactive media. For a field test in a trichloroethene source area, combining moderate-temperature (maximum 50oC) subsurface electrical resistance heating with in situ ZVI treatment was shown to accelerate dechlorination and dissolution rates by a factor of 4 to 6 based on organic daughter products and a factor 8-16 using a chloride concentrations. A mass-discharge-based analysis was used to evaluate reaction, dissolution, and volatilization at ambient groundwater temperature (~10oC) and as temperature was increased up to about 50oC. Increased reaction and contaminant dissolution were observed with increased temperature, but volatilization was minimal during the test because in situ reactions maintained low aqueous-phase TCE concentrations.

  17. Resistant starch contents of native and heat-moisture treated jackfruit seed starch.

    PubMed

    Kittipongpatana, Ornanong S; Kittipongpatana, Nisit

    2015-01-01

    Native jackfruit seed starch (JFS) contains 30% w/w type II resistant starch (RS2) and can potentially be developed as a new commercial source of RS for food and pharmaceutical application. Heat-moisture treatment (HMT) was explored as a mean to increase RS content of native JFS. The effect of the conditions was tested at varied moisture contents (MC), temperatures, and times. Moisture levels of 20-25%, together with temperatures 80-110°C, generally resulted in increases of RS amount. The highest amount of RS (52.2%) was achieved under treatment conditions of 25% MC and 80°C, for 16 h (JF-25-80-16). FT-IR peak ratio at 1047/1022 cm(-1) suggested increases in ordered structure in several HMT-JFS samples with increased RS. SEM showed no significant change in the granule appearance, except at high moisture/temperature treatment. XRD revealed no significant change in peaks intensities, suggesting the crystallinity within the granule was mostly retained. DSC showed increases in T g and, in most cases, ΔT, as the MC was increased in the samples. Slight but significant decreases in ΔH were observed in samples with low RS, indicating that a combination of high moisture and temperature might cause partial gelatinization. HMT-JFS with higher RS exhibited less swelling, while the solubility remained mostly unchanged. PMID:25642454

  18. A View of Compatible Heat-Resistant Alloy and Coating Systems at High-Temperatures

    SciTech Connect

    Narita, Toshio

    2009-09-14

    Conventional and advanced coatings were reviewed, and it was pointed out that the coated Ni-base superalloys decreased their creep rupture life significantly at higher temperatures, and the advanced high strength superalloy became more remarkably. Concept of diffusion barrier coating system (DBC system) and their formation process was introduced, and the results obtained for several heat-resistant alloys, stainless steel (SUS310S), Ni-Mo base alloy (Hastelloy-X), and 4{sup th} generation single crystal superalloy (TMS-138) were given. It was noted that creep-rupture life of the SUS310S and Hastelloy-X with the DBC system became longer than those of the bare alloys with or without conventional {beta}-NiAl coatings. This is due to slow creep-deformation of the Re-base alloy layer as the diffusion barrier. A novel concept based on combination of superalloys and coatings was proposed, by taking both the materials science and corrosion science into consideration.

  19. Resistant Starch Contents of Native and Heat-Moisture Treated Jackfruit Seed Starch

    PubMed Central

    Kittipongpatana, Ornanong S.

    2015-01-01

    Native jackfruit seed starch (JFS) contains 30% w/w type II resistant starch (RS2) and can potentially be developed as a new commercial source of RS for food and pharmaceutical application. Heat-moisture treatment (HMT) was explored as a mean to increase RS content of native JFS. The effect of the conditions was tested at varied moisture contents (MC), temperatures, and times. Moisture levels of 20–25%, together with temperatures 80–110°C, generally resulted in increases of RS amount. The highest amount of RS (52.2%) was achieved under treatment conditions of 25% MC and 80°C, for 16 h (JF-25-80-16). FT-IR peak ratio at 1047/1022 cm−1 suggested increases in ordered structure in several HMT-JFS samples with increased RS. SEM showed no significant change in the granule appearance, except at high moisture/temperature treatment. XRD revealed no significant change in peaks intensities, suggesting the crystallinity within the granule was mostly retained. DSC showed increases in Tg and, in most cases, ΔT, as the MC was increased in the samples. Slight but significant decreases in ΔH were observed in samples with low RS, indicating that a combination of high moisture and temperature might cause partial gelatinization. HMT-JFS with higher RS exhibited less swelling, while the solubility remained mostly unchanged. PMID:25642454

  20. Heat-resistant agglutinin 1 is an accessory enteroaggregative Escherichia coli colonization factor.

    PubMed

    Bhargava, Samhita; Johnson, Brandon B; Hwang, Jennifer; Harris, Tamia A; George, Anu S; Muir, Amanda; Dorff, Justin; Okeke, Iruka N

    2009-08-01

    Enteroaggregative Escherichia coli (EAEC) is an important cause of acute and persistent diarrhea. The defining stacked brick adherence pattern of Peruvian EAEC isolate 042 has previously been attributed to aggregative adherence fimbriae II (AAF/II), which confer aggregative adherence on laboratory E. coli strains. EAEC strains also show exceptional autoaggregation and biofilm formation, other phenotypes that have hitherto been ascribed to AAF/II. We report that EAEC 042 carries the heat-resistant agglutinin (hra1) gene, also known as hek, which encodes an outer membrane protein. Like AAF/II, the cloned EAEC 042 hra1 gene product is sufficient to confer autoaggregation, biofilm formation, and aggregative adherence on nonadherent and nonpathogenic laboratory E. coli strains. However, an 042 hra1 deletion mutant is not deficient in these phenotypes compared to the wild type. EAEC strain 042 produces a classic honeycomb or stacked brick pattern of adherence to epithelial cells. Unlike wild-type 042, the hra1 mutant typically does not form a tidy stacked brick pattern on HEp-2 cells in culture, which is definitive for EAEC. Moreover, the hra1 mutant is significantly impaired in the Caenorhabditis elegans slow kill colonization model. Our data suggest that the exceptional colonization of strain 042 is due to multiple factors and that Hra1 is an accessory EAEC colonization factor. PMID:19482929

  1. Structural transformations in heat-resistant protective coatings on nickel alloys

    SciTech Connect

    Veksler, Yu.G.; Lesnikov, V.P.; Paleeva, S.Ya.; Lesnikova, E.G.; Myal'nitsa, G.F.

    1987-09-01

    In this work a comprehensive metallophysical study was carried out for two aluminosilicide slip coatings of the systems Al-Si and Al-Nb-Si and an electron-beam Co-Cr-Al-Y coating on alloy EP-539 (17...19% Cr, 4...6% Co, 2.5...4% W, 4.5...6.5% Mo, 2...3% Ti, 3...4% Al, 1.4...2% Nb, balance Ni) after high-temperature testing. The protective properties of the coatings were evaluated from the results of laboratory tests for heat resistance at 1000/sup 0/C in the combustion products of diesel fuel with added sulfur at 970, 1000, and 1060/sup 0/C for 100 h and after full-scale tests for 150, 250, 400, and 700 h. Metallographic, hardness, x-ray, and micro x-ray studies of the coating were carried out. Layer-by-layer phase composition and the lattice spacing of the main phases were determined. X-ray analysis was carried out in an a DRON-1 diffractometer in copper K/sub ..-->../-radiation, and x-ray microanalysis was carried out in a MS-46 Cameca microanalyzer

  2. The effect of creep on magnetic domain structure of heat resistant steels

    NASA Astrophysics Data System (ADS)

    Zhang, S. Z.; Tu, S. T.

    2013-04-01

    The magnetic domain and magnetic properties of heat resistant steels including 10CrMo910, P91 and 23CrMoNiWV88 are investigated in the present work. The magnetic properties characterized by magnetic hysteresis loop of the three materials under 500-600°C are measured by vibrating sample magnetometer (VSM). The magnetic domain structure of as-received and crept specimens is observed by magnetic force microscope (MFM). The magnetic domain of ferrite phase change from initial stripe pattern to maze pattern during creep. The black and white fringes and stripe-like pattern have also been found in the P91 and 23CrMoNiWV88 specimens, respectively. The experimental results reveal that the magnetic domain structure is strongly influenced by microstructures with different distributions of the carbides. It is shown that the coercivity and remanence of each material although has a remarkable decrease at 500-600°C especially for P91 almost 64% decrease, it's still the same magnitude as the one at room temperature. All the short-term crept specimens with different creep damage have a linear increase in coercivity and remanence comparing to the as-received 10CrMo910 specimens. These results indicate that it should be possible to develop an in-situ monitoring technology for creep damage based on magnetism measurement.

  3. A View of Compatible Heat-Resistant Alloy and Coating Systems at High-Temperatures

    NASA Astrophysics Data System (ADS)

    Narita, Toshio

    2009-09-01

    Conventional and advanced coatings were reviewed, and it was pointed out that the coated Ni-base superalloys decreased their creep rupture life significantly at higher temperatures, and the advanced high strength superalloy became more remarkably. Concept of diffusion barrier coating system (DBC system) and their formation process was introduced, and the results obtained for several heat-resistant alloys, stainless steel (SUS310S), Ni-Mo base alloy (Hastelloy-X), and 4th generation single crystal superalloy (TMS-138) were given. It was noted that creep-rupture life of the SUS310S and Hastelloy-X with the DBC system became longer than those of the bare alloys with or without conventional β-NiAl coatings. This is due to slow creep-deformation of the Re-base alloy layer as the diffusion barrier. A novel concept based on combination of superalloys and coatings was proposed, by taking both the materials science and corrosion science into consideration.

  4. Microstructural characterization of dissimilar welds between alloy 800 and HP heat-resistant steel

    SciTech Connect

    Dehmolaei, R.; Shamanian, M. Kermanpur, A.

    2008-10-15

    In this study, dissimilar welds between HP heat-resistant steel and Incoloy 800 were made with four different filler materials including: 309 stainless steel and nickel-based Inconel 82, 182 and 617. The microstructure of the base metals, weld metals and their interfaces were characterized by utilizing optical and scanning electron microscopy. Grain boundaries migration in the weld metals was studied. It was found that the migration of grain boundaries in the Inconel 82 weld metal was very extensive. Precipitates of TiC and M{sub 23}C{sub 6} (M = Cr and Mo) in the Inconel 617 weld metal are identified. The necessary conditions for the formation of cracks close to the fusion line of the 309-HP joints are described. Furthermore unmixed zone near the fusion line between HP steel base metal and Inconel 82 weld metal is discussed. An epitaxial growth is characterized at the fusion line of the 309-Alloy 800 and Inconel 617-Alloy 800 joints.

  5. Market Opportunities for Austenitic Stainless Steels in SO2 Scrubbers

    NASA Astrophysics Data System (ADS)

    Michels, Harold T.

    1980-10-01

    Recent U.S. federal legislation has created new opportunities for SO2 scrubbers because all coals, even low-sulfur western coals, will probably require scrubbing to remove SO2 from gaseous combustion products. Scrubbing, the chemical absorption of SO2 by vigorous contact with a slurry—usually lime or limestone—creates an aggressive acid-chloride solution. This presents a promising market for pitting-resistant austenitic stainless steels, but there is active competition from rubber and fiberglass-lined carbon steel. Since the latter are favored on a first-cost basis, stainless steels must be justified on a cost/performance or life-cost basis. Nickel-containing austenitic alloys are favored because of superior field fabricability. Ferritic stainless steels have little utility in this application because of limitations in weldability and resulting poor corrosion resistance. Inco corrosion test spools indicate that molybdenum-containing austenitic alloys are needed. The leanest alloys for this application are 316L and 317L. Low-carbon grades of stainless steel are specified to minimize corrosion in the vicinity of welds. More highly alloyed materials may be required in critical areas. At present, 16,000 MW of scrubber capacity is operational and 17,000 MW is under construction. Another 29,000 MW is planned, bringing the total to 62,000 MW. Some 160,000 MW of scrubber capacity is expected to be placed in service over the next 10 years. This could translate into a total potential market of 80,000 tons of alloy plate for new power industry construction in the next decade. Retrofitting of existing power plants plus scrubbers for other applications such as inert gas generators for oil tankers, smelters, municipal incinerators, coke ovens, the pulp and paper industry, sulfuric acid plants, and fluoride control in phosphoric acid plants will add to this large market.

  6. Mn-Fe base and Mn-Cr-Fe base austenitic alloys

    DOEpatents

    Brager, Howard R.; Garner, Francis A.

    1987-09-01

    Manganese-iron base and manganese-chromium-iron base austenitic alloys designed to have resistance to neutron irradiation induced swelling and low activation have the following compositions (in weight percent): 20 to 40 Mn; up to about 15 Cr; about 0.4 to about 3.0 Si; an austenite stabilizing element selected from C and N, alone or in combination with each other, and in an amount effective to substantially stabilize the austenite phase, but less than about 0.7 C, and less than about 0.3 N; up to about 2.5 V; up to about 0.1 P; up to about 0.01 B; up to about 3.0 Al; up to about 0.5 Ni; up to about 2.0 W; up to about 1.0 Ti; up to about 1.0 Ta; and with the remainder of the alloy being essentially iron.

  7. Mn-Fe base and Mn-Cr-Fe base austenitic alloys

    DOEpatents

    Brager, Howard R.; Garner, Francis A.

    1987-01-01

    Manganese-iron base and manganese-chromium-iron base austenitic alloys designed to have resistance to neutron irradiation induced swelling and low activation have the following compositions (in weight percent): 20 to 40 Mn; up to about 15 Cr; about 0.4 to about 3.0 Si; an austenite stabilizing element selected from C and N, alone or in combination with each other, and in an amount effective to substantially stabilize the austenite phase, but less than about 0.7 C, and less than about 0.3 N; up to about 2.5 V; up to about 0.1 P; up to about 0.01 B; up to about 3.0 Al; up to about 0.5 Ni; up to about 2.0 W; up to about 1.0 Ti; up to about 1.0 Ta; and with the remainder of the alloy being essentially iron.

  8. Passive Warming using a Heat-Band versus a Resistive Heating Blanket for the Prevention of Inadvertent Perioperative Hypothermia during Laparotomy for Gynaecological Surgery

    PubMed Central

    Wan Fadzlina, Wan Muhd Shukeri; Wan Mohd Nazaruddin, Wan Hassan; Rhendra Hardy, Mohamad Zaini

    2016-01-01

    Background Inadvertent perioperative hypothermia (IPH) is a common problem, despite advancements in a variety of warming systems. The use of a resistive heating blanket (RHB) is a common but costly approach to patient warming. We have introduced the use of a heat-band in our centre as a cost-effective alternative to the RHB for patient warming. The efficacy of the heat-band in preventing IPH during laparotomy for gynaecological surgeries was compared with that of the RHB. Methods Thirty-two patients undergoing surgeries under combined general-epidural anaesthesia, with an expected duration of surgery of 2–4 h, were randomised to receive either the heat-band or RHB. The core body temperatures of the two groups were compared at several perioperative times, in addition to the incidence of post-anaesthesia shivering, time to extubation and intraoperative blood loss. Results The core body temperatures were comparable between the two groups in the pre-operative period, immediately after the induction of anaesthesia and skin incision, 1 h after the incision, at the time of complete skin closing, at extubation, upon arrival to the recovery room and 1 h post-operatively. There were no significant between-group differences in the incidence of post-anaesthesia shivering, time to extubation and intra-operative blood loss. Conclusion The heat-band is as effective as the RHB in preventing IPH and its complications in gynaecological laparotomies. PMID:27547112

  9. Evaluation of composites made from blends of cotton burs, cotton stalks, kenaf, flax, and southern pine: Heat treatments to improve physical and mechanical properties and rot resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experiments were conducted on composite board blends of cotton burs (B), cotton stalks (S), kenaf (K), flax, (F), and southern yellow pine (P). The composite boards were subjected to heat treatments and rot resistance testing. Heat treatments consisted of heating fibers either pre- or post-board fab...

  10. Modifications in membrane fatty acid composition of Salmonella typhimurium in response to growth conditions and their effect on heat resistance.

    PubMed

    Alvarez-Ordóñez, Avelino; Fernández, Ana; López, Mercedes; Arenas, Ricardo; Bernardo, Ana

    2008-04-30

    The effects of growth temperature (in the range 10-45 degrees C) and acidification up to pH 4.5 of the culture medium (Brain Heart Infusion, BHI) with different organic acids (acetic, citric and lactic) and hydrochloric acid on membrane fatty acid composition and heat resistance of Salmonella typhimurium CECT 443 were studied. The heat resistance was maximal in cells grown at 45 degrees C (cells grown in non-acidified BHI showed a D58-value of 0.90 min) and decreased with decreasing growth temperature up to 10 degrees C (D58-value of 0.09 min). The growth of cells in acidified media caused an increase in their heat resistance. In general, acid adapted cells showed D-values of between 1.5 and 2 times higher than the corresponding for non-acid adapted control cells. This cross-protection response, which has important implications in food processing, was not dependent on the pH value and the acid used to acidify the growth medium. A membrane adaptation corresponding to an increase in the unsaturated to saturated fatty acids ratio (UFA/SFA) and membrane fluidity was observed at low growth temperature. Moreover, the acidification of the growth medium caused a decrease in UFA/SFA ratio and in the C18:1 relative concentration, and an increase in cyclopropane fatty acids (CFA) content mainly due to the increase in cyc19 relative concentration. Thus, acid adapted cells showed CFA levels 1.5 times higher than non-acid adapted control cells. A significant proportion of unsaturated fatty acids were converted to their cyclopropane derivatives during acid adaptation. These changes in membrane fatty acid composition result in cells with decreased membrane fluidity. A clear relation between membrane fatty acid composition and heat resistance was observed. In general, D-values were maximum for cells with low UFA/SFA ratio, and, consequently, with low membrane fluidity. Moreover, CFA formation played a major role in protecting acid adapted cells from heat inactivation. However

  11. Effect of NaCl on heat resistance, antibiotic susceptibility, and Caco-2 cell invasion of Salmonella.

    PubMed

    Yoon, Hyunjoo; Park, Beom-Young; Oh, Mi-Hwa; Choi, Kyoung-Hee; Yoon, Yohan

    2013-01-01

    This study evaluated the effects of NaCl on heat resistance, antibiotic susceptibility, and Caco-2 cell invasion of Salmonella. Salmonella typhimurium NCCP10812 and Salmonella enteritidis NCCP12243 were exposed to 0, 2, and 4% NaCl and to sequential increase of NaCl concentrations from 0 to 4% NaCl for 24 h at 35°C. The strains were then investigated for heat resistance (60°C), antibiotic susceptibility to eight antibiotics, and Caco-2 cell invasion efficiency. S. typhimurium NCCP10812 showed increased thermal resistance (P < 0.05) after exposure to single NaCl concentrations. A sequential increase of NaCl concentration decreased (P < 0.05) the antibiotic sensitivities of S. typhimurium NCCP10812 to chloramphenicol, gentamicin, and oxytetracycline. NaCl exposure also increased (P < 0.05) Caco-2 cell invasion efficiency of S. enteritidis NCCP12243. These results indicate that NaCl in food may cause increased thermal resistance, cell invasion efficiency, and antibiotic resistance of Salmonella. PMID:23936782

  12. Effect of repeated structural recrystallization of grade 20 steel on corrosion resistance of pipes of heating surfaces

    NASA Astrophysics Data System (ADS)

    Pomazova, A. V.; Panova, T. V.; Gering, G. I.

    2015-04-01

    The necessity to enhance the operating characteristics of boiler steels is related to a continuous increase in corrosion damages of pipes of heating surfaces. Therefore, the actual task remains the development of ways to enhance the corrosion resistance of pipes made of grade 20, which are used as heat-absorbing elements in heat power engineering. The effect of cyclic modes of normalization (repeated structural recrystallization) on microstructural characteristics and the mechanical and corrosion properties of grade 20 steel in accordance with the regulatory requirements for products of this kind is studied. It is established that twofold normalization for grade 20 carbon steel is the optimum heat treatment mode for equalizing the ferrite grain sizes and decreasing the corrosion rate. It is revealed that this heat treatment mode increases the inequigranularity factor by three times in comparison with the original magnitude. Subsequent normalization cycles result in the formation of rejected microstructures and a decrease in mechanical properties of metal. The increased homogeneity of the microstructure at the double normalization decreases the corrosion rate by 38-51% of the original magnitude. The obtained results can be used for prolongation of the operation life by a decrease in the corrosion rate in pipes normalized twice as well as for the calculation of the remaining life of heating surfaces of boilers of heat power plants.

  13. Development of Damp-Heat Resistant Self-Primed EVA and Non-EVA Encapsulant Formulations at NREL

    SciTech Connect

    Pern, F. J.; Jorgensen, G. J.

    2005-11-01

    Self-primed ethylene-vinyl acetate (EVA) and non-EVA (PMG) encapsulant formulations were developed that have greater resistance to damp heat exposure at 85 deg C and 85% relative humidity (RH) (in terms of adhesion strength to glass substrates) than a commonly used commercial EVA product. The self-primed EVA formulations were developed on the basis of high-performing glass priming formulations that have previously proven to significantly enhance the adhesion strength of unprimed and primed EVA films on glass substrates during damp heat exposure. The PMG encapsulant formulations were based on an ethylene-methylacrylate copolymer containing glycidyl methacrylate.

  14. Combined resistive and laser heating technique for in situ radial X-ray diffraction in the diamond anvil cell at high pressure and temperature

    SciTech Connect

    Miyagi, Lowell; Kanitpanyacharoen, Waruntorn; Kaercher, Pamela; Wenk, Hans-Rudolf; Alarcon, Eloisa Zepeda; Raju, Selva Vennila; Knight, Jason; MacDowell, Alastair; Williams, Quentin

    2013-02-15

    To extend the range of high-temperature, high-pressure studies within the diamond anvil cell, a Liermann-type diamond anvil cell with radial diffraction geometry (rDAC) was redesigned and developed for synchrotron X-ray diffraction experiments at beamline 12.2.2 of the Advanced Light Source. The rDAC, equipped with graphite heating arrays, allows simultaneous resistive and laser heating while the material is subjected to high pressure. The goals are both to extend the temperature range of external (resistive) heating and to produce environments with lower temperature gradients in a simultaneously resistive- and laser-heated rDAC. Three different geomaterials were used as pilot samples to calibrate and optimize conditions for combined resistive and laser heating. For example, in Run1, FeO was loaded in a boron-mica gasket and compressed to 11 GPa then gradually resistively heated to 1007 K (1073 K at the diamond side). The laser heating was further applied to FeO to raise temperature to 2273 K. In Run2, Fe-Ni alloy was compressed to 18 GPa and resistively heated to 1785 K (1973 K at the diamond side). The combined resistive and laser heating was successfully performed again on (Mg{sub 0.9}Fe{sub 0.1})O in Run3. In this instance, the sample was loaded in a boron-kapton gasket, compressed to 29 GPa, resistive-heated up to 1007 K (1073 K at the diamond side), and further simultaneously laser-heated to achieve a temperature in excess of 2273 K at the sample position. Diffraction patterns obtained from the experiments were deconvoluted using the Rietveld method and quantified for lattice preferred orientation of each material under extreme conditions and during phase transformation.

  15. Mechanical properties of steels with a microstructure of bainite/martensite and austenite islands

    NASA Astrophysics Data System (ADS)

    Syammach, Sami M.

    Advanced high strength steels (AHSS) are continually being developed in order to reduce weight and improve safety for automotive applications. There is need for economic steels with improved strength and ductility combinations. These demands have led to research and development of third generation AHSS. Third generation AHSS include steel grades with a bainitic and tempered martensitic matrix with retained austenite islands. These steels may provide improved mechanical properties compared to first generation AHSS and should be more economical than second generation AHSS. There is a need to investigate these newer types of steels to determine their strength and formability properties. Understanding these bainitic and tempered martensitic steels is important because they likely can be produced using currently available production systems. If viable, these steels could be a positive step in the evolution of AHSS. The present work investigates the effect of the microstructure on the mechanical properties of steels with a microstructure of bainite, martensite, and retained austenite, so called TRIP aided bainitic ferrite (TBF) steels. The first step in this project was creating the desired microstructure. To create a microstructure of bainite, martensite, and austenite an interrupted austempering heat treatment was used. Varying the heat treatment times and temperatures produced microstructures of varying amounts of bainite, martensite, and austenite. Mechanical properties such as strength, ductility, strain hardening, and hole-expansion ratios were then evaluated for each heat treatment. Correlations between mechanical properties and microstructure were then evaluated. It was found that samples after each of the heat treatments exhibited strengths between 1050 MPa and 1350 MPa with total elongations varying from 8 pct to 16 pct. By increasing the bainite and austenite volume fraction the strength of the steel was found to decrease, but the ductility increased. Larger

  16. Study of the influence of sporulation conditions on heat resistance of Geobacillus stearothermophilus used in the development of biological indicators for steam sterilization.

    PubMed

    Guizelini, Belquis P; Vandenberghe, Luciana P S; Sella, Sandra Regina B R; Soccol, Carlos Ricardo

    2012-12-01

    Biological indicators are important tools in infection control via sterilization process monitoring. The use of a standardized spore crop with a well-defined heat resistance will guarantee the quality of a biological indicator. Ambient factors during sporulation can affect spore characteristics and properties, including heat resistance. The aim of this study is to evaluate the main sporulation factors responsible for heat resistance in Geobacillus stearothermophilus, a useful biological indicator for steam sterilization. A sequence of a three-step optimization of variables (initial pH, nutrient concentration, tryptone, peptone, beef extract, yeast extract, manganese sulfate, magnesium sulfate, calcium chloride and potassium phosphate) was carried out to screen those that have a significant influence on heat resistance of produced spores. The variable exerting greatest influence on G. stearothermophilus heat resistance during sporulation was found to be the initial pH. Lower nutrient concentration and alkaline pH around 8.5 tended to enhance decimal reduction time at 121 °C (D(121°C)). A central composite design enabled a fourfold enhancement in heat resistance, and the model obtained accurately describes positive pH and negative manganese sulfate concentration influence on spore heat resistance. PMID:22872104

  17. Characteristics of heat resistant alloys Ti10Nb45Al and Ti18Nb48Al

    SciTech Connect

    Weijun Zhang; Guoliang Chen; Yandong Wang; Zuqing Sun )

    1993-05-01

    Based on a systematic study of the ternary Ti-Nb-Al system, two attractive heat resistant alloys, Ti10Nb45Al and Ti18Nb48Al, were developed, and the characteristics of these alloys were discussed: (1) After annealing at 1,200 C for 240 h and furnace cooling to room temperature, the Ti10Nb45Al alloy exhibits an [alpha][sub 2] + [gamma] lamellar microstructure, and the Ti18Nb48Al alloy shows a plate-like structure consisting of [alpha][sub 2], [gamma] and [gamma][sub 1] phases. (2) The specific strengths of Ti10Nb45Al and Ti18Nb48Al are much higher than TiAl and superalloys in the temperature range of 800 [approximately] 1,100 C. The compressive yield strengths of these alloys are on the order of 700 MPa at 800 C and 350 MPa at 1,100 C. The density of these alloys is about 4.3 g/cm[sup 3]. (3) The annealed Ti10Nb45Al and Ti18Nb48Al exhibit some ductility at room temperature, with the compressive elongation on the order of 12% and the fracture toughness as high as 16 MPa[radical]m. The ductile-brittle transformation temperatures for Ti10Nb45Al and Ti18Nb48Al are 650 C and 750 C, respectively. (4) The parabolic constant K[sub p] for oxidation of Ti10Nb45Al and Ti18Nb48Al are 0.88 and 0.29 mg[sup 2]cm[sup [minus]4]h[sup [minus]1] respectively, which are two orders of magnitude lower than that of TiAl and Ti[sub 3]Al alloys.

  18. Heat shock proteins and resistance to desiccation in congeneric land snails.

    PubMed

    Mizrahi, Tal; Heller, Joseph; Goldenberg, Shoshana; Arad, Zeev

    2010-07-01

    Land snails are subject to daily and seasonal variations in temperature and in water availability and depend on a range of behavioral and physiological adaptations for coping with problems of maintaining water, ionic, and thermal balance. Heat shock proteins (HSPs) are a multigene family of proteins whose expression is induced by a variety of stress agents. We used experimental desiccation to test whether adaptation to different habitats affects HSP expression in two closely related Sphincterochila snail species, a desiccation-resistant, desert species Sphincterochila zonata, and a Mediterranean-type, desiccation-sensitive species Sphincterochila cariosa. We examined the HSP response in the foot, hepatopancreas, and kidney tissues of snails exposed to normothermic desiccation. Our findings show variations in the HSP response in both timing and magnitude between the two species. The levels of endogenous Hsp72 in S. cariosa were higher in all the examined tissues, and the induction of Hsp72, Hsp74, and Hsp90 developed earlier than in S. zonata. In contrary, the induction of sHSPs (Hsp25 and Hsp30) was more pronounced in S. zonata compared to S. cariosa. Our results suggest that land snails use HSPs as part of their survival strategy during desiccation and as important components of the aestivation mechanism in the transition from activity to dormancy. Our study underscores the distinct strategy of HSP expression in response to desiccation, namely the delayed induction of Hsp70 and Hsp90 together with enhanced induction of sHSPs in the desert-dwelling species, and suggests that evolution in harsh environments will result in selection for reduced Hsp70 expression. PMID:19953352

  19. Growth of 3-Inch-Diameter Li2B4O7 Single Crystal Using the Resistance Heating Furnace

    NASA Astrophysics Data System (ADS)

    Sugawara, Tamotsu; Komatsu, Ryuichi; Sugihara, Tadashi

    1994-09-01

    The mode and origin of cracking of lithium tetraborate ( Li2B4O7) single crystals during growth using a resistance heating furnace have been studied. The relationship between the formation mechanism of anomalous growth ridges and the occurrence of cracking was examined. It is concluded that a high temperature gradient near the interface and small temperature fluctuations in the melt are needed for growing a crack-free 3-inch-diameter Li2B4O7 single crystal.

  20. High Strength Stainless Steel Properties that Affect Resistance Welding

    SciTech Connect

    Kanne, W.R.

    2001-08-01

    This report discusses results of a study on selected high strength stainless steel alloy properties that affect resistance welding. The austenitic alloys A-286, JBK-75 (Modified A-286), 21-6-9, 22-13-5, 316 and 304L were investigated and compared. The former two are age hardenable, and the latter four obtain their strength through work hardening. Properties investigated include corrosion and its relationship to chemical cleaning, the effects of heat treatment on strength and surface condition, and the effect of mechanical properties on strength and weldability.

  1. Alumina-forming Austenitic Alloys for Advanced Recuperators

    SciTech Connect

    Pint, Bruce A; Shingledecker, John P; Brady, Michael P; Maziasz, Philip J

    2007-01-01

    Materials selection for thin-walled recuperators has been extensively investigated over the past decade. In the latest generation of recuperated turbine engines, type 347 stainless steel has been replaced by higher alloyed steels and Ni-base chromia-forming alloys. However, high (linear) rates of chromia evaporation in exhaust gas fundamentally limits the oxidation lifetime of these chromia-forming alloys. One solution is to use alumina-forming alloys that are more resistant to this environment. The lower scale growth kinetics and resistance to evaporation in the presence of water vapor suggests an order of magnitude increase in lifetime for alumina-forming alloys. A significant problem with this strategy was the large drop in creep strength with the addition of sufficient Al to form an external alumina scale. However, new Fe-base austenitic compositions have been developed with sufficient strength for this application above 700 C.

  2. The influence of annealing in the ferrite-plus-austenite phase field on the stability of vanadium carbide precipitates

    NASA Technical Reports Server (NTRS)

    Locci, I. E.; Michal, G. M.

    1989-01-01

    The effect of rapid excursions into the ferrite-plus-austenite two-phase field on V4C3 precipitates formed by tempering in the ferrite phases was investigated. Heat treatments were first performed to produce a starting microstructure of fine vanadium carbide particles precipitated in a ferrite matrix, and the microstructure was then subjected to various short-time heat treatment cycles that transformed part of the matrix to austenite. TEM was used to determine the effects of the matrix change on the size, morphology, and distribution of the vanadium carbide particles.

  3. Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by super duplex filler metal

    SciTech Connect

    Eghlimi, Abbas; Shamanian, Morteza; Eskandarian, Masoomeh; Zabolian, Azam; Szpunar, Jerzy A.

    2015-08-15

    In the present paper, microstructural changes across an as-welded dissimilar austenitic/duplex stainless steel couple welded by a super duplex stainless steel filler metal using gas tungsten arc welding process is characterized with optical microscopy and electron back-scattered diffraction techniques. Accordingly, variations of microstructure, texture, and grain boundary character distribution of base metals, heat affected zones, and weld metal were investigated. The results showed that the weld metal, which was composed of Widmanstätten austenite side-plates and allotriomorphic grain boundary austenite morphologies, had the weakest texture and was dominated by low angle boundaries. The welding process increased the ferrite content but decreased the texture intensity at the heat affected zone of the super duplex stainless steel base metal. In addition, through partial ferritization, it changed the morphology of elongated grains of the rolled microstructure to twinned partially transformed austenite plateaus scattered between ferrite textured colonies. However, the texture of the austenitic stainless steel heat affected zone was strengthened via encouraging recrystallization and formation of annealing twins. At both interfaces, an increase in the special character coincident site lattice boundaries of the primary phase as well as a strong texture with <100> orientation, mainly of Goss component, was observed. - Graphical abstract: Display Omitted - Highlights: • Weld metal showed local orientation at microscale but random texture at macroscale. • Intensification of <100> orientated grains was observed adjacent to the fusion lines. • The austenite texture was weaker than that of the ferrite in all duplex regions. • Welding caused twinned partially transformed austenites to form at SDSS HAZ. • At both interfaces, the ratio of special CSL boundaries of the primary phase increased.

  4. Influence of Step Annealing Temperature on the Microstructure and Pitting Corrosion Resistance of SDSS UNS S32760 Welds

    NASA Astrophysics Data System (ADS)

    Yousefieh, M.; Shamanian, M.; Saatchi, A.

    2011-12-01

    In the present work, the influence of step annealing heat treatment on the microstructure and pitting corrosion resistance of super duplex stainless steel UNS S32760 welds have been investigated. The pitting corrosion resistance in chloride solution was evaluated by potentiostatic measurements. The results showed that step annealing treatments in the temperature ranging from 550 to 1000 °C resulted in a precipitation of sigma phase and Cr2N along the ferrite/austenite and ferrite/ferrite boundaries. At this temperature range, the metastable pits mainly nucleated around the precipitates formed in the grain boundary and ferrite phase. Above 1050 °C, the microstructure contains only austenite and ferrite phases. At this condition, the critical pitting temperature of samples successfully arrived to the highest value obtained in this study.

  5. Irradiation-assisted stress corrosion cracking of model austenitic stainless steel.

    SciTech Connect

    Chung, H. M.; Ruther, W. E.; Strain, R. V.; Shack, W. J.; Karlsen, T. M.

    1999-10-26

    Slow-strain-rate tensile (SSRT) tests were conducted on model austenitic stainless steel (SS) alloys that were irradiated at 289 C in He. After irradiation to {approx}0.3 x 10{sup 21} n {center_dot} cm{sup 2} and {approx} 0.9 x 10{sup 21} n {center_dot} cm{sup -2} (E > 1 MeV), significant heat-to-heat variations in the degree of intergranular and transgranular stress corrosion cracking (IGSCC and TGSCC) were observed. At {approx}0.3 x 10{sup 21} n {center_dot} cm{sup -2}, a high-purity heat of Type 316L SS that contains a very low concentration of Si exhibited the highest susceptibility to IGSCC. In unirradiated state, Types 304 and 304L SS did not exhibit a systematic effect of Si content on alloy strength. However, at {approx}0.3 x 10{sup 21} n {center_dot} cm{sup -2}, yield and maximum strengths decreased significantly as Si content was increased to >0.9 wt.%. Among alloys that contain low concentrations of C and N, ductility and resistance to TGSCC and IGSCC were significantly greater for alloys with >0.9 wt.% Si than for alloys with <0.47 wt.% Si. Initial data at {approx}0.9 x 10{sup 21} n {center_dot} cm{sup -2} were also consistent with the beneficial effect of high Si content. This indicates that to delay onset of and reduce susceptibility to irradiation-assisted stress corrosion cracking (IASCC), at least at low fluence levels, it is helpful to ensure a certain minimum concentration of Si. High concentrations of Cr were also beneficial; alloys that contain <15.5 wt.% Cr exhibited greater susceptibility to IASCC than alloys with {approx}18 wt.% Cr, whereas an alloy that contains >21 wt.% Cr exhibited less susceptibility than the lower-Cr alloys under similar conditions.

  6. Stress corrosion cracking behavior of irradiated model austenitic stainless steel alloys.

    SciTech Connect

    Chung, H. M.; Karlsen, T. M.; Ruther, W. E.; Shack, W. J.; Strain, R. V.

    1999-07-16

    Slow-strain-rate tensile tests (SSRTs) and posttest fractographic analyses by scanning electron microscopy were conducted on 16 austenitic stainless steel (SS) alloys that were irradiated at 289 C in He. After irradiation to {approx}0.3 x 10{sup 21} n{center_dot}cm{sup {minus}2} and {approx}0.9 x 10{sup 21} n{center_dot}cm{sup {minus}2} (E >1 MeV), significant heat-to-heat variations in the degree of intergranular and transgranular stress corrosion cracking (IGSCC and TGSCC) were observed. Following irradiation to a fluence of {approx}0.3 x 10{sup 21} n{center_dot}cm{sup {minus}2}, a high-purity laboratory heat of Type 316L SS (Si {approx} 0.024 wt%) exhibited the highest susceptibility to IGSCC. The other 15 alloys exhibited negligible susceptibility to IGSCC at this low fluence. The percentage of TGSCC on the fracture surfaces of SSRT specimens of the 16 alloys at {approx}0.3 x 10{sup 21} n{center_dot}cm{sup {minus}2} (E > 1 MeV) could be correlated well with N and Si concentrations; all alloys that contained <0.01 wt.% N and <1.0 wt. % Si were susceptible, whereas all alloys that contained >0.01 wt.% N or >1.0 wt.% Si were relatively resistant. High concentrations of Cr were beneficial. Alloys that contain <15.5 wt.% Cr exhibited greater percentages of TGSCC and IGSCC than those alloys with {approx}18 wt.% Cr, whereas an alloy that contains >21 wt.% Cr exhibited less susceptibility than the lower-Cr alloys under similar conditions.

  7. A simple external resistance heating diamond anvil cell and its application for synchrotron radiation x-ray diffraction

    SciTech Connect

    Fan Dawei; Zhou Wenge; Liu Yonggang; Xie Hongsen; Wei Shuyi; Ma Maining

    2010-05-15

    A simple external heating assemblage allowing diamond anvil cell experiments at pressures up to 34 GPa and temperatures up to 653 K was constructed. This cell can be connected to the synchrotron radiation conveniently. The design and construction of this cell are fully described, as well as its applications for x-ray diffraction. Heating is carried out by using an external-heating system, which is made of NiCr resistance wire, and the temperature was measured by a NiCr-NiSi or PtRh-Pt thermocouple. We showed the performance of the new system by introducing the phase transition study of cinnabar ({alpha}-HgS) and thermal equation of state study of almandine at high pressure and temperature with this cell.

  8. Ultrafine-Grained Structure of Fe-Ni-C Austenitic Alloy Formed by Phase Hardening.

    PubMed

    Danilchenko, Vitalij

    2016-12-01

    The X-ray and magnetometry methods were used to study α-γ transformation mechanisms on heating quenched Fe-22.7 wt.% Ni-0.58 wt.% С alloy. Variation of heating rate within 0.03-80 K/min allowed one to switch from diffusive to non-diffusive mechanism of the α-γ transformation. Heating up primary austenitic single crystal specimen at a rate of less than 1.0-0.5 K/min has led to formation of aggregate of grains with different orientation and chemical composition in the reverted austenite. Significant fraction of these grains was determined to have sizes within nanoscale range. PMID:26860715

  9. Laser beam surface melting of high alloy austenitic stainless steel

    SciTech Connect

    Woollin, P.

    1996-12-31

    The welding of high alloy austenitic stainless steels is generally accompanied by a substantial reduction in pitting corrosion resistance relative to the parent, due to microsegregation of Mo and Cr. This prevents the exploitation of the full potential of these steels. Processing to achieve remelting and rapid solidification offers a means of reducing microsegregation levels and improving corrosion resistance. Surface melting of parent UNS S31254 steel by laser beam has been demonstrated as a successful means of producing fine, as-solidified structures with pitting resistance similar to that of the parent, provided that an appropriate minimum beam travel speed is exceeded. The use of N{sub 2} laser trail gas increased the pitting resistance of the surface melted layer. Application of the technique to gas tungsten arc (GTA) melt runs has shown the ability to raise the pitting resistance significantly. Indeed, the use of optimized beam conditions, N{sub 2} trail gas and appropriate surface preparation prior to laser treatment increased the pitting resistance of GTA melt runs to a level approaching that of the parent material.

  10. RESULTS OF CHARACTERIZATION TESTS OF THE SURFACES OF A COMMERCIALLY CARBURIZED AUSTENITIC STAINLESS STEEL

    SciTech Connect

    Farrell, K

    2004-01-07

    A commercial surface carburization treatment that shows promise for hardening the surfaces of the stainless steel target vessel of the Spallation Neutron Source against cavitation erosion and pitting caused by the action of pulsed pressure waves in the liquid mercury target has been investigated. To verify promotional claims for the treatment and to uncover any factors that might be of concern for the integrity of a carburized target vessel, some characterization tests of the nature of the surface layers of carburized austenitic 316LN stainless steel were conducted. The findings support most of the claims. The carburized layer is about 35 {micro}m thick. Its indentation hardness is about five times larger than that of the substrate steel and declines rapidly with depth into the layer. The surface is distorted by the treatment, and the austenite lattice is enlarged. The corrosion resistance of the carburized layer in an acid medium is greater than that for untreated austenite. The layer is not brittle; it is plastically deformable and is quite resistant to cracking during straining. Contrary to the provider's assertations, the maximum carbon content of the layer is much less than 6-7 wt% carbon, and the carbon is not simply contained in supersaturated solid solution; some of it is present in a previously unreported iron carbide phase located at the very surface. Large variations were found in the thickness of the layer, and they signify that controls may be needed to ensure a uniform thickness for treatment of the SNS target vessel. Inclusion stringers and {delta}-ferrite phase embraced in the treated layer are less resistant to chemical attack than the treated austenite. From a cavitation pitting perspective under SNS bombardment, such non-austenitic phases may provide preferential sites for pitting. The shallow depth of the hardened layer will require use of protection measures to avoid mishandling damage to the layer during assembly and installation of a target

  11. Role of Austenite in Brittle Fracture of Bond Region of Super Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kitagawa, Yoshihiko; Ikeuchi, Kenji; Kuroda, Toshio

    Weld simulation of heat-affected zone (HAZ) was performed to investigate the mechanism by which austenite affects the toughness of super duplex stainless steel. Thermal cycles of various peak temperatures in the range from 1373 K to 1673 K corresponding to the HAZ were applied to SAF2507 super duplex stainless steel specimens. Charpy impact test was carried out using the specimens after the weld simulation, and the fracture surfaces were observed by SEM using three-dimensionally reconstruction technique. Austenite content decreased with increasing the peak temperature when the peak temperature exceeded 1473 K and the impact value decreased with increasing the peak temperature and decreasing the austenite content. The thermal cycle of the peak temperature of 1673 K corresponding to weld bond region caused decreasing of austenite content which was 22% lower than that of the base metal. The ductile-brittle transition temperature was measured. As a result the temperature increased rapidly in the weld bond region, the peak temperature of which exceeded 1623 K by the grain growth of ferrite matrix occurring subsequently to the completely dissolution of austenite. The morphology of the fracture surfaces after impact testing at 77 K showed cleavage fracture of ferrite. The {100} orientations of cleavage fracture facets were measured using three-dimensional images of the fracture surfaces and the results were visualized as the orientation color maps. The results showed that there were cleavage fractures consisting of a few facets parallel to each other. It was considered that a few facets existed in one ferrite grain. It was concluded that Widmanstätten austenite divided the large fracture into smaller cleavage facets in a ferrite grain and then suppressed the degradation of bond toughness of duplex stainless steel.

  12. Determination of clothing evaporative resistance on a sweating thermal manikin in an isothermal condition: heat loss method or mass loss method?

    PubMed

    Wang, Faming; Gao, Chuansi; Kuklane, Kalev; Holmér, Ingvar

    2011-08-01

    This paper addresses selection between two calculation options, i.e heat loss option and mass loss option, for thermal manikin measurements on clothing evaporative resistance conducted in an isothermal condition (T(manikin) = T(a) = T(r)). Five vocational clothing ensembles with a thermal insulation range of 1.05-2.58 clo were selected and measured on a sweating thermal manikin 'Tore'. The reasons why the isothermal heat loss method generates a higher evaporative resistance than that of the mass loss method were thoroughly investigated. In addition, an indirect approach was applied to determine the amount of evaporative heat energy taken from the environment. It was found that clothing evaporative resistance values by the heat loss option were 11.2-37.1% greater than those based on the mass loss option. The percentage of evaporative heat loss taken from the environment (H(e,env)) for all test scenarios ranged from 10.9 to 23.8%. The real evaporative cooling efficiency ranged from 0.762 to 0.891, respectively. Furthermore, it is evident that the evaporative heat loss difference introduced by those two options was equal to the heat energy taken from the environment. In order to eliminate the combined effects of dry heat transfer, condensation, and heat pipe on clothing evaporative resistance, it is suggested that manikin measurements on the determination of clothing evaporative resistance should be performed in an isothermal condition. Moreover, the mass loss method should be applied to calculate clothing evaporative resistance. The isothermal heat loss method would appear to overestimate heat stress and thus should be corrected before use. PMID:21669906

  13. Heat transfer and flow resistance of a shell and plate-type evaporator

    SciTech Connect

    Uehara, H.; Stuhltraeger, E.; Miyara, A.; Murakami, H.; Miyazaki, K.

    1997-05-01

    The performance test of a shell-and-plate-type evaporator designed for OTEC plants, geothermal power plants, and heat pump systems is reported. This evaporator contains 30 plates with a unit area of 0.813 m{sup 2}, coated with aluminum powder on the working fluid side. Freon 22 is used as working fluid. Results show an overall heat transfer coefficient of about 5,000 W/(m{sup 2}K) when the heating water velocity is 1M/s. The mean boiling heat transfer coefficient is compared with a precious correlation proposed by Nakaoka and Uehara (1988). The water-side pressure loss is also reported.

  14. Influence of Martensite Fraction on the Stabilization of Austenite in Austenitic-Martensitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Huang, Qiuliang; De Cooman, Bruno C.; Biermann, Horst; Mola, Javad

    2016-05-01

    The influence of martensite fraction ( f α') on the stabilization of austenite was studied by quench interruption below M s temperature of an Fe-13Cr-0.31C (mass pct) stainless steel. The interval between the quench interruption temperature and the secondary martensite start temperature, denoted as θ, was used to quantify the extent of austenite stabilization. In experiments with and without a reheating step subsequent to quench interruption, the variation of θ with f α' showed a transition after transformation of almost half of the austenite. This trend was observed regardless of the solution annealing temperature which influenced the martensite start temperature. The transition in θ was ascribed to a change in the type of martensite nucleation sites from austenite grain and twin boundaries at low f α' to the faults near austenite-martensite (A-M) boundaries at high f α'. At low temperatures, the local carbon enrichment of such boundaries was responsible for the enhanced stabilization at high f α'. At high temperatures, relevant to the quenching and partitioning processing, on the other hand, the pronounced stabilization at high f α' was attributed to the uniform partitioning of the carbon stored at A-M boundaries into the austenite. Reduction in the fault density of austenite served as an auxiliary stabilization mechanism at high temperatures.

  15. The Influence of Arc-Flash and Fire-Resistant Clothing on Thermoregulation during Exercise in the Heat.

    PubMed

    Poirier, Martin P; Meade, Robert D; McGinn, Ryan; Friesen, Brian J; Hardcastle, Stephen G; Flouris, Andreas D; Kenny, Glen P

    2015-01-01

    We evaluated the effect of arc-flash and fire-resistant (AFR) clothing ensembles (CE) on whole-body heat dissipation during work in the heat. On 10 occasions, 7 males performed four 15-min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C), each separated by 15-min of recovery. Whole-body heat loss and metabolic heat production were measured by direct and indirect calorimetry, respectively. Body heat storage was calculated as the temporal summation of heat production and heat loss. Responses were compared in a semi-nude state and while wearing two CE styles: (1) single-piece (coveralls) and (2) two-piece (workpant + long-sleeve shirt). For group 1, there was one non-AFR single-piece CE (CE1STD) and three single-piece CE with AFR properties (CE2AFR, CE3AFR, CE4AFR). For group 2, there was one non-AFR two-piece CE (CE5STD) and four two-piece CE with AFR properties (CE6AFR, CE7AFR, CE8AFR, CE9AFR). The workpants for CE6AFR were not AFR-rated, while a cotton undershirt was also worn for conditions CE8AFR and CE9AFR and for all single-piece CE. Heat storage for all conditions (CE1STD: 328 ± 55, CE2AFR: 335 ± 87, CE3AFR: 309 ± 95, CE4AFR: 403 ± 104, CE5STD: 253 ± 78, CE6AFR: 268 ± 89, CE7AFR: 302 ± 70, CE8AFR: 360 ± 36, CE9AFR: 381 ± 99 kJ) was greater than the semi-nude state (160 ± 124 kJ) (all p ≤ 0.05). No differences were measured between single-piece uniforms (p = 0.273). Among the two-piece uniforms, heat storage was greater for CE8AFR and CE9AFR relative to CE5STD and CE6AFR (all p ≤ 0.05), but not CE7AFR (both p > 0.05). Differences between clothing styles were measured such that greater heat storage was observed in both CE1STD and CE2-4AFR relative to CE5STD. Further, heat storage was greater in CE2AFR and CE4AFR relative to CE6AFR, while it was greater in CE4AFR compared to CE7AFR. Body heat storage during work in the heat was not influenced by the use of AFR fabrics in the single- or two-piece uniforms albeit

  16. Reducing tool wear when machining austenitic stainless steels

    SciTech Connect

    Magee, J.H.; Kosa, T.

    1998-07-01

    Austenitic stainless steels are considered more difficult to machine than carbon steels due to their high work hardening rate, large spread between yield and ultimate tensile strength, high toughness and ductility, and low thermal conductivity. These characteristics can result in a built-up edge or excessive tool wear during machining, especially when the cutting speed is too high. The practical solution is to lower the cutting speed until tool life reaches an acceptable level. However, lower machining speed negatively impacts productivity. Thus, in order to overcome tool wear at relatively high machining speeds for these alloys, on-going research is being performed to improve cutting fluids, develop more wear-resistant tools, and to modify stainless steels to make them less likely to cause tool wear. This paper discusses compositional modifications to the two most commonly machined austenitic stainless steels (Type 303 and 304) which reduced their susceptibility to tool wear, and allowed these grades to be machined at higher cutting speeds.

  17. Biological indicators for low temperature steam formaldehyde sterilization: effect of defined media on sporulation, germination index and moist heat resistance at 110 degrees C of Bacillus strains.

    PubMed

    Hoxey, E V; Soper, C J; Davies, D J

    1985-02-01

    Choice of a biological indicator depends upon selecting a strain with the optimum balance of desirable properties. Screening 20 strains of Bacillus spp. for sporulation on three defined media has shown the wide variation that occurs in requirements for sporulation and properties of the resultant spores. Comparison of germination index and moist heat resistance of resultant spores suggest that a combination of high germination index, high heat resistance and linear inactivation may not be possible. PMID:3980302

  18. Nanoscale characterization of the thermal interface resistance of a heat-sink composite material by in situ TEM.

    PubMed

    Kawamoto, Naoyuki; Kakefuda, Yohei; Mori, Takao; Hirose, Kenji; Mitome, Masanori; Bando, Yoshio; Golberg, Dmitri

    2015-11-20

    We developed an original method of in situ nanoscale characterization of thermal resistance utilizing a high-resolution transmission electron microscope (HRTEM). The focused electron beam of the HRTEM was used as a contact-free heat source and a piezo-movable nanothermocouple was developed as a thermal detector. This method has a high flexibility of supplying thermal-flux directions for nano/microscale thermal conductivity analysis, and is a powerful way to probe the thermal properties of complex or composite materials. Using this method we performed reproducible measurements of electron beam-induced temperature changes in pre-selected sections of a heat-sink α-Al(2)O(3)/epoxy-based resin composite. Observed linear behavior of the temperature change in a filler reveals that Fourier's law holds even at such a mesoscopic scale. In addition, we successfully determined the thermal resistance of the nanoscale interfaces between neighboring α-Al(2)O(3) fillers to be 1.16 × 10(-8) m(2)K W(-1), which is 35 times larger than that of the fillers themselves. This method that we have discovered enables evaluation of thermal resistivity of composites on the nanoscale, combined with the ultimate spatial localization and resolution sample analysis capabilities that TEM entails. PMID:26508524

  19. Nanoscale characterization of the thermal interface resistance of a heat-sink composite material by in situ TEM

    NASA Astrophysics Data System (ADS)

    Kawamoto, Naoyuki; Kakefuda, Yohei; Mori, Takao; Hirose, Kenji; Mitome, Masanori; Bando, Yoshio; Golberg, Dmitri

    2015-11-01

    We developed an original method of in situ nanoscale characterization of thermal resistance utilizing a high-resolution transmission electron microscope (HRTEM). The focused electron beam of the HRTEM was used as a contact-free heat source and a piezo-movable nanothermocouple was developed as a thermal detector. This method has a high flexibility of supplying thermal-flux directions for nano/microscale thermal conductivity analysis, and is a powerful way to probe the thermal properties of complex or composite materials. Using this method we performed reproducible measurements of electron beam-induced temperature changes in pre-selected sections of a heat-sink α-Al2O3/epoxy-based resin composite. Observed linear behavior of the temperature change in a filler reveals that Fourier’s law holds even at such a mesoscopic scale. In addition, we successfully determined the thermal resistance of the nanoscale interfaces between neighboring α-Al2O3 fillers to be 1.16 × 10-8 m2K W-1, which is 35 times larger than that of the fillers themselves. This method that we have discovered enables evaluation of thermal resistivity of composites on the nanoscale, combined with the ultimate spatial localization and resolution sample analysis capabilities that TEM entails.

  20. Electrothermomechanical modeling of out-of-plane deformation in single-stepped beams actuated by resistive heating

    NASA Astrophysics Data System (ADS)

    Najafi Sohi, Ali; Nieva, Patricia M.; Khajepour, Amir

    2015-03-01

    An analytical model for the electrothermomechanical analysis of out-of-plane deformation in resistively heated single-stepped beams is presented. The model takes into account the conductive heat transfer from the beam to the substrate in which it is anchored. It also considers the temperature dependence of the beam material properties and accounts for the locally enhanced resistive heating effect around the release holes in the beam to predict temperature distribution along the beam. Energy method and Euler-Bernoulli beam theory are used for the prediction of out-of-plane deformation and stress distribution of the beam, as well as the out-of-plane rotation at the middle of the beam. The model considers the nonuniformity of the air gap between the beam and the substrate and captures the resultant asymmetric temperature distribution along the beam. The out-of-plane rotations in the middle of the single-stepped beam predicted by the analytical model and measured experimentally agree within 10%. The analytical model is then used to predict the maximum actuation current, which results in high temperature plastic deformation and agrees with the experiments within 5%. The proposed analytical model provides a good approach for systematic design and analysis of out-of-plane electrothermal microactuators based on single-stepped beam design.