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1

UNA PROPUESTA METODOLÓGICA PARA ANALIZAR PROYECTOS FORESTALES DE CAPTURA DE CARBONO EN CUANTO AL APORTE AL DESARROLLO SOSTENIBLE  

Microsoft Academic Search

El presente artículo tuvo como objetivo comparar metodologías de análisis desde los sistemas complejos que involucraran elementos sociales y naturales en interacción entre sí y a diferentes escalas, para ser aplicadas en el estudio de proyectos forestales de captura de carbono. Este tipo de proyectos se denominan mecanismos de mitigación al cambio climático, clasificados dentro del Mecanismo de Desarrollo Limpio

Edgar Moreno Castillo

2011-01-01

2

Joining of Al 6061 alloy to AISI 1018 steel by combined effects of fusion and solid state welding  

Microsoft Academic Search

The joining of a 6-mm thickness Al 6061 to AISI 1018 steel has been performed by the combined effects of fusion and solid state welding. The process is derived from friction stir welding (FSW) but with an adjustable offset of the probe location with respect to the butt line. Metallographic studies by optical microscopy, electron probe microscopy, and the utilization

C. M Chen; R Kovacevic

2004-01-01

3

ESTUDIO DE LA RESISTENCIA AL DESGASTE DE RECUBRIMIENTOS DEPOSITADOS MEDIANTE PROYECCIÓN TÉRMICA SOBRE ACERO AL CARBONO  

Microsoft Academic Search

Coatings of Ni - Al, Ni - SiC, Ni -WC y Ni - W- Co, were deposited and its capacity to protect of the abrasive wear effects on the steel substrate where they were deposited was studied. Coatings were obtained by thermal spraying using oxygen - acetylene combustion gotten by an Eutalloy torch of the Eutectic Castolin trade mark. Materials

SERGIO ECHEVERRI; Estudiante Ingeniería; JULIANA BEDOYA; Estudiante Ingeniería de Materiales; FABIO VARGAS; Ingeniero Metalúrgico

2007-01-01

4

Chemical and mechanical characterization of TiO 2\\/Al 2O 3 atomic layer depositions on AISI 316 L stainless steel  

Microsoft Academic Search

In this work, four different nanometric mono and multi Al2O3 and TiO2 layers have been applied on polished AISI 316 L Stainless Steel substrates by Atomic Layer Depositions (ALD) in order to improve their intrinsic corrosion resistance. The coating morphology has been investigated using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Thickness analysis has been performed using AFM

E. Marin; A. Lanzutti; M. Lekka; L. Guzman; W. Ensinger; L. Fedrizzi

5

A study on the solid-state welding of boron-doped Ni 3Al–AISI 304 stainless steel couple  

Microsoft Academic Search

The solid-state welding of boron-doped Ni3Al intermetallic compound with AISI 304 austenitic stainless steel has been carried out. The interface characteristics of bonding have been examined by using SEM, EDS and XRD. The elasto-plastic analyses on the interface zones of the bonds have been conducted to obtain residual stress induced by different thermal expansion properties of bonded materials. The results

Sukru Yildirim; Mehmet Halidun Kelestemur

2005-01-01

6

Tribological and mechanical properties of Ti/TiAlN/TiAlCN nanoscale multilayer PVD coatings deposited on AISI H11 hot work tool steel  

NASA Astrophysics Data System (ADS)

A new [Ti/TiAlN/TiAlCN]5 multilayer coatings were deposited onto polished substrate AISI H11 (DIN 1.2343) steel by an industrial magnetron sputtering device. The tribological performance of the coated system was investigated by a ball-on-disk tribometer against 100Cr6 steel and Al2O3 balls. The friction coefficients and specific wear rates were measured at various normal loads (2, 5, 8, and 10 N) and sliding velocities (0.2, 0.4, and 0.8 m/s) in ambient air and dry conditions. The phase structure, composition, wear tracks morphologies, hardness, and film/substrate adhesion of the coatings were characterized by light-microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), 3D-surface analyzer, nanoindentation, and scratch tests. Results showed that the deposited coatings showed low wear rates in the scale of 10-15 m3/N m, low friction coefficients against 100Cr6 and Al2O3 balls in the range of 0.25-0.37, and good hardness in the range of 17-20 GPa. Results also revealed that the friction coefficients and disc wear rates decrease and increase, respectively with the increase in normal load and sliding velocity for both coating/Al2O3 and coating/100Cr6 sliding system. Compared with the uncoated-H11 substrate, the deposited coating exhibited superior tribological and mechanical properties. The dominant wear mechanism was abrasive wear for coating/Al2O3 pair, while for coating/100Cr6 pair, a combination of mild adhesive wear, severe adhesive wear, and abrasive wear (extensive plowing) were the dominant wear mechanisms at different applied normal loads.

AL-Bukhaiti, M. A.; Al-hatab, K. A.; Tillmann, W.; Hoffmann, F.; Sprute, T.

2014-11-01

7

Microstructure and Corrosion Properties of AlCoCrFeNi High Entropy Alloy Coatings Deposited on AISI 1045 Steel by the Electrospark Process  

NASA Astrophysics Data System (ADS)

Electrospark deposition (ESD) was employed to clad the AlCoCrFeNi high-entropy alloy (HEA) on AISI 1045 carbon steel. The relationship between the microstructure and corrosion properties of the HEA-coated specimens was studied and compared with that of the copper-molded cast HEA material. Two major microstructural differences were found between the cast HEA material and the HEA coatings. First, the cast material comprises both columnar and equiaxed crystals with a columnar-to-equiaxed transition (CET), whereas the HEA coatings consist of an entirely columnar crystal structure. The CET phenomenon was analyzed based on Hunt's criterion. Second, unlike the cast HEA material, there was no obvious Cr-rich interdendritic segregation and nano-sized precipitate distributed within the dendrites of the HEA coating. With regard to corrosion properties, the corrosion current of the HEA-coated specimen was significantly lower than for the 1045 steel and the cast HEA material. This was attributed to the ESD specimen having a relatively high Cr oxide and Al oxide content at the surface. Moreover, for the ESD specimen, the absence of Cr-rich interdendritic phase and second-phase precipitation resulted in a relatively uniform corrosion attack, which is different from the severe galvanic corrosion attack that occurred in the cast specimen.

Li, Q. H.; Yue, T. M.; Guo, Z. N.; Lin, X.

2013-04-01

8

Microstructure, Mechanical, and Scratch Resistance Properties of TiAlCrNbN-Graded Composite Coating Deposited on AISI H13 Steel Substrate with Pulsed DC Closed Field Unbalanced Magnetron Sputtering Method  

NASA Astrophysics Data System (ADS)

Structure and adhesion properties of TiAlCrNbN coatings were investigated. These coatings were deposited onto AISI H13 steel substrate using pulsed dc closed field unbalanced magnetron sputtering at different deposition parameters including duty cycle, bias voltage, and working pressure. The coatings have been characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The TiAlCrNbN-graded composite coatings have a dense and columnar structure. The X-ray diffraction patterns of coatings exhibited predominantly c-TiAlCrN, h-NbN, and h-TiAlN reflections. Scratch resistance test showed that the highest adhesion strength was attained as 68 N at 2.5 ?s duty time, 100 V bias voltages, and 3 × 10-3 Torr deposition parameters. The lowest adhesion strength was obtained as 55 N at 0.5 ?s duty time, 50V bias voltage, and 2 × 10-3 Torr deposition parameters.

Kara, Levent; Küçükömero?lu, Tevfik; Baran, Özlem; Efeo?lu, ?hsan; Yamamoto, Kenji

2014-04-01

9

Surface fatigue and failure characteristics of hot-forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears  

NASA Technical Reports Server (NTRS)

Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground AISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

Townsend, Dennis P.

1987-01-01

10

Surface fatigue and failure characteristics of hot forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears  

NASA Technical Reports Server (NTRS)

Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground SISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

Townsend, D. P.

1986-01-01

11

Comparing the Formability of AISI 304 and AISI 202 Stainless Steels  

NASA Astrophysics Data System (ADS)

The formability of AISI 202 austenitic stainless steel was compared with that of type AISI 304 stainless steel. Type 202 is a low-nickel austenitic stainless steel alloyed with manganese and nitrogen. In this study, the formability of the two grades was examined using Erichsen cupping tests and room temperature uniaxial tensile tests performed at various angles to the rolling direction. AISI 202 appears to work-harden at a slightly higher rate than AISI 304, even though the austenite in type 202 is more stable than that in 304 with respect to the formation of deformation-induced ?' martensite. Although both grades are predicted to be susceptible to earing during deep drawing, AISI 202 displays a higher work-hardening exponent, higher average normal anisotropy, and a higher limiting drawing ratio than AISI 304. Similar cup heights were measured during Erichsen cupping tests, confirming that the two grades have very similar deep drawing properties. The results of this investigation therefore suggest that AISI 202 is a suitable alternative for AISI 304 in applications requiring good deep drawing properties.

du Toit, M.; Steyn, H. G.

2012-07-01

12

Characterization of borided AISI 316L stainless steel implant  

Microsoft Academic Search

The present study reports on characterization of borided AISI 316L stainless steel implant. Boronizing heat treatment was performed on a cylindrical bar of AISI 316L austenitic surgical stainless steel with a diameter of 2mm and a length of 10mm using slurry salt bath consisting of borax, boric acid and ferro-silicon. The susbstrate AISI 316L was essentially containing 0.022wt% C, 0.79wt%

I. Özbek; B. A. Konduk; C. Bindal; A. H. Ucisik

2002-01-01

13

Pack Cementation Coatings for High-Temperature Oxidation Resistance of AISI 304 Stainless Steel  

NASA Astrophysics Data System (ADS)

Aluminum and titanium are deposited on the surface of steel by the pack cementation method to improve its hot-corrosion and high-temperature oxidation resistance. In this research, coatings of aluminum and titanium and a two-step coating of aluminum and titanium were applied on an AISI 304 stainless steel substrate. The coating layers were examined by carrying out scanning electron microscopy (SEM) and x-ray diffraction (XRD). The SEM results showed that the aluminized coating consisted of two layers with a thickness of 450 ?m each, the titanized coating consisted of two layers with a thickness of 100 ?m each, and the two-step coatings of Al and Ti consisted of three layers with a thickness of 200 ?m each. The XRD investigation of the coatings showed that the aluminized coating consisted of Al2O3, AlCr2, FeAl, and Fe3Al phases; the titanized layers contained TiO2, Ni3Ti, FeNi, and Fe2TiO5 phases; and the two-step coating contained AlNi, Ti3Al, and FeAl phases. The uncoated and coated specimens were subjected to isothermal oxidation at 1050 °C for 100 h. The oxidation results revealed that the application of a coating layer increased the oxidation resistance of the coated AISI 304 samples as opposed to the uncoated ones.

Zandrahimi, Morteza; Vatandoost, Javad; Ebrahimifar, Hadi

2012-10-01

14

Hot hardness characteristics of ausformed AISI M-50, Matrix 2, WD-65, modified AISI 440-C, and Super Nitralloy  

NASA Technical Reports Server (NTRS)

Short-term hot hardness studies were performed with ausformed AISI M-50, Matrix 2, WD-65, modified AISI 440-C (14-4-1) and case hardened Super Nitralloy. Hardness levels of each material were measured at elevated temperatures in an electric furnace with a low oxygen environment. Test temperatures ranged from 294 to 877 K. The hot hardness characteristics of the ausformed AISI-M-50, Matrix 2 WD-65, and modified AISI 440-C were the same as those determined for high-speed tool steels. Hot hardness for these steels can be predicted within one point Rockwell C. The hot hardness characteristics of both the case and core of Super Nitralloy were superior to AISI 52100 but inferior to the high-speed tool steels. The short-term Rockwell C hardness at temperature for the Super Nitralloy material between 294 and 769 K can be predicted within one point Rockwell C hardness.

Chevalier, J. L.; Dietrich, M. W.; Zaretsky, E. V.

1973-01-01

15

The effect of equal channel angular extrusion on the microstructure and mechanical properties of AISI 1552, AISI 4340, and A2 tool steels  

E-print Network

In this investigation, Austenitized AISI 4340 and A2 tool steel were ausformed using ECAE as a sole deformation mechanism. In addition, AISI 1552 steel was deformed by ECAE. The effect of deformation on hardness, tensile properties...

Shadat, Mohammed Anower

1998-01-01

16

Fracture toughness of AISI M2 and AISI M7 high-speed steels  

Microsoft Academic Search

A study has been made of the fracture toughness of AISI M2 and M7 high-speed steels. Fracture toughness of these steels was\\u000a found to depend principally on austenitizing temperature and hardness level. The results are highly reproducible. At usual\\u000a working hardness levels the fracture toughness of M7 and M2 were approximately equal. Instrumented unnotched Charpy tests\\u000a showed M2 to have

A. R. Johnson

1977-01-01

17

JOURNAL DE PHYSIQUE Colloque C2, supplt!ment au no 7, tome 32, Juillet 1971,page C2-112 ANELASTICITY OF AI-Si AND AI-Mg-Si ALLOYS  

E-print Network

-112 ANELASTICITY OF AI-Si AND AI-Mg-Si ALLOYS by K. M. ENTWISTLE University of Manchester Wires of Al-Siand Al results on the alloys containing magnesium due to rapid volatilisation of this element during solution small in the pseudo-binary A1-Mg, Si alloys. For any composition, the peak height varies during ageing

Paris-Sud XI, Université de

18

Effects of low-temperature aging on AISI 444 steel  

NASA Astrophysics Data System (ADS)

The consequences of aging at 400 and 475 °C on the mechanical properties, corrosion resistance, and magnetic properties of the ferritic stainless steel (SS) AISI 444 were investigated. Age hardening was measured as a function of aging time at both temperatures and was found to be more intense at 475 °C. The localized corrosion susceptibility increased, while the impact toughness decreased with aging time. These two effects were also more important at 475 °C. Unlike duplex SSs, AISI 444 did not present any variation in coercive force or Curie temperature with aging time. The effects on the Mössbauer spectra were also determined and analyzed.

Souza, José A.; Abreu, Hamilton F. G.; Nascimento, Alex M.; de Paiva, José A. C.; de Lima-Neto, Pedro; Tavares, Sérgio S. M.

2005-06-01

19

Aluminum-silicon co-deposition by FB-CVD on austenitic stainless steel AISI 316  

NASA Astrophysics Data System (ADS)

Aluminum-silicon coatings were deposited on stainless steel AISI 316 in the temperature range of 540 to 560°C by CVD-FBR. It was used a fluidized bed with 2.5% silicon and 7.5% aluminum powder and 90% inert (alumina). This bed was fluidized with Ar and as an activator a mixture of HCl/H2 in ratios of 1/10 to 1/16. Furthermore, the deposition time of the coatings was varied between 45 minutes to 1.5 hours, with a 50% active gas, neutral gases 50%. Thermodynamic simulation was conducted with the Thermocalc software to get the possible compositions and amount of material deposited for the chosen conditions. The coatings presented the follow compounds FeAl2Si, FeAl2 and Fe2Al5. Aluminum-silicon coatings were heat treated to improve its mechanical properties and its behavior against oxidation for the inter diffusion of the alloying elements. The heat treatment causes the aluminum diffuse into the substrate and the iron diffuse into coating surface. This leads to the transformation of the above compounds in FeAl, Al2FeSi, Cr3Si, AlFeNi and AlCrFe.

Marulanda, J. L.; Perez, F. J.; Remolina-Millán, A.

2013-11-01

20

The characterization of vanadium boride coatings on AISI 8620 steel  

Microsoft Academic Search

Thermodiffusion coatings containing boron and vanadium (B+V) on AISI 8620 steel have been carried out by an initial boronizing in a salt bath consisting of borax, boric acid and ferro-silicon and followed by saturation with vanadium. The properties of the diffusion layer, namely microstructure, phase composition and elemental distribution of the vanadium boride layer, have been studied. The influence of

Saduman Sen

2005-01-01

21

Colloquium on Large Scale Improvement: Implications for AISI  

ERIC Educational Resources Information Center

The Alberta Initiative for School Improvement (AISI) is a province-wide partnership program whose goal is to improve student learning and performance by fostering initiatives that reflect the unique needs and circumstances of each school authority. It is currently ending its third cycle and ninth year of implementation. "The Colloquium on Large…

McEwen, Nelly, Ed.

2008-01-01

22

Effect of bacterium Oceanospirillum on the corrosion potential and oxygen reduction of AISI 4340 steel  

E-print Network

. Electrochemical Data Summary of Corrosion Testing Resultsof AISI 4340 Steel in artificial Seawater at pH=8 . . 2. Electrochemical Data Summary of Corrosion Testing Results of AISI 4340 Steel Covered with Agar in Artificial Sea Water at pH=8 3. Electrochemical... Data Summary of the Corrosion Testing Results of AISI 4340 Steel in ASTM Artificial Seawater + Oceanospirillum 4. Kinetic and Thermodynamic Fixed Parameters for a RDE with Biofilm 5. Component Reaction Orders and Transport Propreties for a RDE...

Popova, Snezana N.

1992-01-01

23

Autogenous Laser Keyhole Welding of AISI 316LTi  

Microsoft Academic Search

Effective autogenous full-penetration welding of 4 mm thick AISI 316LTi austenitic stainless steel bars was achieved using a CO2 laser. The welding process parameters required to obtain an optimal and repeatable procedure giving the best quality welds were identified. The use of side jet of gas suppressing plasma formation was investigated, and it was discovered that there are optimal conditions that

Clayton Damato; Maurizio Fenech; Stephen Abela; John C. Betts; Joseph Buhagiar

2010-01-01

24

Dynamic recrystallization behavior of AISI 304 stainless steel  

Microsoft Academic Search

The dynamic recrystallization (DRX) of AISI 304 stainless steel was studied with torsion test in the temperature range of 900–1100°C and the strain rate range of 5.0×10?2–5.0×100 s?1. The initiation and evolution of DRX were investigated with microstructural analysis and then the critical strain for DRX initiation could be confirmed by analysis of flow stress. The volume fraction of DRX

Sung-Il Kim; Yeon-Chul Yoo

2001-01-01

25

Comparison of pitting fatigue life of ausforged and standard forged AISI M-50 and AISI 9310 spur gears  

NASA Technical Reports Server (NTRS)

Standard forged and ausforged spur gears made of vacuum-induction-melted, consumable-electrode, vacuum-arc-remelted AISI M-50 steel were tested under conditions that produced fatigue pitting. The gears were 8.89 cm (3.5 in.) in pitch diameter and had tip relief. The M-50 standard forged and ausforged test results were compared with each other. They were then compared with results for machined vacuum-arc-remelted AISI 9310 gears tested under identical conditions. Both types of M-50 gears had lives approximately five times that of the 9310 gears. The life at which 10 percent of the M-50 ausforged gears failed was slightly less than that at which the M-50 standard forged gears failed. The ausforged gears had a slightly greater tendency to fail by tooth fracture than did the standard forged gears, most likely because of the better forging and grain flow pattern of standard forged gears.

Townsend, D. P.; Bamberger, E. N.; Zaretsky, E. V.

1975-01-01

26

The growth kinetics of borides formed on boronized AISI 4140 steel  

Microsoft Academic Search

The growth kinetics of boride layer on boronized AISI 4140 steel is reported. Steel samples were boronized in molten borax, boric acid and ferro-silicon bath at 1123, 1173 and 1223K for 2, 4, 6 and 8h, respectively. The morphology and types of borides formed on the surface of AISI 4140 steel substrate were analyzed by means of optical microscopy, scanning

Saduman Sen; Ugur Sen; Cuma Bindal

2005-01-01

27

A study of cumulative fatigue damage in AISI 4130 steel  

NASA Technical Reports Server (NTRS)

Experimental data were obtained using AISI 4130 steel under stress ratios of -1 and 0. A study of cumulative fatigue damage using Miner's and Kramer's equations for stress ratios of -1 and 0 for low-high, low-high-mixed, high-low, and high-low-mixed stress sequences has revealed that there is a close agreement between the theoretical and experimental values of fatigue damage and fatigue life. Kramer's equation predicts less conservative and more realistic cumulative fatigue damage than the popularly used Miner's rule does.

Jeelani, S.; Musial, M.

1986-01-01

28

Effect of nitrogen alloying and the electroslag refining process on the properties of AISI M41 steel  

NASA Astrophysics Data System (ADS)

Nitrogen produces very beneficial effects in high-speed steel and can therefore be regarded as a significant alloying element in ferrous materials. In order to attain the goal of this study, to investigate the effect of nitrogen alloying and the electroslag refining (ESR) process on the properties of AISI M41 steel, two high-speed steels were melted in an air induction furnace (IF). The first one is a standard AISI M41 high-speed steel. The second one is nitrogen-alloyed M41. The produced ingots were used as consumable electrodes in ESR under three different CaF2-based fluxes. The steel produced from the IF and ESR was heat treated. Hardness, secondary hardness, and microstructure were also studied. It was concluded that both ESR and nitrogen alloying improve the hardness profile of the quenched-tempered high-speed steels. The highest secondary hardness and highest softening resistance were attained by ESR of high-nitrogen high-speed steel (M41N) under CaF2/CaO/Al2O3: 55/30/15 slag. The ESR improves the shape, size, and distribution of precipitates in the produced ingot. Quenching and tempering treatment conditions the retained austenite that is present in the as-cast steel by precipitation of carbide and forming martensite on cooling to room temperature.

Mattar, Taha; El Fawakhry, Kamal; Halfa, Hossam; El Demerdash, Mahmoud

2006-12-01

29

Formation of titanium aluminum nitride layers on AISI D2 steel by nitro-titanizing treatment  

NASA Astrophysics Data System (ADS)

In this study, titanium aluminum nitride coating was realized on AISI D2 steels by nitro-titanizing treatment. Steel samples were nitrided at 575 °C for 8 h in the first step of the coating process, and then titanized by thermo-reactive diffusion method in the powder mixture consisting of ferro-titanium, aluminum, ammonium chloride and alumina at 1000 °C for 2 h. The effects of the aluminum content to the coating bath were investigated. The thickness of the titanium aluminum nitride layer formed on the steel samples ranged from 6.30±0.5 to 7.89±0.34?m, depending on the aluminum content. The average micro-hardness value of the layer was 1468 ± 96 HV0.005 and 2630± 83 HV0.005. The phases formed on the coating layers are TiN, AlTi3N and Ti3Al2N2 which are characterized by XRD. EDS analysis results showed that coating layer includes titanium, aluminum and nitrogen.

Cegil, Ozkan; Sen, Saduman

2012-09-01

30

The effect of boronizing and boro-chromizing on tribological performance of AISI 52100 bearing steels  

Microsoft Academic Search

Purpose – The purpose of this paper is to study the tribological behavior of hardened, boronized and boro-chromized AISI 52100 steel balls against boro-chromized AISI 1040 steel disk under 2, 5 and 10 N loads at 0.1 and 0.3 m\\/s sliding speeds. Design\\/methodology\\/approach – Boronizing treatment was realized at 1,000°C for 2 h in a slurry salt bath consisting of

Saduman Sen; Ugur Sen

2009-01-01

31

Using ultrasonic techniques to predict fracture toughness of AISI 4137 alloy steel  

E-print Network

USING ULTRASONIC TECHNIQUES TO PREDICT FRACTURE TOUGHNESS OF AISI 4137 ALLOY STEEL A Thesis by SCOTT PHILLIP MCGRATH Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1997 Major Subject: Mechanical Engineering USING ULTRASONIC TECHNIQUES TO PREDICT FRACTURE TOUGHNESS OF AISI 4137 ALLOY STEEL 'A Thesis by SCOTT PHILLIP MCGRATH Submitted to Texas AdcM University in partial fulfillment...

McGrath, Scott Phillip

1997-01-01

32

Microstructure and intergranular corrosion resistance evaluation of AISI 304 steel for high temperature service  

Microsoft Academic Search

AISI 304 austenitic stainless steel is susceptible to intergranular corrosion when aged in the 450–850 °C temperature range due to chromium depletion at grain boundaries. However, some standard specifications recommend this material for high temperature service in this range (500 °C–800 °C). It is believed that the AISI 304 is able to recover its intergranular corrosion resistance after a short period of time,

A. Yae Kina; V. M. Souza; S. S. M. Tavares; J. M. Pardal; J. A. Souza

2008-01-01

33

Investigation of Boronizing Kinetics of AISI 51100 Steel  

NASA Astrophysics Data System (ADS)

In this study, some mechanical properties of borided AISI 51100 steel with high C concentration were investigated. Boronizing heat treatment was carried out in solid medium consisting of Ekabor-II at 850, 900, and 950 °C for 2, 4, 6, and 8 h. Morphology and mechanical properties of boride layer, and the effect of chemical composition on properties and kinetics of borides were investigated. The results of this study indicated that the morphology of the boride layer has a saw-tooth nature, and its hardness is over 1500 HV. Depending on process time and temperature, the depth of boride layer ranged from 30 to 106 ?m. Optical and SEM studies and XRD analysis revealed that borides formed on the surface of steel substrates have dominantly single Fe2B boride phase in addition to small amount of Cr2B.

Ipek, M.; Celebi Efe, G.; Ozbek, I.; Zeytin, S.; Bindal, C.

2012-05-01

34

Fretting of AISI 9310 and selected fretting resistant surface treatments  

NASA Technical Reports Server (NTRS)

Fretting wear experiments were conducted with uncoated AISI 9310 mating surfaces, and with combinations incorporating a selected coating to one of the mating surfaces. Wear measurements and SEM observations indicated that surface fatigue, as made evident by spallation and surface crack formation, is an important mechanism in promoting fretting wear to uncoated 9310. Increasing humidity resulted in accelerated fretting, and a very noticeable difference in nature of the fretting debris. Of the coatings evaluated, alumimum bronze with a polyester additive was most effective at reducing wear and minimizing fretting damage to the mating uncoated surface, by means of a self-lubricating film that developed on the fretting surfaces. Chromium plate performed as an effective protective coating, itself resisting fretting and not accelerating damage to the uncoated surface.

Bill, R. C.

1977-01-01

35

Fretting of AISI 9310 and selected fretting resistant surface treatments  

NASA Technical Reports Server (NTRS)

Fretting wear experiments were conducted with uncoated AISI 9310 mating surfaces, and with combinations incorporating a selected coating to one of the mating surfaces. Wear measurements and SEM observations indicated that surface fatigue, as made evident by spallation and surface crack formation, is an important mechanism in promoting fretting wear to uncoated 9310. Increasing humidity resulted in accelerated fretting, and a very noticeable difference in nature of the fretting debris. Of the coatings evaluated, aluminum bronze with a polyester additive was most effective at reducing wear and minimizing fretting damage to the mating uncoated surface, by means of a selflubricating film that developed on the fretting surfaces. Chromium plate performed as an effective protective coating, itself resisting fretting and not accelerating damage to the uncoated surface.

Bill, R. C.

1977-01-01

36

Investment cast AISI H13 tooling for automotive applications  

SciTech Connect

While many techniques exist for production of soft tooling, for die casting there is limited recent experience with cast tooling. The most common US alloy used for manufacture of die casting tooling is wrought AISI H13. If the performance of the cast material is comparable to the wrought counterpart, the use of investment cast HI 3 tooling directly from patterns made via rapid prototyping is of considerable interest. A metallurgical study of investment cast H13 was conducted to evaluate the mechanical behavior in simulated die casting applications. Variable thickness plate investment castings of AISI H13 hot work die steel were produced and characterized in the as-cast and heat-treated conditions. The characterization included light microscopy and mechanical testing. Wrought samples of standard and premium grade H13 were heat-treated and characterized similarly for comparison. Microstructural differences were observed in as-cast samples produced in different section thicknesses. Dendrite cell size and carbide morphology constituted the most prominent microstructural differences observed. After a full heat-treatment, microstructural differences between the wrought material and cast materials were slight regardless of section thickness.The mechanical properties of the cast and heat-treated material proved similar to the properties of the standard heat-treated wrought material. A thermal fatigue testing unit was to con-elate the heat checking susceptibility of H13 steel to its processing and consequent microstructural condition. Surface hardness decreased significantly with thermal cycling, and heat checking was observed in as few as 50 cycles. Thermal softening and thermal fatigue susceptibility were quantified and discussed relative to the microstructural conditions created by processing and heat-treatment. It was found that the premium grade wrought H13 steel provided the best overall resistance to heat checking.

Maguire, M.C.; Baldwin, M.D. [Sandia National Labs., Albuquerque, NM (United States); Hochanadel, P.W.; Edwards, G.R. [Colorado School of Mines, Golden, OH (United States)

1995-07-01

37

The Surface Fatigue Life of Contour Induction Hardened AISI 1552 Gears  

NASA Technical Reports Server (NTRS)

Two groups of spur gears manufactured from two different materials and heat treatments were endurance tested for surface fatigue life. One group was manufactured from AISI 1552 and was finished ground to a 0.4 micron (16 micro-in.) rms surface finish and then dual frequency contour induction hardened. The second group was manufactured from CEVM AISI 9310 and was carburized, hardened, and ground to a 0.4 micron (16 micro-in.) rms surface finish. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a maximum Hertz stress of 1.71 GPa (248 ksi), a bulk gear temperature of approximately 350 K (170 F) and a speed of 10,000 rpm. The lubricant used for the tests was a synthetic paraffinic oil with an additive package. The test results showed that the 10 percent surface fatigue (pitting) life of the contour hardened AISI 1552 test gears was 1.7 times that of the carburized and hardened AISI 9310 test gears. Also there were two early failures of the AISI 1552 gears by bending fatigue.

Townsend, Dennis P.; Turza, Alan; Chaplin, Mike

1995-01-01

38

AISI waste oxide recycling program. Final technical report  

SciTech Connect

In March 1995 AISI completed a five-year, $60 million collaborative development program on Direct Steelmaking cost-shared by DOE under the Metals Initiative. This program defined an energy-efficient and environmentally-friendly technology to produce hot metal for steelmaking directly from coal and iron ore pellets without incurring the high capital costs and environmental problems associated with traditional coke oven and blast furnace technology. As it becomes necessary to replace present capacity, this new technology will be favored because of reduced capital costs, higher energy efficiency, and lower operating costs. In April 1994, having failed to move forward with a demonstration plant for direct ironmaking, despite substantial efforts by both Stelco and Geneva Steel, an alternative opportunity was sought to commercialize this new technology without waiting until existing ironmaking capacity needed to be replaced. Recycling and resource recovery of steel plant waste oxides was considered an attractive possibility. This led to approval of a ten-month, $8.3 million joint program with DOE on recycling steel plant waste oxides utilizing this new smelting technology. This highly successful trial program was completed in December 1994. The results of the pilot plant work and a feasibility study for a recycling demonstration plant are presented in this final technical report.

Aukrust, E.; Downing, K.B.; Sarma, B.

1995-08-01

39

Modeling the Flow Curve of AISI 410 Martensitic Stainless Steel  

NASA Astrophysics Data System (ADS)

In the present study, hot deformation behavior of AISI 410 martensitic stainless steel was investigated and modeled after conducting compression tests at the temperature range of 900-1150 °C and strain rate range of 0.001-1 s-1. At the studied temperature and strain rates, the flow curves were typical of dynamic recrystallization (DRX) showing a hardening peak followed by a softening one, and a steady state. The flow curves up to the peaks were modeled using the Estrin and Mecking equation. The softening due to DRX was also considered to increase the consistency of the developed model. The experimental equation proposed by Cingara and McQueen was also used to model the work hardening region. The results showed that the phenomenological model based on the Estrin and Mecking equation resulted in a better model for the work hardening region. Based on the Avrami equation, a model was developed to estimate the flow softening due to DRX between the peak and the starting point of steady state. The average value of the Avrami exponent was determined as 2.2, and it decreased with the increasing Zener-Hollomon parameter.

Momeni, A.; Dehghani, K.; Heidari, M.; Vaseghi, M.

2012-11-01

40

The Forming of AISI 409 sheets for fan blade manufacturing  

SciTech Connect

The necessity of adapting the standardized fan models to conditions of higher temperature has emerged due to the growth of concern referring to the consequences of the gas expelling after the Mont Blanc tunnel accident in Italy and France, where even though, with 100 fans in operation, 41 people died. The objective of this work is to present an alternative to the market standard fans considering a new technology in constructing blades. This new technology introduces the use of the stainless steel AISI 409 due to its good to temperatures of gas exhaust from tunnels in fire situation. The innovation is centered in the process of a deep drawing of metallic sheets in order to keep the ideal aerodynamic superficies for the fan ideal performance. Through the impression of circles on the sheet plane it is shown, experimentally, that, during the pressing process, the more deformed regions on the sheet plane of the blade can not reach the deformation limits of the utilized sheet material.

Foroni, F. D.; Menezes, M. A.; Moreira Filho, L. A. [ITA - Aeronautic Technological Institute, IEM, Praca Mal. Eduardo Gomes, 50 - Vila das Acacias - S. J. Campos, Brasil - CEP 1228-900 (Brazil)

2007-04-07

41

Effect of Cryogenic Treatment on AISI M2 High Speed Steel: Metallurgical and Mechanical Characterization  

NASA Astrophysics Data System (ADS)

This study aims to present the metallurgical and mechanical characterization of cryogenically treated AISI M2 high speed steel (HSS) in terms of carbide precipitation and wear behavior. The samples of commercially available conventionally quenched and tempered AISI M2 HSS were procured and subjected to cryogenic treatment at two levels -110 °C (shallow treatment) and -196 °C (deep treatment) of temperature. The microstructures obtained after cryogenic treatments have been characterized with a prominence to comprehend the influence of cryogenic treatment vis-à-vis conventional quenching and tempering on the nature, size, and distribution of carbides. The mechanical properties such as hardness and wear rate of the specimens have also been compared by performing Rockwell C hardness test and pin-on-disc wear test, respectively. Microstructures, hardness, wear rate and analysis of worn surface reveal the underlying metallurgical mechanism responsible for the improving mechanical properties of the AISI M2 HSS.

Gill, Simranpreet Singh; Singh, Jagdev; Singh, Rupinder; Singh, Harpreet

2012-07-01

42

Coupled Multi-Electrode Investigation of Crevice Corrosion of AISI 316 Stainless Steel  

SciTech Connect

Close packed coupled multi-electrodes arrays (MEA) simulating a planar electrode were used to measure the current evolution as a function of position during initiation and propagation of crevice corrosion of AISI 316 stainless steel. Scaling laws derived from polarization data enabled the use of rescaled crevices providing spatial resolution. Crevice corrosion of AISI 316 stainless steel in 0.6 M NaCl at 50 C was found to initiate close to the crevice mouth and to spread inwards with time. The local crevice current density increased dramatically over a short period to reach a limiting value.

F. Bocher; F. Presuel-Moreno; N.D. Budinasky; J.R. Scully

2006-06-23

43

Improvement of the Electrochemical Behavior of Steel Surfaces Using a [Ti-Al/Ti-Al-N] n Multilayer System  

NASA Astrophysics Data System (ADS)

The aim of this work is to improve the corrosion resistance of AISI D3 steel surfaces using a [Ti-Al/Ti-Al-N] n multilayer system deposited with different periods (?) and bilayer numbers ( n), via magnetron co-sputtering pulsed d.c. procedure, from a metallic (Ti-Al) binary target. The multilayer coatings were characterized by cross-sectional scanning electron microscopy that showed the modulation and microstructure of the [Ti-Al/Ti-Al-N] n multilayer system. The composition of the single Ti-Al and Ti-Al-N layer films was studied via x-ray photoelectron spectroscopy, where typical signals for Ti2p1/2, Ti2p, N1s, and Al2p3/2 were detected. The electrochemical properties were evaluated by electrochemical impedance spectroscopy and Tafel polarization curves. The optimal electrochemical behavior was obtained for the [Ti-Al/Ti-Al-N] n multilayered period of ? = 25 nm (100 bilayers). At these conditions, the maximum polarization resistance (1719.32 k? cm2) and corrosion rate (0.7 ?my) were 300 and 35 times higher than that of uncoated AISI D3 steel substrate (5.61 k? cm2 and 25 ?my, respectively). Finally, scanning electron microscopy was used to analyze the [Ti-Al/Ti-Al-N] n multilayered surface after the corrosive attack. The improvement effects in the electrochemical behavior of the AISI D3 coated with the [Ti-Al/Ti-Al-N] n multilayered coatings could be attributed to the number of interfaces that act as obstacles for the inward and outward diffusions of Cl- ions, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface.

Ipaz, L.; Aperador, W.; Caicedo, J. C.; Esteve, J.; Zambrano, G.

2013-05-01

44

Investigating the Machinability of AISI 420 Stainless Steel Using Factorial Design  

Microsoft Academic Search

This work aims at studying the machining characteristics of high-strength materials using carbide cutting tool inserts at different cutting conditions. This is an essential step in building up an accurate machining information system. The tested material is high-strength stainless steel of the AISI 420 type. Machining tests were carried out using orthogonal cutting conducted to investigate the machining characteristics for

A. M. El-Tamimi; T. M. El-Hossainy

2008-01-01

45

Shielded metal arc welding of AISI 4340 alloy steel. Welding procedure specification  

SciTech Connect

Procedure WPS-115 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for shielded metal arc welding of AISI 4340 alloy steel, in thickness range 0.187 to 2 inch; filler metal is E7018 (F-4, A-1).

Wodtke, C.H.; Frizzell, D.R.; Plunkett, W.A.

1985-08-01

46

Shielded metal arc welding of AISI 4340 alloy steel. Welding procedure specification  

Microsoft Academic Search

Procedure WPS-115 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for shielded metal arc welding of AISI 4340 alloy steel, in thickness range 0.187 to 2 inch; filler metal is E7018 (F-4, A-1).

C. H. Wodtke; D. R. Frizzell; W. A. Plunkett

1985-01-01

47

Variation in sessile microflora during biofilm formation on AISI304 stainless steel coupons  

Microsoft Academic Search

Coupons of stainless steel type AISI-304 were exposed to the industrial cooling system of a petrochemical plant fed by seawater from the Guanabara Bay, Rio de Janeiro, Brazil, in order to study thein situ formation of biofilms. Bacteria, microalgae and fungi were detected on the coupons as soon as 48 h after exposure. Their respective numbers were determined at times

F P de França; M T S Lutterbach

1996-01-01

48

The Mechanical Threshold Stress model for various tempers of AISI 4340 steel  

E-print Network

. In this paper, we determine the Mechanical Threshold Stress model parameters for various tempers of AISI 4340. This paper attempts to redress that lacuna by providing the MTS parameters for a number of tempers of 4340- Cochran-Guinan (SCG) and Burakovsky-Preston-Silbar (BPS) melting temperature models, and the Chen

Utah, University of

49

Experimental investigation on cubic boron nitride turning of hardened AISI 52100 steel  

Microsoft Academic Search

This study investigated the performance and wear behavior of different cubic boron nitride (CBN) tools in finish turning of hardened AISI 52100 steel. Tool performance was evaluated based on the part surface finish and the tool flank wear. Wear conditions of CBN cutting tools were primarily characterized by scanning electron microscopy (SEM). Machining results showed that low CBN content tools

Y. Kevin Chou; Chris J. Evans; Moshe M. Barash

2003-01-01

50

Dissimilar welding of AISI 310 austenitic stainless steel to nickel-based alloy Inconel 657  

Microsoft Academic Search

The current work was carried out to characterize welding of AISI 310 austenitic stainless steel to Inconel 657 nickel–chromium superalloy. The welds were produced using four types of filler materials; the nickel-based corresponding to Inconel 82, Inconel A, Inconel 617 and 310 austenitic stainless steels. This paper describes the selection of welding consumables for the joint. The comparative evaluation was

H. Naffakh; M. Shamanian; F. Ashrafizadeh

2009-01-01

51

Microstructure development in Nd:YAG laser welding of AISI 304 and Inconel 600  

Microsoft Academic Search

In this work, the morphology of solidification of the weld zone (WZ) was studied in a joint formed from dissimilar materials, composed of austenitic AISI 304 stainless steel and Inconel 600 nickel alloy, welded with an Nd:YAG-pulsed laser. The laser beam and optical system parameters were selected with a view to obtain a weld with total penetration and good surface

Maurício David M. das Neves; André Lotto; José Roberto Berretta; Wagner de Rossi; Nilson Dias V. Júnior

2010-01-01

52

Determination of optimum cutting parameters during machining of AISI 304 austenitic stainless steel  

Microsoft Academic Search

High strength, low thermal conductivity, high ductility and high work hardening tendency of austenitic stainless steels are the main factors that make their machinability difficult. In this study determination of the optimum cutting speed has been aimed when turning an AISI 304 austenitic stainless steel using cemented carbide cutting tools. The influence of cutting speed on tool wear and surface

Ihsan Korkut; Mustafa Kasap; Ibrahim Ciftci; Ulvi Seker

2004-01-01

53

Stress relaxation in bending of type AISI304 stainless steel at 773 and 823 K  

Microsoft Academic Search

Stress relaxation measurements at 773 and 823 K in bending and for different initial stresses in type AISI 304 stainless steel are reported. Several thermal treatments were given to the specimens prior to the relaxation testing. The data are fitted to a general equation that describes thermally activated dislocation motion and it is shown that, in some cases, the internal

F. Povolo; R. J. Tinivella; J. F. Reggiardo; G. B. Botteri

1992-01-01

54

Assessment of XM-19 as a Substitute for AISI 348 in ATR Service  

SciTech Connect

It has been proposed that XM-19 alloy be considered as a possible replacement steel for AISI 348 in the construction of Advanced Test Reactor (ATR) capsules. AISI 348 works well, but is currently very difficult to obtain commercially. The superior and desirable mechanical properties of XM-19 alloy have been proven in non-nuclear applications, but no data are available regarding its use in radiation environments. While most 300 series alloys will meet the conditions required in ATR , it cannot be confidently assumed that XM-19 can be substituted without prior qualification in a radiation test. Compared to AISI 348, XM-19 will have an enhanced tendency for phase instabilities due to its higher levels of Ni and, especially, Si. However, transmutation of important elemental components in the highly thermalized ATR spectrum may have a very pronounced effect on its performance during irradiation. Not only will strong transmutation of Mn to Fe reduce the ductility and strength advantages provided by the higher initial Mn content of XM-19, but the extensive loss of Mn will also release from solution much of the N upon which the higher strength of XM-19 depends. In addition, the combined influence of transmutation and Inverse Kirkendall processes may lead to gas-bubble-covered grain boundaries, producing a very fragile alloy after significant irradiation has accumulated. At present, there are no radiation data available to substantiate this possible scenario. An alternate proposal is therefore advanced. Since the response of AISI 348 and 347 to radiation are expected to be relatively indistinguishable, the AISI 347 might serve as an acceptable replacement. While AISI 348 is usually chosen for nuclear service in order to reduce the overall radioactivity arising from relatively small amounts of highly transmutable elements such as cobalt, these elements have very little effect on the radiation performance of the steel. In the proposed application, however, the activity induced in this highly thermalized spectrum to large doses (10 to 50 dpa) will be overwhelmed by the activation arising from the major steel components: Fe, Cr, and especially Ni. The mechanical properties, irradiation creep, and void swelling behavior of the two steels should be practically indistinguishable.

F. A. Garner; L. R. Greenwood; R. E. Mizia; C. R. Tyler

2007-11-01

55

Corrosion behaviour of aisi 304l and 316l stainless steels prepared by powder metallurgy in the presence of sulphuric and phosphoric acid  

Microsoft Academic Search

The corrosion rates of AISI 304L and 316L stainless steels prepared by powder metallurgy (P\\\\M) have been studied by continuous electrochemical methods, in different concentrations of inorganic acid solutions (sulphuric and phosphoric) at room temperature (T = 298 K). For comparison purposes, a simultaneous study was carried out on similar composition cast AISI 304L and AISI 316L stainless steels specially

E Otero; A Pardo; M. V Utrilla; E Sáenz; J. F Álvarez

1998-01-01

56

The corrosion behaviour of AISI 304L AND 316L stainless steels prepared by powder metallurgy in the presence of organic acids  

Microsoft Academic Search

The corrosion rates of AISI 304L and 316L stainless steels prepared by powder metallurgy (P\\/M) have been studied by continuous current electrochemical methods, in organic acid solutions (acetic, formic, lactic and oxalic) at different concentrations. For comparison purposes a simultaneous study was carried out on cast AISI 304L and AISI 316L steels of similar composition. For this investigation polarization resistance

E. Otero; A. Pardo; M. V. Utrilla; F. J. Pérez; C. Merino

1997-01-01

57

Experimental Investigation of the Effect of Burnishing Force on Service Properties of AISI 1010 Steel Plates  

NASA Astrophysics Data System (ADS)

This paper presents the results obtained with a new ball burnishing tool developed for the mechanical treatment of large flat surfaces. Several parameters can affect the mechanical behavior and fatigue of workpiece. Our study focused on the effect of the burnishing force on the surface quality and on the service properties (mechanical behavior, fatigue) of AISI 1010 steel hot-rolled plates. Experimental results assert that burnishing force not exceeding 300 N causes an increase in the ductility. In addition, results indicated that the effect of the burnishing force on the residual surface stress was greater in the direction of advance than in the cross-feed direction. Furthermore, the flat burnishing surfaces did not improve the fatigue strength of AISI 1010 steel flat specimens.

Gharbi, F.; Sghaier, S.; Morel, F.; Benameur, T.

2015-02-01

58

An investigation of the plastic fracture of AISI 4340 and 18 nickel - 200 grade maraging steels  

NASA Technical Reports Server (NTRS)

The mechanisms of plastic fracture (dimpled rupture) in high-purity and commercial 18 Ni, 200 grade maraging steels and quenched and tempered AISI 4340 steels have been studied. Plastic fracture takes place in the maraging alloys through void initiation by fracture of titanium carbo-nitride inclusions and the growth of these voids until impingement results in coalescence and final fracture. The fracture of AISI 4340 steel at a yield strength of 200 ksi occurs by nucleation and subsequent growth of voids formed by fracture of the interface between manganese sulfide inclusions and the matrix. The growth of these inclusion-nucleated voids is interrupted long before coalescence by impingement, by the formation of void sheets which connect neighboring sulfide-nucleated voids.

Cox, T. B.; Low, J. R., Jr.

1974-01-01

59

Behavior of AISI SAE 1020 Steel Implanted by Titanium and Exposed to Bacteria Sulphate Deoxidizer  

NASA Astrophysics Data System (ADS)

A hybrid technology to treat solid surfaces with the pulse high voltage and electric arc discharges of low pressure with a three-dimensional ion implantation technique (3DII) is applied. This technology is used to protect AISI SAE 1020 steel against a microbiological corrosion. The titanium ion implanted steel samples (coupons) are subjected to a medium of bacteria sulphate deoxidizer (BSD) which are very typical of the hydrocarbon industry and are potentially harmful for structures when are in contact with petroleum and some of its derivatives. The used technology aims to find an effective hybrid procedure to minimize the harmful effects of bacteria on AISI SAE 1020 steel. The hybrid technology efficiency of superficial titanium implantation is estimated through the measurements of the point corrosion characteristics obtained after testing both the treated and non-treated coupons. The three-dimensional surface structures of the samples are reconstructed with help of a confocal microscope.

Niño, Ely Dannier V.; Garnica, Hernán; Dugar-Zhabon, Veleriy; Castillo, Genis

2014-05-01

60

Rolling-element fatigue life of AISI M-50 and 18-4-1 balls  

NASA Technical Reports Server (NTRS)

Rolling element fatigue studies were conducted with AISI M-50, EFR 18-4-1, and VAR 18-4-1. Groups of 12.7 mm (1/2-in) diameter balls of each material were tested in the five ball fatigue tester. Test conditions included a load of 1540 N (347 lbf) giving a maximum Hertz stress of 5520 MPa (800 000 psi), a shaft speed of 10,700 rpm, and a contact angle of 30 deg. Tests were run at a race temperature of 339 K (150 F) with a type 2 ester lubricant. The rolling element fatigue life of AISI M-50 was not significantly different from that of EFR 18-4-1 or VAR 18-4-1 based on a statistical comparison of the test results.

Parker, R. J.; Zaretsky, E. V.

1978-01-01

61

Tribological properties of oxidised boride coatings grown on AISI 4140 steel  

Microsoft Academic Search

In this study, we investigated the wear behaviour of borided and borided + short-duration oxidized AISI 4140 steel. Boronizing was carried out in a slurry salt bath consisting of borax, boric acid and ferro silicon. Also, short-duration oxidizing treatment was applied to borided steel to produce glass-like boron oxide layer. The short-duration oxidizing was performed at 750 °C for 3 min. Optical

Saduman Sen; Ugur Sen; Cuma Bindal

2006-01-01

62

Residual stresses in LENS-deposited AISI 410 stainless steel plates  

Microsoft Academic Search

The residual stress in thin plate components deposited by the laser engineered net shaping (LENS®) process was investigated experimentally and numerically. Neutron diffraction mapping was used to characterize the residual stress in LENS-deposited AISI 410 stainless steel thin wall plates. Using the commercial welding software SYSWELD, a thermo-mechanical three-dimensional finite element model was developed, which considers also the effect of

Liang Wang; Sergio D. Felicelli; Phillip Pratt

2008-01-01

63

Corrosion protection of AISI 316 stainless steel by ALD alumina\\/titania nanometric coatings  

Microsoft Academic Search

Stainless steels are used today in a wide range of applications as a result of their combination of high corrosion resistance\\u000a and good mechanical properties. In some applications, for example, temporary contact biomedical devices or solar water heaters,\\u000a corrosion resistance may need further improvement, and surface coatings may be applied for enhanced protection. In this study,\\u000a AISI 316 stainless steel

E. Marin; A. Lanzutti; L. Guzman; L. Fedrizzi

64

Plasma nitriding of AISI 52100 ball bearing steel and effect of heat treatment on nitrided layer  

Microsoft Academic Search

.  In this paper an effort has been made to plasma nitride the ball bearing steel AISI 52100. The difficulty with this specific\\u000a steel is that its tempering temperature (~170–200°C) is much lower than the standard processing temperature (~460–580°C) needed\\u000a for the plasma nitriding treatment. To understand the mechanism, effect of heat treatment on the nitrided layer steel is investigated.\\u000a Experiments

RAVINDRA KUMAR; J ALPHONSA; RAM PRAKASH; K S BOOB; J GHANSHYAM; P A RAYJADA; P M RAOLE; S MUKHERJEE

65

Sensitization resistance of friction stir welded AISI 409 M grade ferritic stainless steel joints  

Microsoft Academic Search

Friction stir welded low chromium AISI 409 M ferritic stainless steel was investigated for susceptibility to intergranular\\u000a corrosion by oxalic and double-loop electrochemical potentiodynamic reactivation tests, and the degree of sensitization were\\u000a evaluated by the ratio of the reactivating and activating currents. Stir zone of friction stir welded joint exhibited smaller\\u000a degree of sensitization compared to the base metal and it

A. K. Lakshminarayanan; V. Balasubramanian

66

Corrosion behaviour of AISI 304 stainless steel with Cu coatings in H 2SO 4  

Microsoft Academic Search

The work addresses the influence of cementation and electrodeposition of copper coatings on the corrosion resistance of AISI 304 stainless steel immersed in 30wt.% H2SO4 at temperatures of 25 and 50°C. Corrosion process was evaluated by gravimetric tests, DC measurements and electrochemical impedance spectroscopy (EIS). The specimen surfaces were analysed by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and X-ray

A. Pardo; M. C. Merino; A. E. Coy; R. Arrabal; F. Viejo; A. M’hich

2007-01-01

67

Competing damage mechanisms in the thermo-mechanical fatigue of AISI 304L stainless steel  

Microsoft Academic Search

Thermo-mechanical fatigue (TMF) in AISI 304L stainless steel is investigated in two temperature ranges using four phase differences between the mechanical loading and the temperature. In the temperature range from 450°C to 700°C, the fatigue life was lowest in the in-phase condition. However, in the temperature range from 400°C to 650°C, the minimum fatigue life occurs in the counter-clockwise-diamond condition.

Keun-Ho Bae; Hyun-Ho Kim; Soon-Bok Lee

2011-01-01

68

Investigation on hot deformation behavior of AISI T1 high-speed steel  

Microsoft Academic Search

The hot deformation behavior of AISI T1 (18W–4Cr–1V) high-speed steel has been investigated in the temperature range 950–1150°C at strain rates of 0.001–10 s?1 and true strains of 0–0.6. The results show that the activation energy for deformation, Q, decreases with the increase of strain below 1000°C, and it changes slightly with the strain above 1000°C. Metallography shows that there

Jiantao Liu; Hongbing Chang; Ruiheng Wu; T. Y Hsu; Xueyu Ruan

2000-01-01

69

Hot workability of spray-formed AISI M3:2 high-speed steel  

Microsoft Academic Search

Axisymmetric hot compression tests (900–1100°C) on spray-formed AISI M3:2 high-speed steel were performed in order to establish suitable parameters for hot forging of this material. Special attention was paid to establish the deformation conditions that lead to the breakdown of the carbide network, present after spray forming, and to avoid fracture of the material as a result of deformation. By

C. Rodenburg; M. Krzyzanowski; J. H. Beynon; W. M. Rainforth

2004-01-01

70

Effects of yttrium and erbium ion implantation on the AISI 304 stainless steel passive layer  

Microsoft Academic Search

In this work, the response of AISI 304 stainless steel after having been implanted with 1017 ions\\/cm2 doses of Y and Er at an acceleration potential of 150 keV is examined. Computational estimates of the implanted profile have been performed using the PROFILE code. The nature of the outermost surface of the steel, i.e. the passive layer and onwards is

F. Pedraza; E Román; M. J Cristóbal; M. P Hierro; F. J Pérez

2002-01-01

71

Microstructure and Wear Behavior of TIG Surface-Alloyed AISI 4140 Steel  

Microsoft Academic Search

In this study, AISI 4140 steel surfaces were alloyed with preplaced SiC\\/C powders using a tungsten–inert gas (TIG) heat source. The effects of different production parameters on the microstructure, hardness, and wear resistance of the alloyed surfaces were investigated. Following the surface alloying, conventional characterization techniques such as optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and

MUSTAFA ULUTAN; M. MUSTAFA YILDIRIM; SONER BUYTOZ; OSMAN N. ÇELIK

2010-01-01

72

The effects of cold working on sensitization and intergranular corrosion behavior of AISI 304 stainless steel  

Microsoft Academic Search

The effects of prior cold rolling of up to an 80 pct reduction in thickness on the sensitization-desensitization behavior\\u000a of Type AISI 304 stainless steel and its susceptibility to intergranular corrosion have been studied by electrochemical potentiokinetic\\u000a reactivation (EPR) and Strauss-test methods. The results indicate that the prior deformation accelerated the sensitization\\u000a as compared to the undeformed stainless steel. The

Raghuvir Singh; I. Chattoraj; A. Kumar; B. Ravikumar; P. K. Dey

2003-01-01

73

Gas tungsten arc and shielded metal arc welding of AISI 41XX steels. Welding procedure specification  

SciTech Connect

Procedure WPS-127 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc and shielded metal arc welding of AISI 4130 and 4142 steels (ASTM A519) (P-No: None), 0.438-in. wall pipe; filler metal is AMS 6457, Class 4130 MC (F-, A-No; None) (GTAW) and E8018-B2L (F-4, A-3) (GMAW); shielding gas is argon (GTAW).

Wodtke, C.H.; Frizzell, D.R.

1985-08-01

74

Gas tungsten arc and shielded metal arc welding of AISI 41XX steels. Welding procedure specification  

Microsoft Academic Search

Procedure WPS-127 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc and shielded metal arc welding of AISI 4130 and 4142 steels (ASTM A519) (P-No: None), 0.438-in. wall pipe; filler metal is AMS 6457, Class 4130 MC (F-, A-No; None) (GTAW) and E8018-B2L (F-4, A-3) (GMAW); shielding gas is argon (GTAW).

C. H. Wodtke; D. R. Frizzell

1985-01-01

75

Microstructural development and cracking behavior of AISI 304 stainless steel tested in time dependent fatigue modes  

Microsoft Academic Search

Transmission and scanning electron microscopy were used to study the substructural development, crack initiation and crack propagation of AISI 304 stainless steel tested in low-cycle fatigue with various hold times. Tests at 593°C, a strain rate of 4 E-03 s⁻¹ and strain ranges of 0.5, 1.0 and 2.0 percent were interrupted at various fractions of the fatigue life, both during

A. M. Ermi; J. Moteff

1983-01-01

76

Correlation of substructure with time-dependent fatigue properties of aisi304 stainless steel  

Microsoft Academic Search

Transmission electron microscopy was employed to study the substructure of AISI 304 stainless steel tested at 482, 593, and\\u000a 650 C in low-cycle fatigue with various hold times. Total strains investigated ranged from 0.5 to 2.0 pct, strain rates of\\u000a 4 E-03 and 4 E-05 s-1. The cell size was found to be inversely related to the relaxed tensile saturation

A. M. Ermi; John Moteff

1982-01-01

77

The effect of intercritical heat treatment on the mechanical properties of AISI 3115 steel  

Microsoft Academic Search

This paper presents the effect of intercritical heat treatment (IHT) on the mechanical properties of AISI 3115 alloy steel. The steel was intercritically heat-treated at a temperature range of 730–830°C followed by water quenching. The properties of tensile strength, fatigue, hardness and microstructure were evaluated from the mechanical tests and metallographic analysis, respectively. The experimental results showed that tensile strength

M. A. Maleque; Y. M. Poon; H. H. Masjuki

2004-01-01

78

Influence of material microstructure changes on surface integrity in hard machining of AISI 52100 steel  

Microsoft Academic Search

Residual stresses are a consequence of thermo-mechanical and microstructural phenomena generated during the machining operation.\\u000a Therefore, for improving product performance in machined hardened steels, material microstructure changes (commonly referred\\u000a to as white and dark layers) must be taken into account. This paper presents a finite element model for white and dark layers\\u000a formation in orthogonal machining of hardened AISI 52100

Domenico Umbrello

2011-01-01

79

Effects of process parameters on microstructural evolution during hot ring rolling of AISI 5140 steel  

Microsoft Academic Search

Metal undergoes complicated microstructural evolution during hot ring rolling (HRR), which determines the quality, mechanical properties and life span of the ring formed. In this paper, a three-dimensional rigid–plastic and coupled thermomechanical finite element model for HRR was developed and combined with a microstructural evolution model of AISI 5140 steel, on the basis of a DEFORM 3D software platform. The

Sun Zhichao; Yang He; Ou Xinzhe

2010-01-01

80

Planning for the 400,000 tons/year AISI ironmaking demonstration plant  

SciTech Connect

The American Iron and Steel Institute (AISI) has formulated a four-year program to design, construct, and operate a 400,000 net ton per year ironmaking demonstration plant. The plant will employ the coal-based ironmaking process developed under a 1989 cooperative agreement with DOE. AISI will manage the design and construction to be completed in the first two years and operate the plant for the second two years with a variety or ores, coals, and fluxes. Campaigns of increasing length are planned to optimize operations. After successful operation, the plant will be taken over by the host company. Results of studies to date indicate that, on a commercial scale, the AISI process will use 27% less energy and have variable operating costs $10 per ton lower and capital costs of $160 per annual ton, compared to the $250 per annual ton rebuild cost for the coke oven-blast furnace process it will replace. The process will enable the domestic steel industry to become more competitive by reducing its capital and operating cost. Furthermore, by eliminating the pollution problems associated with coke production and by completely enclosing the smelting reactions, this process represents a major step towards an environmentally friendly steel industry.

Aukrust, E. (LTV Steel Corp., Cleveland, OH (United States). AISI Direct Steelmaking Program)

1993-01-01

81

Endurance and failure characteristics of modified Vasco X-2, CBS 600 and AISI 9310 spur gears. [aircraft construction materials  

NASA Technical Reports Server (NTRS)

Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential of tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears.

Townsend, D. P.; Zaretsky, E. V.

1980-01-01

82

NANOTUBOS DE CARBONO COM DUAS-CAMADAS USANDO UMA FORMULAÇÃO NÃO-LOCAL E A RESPOSTA IMPULSO  

Microsoft Academic Search

Neste trabalho, o modelo de Euler-Bernoulli para vigas é estendido para incluir o efeito elástico não local para nano tu- bos de carbono com duas-camadas, (DWNTs). Também é considerado o efeito das forças de interações elásticas de van der Walls. O problema de autovalor acoplado é formulado em termos de uma base composta pela solução fundamental de uma equação diferencial

Rosemaira Dalcin Copetti; Julio R. Claeyssen; Teresa Tsukazan

2008-01-01

83

Corrosion-wear monitoring of TiN coated AISI 316 stainless steel by electrochemical noise measurements  

NASA Astrophysics Data System (ADS)

A modified electrochemical noise (EN) technique has been applied to monitor corrosion-wear of TiN coated AISI 316 stainless steel sliding against corundum in 0.5 M H 2SO 4. Experimental results show that the EN technique can sensitively detect potential and current variations during a corrosion-wear process. Corrosion-wear mechanisms of TiN coatings depend on their substrate properties. When the substrate is passive, such as AISI 316 stainless steel, the potential and current variations reflect the properties of coatings. Depassivation and repassivation alternately take place on the tribo-activated wear area during the steady-state phase.

Quan, Zhenlan; Wu, Pei-Qiang; Tang, Lin; Celis, J.-P.

2006-11-01

84

Wear behavior of AISI 1090 steel modified by pulse plasma technique  

NASA Astrophysics Data System (ADS)

AISI 1090 steel was pulse plasma treated (PPT) using a Molybdenum electrode. Two different pulse numbers were chosen to obtain modified layers of 20±5 ?m thickness. The dry sliding wear studies performed on this steel with and without PPT against an alumina ball counterpart showed that the PPT improved the wear resistance. The pulse number of the PPT modified layer was found to be highly influential in imparting the wear resistance to this steel, due to enhancement of surface hardness depending on treatment time.

Ayday, Aysun; Durman, Mehmet

2012-09-01

85

Study of passive films formed on AISI 304 stainless steel by impedance measurements and photoelectrochemistry  

SciTech Connect

Moss-Schottky plots and photoelectrochemical measurements were made on films formed at different potentials on AISI 304 stainless steel in a borate/boric acid solution, pH 9.2. The results allowed the determination of the semiconductive properties and band structure of the films, which account for the existence of two kinds of films depending on the formation potential. For potentials below 0 V (SCE), the results point out for a film with an inverse spinel structure constituted by Cr-substituted magnetite with two donor levels. Above 0 V only one donor level is detected, which should be Fe{sup 2 +} on tetrahedral sites.

Simoes, A.M.P.; Ferreiro, M.G.S. (Dept. de Engenharia Quimica, Instituto Superior Tecnico, 1096 Lisboa Codex (PT)); Rondot, B.; Belo, M. (Centre National de la Recherche Scientifique, 94 - Vitry-sur-Seine (France). Centre d'Etudes de Chimie Metallurgique)

1990-01-01

86

Experimental and Analytical Load-Life Relation for AISI 9310 Steel Spur Gears  

NASA Technical Reports Server (NTRS)

Life tests were conducted at three different loads with three groups of 8.9 cm pitch diameter spur gears made of vacuum arc remelted VAR AISI 9310 steel. Life was found to vary inversely with load to the 4.3 and 5.1 power at the L10 sub and L50 sub life levels, respectively. The Weibull slope varied linearly with maximum Hertz contact stress, having an average value of 2.5. The test data when compared to AGMA standards showed a steeper slope for the load-life diagram.

Townsend, D. P.; Coy, J. J.; Zaretsky, E. V.

1977-01-01

87

Plasma characteristics of PTFE and hexafluoropropene deposition on AISI 1050 Stainless steel for lubrication  

NASA Astrophysics Data System (ADS)

Optical and electrical characteristics of sprayed polytetrafluoroethylene (PTFE) by Argon plasma and also hexafluoropropene (C3F6) plasma were measured for different plasma parameters (treatment time, type of gas, power, pressure, electrode distance). The coated thin film onto AISI 1050 stainless steel characteristics were also investigated. After the deposition, surface morphology was analysed by Scaning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), Atomic force microscope (AFM). Abrasion of samples was tested. As a result of abrasion test the PTFE plasma processes more effective than C3F6 coating. This Work has been supported by TUBITAK TEYDEB project no:9100036

Teke, Erdogan; Bozduman, Ferhat; Gulec, Ali; Varol, Hatice; Manolache, Sorin; Camurlu, Erdem; Kurbanoglu, Cahit; Oksuz, Lutfi

2012-10-01

88

Rolling-contact fatigue lives of steel AISI 52100 balls with eight mineral and synthetic lubricants  

Microsoft Academic Search

This work has evaluated the rolling-contact fatigue lives of AISI 52100 steel balls with several mineral and synthetic oils with and without additive using a four-ball tester. The studied lubricants include S.N.-350 (mineral oil), S.N.-600 (mineral oil), TMP-05 (synthetic polyol ester), TMP-05 + 2%ZnDDP, P.A.G.-9 (synthetic polyalkyl glycol), P.A.G.-12 (synthetic polyalkyl glycol) and Breox-B-135X (synthetic polyalkyl glycol). Weibull plots and

Yinglong Wang; J. E. Fernandez; D. G. Cuervo

1996-01-01

89

Wear behavior of AISI 1090 steel modified by pulse plasma technique  

SciTech Connect

AISI 1090 steel was pulse plasma treated (PPT) using a Molybdenum electrode. Two different pulse numbers were chosen to obtain modified layers of 20{+-}5 {mu}m thickness. The dry sliding wear studies performed on this steel with and without PPT against an alumina ball counterpart showed that the PPT improved the wear resistance. The pulse number of the PPT modified layer was found to be highly influential in imparting the wear resistance to this steel, due to enhancement of surface hardness depending on treatment time.

Ayday, Aysun; Durman, Mehmet [Sakarya University, Faculty of Engineering, Department of Metallurgical and Materials Engineering, Adapazar Latin-Small-Letter-Dotless-I , 54187 (Turkey)

2012-09-06

90

Study of Carbide Evolution During Thermo-Mechanical Processing of AISI D2 Tool Steel  

NASA Astrophysics Data System (ADS)

The microstructure of a cold-worked tool steel (AISI D2) with various thermo-mechanical treatments was examined in the current study to identify the effects of these treatments on phases. X-ray diffraction was used to identify phases. Microstructural changes such as spheroidization and coarsening of carbides were studied. Thermodynamic calculations were used to verify the results of the differential thermal analysis. It was found that soaking temperature and time have a large influence on dissolution, precipitation, spheroidization, and coalescence of carbides present in the steel. This consequently influences the hot workability and final properties.

Bombac, D.; Fazarinc, M.; Podder, A. Saha; Kugler, G.

2013-03-01

91

Effect of mechanical activation on jell boronizing treatment of the AISI 4140  

NASA Astrophysics Data System (ADS)

The article presents the effect of mechanical activation on the growth kinetics of boride layer of boronized AISI 4140 steel. The samples were boronized by ferroboron + (SiO2-Na2O) powders for 873-1173 K temperature and 2, 4, 6 and 8 h times, respectively. The morphology and types of borides formed on the surface of AISI 4140 steel substrate were analyzed. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as function of treatment time and temperature in the range of 873-1173 K. High diffusivity was obtained by creating a large number of defects through mechanical activation in the form of nanometer sized crystalline particles through the repeated fracturing and cold-welding of the powder particles, and a depth of 100 ?m was found in the specimen borided by the 2 h MA powders, for 4 h and 1073 K, where 2000-2350 HV were measured. Consequently, the application conditions of boronizing were improved by usage of mechanical activation. The preferred Fe2B boride without FeB could be formed in the boride layer under 973 K boronizing temperature by mechanically activated by ferroboron + sodium silicate powder mixture due to the decrease of the activation energy.

Y?lmaz, S. O.; Karata?, S.

2013-06-01

92

Determination of Proper Austenitization Temperatures for Hot Stamping of AISI 4140 Steel  

NASA Astrophysics Data System (ADS)

High strength steels are desirable materials for use in automobile bodies in order to reduce vehicle weight and increase the safety of car passengers, but steel grades with high strength commonly show poor formability. Recently, steels with controlled microstructures and compositions are used to gain adequate strength after hot stamping while maintaining good formability during processing. In this study, microstructure evolutions and changes in mechanical properties of AISI 4140 steel sheets resulting from the hot stamping process at different austenitization temperatures were investigated. To determine the proper austenitization temperatures, the results were compared with those of the cold-worked and cold-worked plus quench-tempered specimens. Comparisons showed that the austenitization temperatures of 1000 and 1100 °C are proper for hot stamping of 3-mm-thick AISI 4140 steel sheets due to the resultant martensitic microstructure which led to the yield and ultimate tensile strength of 1.3 and 2.1 GPa, respectively. Such conditions resulted in more favorable simultaneous strength and elongation than those of hot-stamped conventional boron steels.

Samadian, Pedram; Parsa, Mohammad Habibi; Shakeri, Amid

2014-04-01

93

Effects of processing on the transverse fatigue properties of low-sulfur AISI 4140 steel  

SciTech Connect

The effects of inclusions due to steelmaking processes on the fatigue life of AISI 4140 have been investigated. The test matrix consisted of three commercially produced heats of AISI 4140 of comparable cleanliness: one was conventionally cast (CC), and two were inert gas-shielded/bottom-poured (IGS). One of the IGS heats was calcium-treated to explore the effects of inclusion shape control (IGS/SC). All heats were hot-rolled and reduced over 95 pct to produce bar stock of 127 to 152 mm (5 to 6 in.) in diameter. Transverse axial specimens confirming to ASTM E466 were machined, quenched, and tempered to approximately 40 HRC, and they were fatigue tested in tension-tension cycling (R = 0.1). Test results and statistical analyses of the stress-life data show that the IGS grade has several times the fatigue strength of the CC grade at 10{sup 7} cycles. Lower-limit fatigue strengths calculated at a 99.9 pct probability were 518.5 MPa (75.2 ksi) for IGS vs 55.6 MPa (8.1 ksi) for the CC grade. The IGS/SC grad had the best performance at all stress and life levels. The results obtained indicate that fatigue performance can be improved by choosing a processing method that reduces the indigence of exogenous oxides and by controlling the shape of the sulfides.

Collins, S.R.; Michal, G.M. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering

1993-12-01

94

Surface Treatments for Improved Performance of Spinel-coated AISI 441 Ferritic Stainless Steel  

SciTech Connect

Ferritic stainless steels are promising candidates for IT-SOFC interconnect applications due to their low cost and resistance to oxidation at SOFC operating temperatures. However, steel candidates face several challenges; including long term oxidation under interconnect exposure conditions, which can lead to increased electrical resistance, surface instability, and poisoning of cathodes due to volatilization of Cr. To potentially extend interconnect lifetime and improve performance, a variety of surface treatments were performed on AISI 441 ferritic stainless steel coupons prior to application of a protective spinel coating. The coated coupons were then subjected to oxidation testing at 800 and 850°C in air, and electrical testing at 800°C in air. While all of the surface-treatments resulted in improved surface stability (i.e., increased spallation resistance) compared to untreated AISI 441, the greatest degree of improvement (through 20,000 hours of testing at 800°C and 14,000 hours of testing at 850°C) was achieved by surface blasting.

Stevenson, Jeffry W.; Riel, Eric M.; Stephens, Elizabeth V.; Khaleel, Mohammad A.

2013-01-01

95

Microstructure, Texture, and Mechanical Property Analysis of Gas Metal Arc Welded AISI 304 Austenitic Stainless Steel  

NASA Astrophysics Data System (ADS)

The present study elaborately explains the effect of welding parameters on the microstructure, texture, and mechanical properties of gas metal arc welded AISI 304 austenitic stainless steel sheet (as received) of 4 mm thickness. The welded joints were prepared by varying welding speed (WS) and current simultaneously at a fixed heat input level using a 1.2-mm-diameter austenitic filler metal (AISI 316L). The overall purpose of this study is to investigate the effect of the variation of welding conditions on: (i) Microstructural constituents using optical microscope and transmission electron microscope; (ii) Micro-texture evolution, misorientation distributions, and grain boundaries at welded regions by measuring the orientation data from electron back scattered diffraction; and (iii) Mechanical properties such as hardness and tensile strength, and their correlation with the microstructure and texture. It has been observed that the higher WS along with the higher welding current (weld metal W1) can enhance weld metal mechanical properties through alternation in microstructure and texture of the weld metal. Higher ?-ferrite formation and high-angle boundaries along with the <101> + <001> grain growth direction of the weld metal W1 were responsible for dislocation pile-ups, SFs, deformation twinning, and the induced martensite with consequent strain hardening during tensile deformation. Also, fusion boundary being the weakest link in the welded structure, failure took place mainly at this region.

Saha, Saptarshi; Mukherjee, Manidipto; Pal, Tapan Kumar

2014-12-01

96

Effects of biofilm formation on the electrochemical behavior of AISI 304 SS in board machine environment  

SciTech Connect

The electrochemical behavior of and biofilm formation on AISI 304 stainless steel were studied in board machine environment with natural bacteria population. Open circuit potentials, redox-potential as well as different electrochemical measurements were performed. The biofilms formed were analyzed by microbial cultivation and by epifluorescence microscopy. The results of the measurements were compared with those performed both in sterilized white water and in artificial white water. The anodic polarization behavior of just immersed specimens was very similar in biotic (real), artificial and abiotic (sterilized) white water. Pitting initiated at very low potentials and continued to very negative values. The initiation of pitting became more difficult when the immersion time increased to 7 or 8 days in real, artificial or sterilized water. When the immersion time further increased, the pitting nucleated more easily in sterilized white water as well as in artificial white water than in biotic white water. In the laboratory equipment it was possible to maintain the biofilm already formed in the board mill, but the amount of sulfate reducing bacteria decreased and the amount of biofilm did not further increase. The composition and structure of the biofilm formed in laboratory differed from that formed in board mill conditions. The preliminary results indicate that the formation of biofilm in biotic white water rather inhibits than enhances the pitting corrosion of type AISI 304 stainless steel.

Carp, L.; Hakkarainen, T. [VTT Manufacturing Technology (Finland); Raaska, L. [VTT Biotechnology and Food Research (Finland)

1999-11-01

97

Microstructure, Texture, and Mechanical Property Analysis of Gas Metal Arc Welded AISI 304 Austenitic Stainless Steel  

NASA Astrophysics Data System (ADS)

The present study elaborately explains the effect of welding parameters on the microstructure, texture, and mechanical properties of gas metal arc welded AISI 304 austenitic stainless steel sheet (as received) of 4 mm thickness. The welded joints were prepared by varying welding speed (WS) and current simultaneously at a fixed heat input level using a 1.2-mm-diameter austenitic filler metal (AISI 316L). The overall purpose of this study is to investigate the effect of the variation of welding conditions on: (i) Microstructural constituents using optical microscope and transmission electron microscope; (ii) Micro-texture evolution, misorientation distributions, and grain boundaries at welded regions by measuring the orientation data from electron back scattered diffraction; and (iii) Mechanical properties such as hardness and tensile strength, and their correlation with the microstructure and texture. It has been observed that the higher WS along with the higher welding current (weld metal W1) can enhance weld metal mechanical properties through alternation in microstructure and texture of the weld metal. Higher ?-ferrite formation and high-angle boundaries along with the <101> + <001> grain growth direction of the weld metal W1 were responsible for dislocation pile-ups, SFs, deformation twinning, and the induced martensite with consequent strain hardening during tensile deformation. Also, fusion boundary being the weakest link in the welded structure, failure took place mainly at this region.

Saha, Saptarshi; Mukherjee, Manidipto; Pal, Tapan Kumar

2015-03-01

98

Welding procedure specification. Supplement 1. Records of procedure qualification tests. Shielded metal arc welding of AISI 4340 alloy steel  

Microsoft Academic Search

Procedure WPS-115 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for shielded metal arc welding of AISI 4340 alloy steel, in thickness range 0.187 to 2.0 inch; filler metal is E7018 (F-4, A-1).

C. H. Wodtke; D. R. Frizzell; W. A. Plunkett

1986-01-01

99

Enhancement of corrosion resistance of AISI 420 stainless steels by nitrogen and silicon plasma immersion ion implantation  

Microsoft Academic Search

The effects of nitrogen and silicon plasma immersion ion implantation (PIII) on the surface corrosion resistance of martensitic stainless steel AISI 420 were investigated. Nitrogen was plasma-implanted at elevated temperature and diffused to form a thick and continuous nitrided surface layer, followed by silicon cathodic arc plasma implantation to produce an additional Si-rich oxynitride region near the stainless steel surface.

Ricky K. Y. Fu; D. L. Tang; G. J. Wan; Paul K. Chu

2007-01-01

100

Prediction of phase transformations during laser surface hardening of AISI 4140 including the effects of inhomogeneous austenite formation  

Microsoft Academic Search

Modelling of laser surface hardening of AISI 4140 steel including the effect of inhomogeneous austenite formation due to locally different austenizing and quenching conditions is carried out to gain a better understanding of the material reaction during short-time hardening processes. Dilatometric studies at high heating and cooling rates lead to base informations for material laws reflecting the influence of the

T. Miokovi?; V. Schulze; O. Vöhringer; D. Löhe

2006-01-01

101

Sintering and Mechanical Properties of AISI M2 High-Speed Steel Powder Molded at Low Pressures  

Microsoft Academic Search

Low compaction pressures of powders result in low die wear, less power consumption and high production rate. The present study aims to investigate compaction, vacuum sintering, and mechanical behavior of AISI M2 high speed steel (HSS) powder cold molded at relatively low pressures (98–392 Mpa). It was found that sintered density rised with compaction pressure, time, and temperature. Full density was

S. Eroglu

2010-01-01

102

Surface fatigue life and failure characteristics of EX-53, CBS 1000M, and AISI 9310 gear materials  

NASA Technical Reports Server (NTRS)

Spur gear endurance tests and rolling-element surface fatigue tests are conducted to investigate EX-53 and CBS 1000M steels for use as advanced application gear materials, to determine their endurance characteristics, and to compare the results with the standard AISI 9310 gear material. The gear pitch diameter is 8.89 cm (3.50 in). Gear test conditions are an oil inlet temperature of 320 K (116 F), an oil outlet temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench-type rolling-element fatigue tests are conducted at ambient temperature with a bar specimen speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa (700 ksi). The EX-53 test gears have a surface fatigue life of twice that of the AISI 9310 spur gears. The CBS 1000M test gears have a surface fatigue life of more than twice that of the AISI 9310 spur gears. However, the CBS 1000M gears experience a 30-percent tooth fracture failure which limits its use as a gear material. The rolling-contact fatigue lines of RC bar specimens of EX-53 and ASISI 9310 are approximately equal. However, the CBS 1000M RC specimens have a surface fatigue life of about 50 percent that of the AISI 9310.

Townsend, D. P.

1985-01-01

103

Microstructure and corrosion behavior of the AISI 304 stainless steel after Nd:YAG pulsed laser surface melting  

Microsoft Academic Search

Different laser energy densities were utilized to treat AISI 304 stainless steel via Nd:YAG pulsed laser surface melting (LSM). The surface composition and microstructure of the stainless steel were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). In particular, the corrosion behaviors of the stainless steel surface without and with LSM were

C. Y. Cui; X. G. Cui; Y. K. Zhang; Q. Zhao; J. Z. Lu; J. D. Hu; Y. M. Wang

2011-01-01

104

Cyclic deformation and near surface microstructures of shot peened or deep rolled austenitic stainless steel AISI 304  

Microsoft Academic Search

Cylindrical specimens of the austenitic stainless steel AISI 304 were shot peened or deep rolled with different peening intensities, and rolling pressures, respectively. The resulting near surface properties were characterized by cross sectioning transmission electron microscopy (TEM), residual stress and phase analysis as well as interference line half-width and microhardness measurements. Cyclic deformation curves were obtained by hysteresis measurements under

I Altenberger; B Scholtes; U Martin; H Oettel

1999-01-01

105

Ultrasonic fatigue tests on bearing steel AISI-SAE 52100 at frequency of 20 and 30 kHz  

Microsoft Academic Search

Due to the increasing requirements in the market, engine components must have also an increasing life, which involves an improvement over 109 cycles in the fatigue strength of bearing steels, and sometimes even more. In order to achieve this improvement, this paper proposes a study of the fatigue behavior of the AISI-SAE 52100 between 105 and 1011 cycles.Most fatigue life

I. Marines; G. Dominguez; G. Baudry; J.-F. Vittori; S. Rathery; J.-P. Doucet; C. Bathias

2003-01-01

106

Effect of electrical discharge machining on surface characteristics and machining damage of AISI D2 tool steel  

Microsoft Academic Search

In this work the electrical discharge machining (EDM) of AISI D2 tool steel was investigated. The surface characteristics and machining damage caused by EDM were studied in terms of machining parameters. Based on the experimental data, an empirical model of the tool steel was also proposed. A new damage variable was used to study the EDM damage. The workpiece surface

Y. H. Guu; H. Hocheng; C. Y. Chou; C. S. Deng

2003-01-01

107

Tensile and fatigue data for irradiated and unirradiated AISI 310 stainless steel and titanium - 5 percent aluminum - 2.5 percent tin: Application of the method of universal slopes  

NASA Technical Reports Server (NTRS)

Irradiated and unirradiated tensile and fatigue specimens of AISI 310 stainless steel and Ti-5Al-2.5Sn were tested in the range of 100 to 10,000 cycles to failure to determine the applicability of the method of universal slopes to irradiated materials. Tensile data for both materials showed a decrease in ductility and increase in ultimate tensile strength due to irradiation. Irradiation caused a maximum change in fatigue life of only 15 to 20 percent for both materials. The method of universal slopes predicted all the fatigue data for the 310 SS (irradiated as well as unirradiated) within a life factor of 2. For the titanium alloy, 95 percent of the data was predicted within a life factor of 3.

Debogdan, C. E.

1973-01-01

108

Study of ageing-induced ??-martensite formation in cold-worked AISI type 304 stainless steel using an acoustic emission technique  

Microsoft Academic Search

a'-martensite formation during cooling of cold-worked and aged AISI type 304 stainless steel has been studied by an acoustic emission technique. The ageing was carried out at 673 K for 1 h. A substantial amount of acoustic emission generated during cooling of cold-worked and aged AISI 304 stainless steel specimens compared to negligible acoustic emission observed during cooling (after ageing)

C. K. Mukhopadhyay; T. Jayakumar; K. V. Kasiviswanathan; Baldev Raj

1995-01-01

109

Ultrasonic and metallographic studies on AISI 4140 steel exposed to hydrogen at high pressure and temperature  

NASA Astrophysics Data System (ADS)

This thesis conducts an investigation to study the effects of hydrogen exposure at high temperature and pressure on the behavior of AISI 4140 steel. Piezoelectric ultrasonic technique was primarily used to evaluate surface longitudinal wave velocity and defect geometry variations, as related to time after exposure to hydrogen at high temperature and pressure. Critically refracted longitudinal wave technique was used for the former and pulse-echo technique for the latter. Optical microscopy and scanning electron microscopy were used to correlate the ultrasonic results with the microstructure of the steel and to provide better insight into the steel behavior. The results of the investigation indicate that frequency analysis of the defect echo, determined using the pulse-echo technique at regular intervals of time, appears to be a promising tool for monitoring defect growth induced by a high temperature and high pressure hydrogen-related attack.

Oruganti, Malavika

110

Study of the Sensitization on the Grain Boundary in Austenitic Stainless Steel Aisi 316  

NASA Astrophysics Data System (ADS)

Intergranular corrosion (IGC) is one of the major problems in austenitic stainless steels. This type of corrosion is caused by precipitation of secondary phases on grain boundaries (GB). Precipitation of the secondary phases can lead to formation of chromium depleted zones in the vicinity of grain boundaries. Mount of the sensitization of material is characterized by the degree of sensitization (DOS). Austenitic stainless steel AISI 316 as experimental material had been chosen. The samples for the study of sensitization were solution annealed on 1100 °C for 60 min followed by water quenching and then sensitization by isothermal annealing on 700 °C and 650 °C with holding time from 15 to 600 min. Transmission electron microscopy (TEM) was used for identification of secondary phases. Electron backscattered diffraction (EBSD) was applied for characterization of grain boundary structure as one of the factors which influences on DOS.

Kocsisová, Edina; Dománková, Mária; Slatkovský, Ivan; Sahul, Martin

2014-12-01

111

Effect of Starch Binders in Alumina Coatings on Aisi 316 L Stainless Steel for Medical Application  

NASA Astrophysics Data System (ADS)

A slurry immersion technique of alumina coatings was carried out on several AISI 316 L stainless steels using two types of binding agents; commercial starch and Sarawakian starch (sago), which were also mixed with polyvinylchloride (PVA) for strengthening purposes. The sintering temperatures in this work were varied from 500 to 1000°C. Prior to sintering process, all stainless steels were metallographically ground and polished to approximately 0.6 µm of average roughness. Detailed characterisations on the sintered specimens were carried out with the aid of the secondary electron microscopy (SEM), microhardness and a profilometer. The results revealed that coated steels using sago binder showed improved adhesion and homogenous microstructures with greater hardness of 2642 HV than those found in coated steel with commercial starch after sintering process.

Ghazali, M. J.; Pauzi, A. A.; Azhari, C. H.; Ghani, J. A.; Sulong, A. B.; Mustafa, R.

112

Microstructural characterization of the HAZ in AISI 444 ferritic stainless steel welds  

SciTech Connect

Ferritic stainless steel is used as a coating for equipment in the petroleum refining industry. Welding is the main manufacturing and maintenance process used. However, little information on the metallurgical alterations caused by welding of these steels is found in the literature, prompting this study. In this study the authors evaluated the HAZ microstructure of AISI 444 ferritic stainless steel welded plates, by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that a weld thermal cycle caused microphase precipitation in the HAZ of the ferritic stainless steel. Also needle-like Laves phase precipitation occurred in the HAZ, near the partially-melted zone. Other secondary phases such as chi and sigma were observed, as well as nitride, carbide and carbonitride precipitates.

Silva, Cleiton C. [Federal University of Ceara, Department of Materials and Metallurgical Engineering, Welding Engineering Laboratory, Campus do Pici, Building 715, CEP 60455-760, Fortaleza, Ceara (Brazil)], E-mail: cleitonufc@yahoo.com.br; Farias, Jesualdo P.; Miranda, Helio C.; Guimaraes, Rodrigo F. [Federal University of Ceara, Department of Materials and Metallurgical Engineering, Welding Engineering Laboratory, Campus do Pici, Building 715, CEP 60455-760, Fortaleza, Ceara (Brazil); Menezes, John W.A. [Federal University of Ceara, Department of Materials and Metallurgical Engineering, Materials Characterization Laboratory, Campus do Pici, Building 720, CEP 60455-760, Fortaleza, Ceara (Brazil); Neto, Moises A.M. [Federal University of Santa Catarina, Department of Mechanical Engineering, POLO-Laboratorios de Pesquisa em Refrigeracao e Termofisica, Florianopolis, Santa Catarina (Brazil)

2008-05-15

113

Residual Stresses in LENS-Deposited AISI 410 Stainless Steel Plates  

SciTech Connect

The residual stress in thin plate components deposited by the laser engineered net shaping (LENS{reg_sign}) process was investigated experimentally and numerically. Neutron diffraction mapping was used to characterize the residual stress in LENS-deposited AISI 410 stainless steel thin wall plates. Using the commercial welding software SYSWELD, a thermo-mechanical three-dimensional finite element model was developed, which considers also the effect of metallurgical phase transformations. The model was employed to predict the temperature history and the residual stress field during the LENS process. Several simulations were performed with the geometry and process parameters that were used to build the experimental samples. The origin of the residual stress distribution is discussed based on the thermal histories of the samples, and the modeling results are compared with measurements obtained by neutron diffraction mapping.

Wang, L [Mississippi State University (MSU); Felicellli, S D [Mississippi State University (MSU); Pratt, Phillip R [ORNL

2008-01-01

114

Pitting fatigue characteristics of AISI M-50 and super nitralloy spur gears  

NASA Technical Reports Server (NTRS)

Two groups of 3.50-in. pitch-diameter spur gears, without tip relief, made from consumable-electrode vacuum-melted (CVM) AISI M-50 steel and CVM super nitralloy (5Ni-2A1) were tested under conditions which produced fatigue pitting. The M-50 gears had fatigue lives approximately 50 percent longer than the super nitralloy gears. Both groups of gears failed by classical rolling-element fatigue at the pitch circle. When the gears were overrun past initial spall formation, the spalled M-50 gear teeth failed by fatigue fracture. The M-50 material had higher wear than the super nitralloy material. Differences in fatigue life and wear were not considered statistically significant.

Townsend, D. P.; Chevalier, J. L.; Zaretsky, E. V.

1973-01-01

115

The Effect of Carbon Dioxide and Nitrogen ion implantation of AISI 52100 Steel  

NASA Astrophysics Data System (ADS)

Ion implantation has been used to modify the mechanical properties of a wide range of metals and alloys using plasma techniques for ion sources and plasma surface treatment [1]. In this study AISI 52100 steel disks, containing 1.5 wt% Cr as the major alloying element, were implanted with nitrogen and carbon dioxide ions at the energy of 90 KeV, with dose in the range 1 × 1018 to 1 × 1019 N2+ ions cm-2, and 3 × 1018 to 1 × 1019 for co2+ ions cm-2. Ion beam current densities and sample temperature, during implantation were 3-6 ?A/cm2 and 170°C, respectively. Experiments show, hardness of sample, increases 30-49% using N2+ ions, and 5-17% using co2+ ions. In order to explain the results, formation of beta-CrN and carbide pahses have been carried out using X-ray diffraction technique.

Sari, Amir H.; Ghoranneviss, M.; Mardanian, M.; Hantehzadeh, M. R.; Hora, H.

2003-06-01

116

Effect of texture on corrosion behavior of AISI 304L stainless steel  

SciTech Connect

Electrochemical behavior of austenitic AISI 304 stainless steel in two different solutions is presented here. Effect of cold rolling conditions on corrosion behavior of the steel is studied with respect to strain-induced {alpha}'-martensite phase, residual stress, and texture of both the austenite and {alpha}'-martensite phases. The annealed steel plate has been unidirectionally cold, rolled-up to 90% reductions. X-ray diffraction (XRD) technique has been employed to quantify the volume fractions of austenite and martensite phases and to study the textural development in the steel in rolled conditions. The presence of close pack crystallographic planes parallel to the specimen surface found to improve the corrosion properties.

Ravi Kumar, B. [National Metallurgical Laboratory, Jamshedpur, 831007 Jharkhand (India)]. E-mail: ravik@nmlindia.org; Singh, Raghuvir [National Metallurgical Laboratory, Jamshedpur, 831007 Jharkhand (India); Mahato, Bhupeshwar [National Metallurgical Laboratory, Jamshedpur, 831007 Jharkhand (India); De, P.K. [National Metallurgical Laboratory, Jamshedpur, 831007 Jharkhand (India); Bandyopadhyay, N.R. [Bengal Engineering College, Howrah (India); Bhattacharya, D.K. [National Metallurgical Laboratory, Jamshedpur, 831007 Jharkhand (India)

2005-02-15

117

Characteristics of Laser Beam and Friction Stir Welded AISI 409M Ferritic Stainless Steel Joints  

NASA Astrophysics Data System (ADS)

This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded (solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints. Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains in the base material were changed to fine grains consisting duplex structure of ferrite and martensite due to the rapid cooling rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, columnar dendritic grain structure was observed in fusion zone of laser beam welded joints. Tensile testing indicates overmatching of the weld metal relative to the base metal irrespective of the welding processes used. The LBW joint exhibited superior impact toughness compared to the FSW joint.

Lakshminarayanan, A. K.; Balasubramanian, V.

2012-04-01

118

Microstructural characterization of laser surface melted AISI M2 tool steel.  

PubMed

We describe the microstructure of Nd:YAG continuous wave laser surface melted high-speed steel, namely AISI M2, treated with different laser scanning speeds and beam diameters on its surface. Microstructural characterization of the remelted surface layer was performed using light optical and scanning electron microscopy and X-ray diffraction. The combination of the three techniques provided new insights into the substantial changes induced by laser surface melting of the steel surface layer. The advantage of the method is that it avoids the difficult and tedious work of preparing samples of this hard material for transmission electron microscopy, which is the technique normally used to study these fine microstructures. A melted zone with a dendritic structure and a partially melted zone with a heterogeneous cellular structure were observed. M(2)C carbides with different morphologies were identified in the resolidified surface layer after laser melting. PMID:20701656

Arias, J; Cabeza, M; Castro, G; Feijoo, I; Merino, P; Pena, G

2010-09-01

119

Comparisons of modified Vasco X-2 and AISI 9310 gear steels  

NASA Technical Reports Server (NTRS)

Endurance tests were conducted with four groups of spur gears manufactured from three heats of consumable electrode vacuum melted (CVM) modified Vasco X-2. Endurance tests were also conducted with gears manufactured from CVM AISI 9310. Bench type rolling element fatigue tests were conducted with both materials. Hardness measurements were made to 811 K. There was no statistically significant life difference between the two materials. Life differences between the different heats of modified Vasco X-2 can be attributed to heat treat variation and resultant hardness. Carburization of gear flanks only can eliminate tooth fracture as a primary failure mode for modified Vasco X-2. However, a tooth surface fatigue spall can act as a nucleus of a tooth fracture failure for the modified Vasco X-2.

Townsend, D. P.; Zaretsky, E. V.

1980-01-01

120

Antibacterial properties and corrosion resistance of AISI 420 stainless steels implanted by silver and copper ions  

NASA Astrophysics Data System (ADS)

Silver or copper ions are often chosen as antibacterial agents. But a few reports are concerned with these two antibacterial agents for preparation of antibacterial stainless steel (SS). The antibacterial properties and corrosion resistance of AISI 420 stainless steel implanted by silver and copper ions were investigated. Due to the cooperative antibacterial effect of silver and copper ions, the Ag/Cu implanted SS showed excellent antibacterial activities against both Gram-negative Escherichia coli ( E. coli) and Gram-positive Staphylococcus aureus ( S. aureus) at a total implantation dose of 2×1017 ions/cm2. Electrochemical polarization curves revealed that the corrosion resistance of Ag/Cu implanted SS was slightly enhanced as compared with that of un-implanted SS. The implanted layer was characterized by X-ray photoelectron spectroscopy (XPS). Core level XPS spectra indicate that the implanted silver and copper ions exist in metallic state in the implanted layer.

Ni, Hong-wei; Zhang, Han-shuang; Chen, Rong-sheng; Zhan, Wei-ting; Huo, Kai-fu; Zuo, Zhen-yu

2012-04-01

121

Correlation of substructure with time-dependent fatigue properties of aisi304 stainless steel  

NASA Astrophysics Data System (ADS)

Transmission electron microscopy was employed to study the substructure of AISI 304 stainless steel tested at 482, 593, and 650 °C in low-cycle fatigue with various hold times. Total strains investigated ranged from 0.5 to 2.0 pct, strain rates of 4 E-03 and 4 E-05 s-1. The cell size was found to be inversely related to the relaxed tensile saturation stress, but with different constants of proportionality for the two strain rates. At the lower strain rate, substructures tended to resemble those produced by pure creep. A modified work-hardening theory was used to relate the peak saturation stress to both plastic strain and cell size.

Ermi, A. M.; Moteff, John

1982-09-01

122

Friction and wear of Synfluo 180XF wax and nano-Al 2O 3 filled Nomex fabric composites  

Microsoft Academic Search

Nomex fabric composites filled with the particulates of Synfluo 180XF wax (SFW) and nano-Al2O3 was prepared by dip-coating of Nomex fabric in a phenolic resin containing particulates to be incorporated and the successive curing. The friction and wear performance of the pure and filled Nomex fabric composites sliding against AISI-1045 steel in a pin-on-disk configuration were evaluated on a Xuanwu-III

Feng-Hua Su; Zhao-Zhu Zhang; Kun Wang; Wei-min Liu

2006-01-01

123

ALS Association  

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124

Modeling tool wear progression by using mixed effects modeling technique when end-milling AISI 4340 steel  

Microsoft Academic Search

Semi-dry and dry machining is being adopted by the metal cutting industry worldwide to reduce the harmful effects of traditional metal cutting fluids and the cost associated with procurement, use, and disposal of these fluids. This research focuses on end-milling of AISI 4340 steel with multi-layer physical vapor deposition (PVD) coated carbide inserts under semi-dry and dry cutting conditions and

Pinaki Chakraborty; Shihab Asfour; Sohyung Cho; Arzu Onar; Matthew Lynn

2008-01-01

125

Effect of postweld treatment on the fatigue crack growth rate of electron-beam-welded AISI 4130 steel  

Microsoft Academic Search

This article studies the effect ofin-chamber electron beam and ex-chamber furnace postweld treatments on the fatigue crack growth rate of electron-beam-welded\\u000a AISI 4130 steel. Mechanical properties of the weldment are evaluated by tensile testing, while the fatigue properties are\\u000a investigated by a fatigue crack propagation method. Microstructural examination shows that both postweld treatments temper\\u000a the weldment by the appropriate control

Chien-Chun Wang; Yih Chang

1996-01-01

126

Microstructure and Mechanical Properties of Laser Clad and Post-cladding Tempered AISI H13 Tool Steel  

NASA Astrophysics Data System (ADS)

This study reports a detailed investigation of the microstructure and mechanical properties (wear resistance and tensile strength) of hardened and tempered AISI H13 tool steel substrate following laser cladding with AISI H13 tool steel powder in as-clad and after post-cladding conventional bulk isothermal tempering [at 823 K (550 °C) for 2 hours] heat treatment. Laser cladding was carried out on AISI H13 tool steel substrate using a 6 kW continuous wave diode laser coupled with fiber delivering an energy density of 133 J/mm2 and equipped with a co-axial powder feeding nozzle capable of feeding powder at the rate of 13.3 × 10-3 g/mm2. Laser clad zone comprises martensite, retained austenite, and carbides, and measures an average hardness of 600 to 650 VHN. Subsequent isothermal tempering converted the microstructure into one with tempered martensite and uniform dispersion of carbides with a hardness of 550 to 650 VHN. Interestingly, laser cladding introduced residual compressive stress of 670 ± 15 MPa, which reduces to 580 ± 20 MPa following isothermal tempering. Micro-tensile testing with specimens machined from the clad zone across or transverse to cladding direction showed high strength but failure in brittle mode. On the other hand, similar testing with samples sectioned from the clad zone parallel or longitudinal to the direction of laser cladding prior to and after post-cladding tempering recorded lower strength but ductile failure with 4.7 and 8 pct elongation, respectively. Wear resistance of the laser surface clad and post-cladding tempered samples (evaluated by fretting wear testing) registered superior performance as compared to that of conventional hardened and tempered AISI H13 tool steel.

Telasang, Gururaj; Dutta Majumdar, Jyotsna; Wasekar, Nitin; Padmanabham, G.; Manna, Indranil

2015-02-01

127

Corrosion-wear monitoring of TiN coated AISI 316 stainless steel by electrochemical noise measurements  

Microsoft Academic Search

A modified electrochemical noise (EN) technique has been applied to monitor corrosion-wear of TiN coated AISI 316 stainless steel sliding against corundum in 0.5M H2SO4. Experimental results show that the EN technique can sensitively detect potential and current variations during a corrosion-wear process. Corrosion-wear mechanisms of TiN coatings depend on their substrate properties. When the substrate is passive, such as

Zhenlan Quan; Pei-Qiang Wu; Lin Tang; J.-P. Celis

2006-01-01

128

Formation of nanostructured surface layer on AISI 304 stainless steel by means of surface mechanical attrition treatment  

Microsoft Academic Search

A nanostructured surface layer was formed on an AISI 304 stainless steel with low stacking-fault energy by means of the surface mechanical attrition treatment (SMAT). The microstructure of the surface layer of the SMATed sample was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and cross-sectional TEM observation was performed to reveal the

H. W Zhang; Z. K Hei; G Liu; J Lu; K Lu

2003-01-01

129

Process parameters selection for laser polishing DF2 (AISI O1) by Nd:YAG pulsed laser using orthogonal design  

Microsoft Academic Search

Mechanisms of laser polishing metals in a continuous scanning mode, as envisaged and analyzed in this paper, are rather complex,\\u000a and experimental optimization of laser polishing metallic material is very time-consuming and difficult. Aiming at shortening\\u000a the experimental time in achieving a better surface finishing of DF2 (AISI 01) tool steel by pulse Nd:YAG laser, we used the\\u000a orthogonal experimental

Wei Guo; Meng Hua; Peter Wai-Tat Tse; Albert Chiu Kam Mok

130

Influence of chromium and cerium implantation in the electrochemical development of passive layers on AISI 304L  

Microsoft Academic Search

In this work X-ray photoelectron spectroscopy studies and electrochemical techniques are combined to elucidate the effect of Ce and Cr implantation in the formation and evolution of passive layers generated by potentiodyinamic cycling on AISI 304L steel in alkaline medium.Cerium implantation promotes the formation of a thinner and more protective film on the steel. This fact, noticed in X-ray photoelectron

C. M Abreu; M. J Cristóbal; X. R Nóvoa; G Pena; M. C Pérez; C Serra

2004-01-01

131

Effect of high temperature post-oxidizing on tribological and corrosion behavior of plasma nitrided AISI 316 austenitic stainless steel  

Microsoft Academic Search

In this research, the microstructure, tribological and corrosion properties of plasma nitrided-oxidized AISI 316 austenitic stainless steel at high oxidation temperature were studied and compared with conventional plasma nitride. The structural, tribological and corrosion properties were analyzed using XRD, SEM, microhardness testing, pin-on-disk tribotesting and electrochemical polarization. Plasma nitriding was conducted for 5 h at 450 °C with gas mixture of N2\\/H2 = 1\\/3

H. R. Abedi; M. Salehi; M. Yazdkhasti; A. Hemmasian-E

2010-01-01

132

Effects of the high temperature plasma immersion ion implantation (PIII) of nitrogen in AISI H13 steel  

Microsoft Academic Search

In this paper we report the effect of high temperature PIII of nitrogen on the chemical and physical properties of AISI H13\\u000a steel. The implantation of H13 steels was carried out at different temperatures ranging between 300 °C and 720 °C. After the\\u000a treatment, the surface morphology was drastically changed as observed by SEM analysis. Nitrogen penetration depth reaching\\u000a up to 12

L. L. G. da Silva; M. Ueda; C. B. Mello; E. N. Codaro; C. M. Lepienski

2008-01-01

133

Damage assessment in AISI\\/SAE 8620 steel and in a sintered FeP alloy by using acoustic emission  

Microsoft Academic Search

Mechanical behavior of an AISI\\/SAE 8620 steel and of a sintered Fe-P alloy has been investigated using acoustic emission signals.\\u000a Four-point bending tests were carried out using strain gages to measure the deformation. The onset of plastic strain was determined\\u000a through the acoustic signal. The acoustic signal of the sintered material was very strong and increased continually with external\\u000a load.

E. S. Palma; T. R. Mansur

2003-01-01

134

Corrosion resistance properties of glow-discharge nitrided AISI 316L austenitic stainless steel in NaCl solutions  

Microsoft Academic Search

Glow-discharge nitriding treatments can modify the hardness and the corrosion resistance properties of austenitic stainless steels. The modified layer characteristics mainly depend on the treatment temperature. In the present paper the results relative to glow-discharge nitriding treatments carried out on AISI 316L austenitic stainless steel samples at temperatures ranging from 673 to 773K are reported. Treated and untreated samples were

A. Fossati; F. Borgioli; E. Galvanetto; T. Bacci

2006-01-01

135

Low energy isothermal plasma-immersion ion implantation of nitrogen for enhanced hardness of AISI 52100 ball bearing steel  

Microsoft Academic Search

Plasma immersion ion implantation (PIII) is an advanced, plasma-assisted surface engineering technique to enhance resistance to wear, corrosion, etc. The present study concerns PIII of nitrogen ions in AISI 52100 ball bearing steel at low energy (?1 keV) to increase the hardness. The substrate temperature was independently varied up to 500°C with a heater to facilitate diffusion of the implanted

K Ram Mohan Rao; S Mukherjee; P. M Raole; I Manna

2002-01-01

136

High temperature fatigue behavior and residual stress stability of laser-shock peened and deep rolled austenitic steel AISI 304  

Microsoft Academic Search

In this paper, we investigate how laser-shock peening and deep rolling affect the cyclic deformation and S\\/N-behavior of austenitic stainless steel AISI 304 at elevated temperatures (up to 600 °C). The results demonstrate that laser shock peening can produce similar amounts of lifetime enhancements as deep rolling. The cycle, stress amplitude and temperature-dependent relaxation of compressive residual stresses is more

I Nikitin; B Scholtes; H. J Maier; I Altenberger

2004-01-01

137

Electrochemical deposition of black nickel solar absorber coatings on stainless steel AISI316L for thermal solar cells  

Microsoft Academic Search

We report the electrochemical deposition of nanostructured nickel-based solar absorber coatings on stainless steel AISI type 316L. A sol–gel silica-based antireflection coating, from TEOS, was also applied to the solar surface by the dip-coating method. We report our initial results and analyze the influence of the stainless steel substrate on the final total reflectance properties of the solar absorber. The

Mónica Lira-Cantú; Angel Morales Sabio; Alex Brustenga; Pedro Gómez-Romero

2005-01-01

138

Plasma nitriding process by direct current glow discharge at low temperature increasing the thermal diffusivity of AISI 304 stainless steel  

SciTech Connect

This work reports for the first time on the use of the open photoacoustic cell technique operating at very low frequencies and at room temperature to experimentally determine the thermal diffusivity parameter of commercial AISI304 stainless steel and AISI304 stainless steel nitrided samples. Complementary measurements of X-ray diffraction and scanning electron microscopy were also performed. The results show that in standard AISI 304 stainless steel samples the thermal diffusivity is (4.0 {+-} 0.3) Multiplication-Sign 10{sup -6} m{sup 2}/s. After the nitriding process, the thermal diffusivity increases to the value (7.1 {+-} 0.5) Multiplication-Sign 10{sup -6} m{sup 2}/s. The results are being associated to the diffusion process of nitrogen into the surface of the sample. Carrying out subsequent thermal treatment at 500 Degree-Sign C, the thermal diffusivity increases up to (12.0 {+-} 2) Multiplication-Sign 10{sup -6} m{sup 2}/s. Now the observed growing in the thermal diffusivity must be related to the change in the phases contained in the nitrided layer.

Prandel, L. V.; Somer, A.; Assmann, A.; Camelotti, F.; Costa, G.; Bonardi, C.; Jurelo, A. R.; Rodrigues, J. B.; Cruz, G. K. [Universidade Estadual de Ponta Grossa, Grupo de Espectroscopia Optica e Fotoacustica de Materiais, Departamento de Fisica, Av. Carlos Cavalcanti, 4748, CEP 84030-900, Ponta Grossa, PR (Brazil)

2013-02-14

139

Biocompatibility evaluation of surface-treated AISI 316L austenitic stainless steel in human cell cultures.  

PubMed

The effects of AISI 316L austenitic stainless steel, tested in untreated state or subjected to glow-discharge nitriding (at 10 or 20 hPa) and nitriding + post-oxidizing treatments, on human umbilical vein endothelial cells (HUVEC) and on peripheral blood mononuclear cells (PBMC) were evaluated. All the treated samples showed a better corrosion resistance in PBS and higher surface hardness in comparison with the untreated alloy. In HUVEC put in contact for 72 h with the sample types, proliferation and apoptosis decreased and increased, respectively, in the presence of the nitrided + post-oxidized samples, while only slight differences in cytokine (TNF-alpha, IL-6, and TGF-beta1) release were registered. Intercellular adhesion molecule-1 (ICAM-1) increased in HUVEC incubated with all the treated samples, while vascular cell adhesion molecule-1 (VCAM-1) and E-selectin increased in the presence of all the sample types. PBMC incubated for 48 h with the samples showed a decrease in proliferation and an increase in apoptosis in the presence of the untreated samples and the nitrided + post-oxidized ones. All the sample types induced a remarkable increase in TNF-alpha and IL-6 release in PBMC culture medium, while only the untreated sample and the nitrided at 10 hPa induced an increase in ICAM-1 expression. In HUVEC cocultured with PBMC, previously put in contact with the treated AISI 316L samples, increased levels of ICAM-1 were detected. In HUVEC coincubated with the culture medium of PBMC, previously put in contact with the samples under study, a noteworthy increase in ICAM-1, VCAM-1, and E-selectin levels was always registered, with the exception of VCAM-1, which was not affected by the untreated sample. In conclusion, even if the treated samples do not show a marked increase in biocompatibility in comparison with the untreated alloy, their higher corrosion resistance may suggest a better performance as the contact with physiological environment becomes longer. PMID:16983653

Martinesi, M; Bruni, S; Stio, M; Treves, C; Bacci, T; Borgioli, F

2007-01-01

140

Fe-Based Amorphous Coatings on AISI 4130 Structural Steel for Corrosion Resistance  

NASA Astrophysics Data System (ADS)

The current study focuses on synthesizing a novel functional coating for corrosion resistance applications, via laser surface alloying. The iron-based (Fe48Cr15Mo14Y2C15B) amorphous precursor powder is used for laser surface alloying on AISI 4130 steel substrate, with a continuous wave ytterbium Nd-YAG fiber laser. The corrosion resistance of the coatings is evaluated for different processing conditions. The microstructural evolution and the response of the microstructure to the corrosive environment is studied using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Microstructural studies indicate the presence of face-centered cubic Fe-based dendrites intermixed within an amorphous matrix along with fine crystalline precipitates. The corrosion resistance of the coatings decrease with an increase in laser energy density, which is attributed to the precipitation and growth of chromium carbide. The enhanced corrosion resistance of the coatings processed with low energy density is attributed to the self-healing mechanism of this amorphous system.

Katakam, Shravana; Santhanakrishnan, S.; Dahotre, Narendra B.

2012-06-01

141

Carburization behavior of AISI 316LN austenitic stainless steel - Experimental studies and modeling  

NASA Astrophysics Data System (ADS)

AISI type 316LN austenitic stainless steel was exposed to flowing sodium at 798 K for 16,000 h in the bi-metallic (BIM) sodium loop. A modified surface layer of 10 ?m width having a ferrite structure was detected from X-ray diffraction and electron micro probe based analysis. Beneath the modified surface layer a carburized zone of 60 ?m width was identified which was found to consist of M 23C 6 carbides. A mathematical model based on finite difference technique was developed to predict the carburization profiles in sodium exposed austenitic stainless steel. In the computation, effect of only chromium on carbon diffusion was considered. Amount of carbon remaining in solution was determined from the solubility parameter. The predicted profile showed a reasonably good match with the experimental profile. Calculations were extended to simulate the thickness of the carburized layer after exposure to sodium for a period of 40 years. Attempt was also made to predict the carburization profiles based on equilibrium calculations using Dictra and Thermocalc which contain both thermodynamic and kinetic databases for the system under consideration.

Sudha, C.; Sivai Bharasi, N.; Anand, R.; Shaikh, H.; Dayal, R. K.; Vijayalakshmi, M.

2010-07-01

142

Influence of grain size on ultrasonic spectral parameters in AISI type 316 stainless steel  

SciTech Connect

The grain size of a material is an important engineering parameter which influences the mechanical properties such as fatigue, creep, yield strength, impact transition temperature, etc. The reliability of the ultrasonic methods for grain size measurement, particularly amplitude based measurements are highly dependent upon the couplant condition. Therefore, application of these methods may be difficult for some practical applications, where uniform couplant condition can not be maintained. Therefore, it would be useful if a simplified method is developed, which could be used on-line and is free from the above mentioned limitations of the other methods. The shift in the spectral peak frequency has been used for microstructural characterization in carbon steel and for evaluation of structural variations induced by tensile deformation in SUS304 stainless steel. The spectral peak frequency in SUS304 steel was found to increase with increase in the tensile elongation. This was attributed to formation and growth of martensite structures due to tensile deformation resulting in smaller crystalline grains, thus reducing the attenuation due to ultrasonic scattering. The peak frequency has also been found to shift with the change in the grain size in Inconel 600 and copper. In the present study, the shift in the spectral peak frequency and the change in full width at half maximum (FWHM) of the autopower spectrum are correlated with the grain size in AISI type 316 austenitic stainless steel, a widely used structural material in nuclear, chemical, fertilizer and many other industries.

Kumar, A.; Jayakumar, T.; Palanichamy, P.; Raj, B. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Metallurgy and Materials Group] [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Metallurgy and Materials Group

1999-01-08

143

Spinodal decomposition in AISI 316L stainless steel via high-speed laser remelting  

NASA Astrophysics Data System (ADS)

A 1.5 kW CO2 pulsed laser was used to melt the surface of AISI 316L stainless steel with a view to enhancing the surface properties for engineering applications. A 90 ?m laser beam spot size focused onto the surface was used to provide high irradiances (up to 23.56 MW/cm2) with low residence times (as low as 50 ?s) in order to induce rapid surface melting and solidification. Variations in microstructure at different points within the laser treated region were investigated. From this processing refined lamellar and nodular microstructures were produced. These sets of unique microstructures were produced within the remelted region when the highest energy densities were selected in conjunction with the lowest residence times. The transformation from the typical austenitic structure to much finer unique lamellar and nodular structures was attributed to the high thermal gradients achieved using these selected laser processing parameters. These structures resulted in unique characteristics including elimination of cracks and a reduction of inclusions within the treated region. Grain structure reorientation between the bulk alloy and laser-treated region occurred due to the induced thermal gradients. This present article reports on microstructure forms resulting from the high-speed laser surface remelting and corresponding underlying kinetics.

Chikarakara, Evans; Naher, Sumsun; Brabazon, Dermot

2014-05-01

144

Experimental Investigation and Analytical Prediction of ?-Phase Precipitation in AISI 316L Austenitic Stainless Steel  

NASA Astrophysics Data System (ADS)

The phase precipitation in industrial AISI 316L stainless steel during aging for up to 80,000 hours between 823 K and 1073 K (550 °C and 800 °C) has been studied using transmission electron microscopy, scanning transmission electron microscopy, and carbon replica energy-dispersive X-ray microanalysis. Three phases were identified: Chromium carbides (M23C6), Laves phase ( ?), and ?-phase (Fe-Cr). M23C6 carbide precipitation occurred firstly and was followed by the ? and ?-phases at grain boundaries when the aging temperature is higher than 873 K (600 °C). Precipitation and growth of M23C6 create chromium depletion zones at the grain boundaries and also retard the ?-phase formation. Thus, the ?-phase is controlled by the kinetic of chromium bulk diffusion and can appear only when the chromium reaches, at grain boundaries and at the M23C6/ ? and M23C6/ ?/ ? interfaces, content higher than a critical value obtained by self-healing. An analytical model, based on equivalent chromium content, has been established in this study and successfully validated to predict the time-temperature-precipitation diagram of the ?-phase. The obtained diagram is in good agreement with the experimental results.

Sahlaoui, Habib; Sidhom, Habib

2013-07-01

145

DCEMS Study of Thin Stainless Steel Films Deposited by RF Sputtering of AISI316L  

SciTech Connect

Thin stainless steel films were prepared on SiO2/Si plate heated at 100 deg. C and 400 deg. C using AISI316L as target, by a RF magnetron Ar sputtering method. RF sputtered-deposited films and the oxidized surface layers by post heating were characterized by depth selective conversion electron Moessbauer spectroscopy (DCEMS) using a He+5%CH4 gas proportional counter. The as-deposited films consisted of magnetic phases, the magnetic orientation of which had a tendency to be perpendicular to the surface of the film. In the case of the deposited films at substrate temperature of 100 deg. C, a small amount of Fe2O3 and ferritic stainless steel formed by post-heating in air. A magnetic subcomponent and a austenite phase were formed in the films deposited at substrate temperature of 400 deg. C. {alpha}-Fe2O3 and magnetite formed easily on the top and middle layers of the films by post-heating in air. The oxide states of the films deposited at different temperatures of substrate were clearly distinguished by post-heating. Thus it was found by DCEMS that the structures of the deposited films were strongly affected by the preparation method and the temperature of the substrate.

Nomura, K.; Iio, S.; Ujihira, Y.; Terai, T. [School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2005-04-26

146

An experimental investigation of pulsed laser-assisted machining of AISI 52100 steel  

NASA Astrophysics Data System (ADS)

Grinding and hard turning are widely used for machining of hardened bearing steel parts. Laser-assisted machining (LAM) has emerged as an efficient alternative to grinding and hard turning for hardened steel parts. In most cases, continuous-wave lasers were used as a heat source to cause localized heating prior to material removal by a cutting tool. In this study, an experimental investigation of pulsed laser-assisted machining of AISI 52100 bearing steel was conducted. The effects of process parameters (i.e., laser mean power, pulse frequency, pulse energy, cutting speed and feed rate) on state variables (i.e., material removal temperature, specific cutting energy, surface roughness, microstructure, tool wear and chip formation) were investigated. At laser mean power of 425 W with frequency of 120 Hz and cutting speed of 70 m/min, the benefit of LAM was shown by 25% decrease in specific cutting energy and 18% improvement in surface roughness, as compared to those of the conventional machining. It was shown that at constant laser power, the increase of laser pulse energy causes the rapid increase in tool wear rate. Pulsed laser allowed efficient control of surface temperature and heat penetration in material removal region. Examination of the machined subsurface microstructure and microhardness profiles showed no change under LAM and conventional machining. Continuous chips with more uniform plastic deformation were produced in LAM.

Panjehpour, Afshin; Soleymani Yazdi, Mohammad R.; Shoja-Razavi, Reza

2014-11-01

147

The Meta-Lax method of stress reduction in welds. [ASTM A36; AISI 4140  

SciTech Connect

This study is the second phase of ongoing research into the mechanics and feasibility of using the Meta-Lax method of vibratory stress relief in place of thermal methods of stress relief. The first phase of this research revealed results that were similar to, and even superior to those achieved using thermal methods. The testing here was designed to eliminate the effects of interbead tempering by utilizing single pass bead-on-plate welds only. A metallurgical explanation for the success of the Meta-Lax method was not found. No significant structure or chemical changes were noted when used with ASTM A36 or AISI 4140 materials, and the phenomena noted in phase I was apparently due to interbead tempering. The theory of accelerated aging has been proposed and studies exist which observed dislocation motion as a result of vibratory treatment. It is evident that the vibratory stress relief system does not impart sufficient energy to bring about the magnitude of change seen with thermal methods. however the physical improvement is a reality, and vibratory methods should be evaluated further.

Smith, S.M.

1992-07-31

148

Investigation of Low-Cycle Bending Fatigue of AISI 9310 Steel Spur Gears  

NASA Technical Reports Server (NTRS)

An investigation of the low-cycle bending fatigue of spur gears made from AISI 9310 gear steel was completed. Tests were conducted using the single-tooth bending method to achieve crack initiation and propagation. Tests were conducted on spur gears in a fatigue test machine using a dedicated gear test fixture. Test loads were applied at the highest point of single tooth contact. Gear bending stresses for a given testing load were calculated using a linear-elastic finite element model. Test data were accumulated from 1/4 cycle to several thousand cycles depending on the test stress level. The relationship of stress and cycles for crack initiation was found to be semilogarithmic. The relationship of stress and cycles for crack propagation was found to be linear. For the range of loads investigated, the crack propagation phase is related to the level of load being applied. Very high loads have comparable crack initiation and propagation times whereas lower loads can have a much smaller number of cycles for crack propagation cycles as compared to crack initiation.

Handschuh, Robert F.; Krantz, Timothy L.; Lerch, Bradley A.; Burke, Christopher S.

2007-01-01

149

An Electrochemical Processing Strategy for Improving Tribological Performance of Aisi 316 Stainless Steel Under Grease Lubrication  

NASA Astrophysics Data System (ADS)

In order to improve the tribological performance of AISI 316 stainless steel (316 SS) under grease lubrication, electrochemical processing was conducted on it to obtain a rough (surface texturing-like) surface by making use of the high sensitivity of austenitic stainless steel to pitting corrosion in Cl--rich environment. Numerous corrosion pits or micro-ditches acted as micro-reservoirs on the obtained surface. While the grease could offer consistent lubrication, and then improve the tribological performance of 316 SS. Tribological behaviors of raw 316 SS and the treated sample were measured using a reciprocating type tribometer sliding against GCr15 steel counterpart under dry and grease lubrication conditions. The results showed that the mass losses of the two samples were in the same order of magnitude, and the raw sample exhibited lower friction coefficient in dry sliding. When the tests were conducted under grease lubrication condition, the friction coefficients and mass losses of the treated sample were far lower than those of the raw 316 SS. The tribological performance of 316 SS under grease lubrication was drastically improved after electrochemical processing.

Zou, Jiaojuan; Li, Maolin; Lin, Naiming; Zhang, Xiangyu; Qin, Lin; Tang, Bin

2014-12-01

150

Investigation of Low-Cycle Bending Fatigue of AISI 9310 Steel Spur Gears  

NASA Technical Reports Server (NTRS)

An investigation of the low-cycle bending fatigue of spur gears made from AISI 9310 gear steel was completed. Tests were conducted using the single-tooth bending method to achieve crack initiation and propagation. Tests were conducted on spur gears in a fatigue test machine using a dedicated gear test fixture. Test loads were applied at the highest point of single tooth contact. Gear bending stresses for a given testing load were calculated using a linear-elastic finite element model. Test data were accumulated from 1/4 cycle to several thousand cycles depending on the test stress level. The relationship of stress and cycles for crack initiation was found to be semi-logarithmic. The relationship of stress and cycles for crack propagation was found to be linear. For the range of loads investigated, the crack propagation phase is related to the level of load being applied. Very high loads have comparable crack initiation and propagation times whereas lower loads can have a much smaller number of cycles for crack propagation cycles as compared to crack initiation.

Handschuh, Robert F.; Krantz, Timothy L.; Lerch, Bradley A.; Burke, Christopher S.

2007-01-01

151

Phase Transformations During the Low-Temperature Nitriding of AISI 2205 Duplex Stainless Steel  

NASA Astrophysics Data System (ADS)

Liquid nitriding of type AISI 2205 duplex stainless steel was conducted at 723 K (450 °C), using one type of novel low-temperature liquid chemical thermo-treatment. The transformation of the nitrided surface microstructure was systematically studied. Experimental results revealed that a nitrided layer formed on the sample surface with the thickness ranging from 3 to 28 ?m, depending on nitriding time. After the 2205 duplex stainless steel was subjected to liquid nitriding 723 K (450 °C) for less than 8 hours, the pre-existing ferrite region on the surface transformed into the expanded austenite (S phase) by the infusion of nitrogen atoms, most of which stay in the interstitial sites. Generally, the dominant phase of the nitrided layer was the expanded austenite. When the nitriding time prolonged up to 16 hours, some pre-existing ferrite in expanded austenite was decomposed and ?-nitride precipitated subsequently. When the treatment time went up to 40 hours, large amount of ?-nitride and CrN precipitates were observed in the pre-existing ferritic region in the expanded austenite. Furthermore, many nitrides precipitated from the pre-austenite region. Acicular nitride was identified by transmission electron microscopy. The thickness of the nitrided layer increased with increasing nitriding time. The growth of the nitrided layer is mainly due to nitrogen diffusion in accordance with the expected parabolic rate law. Liquid nitriding effectively increased the surface hardness of 2205 duplex stainless steel by a factor of 3.

Yan, Jing; Gu, Tan; Qiu, Shaoyu; Wang, Jun; Xiong, Ji; Fan, Hongyuan

2015-02-01

152

Effect of welding parameters on the heat-affected zone of AISI409 ferritic stainless steel  

NASA Astrophysics Data System (ADS)

One of the main problems during the welding of ferritic stainless steels is severe grain growth within the heat-affected zone (HAZ). In the present study, the microstructural characteristics of tungsten inert gas (TIG) welded AISI409 ferritic stainless steel were investigated by electron backscattered diffraction (EBSD), and the effects of welding parameters on the grain size, local misorientation, and low-angle grain boundaries were studied. A 3-D finite element model (FEM) was developed to predict the effects of welding parameters on the holding time of the HAZ above the critical temperature of grain growth. It is found that the base metal is not fully recrystallized. During the welding, complete recrystallization is followed by severe grain growth. A decrease in the number of low-angle grain boundaries is observed within the HAZ. FEM results show that the final state of residual strains is caused by competition between welding plastic strains and their release by recrystallization. Still, the decisive factor for grain growth is heat input.

Ranjbarnodeh, Eslam; Hanke, Stefanie; Weiss, Sabine; Fischer, Alfons

2012-10-01

153

Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding  

NASA Astrophysics Data System (ADS)

A fully coupled (two-way), transient, thermal-mechanical finite-element procedure is developed to model conventional gas metal arc welding (GMAW) butt-joining process. Two-way thermal-mechanical coupling is achieved by making the mechanical material model of the workpiece and the weld temperature-dependent and by allowing the potential work of plastic deformation resulting from large thermal gradients to be dissipated in the form of heat. To account for the heat losses from the weld into the surroundings, heat transfer effects associated with natural convection and radiation to the environment and thermal-heat conduction to the adjacent workpiece material are considered. The procedure is next combined with the basic physical-metallurgy concepts and principles and applied to a prototypical (plain) low-carbon steel (AISI 1005) to predict the distribution of various crystalline phases within the as-welded material microstructure in different fusion zone and heat-affected zone locations, under given GMAW-process parameters. The results obtained are compared with available open-literature experimental data to provide validation/verification for the proposed GMAW modeling effort.

Grujicic, M.; Ramaswami, S.; Snipes, J. S.; Yavari, R.; Arakere, A.; Yen, C.-F.; Cheeseman, B. A.

2013-05-01

154

Effect of lubricant extreme-pressure additives on surface fatigue life of AISI 9310 spur gears  

NASA Technical Reports Server (NTRS)

Surface fatigue tests were conducted with AISI 9310 spur gears using a formulated synthetic tetraester oil (conforming to MIL-L-23699 specifications) as the lubricant containing either sulfur or phosphorus as the EP additive. Four groups of gears were tested. One group of gears tested without an additive in the lubricant acted as the reference oil. In the other three groups either a 0.1 wt % sulfur or phosphorus additive was added to the tetraester oil to enhance gear surface fatigue life. Test conditions included a gear temperature of 334 K (160 F), a maximum Hertz stress of 1.71 GPa (248 000 psi), and a speed of 10,000 rpm. The gears tested with a 0.1 wt % phosphorus additive showed pitting fatigue life 2.6 times the life of gears tested with the reference tetraester based oil. Although fatigue lives of two groups of gears tested with the sulfur additive in the oil showed improvement over the control group gear life, the results, unlike those obtained with the phosphorus oil, were not considered to be statistically significant.

Scibbe, H. W.; Townsend, D. P.; Aron, P. R.

1984-01-01

155

Influence of prior deformation on the sensitization of AISI Type 316LN stainless steel  

NASA Astrophysics Data System (ADS)

The sensitization behaviour of a nuclear grade AISI 316LN stainless steel (SS) was studied for various cold-work levels ranging from 0% (mill-annealed) to 25% reduction in thickness. ASTM standard A262 Practices A and E were adopted to detect the susceptibility to intergranular corrosion. The results obtained in these tests were used to construct time-temperature-sensitization (TTS) diagrams. Using these data, the critical linear cooling rate was calculated, above which there is no risk of sensitization. In order to predict the sensitization behaviour during practical cooling conditions, Continuous-cooling-sensitization (CCS) diagrams were established utilising the TTS diagrams by a mathematical method. The influences of prior deformation and nitrogen in the alloy on the sensitization kinetics are discussed. It was found that nitrogen addition retards the sensitization kinetics and that tmin (minimum time required for sensitization at nose temperature) increases by two orders of magnitude in Type 316LN SS compared to that of Type 316 SS at the different prior deformation levels. Cold-working up to 15% accelerates the onset of carbide precipitation and on further cold working there is not much difference in the kinetics. Desensitization is faster in highly cold-worked material, especially at high temperatures.

Parvathavarthini, N.; Dayal, R. K.; Gnanamoorthy, J. B.

1994-02-01

156

The effects of cold working on sensitization and intergranular corrosion behavior of AISI 304 stainless steel  

NASA Astrophysics Data System (ADS)

The effects of prior cold rolling of up to an 80 pct reduction in thickness on the sensitization-desensitization behavior of Type AISI 304 stainless steel and its susceptibility to intergranular corrosion have been studied by electrochemical potentiokinetic reactivation (EPR) and Strauss-test methods. The results indicate that the prior deformation accelerated the sensitization as compared to the undeformed stainless steel. The deformed Type 304 stainless steel experienced desensitization at higher temperatures and times, and it was found to be enhanced by increased cold deformation. This could be attributed to the increased long-range chromium diffusion, possibly brought on by increasing pipe diffusion and vacancies. The role of the deformation-induced martensite (DIM) and texture, introduced by uniaxial cold rolling, on the sensitization-desensitization kinetics has also been discussed. This study could not reveal any systematic relationship between texture and the degree of sensitization (DOS) obtained. The effect of DIM on DOS seems to be pronounced at 500 °C when the steel retained significant amounts of DIM; however, the retained DIM is insignificant at higher sensitization times and temperatures.

Singh, Raghuvir; Chattoraj, I.; Kumar, A.; Ravikumar, B.; Dey, P. K.

2003-11-01

157

Prediction of Cutting Forces Using ANNs Approach in Hard Turning of AISI 52100 steel  

SciTech Connect

In this study, artificial neural networks (ANNs) was used to predict cutting forces in the case of machining the hard turning of AISI 52100 bearing steel using cBN cutting tool. Cutting forces evolution is considered as the key factors which affect machining. Predicting cutting forces evolution allows optimizing machining by an adaptation of cutting conditions. In this context, it seems interesting to study the contribution that could have artificial neural networks (ANNs) on the machining forces prediction in both numerical and experiment studies. Feed-forward multi-layer neural networks trained by the error back-propagation (BP) algorithm are used. Levenberg-Marquardt (LM) optimization algorithm was used for finding out weights. The training of the network is carried out with experimental machining data.The input dataset used are cutting speed, feed rate, cutting depth and hardness of the material. The output dataset used are cutting forces (Ft-cutting force, Fa- feed force and Fr- radial force).Results of the neural networks approach, in comparison with experimental data are discussed in last part of this paper.

Makhfi, Souad [Laboratoire des Technologies Industrielles. Universite Ibn Khaldoun de Tiaret, B.P. 78, Tiaret 14000 (Algeria); Laboratoire des Technologies Innovantes E.A. 3899. I.U.T. GMP-Universite de Picardie Jules Verne, avenue des Facultes, Le Bailly, 80025 Amiens Cedex1 (France); Habak, Malek; Velasco, Raphael [Laboratoire des Technologies Innovantes E.A. 3899. I.U.T. GMP-Universite de Picardie Jules Verne, avenue des Facultes, Le Bailly, 80025 Amiens Cedex1 (France); Haddouche, Kamel; Vantomme, Pascal [Laboratoire des Technologies Industrielles. Universite Ibn Khaldoun de Tiaret, B.P. 78, Tiaret 14000 (Algeria)

2011-05-04

158

White Layer Formation Due to Phase Transformation to Orthogonal machine of AISI 1045 Annealed Steel  

SciTech Connect

It is commonly believed that the white layer formed during machining of steels is caused primarily by a thermally induced phase transformation resulting from rapid heating and quenching. As a result, it is often assumed that if the temperature at the tool flank-workpiece interface exceeds the nominal phase transformation temperature for the steel, a white layer forms. However, no attempt has been made to actually measure the temperatures produced at the tool flank-workpiece interface and correlate it with microstructural evidence of phase transformation. This paper aims to address these limitations through suitably designed experiments and analysis. Orthogonal machining tests were performed on AISI 1045 annealed steel at different cutting speeds and tool flank wear. During machining, temperature measurements at the tool flank-workpiece interface were made using an exposed thermocouple technique. Metallographic studies of the machined sub-surface and X-ray diffraction (XRD) measurements were performed to determine the presence and depth of white layer, and the presence of the retained austenite phase in the machined surface layer, respectively. Analysis of the data shows that the white layer can form due to phase transformation at temperatures below the nominal austenitization temperature of the steel. Possible causes of this result are presented.

Han, Sangil [ORNL; Melkote, Shreyes N [Georgia Institute of Technology; Haluska, Dr. Michael S [Georgia Institute of Technology; Watkins, Thomas R [ORNL

2008-01-01

159

Characterization of irradiated AISI 316L stainless steel disks removed from the Spallation Neutron Source  

SciTech Connect

Irradiated AISI 316L stainless steel disks were removed from the Spallation Neutron Source (SNS) for post-irradiation examination (PIE) to assess mechanical property changes due to radiation damage and erosion of the target vessel. Topics reviewed include high-resolution photography of the disk specimens, cleaning to remove mercury (Hg) residue and surface oxides, profile mapping of cavitation pits using high frequency ultrasonic testing (UT), high-resolution surface replication, and machining of test specimens using wire electrical discharge machining (EDM), tensile testing, Rockwell Superficial hardness testing, Vickers microhardness testing, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effectiveness of the cleaning procedure was evident in the pre- and post-cleaning photography and permitted accurate placement of the test specimens on the disks. Due to the limited amount of material available and the unique geometry of the disks, machine fixturing and test specimen design were critical aspects of this work. Multiple designs were considered and refined during mock-up test runs on unirradiated disks. The techniques used to successfully machine and test the various specimens will be presented along with a summary of important findings from the laboratory examinations.

Vevera, Bradley J [ORNL] [ORNL; Hyres, James W [ORNL] [ORNL; McClintock, David A [ORNL] [ORNL; Riemer, Bernie [ORNL] [ORNL

2014-01-01

160

Investigation of wear behavior and chip formation for cutting tools with nano-multilayered TiAlCrN\\/NbN PVD coating  

Microsoft Academic Search

A comprehensive investigation of the wear progress and chip formation was performed on an ultra-fine-grained cemented carbide ball nose end mill coated with a novel nano-multilayered TiAlCrN\\/NbN coating, by dry machining-hardened steel AISI H13 (HRC 55–57) at a cutting speed of 300m\\/min. Flank wear and cutting forces were measured as the wear progressed; chip temperatures were estimated. The surface morphology

L. Ning; S. C. Veldhuis; K. Yamamoto

2008-01-01

161

Investigations on friction and wear mechanisms of the PVD-TiAlN coated carbide in dry sliding against steels and cast iron  

Microsoft Academic Search

The tribological behaviour of the monolayer PVD-titanium aluminium nitride (TiAlN) coated carbide inserts in unidirectional dry sliding against steel and cast iron counterparts was investigated using the pin-on-disc standard test with varying sliding speeds and normal loads. Three different materials of various machinability rates were used as the counterparts, namely the normalised medium carbon steel C45 equivalent to AISI 1045,

W. Grzesik; Z. Zalisz; S. Krol; P. Nieslony

2006-01-01

162

Mechanical behavior of AISI 304SS determined by miniature test methods after neutron irradiation to 28 dpa  

SciTech Connect

The mechanical properties of AISI 304 stainless steel irradiated for over a decade in the Experimental Breeder Reactor (EBR-II) were measured using miniature mechanical testing methods. The shear punch method was used to evaluate the shear strengths of the neutron-irradiated steel and a correlation factor was empirically determined to predict its tensile strength. The strength of the stainless steel slightly decreased with increasing irradiation temperature, and significantly increased with increasing dose until it saturated above approximately 5 dpa. Ferromagnetic measurements were used to observe and deduce the effects of the stress-induced austenite to martensite transformation as a result of shear punch testing.

Ellen M. Rabenberg; Brian J. Jaques; Bulent H. Sencer; Frank A. Garner; Paula D. Freyer; Taira Okita; Darryl P. Butt

2014-05-01

163

Effect of martensite to austenite reversion on the formation of nano/submicron grained AISI 301 stainless steel  

SciTech Connect

The martensite to austenite reversion behavior of 90% cold rolled AISI 301 stainless steel was investigated in order to refine the grain size. Cold rolled specimens were annealed at 600-900 deg. C, and subsequently characterized by scanning electron microscopy, X-ray diffraction, Feritscope, and hardness measurements. The effects of annealing parameters on the formation of fully-austenitic nano/submicron grained structure and the mechanisms involved were studied. It was found that annealing at 800 deg. C for 10 s exhibited the smallest average austenite grain size of 240 {+-} 60 nm with an almost fully-austenitic structure.

Karimi, M.; Najafizadeh, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Kermanpur, A., E-mail: ahmad_k@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Eskandari, M. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2009-11-15

164

Wear resistance of TiAlSiN thin coatings.  

PubMed

In the last decades TiAIN coatings deposited by PVD techniques have been extensively investigated but, nowadays, their potential development for tribological applications is relatively low. However, new coatings are emerging based on them, trying to improve wear behavior. TiAlSiN thin coatings are now investigated, analyzing if Si introduction increases the wear resistance of PVD films. Attending to the application, several wear test configurations has been recently used by some researchers. In this work, TiAISiN thin coatings were produced by PVD Unbalanced Magnetron Sputtering technique and they were conveniently characterized using Scanning Electron Microscopy (SEM) provided with Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Electron Probe Micro-Analyzer (EPMA), Micro Hardness (MH) and Scratch Test Analysis. Properties as morphology, thickness, roughness, chemical composition and structure, hardness and film adhesion to the substrate were investigated. Concerning to wear characterization, two very different ways were chosen: micro-abrasion with ball-on-flat configuration and industrial non-standardized tests based on samples inserted in a feed channel of a selected plastic injection mould working with 30% (wt.) glass fiber reinforced polypropylene. TiAISiN coatings with a small amount of about 5% (wt.) Si showed a similar wear behavior when compared with TiAIN reported performances, denoting that Si addition does not improve the wear performance of the TiAIN coatings in these wear test conditions. PMID:23447962

Silva, F J G; Martinho, R P; Alexandre, R J D; Baptista, A P M

2012-12-01

165

Inclusion engineering for improved fatigue response in forged AISI 4140 steel  

SciTech Connect

Small elemental additions to a steel melt can increase the flow stress of MnS inclusions, making them less deformable during hot working. This condition, called inclusion shape control, is a powerful tool for improving transverse fatigue life of 4140 steel. This research explored the effects of forging on changing the shape and distribution of MnS inclusions, and their role as fatigue initiation sites. The steels in the test matrix were chosen to examine forging effects on inclusions in steel with high and low sulfur levels. One heat had been treated for inclusion shape control. Billets, 127-mm (5-in.) in diameter and 248-mm (9.7-in) high, from bar stock of three heats of inert-gas-shielded/bottom poured (IGS) AISI 4140 steel were upset forged at 1,200 C (2,200 F) to a 50% reduction. A two-dimensional FEM program was used to model the forging process. FEM results at discrete elements were compared with the fatigue response of specimens machined from actual forgings to contain those elements in their gage sections. Both transverse and longitudinal fatigue specimens were machined, and heat treated to obtain a tempered martensite microstructure of approximately 38 HRC. The specimens were tested in tension cycling (R = 0.1) at {sigma}{sub max} = 825 to 965 MPa (120 to 140 ksi). Fatigue results were normalized to a single stress level using a modified Smith-Watson-Topper function. The normalized results were correlated with position in the forgings and calculated effective strains due to forging at those locations. Metallography and fractography were also used to examine inclusion morphologies in regions of low and high local effective strains.

Collins, S.R. [NUPRO Co., Willoughby, OH (United States); Michal, G.M. [Case Western Reserve Univ., Cleveland, OH (United States)

1995-12-31

166

Multi-component boron coatings on low carbon steel AISI 1018  

NASA Astrophysics Data System (ADS)

Boronizing and metalizing are thermo-chemical surface hardening treatments in which boron and metal atoms diffuse into the metal substrate forming metallic boride layers, providing complex properties of B-Me-Fe system. To study multi-component boron coatings on low carbon steel AISI 1018, the simultaneous powder pack method of boronizing and metalizing was selected to perform the coatings. One B-Fe system and eight boron-metal (B-Me-Fe) systems from transition metals group IVB (Ti, Zr, HO, group VB (Nb, Ta), and group VIB (Cr, Mo, W) were studied. The system specimens were thereto-chemically treated at 950°C for 4 hours in a crucible containing powder mixture of boron source, transition metal powder, and activator. After the heat treatment process, the multi-component boron coatings were characterized by using optical microscope, microhardness tester, TGA, XRD, and Synchrotron microdiffraction. The coating morphology was observed and the coating thickness was measured as well as the microhardness across the depth of coating. The corrosion resistance of the coatings was evaluated by the continuous weighting method. The high temperature oxidation was also detected by isothermal method at a temperature range of 400-800°C for 24 hours. The Rietveld refinement method was used to examine the quantitative phase analysis, crystalline size, microstrain and lattice parameters of the multi-component boron coatings. The results have shown that adding transition metals into the B-Fe system caused the formation of solid solution of transition-metal borides. The distortion of crystal lattice parameters generated microstrain in the boride phase. The Synchrotron microdiffraction confirmed the presence of about 5-10 microns of transition-metal boride phase at the surface. Moreover, the additional transition metal can provide better corrosion and high temperature oxidation resistance to the B-Fe system, preventing the deboronizing and stabilizing the boride phases.

Suwattananont, Naruemon

167

Investigation of AISI 441 Ferritic Stainless Steel and Development of Spinel Coatings for SOFC Interconnect Applications  

SciTech Connect

As part of an effort to develop cost-effective ferritic stainless steel-based interconnects for solid oxide fuel cell (SOFC) stacks, both bare and spinel coated AISI 441 were studied in terms of metallurgical characteristics, oxidation behavior, and electrical performance. The conventional melt metallurgy used for the bulk alloy fabrication leads to significant processing cost reduction and the alloy chemistry with the presence of minor alloying additions of Nb and Ti facilitate the strengthening by precipitation and formation of Laves phase both inside grains and along grain boundaries during exposure in the intermediate SOFC operating temperature range. The Laves phase formed along the grain boundaries also ties up Si and prevents the formation of an insulating silica layer at the scale/metal interface during prolonged exposure. The substantial increase in ASR during long term oxidation due to oxide scale growth suggested the need for a conductive protection layer, which could also minimize Cr evaporation. In particular, Mn1.5Co1.5O4 based surface coatings on planar coupons drastically improved the electrical performance of the 441, yielding stable ASR values at 800ºC for over 5,000 hours. Ce-modified spinel coatings retained the advantages of the unmodified spinel coatings, and also appeared to alter the scale growth behavior beneath the coating, leading to a more adherent scale. The spinel protection layers appeared also to improve the surface stability of 441 against the anomalous oxidation that has been observed for ferritic stainless steels exposed to dual atmosphere conditions similar to SOFC interconnect environments. Hence, it is anticipated that, compared to unmodified spinel coatings, the Ce-modified coatings may lead to superior structural stability and electrical performance.

Yang, Zhenguo; Xia, Guanguang; Wang, Chong M.; Nie, Zimin; Templeton, Joshua D.; Singh, Prabhakar; Stevenson, Jeffry W.

2008-05-30

168

Fracture toughness of aisi M2 high-speed steel and corresponding matrix tool steel  

NASA Astrophysics Data System (ADS)

The influence of microstructural variations on the fracture toughness of two tool steels with compositions 6 pct W-5 pct Mo-4 pct Cr-2 pct V-0.8 pct C (AISI M2 high-speed steel) and 2 pct W-2.75 pct Mo-4.5 pct Cr-1 pct V-0.5 pct C (VASCO-MA) was investigated. In the as-hardened condition, the M2 steel has a higher fracture toughness than the MA steel, although the latter steel is softer. In the tempered condition, MA is softer and has a higher fracture toughness than M2. When the hardening temperature is below 1095 °C (2000 °F), tempering of both steels causes embrittlement, i.e., a reduction of fracture toughness as well as hardness. The fracture toughness of both steels was enhanced by increasing the grain size. The steel samples with intercept grain size of 5 (average grain diameter of 30 microns) or coarser exhibit 2 to 3 MPa?m (2 to 3 ksi?in.) higher fracture toughness than samples with intercept grain size of 10 (average grain diameter of 15 microns) or finer. Tempering temperature has no effect on the fracture toughness of M2 and MA steels as long as the final tempered hardness of the steels is constant. Retained austenite has no influence on the fracture toughness of as-hardened MA steel, but a high content of retained austenite appears to raise the fracture toughness of as-hardened M2 steel. There is a temperature of austenitization for each tool steel at which the retained austenite content in the as-quenched samples is a maximum. The above described results were explained through changes in the microstructure and the fracture modes.

Kim, Chongmin; Johnson, A. Richard; Hosford, William F.

1982-09-01

169

ALS - resources  

MedlinePLUS

Resources - ALS ... The following organizations are good resources for information on amyotrophic lateral sclerosis : Muscular Dystrophy Association - http://mda.org/disease/amyotrophic-lateral-sclerosis National Amyotrophic Lateral Sclerosis (ALS) ...

170

Effect of cold working and sandblasting on the microhardness, tensile strength and corrosion resistance of AISI 316L stainless steel  

NASA Astrophysics Data System (ADS)

The aim of this work is to investigate the effect of cold working and sandblasting on the microhardness, tensile strength and corrosion rate of AISI 316L stainless steel. The specimens were deformed from 17% to 47% and sandblasted for 20 min using SiC particles with a diameter of 500-700 ?m and an air flow with 0.6-0.7 MPa pressure. The microhardness distribution and tensile test were conducted and a measurement on the corrosion current density was done to determine the corrosion rate of the specimens. The result shows that the cold working enhances the bulk microhardness, tensile and yield strength of the specimen by the degree of deformation applied in the treatment. The sandblasting treatment increases the microhardness only at the surface of the specimen without or with a low degree of deformation. In addition, the sandblasting enhances the surface roughness. The corrosion resistance is improved by cold working, especially for the highly deformed specimen. However the follow-up sandblasting treatment reduces the corrosion resistance. In conclusion, the cold working is prominent to be used for improving the mechanical properties and corrosion resistance of AISI 316L stainless steel. Meanwhile, the sandblasting subjected to the cold worked steel is only useful for surface texturing instead of improving the mechanical properties and corrosion resistance.

Suyitno; Arifvianto, Budi; Widodo, Teguh Dwi; Mahardika, Muslim; Dewo, Punto; Salim, Urip Agus

2012-12-01

171

High temperature oxidation behavior of austenitic stainless steel AISI 304 in steam of nanofluids contain nanoparticle ZrO2  

SciTech Connect

The objective of this study is to evaluate high temperature oxidation behavior of austenitic stainless steel SS 304 in steam of nanofluids contain nanoparticle ZrO{sub 2}. The oxidation was performed at high temperatures ranging from 600 to 800°C. The oxidation time was 60 minutes. After oxidation the surface of the samples was analyzed by different methods including, optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD). X-ray diffraction examination show that the oxide scale formed during oxidation of stainless steel AISI 304 alloys is dominated by iron oxide, Fe{sub 2}O{sub 3}. Minor element such as Cr{sub 2}O{sub 3} is also appeared in the diffraction pattern. Characterization by optical microscope showed that cross section microstructure of stainless steel changed after oxidized with the oxide scale on the surface stainless steels. SEM and x-ray diffraction examination show that the oxide of ZrO{sub 2} appeared on the surface of stainless steel. Kinetic rate of oxidation of austenite stainless steel AISI 304 showed that increasing oxidation temperature and time will increase oxidation rate.

Prajitno, Djoko Hadi, E-mail: djokohp@batan.go.id; Syarif, Dani Gustaman, E-mail: djokohp@batan.go.id [Research Center for Nuclear Materials and Radiometry, Jl. Tamansari 71, Bandung 40132 (Indonesia)

2014-03-24

172

Effect of Filler Metals on the Weldability and Mechanical Properties of Multi-pass PCGTA Weldments of AISI 316L  

NASA Astrophysics Data System (ADS)

The influence of filler metals on the microstructure, mechanical properties, and corrosion behavior of AISI 316L welds was investigated. Pulsed current gas tungsten arc welding was employed to join the AISI 316L plates using two different fillers ER2553 and ERNiCr-3. Microstructures studies showed the presence of different forms of austenite on employing ER2553 filler and formation of migrated grain boundaries at the weld zone while using ERNiCr-3 filler. Tensile studies corroborated that the tensile strength was greater for the weldments employing ER2553 filler. Charpy V-notch studies ascertained that the impact toughness was greater for ER2553 weldments as compared to the parent metal. Potentiodynamic polarization curves clearly inferred that the weld zone of ER2553 exhibited better corrosion resistance among the various coupons tested. It was concluded from the study that ER2553 exhibited better mechanical and corrosion properties and could be adopted to achieve optimal properties compared to over-alloyed filler.

Devendranath Ramkumar, K.; Maruthi Mohan Reddy, P.; Raja Arjun, B.; Choudhary, Ayush; Srivastava, Anubhav; Arivazhagan, N.

2015-04-01

173

Swelling and creep observed in AISI 304 fuel pin cladding from three MOX fuel assemblies irradiated in EBR-II  

NASA Astrophysics Data System (ADS)

Three 37-pin MOX-fueled experimental subassemblies were irradiated in EBR-II with fuel pin cladding constructed from annealed AISI 304 stainless steel. Analysis of the swelling and irradiation creep of the cladding showed that the terminal swelling rate of AISI 304 stainless steel appears to be ˜1%/dpa and that swelling is very reproducible for identical irradiation conditions. The swelling at a given neutron fluence is rather sensitive to both irradiation temperature and especially to the neutron flux, however, with the primary influence residing in the transient regime. As the neutron flux increases the duration of the transient regime is increased in agreement with other recent studies. The duration of the transient regime is also decreased by increasing irradiation temperature. In these assemblies swelling reached high levels rather quickly, reducing the opportunity for fuel pin cladding interaction and thereby reducing the contribution of irradiation creep to the total deformation. It also appears that in this swelling-before-creep scenario that the well-known "creep disappearance" phenomenon was operating strongly.

Garner, F. A.; Makenas, B. J.; Chastain, S. A.

2011-06-01

174

The role of creep and fatigue in determining the high-temperature behaviour of AISI H11 tempered steel for aluminium extrusion dies  

Microsoft Academic Search

The present study was aimed to analyze the effect of loading cycles on the behaviour of the AISI H11 tool steel commonly used for aluminium extrusion dies working at high temperatures and under high, cyclic stresses. A technological test method in which the specimen geometry resembled the mandrel of a hollow extrusion die was developed. Finite element analyses were performed

B. Reggiani; L. Donati; J. Zhou; L. Tomesani

2010-01-01

175

Influence of micro structure on acoustic emission behavior during stage 2 fatigue crack growth in solution annealed, thermally aged and weld specimens of AISI type 316 stainless steel  

Microsoft Academic Search

Acoustic emission (AE) behavior during fatigue crack growth (FCG) in solution annealed, thermally aged and weld specimens of AISI type 316 austenitic stainless steel is reported in this article. The presence of two substages 2(a) and 2(b) during stage 2 FCG could be distinguished by a change in the AE behavior corresponding to a sharp change in the crack growth

V. Moorthy; T. Jayakumar; Baldev Raj

1996-01-01

176

Welding procedure specification. Supplement 1. Records of procedure qualification tests. Gas tungsten arc welding of AISI 41XX steels. [4130 and 4142  

Microsoft Academic Search

Procedure WPS-126 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc welding of AISI 4130 and 4142 steel (ASTM A519) (P-No: None), 0.438-inch wall pipe; filler metal is AMS 6457, Class 4130 MC (F-, A-No: None).

C. H. Wodtke; D. R. Frizzell

1986-01-01

177

Selection of Optimum Drilling Parameters on Burr Height Using Response Surface Methodology and Genetic Algorithm in Drilling of AISI 304 Stainless Steel  

Microsoft Academic Search

This article illustrates an application of response surface methodology (RSM) and genetic algorithm (GA) for selecting the optimum combination values of drilling parameters affecting the burr height in drilling of AISI 304 stainless steel. The purpose of this article is to investigate the influence of the cutting parameters, such as cutting speed and feed rate, and point angle on burr

Erol Kilickap; Mesut Huseyinoglu

2010-01-01

178

Improvement of high temperature oxidation resistance of AISI 316L stainless steel by incorporation of Ce–La elements using intense pulsed plasma beams  

Microsoft Academic Search

It is well documented that adding some active elements (such as Y, Ce, La, Er, others) to austenitic stainless steels helps to improve their high temperature oxidation resistance. In the present work we report preliminary results of incorporation of Ce and La into austenitic stainless steel AISI 316L using a new approach based on high intensity pulsed plasma beams. The

J. Piekoszewski; B. Sartowska; M. Barlak; P. Konarski; L. D?browski; W. Starosta; L. Walis; Z. Werner; C. Pochrybniak; K. Bochenska; P. Stoch; W. Szymczyk

2011-01-01

179

Effects of AISI 316L corrosion products in in vitro bone formation.  

PubMed

Rat bone marrow cells were cultured in experimental conditions that favour the proliferation and differentiation of osteoblastic cells (i.e., 2.52 x 10(-4) mol l(-1) ascorbic acid, 10(-2) mol l(-1) beta-glycerophosphate and 10(-8) mol l(-1) dexamethasone) in the absence and in the presence of stainless-steel corrosion products, for a period of 18 days. An AISI 316L stainless-steel slurry (SS) was obtained by electrochemical means and the concentrations of the major metal ions, determined by atomic absorption spectrometry, were 8.78 x 10(-3) mol l(-1) of Fe, 4.31 x 10(-3) mol l(-1) of Cr and 2.56 x 10(-3) mol l(-1) of Ni. Bone marrow cells were exposed to 0.01, 0.1 and 1% of the SS and at the end of the incubation period, control and treated cultures were evaluated by histochemical assays for the identification of the presence of alkaline phosphatase and also calcium and phosphate deposition. Cultures were further observed by scanning electron microscopy. Levels of total and ionised calcium and phosphorus in the culture media collected from control and metal exposed cell cultures were also quantified. Histochemical staining showed that control cultures presented a strong reaction for the presence of alkaline phosphatase and exhibited formation of calcium and phosphates deposits. The presence of 0.01% SS caused no detectable biological effects in these cultures, 0.1% SS impaired osteoblastic behaviour and, 1% SS resulted in cell death. In the absence of bone cells, levels of total and ionised calcium and phosphorus in the control and metal added culture medium were similar throughout the incubation period. A significant decrease in the levels of ionised calcium and phosphorus were observed in the culture medium of control cultures and also in cultures exposed to 0.01% SS after two weeks of incubation, an event related with the formation of mineral calcium phosphate deposits in these cultures. In cultures grown in the presence of 0.1 and 1% SS corrosion products, levels of calcium and phosphorus were similar to those observed in the absence of cells. Results showed that stainless-steel corrosion products above certain concentrations may disturb the normal behaviour of osteoblast-like rat bone marrow cell cultures. PMID:9692798

Morais, S; Sousa, J P; Fernandes, M H; Carvalho, G S; de Bruijn, J D; van Blitterswijk, C A

1998-06-01

180

Surface fatigue life of carburized and hardened M50NiL and AISI 9310 spur gears and rolling-contact test bars  

NASA Technical Reports Server (NTRS)

Spur gear endurance tests and rolling-element surface tests were conducted to investigate vacuum-induction-melted, vacuum-arc-melted (VIM-VAR) M50NiL steel for use as a gear steel in advanced aircraft applications, to determine its endurance characteristics, and to compare the results with those for standard VAR and VIM-VAR AISI 9310 gear material. Tests were conducted with spur gears and rolling-contact bars manufactured from VIM-VAR M50NiL and VAR and VIM-VAR AISI 9310. The gear pitch diameter was 8.9 cm (3.5 in.). Gear test conditions were an inlet oil temperature of 320 K (116 F), and outlet oil temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench rolling-element fatigue tests were conducted at ambient temperatures with a bar speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPA (700 ksi). The VIM-VAR M50NiL gears had a surface fatigue life that was 4.5 and 11.5 times that for VIM-VAR and VAR AISI 9310 gears, respectively. The surface fatigue life of the VIM-VAR M50NiL rolling-contact bars was 13.2 and 21.6 times that for the VIM-VAR and VAR AISI 9310, respectively. The VIM-VAR M50NiL material was shown to have good resistance to fracture through a fatigue spall and to have fatigue life far superior to that of both VIM-VAR and VAR AISI 9310 gears and rolling-contact bars.

Townsend, Dennis P.; Bamberger, Eric N.

1989-01-01

181

Near surface chemistry and corrosion behavior of excimer laser surface-melted AISI type 304 stainless steel  

SciTech Connect

The effects of excimer laser surface melting on the near-surface chemistry, and corrosion behavior of AISI 304 stainless steel have been examined as a function of total energy deposited on the specimen. The surface chemistry resulting from the laser treatments has been examined using Auger electron spectroscopy. Electrochemical methods were used to monitor the corrosion behavior of the specimens in deaerated 0.1 M NaCl. Electron microscopy was used to characterize the extent of local corrosion of the specimens. Laser treatment was observed to increase the chromium concentration of the surface oxide and to reduce the number of pits. Two types of pits were observed on untreated material, but only one type of pit occurred after laser treatment. 7 refs., 5 figs.

Baer, D.R.; Frydrych, D.J.; Jervis, T.R.

1988-05-01

182

Fractographic evaluation of creep effects on strain-controlled fatigue-cracking of AISI 304LC and 316 stainless steel  

NASA Technical Reports Server (NTRS)

Analysis of high temperature low cycle fatigue of AISI 304LC and 316 stainless steels by the method of strainrange partitioning results in four separate strainrange versus life relationships, depending upon the way in which creep-strain and plastic strain are combined within a cycle. Fractography is used in this investigation of the creep-fatigue interaction associated with these cycles. The PP and PC-cycle fractures were transgranular. The PC-cycle resulted in fewer cycles of initiation and shorter total cyclic life for the same applied inelastic strainrange. The CC-cycle had mixed transgranular and intergranular fracture, fewer cycles of initiation and shorter cycle life than PP or PC. The CP-cycle had fully integranular cracking, and failed in fewer cycles than were required for cracks to initate for PP,PC, and CC.

Oldrieve, R. E.

1978-01-01

183

Mechanical behavior of AISI 304SS determined by miniature test methods after neutron irradiation to 28 dpa  

NASA Astrophysics Data System (ADS)

The mechanical properties of AISI 304 stainless steel irradiated for over a decade in the Experimental Breeder Reactor (EBR-II) were measured using miniature mechanical testing methods. The shear punch method was used to evaluate the shear strengths of the neutron-irradiated steel and a correlation factor was empirically determined to predict its tensile strength. The strength of the stainless steel slightly decreased with increasing irradiation temperature, and significantly increased with increasing dose until it saturated above approximately 5 dpa. An effective tensile strain hardening exponent was also obtained from the data which shows a relative decrease in ductility of steel with increased irradiation damage. Ferromagnetic measurements were used to observe and deduce the effects of the stress-induced austenite to martensite transformation as a result of shear punch testing.

Rabenberg, Ellen M.; Jaques, Brian J.; Sencer, Bulent H.; Garner, Frank A.; Freyer, Paula D.; Okita, Taira; Butt, Darryl P.

2014-05-01

184

Evaluation of Microstructure and Toughness of AISI D2 Steel by Bright Hardening in Comparison with Oil Quenching  

NASA Astrophysics Data System (ADS)

AISI D2 is used widely in the manufacture of blanking and cold-forming dies, on account of its excellent hardness and wear behavior. Increasing toughness at a fixed high level of hardness is growing requirement for this kind of tool steel. Improving microstructure characteristics, especially refinement of coarse carbides, is an appropriate way to meet such requirement. In this study, morphology and size of carbides in martensite matrix were compared between two kinds of samples, which were bright hardened (quenching in hot alkaline salt bath consisting of 60% KOH and 40% NaOH) at 230 °C and quenched in oil bath at 60 °C. Results showed that morphology and distribution of carbides in samples performed by bright hardening were finer and almost spherical compared to that of oil quenched. This microstructure resulted in an improvement in toughness and tensile properties of alloy.

Torkamani, H.; Raygan, Sh.; Rassizadehghani, J.

2011-12-01

185

Effect of flowing sodium on corrosion and tensile properties of AISI type 316LN stainless steel at 823 K  

NASA Astrophysics Data System (ADS)

AISI type 316LN stainless steel was exposed to flowing sodium in mass transfer loop (MTL) at 823 K for 16 000 h and then examined for changes in the tensile properties due to the mass transfer and corrosion effects. Comparisons in microstructural and mechanical properties were made between annealed, thermally aged and sodium exposed materials. Microstructural examination of thermally aged and sodium exposed materials revealed precipitation of carbides at the grain boundaries. The sodium exposed samples contained a degraded layer at the surface up to a depth of around 10 ?m and a surface carburized layer of about 30 ?m. There was about 15% increase in yield strength and a decrease of about 20% in ductility for the sodium exposed material vis-a-vis thermally aged material and this was attributed to carburization effects and microstructural changes.

Sivai Bharasi, N.; Thyagarajan, K.; Shaikh, H.; Balamurugan, A. K.; Bera, Santanu; Kalavathy, S.; Gurumurthy, K.; Tyagi, A. K.; Dayal, R. K.; Rajan, K. K.; Khatak, H. S.

2008-07-01

186

Experimental comparison of carbon-dioxide and liquid nitrogen cryogenic coolants in turning of AISI 1045 steel  

NASA Astrophysics Data System (ADS)

This experimental work is carried out to investigate the performance and influence of cryogenic coolants such as CO2 (carbon dioxide) and LN2 (liquid nitrogen) on cutting temperature, cutting force, tool wear, surface finish and chip morphology in machining of AISI 1045 steel compared to wet machining. The results proved that the application of cryogenic coolants reduced the cutting temperature drastically which resulted in appreciable improvement in surface finish of the product and reduced tool wear. The use of cryogenic LN2 reduced the cutting temperature about 3-17% when compared to CO2 coolant. Application of CO2 reduced the cutting forces and improved the surface finish of the machined part to an extent about 2-12% and 2-14% respectively when compared to the use of cryogenic LN2 coolant. Tool wear was found to be less on the application of CO2 compared to the wet and LN2 machining conditions.

Dilip Jerold, B.; Pradeep Kumar, M.

2012-10-01

187

Application of Strainrange Partitioning to the prediction of creep-fatigue lives of AISI Types 304 and 316 stainless steel  

NASA Technical Reports Server (NTRS)

As a demonstration of the predictive capabilities of the method of Strainrange Partitioning, published high-temperature, low cycle, creep-fatigue test results on AISI Types 304 and 316 stainless steel were analyzed and calculated cyclic lives compared with observed lives. Predicted lives agreed with observed lives within factors of two for 76 percent, factors of three for 93 percent, and factors of four for 98 percent of the laboratory tests analyzed. Agreement between observed and predicted lives is judged satisfactory considering that the data are associated with a number of variables (two alloys, several heats and heat treatments, a range of temperatures, different testing techniques, etc.) that are not directly accounted for in the calculations.

Saltsman, J. F.; Halford, G. R.

1977-01-01

188

Application of strainrange partitioning to the prediction of creep-fatigue lives of AISI types 304 and 316 stainless steel  

NASA Technical Reports Server (NTRS)

As a demonstration of the predictive capabilities of the method of Strainrange Partitioning, published high-temperature, low cycle, creep-fatigue test results on AISI Types 304 and 316 stainless steel were analyzed and calculated, cyclic lives compared with observed lives. Predicted lives agreed with observed lives within factors of two for 76 percent, factors of three for 93 percent, and factors of four for 98 percent of the laboratory tests analyzed. Agreement between observed and predicted lives is judged satisfactory considering that the data are associated with a number of variables (two alloys, several heats and heat treatments, a range of temperatures, different testing techniques, etc.) that are not directly accounted for in the calculations.

Saltsman, J. F.; Halford, G. R.

1976-01-01

189

Quantifying Cutting and Wearing Behaviors of TiN- and CrN-Coated AISI 1070 Steel  

PubMed Central

Hard coatings such as titanium nitride (TiN) and chromium nitride (CrN) are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP) technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM), line scan analyses and X-ray diffraction (XRD). The wear properties of TiN- and CrN-coated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples.

Cakan, Ahmet; Ozkaner, Vedat; Yildirim, Mustafa M.

2008-01-01

190

Life time calculations for LCF loading combined with tensional hold periods. Application to Zircaloy-4 and AISI 304  

NASA Astrophysics Data System (ADS)

The life time in high amplitude strain cycling with tensional hold periods is analysed presuming that creep failure damage is life determining. The life fraction rule (LFR) is used to calculate the life time consumpted during the dwell period in strain controlled tests as well as during tensional hold time stress cycles. It follows from the present investigation that stress relaxation occurring during the strain hold periods plays the dominant influence upon the relationship between life and dwell time. For strong stress relaxation (e.g. high temperature) less damage is accumulated as compared to suppressed relaxation (low temperature). The damage in stress relaxation is calculated by means of the LFR and the results are compared to experiments conducted on Zircaloy-4 and the austenitic stainless steel Type AISI 304. From the very good agreement between both it is concluded that under the loading conditions considered, creep failure damage is the main life determining damage contribution.

Bo?ek, M.; Armas, A.; Piel, D.

1983-04-01

191

Comparison of Austenite Decomposition Models During Finite Element Simulation of Water Quenching and Air Cooling of AISI 4140 Steel  

NASA Astrophysics Data System (ADS)

An indigenous, non-linear, and coupled finite element (FE) program has been developed to predict the temperature field and phase evolution during heat treatment of steels. The diffusional transformations during continuous cooling of steels were modeled using Johnson-Mehl-Avrami-Komogorov equation, and the non-diffusion transformation was modeled using Koistinen-Marburger equation. Cylindrical quench probes made of AISI 4140 steel of 20-mm diameter and 50-mm long were heated to 1123 K (850 °C), quenched in water, and cooled in air. The temperature history during continuous cooling was recorded at the selected interior locations of the quench probes. The probes were then sectioned at the mid plane and resultant microstructures were observed. The process of water quenching and air cooling of AISI 4140 steel probes was simulated with the heat flux boundary condition in the FE program. The heat flux for air cooling process was calculated through the inverse heat conduction method using the cooling curve measured during air cooling of a stainless steel 304L probe as an input. The heat flux for the water quenching process was calculated from a surface heat flux model proposed for quenching simulations. The isothermal transformation start and finish times of different phases were taken from the published TTT data and were also calculated using Kirkaldy model and Li model and used in the FE program. The simulated cooling curves and phases using the published TTT data had a good agreement with the experimentally measured values. The computation results revealed that the use of published TTT data was more reliable in predicting the phase transformation during heat treatment of low alloy steels than the use of the Kirkaldy or Li model.

Babu, K.; Prasanna Kumar, T. S.

2014-08-01

192

Prevention of crevice corrosion of AISI 304 stainless steel in sea water by local laser surface cladding  

SciTech Connect

AISI 304 stainless steels suffer severe crevice corrosion, within the crevices under bolt and lap joints and surface rivet heads and other shielded areas caused by holes, gasket surfaces, lap joints and surface deposit, in the sea water. To prevent this kind of corrosion, Fe-30Cr-4Mo and Fe-19Cr-18Ni-6Mo-0.2N coatings were deposited on these areas on the steels by laser surface cladding. The microstructure and chemical composition of the coatings were studied with optical and electron microscopy, x-ray diffraction and electron probe microanalysis. Fe-30Cr-4Mo coating consists of ferrite fine dendrites with slight segregation of Cr and Mo at dendrite boundaries and Fe-19Cr-18Ni-6Mo-0.2N coating consists of austenite fine dendrites also with slight segregation of Cr and Mo at dendrite boundaries. Crevice corrosion resistance of the coatings was evaluated with electrochemical method (Wilde`s method) and free immersion tests in artificial sea water and 10wt% FeCl{sub 3}. Results of electrochemical tests show that Fe-30Cr-4Mo and Fe-19Cr-18Ni-6Mo-0.2N coatings have much better crevice corrosion resistance than commercial AISI 304 stainless steel. After immersed in artificial sea water for 2 months, laser surface cladded samples did not suffer any crevice corrosion whereas untreated samples suffered severe crevice corrosion. After immersed in 10wt% FeCl{sub 3} for 2 months, crevice corrosion started on both Fe-30Cr-4Mo and Fe-19Cr-18Ni-6Mo-0.2N coatings.

Li, R.; Feng, J.; Ferreira, M.G.S. [Technical Univ. of Lisbon (Portugal)] [and others

1996-12-31

193

Influence of dissolved hydrogen on the fatigue crack growth behaviour of AISI 4140 steel  

NASA Astrophysics Data System (ADS)

Many metallic structural components come into contact with hydrogen during manufacturing processes or forming operations such as hot stamping of auto body frames and while in service. This interaction of metallic parts with hydrogen can occur due to various reasons such as water molecule dissociation during plating operations, interaction with atmospheric hydrogen due to the moisture present in air during stamping operations or due to prevailing conditions in service (e.g.: acidic or marine environments). Hydrogen, being much smaller in size compared to other metallic elements such as Iron in steels, can enter the material and become dissolved in the matrix. It can lodge itself in interstitials locations of the metal atoms, at vacancies or dislocations in the metallic matrix or at grain boundaries or inclusions (impurities) in the alloy. This dissolved hydrogen can affect the functional life of these structural components leading to catastrophic failures in mission critical applications resulting in loss of lives and structural component. Therefore, it is very important to understand the influence of the dissolved hydrogen on the failure of these structural materials due to cyclic loading (fatigue). For the next generation of hydrogen based fuel cell vehicles and energy systems, it is very crucial to develop structural materials for hydrogen storage and containment which are highly resistant to hydrogen embrittlement. These materials should also be able to provide good long term life in cyclic loading, without undergoing degradation, even when exposed to hydrogen rich environments for extended periods of time. The primary focus of this investigation was to examine the influence of dissolved hydrogen on the fatigue crack growth behaviour of a commercially available high strength medium carbon low alloy (AISI 4140) steel. The secondary objective was to examine the influence of microstructure on the fatigue crack growth behaviour of this material and to determine the hydrogen induced failure mechanism in this material during cyclic loading. The secondary objective of this investigation was to determine the role of inclusions and their influence in affecting the fatigue crack growth rate of this material. Compact tension and tensile specimens were prepared as per ASTM E-647, E-399 and E-8 standards. The specimens were tested in three different heat treated conditions i.e. annealed (as received) as well as two austempered conditions. These specimens were precharged with hydrogen (ex situ) using cathodic charging method at a constant current density at three different time periods ranging from 150 to 250 hours before conducting fatigue crack growth tests. Mode 1 type fatigue tests were then performed in ambient atmosphere at constant amplitude using load ratio R of 0.1. The near threshold fatigue crack growth rate, fatigue threshold and the fatigue crack growth rate in the linear region were determined. Fatigue crack growth behaviour of specimens without any dissolve hydrogen were then compared with the specimens with different concentration of dissolved hydrogen. The test results show that the dissolved hydrogen concentration increases with the increase in charging time in all three heat treated conditions and the hydrogen uptake shows a strong dependence on the microstructure of the alloy. It was also observed that the microstructure has a significant influence of on the fatigue crack growth and SCC behaviour of the alloy with dissolved hydrogen. As the dissolved hydrogen concentration increases, the fatigue threshold was found to decrease and the near threshold crack growth rate increases in all three heat treated conditions showing the deleterious effect of hydrogen, but to a different extent in each condition. Current test results also indicate that the fatigue crack growth rates in the linear region increases as the dissolved hydrogen content increases in all three heat treated conditions. It is also observed that increasing the austempering temperature decreases the resistance to hydrogen embrittlement. An interesting p

Ramasagara Nagarajan, Varun

194

Initial Symptoms of ALS  

MedlinePLUS

Home About ALS About Us Our Research In Your Community Advocate Help fight ALS Donate About ALS What is ALS? Facts You Should Know Who does ALS affect? Diagnosing ALS Symptoms Forms of ALS Genetic ...

195

Hydrogen Uptake Enhancement and Accelerated Hydrogen Re-embrittlement of Cd-plated AISI 4340 Steel Bolts Coupled with IN718 Nuts  

NASA Astrophysics Data System (ADS)

Hydrogen re-embrittlement on anodically coated high strength steels could be of great concern because the uptake of hydrogen from the corrosion process can cause component failure. A scratched Cd-coated AISI 4340 steel membrane has been coupled with different materials reproducing crevice conditions, and the hydrogen uptake has been measured using a modified Devanathan-Stachurski permeation apparatus. Experimental tests proved that, in presence of a crevice, metals nobler than cadmium strongly enhance local hydrogen reduction on exposed steel areas, thus possibly favoring brittle failure of high strength steel components during service. Therefore, the coupling of uncoated nuts made of noble passive alloys (like Inconel) to Cd-plated AISI 4340 steel bolts should be avoided.

Lovicu, Gian Franco; Colombo, Costanza; de Sanctis, Massimo; Valentini, Renzo

2011-12-01

196

Studies on the influence of metallurgical variables on the stress corrosion behavior of aisi 304 stainless steel in sodium chloride solution using the fracture mechanics approach  

Microsoft Academic Search

Stress corrosion data on a nuclear grade AISI type 304 stainless steel in a boiling solution of 5M NaCl+ 0.15M Na2SO4+ 3 mL\\/L HC1 (bp 381 K) for various metallurgical conditions of the steel are presented in this article. The metallurgical conditions used are solution annealing, sensitization, 10 pct cold work, 20 pct cold work, solution annealing + sensitization, 10

H. S. Khatak; J. B. Gnanamoorthy; P. Rodriguez

1996-01-01

197

Studies on the influence of metallurgical variables on the stress corrosion behavior of aisi 304 stainless steel in sodium chloride solution using the fracture mechanics approach  

Microsoft Academic Search

Stress corrosion data on a nuclear grade AISI type 304 stainless steel in a boiling solution of 5M NaCl+ 0.15M Na2SO4+ 3 mL\\/L HC1 (bp 381 K) for various metallurgical conditions of the steel are presented in this article. The metallurgical\\u000a conditions used are solution annealing, sensitization, 10 pct cold work, 20 pct cold work, solution annealing + sensitization,\\u000a 10

H. S. Khatak; J. B. Gnanamoorthy; P. Rodriguez

1996-01-01

198

Effect of Mo and Mn additions on the corrosion behaviour of AISI 304 and 316 stainless steels in H 2SO 4  

Microsoft Academic Search

The work addresses the influence of Mn and Mo additions on corrosion resistance of AISI 304 and 316 stainless steels in 30wt.% H2SO4 at 25 and 50°C. Corrosion mechanism was determined by gravimetric tests, DC polarization measurements and electrochemical impedance spectroscopy (EIS). The morphology and nature of the reaction products formed on the material surface were analysed by scanning electron

A. Pardo; M. C. Merino; A. E. Coy; F. Viejo; R. Arrabal; E. Matykina

2008-01-01

199

Study on welding such dissimilar materials as AISI 304 stainless steel and DHP copper in a sea-water environment. Influence of weld metals on corrosion  

Microsoft Academic Search

This work determines which material performs best according to its specific properties, by means of welding joints and evaluating the different welding processes and weld metals employed, considering their mechanical performance and resistance to sea-water corrosion. The base materials were butt-welded to produce 1.5 mm thick test pieces of AISI 304 stainless steel and copper, and de-oxidized in DHP phosphorus,

E. Zumelzu; C. Cabezas

1996-01-01

200

A comparative study of the wear behaviour of sintered and laser surface melted AISI M42 high speed steel diluted with iron  

Microsoft Academic Search

Powders of AISI M42 high-speed steel (HSS) were blended with different proportions of water-atomised iron powders. The powders were subsequently submitted to uniaxial pressing and then divided in three lots. The first was submitted to sintering, the second was submitted to sintering plus laser surface melting (LSM) and the third was submitted to sintering plus LSM plus double tempering at

R. Colaço; E. Gordo; E. M. Ruiz-Navas; M. Otasevic; R. Vilar

2006-01-01

201

Solid-state diffusion welding of wrought AISI 304 stainless steel to Nimonic AP1 superalloy powder by hot isostatic pressing  

Microsoft Academic Search

The diffusion welding characteristics of wrought AISI 304 stainless steel to a superalloy powder Nimonic AP-1 were examined in this study. After encapsulation, evacuation and degassing, the welds were hot isostatically pressed (HIPed) in two different cycles, i.e., 1,200 C (2,192 F)\\/3h\\/147 MPa and 1,270 C (2,318 F)\\/3h\\/121 MPa. A variation in surface condition of stainless steel was also studied

M. C. Somani; N. C. Birla; A. Tekin

1998-01-01

202

An evaluation of heat partition in the high-speed turning of AISI\\/SAE 4140 steel with uncoated and TiN-coated tools  

Microsoft Academic Search

In manufacturing by machining, thermal loads on cutting tools can have a major influence on tool wear and hence process cost, especially at higher cutting speeds. An investi- gation has been undertaken to determine heat partition into the cutting tool for high-speed machining of AISI\\/SAE 4140 high-strength alloy steel with uncoated and TiN-coated tools. The cutting tests have been performed

F Akbar; P T Mativenga; M A Sheikh

2008-01-01

203

Influence of Cu and Sn content in the corrosion of AISI 304 and 316 stainless steels in H 2SO 4  

Microsoft Academic Search

This paper addresses the influence of Cu and Sn addition on the corrosion resistance of AISI 304 and 316 stainless steels in 30wt% H2SO4 at 25 and 50°C. The corrosion process was evaluated by gravimetric tests, DC measurements and electrochemical impedance spectroscopy (EIS). The corrosion products were analysed by SEM, X-ray mapping and XPS before and after accelerated tests. The

A. Pardo; M. C. Merino; M. Carboneras; F. Viejo; R. Arrabal; J. Muñoz

2006-01-01

204

Corrosion properties of plasma nitrided AISI 410 martensitic stainless steel in 3.5% NaCl and 1% HCl aqueous solutions  

Microsoft Academic Search

Samples of an AISI 410 martensitic stainless steel were plasma nitrided at a temperature of 420°C, 460°C or 500°C for 20h. The composition, microstructure and hardness of the nitrided samples were characterised using a variety of analytical techniques. In particular, the corrosion properties of the untreated and plasma nitrided samples were evaluated using anodic polarisation tests in 3.5% NaCl solution

C. X. Li; T. Bell

2006-01-01

205

Effect of different environmental parameters on pitting behavior of AISI type 316L stainless steel: Experimental studies and neural network modeling  

Microsoft Academic Search

AISI type 316L stainless steel was subjected to electrochemical polarization tests in an aqueous environment of varying chloride ion concentration (17,500–70,000ppm), pH (1.23–5.0) and temperature (298–333K). Values of critical pitting potentials (Epit) were determined from the polarization tests. Increasing concentration and temperature, and decreasing pH were found to decrease the Epit. Eighty values of Epit, at different chloride concentrations, pH

K. V. S. Ramana; T. Anita; Sumantra Mandal; S. Kaliappan; H. Shaikh; P. V. Sivaprasad; R. K. Dayal; H. S. Khatak

2009-01-01

206

Welding procedure specification. Supplement 1. Records of procedure qualification tests. Gas tungsten arc and shielded metal arc welding of AISI 41XX steels. [4130 and 4142 steels  

SciTech Connect

Procedure WPS-127 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc and shielded metal arc welding of AISI 4130 and 4142 steels (ASTM A519) (P-No: None), 0.438-inch wall pipe; filler metal is AMS 6457, Class 4130 MC (F-, A-No: None) (GTAW) and E8018-B2L (F-4, A-3) (GMAW): shielding gas is argon (GTAW).

Wodtke, C.H.; Frizzell, D.R.

1986-06-01

207

Welding procedure specification. Supplement 1. Records of procedure qualification tests. Gas tungsten arc and shielded metal arc welding of AISI 41XX steels. [4130 and 4142 steels  

Microsoft Academic Search

Procedure WPS-127 is qualified under Section IX of the ASME Boiler and Pressure Vessel Code for gas tungsten arc and shielded metal arc welding of AISI 4130 and 4142 steels (ASTM A519) (P-No: None), 0.438-inch wall pipe; filler metal is AMS 6457, Class 4130 MC (F-, A-No: None) (GTAW) and E8018-B2L (F-4, A-3) (GMAW): shielding gas is argon (GTAW).

C. H. Wodtke; D. R. Frizzell

1986-01-01

208

Soft X-ray absorption spectroscopy study of the effects of Si, Ce, and Mo ion implantation on the passive layer of AISI 304 stainless steel  

Microsoft Academic Search

The chemical modifications introduced in the passive layer of AISI 304 stainless steel after Si, Ce, and Mo ion implantation were investigated and compared with non-implanted steel by soft X-ray absorption spectroscopy. The influence of ion implantation on the passive properties was evaluated by measuring soft X-ray absorption spectra at the Cr, Fe, Ni, Mn and Si 2p in addition

M. F. López; A. Gutiérrez; F. J. Pérez; M. P. Hierro; F. Pedraza

2003-01-01

209

Al Composites  

NASA Astrophysics Data System (ADS)

In the present study, cold spraying technique was used to fabricate a metal matrix composite (MMC) that consists of Ni matrix and 20 vol.% Ni3Al particles at two different particle sizes as reinforcement. This study intends to investigate the effect of reinforcement particle size on microstructural and mechanical properties of cold sprayed MMCs. Two different Ni3Al powders with nominal particle size of -45 to +5 and +45 to 100 ?m were used as reinforcement in this study. Cold sprayed Ni-Ni3Al samples were subjected to the microstructural observation and characterization prior to any mechanical testing. Then, samples were tested using nano-indentation, Knoop hardness, Vickers hardness, and Resonance frequency to evaluate their mechanical properties. No significant changes were observed in microstructural characteristics due to different particle sizes. The results obtained from a variety of mechanical testings indicated that the increasing reinforcement particle size resulted in the slight reduction of mechanical properties such as elastic modulus and hardness in cold sprayed MMCs. The mechanical interlock between deposited particles defines the bonding strength in cold sprayed samples. Small size particles have a higher velocity and impact resulting in stronger interlock between deformed particles.

Chandanayaka, Tharaka; Azarmi, Fardad

2014-05-01

210

Biocompatibility studies of low temperature nitrided and collagen-I coated AISI 316L austenitic stainless steel.  

PubMed

The biocompatibility of austenitic stainless steels can be improved by means of surface engineering techniques. In the present research it was investigated if low temperature nitrided AISI 316L austenitic stainless steel may be a suitable substrate for bioactive protein coating consisting of collagen-I. The biocompatibility of surface modified alloy was studied using as experimental model endothelial cells (human umbilical vein endothelial cells) in culture. Low temperature nitriding produces modified surface layers consisting mainly of S phase, the supersaturated interstitial solid solution of nitrogen in the austenite lattice, which allows to enhance surface microhardness and corrosion resistance in PBS solution. The nitriding treatment seems to promote the coating with collagen-I, without chemical coupling agents, in respect of the untreated alloy. For biocompatibility studies, proliferation, lactate dehydrogenase levels and secretion of two metalloproteinases (MMP-2 and MMP-9) were determined. Experimental results suggest that the collagen protection may be favourable for endothelial cell proliferation and for the control of MMP-2 release. PMID:23471501

Martinesi, M; Stio, M; Treves, C; Borgioli, F

2013-06-01

211

Effects of strain and strain-induced ?'-martensite on passive films in AISI 304 austenitic stainless steel.  

PubMed

In this paper, the effects of strain and heat treatment on strain-induced ?'-martensite of AISI 304 stainless steel tubes were measured by X-ray diffraction. Moreover, the effects of strain and content of ?'-martensite on passivated property on the surface of the material in borate buffer solution were evaluated by electrochemical technique. The results showed that the volume fraction of ?'-martensite increased gradually with the increase of tensile strain for as-received and solid solution samples. However, ?'-martensite in as-received sample was more than that in the solid solution sample. The electrochemical impedance spectroscopy results showed that the solid solution treatment improved corrosion resistance of the steel, especially for samples with small strain. Moreover, acceptor densities were always higher than donor densities for as-received and solid solution samples. With the increase of strain, the increase tendency of acceptor density was more significant than that of donor density. We also found that the total density of the acceptor and donor almost increased linearly with the increase of ?'-martensite. The present results indicated that the increased acceptor density might lead to the decreased corrosion resistance of the steel. PMID:24268285

Lv, Jinlong; Luo, Hongyun

2014-01-01

212

Effect of Ball Burnishing Process on the Surface Quality and Microstructure Properties of AISI 1010 Steel Plates  

NASA Astrophysics Data System (ADS)

A newly developed ball burnishing tool was designed and tested for surface finishing of large flat surfaces in a shortest possible time. Optimization and analysis of the burnishing process were carried on AISI 1010 steel hot-rolled plates using the Taguchi technique and response surface methodology (RSM) to identify the effect of burnishing parameters (i.e., burnishing speed, burnishing force, and feed rate) on surface roughness, surface hardness, and microstructure of burnished surfaces. The optimal burnishing parameters were found after conducting the Taguchi's L25 matrix experiments and obtaining the response models for the surface roughness and the hardness. It was found that the burnishing force has the most influential effect on the surface roughness and hardness, followed by the burnishing speed, and least influence by the feed rate. In addition, microstructural examinations of the burnished surface indicate that burnishing force more than 400 N causes flaking of the burnished surfaces. The optimal burnishing parameters for the steel plates were a combination of a burnishing speed of 235 rpm, a burnishing force of 400 N, and a feed rate of 0.18 mm/rev. Using these parameters, the mean surface roughness has been improved from Ra = 2.48 to 1.75 ?m, while the hardness increases from 59 to 65.5 HRB.

Gharbi, F.; Sghaier, S.; Al-Fadhalah, K. J.; Benameur, T.

2011-08-01

213

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

NASA Astrophysics Data System (ADS)

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.

Kahrobaee, Saeed; Kashefi, Mehrdad

2015-03-01

214

Exploration of surface hydrophilic properties on AISI 304 stainless steel and silicon wafer against aging after atmospheric pressure plasma treatment  

NASA Astrophysics Data System (ADS)

The aim of this work is to seek the enhanced surface hydrophilic properties on AISI 304 stainless steel and silicon wafer after atmospheric pressure plasma treatment using a specifically designed atmospheric pressure plasma jet. The aging tendency of surface hydrophilic property under air is highlighted. It is concluded that both of the silicon wafer and stainless steel treated with plasma generated from supply gas of argon 15 slm mixed with oxygen 40 sccm shows a better tendency on remaining high water contact angle as compared to that with pure argon and nitrogen addition. Additional peaks of O I (777, 844 nm), O II (408 nm) are detected by optical emission spectroscope indicating the presence of the oxygen radicals and ionic species, which interact with surfaces and thus contribute to low water contact angle (WCA) surfaces. Moreover, the result acquired from X-ray photoelectron spectroscopy (XPS) indicates that the increase in the oxygen-related bonding exhibits a better contribution on remaining high surface energy over a period of time.

Chuang, Shang-I.; Duh, Jenq-Gong

2014-11-01

215

The effect of Zr-implantation on the thermal oxidation and aqueous corrosion of AISI 321 stainless steel  

NASA Astrophysics Data System (ADS)

The effect of Zr-implantation (energy: 40 keV, dose: 1 × 10 17 ions/cm 2) on the oxidation of AISI 321 austenitic stainless steel (Fe/Cr18/Ni8/Ti) has been studied at temperatures of 450, 550 and 650°C, in air. The duration of the oxidation was varied between one and six days. The oxygen distribution on the oxidized samples has been determined using the 16O(d, p) 17O nuclear reaction whereas the zirconium depth profile by means of Rutherford backscattering spectroscopy (RBS) using ?-particles as projectiles. X-ray photoelectron spectroscopy (XPS) was used as support to these measurements. The morphology and the surface microstructure of the specimens were investigated by scanning electron and scanning transmission electron microscopy (SEM and STEM). The evaluation of the data has indicated that the implantation of Zr-ions leads to a chromium depletion in the near-surface layers and enhances the oxidation of the implanted samples compared to the initial material. Electrochemical experiments of the Zr-implanted steel performed in 1N sulphuric acid solution (H 2SO 4 1N) showed an increase of the corrosion resistance.

Noli, F.; Misaelides, P.; Giorginis, G.; Baumann, H.; Hatzidimitriou, A.

1995-02-01

216

Formation mechanism of micro-spikes on AISI 4340 steel with femtosecond laser pulses at near-threshold fluence  

NASA Astrophysics Data System (ADS)

We report on the mechanism for the formation of conical micro-spikes on an AISI 4340 steel surface under femtosecond irradiation at near-threshold fluence and at a high repetition rate. We establish that the conical micro-spikes formed in this way are unique and result from a completely different formation mechanism compared to previously reported formations which are characterized by a random evolution of re-condensed oxide particulates. An experimental micro-spike formation map demonstrates how random micro-spike formations progress to uniform micro-spikes as the fluence increases and how the scan-speed affects the size of the spikes. Apart from fluence, we show that a change in focal position can help to fine-tune the energy density, resulting in identical random conical micro-spikes. The fabricated surfaces show an extraordinary absorption coefficient of up to 0.91 resulting from multiple reflections in the valleys between the micro-spikes. Finally, we find that the relationship between cone number density and scan speed for near-threshold fluence is caused by reduced heat accumulation, increasing the survival rate of cone formation sites.

Kam, Dong-Hyuck; Kim, Jedo; Song, Lijun; Mazumder, Jyoti

2015-04-01

217

Cobalt-Free Laser Cladding on AISI Type 316L Stainless Steel for Improved Cavitation and Slurry Erosion Wear Behavior  

NASA Astrophysics Data System (ADS)

Laser cladding of Colmonoy-5 (a nickel base alloy) and Metco-41C (an iron base alloy) on AISI type 316L stainless steel (SS316L) and their wear behaviors were investigated to establish Co-free clad layers for potential applications in nuclear industry. A 3.5 kW CO2 laser-based system was used to optimize the laser cladding on SS316L substrate. The observed optimum parameters were: laser power of 1.6 kW, scan speed of 0.6 m/min, and powder feed rate of 8 g/min with 60% overlapping. The microstructure studies revealed that the clad layers primarily comprise very fine columnar dendritic structures, while clad-substrate interface exhibited planar and non-epitaxial mode of solidification due to high cooling rates. The cavitation and slurry erosion behaviors of laser clad layers were also compared to that of Stellite-6 for potential direct replacement. The cavitation erosion resistance was improved by a factor of 1.6, 3.7, and 4.1, while the slurry erosion resistances at an impingement angle of 30° were 1.5, 4.8, and 1.8 times better for laser clad surfaces of Colmonoy-5, Metco-41C, and Stellite-6, respectively, as compared to that of bare SS316L substrate. The study demonstrated that Metco-41C is a better choice as Co-free clad material for potential nuclear applications.

Paul, C. P.; Gandhi, B. K.; Bhargava, P.; Dwivedi, D. K.; Kukreja, L. M.

2014-12-01

218

Distributions of Cr depletion levels in sensitized AISI 304 stainless steel and its implications concerning intergranular corrosion phenomena  

SciTech Connect

An electrochemical method has been employed to obtain the population distribution of minimum grain boundary Cr concentrations for sensitized AISI 304 stainless steel (S30400). The detailed information about the extent of Cr depletion provided by the distribution is compared to the average degree of sensitization (DOS) evaluated by the standard and a modified single loop-electrochemical potentiokinetic reactivation (SL-EPR) technique. The distribution of Cr levels on a grain by grain basis is shown to provide information about intergranular stress corrosion cracking (IGSCC) susceptibility that cannot be provided by EPR methods. Sensitized 304SS tested in an environment relevant to nuclear reactors has been shown to fail by IGSCC when the grain boundary Cr concentration is depleted to below a critical level of {approx}13.5%. In a separate study, it has been shown that more than 23% of the grain boundaries must be depleted to the relevant critical level in order to observe macroscopically brittle behavior. The present study combines these two criteria and defines a sensitized material`s IGSCC susceptibility by revealing the extent of Cr depletion as well as the quantity of depleted grain boundaries.

Gaudett, M.A.; Scully, J.R. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science and Engineering

1993-12-01

219

Nano-Borides and Silicide Dispersed Composite Coating on AISI 304 Stainless Steel by Laser-Assisted HVOF Spray Deposition  

NASA Astrophysics Data System (ADS)

The study concerned a detailed microstructural investigation of nano-borides (Cr2B and Ni3B) and nano-silicide (Ni2Si) dispersed ?-nickel composite coating on AISI 304 stainless steel by HVOF spray deposition of the NiCrBSi precursor powder and subsequent laser surface melting. A continuous wave diode laser with an applied power of 3 kW and scan speed of 20 mm/s in argon shroud was employed. The characterization of the surface in terms of microstructure, microtexture, phases, and composition were carried out and compared with the as-coated (high-velocity oxy-fuel sprayed) surface. Laser surface melting led to homogenization and refinement of microstructures with the formation of few nano-silicides of nickel along with nano-borides of nickel and chromium (Ni3B, Cr2B, and Cr2B3). A detailed microtexture analysis showed the presence of no specific texture in the as-sprayed and laser-melted surface of Cr2B and Ni3B phases. The average microhardness was improved to 750-900 VHN as compared to 250 VHN of the as-received substrate. Laser surface melting improved the microhardness further to as high as 1400 VHN due to refinement of microstructure and the presence of silicides.

Sharma, Prashant; Majumdar, Jyotsna Dutta

2014-10-01

220

Correlation between surface physicochemical properties and the release of iron from stainless steel AISI 304 in biological media.  

PubMed

Stainless steel is widely used in biological environments, for example as implant material or in food applications, where adsorption-controlled ligand-induced metal release is of importance from a corrosion, health, and food safety perspective. The objective of this study was to elucidate potential correlations between surface energy and wettability of stainless steel surfaces and the release of iron in complexing biological media. This was accomplished by studying changes in surface energies calculated from contact angle measurements, surface oxide composition (X-ray photoelectron spectroscopy), and released iron (graphite furnace atomic absorption spectroscopy) for stainless steel grade AISI 304 immersed in fluids containing bovine serum albumin or citric acid, and non-complexing fluids such as NaCl, NaOH, and HNO3. It was shown that the surface wettability and polar surface energy components were all influenced by adventitious atmospheric carbon (surface contamination of low molecular weight), rather than differences in surface oxide composition in non-complexing solutions. Adsorption of both BSA and citrate, which resulted in ligand-induced metal release, strongly influenced the wettability and the surface energy, and correlated well with the measured released amount of iron. PMID:25048358

Hedberg, Yolanda; Karlsson, Maria-Elisa; Blomberg, Eva; Odnevall Wallinder, Inger; Hedberg, Jonas

2014-10-01

221

Influence of Sigma Phase on Pitting Resistance Depending on Solidification Mode in AISI316L Weld Metal  

NASA Astrophysics Data System (ADS)

The pitting corrosion resistances were investigated in the AISI 316L stainless steel weld metals with respect to the sigma phase precipitation in a 0.1 M NaCl solution. The modified flux-cored arc welding filler wires were fabricated at various chromium and nickel equivalent ratios using the flux-cored arc welding process. As the Cr/Ni equivalent ratio increased, the precipitated ? phase content increased in the temperature range of 923 K to 1123 K (650 °C to 850 °C), and the specimen that was aged at 1123 K (850 °C) precipitated the ? phase rapidly. The hardness increased with increasing sigma contents. During the potentiodynamic anodic polarization test, the specimens that were aged at 923 K to 1123 K (650 °C to 850 °C) exhibited lower pitting potentials than the as-weld metal. Additionally, the specimens that were aged for longer times exhibited lower pitting potentials. The pits occurred preferentially in the ductility dip cracking in specimen 1, whereas intergranular pits occurred in the sigma phase regions along the vermicular ferrite and acicular ferrite grain boundaries in specimens 2 and 3.

Jang, A. Y.; Lee, H. W.

2012-06-01

222

An experimental study of uniaxial creep, cyclic creep and relaxation of aisi type 304 stainless steel at room temperature  

NASA Astrophysics Data System (ADS)

FOLLOWING previous work ( KREMPL, 1979), a servocontrolled testing machine and strain measurement at the gage length were used to study the uniaxial rate(time)-dependent behavior of AISI Type 304 stainless steel at room temperature. The test results show that the creep strain accumulated in a given period of time depends strongly on the stress-rate preceding the creep test. In constant stress-rate zero-to-tension loading the creep strain accumulated in a fixed time-period at a given stress level is always higher during loading than during unloading. Continued cycling causes an exhaustion of creep ratchetting which depends on the stress-rate. Periods of creep and relaxation introduced during completely reversed plastic cycling show that the curved portions of the hysteresis loop exhibit most of the inelasticity. In the straight portions, creep and relaxation are small and there exists a region commencing after unloading where the behavior is similar to that at the origin for virgin materials. This region does not extend to zero stress. The results are at variance with creep theory and with viscoplasticity theories which assume that the yield surface expands with the stress. They support the theory of viscoplasticity based on total strain and overstress.

Kujawski, D.; Kallianpur, V.; Krempl, E.

1980-04-01

223

The interaction of cyclic hardening and ratchetting for AISI type 304 stainless steel at room temperature—I. Experiments  

NASA Astrophysics Data System (ADS)

UNIAXIAL zero-to-tension load controlled tests at stress rates differing by three orders of magnitude were performed on annealed AISI Type 304 stainless steel. The maximum stress was determined either as the stress reached in displacement control at one per cent strain (History I), or as the stress reached after a 1050 s relaxation test at one per cent strain (History II). The tests of History III were identical to those of History I, except that the specimens were subjected to cyclic hardening prior to the start of the ratchetting test. The ratchet strain accumulations in Histories I and II are significant and depend on stress rate. A stress rate decrease increases the accumulated ratchet strain. The final ratchet strain accumulation is independent of stress rate sequence. In History II, no ratchet strain was found at any stress rate. If the steel had behaved in a rate-independent fashion, no ratchet strain accumulation should have been found in any of the tests. They were performed with an MTS servohydraulic, computer controlled testing machine, a clip on-extensometer and digitized data acquisition.

Ruggles, M. B.; Krempl, E.

224

Selection of Wire Electrical Discharge Machining Process Parameters on Stainless Steel AISI Grade-304 using Design of Experiments Approach  

NASA Astrophysics Data System (ADS)

Wire electrical discharge machining (WEDM) is a specialized thermal machining process capable of accurately machining parts of hard materials with complex shapes. Parts having sharp edges that pose difficulties to be machined by the main stream machining processes can be easily machined by WEDM process. Design of Experiments approach (DOE) has been reported in this work for stainless steel AISI grade-304 which is used in cryogenic vessels, evaporators, hospital surgical equipment, marine equipment, fasteners, nuclear vessels, feed water tubing, valves, refrigeration equipment, etc., is machined by WEDM with brass wire electrode. The DOE method is used to formulate the experimental layout, to analyze the effect of each parameter on the machining characteristics, and to predict the optimal choice for each WEDM parameter such as voltage, pulse ON, pulse OFF and wire feed. It is found that these parameters have a significant influence on machining characteristic such as metal removal rate (MRR), kerf width and surface roughness (SR). The analysis of the DOE reveals that, in general the pulse ON time significantly affects the kerf width and the wire feed rate affects SR, while, the input voltage mainly affects the MRR.

Lingadurai, K.; Nagasivamuni, B.; Muthu Kamatchi, M.; Palavesam, J.

2012-06-01

225

Investigation of corrosion of commercial grade AISI 316L stainless steel liner plates in desalination plant conditions  

SciTech Connect

The corrosion of AISI Type 316L stainless steel (316L SS) liner plates in the flash chambers of a multistage flash (MSF) desalination plant, located on the Arabian Gulf coast was investigated. The 316L SS liner plates developed severe corrosion within six years of operation. This study was conducted to develop an understanding of the mode and causes of corrosion of the liner plates, and to determine the effect of heat treatment (annealing or heat effect during welding) and temperature of salt solution on corrosion of the liner plates. Specimens of the liner plates were studied in as-received (AR) condition and after being heat treated (HT) at 900 C in air and air-cooled to room temperature. Electrochemical techniques were used to measure the corrosion of the specimens. Scanning electron microscope (SEM) installed with energy dispersive (ED) X-ray diffraction capability was used for identification of compositional and structural changes in the specimens during heat treatment and corrosion. The results showed that: (1) Commercial grade 316L SS is susceptible to pitting, crevice and grain boundary corrosion under the operating conditions in the desalination plant. The heat-affected-zone (HAZ) had larger grains and corroded more severely than other parts of the liner plates. (2) The liner plates had randomly distributed inclusions containing Ti, Cr, Mo, Mn, and S in the structure. (3) Measurement of the corrosion rate. (4) Metallographic investigation of the AR and HT samples.

Saricimen, H.; Jarrah, N.R.; Allam, I.M. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Research Inst.

1994-12-31

226

A Local Damage Approach to Predict Crack Initiation in Type AISI 316L(N) Stainless Steel  

NASA Astrophysics Data System (ADS)

A local damage approach based on plastic strain equivalent to uniform strain and grain diameter of the material is proposed for prediction of crack initiation. Plane strain, plane stress, and 3D FEM simulations are carried out for compact tension (CT) geometry with blunt notch of different a/ W ratios under mode-I loading. Elastic-plastic fracture parameters have been estimated based on certain assumptions on blunting at notch tip and micromechanisms of events leading to onset of crack. The various crack initiation parameters evaluated based on proposed local damage approach and initial assumptions have been verified by conducting experiments on CT specimens and subsequent scanning electron microscopy study on fracture surface. The laboratory scale experimental results of AISI 316L(N) stainless steel material are in good agreement with FEM-predicted fracture parameters for notch type of stress raisers. The local damage approach and FEM procedure established in the present study would be easily extendable to the analysis of stress raisers in components for the prediction of crack initiation under elastic-plastic condition.

Krishnan, S. A.; Sasikala, G.; Moitra, A.; Albert, S. K.; Bhaduri, A. K.

2014-05-01

227

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

NASA Astrophysics Data System (ADS)

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.

Kahrobaee, Saeed; Kashefi, Mehrdad

2015-01-01

228

EVALUACIÓN DE LA CORROSIÓN EN CALIENTE POR MÉTODOS ELECTROQUÍMICOS DE UN ACERO AISI 304H EN PRESENCIA DEL ÓXIDO DE NÍQUEL COMO INHIBIDOR. HOT CORROSION EVALUATION BY ELECTROCHEMICAL METHODS OF STAINLESS STEEL AISI 304H IN PRESENCE OF NICKEL OXIDE AS INHIBITOR  

Microsoft Academic Search

In this research, the behaviour of nickel oxide as inhibitor of hot corrosion of stainless steel AISI 304H in presence of a salt compound for 80% V2O5 - 20%Na2SO4 in weight and oxidant atmosphere of 99%O2 - 1%SO2 was studied. Two molars ratios inhibitor \\/ salt 2:1 and 3:1 were used and electrochemical techniques as linear polarization resistance, EIS and

DARIO YESID; HUBER A. ANAYA

2007-01-01

229

[AL amyloidosis].  

PubMed

AL amyloidosis belongs to the group of conformational diseases. It is the most common type of amyloidosis with an estimated 500 new cases per year in France. It is due to a small and usually indolent plasma cell clone which synthesizes an unstable, misfolded monoclonal immunoglobulin light chain that is prone to aggregate and form amyloid fibrils. Non-invasive biopsy such as abdominal fat aspiration or minor salivary gland biopsy should be performed to confirm the diagnosis and if negative, involved tissues have to be examined. Clinical presentation is very diverse, as AL amyloidosis can affect almost any organ or tissue in the body, other than the brain. The kidney is the most frequent organ involved, whereas heart disease characterized by restrictive cardiomyopathy is the most severe. Early diagnosis, before advanced cardiomyopathy, is essential for improving outcome. The association of alkylating agent and high-dose dexamethasone is effective in almost two-thirds of patients. Combinations of proteasome inhibitors, dexamethasone, and alkylating agents achieve high response rates. Close monitoring of clonal and organ response is mandatory to guide therapy changes and duration. New treatments designed to eliminate amyloid deposits are under development. PMID:25194219

Jaccard, A; Desport, E; Mohty, D; Bridoux, F

2015-02-01

230

Corrosion-Erosion Effect on TiN/TiAlN Multilayers  

NASA Astrophysics Data System (ADS)

The goal of this work is to study electrochemical behavior under corrosion-erosion conditions for [TiN/TiAlN] n multilayer coatings with bilayer number ( n) of 2, 6, 12, and 24 and/or bilayer period (?) of 1500, 500, 250, 150, and 125 nm deposited by a magnetron sputtering technique on Si (100) and AISI 1045 steel substrates. The Ti-N and Ti-Al-N structures for multilayer coatings were evaluated via x-ray diffraction analysis. Silica particles were used as the abrasive material in corrosion-erosion tests within the 0.5 M H2SO4 solution at impact angles of 30° and 90° over the surface. The electrochemical characterization was carried out using the polarization resistance technique (Tafel) to observe changes in corrosion rates as a function of the bilayer number ( n) or bilayer period (?) and impact angle. Corrosion rate values of 359 mpy of uncoated steel substrate and 103 mpy for substrate coated with n = 24 (? = 125 nm) under an impact angle of 30° were found. On the other hand, with an impact angle of 90° the corrosion rate exhibited 646 mpy on uncoated steel substrate and 210 mpy for substrate coated with n = 24 (? = 125 nm). This behavior was related to the curves of mass loss for both coated samples and the surface damage was analyzed via SEM images for the two different impact angles. These results indicate that TiN/TiAlN multilayer coatings deposited on AISI 1045 steel are a practical solution for applications in erosive-corrosive environments.

Caicedo, J. C.; Cabrera, G.; Aperador, W.; Escobar, C.; Amaya, C.

2012-09-01

231

Effects of surface mechanical attrition treatment (SMAT) on a rough surface of AISI 316L stainless steel  

NASA Astrophysics Data System (ADS)

Surface mechanical attrition treatment (SMAT) improves mechanical properties of metallic materials through the formation of nanocrystallites at their surface layer. It also modifies the morphology and roughness of the work surface. Surface roughening by the SMAT has been reported previously in a smooth specimen, however in this study the starting point was a rough surface and a smoothening phenomenon is observed. In this paper, the mechanisms involved in the surface smoothening of AISI 316L stainless steel during the SMAT are elucidated. The SMAT was conducted on a specimen with a roughness of Ra = 3.98 ?m for 0-20 min. The size of milling balls used in the SMAT was varied from 3.18 mm to 6.35 mm. The modification of subsurface microhardness, surface morphology, roughness and mass reduction of the specimen due to the SMAT were studied. The result shows the increasing microhardness of the surface and subsurface of the steel due to the SMAT. The impacts of milling balls deform the surface and produce a flat-like structure at this layer. Surface roughness decreases until its saturation is achieved in the SMAT. The mass reduction of the specimens is also detected and may indicate material removal or surface erosion by the SMAT. The size of milling ball is found to be the important feature determining the pattern of roughness evolution and material removal during the SMAT. From this study, two principal mechanisms in the evolution of surface morphology and roughness during the SMAT are proposed, i.e. indentation and surface erosion by the multiple impacts of milling balls. A comparative study with the results of the previous experiment indicates that the initial surface roughness has no influence in the work hardening by the SMAT but it does slightly on the saturated roughness value obtained by this treatment.

Arifvianto, B.; Suyitno; Mahardika, M.

2012-03-01

232

AISI/DOE Technology Roadmap Program: A Technology of Low Coal Rate and High Productivity of RHF Ironmaking  

SciTech Connect

An economical and environment-friendly ironmaking process based on heating the chemiexecy self-sufficient green balls of iron ore and coal in a hearth furnace is being developed with financial support from AISI members and DOE. DRI, which is hot (1400 C), dense (3.2 g/cm) and of high degree of metallization (95%), has been produced in laboratory and in a pilot plant in Genoa, Italy. Products of such quality have been made from American and Brazilian ores, BOF sludge, EAF dust/BOF sludge mixtures and millscale. The removal of zinc and lead from green balls by this process is essentially complete. In comparison with typical blast furnace operation, the new technology with a melter would have a lower total coal rate by 200kg.THM. The elimination of cokemaking and high temperature agglomeration steps, and a simpler gas handling system would lead to lower capital and operating costs. In comparison with commercial RHF practice it is different in atmosphere (fully oxidized at 1600 to 1650 C), in bed height (120 mm instead of 20-25 mm) and in pellet composition (much less coal but of higher VM). The combined effect leads to three times higher furnace productivity, lower coal consumption and superior DRI quality. The risk of re-oxidation (slag formation) and dusty operation are practiexecy eliminated. The process is stable, tolerant and independent of the size, shape and movement of the hearth. However, materials handling (e.g., discharge of hot DRI) and the exact energy savings have to be established in a larger furnace, straight or rotary, and in a continuous mode of operation.

Wei-Kao Lu

2002-09-15

233

Improvement of Electrochemical Surface Properties in Steel Substrates Using a Nanostructured CrN/AlN Multilayer Coating  

NASA Astrophysics Data System (ADS)

Improvement of corrosion properties on AISI D3 steel surfaces coated with [CrN/AlN] n multilayered system deposited for various periods (?) via magnetron sputtering has been studied in this work exhaustively. For practical effects compared were the latter properties with CrN and AlN single layers deposited with the same conditions as the multilayered systems. The coatings were characterized in terms of crystal phase; chemical composition, micro-structural, and electrochemical properties by x-ray diffractometry, energy dispersive x-ray, Fourier transforming infrared spectroscopy, atomic force microscopy, scanning electron microscopy, Tafel polarization curves, and electrochemical impedance spectroscopy. Corrosion evolution was observed via optical microscopy. Results from x-ray diffractometry analysis revealed that the crystal structure of [CrN/AlN] n multilayered coatings has an NaCl-type lattice structure and hexagonal structure (wurtzite-type) for CrN and AlN, respectively, i.e., it was made non-isostructural multilayered. The best behavior was obtained by the multilayered period: ? = 60 nm (50 bilayers), showing the maximum corrosion resistance (polarization resistance of 1.18 K?, and corrosion rate of 1.02 mpy). Those results indicated an improvement of anticorrosive properties, compared to the CrN/AlN multilayer system with 1 bilayer at 98 and 80%, respectively. Furthermore, the corrosion resistance of steel AISI D3 is improved beyond 90%. These improvement effects in multilayered coatings could be attributed to the number of interfaces that act as obstacles for the inward and outward diffusions of ion species, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface. Moreover, the interface systems affect the means free path on the ions toward the metallic substrate, due to the decreasing of the defects presented in the multilayered coatings.

Cabrera, G.; Torres, F.; Caicedo, J. C.; Aperador, W.; Amaya, C.; Prieto, P.

2012-01-01

234

Ion Beam Analysis, structure and corrosion studies of nc-TiN/a-Si3N4 nanocomposite coatings deposited by sputtering on AISI 316L  

NASA Astrophysics Data System (ADS)

In this work, nanocomposite coatings of nc-TiN/a-Si3N4, were deposited on AISI 316L stainless steel substrate by a DC and RF reactive magnetron co-sputtering technique using an A-N2 plasma. The structure of the coatings was characterized by means of XRD (X-ray Diffraction). The substrate and coating corrosion resistance were evaluated by potentiodynamic polarization using a Ringer solution as electrolyte. Corrosion tests were conducted with the purpose to evaluate the potential of this coating to be used on biomedical alloys. IBA (Ion Beam Analysis) techniques were applied to measure the elemental composition profiles of the films and, XPS (X-ray Photoelectron Spectroscopy) were used as a complementary technique to obtain information about the compounds present in the films. The nanocomposite coatings of nc-TiN/a-Si3N4 show crystalline (TiN) and amorphous (Si3N4) phases which confer a better protection against the corrosion effects compared with that of the AISI 316L.

García, J.; Canto, C. E.; Flores, M.; Andrade, E.; Rodríguez, E.; Jiménez, O.; Solis, C.; de Lucio, O. G.; Rocha, M. F.

2014-07-01

235

Microstructural Characterization and Properties Evaluation of Ni-Based Hardfaced Coating on AISI 304 Stainless Steel by High Velocity Oxyfuel Coating Technique  

NASA Astrophysics Data System (ADS)

The present study concerns a detailed investigation of microstructural evolution of nickel based hardfaced coating on AISI 304 stainless steel by high velocity oxy-fuel (HVOF) deposition technique. The work has also been extended to study the effect of coating on microhardness, wear resistance and corrosion resistance of the surface. Deposition has been conducted on sand blasted AISI 304 stainless steel by HVOF spraying technique using nickel (Ni)-based alloy [Ni: 68.4 wt pct, chromium (Cr): 17 wt pct, boron (B): 3.9 wt pct, silicon (Si): 4.9 wt pct and iron (Fe): 5.8 wt pct] of particle size 45 to 60 ?m as precursor powder. Under the optimum process parameters, deposition leads to development of nano-borides (of chromium, Cr2B and nickel, Ni3B) dispersion in metastable and partly amorphous gamma nickel (?-Ni) matrix. The microhardness of the coating was significantly enhanced to 935 VHN as compared to 215 VHN of as-received substrate due to dispersion of nano-borides in grain refined and partly amorphous nickel matrix. Wear resistance property under fretting wear condition against WC indenter was improved in as-deposited layer (wear rate of 4.65 × 10-7 mm3/mm) as compared to as-received substrate (wear rate of 20.81 × 10-7 mm3/mm). The corrosion resistance property in a 3.56 wt pct NaCl solution was also improved.

Sharma, Prashant; Majumdar, Jyotsna Dutta

2013-01-01

236

CNC TORNA TEZGAHINDA AISI 304 ÇEL?KLER?N ??LENEMES?NDE OPT?MUM YÜZEY PÜRÜZLÜLÜ?ÜNÜ SA?LAYACAK KESME PARAMETRELER?N?N TESP?T?  

Microsoft Academic Search

The purpose of this study, is to determine optimum machinability parametres required to obtain ideal surface roughness for AISI 304 austenitic stainless steel processed on the CNC lathe. Changes made in the composition of stainless steels so as to provide the mechanical and chemical properties desired according to the fields of application affect also their machining. Surface quality changes according

Özgür TEKASLAN; Nedim GERGER; Kara Harp Okulu

237

High temperature oxidation of HFPD thermal-sprayed MCrAlY coatings in simulated gas turbine environments  

NASA Astrophysics Data System (ADS)

NiCrAlY and CoNiCrAlY powders were thermal-sprayed using the high frequency pulse detonation method (HFPD) onto AISI 310 austenitic stainless steel samples to obtain dense, adherent, high temperature oxidation resistant coatings. The oxidation behavior of both types of coatings in a 1000°C simulated gas turbine environment was experimentally determined. The porosity, hardness, coating thickness, and microstructure were not significantly modified by the high temperature oxidation cycles, but the internal oxidation increases significantly after a very low oxidation time. Surface phase composition was evaluated using x-ray diffraction (XRD) and scanning electron microscope (SEM) techniques, revealing the formation of a continuous and highly protective alumina layer. The oxidation kinetics of both coatings can be characterized by parabolic rate constants, which are very close to those for the formation of aluminum oxide on nickel or cobalt based alloys at similar conditions.

Belzunce, F. J.; Higuera, V.; Poveda, S.; Carriles, A.

2002-12-01

238

Wear and Corrosion Behavior of CoNiCrAlY Bond Coats  

NASA Astrophysics Data System (ADS)

The present study focusses on the wear and microstructural properties of CoNiCrAlY coatings fabricated on AISI 316L stainless steel substrate by using the (HVOF) and (CGDS) methods. A triobiological test was performed on the samples in order to understand the wear behaviour of thermally sprayed coatings. The microstructures of as-sprayed and worn out coatings were investigated by scanning electron microscopy. Coating hardness measurements were performed with nanoindentation. HVOF coating revealed lower hardness value in comparison with CGDS. Studies depicted better wear resistance of the CGDS sprayed with He, when compared to CGDS N2 and HVOF processing. Potentiodynamic polarization curves and tafel extrapolation experiments were carried at 7.5 pH value using 3.5 % NaCl as an electrolyte. Electrochemical studies depicted better corrosion resistance of the He processed coating when compared to N2 and HVOF processing.

Rathod, W. S.; Khanna, A. S.; Rathod, R. C.; Sapate, S. G.

2014-07-01

239

Microstructure and corrosion resistance of nanocrystalline TiZrN films on AISI 304 stainless steel substrate  

SciTech Connect

This study investigated the microstructure and properties of nanocrystalline TiZrN films on AISI 304 stainless steel substrate. TiZrN films were prepared by reactive magnetron sputtering based on the previous optimum coating conditions (substrate temperature, system pressure, nitrogen flow, etc.) for TiN and ZrN thin films. The composition ratio of TiZrN coatings were adjusted by changing the Zr target power, while keeping the Ti target power constant. Experiments were conduced to find the optimum composition with desired properties. The ratio of TiZrN composition was analyzed by x-ray photoelectron spectroscopy and Rutherford backscattering spectrometer. In terms of phase formation, there were two types of coatings that were considered: single-phase solid solutions of TiZrN and interlacing nuclei of TiZr in the matrix of TiZrN. The thickness of all TiZrN films as measured by the secondary ion mass spectroscopy was about 500 nm, and the composition depth profiles indicated that the compositions in the TiZrN films were uniform from the film surface to the 304 stainless steel substrate. The crystal structure of the TiZrN films was determined by x-ray diffraction using a M18XHF-SRA diffractometer with Cu K{sub {alpha}} radiation. A diffraction peak of TiZrN (002) was observed between that of TiN (002) and ZrN (002); similarly, a diffraction peak of TiZrN (111) was observed between that of TiN(111) and ZrN(111), respectively. The corrosion resistance of the TiZrN film deposited on the 304 stainless steel has been investigated by electrochemical measurement. The electrolyte, 0.5M H{sub 2}SO{sub 4} containing 0.05M KSCN, was used for the potentiodynamic polarization. The potentiodynamic scan was conducted from -800 to 800 mV standard calomel electrode (SCE).

Lin, Yu-Wei; Huang, Jia-Hong; Yu, Ge-Ping [Instrument Technology Research Center, 20 R and D Road VI, Hsinchu Science-Based Industrial Park, Hsinchu 300, Taiwan, Republic of China and Department of Engineering and System Science, National Tsing Hua University, 101 Kuang Fu Rd., Sec. 2, Hsinchu 300, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, 101 Kuang Fu Rd., Sec. 2, Hsinchu 300, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, 101 Kuang Fu Rd., Sec. 2, Hsinchu 300, Taiwan, Republic of China and Institute of Nuclear Engineering and Science, National Tsing Hua University, 101 Kuang Fu Rd., Sec. 2, Hsinchu 300, Taiwan (China)

2010-07-15

240

Thermal conductivity of PVD TiAlN films using pulsed photothermal reflectance technique  

NASA Astrophysics Data System (ADS)

In the present work, we have measured thermal-conductivity of industrial thin film TiAlN with a thickness of around 3 ?m. These films are used in machining industry for cutting tools in order to increase their service life. A series of TiAlN coating with a different Al/Ti atomic ratio were deposited on Fe-304 stainless steel (AISI304) substrate by a lateral rotating cathode arc process. The samples were then coated with a 0.8 ?m gold layer on top by magnetron sputtering. We present the thermal-conductivity measurement of these samples using pulsed photothermal reflectance (PPR) technique at room temperature. The thermal conductivity of the pure TiN coating is about 11.9 W/mK. A significant decrease in thermal conductivity was found with increasing Al/Ti atomic ratio. A minimum thermal conductivity of about 4.63 W/mK was obtained at the Al/Ti atomic ratio of around 0.72.

Ding, Xing-Zhao; Samani, M. K.; Chen, George

2010-11-01

241

Improvement of localised corrosion resistance of AISI 2205 Duplex Stainless Steel joints made by gas metal arc welding under electromagnetic interaction of low intensity  

NASA Astrophysics Data System (ADS)

The resistance to localised corrosion of AISI 2205 duplex stainless steel plates joined by Gas Metal Arc Welding (GMAW) under the effect of electromagnetic interaction of low intensity (EMILI) was evaluated with sensitive electrochemical methods. Welds were made using two shielding gas mixtures: 98% Ar + 2% O2 (M1) and 97% Ar + 3% N2 (M2). Plates were welded under EMILI using the M1 gas with constant welding parameters. The modified microstructural evolution in the high temperature heat affected zone and at the fusion zone induced by application of EMILI during welding is associated with the increase of resistance to localised corrosion of the welded joints. Joints made by GMAW using the shielding gas M2 without the application of magnetic field presented high resistance to general corrosion but high susceptibility to undergo localised attack.

García-Rentería, M. A.; López-Morelos, V. H.; García-Hernández, R.; Dzib-Pérez, L.; García-Ochoa, E. M.; González-Sánchez, J.

2014-12-01

242

Mechanical and tribological properties of AISI 304 stainless steel nitrided by glow discharge compared to ion implantation and plasma immersion ion implantation  

NASA Astrophysics Data System (ADS)

Results about mechanical and tribological behavior of AISI 304 stainless steel nitrided by three different ion beam processes - glow discharge (GD), ion implantation (II) and plasma immersion ion implantation (PI3) are reported. Expanded austenite ? N and nitrides phases (Fe 2+ xN, ?'-Fe 4N and Cr-N) were identified as a function of nitriding conditions. Hardness (H) and elastic modulus (E) profiles were obtained by instrumented penetration. The hardness reached values as high as 21 GPa by PI3. Tribological behavior was studied by reciprocating sliding tests with a WC (Co) ball at room temperature (RT) in dry condition. Different wear regimes were identified in the friction coefficient profiles. The profile form and the running-in distance are strongly dependent on the nitriding process. Adhesive and abrasive wear components can be inferred from these friction profiles. Hardness and tribological performance, after the nitriding processes, are discussed in terms of surface microstructure.

Foerster, C. E.; Serbena, F. C.; da Silva, S. L. R.; Lepienski, C. M.; Siqueira, C. J. de M.; Ueda, M.

2007-04-01

243

Cyclic response-electrochemical interaction in mono- and polycrystalline AISI 316L stainless steel in H[sub 2]SO[sub 4] solution-III. Potential dependence of the mechanical behavior during corrosion fatigue  

Microsoft Academic Search

Measurements of mechanical parameters and surface examinations have been carried out on mono- and polycrystalline specimens of an AISI 316L stainless steel which were cycled in a 1N H[sub 2]SO[sub 4] solution. Analysis was made in relation to both the number of cycles and the applied potentials. The environment was found to have no influence on such bulk properties as

Y. F. Li; G. C. Farrington; C. Laird

1993-01-01

244

Schwartz et al., Tella et al., Foltin et al., Trippenbach et al., Regalado et al., Magnano et al., Levin et al., Hale et al., Cocaine day  

E-print Network

., Levin et al., Hale et al., Cocaine day 7 day dry-out period Session I: Baseline Session II: Fixed 8mg, and 32 mg\\70kg respectively with a 100kg cap. All cocaine self-administration sessions take place at the Yale Center for Clinical Investigations Hospital Research Unit. Detecting Signatures of Cocaine Using

Massachusetts at Amherst, University of

245

Long-term evaluation of solid oxide fuel cell candidate materials in a 3-cell generic stack test fixture, part III: Stability and microstructure of Ce-(Mn,Co)-spinel coating, AISI441 interconnect, alumina coating, cathode and anode  

NASA Astrophysics Data System (ADS)

A generic solid oxide fuel cell stack test fixture was developed to evaluate candidate materials and processing under realistic conditions. Part III of the work investigated the stability of Ce-(Mn,Co) spinel coating, AISI441 metallic interconnect, alumina coating, and cell's degradation. After 6000 h test, the spinel coating showed densification with some diffusion of Cr. At the metal interface, segregation of Si and Ti was observed, however, no continuous layer formed. The alumina coating for perimeter sealing areas appeared more dense and thick at the air side than the fuel side. Both the spinel and alumina coatings remained bonded. EDS analysis of Cr within the metal showed small decrease in concentration near the coating interface and would expect to cause no issue of Cr depletion. Inter-diffusion of Ni, Fe, and Cr between spot-welded Ni wire and AISI441 interconnect was observed and Cr-oxide scale formed along the circumference of the weld. The microstructure of the anode and cathode was discussed relating to degradation of the top and middle cells. Overall, the Ce-(Mn,Co) spinel coating, alumina coating, and AISI441 steel showed the desired long-term stability and the developed generic stack fixture proved to be a useful tool to validate candidate materials for SOFC.

Chou, Yeong-Shyung; Stevenson, Jeffry W.; Choi, Jung-Pyung

2014-07-01

246

Microstructures and Mechanical Performance of Plasma-Nitrided Al0.3CrFe1.5MnNi0.5 High-Entropy Alloys  

NASA Astrophysics Data System (ADS)

This study investigates the effect of plasma nitriding at 798 K (525 °C) on microstructures and the mechanical performance of Al0.3CrFe1.5MnNi0.5 high-entropy alloys (HEAs) obtained using different cast and wrought processing. All the alloys can be well nitride, with a thickness of around 80 ?m, and attain a peak hardness level around Hv 1300 near the surface. The main nitride phases are CrN, AlN, and (Mn, Fe)4N. Those of the substrates are bcc, fcc, Al-, and Ni-rich B2 precipitates, and ? phase. Their relative amounts depend on the prior processing and also change under the heat treatment during nitriding. The formation of ? phase during nitriding could in-situ harden the substrate to attain the suitable level required for wear applications. This gives the advantage in simplifying the processing for making a wear-resistance component or a mold since austenitizing, quench hardening, and tempering required for steels such as SACM and SKD steels are no longer required and final finishing can be accomplished before nitriding. Nitrided Al0.3CrFe1.5MnNi0.5 samples have much better wear resistance than un-nitrided ones by 49 to 80 times and also exhibit superior adhesive wear resistance to conventional nitrided alloys: nitriding steel SACM-645 (AISI 7140), 316 stainless steel, and hot-mold steel SKD-61 (AISI H13) by 22 to 55 times depending on prior processing. The superiority is due to the fact that the present nitrided alloys possess a much thicker highly hardened layer than the conventional alloys.

Tang, Wei-Yeh; Chuang, Ming-Hao; Lin, Su-Jien; Yeh, Jien-Wei

2012-07-01

247

Primary AL Amyloidosis  

MedlinePLUS

... be administered in combination with other treatments. REVLIMID (lenalidomide) (CC-5013) is a immunomodulatory drug; a derivative ... AL amyloidosis. Findings from initial trials indicate that lenalidomide can be effective in treating AL amyloidosis. There ...

248

About ALS: FAQ  

MedlinePLUS

... disease deterioration in these mice. Clinical trials are of the utmost importance to investigate if the effects seen in the mouse model are seen in humans with ALS. Another question is whether this exciting result found in a model of familial ALS is applicable to sporadic ALS that ...

249

Hardness properties and high-temperature wear behavior of nitrided AISI D2 tool steel, prior and after PAPVD coating  

Microsoft Academic Search

Wear experiments in the range of 25–600°C have been conducted on samples of D2 tool steel in different conditions involving unnitrided, nitrided and nitrided and coated with Balinit® A (TiN) and Balinit® Futura (TiAlN) deposited industrially at Balzers (Amherst, NY, USA), by means of PAPVD. The results indicate that coating the nitrided D2 tool steel substrate with these two films

M. H. Staia; Y. Pérez-Delgado; C. Sanchez; A. Castro; E. Le Bourhis; E. S. Puchi-Cabrera

2009-01-01

250

Influence of Surface Position along the Working Range of Conoscopic Holography Sensors on Dimensional Verification of AISI 316 Wire EDM Machined Surfaces  

PubMed Central

Conoscopic holography (CH) is a non-contact interferometric technique used for surface digitization which presents several advantages over other optical techniques such as laser triangulation. Among others, the ability for the reconstruction of high-sloped surfaces stands out, and so does its lower dependence on surface optical properties. Nevertheless, similarly to other optical systems, adjustment of CH sensors requires an adequate selection of configuration parameters for ensuring a high quality surface digitizing. This should be done on a surface located as close as possible to the stand-off distance by tuning frequency (F) and power (P) until the quality indicators Signal-to-Noise Ratio (SNR) and signal envelope (Total) meet proper values. However, not all the points of an actual surface are located at the stand-off distance, but they could be located throughout the whole working range (WR). Thus, the quality of a digitized surface may not be uniform. The present work analyses how the quality of a reconstructed surface is affected by its relative position within the WR under different combinations of the parameters F and P. Experiments have been conducted on AISI 316 wire EDM machined flat surfaces. The number of high-quality points digitized as well as distance measurements between different surfaces throughout the WR allowed for comparing the metrological behaviour of the CH sensor with respect to a touch probe (TP) on a CMM. PMID:24662452

Fernández, Pedro; Blanco, David; Rico, Carlos; Valiño, Gonzalo; Mateos, Sabino

2014-01-01

251

Corrosion behaviour of sensitized AISI-type 316L stainless steel in molten carbonate fuel cell in cathode-gas environment  

NASA Astrophysics Data System (ADS)

Corrosion of the cell components is a major problem in the development of the molten carbonate fuel cell (MCFC). This study describes the effect of sensitization on the corrosion characteristics of AISI-type 316L stainless steel in a 62/38 lithium-potassium carbonate eutectic melt in the cathode-gas environment. After solution treatment at 1200°C for 4 h followed by sensitization treatment at 650°C for predetermined time, the corrosion behaviour of the sensitized sample is analyzed electrochemically by a potentiodynamic method. The sensitized sample displays behaviour which is typical of active-passive transition. Increasing the time of the sensitization treatment causes the corrosion potential to shift in the cathodic direction. In addition, the passive film becomes more unstable and supports a high passive current, i.e., the substrate is more susceptible to intergranular corrosion (IGC). Morphological observation of samples immersed in a carbonate melt reveal a change in corrosion mechanism from initial IGC to localized corrosion. Huge cavities develop from grooves after 200 h of immersion in a carbonate melt. A combination of a Cr-depleted region due to sensitization and decreasing oxygen concentration from top to bottom of the oxide layer, is considered to be the main reason for the change in corrosion morphology.

Lee, Kab Soo; Cho, Kyehyun; Lim, Tae Hoon; Hong, Seong-Ahn; Kim, Hwayong

252

Effect of pulse laser parameters on TiC reinforced AISI 304 stainless steel composite coating by laser surface engineering process  

NASA Astrophysics Data System (ADS)

In this work, TiC reinforced steel composite layer has been produced by laser scanning over the preplaced TiC powder on AISI 304 steel substrate, using a pulse Nd:YAG laser. Depending on the pulse laser parameters, TiC either deposited or dispersed on the surface of steel substrate. Depth and width of laser processed TiC-steel composite layer has been deliberated from the SEM images at the transverse cross section of the laser scanned samples. Hardness of the laser processed composite layer has been measured through Vickers micro-hardness tester. Effect of pulsed laser parameters i.e. peak power, pulse duration, overlapping factor (corresponding to scan speed and frequency) on micro-hardness, composite layer profile (depth and width) and microstructure of the laser processed TiC-steel composite layer has been studied. From the experimental analysis, it is revealed that, laser peak power and overlapping factor have significant effect on the TiC-steel composite layer profile and its hardness value.

Sahoo, Chinmaya Kumar; Masanta, Manoj

2015-04-01

253

The Microstructures and Wear Resistance of Gas-Nitrided and Ionically Nitrided AISI H10 Dies with Narrow Gaps Designed for the Hot Extrusion of Aluminium  

NASA Astrophysics Data System (ADS)

Dies made from AISI H10 die steel with narrow and deep gaps were nitrided by various manufacturers of equipment for ionic and gas nitriding. The manufacturers chose the optimum nitriding parameters themselves, based on their experience with extrusion dies. The resulting microstructures showed differences in terms of the presence or absence of a compound layer, the thickness of the layer and its ?/?? phase ratio (XRD), the nitriding depth and the microhardness values. The obtained nitriding depths, the maximum microhardness of the nitrided surfaces and the ? /?? phase ratio were usually similar for dies from the same manufacturer, while the dies from different manufacturers tended to have different values. Samples with various nitrided microstructures were laboratory tested for wear resistance with a newly designed test rig that provided a simulation of the tribological conditions for the hot extrusion of aluminium. The results of the study indicate that dies with a greater nitriding depth in combination with a compound layer composed primarily of just one phase (in our case the ? phase) exhibited better wear resistance than those dies with a small nitriding depth and with an equal share of the two phases.

Tercelj, Milan; Smolej, Anton; Vecko-Pirtovsek, Tatjana; Turk, Rado

254

Studies on the influence of metallurgical variables on the stress corrosion behavior of AISI 304 stainless steel in sodium chloride solution using the fracture mechanics approach  

SciTech Connect

Stress corrosion data on a nuclear grade AISI type 304 stainless steel in a boiling solution of 5M NaCl + 0.15M Na{sub 2}SO{sub 4} + 3 mL/L HCl (bp 381 K) for various metallurgical conditions of the steel are presented in this article. The metallurgical conditions used are solution annealing, sensitization, 10 pct cold work, 20 pct cold work, solution annealing + sensitization, 10 pct cold work + sensitization, and 20 pct cold work + sensitization. The fracture mechanics approach has been used to obtain quantitative data on the stress corrosion crack growth rates. The stress intensity factor, K{sub I}, and J integral, J{sub I}, have been used as evaluation parameters. The crack growth rates have been measured using compact tension type samples under both increasing and decreasing stress intensity factors. A crack growth rate of 5 {times} 10{sup {minus}11} m/s was chosen for the determination of threshold parameters. Results of the optical microscopic and fractographic examinations are presented. Acoustic signals were recorded during crack growth. Data generated from acoustic emissions, activation energy measurements, and fractographic features indicate hydrogen embrittlement as the possible mechanism of cracking.

Khatak, H.S.; Gnanamoorthy, J.B.; Rodriguez, P. [Indira Gandhi Centre for Atomic Research, Tamil Nadu (India)

1996-05-01

255

The Effect of Surface Roughness on the Corrosion Properties of Type AISI 304 Stainless Steel in Diluted NaCl and Urban Rain Solution  

NASA Astrophysics Data System (ADS)

Due to their good corrosion resistance, favorable mechanical properties, and reasonable price regarding their excellent properties, austenitic stainless steels have, over recent decades, become one of the alloys that are increasingly used in civil engineering and building, as well as for specific architectural purposes. Architects often design stainless steel exterior elements with higher surface roughnesses, which are not resistant to corrosion processes. The aim of this work was to investigate the influence of different types of surface finishes to stainless steel of quality AISI 304 on the corrosion properties of this steel. In order to achieve this goal, electrochemical tests were performed on different surface finishes in two different environments: in an NaCl aqueous solution, and in simulated urban rain which contained no chlorides. In addition to the electrochemical methods used, surface roughness was also measured, and XPS surface analyses were performed. The results of the investigation showed that surface roughness affects the growth of the passive layer in urban rain significantly; however, the growth of such a film is retarded in the case of the NaCl aqueous solution. Based on the results of the performed analyses, it was found that, in the NaCl solution, the pitting potential depended strongly upon the surface roughness and the surface finish, but this was not true for the samples tested in urban rain.

Leban, Mirjam Bajt; Mikyška, ?rt; Kosec, Tadeja; Markoli, Boštjan; Kova?, Janez

2014-05-01

256

Finite Element Modelling of the effect of tool rake angle on tool temperature and cutting force during high speed machining of AISI 4340 steel  

NASA Astrophysics Data System (ADS)

In this paper, a Finite Element Method (FEM) based on the ABAQUS explicit software which involves Johnson-Cook material model was used to simulate cutting force and tool temperature during high speed machining (HSM) of AISI 4340 steel. In this simulation work, a tool rake angle ranging from 0° to 20° and a range of cutting speeds between 300 to 550 m/min was investigated. The purpose of this simulation analysis was to find optimum tool rake angle where cutting force is smallest as well as tool temperature is lowest during high speed machining. It was found that cutting forces to have a decreasing trend as rake angle increased to positive direction. The optimum rake angle observed between 10° and 18° due to decrease of cutting force as 20% for all simulated cutting speeds. In addition, increasing cutting tool rake angle over its optimum value had negative influence on tool's performance and led to an increase in cutting temperature. The results give a better understanding and recognition of the cutting tool design for high speed machining processes.

Sulaiman, S.; Roshan, A.; Ariffin, M. K. A.

2013-12-01

257

Experimental Evaluation and Optimization of Flank Wear During Turning of AISI 4340 Steel with Coated Carbide Inserts Using Different Cutting Fluids  

NASA Astrophysics Data System (ADS)

The understanding of cutting fluids performance in turning process is very important in order to improve the efficiency of the process. This efficiency can be determined based on certain process parameters such as flank wear, cutting forces developed, temperature developed at the tool chip interface, surface roughness on the work piece, etc. In this study, the objective is to determine the influence of cutting fluids on flank wear during turning of AISI 4340 with coated carbide inserts. The performances of three types of cutting fluids were compared using Taguchi experimental method. The results show that palm kernel oil based cutting fluids performed better than the other two cutting fluids in reducing flank wear. Mathematical models for cutting parameters such as cutting speed, feed rate, depth of cut and cutting fluids were obtained from regression analysis using MINITAB 14 software to predict flank wear. Experiments were conducted based on the optimized values to validate the regression equations for flank wear and 5.82 % error was obtained. The optimal cutting parameters for the flank wear using S/N ratio were 160 m/min of cutting speed (level 1), 0.18 mm/rev of feed (level 1), 1.75 mm of depth of cut (level 2) and 2.97 mm2/s palm kernel oil based cutting fluid (level 3). ANOVA shows cutting speed of 85.36 %; and feed rate 4.81 %) as significant factors.

Lawal, S. A.; Choudhury, I. A.; Nukman, Y.

2015-01-01

258

Thermally Nitrided Stainless Steels for Polymer Electrolyte Membrane Fuel Cell Bipolar Plates: Part 2: Beneficial Modification of Passive Layer on AISI446  

SciTech Connect

Thermal nitridation of AISI446 mod-1 superferritic stainless steel for 24 h at 1100 C resulted in an adherent, inward growing surface layer based on (Cr, Fe){sub 2}N{sub 1-x} (x = 0--0.5). The layer was not continuous, and although it resulted in low interfacial contact resistance (ICR) and good corrosion resistance under simulated polymer electrolyte membrane fuel cell (PEMFC) cathodic conditions; poor corrosion resistance was observed under simulated anodic conditions. Nitridation for 2 h at 1100 C resulted in little nitrogen uptake and a tinted surface. Analysis by SEM, XPS, and AES suggested a complex heterogeneous modification of the native passive oxide film by nitrogen rather than the desired microns-thick exclusive Cr-rich nitride layer. Surprisingly, this modification resulted in both good corrosion resistance under simulated cathodic and anodic conditions and low ICR, well over an order of magnitude lower than the untreated alloy. Further, little increase in ICR was observed under passivating polarization conditions. The potential of this phenomenon for PEMFC bipolar plates is discussed.

Wang, Heli [National Renewable Energy Laboratory (NREL); Brady, Michael P [ORNL; More, Karren Leslie [ORNL; Meyer III, Harry M [ORNL; Turner, John [National Renewable Energy Laboratory (NREL)

2004-01-01

259

Influence of surface position along the working range of conoscopic holography sensors on dimensional verification of AISI 316 wire EDM machined surfaces.  

PubMed

Conoscopic holography (CH) is a non-contact interferometric technique used for surface digitization which presents several advantages over other optical techniques such as laser triangulation. Among others, the ability for the reconstruction of high-sloped surfaces stands out, and so does its lower dependence on surface optical properties. Nevertheless, similarly to other optical systems, adjustment of CH sensors requires an adequate selection of configuration parameters for ensuring a high quality surface digitizing. This should be done on a surface located as close as possible to the stand-off distance by tuning frequency (F) and power (P) until the quality indicators Signal-to-Noise Ratio (SNR) and signal envelope (Total) meet proper values. However, not all the points of an actual surface are located at the stand-off distance, but they could be located throughout the whole working range (WR). Thus, the quality of a digitized surface may not be uniform. The present work analyses how the quality of a reconstructed surface is affected by its relative position within the WR under different combinations of the parameters F and P. Experiments have been conducted on AISI 316 wire EDM machined flat surfaces. The number of high-quality points digitized as well as distance measurements between different surfaces throughout the WR allowed for comparing the metrological behaviour of the CH sensor with respect to a touch probe (TP) on a CMM. PMID:24662452

Fernández, Pedro; Blanco, David; Rico, Carlos; Valiño, Gonzalo; Mateos, Sabino

2014-01-01

260

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)

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.

Kianersi, Danial; Mostafaei, Amir; Mohammadi, Javad

2014-09-01

261

Al Dimer Dynamics on Al(111)  

NASA Astrophysics Data System (ADS)

Al dimer dynamics on Al(111) at equilibrium and under compression is studied using first-principles density-functional theory calculations. A smooth potential energy surface provides a long-range attraction between the dimer atoms and leads to a substantial temperature window in which dissociation is frozen and exotic dimer dynamics is observed. Surface relaxations play a prominent role in the uncovering of an unexpected ground state and a new diffusion path. A way of affecting growth by compression is illustrated. The possibility of a metal quantum rotor is addressed and further examined using effective-medium theory calculations.

Bogicevic, Alexander; Hyldgaard, Per; Wahnström, Göran; Lundqvist, Bengt I.

1998-07-01

262

Bodybuilding als Sinnsystem  

Microsoft Academic Search

\\u000a Bodybuilder sind körperlich stigmatisierte Normabweichler. Sie werden nicht nur als unintelligent, sondern auch gern als exhibitionistisch,\\u000a narzisstisch, monströs, ekelhaft, abscheulich, widerwärtig, abstoßend – und was der emphatischen Belegungen mehr sind – betrachtet.\\u000a Sie gelten als aufgeblasene, angeberische, eitle „Popanze“, die mit ihren Muskeln „überhaupt nichts“ anzufangen wüssten, denen\\u000a bei jeder Dauerbelastung die Luft wegbleibe und die zu allem Überfluss (wegen

Anne Honer

263

Beamte, die sich als \\  

Microsoft Academic Search

7 Sicherheitspolitik ist also keineswegs wertneutral. Dies betrifft sowohl das Ziel dieser Politik, als auch die Mittel, deren man sich zum Erreichen dieses Ziels bedient. Werden etwa territoriale Integrität und Souveränitäts- wahrung als Kernwerte nationaler Sicherheit angenommen, ent- spricht dies einer normativen politischen Ausrichtung. Im Vorder- grund steht damit die Bewahrung des bestehenden National- staats und nicht beispielsweise die Bildung

Walter Lippmann

264

Ventilatory Control in ALS  

PubMed Central

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to “fight back” via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients. PMID:23692930

Nichols, Nicole L.; Van Dyke, J.; Nashold, L.; Satriotomo, I.; Suzuki, M.; Mitchell, G.S.

2015-01-01

265

Performance of NiCrAlY Coatings Deposited by Oxyfuel Thermal Spraying in High Temperature Chlorine Environment  

NASA Astrophysics Data System (ADS)

A microcrystalline Ni-22Cr-10Al-1Y (wt.%) coating was deposited on AISI 304 stainless steel by the oxyfuel thermal spray technique. The deposited coating was subjected to heat treatment to improve the microstructure characteristics and its corresponding high-temperature properties. The isothermal high-temperature corrosion behavior at 650 and 700 °C in synthetic air and in the presence of 1% Cl2 was investigated using thermogravimetric analysis, x-ray diffraction, and scanning electron microscopy with energy-dispersive x-ray spectroscopy. The results indicated that the deposited NiCrAlY coating possessed acceptable oxidation-corrosion resistance at 650 °C owing to the formation of extensive amounts of the protective oxide of Cr2O3; NiO and a lesser amount of a Cr1.12 Ni2,88 metallic phase are also formed. At 700 °C, the coating lost its protective characteristic because of the excessive consumption of thermodynamically stable phases by oxidation-chlorination process. In this case, the steel base and the coating were attacked by chlorine during the exposure time; the mass gain of the NiCrAlY coating was slightly higher and provided only a limited protection up to 11 h; thereafter, breakdown of the layer of oxides occurred and this is attributed to the formation of non-protective oxides mainly ?-Fe2O3 and Fe21.33O32 and the depletion of chromium.

Habib, K. A.; Damra, M. S.; Carpio, J. J.; Cervera, I.; Saura, J. J.

2014-10-01

266

Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel  

NASA Astrophysics Data System (ADS)

The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the laser joints were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), Vickers microhardness (HV0.2) and tensile testing techniques. The results showed that the NiTi-NiTi laser joint reached about 63% of the ultimate tensile strength of the as-received NiTi wire (i.e. 835 MPa) with rupture strain of about 16%. This joint also enabled the possibility to benefit from the pseudo-elastic properties of the NiTi component. However, tensile strength and ductility decreased significantly after dissimilar laser welding of NiTi to stainless steel due to the formation of brittle intermetallic compounds in the weld zone during laser welding. Therefore, a suitable modification process is required for improvement of the joint properties of the dissimilar welded wires.

Mirshekari, G. R.; Saatchi, A.; Kermanpur, A.; Sadrnezhaad, S. K.

2013-12-01

267

ALS2 mutations  

PubMed Central

Objective: To determine the genetic etiology in 2 consanguineous families who presented a novel phenotype of autosomal recessive juvenile amyotrophic lateral sclerosis associated with generalized dystonia. Methods: A combination of homozygosity mapping and whole-exome sequencing in the first family and Sanger sequencing of candidate genes in the second family were used. Results: Both families were found to have homozygous loss-of-function mutations in the amyotrophic lateral sclerosis 2 (juvenile) (ALS2) gene. Conclusions: We report generalized dystonia and cerebellar signs in association with ALS2-related disease. We suggest that the ALS2 gene should be screened for mutations in patients who present with a similar phenotype. PMID:24562058

Schneider, Susanne A.; Carr, Lucinda; Deuschl, Guenther; Hopfner, Franziska; Stamelou, Maria; Wood, Nicholas W.; Bhatia, Kailash P.

2014-01-01

268

Amyotrophic Lateral Sclerosis (ALS)  

MedlinePLUS

... with ALS may eventually consider forms of mechanical ventilation (respirators). What is the prognosis? Regardless of the ... the muscles of the respiratory system weaken. Although ventilation support can ease problems with breathing and prolong ...

269

What Is ALS?  

MedlinePLUS

... cells in the brain and the spinal cord. Motor neurons reach from the brain to the spinal cord ... throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When ...

270

Genetic Testing for ALS  

MedlinePLUS

... Share Print Familial Amyotrophic Lateral Sclerosis (FALS) and Genetic Testing By Deborah Hartzfeld, MS, CGC, Certified Genetic ... guarantee a person will develop symptoms of ALS. Genetic Counseling If there is more than one person ...

271

Leakage current behaviors of Al/ZrO2/Al and Al/YSZ/Al devices  

NASA Astrophysics Data System (ADS)

The leakage current behaviors of Al/ZrO2/Al and Al/yttria stabilized zirconia (YSZ)/Al devices are investigated for resistive random access memory (RRAM) applications. A silicon oxide layer (450 nm) is first formed on a Si wafer by thermal oxidation. Onto it an Al bottom electrode (270 nm), a ZrO2 or YSZ nano-film (75 nm), and an Al top electrode (270 nm) are sequentially deposited by sputtering. These RRAM devices exhibit ohmic behaviors in the low-field region, while Schottky and Poole–Frenkel emissions take over in the high-field regions. Both the Schottky and trap barrier levels are decreased when monoclinic ZrO2 is replaced by cubic YSZ in the metal/oxide/metal structure. This is attributed not only to the higher symmetry crystal structure and lower binding energy of YSZ, but also to the formation of more oxygen vacancies and their re-distribution associated with yttria doping.

Yeh, Tsung-Her; Lin, Ruei-De; Cherng, Bo-Ruei; Cherng, Jyh-Shiarn

2015-01-01

272

Characterization and optimization of pulse electrodeposition of Ni/nano-Al2O3 composite coatings  

NASA Astrophysics Data System (ADS)

Nickel/nano-Al2O3 composite coatings produced by the pulse electrodeposition method and the influence of pulse parameters, i.e., pulse frequency, duty cycle, and current density on the microstructure, hardness, and corrosion resistance, were critically investigated on an AISI 1018 mild steel specimen electroplated in a Watt's type bath. The experiments were carried out with different combinations of pulse parameters using Taguchi's L27 orthogonal array, and 27 trials were conducted to study the effect of pulse parameters in view to maximize the hardness of the specimen. The assessment results clearly reveal that the specimen exhibits the maximum hardness at the pulse frequency of 20 Hz, duty cycle of 30%, and peak current density of 0.4 A/cm2, which are designated as the optimal parameters herein. Furthermore, the influences of those optimized pulse parameters over the microstructure and corrosion resistance were investigated, and some conclusions were drawn. Also, from the ANOVA examination, it is clear that duty cycle is predominant in affecting the hardness, while current density has relatively low impact.

Jegan, A.; Venkatesan, R.

2013-05-01

273

Rapidly solidified NiAl and FeAl  

NASA Technical Reports Server (NTRS)

Melt spinning was used to produce rapidly solidified ribbons of the B2 intermetallics NiAl and FeAl. Both Fe-40Al and Fe-45Al possessed some bend ductility in the as spun condition. The bend ductility of Fe-40Al, Fe-45Al, and equiatomic NiAl increased with subsequent heat treatment. Heat treatment at approximately 0.85 T (sub m) resulted in significant grain growth in equiatomic FeAl and in all the NiAl compositions. Low bend ductility in both FeAl and NiAl generally coincided with intergranular failure, while increased bend ductility was characterized by increasing amounts of transgranular clevage fracture.

Gaydosh, D. J.; Crimp, M. A.

1985-01-01

274

Rapidly solidified NiAl and FeAl  

NASA Technical Reports Server (NTRS)

Melt spinning was used to produce rapidly solidified ribbons of the B2 intermetallics NiAl and FeAl. Both Fe-40Al and Fe-45Al possessed some bend ductility in the as spun condition. The bend ductility of Fe-40Al, Fe-45Al, and equiatomic NiAl increased with subsequent heat treatment. Heat treatment at approximately 0.85 T (sub m) resulted in significant grain growth in equiatomic FeAl and in all the NiAl compositions. Low bend ductility in both FeAl and NiAl generally coincided with intergranular failure, while increased bend ductility was characterized by increasing amounts of transgranular cleavage fracture.

Gaydosh, D. J.; Crimp, M. A.

1984-01-01

275

Determination of damage functions for the pitting of AISI type 403 blade alloy and ASTM A470/471 disk alloy  

NASA Astrophysics Data System (ADS)

The prediction of pitting accumulation on turbine blades and disks is of particular importance to predict localized corrosion damages in low pressure (LP) steam turbines. Damage Function Analysis (DFA) and Deterministic Extreme Value Statistics (DEVS) have been employed to predict the pitting damage on AISI Type 403 stainless steel (SS) blade alloy and ASTM A470/471 disk steel in simulated LP steam turbine environments within the phase transition zone. The passivity properties of Type 403 SS and A470/471 steel in the passive regions, including defect type, defect concentration in the barrier film, barrier film thickness, and the steady-state current density, agree with the predictions of the Point Defect Model (PDM) for an n-type semiconductor. Optimization of the PDM based impedance model on the experimental electrochemical impedance data has yielded a set of parameter values that can be used to predict the barrier film growth on Type 403 SS in deaerated borate buffer solution ( pH = 8.2) at ambient temperature. Experimental relationships between the breakdown potential and chloride activity, pH, temperature, and potential scan rate have demonstrated the applicability of the PDM for describing passivity breakdown on Type 403 SS and A470/471 steel. The obtained parameter values were used to calculate the breakdown potential, induction time, and their distributions, via the PDM, which represents the first quantitative characterization of the passivity breakdown behavior on Type 403 SS. Pitting damage functions for Type 403 SS have been experimentally determined for the first time. However, low pit density on A470/471 steel led to insufficient pit numbers on the 1.27 cm2 surface for the effective determination of damage functions. DEVS has been demonstrated by predicting the average maximum pit depth for 750 hours from short-term (24 hours and 240 hours) maximum pit depth data on Type 403 SS in deaerated buffer solution with 0.10 M NaCl at an applied potential of 0.090 VSCE and on A470/471 steel in the solution with 0.028 M NaCl at 0.058 VSCE. To the author's knowledge, the work reported in this dissertation represents the first instance in which DEVS has been used to predict the accumulation of pitting damage on LP steam turbine alloys, thereby heralding a new era in the prediction of corrosion damage in these systems.

Zhang, Yancheng

276

Negative ion photodetachment spectroscopy of the Al3O2 , Al3O3 , Al4Ox , Al5Ox (x = 35), Al6O5 , and Al7O5 clusters  

E-print Network

Negative ion photodetachment spectroscopy of the Al3O2 , Al3O3 , Al4Ox , Al5Ox (x = 3­5), Al6O5 , and Al7O5 clusters Giovanni Meloni, Michael J. Ferguson and Daniel M. Neumark Department of Chemistry as an Advance Article on the web 9th September 2003 The Al3O2 , Al3O3 , Al4Ox , Al5Ox (x ¼ 3­5), Al6O5 , and Al7

Neumark, Daniel M.

277

Al Qaeda Training Manual  

NSDL National Science Digital Library

The first resource is a US Department of Justice release of portions of an English translation of the Al Qaeda training manual located by police in Manchester, England during a search of an Al Qaeda member's home. The manual was found in a computer file described as "the military series" related to the "Declaration of Jihad." The cover and excerpts from the 12 chapters can be viewed as a .pdf file. Content of the text includes religious commentary, organizational tactics, guidelines for member selection, techniques for spying, and security measures. The DOJ does not provide the entire document because it does not want to encourage terrorism.

2001-01-01

278

MDA ALS Caregiver's Guide  

MedlinePLUS

... cure.” And it’s really hard work. It involves learning about new tasks and equipment, while going through the emotions that arise when a loved one has a progressive, debilitating illness. These pages contain practical and emotional strategies for being an effective caregiver. The MDA ALS ...

279

Ausbildung als zentrale Aufgabe  

NASA Astrophysics Data System (ADS)

Anders als Lesen und Schreiben zählen Grundkenntnisse in Statistik heute noch nicht zu den Voraussetzungen einer sinnvollen Teilhabe am Sozialgeschehen. Und auch in der akademischen Statistik-Ausbildung gibt es noch einiges zu tun. Das vorliegende Kapitel zeichnet die Geschichte dieser akademischen Ausbildung an deutschen Universitäten nach dem zweiten Weltkrieg nach, stellt aktuelle Defizite vor und weist auf mögliche Verbesserungen hin.

Krämer, Walter; Schmerbach, Sibylle

280

Smith et al Supporting Information  

E-print Network

Smith et al 1 Supporting Information for Smith et al. 2006, PLoS Computational Biology 2:e161-hyperpallium apicale; HF-hippocampal formation, and M-mesopallium. #12;Smith et al 2 FigureS2,nolinkswerefoundbetweenelectrodesindifferentbirds,andnolinkswerefoundintothesoundstimulusvariable. CombinedAnalysisofAllBirds'ElectrodesPlusSound #12;Smith et al 3 Analysis of Data from Subsections

Jarvis, Erich D.

281

/Al-Si Composite  

NASA Astrophysics Data System (ADS)

The cyclic fatigue characteristics of spray-deposited SiCp/Al-Si composite were investigated in comparison with the unreinforced Al-Si alloy. The as-extruded specimens were cyclically deformed with fully reversed loading under a range of total strain amplitudes. The results show that the cyclic response characteristics for the reinforced and unreinforced materials are similar to each other. Both the composite and matrix alloys display cyclic hardening under total strain amplitude of 0.35-0.5%. Otherwise, the composite exhibits higher degree of strain hardening than that of the matrix alloy. Dislocation substructure developed during cyclic deformation was analyzed using transmission electron microscopy. The discrepancy between dislocation substructures obtained from processing compared to its development during cyclic strain loading is thought to give rise to the observed cyclic stress response behavior. Fractographic analysis shows that particle/matrix debonding and particle cracking are the main mechanisms of failure in the SiC particle-reinforced composite.

Li, Wei; Chen, Jian; Hu, Yongle; Cong, Li; Sun, YouPing; Yang, JiMing

2014-08-01

282

Al Parker: American Illustrator  

NSDL National Science Digital Library

This tribute to Al Parker, the noted magazine illustrator and artist, was fashioned from extensive holdings at the Washington University Library in St. Louis. Known as "The Dean of Illustrators," Al Parker attended school at the St. Louis School of Fine Arts at Washington University and went on to become of the most prolific and important American illustrators of the twentieth century. Parker was best-known for his modernist deployment of line, patterning, and bold, flat colors, which helped shape the general "look" of the period from the 1930s to the 1960s. Using short clips of Parker's original illustrations and drawings, this exhibit offers a glimpse into his work and contributions to the medium. Of particular interest is the section devoted to Parker's famous "Mother-Daughter" covers for the Ladies Home Journal, which began in 1939 and ran for 17 years.

283

ALS insertion devices  

SciTech Connect

The Advanced Light Source (ALS), the first US third generation synchrotron radiation source, is currently under construction at the Lawrence Berkeley Laboratory. The low-emittance, 1.5 GeV electron storage ring and the insertion devices are specifically designed to produce high brightness beams in the UV to soft X-Ray range. The planned initial complement of insertion devices includes four 4.6 m long undulators, with period lengths of 3.9 cm, 5.0 cm (2) and 8.0 cm, and a 2.9 m long wiggler of 16 cm period length. Undulator design is well advanced and fabrication has begun on the 5.0 cm and 8.0 cm period length undulators. This paper discusses ALS insertion device requirements; general design philosophy; and design of the magnetic structure, support structure/drive systems, control system and vacuum system. 18 refs., 9 figs., 5 tabs.

Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

1990-11-01

284

Partnerwahl als konsensuelle Entscheidung  

Microsoft Academic Search

Zusammenfassung  Die vorliegende Studie setzt unsere Analysen der Kontaktierungsprozesse im Online-Dating (KZfSS 2\\/2009) fort. Da Paarbeziehungen\\u000a auf einer konsensuellen Entscheidung für eine gemeinsame Beziehung beruhen, widmet sich der vorliegende Beitrag der Frage,\\u000a wie Männer und Frauen auf Erstkontaktversuche reagieren. Die Datenstruktur von Online-Dating-Börsen bietet eine einzigartige\\u000a Chance, soziologisch im Detail zu rekonstruieren, wie Paarbeziehungen als konsensuelle Wahlhandlung nach und nach entstehen.

Florian Schulz; Jan Skopek; Hans-Peter Blossfeld

2010-01-01

285

A progress report on the use of electrochemical noise to investigate the effects of zebra mussel attachment on the corrosion resistance of AISI Type 304 stainless steel and carbon steel in lake water  

SciTech Connect

The electrochemical noise technique was used to determine the effect of zebra mussel settlement on the corrosion performance of AISI Type 304 stainless steel and carbon steel (ASTM A53 Grade B). These materials represent alloys commonly used for handling untreated Great Lakes water at Ontario Hydro`s power generating plants. This work was motivated by a concern that zebra mussel settlement will lead to accelerated attack of these materials as a result of the establishment of stable crevice conditions and the growth of corrosion influencing anaerobic sulfate-reducing bacteria (SRB). Corrosion monitoring was carried out in a field test facility that uses the same untreated Lake Erie water as Ontario Hydro`s Nanticoke Thermal Generating Station. The test program extended from May through December 1993. During this period, a number of electrochemical parameters were monitored simultaneously, including coupling current, electrochemical potential noise (EPN), electrochemical current noise (ECN), degree of localization (DoL), and resistance noise (R{sub n}). Differences were observed in the performance of the control samples and the samples to which mussels were attached. The results for the AISI Type 304 stainless steel suggested that over the period monitored, mussel attachment reduced corrosion activity. Similarly, signals from carbon steel, samples exposed to mussels, although initially displaying relatively high corrosion rates, exhibited less corrosion damage than did control samples over the longer term. The reason for this difference in performance is not known but is considered to have resulted from a change in the surface environment as a result of mussel attachment, which appeared to diminish corrosion. One possible explanation may be the generation of inhibitive species by the mussels.

Brennenstuhl, A.M.; Sim, B. [Ontario Hydro Technologies, Toronto, Ontario (Canada); Claudi, R. [Ontario Hydro, Toronto, Ontario (Canada). Environmental Dept.

1996-12-31

286

26Al measurements with VERA  

NASA Astrophysics Data System (ADS)

The Vienna Environmental Research Accelerator (VERA) is a 3-MV Pelletron tandem mass spectrometer system. Since July 1996, extensive tests with 26Al detection were performed. Systematic investigations of reproducibility, transmission, overall efficiency etc. are necessary for a new facility such as VERA in order to come up with reliable results. To this end several different 26Al standards with an 26Al/ 27Al isotopic ratio between 5 × 10 -10 and 1 × 10 -12 were used. The results of these investigations revealed no systematic deviation beyond counting statistics. In order to determine the cross section for the 27Al(n,2n) 26Al reaction Al-metal samples with 26Al produced from neutron irradiation were measured and compared with 26Al standards.

Wallner, A.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.; Vonach, H.; Wild, E.

1998-04-01

287

Frequently Asked Questions about ALS and the ALS Registry  

MedlinePLUS

... Can a researcher access National ALS Registry data? How will you be sure that you have as many persons ... National ALS Registry web site. Back to Top How will you be sure that you have as many persons ...

288

The AISI direct steelmaking program  

SciTech Connect

After six months of operation of the pilot plant, the viability of in-bath smelting combined with a high level of post combustion has been demonstrated, and the opportunity exists for an early commercialization of the direct ironmaking part of the process while we continue to research direct steelmaking. The program should be of equal interest to integrated and electric furnace producers. Smelting of ore provides virgin iron units. Additionally, the process has the flexibility of melting scrap and varying the ore-to-scrap ratio over wide ranges. This process does not require coke, thus eliminating the cokemaking operation, a major source of environmental concern.

Aukrust, E. (LTV Steel Co., Inc., Cleveland, OH (United States)); Downing, K.B. (Inland Steel Flat Products Co. (United States))

1991-01-01

289

Amyotrophic Lateral Sclerosis (ALS)  

NSDL National Science Digital Library

This patient education program explains amyotrophic lateral sclerosis (ALS or Lou Gehrig's Disease) including the causes, symptoms, diagnosis and treatment options. This resource is a MedlinePlus Interactive Health Tutorial from the National Library of Medicine, designed and developed by the Patient Education Institute. NOTE: This tutorial requires a special Flash plug-in, version 4 or above. If you do not have Flash, you will be prompted to obtain a free download of the software before you start the tutorial. You will also need an Acrobat Reader, available as a free download, in order to view the Reference Summary.

Patient Education Institute

290

Al Jazirah, Sudan  

NASA Technical Reports Server (NTRS)

Al Jazirah (also Gezira) is one of the 26 states of Sudan. The state lies between the Blue Nile and the White Nile in the east-central region of the country. It is a well populated area suitable for agriculture. The area was at the southern end of Nubia and little is known about its ancient history and only limited archaeological work has been conducted in this area. The region has benefited from the Gezira Scheme, a program to foster cotton farming begun in 1925. At that time the Sennar Dam and numerous irrigation canals were built. Al Jazirah became the Sudan's major agricultural region with more than 2.5 million acres (10,000 km) under cultivation. The initial development project was semi-private, but the government nationalized it in 1950. Cotton production increased in the 1970s but by the 1990s increased wheat production has supplanted a third of the land formerly seeded with cotton.

The image was acquired December 25, 2006, covers an area of 56 x 36.4 km, and is located near 14.5 degrees north latitude, 33.1 degrees east longitude.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

2008-01-01

291

Al(+)-ligand binding energies  

NASA Technical Reports Server (NTRS)

Ab initio calculations are used to optimize the structure and determine the binding energies of Al(+) to a series of ligands. For Al(+)-CN, the bonding was found to have a large covalent component. For the remaining ligands, the bonding is shown to be electrostatic in origin. The results obtained for Al(+) are compared with those previously reported for Mg(+).

Sodupe, M.; Bauschlicher, Charles W., Jr.

1991-01-01

292

Studies of 27Al NMR in EuAl4  

NASA Astrophysics Data System (ADS)

EuAl4 orders antiferromagnetically at TN ? 16 K with an effective magnetic moment of 8.02 ?B. In the paramagnetic phase, the magnetic susceptibility of EuAl4 follows the Curie-Weiss law with a positive Curie-Weiss temperature ?P = +14 K. The antiferromagnetic state is changed into the field induced ferromagnetic state at a critical field Hc of approximately 2 T. In order to microscopically investigate the magnetic and electronic properties in EuAl4, the NMR measurements of EuAl4 have been carried out at temperatures between 2 and 300 K, applying an external magnetic field of approximately 6.5 T. The 27Al NMR spectra corresponding to Al(I) and Al(II) sites are obtained. From the 27Al NMR spectra, the isotropic part Kiso and anisotropic part Kaniso of Knight shift, and nuclear quadrupole frequncy ?Q are obtained. The Kiso and Kaniso shift to negative side with decreasing temperature due to the RKKY interaction. These temperature dependences follow the Curie-Weiss law with ?P = +14 K, which is consistent with that of the magnetic susceptibility. From the K – ? plot, the values of the hyperfine fields Hhf_iso and Hhf_aniso are -3.231 and -0.162 kOe/?B for Al(I) site, and -1.823 and -0.264 kOe/?B for Al(II) site, respectively. The values of ?Q of 27Al nucleus for Al(I) and Al(II) sites are approximately 0.865 and 0.409 MHz, respectively. The nuclear relaxation time T1 of 27Al NMR for both sites is almost constant in the paramagnetic phase, while the value of 1/T1 is abruptly decreased in the ordered ferromagnetic state.

Niki, H.; Nakamura, S.; Higa, N.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; ?nuki, Y.; Harima, H.

2015-03-01

293

Al Mashriq: Lebanon  

NSDL National Science Digital Library

Part of the Al-Mashriq online Web resource for countries located in the Levant, this site is devoted to providing a host of materials, thematically organized, about the country of Lebanon. Persons seeking to read a bit about Lebanon's early history will want to read the first chapter of Kamal Salibi's "A House of Many Mansions-The History of Lebanon," which is provided here. For those looking for a geographic orientation to the landscape of Lebanon, an interactive map provides a number of photographs and brief remarks on various important cities and cultural sites, such as Beirut and the Roman temples at Baalbak. Along with these sections, the site also offers thematic sections devoted to education, food, maps, money, politics, and religion that will be useful to those students looking for background information on Lebanon.

294

Descenso al Infierno de VenusDescenso al Infierno de VenusDescenso al Infierno de VenusDescenso al Infierno de Venus Manuel Alfonseca  

E-print Network

Descenso al Infierno de VenusDescenso al Infierno de VenusDescenso al Infierno de VenusDescenso al Infierno de Venus Manuel Alfonseca #12;Manuel Alfonseca 2 #12;Descenso al infierno de Venus 3 Descenso al infierno de Venus Manuel Alfonseca RESERVADOS TODOS LOS DERECHOS. Salvo usos razonables destinados al

Alfonseca, Manuel

295

Effects of Si content on microstructure and mechanical properties of TiAlN/Si3N4-Cu nanocomposite coatings  

NASA Astrophysics Data System (ADS)

TiAlN/Si3N4-Cu nanocomposite coatings of various Si content (0-5.09 at.%) were deposited on AISI-304 stainless steel by DC reactive magnetron sputtering technique. The chemical composition, microstructure, mechanical and tribological properties of these coatings were systematically investigated by means of X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), nanoindentation tester, a home-made indentation system, a scratch tester and a wear tester. Results indicated that with increasing Si content in these coatings, a reduction of grain size and surface roughness, a transformation of the (1 1 1) preferred orientation was detected by XRD and FESEM. Furthermore the hardness of these coatings increase from 9.672 GPa to 18.628 GPa, and the elastic modulus reveal the rising trend that increase from 224.654 GPa to 251.933 GPa. However, the elastic modulus of TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content dropped rapidly and changed to about 180.775 GPa. The H3/E2 ratio is proportional to the film resistance to plastic deformation. The H3/E2 ratio of the TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content possess of the maximum of 0.11 GPa, and the indentation test indicate that few and fine cracks were observed from its indentation morphologies. The growth pattern of cracks is mainly bending growing. The present results show that the best toughness is obtained for TiAlN/Si3N4-Cu nanocomposite coating containing 3.39 at.% Si content. In addition, the TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content also has good adhesion property and superior wear resistance, and the wear mechanism is mainly adhesion wear.

Feng, Changjie; Hu, Shuilian; Jiang, Yuanfei; Wu, Namei; Li, Mingsheng; Xin, Li; Zhu, Shenglong; Wang, Fuhui

2014-11-01

296

Dry Sliding Wear Behavior of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy  

NASA Astrophysics Data System (ADS)

Dry sliding wear tests were performed for Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy against AISI 52100 steel under the loads of 50 to 250 N at 298 K to 873 K (25 °C to 600 °C). The wear behavior of the alloy varied with the change of test conditions. More or less tribo-oxides TiO2 and Fe2O3 formed on worn surfaces under various conditions. At lower temperature [298 K to 473 K (25 °C to 200 °C)], less and scattered tribo-oxide layers did not show wear-reduced effect. As more number of and continuous tribo-oxide layers appeared at higher temperatures [773 K to 873 K (500 °C to 600 °C)], the wear rate would be substantially reduced. It can be suggested that Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy possessed excellent wear resistance at 773 K to 873 K (500 °C to 600 °C). The wear-reduced effect of tribo-oxides seemed to depend on the appearance of Fe2O3 and the amount of tribo-oxides.

Wang, L.; Zhang, Q. Y.; Li, X. X.; Cui, X. H.; Wang, S. Q.

2014-04-01

297

Wear testing under high load conditionsThe effect of ``anti-scuff'' additions to AISI 3135, 52100 and 9310 steels introduced by ion implantation and ion beam mixing  

NASA Astrophysics Data System (ADS)

There is a need to eliminate the sudden onset of severe adhesive wear ("scuffing") in high performance hardened steels (e.g. AISI 9310) under arduous load conditions. We have investigated the friction and wear behavior of three ion implanted and ion beam mixed steels under simulated scuffing conditions using a Falex friction and wear tester. This machine enabled tests to be carried out at a load of 700 lb (318 kg), corresponding to a mean contact pressure of approximately 20 000 psi (i.e., 1×10 8 N/m 2) which was sufficient to induce scuffing. A series of lower load tests at 200 lb (91 kg) load (5.2 × 10 7 N/m 2) enabled the longer term wear performance of various ion/substrate combinations to be measured. The frictional force experienced during wear testing was used to assess the degree of scuffing, and the amount of material worn away was measured on the Falex tester or by subsequent weight loss determinations, depending on the type of test. The following ions were implanted: C +, N +, P +, Ti +, Cr +, Mo +, and Ta +, chosen in order to evaluate the effects of intermetallic additions (C, N, P), alloys elements (Ti, Cr), and anti-scuff elements (Mo, Ta). In addition some thin ( ˜1000 Å) vacuum evaporated layers of Si, V, Ni, Nb, Sn, Mo, Ta and W were prepared, and in some cases intermixed with N + ions at a fluence of typically 2×10 17/cm 2, to compare with the effects of ion implantation. Under the low load conditions the wear rate of AISI 3135 steel (1.5% Ni, 0.65% Cr alloy tool steel) was found to be reduced by a factor 3 as a result of N + implantation under low load, in agreement with previous work reported elsewhere, whereas other ions gave inconclusive results. The 52100 steel (a through-hardened martensitic bearing steel) showed marked improvements after Ti + implantation, revealing a sensitivity to fluence which correlated with known dry sliding behaviour of this steel modified by titanium implantations. Ta + and Mo + implantations into 9310 steel (a case-hardened gear steel with 3.0% Ni, 1.4% Cr and 0.55% Mn) reduced the wear rate (in ?g per second) under the low load parameters from 4.2 to 0.15 and 0.26 respectively. Under simulated scuffing, Ta + was effective whereas Mo + was not. SEM examination of the implanted AISI-9310 steel wear pins tested to 200 lb (91 kg) showed extensive smoothing in the implanted worn zones, implying a different wear process. On all the steels, mixed overlayers showed improved friction and wear behavior compared to unmixed layers. The results are discussed in terms of the probable influence of the various added elements on the metallurgical wear mechanisms of the respective steels.

Hartley, N. E. W.; Hirvonen, J. K.

1983-05-01

298

AL Amyloidosis with Renal Involvement  

Microsoft Academic Search

Primary (AL amyloidosis) is a systemic disease characterized by an amyloid deposition process in many organs, with unsatisfactory survival of patients. The monoclonal light chains form the fibrils that deposit and accumulate in tissues. Renal involvement is very frequent in AL amyloidosis and could lead to development of nephrotic syndrome followed by the renal failure in many cases. Classic therapeutic

Romana Ryšavá

2007-01-01

299

Characteristics of CeCoIn5/Al/AlOx/Nb and CeCoIn5/Al/AlOx/Al Tunnel Junctions  

SciTech Connect

We report characteristics of CeCoIn{sub 5}/Al/AlO{sub x}/Nb and CeCoIn{sub 5}/Al/AlO{sub x}/Al tunnel junctions fabricated on the (0 0 1) surface of CeCoIn{sub 5} crystal platelets. The main result of this work is the observation of a low Josephson current (as compared with that expected from the Ambegaokar-Baratoff formula), which is consistent with idea that the order parameter in the heavy-fermion superconductor CeCoIn{sub 5} has unconventional pairing symmetry.

Petrovic, C.; Nevirkovets, I.P.; Chernyashevskyy, O.; Hu, R.; Ketterson, J.B.; Sarma, B.K.

2009-03-03

300

Allegato "B" DOMANDA DI PARTECIPAZIONE AL CONCORSO DI AMMISSIONE AL  

E-print Network

IN ROBOTICA, NEUROSCIENZE, NANOTECNOLOGIE E SCOPERTA FARMACI IN COLLABORAZIONE CON LA FONDAZIONE IIT Si prega'ammissione al Corso di Dottorato di Ricerca in Robotica, Neuroscienze, Nanotecnologie e Scoperta Farmaci

Sandini, Giulio

301

(12) United States Patent Harvey et al.  

E-print Network

(12) United States Patent Harvey et al. (54) ANALYZING RETURN ON INVESTMENT OF ADVERTISING US 2009/0259518 Al Oct. 15,2009 Int. Cl. G06F 17/30 (2006.01) G07G 1/00 (2006.01) U.S. Cl et al. 911980 Block et al. 511982 Eskin et al. 1111982 Barber et al. 711985 Block et al. 111996

Shamos, Michael I.

302

ALS ACT (Accelerated Therapeutics), The ALS Association, Northeast ALS Consortium, and the ALS Finding A Cure Foundation  

E-print Network

pharmaceutical, biotherapeutic/biotechnology companies, academic members of the NEALS Consortium, and ALS through NEALS: Project Management Grants & Contracts Management Data Management Study Monitoring Document Review, and Ongoing Site Management Site Trainings: Good Clinical Practice, Regulatory Compliance

MacMillan, Andrew

303

In Memory of Al Cameron  

E-print Network

Al Cameron, who died recently (October 3, 2005) at 80, was one of the giants in astrophysics. His insights were profound and his interests were wide-ranging. Originally trained as a nuclear physicist, he made major contributions in a number of fields, including nuclear reactions in stars, nucleosynthesis, the abundances of the elements in the Solar System, and the origin of the Solar System and the Moon. In 1957, Cameron and, independently, Burbidge, Burbidge, Fowler and Hoyle, wrote seminal papers on nuclear astrophysics. Most of our current ideas concerning element formation in stars have followed from those two pioneering and historical works. Al also made many contributions in the field of Solar System physics. Particularly noteworthy in this regard was Cameron's work on the formation of the Moon. Al was also a good friend and mentor of young people. Al Cameron will be missed by many in the community both for his scientific contributions and for his friendship.

John J. Cowan; James W. Truran

2006-11-27

304

Developmental Cell Abbott et al.  

E-print Network

seam cell nuclei. #12;#12;Developmental Cell September Abbott et al. Supplemental Experimental Procedures Detection expression is observed at the L1 stage in multiple cell types, including seam cells and neurons (n). (B, D

Bartel, David

305

Comparing the Thermodynamic Behaviour of Al(1)+ZrO2(s) to Al(1)+Al2O3(s)  

NASA Technical Reports Server (NTRS)

In an effort to better determine the thermodynamic properties of Al(g) and Al2O(g). the vapor in equilibrium with Al(l)+ZrO2(s) was compared to the vapor in equilibrium with Al(l)+Al2O3(s) over temperature range 1197-to-1509K. The comparison was made directly by Knudsen effusion-cell mass spectrometry with an instrument configured for a multiple effusion-cell vapor source (multi-cell KEMS). Second law enthalpies of vaporization of Al(g) and Al2O(g) together with activity measurements show that Al(l)+ZrO2(s) is thermodynamically equivalent to Al(l)+Al2O3(s), indicating Al(l) remained pure and Al2O3(s) was present in the ZrO2-cell. Subsequent observation of the Al(l)/ZrO2 and vapor/ZrO2 interfaces revealed a thin Al2O3-layer had formed, separating the ZrO2-cell from Al(l) and Al(g)+Al2O(g), effectively transforming it into an Al2O3 effusion-cell. This behavior agrees with recent observations made for Beta-NiAl(Pt) alloys measured in ZrO2 effusion-cell.

Copland, Evan

2004-01-01

306

Corrosion Behavior of Al-Al3Ni and Al-Al2Cu Functionally Graded Materials Fabricated by a Centrifugal Method  

NASA Astrophysics Data System (ADS)

Intermetallic compounds, such as Al3Ni and Al2Cu, are effective for enhancing the mechanical properties of an alloy. Al-Al3Ni and Al-Al2Cu functionally graded materials (FGMs) might be attractive materials for advanced materials. Al-Al3Ni and Al-Al2Cu FGMs were fabricated by a centrifugal method; the centrifugal method is an extremely effective method for fabricating FGMs. Al-Al3Ni and Al-Al2Cu FGMs that had a graded distribution of intermetallic compounds could be produced by this in-situ centrifugal method. Particle size, particle shape and the distribution of intermetallic compounds were controlled by varying the content of the alloy element (Ni, Cu) in the master alloy, the cooling rate in casting and the gravity number. The casting mechanism is explained in terms of the microstructures of the Al-Al3Ni and Al-Al2Cu FGMs fabricated by this method. The corrosion behavior of the FGMs was investigated by electrochemical analysis. Polarization curves of the FGMs in a borate solution were measured by a potentiodynamic method. The presence of Al2Cu exerted a larger effect on the corrosion behavior of the FGMs than Al3Ni. Analysis of the polarization curve parameters was effective for evaluating the corrosion resistance of the FGMs.

Noda, Kazuhiko; Miyahara, Keita; Watanabe, Yoshimi

2008-02-01

307

77 FR 73732 - In the Matter of Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa'al...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Front, Jabhat al- Nusrah, Jabhet al-Nusra, The Victory Front, Al Nusrah Front...aka Jabhat al-Nusrah, aka Jabhet al-Nusra, aka The Victory Front, aka Al...Front, Jabhat al-Nusrah, Jabhet al-Nusra, The Victory Front, Al Nusrah...

2012-12-11

308

ALS Association's Patient Bill of Rights for People Living with ALS  

MedlinePLUS

... Caregivers Newly Diagnosed ALS Registry Military Veterans Augmentative Communication Caregivers Resources ALS Insight Newsletter Living with ALS Manuals ALS Association Brochures Webinars Our Videos Factsheets Library Order Form Products to Aid in ...

309

Uranium cobalt tetraaluminide, UCoAl4.  

PubMed

The structure of UCoAl(4) can be viewed as a succession of atomic layers, with the compositions UCoAl and Al(3), that alternate along the c axis. The packing within the pure Al layer at z = 1/2 results from edge-sharing of triangles, squares and pentagons of Al atoms. Two successive Al(3) layers thus define pentagonal, square-based and trigonal prisms which are centred at z = 0 by the U, Co and remaining Al atoms. UCoAl(4) is a high-temperature phase that is only observed in as-cast samples. PMID:14712016

Stêpien-Damm, J; Tougait, O; Zaremba, V I; Noël, H; Troc, R

2004-01-01

310

AlN/Fe/AlN nanostructures for magnetooptic magnetometry  

SciTech Connect

AlN/Fe/AlN/Cu nanostructures with ultrathin Fe grown by sputtering on Si substrates are evaluated as probes for magnetooptical (MO) mapping of weak currents. They are considered for a laser wavelength of ??=?410?nm (3.02?eV) and operate at oblique light incidence angles, ?{sup (0)}, to enable detection of both in-plane and out-of-plane magnetization. Their performance is evaluated in terms of MO reflected wave electric field amplitudes. The maximal MO amplitudes in AlN/Fe/AlN/Cu are achieved by a proper choice of layer thicknesses. The nanostructures were characterized by MO polar Kerr effect at ?{sup (0)}???5° and longitudinal Kerr effect spectra (?{sup (0)}?=?45°) at photon energies between 1 and 5?eV. The nominal profiles were refined using a model-based analysis of the spectra. Closed form analytical expressions are provided, which are useful in the search for maximal MO amplitudes.

Lišková-Jakubisová, E., E-mail: liskova@karlov.mff.cuni.cz; Viš?ovský, Š. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 12116 Prague 2 (Czech Republic); Široký, P.; Hrabovský, D.; Pištora, J. [Nanotechnology Center, Technical University of Ostrava, 17. listopadu 15/2172, 70833 Ostrava Poruba (Czech Republic); Harward, I.; Celinski, Z. [Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, 1420 Austin Bluffs Pkwy., Colorado Springs, Colorado 80918 (United States)

2014-05-07

311

Dopant-Free GaN/AlN/AlGaN Radial Nanowire Heterostructures as High  

E-print Network

Dopant-Free GaN/AlN/AlGaN Radial Nanowire Heterostructures as High Electron Mobility Transistors, 2006 ABSTRACT We report the rational synthesis of dopant-free GaN/AlN/AlGaN radial nanowire-organic chemical vapor deposition (MOCVD). Transmission electron microscopy (TEM) studies reveal that the GaN/ AlN/AlGaN

Li, Yat

312

Modulation-doped (Al,Ga)As/AlAs superlattice: Electron transfer into AlAs  

SciTech Connect

A modulation-doped superlattice of n-(Al,Ga)As and undoped AlAs has been grown by molecular beam epitaxy. At cryogenic temperatures, electrons transfer into the undoped AlAs layers and enhanced mobilities as high as 1000 cm/sup 2//Vs are observed for the first time. It is shown that by properly accounting for the depth of the donor level in modulation-doped heterostructures reasonably good limits can be set on the gamma point conduction-band discontinuity at the heterojunction. It is found that this discontinuity is approximately 60--65% of the band-gap difference between the two alloys, in good agreement with other recent determinations.

Drummond, T.J.; Fritz, I.J.

1985-08-01

313

Microstructure Evolution and Mechanical Properties of Al/Al-Mg/Al composite sheet metals  

NASA Astrophysics Data System (ADS)

Two different types of aluminum alloys of AA1050 and AA5182 were used to manufacture Al/Al-Mg/Al composite sheet metals by roll bonding technology at room temperature. The composite sheet metals were annealed at 400 °C and carried out uniaxial tension tests to investigate mechanical properties. Macroscopic mechanical properties are strongly dependent on the volume (or thickness) fraction of two component layers. Microstructure and texture evolution were also investigated during roll bonding process. The AA1050 sheets located in the outer layer mainly consist of shear texture components and the AA5182 sheet located in the center layer consists of plane strain texture components. With differential speeds of the top and bottom rolls, roll bonding was also carried out. Elongation along the RD and TD was improved at a speed difference of approximately 10%-20%.

Cho, Jaehyung; Kim, Su-Hyeon; Kim, Hyoung-Wook; Lim, Cha-Yong; Kim, Eun-Young; Choi, Shi-Hoon

2011-08-01

314

Lynch et al. Proceedings 109  

E-print Network

Lynch et al. Proceedings 109 Insect­Fire Interactions in Yellowstone National Park: The Influence@fas.harvard.edu) Roy A. Renkin Yellowstone Center for Resources, P.O. Box 168, Yellowstone National Park, WY 82190 (307 of mountain pine beetle (Dendroctonus ponderosae Hopkins) activity within Yellowstone National Park, Wyoming

Moorcroft, Paul R.

315

AnnuAl report JAhresbericht  

E-print Network

AnnuAl report JAhresbericht rApport d'Activités 2010 #12;#12;1LE MOT DU RECTEUR LE MOT DU RECTEUR of laboratory space. This will change in the year 2011 with the inauguration of the LCSB building in Belval GOUVERNANCE RAPPORT ANNUEL 2010 LE CONSEIL DE GOUVERNANCE P. 05 L'�QUIPE RECTORALE P. 11 LES ORGANES

van der Torre, Leon

316

Transformer Abdullah Al-Otaibi  

E-print Network

Transformer Abdullah Al-Otaibi ID#242374 Section#2 Abstract- this is a brief description for transformer and how it works. I. DEFINITION A transformer is a device that transfers electrical energy from of the transformer in 1831. The transformer is used by Faraday only to demonstrate the principle of electromagnetic

Masoudi, Husain M.

317

Dynamic Modeling of ALS Systems  

NASA Technical Reports Server (NTRS)

The purpose of dynamic modeling and simulation of Advanced Life Support (ALS) systems is to help design them. Static steady state systems analysis provides basic information and is necessary to guide dynamic modeling, but static analysis is not sufficient to design and compare systems. ALS systems must respond to external input variations and internal off-nominal behavior. Buffer sizing, resupply scheduling, failure response, and control system design are aspects of dynamic system design. We develop two dynamic mass flow models and use them in simulations to evaluate systems issues, optimize designs, and make system design trades. One model is of nitrogen leakage in the space station, the other is of a waste processor failure in a regenerative life support system. Most systems analyses are concerned with optimizing the cost/benefit of a system at its nominal steady-state operating point. ALS analysis must go beyond the static steady state to include dynamic system design. All life support systems exhibit behavior that varies over time. ALS systems must respond to equipment operating cycles, repair schedules, and occasional off-nominal behavior or malfunctions. Biological components, such as bioreactors, composters, and food plant growth chambers, usually have operating cycles or other complex time behavior. Buffer sizes, material stocks, and resupply rates determine dynamic system behavior and directly affect system mass and cost. Dynamic simulation is needed to avoid the extremes of costly over-design of buffers and material reserves or system failure due to insufficient buffers and lack of stored material.

Jones, Harry

2002-01-01

318

Sobrevivir al cáncer: comer bien  

Cancer.gov

Sobrevivir al cáncer: comer bien Por el Instituto Nacional del Cáncer Bethesda, MD. - Más de 13 millones de personas que viven en Estados Unidos han recibido un diagnóstico de cáncer. Muchas de las personas que han tenido cáncer quieren seguir una

319

(12) United States Patent Reardan et al.  

E-print Network

(12) United States Patent Reardan et al. (54) SENSITIVE DRUG DISTRIBUTION SYSTEM AND METHOD (75 2004/0117205 Al Jun. 17,2004 (51) Int. Cl. G06Q 10/00 (2006.01) (52) U.S. Cl/231 4,976,351 A 1211990 Mangini et al. 5,737,539 A * 411998 Edelson et al. ................. 705/3 5

Shamos, Michael I.

320

(12) United States Patent Likourezos et al.  

E-print Network

(12) United States Patent Likourezos et al. (54) SYSTEM AND METHOD FOR AUTOMATICALLY EFFECTING Publication Data US 2002/0095376 Al Jul. 18, 2002 Related U.S. Application Data Continuation Altman et al. ................ 705/36 5,715,314 A 211998 Payne et al. 5,794,219 A 811998 Brown 5

Shamos, Michael I.

321

Identification of Candida albicans ALS2 and ALS4 and Localization of Als Proteins to the Fungal Cell Surface  

PubMed Central

Additional genes in the growing ALS family of Candida albicans were isolated by PCR screening of a genomic fosmid library with primers designed from the consensus tandem-repeat sequence of ALS1. This procedure yielded fosmids encoding ALS2 and ALS4. ALS2 and ALS4 conformed to the three-domain structure of ALS genes, which consists of a central domain of tandemly repeated copies of a 108-bp motif, an upstream domain of highly conserved sequences, and a domain of divergent sequences 3? of the tandem repeats. Alignment of five predicted Als protein sequences indicated conservation of N- and C-terminal hydrophobic regions which have the hallmarks of secretory signal sequences and glycosylphosphatidylinositol addition sites, respectively. Heterologous expression of an N-terminal fragment of Als1p in Saccharomyces cerevisiae demonstrated function of the putative signal sequence with cleavage following Ala17. This signal sequence cleavage site was conserved in the four other Als proteins analyzed, suggesting identical processing of each protein. Primary-structure features of the five Als proteins suggested a cell-surface localization, which was confirmed by indirect immunofluorescence with an anti-Als antiserum. Staining was observed on mother yeasts and germ tubes, although the intensity of staining on the mother yeast decreased with elongation of the germ tube. Similar to other ALS genes, ALS2 and ALS4 were differentially regulated. ALS4 expression was correlated with the growth phase of the culture; ALS2 expression was not observed under many different in vitro growth conditions. The data presented here demonstrate that ALS genes encode cell-surface proteins and support the conclusion that the size and number of Als proteins on the C. albicans cell surface vary with strain and growth conditions. PMID:9765564

Hoyer, L. L.; Payne, T. L.; Hecht, J. E.

1998-01-01

322

AnnuAl report JAhresbericht  

E-print Network

AnnuAl report JAhresbericht rApport d'Activités 2011 #12;1LE MOT DU RECTEUR Le mot du RecteuR Le'Université puisqu'il y existe une diversité de perspectives par rapport aux personnes ou aux structures devant for Systems Biomedicine moved into its new building in Belval. Belval is slowly becoming the fourth campus

van der Torre, Leon

323

Nucleants of Eutectic Silicon in Al-Si Hypoeutectic Alloys: ?-(Al, Fe, Si) or AlP Phase  

NASA Astrophysics Data System (ADS)

A thermodynamic description of the Al-Si-P-Fe quaternary system focused on Al-(Si)-rich alloys is developed. The solidification sequence in typical Al-7Si cast alloys is derived using thermodynamic calculations of the phase diagrams and solidification simulation under Scheil and constrained Scheil conditions. The previously claimed nucleation of eutectic silicon by ?-(Al,Fe,Si) particles is not possible because under all conditions, ?-(Al,Fe,Si) precipitates after (Si) in pertinent alloys. Variation of P in the ppm range is crucial because it changes the solidification sequence of AlP and (Si).

Liang, Song-Mao; Schmid-Fetzer, Rainer

2014-11-01

324

Dynamic nanomechanical properties of novel Si-rich intermetallic coatings growth on a medical 316 LVM steel by hot dipping in a hypereutectic Al-25Si alloy.  

PubMed

This aim of this study is to determine the elastoplastic properties of Ni-free Al3FeSi2 intermetallic coatings grown on medical stainless steel under different experimental conditions. Elastoplastic properties are defined by the plasticity index (PI), which correlates the hardness and the Young?s modulus. Special emphasis is devoted to correlate the PI with the wear resistance under sliding contact, determined by scratch testing, and fracture toughness, determined by using a novel method based on successive impacts with small loads. With regard to the substrate, the developed coatings are harder and exhibit a lower Young?s reduced modulus, irrespective of the experimental conditions. It has been shown that preheating of the samples prior to hot dipping and immersion influences the type and volume fraction of precipitates, which in turn also affect the nanomechanical properties. The higher the preheating temperature is, the greater the Young?s reduced modulus is. For a given preheating condition, an increase of the immersion time yields a decrease in hardness. Although apparent friction coefficients of coated specimens are smaller than those obtained on AISI 316 LVM, they increase when using preheating or higher immersion times during processing, which correlates with the PI. The presence of precipitates produces an increase in fracture toughness, with values greater than those presented by samples processed on melted AlSi alloys with lower Si content (12wt%). Therefore, these intermetallic coatings could be considered "hard but tough", suitable to enhance the wear resistance, especially when using short periods of immersion. PMID:25778350

Frutos, E; González-Carrasco, J L

2015-06-01

325

The Collections - Dar al-Athar al-Islamiyyah  

NSDL National Science Digital Library

Regarded by experts as one of a handful of the most comprehensive collections of Islamic art in the world, the al-Sabah holdings in Kuwait feature 20,000 objects from geographically and chronologically diverse locations. Nine categories - Metals, Ceramics, Glass, Ivory & Wood, Jewelry & Hardstone, Numismatics, Rugs & Textiles, Manuscripts & Calligraphy, and Stone & Stucco - can be accessed from the collections page with the click of a mouse. Within each category, short essays contextualize the beautiful photographs of ancient, medieval, and modern Islamic art in a wide variety of mediums and styles.

326

Thermal expansion of gehlenite, Ca 2 Al[AlSiO 7 ], and the related aluminates Ln CaAl[Al 2 O 7 ] with Ln =Tb, Sm  

Microsoft Academic Search

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1,100 K) and SmCaAl[Al2O7] (up to T=1,024 K) has been determined. All compounds are of the melilite structure type with space group\\u000a $$P\\\\bar {4}2_1\\\\,m.$$ Thermal expansion data was obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The

L. Peters; K. Knorr; M. Knapp; W. Depmeier

2005-01-01

327

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln = Tb, Sm  

Microsoft Academic Search

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1100 K) and SmCaAl[Al2O7] (up to T=1024 K) has been determined. All compounds are of the melilite structure type with space group P{bar{4}}21m. Thermal expansion data were obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg

L. Peters; K. Knorr; M. Knapp; W. Depmeier

2005-01-01

328

Thermal expansion of gehlenite, Ca 2 Al[AlSiO 7 ], and the related aluminates Ln CaAl[Al 2 O 7 ] with Ln = Tb, Sm  

Microsoft Academic Search

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1100 K) and SmCaAl[Al2O7] (up to T=1024 K) has been determined. All compounds are of the melilite structure type with space group\\u000a $$P{\\\\bar{4}}2_{1}m.$$ Thermal expansion data were obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches\\u000a Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal

L. Peters; K. Knorr; M. Knapp; W. Depmeier

2005-01-01

329

NiAl-base composite containing high volume fraction of AlN for advanced engines  

NASA Technical Reports Server (NTRS)

A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 to 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAlY, and FeAl.

Hebsur, Mohan (inventor); Whittenbeger, John D. (inventor); Lowell, Carl F. (inventor)

1994-01-01

330

Contribution of interface capacitance to the electric-field breakdown in thin-film AlAlOx Al capacitors  

E-print Network

) of the true breakdown electric field Eb across the dielectric. By modeling this interface contribution the dielectric, this cor- responds to a surface charge density on the aluminum elec- trodes at breakdown givenContribution of interface capacitance to the electric-field breakdown in thin-film Al­AlOx ­Al

Hebard, Arthur F.

331

Isolde Lasoen ALS ontsnapt aan uitsluiting  

E-print Network

gezet kooitje kan gepord worden tot vermaak van het volk. Een Guantanamo Bay voor huisdieren, zeg maar, al hoef je voor een verblijf in Guantanamo geen 6 of 8 euro te beta- len, gewoon hoesten als een

332

(12) United States Patent Vertes et al.  

E-print Network

(12) United States Patent Vertes et al. (54) LASER DESORPTION IONIZATION AND PEPTIDE SEQUENCING. (21) Appl. No.: 11/674,671 (22) Filed: Feb. 14,2007 (65) Prior Publication Data US 2009/0321626 Al Dec Suizdak et al. 6,589,485 B2 7/2003 Koster 6,794,196 B2 912004 Fonash et al. 6,846,681 B2 112005 Buriak et

Vertes, Akos

333

(12) United States Patent Vertes et al.  

E-print Network

(12) United States Patent Vertes et al. (54) THREE-DIMENSIONAL MOLECULAR IMAGING BY INFRARED LASER/0012831 Al Jan. 21, 2010 Related U.S. Application Data (63) Continuation-in-part of application No. 121176,656,690 B2 6,744,046 B2 6,991,903 B2 7,084,396 B2 12/2003 Crooke et al. 612004 Valaskovic et al. 112006 Fu

Vertes, Akos

334

(12) United States Patent Fallon et al.  

E-print Network

(12) United States Patent Fallon et al. (54) SYSTEM AND METHOD FOR DATA FEED ACCELERATION/131,631 (22) Filed: Jun. 2,2008 (65) Prior Publication Data US 200910287839 Al Nov. 19,2009 Related U References Cited U.S. PATENT DOCUMENTS 3,394,352 A 7/1968 Wernikoff et al. 3,490,690 A 111970 Apple et al. 4

Shamos, Michael I.

335

(12) United States Patent Reardan et al.  

E-print Network

(12) United States Patent Reardan et al. (54) SENSITIVE DRUG DISTRIBUTION SYSTEM AND METHOD (75 US 2005/0090425 Al Apr. 28, 2005 Related U.S. Application Data Division of application No.1 0,847,764 A 711989 Halvorson 4,976,351 A 1211990 Mangini et al. 5,737,539 A 411998 Edelson et al. 5,845,255 A 1211998

Shamos, Michael I.

336

Aluminium distribution in ZSM-5 revisited: The role of Al-Al interactions  

SciTech Connect

We present a theoretical study of the distribution of Al atoms in zeolite ZSM-5 with Si/Al=47, where we focus on the role of Al-Al interactions rather than on the energetics of Al/Si substitutions at individual sites. Using interatomic potential methods, we evaluate the energies of the full set of symmetrically independent configurations of Al siting in a Si{sub 94}Al{sub 2}O{sub 192} cell. The equilibrium Al distribution is determined by the interplay of two factors: the energetics of the Al/Si substitution at an individual site, which tends to populate particular T sites (e.g., the T14 site), and the Al-Al interaction, which at this Si/Al maximises Al-Al distances in general agreement with Dempsey's rule. However, it is found that the interaction energy changes approximately as the inverse of the square of the distance between the two Al atoms, rather than the inverse of the distance expected if this were merely charge repulsion. Moreover, we find that the anisotropic nature of the framework density plays an important role in determining the magnitude of the interactions, which are not simply dependent on Al-Al distances. - Graphical abstract: Role of Al-Al interactions in high silica ZSM-5 is shown to be anisotropic in nature and not dependent solely on Coulombic interactions. Highlights: Black-Right-Pointing-Pointer Si-Al distribution in ZSM-5 is revisited, stressing the role of the Al-Al interaction. Black-Right-Pointing-Pointer Coulomb interactions are not the key factors controlling the Al siting. Black-Right-Pointing-Pointer Anisotropy of the framework is identified as a source of departure from Dempsey's rule.

Ruiz-Salvador, A. Rabdel, E-mail: rabdel@imre.oc.uh.cu [Group of Materials Developed by Design, Division of Chemistry and Technology of Materials, Institute of Materials Science and Engineering (IMRE), University of Havana, Havana 10400 (Cuba); Grau-Crespo, Ricardo; Gray, Aileen E.; Lewis, Dewi W. [Department of Chemistry, University College London, 20 Gordon Street, London, WC1H OAJ (United Kingdom)] [Department of Chemistry, University College London, 20 Gordon Street, London, WC1H OAJ (United Kingdom)

2013-02-15

337

Effect of Al-Si-Al and Al-Si-Si-Al Pairs in the ZSM-5 Zeolite Framework on the 27 NMR Spectra. A Combined High-Resolution 27  

E-print Network

Effect of Al-Si-Al and Al-Si-Si-Al Pairs in the ZSM-5 Zeolite Framework on the 27 Al NMR Spectra. A Combined High-Resolution 27 Al NMR and DFT/MM Study Jiri´ Dedecek, Stepan Sklenak,*, Chengbin Li, Blanka of the presence of Al-O-Si-O-Al and Al-O-Si-O-Si-O-Al sequences in the ZSM-5 zeolite framework on the local

Sklenak, Stepan

338

United States Patent [19] Church et al.  

E-print Network

United States Patent [19] Church et al. [54] CHARACTERIZATION OF INDIVIDUAL POLYMER MOLECULES BASED al.. "ANeutral Amino Acid Change in Segment TIS4 Dramatically Alters the Gating Properties of the Volt- age-Dependent Sodium Channel". 1990, Proc. Natl. Acad. Sci. USA, 87:323-27. Bensirnon. A.. et al

Church, George M.

339

(12) United States Patent Likourezos et al.  

E-print Network

(12) United States Patent Likourezos et al. (54) SYSTEM AND METHOD FOR EFFECTING A REAL: Nov. 14, 2001 (65) Prior Publication Data US 2002/0095377 Al Jul. 18, 2002 Related U.S. Application Cited U.S. PATENT DOCUMENTS 4,799,156 A 4,876,648 A 111989 Shavit et al. 1011989 Lloyd 102 102 111111

Shamos, Michael I.

340

Klimes et al. 1997 Dioscorea japonica  

E-print Network

and Silvertown 2004 Charpentier et al. 2000 Eckert 2000 Maynard Smith 1980 Utricularia australis f. tenuicaulis U. macrorhiza U. australis F1 Kameyama et al. 2005 Kameyama and Ohara 2006 3 genet #12;262 Barrett et al. 1993, Ohara M (2005) Hybrid origins and F1 dominance in the free-floating, sterile bladderwort, Utricularia

Tomimatsu,, Hiroshi

341

Wear behavior of Al-Al{sub 3}Ti composite manufactured by a centrifugal method  

SciTech Connect

The purpose of the present study was to develop a wear-resistant, light Al-Al{sub 3}Ti composite material. An Al-Al{sub 3}Ti composite specimen was machined from a thick-walled tube of Al-Al{sub 3}Ti functionally graded material (FGM) manufactured by the centrifugal method from a commercial ingot of Al-5 mass% Ti master alloy. The alloy was heated to a temperature where solid Al{sub 3}Ti particles resided in a liquid Al matrix, and then the centrifugal method was carried out. Al{sub 3}Ti particles in a commercial alloy ingot exist as platelets, and this shape was maintained through the casting. Three kinds of wear specimens were prepared, taking into account the morphology of the Al{sub 3}Ti particles in the thick-walled FGM tube; the Al{sub 3}Ti particles were arranged with their platelet planes nearly normal to the radial direction as a result of the applied centrifugal force. The wear resistance of the Al-Al{sub 3}Ti composite was significantly higher than that of pure Al. Wear-resistance anisotropy and dissolution of the Al{sub 3}Ti into the Al matrix at the near-surface region, around 100 {micro}m in depth, were also observed. The mechanism of the supersaturated-layer formation and the origin of the anisotropic wear resistance are discussed.

Watanabe, Yoshimi; Yamanaka, Noboru; Fukui, Yasuyoshi

1999-12-01

342

Systems Engineering Techniques for ALS Decision Making  

NASA Technical Reports Server (NTRS)

The Advanced Life Support (ALS) Metric is the predominant tool for predicting the cost of ALS systems. Metric goals for the ALS Program are daunting, requiring a threefold increase in the ALS Metric by 2010. Confounding the problem, the rate new ALS technologies reach the maturity required for consideration in the ALS Metric and the rate at which new configurations are developed is slow, limiting the search space and potentially giving the perspective of a ALS technology, the ALS Metric may remain elusive. This paper is a sequel to a paper published in the proceedings of the 2003 ICES conference entitled, "Managing to the metric: an approach to optimizing life support costs." The conclusions of that paper state that the largest contributors to the ALS Metric should be targeted by ALS researchers and management for maximum metric reductions. Certainly, these areas potentially offer large potential benefits to future ALS missions; however, the ALS Metric is not the only decision-making tool available to the community. To facilitate decision-making within the ALS community a combination of metrics should be utilized, such as the Equivalent System Mass (ESM)-based ALS metric, but also those available through techniques such as life cycle costing and faithful consideration of the sensitivity of the assumed models and data. Often a lack of data is cited as the reason why these techniques are not considered for utilization. An existing database development effort within the ALS community, known as OPIS, may provide the opportunity to collect the necessary information to enable the proposed systems analyses. A review of these additional analysis techniques is provided, focusing on the data necessary to enable these. The discussion is concluded by proposing how the data may be utilized by analysts in the future.

Rodriquez, Luis F.; Drysdale, Alan E.; Jones, Harry; Levri, Julie A.

2004-01-01

343

Opportunity's 'Rub al Khali' Panorama  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for Opportunity's 'Rub al Khali' Panorama (QTVR)

This panoramic image, dubbed 'Rub al Khali,' was acquired by NASA's Mars Exploration Rover Opportunity on the plains of Meridiani during the period from the rover's 456th to 464th sols on Mars (May 6 to May 14, 2005). Opportunity was about 2 kilometers (1.2 miles) south of 'Endurance Crater' at a place known informally as 'Purgatory Dune.'

The rover was stuck in the dune's deep fine sand for more than a month. 'Rub al Khali' (Arabic translation: 'the empty quarter') was chosen as the name for this panorama because it is the name of a similarly barren, desolate part of the Saudi Arabian desert on Earth.

The view spans 360 degrees. It consists of images obtained in 97 individual pointings of the panoramic camera. The camera took images with five camera filters at each pointing. This 22,780-by-6,000-pixel mosaic is an approximately true-color rendering generated using the images acquired through filters admitting light wavelengths of 750, 530, and 480 nanometers.

Lighting varied during the nine sols it took to acquire this panorama, resulting in some small image seams within the mosaic. These seams have been smoothed in sky parts of the mosaic to better simulate the vista that a person would see if able to view it all at the same time on Mars.

Opportunity's tracks leading back to the north (center of the panorama) are a reminder of the rover's long trek from Endurance Crater. The deep ruts dug by Opportunity's wheels as it became stuck in the sand appear in the foreground. The crest and trough of the last ripple the rover crossed before getting stuck is visible in the center. These wind-formed sand features are only about 10 to 15 centimeters (4 to 6 inches) tall. The crest of the actual ripple where the rover got stuck can be seen just to the right of center. The tracks and a few other places on and near ripple crests can be seen in this color image to be dustier than the undisturbed or 'normal' plains soils in Meridiani. Since the time these ruts were made, some of the dust there has been blown away by the wind, reaffirming the dynamic nature of the martian environment, even in this barren, ocean-like desert of sand.

2005-01-01

344

A nuclear magnetic resonance probe of Fe-Al and Al20V2Eu intermetallics  

E-print Network

. To study the variety of magnetic properties, we use NMR, magnetic susceptibility, specific heat and other methods in this work. The microscopic electronic and magnetic properties of the Al-rich Fe-Al system and Al20V2Eu have been studied via 27Al NMR...

Chi, Ji

2009-05-15

345

Reactive Plasma Spraying of Fine Al2O3/AlN Feedstock Powder  

NASA Astrophysics Data System (ADS)

Reactive plasma spraying (RPS) is a promising technology for in situ formation of aluminum nitride (AlN) coatings. Recently, AlN-based coatings were fabricated by RPS of alumina (Al2O3) powder in N2/H2 thermal plasma. This study investigated the feasibility of RPS of a fine Al2O3/AlN mixture and the influence of the plasma gases (N2, H2) on the nitriding conversion, and coating microstructure and properties. Thick AlN/Al2O3 coatings with high nitride content were successfully fabricated. The coatings consist of h-AlN, c-AlN, Al5O6N, ?-Al2O3, and a small amount of ?-Al2O3. Use of fine particles enhanced the nitriding conversion and the melting tendency by increasing the surface area. Furthermore, the AlN additive improved the AlN content in the coatings. Increasing the N2 gas flow rate improved the nitride content and complete crystal growth to the h-AlN phase, and enhanced the coating thickness. On the other hand, though the H2 gas is required for plasma nitriding of the Al2O3 particles, increasing its flow rate decreased the nitride content and the coating thickness. Remarkable influence of the plasma gases on the coating composition, microstructure, and properties was observed during RPS of the fine particles.

Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

2013-12-01

346

Comparative Genomic Discovery of miRNAs Grad et al.  

E-print Network

Comparative Genomic Discovery of miRNAs Grad et al. Computational and Experimental Identification throughout the adult life cycle (Feinbaum and Ambros, 1999; Lee et al., 1993; Reinhart et al., 2000 al., 1993; Wightman et al., 1993; Reinhart et al., 2000; Slack et al., 2000). Both lin-4 and let-7

Church, George M.

347

Single crystal growth and characterization of binary stoichiometric and Al-rich Ni 3Al  

Microsoft Academic Search

Binary stoichiometric Ni3Al (Ni–25at% Al) single crystals and Al-rich single-crystal-like (Ni–26at% Al, Ni–27at% Al) alloys that do not contain any ternary additions have been successfully grown for the first time, by using the floating zone method. The quality of the crystals was examined by the Laue X-ray back-reflection method and optical microscopy. The stoichiometric single crystals had good crystallinity. The

D. Golberg; M Demura; T Hirano

1998-01-01

348

Oxidation resistance of intermetallic compounds Al 3 Ti and TiAl  

Microsoft Academic Search

The oxidation kinetics and morphological features of Al3Ti and TiAl were investigated. The oxidation resistance of Al3Ti is much better than that of TiAl, for example, by a factor of about 30 at 1000° C for 48 h. The big difference in the oxidation resistance is related to the characteristics of the external oxide scales of a protective Al2O3 or

Y. Umakoshi; M. Yamaguchi; T. Sakagami; T. Yamane

1989-01-01

349

Cohesive, electronic and magnetic properties of the transition metal aluminides FeAl CoAl and NiAl  

Microsoft Academic Search

Electronic structure calculations using the tight-binding linear muffin tin orbital (TB-LMTO) method have been performed for three transition metal aluminides, viz. FeAl, CoAl and NiAl. The band structures and density of states (DOS), valence electron charge density contours and Fermi surfaces have been obtained and compared with the available experimental results as well as with existing theoretical calculations. The lattice

V. Sundararajan; B. R. Sahu; D. G. Kanhere; P. V. Panat; G. P. Das

1995-01-01

350

First-principles studies of typical long-period superstructures Al 5Ti 3, hAl 2Ti and r-Al 2Ti in Al-rich TiAl alloys  

Microsoft Academic Search

First-principles calculations are performed to study the structural stabilities, electronic and elastic properties of typical long-period superstructures Al5Ti3, h-Al2Ti and r-Al2Ti in Al-rich TiAl alloys together with ?-TiAl. The obtained lattice parameters by relaxation of crystalline cells are in good agreement with the experimental data. The calculated formation enthalpies show that r-Al2Ti has the highest structure stability from energetic point

Ping-Ying Tang; Bi-Yu Tang; Xu-Ping Su

2011-01-01

351

AISI Direct Steelmaking Program. Final technical report  

SciTech Connect

This final report deals with the results of a 5-yr project for developing a more energy-efficient, environmentally friendly, less costly process for producing hot metal than current coke ovens and blast furnaces. In the process, iron ore pellets are smelted in a foamy slag created by reaction of coal char with molten slag to produce CO. The CO further reacts with oxygen, which also reacts with coal volatile matter, to produce the heat necessary to sustain the endothermic reduction reaction. The uncombusted CO and H{sub 2} from the coal are used to preheat and prereduce hematite pellets for the most efficient use of the energy in the coal. Laboratory programs confirmed that the process steps worked. Pilot plant studies were successful. Economic analysis for a 1 million tpy plant is promising.

Aukrust, E.

1994-08-01

352

Reply to Vance et al.  

SciTech Connect

In our report of a family with a motor and sensory polyneuropathy that was linked to chromosome 3q, we classified this neuropathy as a form of hereditary motor and sensory neuropathy II (HMSN II, also known as {open_quotes}CMT2{close_quotes}). Doubts have been raised by Vance et al. as to whether this neuropathy should be classified as hereditary sensory autonomic neuropathy I (HSAN I) instead of HMSN II. While it is reasonable to raise such doubts, we believe that the neuropathy is best designated as HMSN II for the reasons described below. The group of disorders described as HSAN are characterized by primary or predominant involvement of sensory and autonomic neurons that fail to develop or that undergo atrophy and degeneration. These disorders were extensively reviewed by Dyck and Ohta, who initially described them as the hereditary sensory neuropathies (HSN). It was Dyck who subsequently suggested that these disorders be designated HSAN rather than HSN, because of the presence of autonomic involvement. 8 refs.

Woon-Chee Yee; Elliott, J.L; Kwon, J.M.; Goodfellow, P. [Washington Univ. School of Medicine, St. Louis, MO (United States)

1996-07-01

353

Crack-Free AlN/GaN Distributed Bragg Reflectors on AlN Templates  

NASA Astrophysics Data System (ADS)

We have demonstrated crack-free 30-pair-AlN/GaN distributed Bragg reflectors (DBRs) grown on AlN templates for the first time. A reasonably high reflectivity of 97.5% was obtained. X-ray diffraction measurements revealed that the AlN templates cause compressive stress in DBRs. At the same time, the AlN/GaN DBRs were found to relax to average AlGaN alloys with AlN mole fractions determined by the thickness ratio of the AlN layer to one pair of AlN and GaN in DBRs regardless of the underlying template, AlN or GaN.

Yagi, Kouta; Kaga, Mitsuru; Yamashita, Kouji; Takeda, Kenichirou; Iwaya, Motoaki; Takeuchi, Tetsuya; Kamiyama, Satoshi; Amano, Hiroshi; Akasaki, Isamu

2012-05-01

354

Charging effect of Al{sub 2}O{sub 3} thin films containing Al nanocrystals  

SciTech Connect

In this work, Al{sub 2}O{sub 3} thin film containing Al nanocrystals (nc-Al) is deposited on Si substrate by radio frequency sputtering to form a metal-insulator-semiconductor structure. Both electron and hole trapping in nc-Al are observed. The charge storage ability of the nc-Al/Al{sub 2}O{sub 3} thin films provides the possibility of memory applications. Charging in the nc-Al also leads to a change in the dc resistance of the thin films, namely, the electron trapping in the nc-Al leads to an increase in the resistance, whereas the resistance is reduced if there is hole trapping in the nc-Al.

Liu, Y. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054 (China); Chen, T. P.; Zhu, W.; Yang, M.; Cen, Z. H.; Wong, J. I. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Li, Y. B. [Center for Composite Materials, School of Astronautics, Harbin Institute of Technology, P.O. Box 3010, Harbin 150080 (China); Zhang, S. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Chen, X. B. [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054 (China); Fung, S. [Department of Physics, University of Hong Kong (Hong Kong)

2008-10-06

355

Tensile Behavior of Al2o3/feal + B and Al2o3/fecraly Composites  

NASA Technical Reports Server (NTRS)

The feasibility of Al2O3/FeAl + B and Al2O3/FeCrAlY composites for high-temperature applications was assessed. The major emphasis was on tensile behavior of both the monolithics and composites from 298 to 1100 K. However, the study also included determining the chemical compatibility of the composites, measuring the interfacial shear strengths, and investigating the effect of processing on the strength of the single-crystal Al2O3 fibers. The interfacial shear strengths were low for Al203/FeAl + B and moderate to high for Al203/FeCrAlY. The difference in interfacial bond strengths between the two systems affected the tensile behavior of the composites. The strength of the Al203 fiber was significantly degraded after composite processing for both composite systems and resulted in poor composite tensile properties. The ultimate tensile strength (UTS) values of the composites could generally be predicted with either rule of mixtures (ROM) calculations or existing models when using the strength of the etched-out fiber. The Al2O3/FeAl + B composite system was determined to be unfeasible due to poor interfacial shear strengths and a large mismatch in coefficient of thermal expansion (CTE). Development of the Al2O3/FeCrAlY system would require an effective diffusion barrier to minimize the fiber strength degradation during processing and elevated temperature service.

Draper, S. L.; Eldridge, J. I.; Aiken, B. J. M.

1995-01-01

356

Teatro al Sur y la escena Argentina  

E-print Network

140 LATIN AMERICAN THEATRE REVIEW Teatro al Sur y la escena Argentina Acaba de aparecer un nuevo número de Teatro al Sur, Revista Latinoamericana. Su título de tapa - Teatro Argentino a varias voces - resume la intención de esta nueva entrega... publicación: nos pareció oportuno apelar al testimonio directo de algunos de nuestros creadores y a través de sus voces - con particulares texturas y coloraturas - ir configurando un fragmento significativo del presente de nuestra escena. Hemos preferido...

2000-04-01

357

Mangan-Nickel-und Cobaltverbindungen als Konversionselektrodenmaterialien  

E-print Network

Mangan- Nickel- und Cobaltverbindungen als Konversionselektrodenmaterialien für Lithium ____________________________________________________63 5.1 SYNTHESE UND CHARAKTERISIERUNG VON NANOSKALIGEM LIF ______________________________63 5

Hoffmann, Rolf

358

Superbend era begins swiftly at the ALS  

SciTech Connect

The successful installation and commissioning of high-field superconducting bend magnets (superbends) in three curved sectors of ALS storage ring was the first time the magnet lattice of an operating synchrotron light source has been retrofitted in this fundamental way. As a result, the ALS now offers an expanded spectral range well into the hard x-ray region without compromising either the number of undulators or their high brightness in the soft x-ray region for which the ALS design was originally optimized. In sum, when the superbend-enhanced ALS started up for user operations in October 2001, it marked the beginning of a new era in its history.

Robinson, Art; Tamura, Lori

2001-11-29

359

Microstructures and wear resistances of hybrid Al–(Al 3Ti+Al 3Ni) FGMs fabricated by a centrifugal method  

Microsoft Academic Search

The Al based functionally graded materials (FGMs), reinforced by a hybrid of Al3Ti platelets and Al3Ni granular particles, were fabricated by the centrifugal method with both ingots of commercial Al–5mass%Ti and Al–20mass%Ni master alloys. The ratios of Al–Ti and Al–Ni alloys were 3:1, 1:1 and 1:3 (in mass), and the applied G numbers are 30, 50 and 80. The microstructures

Yoshimi Watanabe; Tatsuru Nakamura

2001-01-01

360

Toxicity of Al to Desulfovibrio desulfuricans  

PubMed Central

The toxicity of Al to Desulfovibrio desulfuricans G20 was assessed over a period of 8 weeks in a modified lactate C medium buffered at four initial pHs (5.0, 6.5, 7.2, and 8.3) and treated with five levels of added Al (0, 0.01, 0.1, 1.0, and 10 mM). At pH 5, cell population densities decreased significantly and any effect of Al was negligible compared to that of the pH. At pHs 6.5 and 7.2, the cell population densities increased by 30-fold during the first few days and then remained stable for soluble-Al concentrations of <5 × 10?5 M. In treatments having total-Al concentrations of ?1 mM, soluble-Al concentrations exceeded 5 × 10?5 M and limited cell population growth substantially and proportionally. At pH 8.3, soluble-Al concentrations were below the 5 × 10?5 M toxicity threshold and cell population density increases of 20- to 40-fold were observed. An apparent cell population response to added Al at pH 8.3 was attributed to the presence of large, spirilloidal bacteria (accounting for as much as 80% of the cells at the 10 mM added Al level). Calculations of soluble-Al speciation for the pH 6.5 and 7.2 treatments that showed Al toxicity suggested the possible presence of the Al13O4(OH)24(H2O)127+ “tridecamer” cation and an inverse correlation of the tridecamer concentration and the cell population density. Analysis by 27Al nuclear magnetic resonance spectroscopy, however, yielded no evidence of this species in freshly prepared samples or those taken 800 days after inoculation. Exclusion of the tridecamer species from the aqueous speciation calculations at pHs 6.5 and 7.2 yielded inverse correlations of the neutral Al(OH)3 and anionic Al(OH)4? monomeric species with cell population density, suggesting that one or both of these ions bear primary responsibility for the toxicity observed. PMID:12839782

Amonette, J. E.; Russell, C. K.; Carosino, K. A.; Robinson, N. L.; Ho, J. T.

2003-01-01

361

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln = Tb, Sm  

NASA Astrophysics Data System (ADS)

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1100 K) and SmCaAl[Al2O7] (up to T=1024 K) has been determined. All compounds are of the melilite structure type with space group P{bar{4}}21m. Thermal expansion data were obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal expansion coefficients for gehlenite were found to be: ?1=7.2(4)×10-6×K-1+3.6(7)×10-9? T×K-2 and ?3=15.0(1)×10-6×K-1. For TbCaAl[Al2O7] the respective values are: ?1=7.0(2)×10-6×K-1+2.0(2)×10-9? T×K-2 and ?3=8.5(2)×10-6×K-1+2.0(3)×10-9? T×K-2, and the thermal expansion coefficients for SmCaAl[Al2O7] are: ?1=6.9(2)×10-6×K-1+1.7(2)×10-9? T×K-2 and ?3=9.344(5)×10-6×K-1. The expansion mechanisms of the three compounds are explained in terms of structural trends obtained from Rietveld refinements of the crystal structures of the compounds against the powder diffraction patterns. No structural phase transitions have been observed. While gehlenite behaves like a ‘proper’ layer structure, the aluminates show increased framework structure behavior. This is most probably explained by stronger coulombic interactions between the tetrahedral conformation and the layer-bridging cations due to the coupled substitution (Ca2++Si4+) ( Ln 3++Al3+) in the melilite-type structure.

Peters, L.; Knorr, K.; Knapp, M.; Depmeier, W.

2005-12-01

362

Preparation and Thermoelectric Properties of YbAl3 Thermoelectric Materials with Excessive Al  

NASA Astrophysics Data System (ADS)

A method to prepare YbAl3 sample with an accurate stoichiometric ratio has been developed by a melting, quenching, annealing and spark plasma sintering (SPS) method. A series of YbAl3 thermoelectric materials with nominal compositions YbAl3+x (x = 0-0.3, ?x = 0.1) have been prepared using the method. We have explored the effects of the excessive Al on phase compositions, microstructure and transport properties. The quenched samples are composed of YbAl3, YbAl2, Yb, and Al. All the annealed samples are composed of main phase YbAl3 and a trace of Al; some annealed samples with x = 0 and x = 0.1 still contain a trace of YbAl2. The SPSed samples with x ? 0.1 are composed of single-phase YbAl3, though a trace of YbAl2 still occured in the SPSed sample with x = 0. The electrical conductivity, Seebeck coefficient, power factor, thermal conductivity and ZT values are first increased with increasing x in the range of 0-0.2 and then decreased when x > 0.2. These thermoelectric properties evolutions originate from the change of densities and chemical composition induced by the excessive Al. The highest ZT value reaches 0.28 at 300 K for the SPSed sample with x = 0.2.

He, Dan-qi; Zhao, Wen-Yu; Mu, Xin; Zhou, Hong-yu; Zhang, Qing-jie

2015-01-01

363

SCIENCE CAREER Al nanoclusters in coagulants and granulates: application  

E-print Network

aluminum hydroxide complexes with 1 nm diameter and 1­2 nm length. Al13 is a cluster of four Al trimers suitable for arsenic removal. The aluminum nanocl- usters Al13 (AlO4Al12(OH)24H2O12 7? ) and Al30 (Al2O8Al properties of aluminum nanoclusters and their efficiency for water treatment, particularly for arsenic

Wehrli, Bernhard

364

Al Shabaab's Foreign Threat to Somalia  

Microsoft Academic Search

This article focuses on the threat to Somalia by al Shabaab (The Youth), an extremist organization that controls most of southern and central Somalia. It learned its strategy and tactics from al Qaeda and the Taliban and relies heavily on a relatively small number of foreign fighters, most of whom are Somalis with foreign passports from the large Somali diaspora.

David Shinn

2011-01-01

365

Freund et al. Mechanisms underlying differential expression  

E-print Network

Freund et al. - 1 - Mechanisms underlying differential expression of interleukin-8 in breast cancer cells Ariane Freund, Valérie Jolivel, Sébastien Durand, Nathalie Kersual, Dany Chalbos, Carine Chavey #12;Freund et al. - 2 - ABSTRACT We have recently reported that Interleukin-8 (IL-8) expression

Boyer, Edmond

366

Quantitatively Probing the Al Distribution in Zeolites  

SciTech Connect

The degree of substitution of Si4+ by Al3+ in the oxygen-terminated tetrahedra (Al T-sites) of zeolites determines the concentration of ion-exchange and Brønsted acid sites. As the location of the tetrahedra and the associated subtle variations in bond angles influence the acid strength, quantitative information about Al T-sites in the framework is critical to rationalize catalytic properties and to design new catalysts. A quantitative analysis is reported that uses a combination of extended X-ray absorption fine structure (EXAFS) analysis and 27Al MAS NMR spectroscopy supported by DFT-based molecular dynamics simulations. To discriminate individual Al atoms, sets of ab initio EXAFS spectra for various T-sites are generated from DFT-based molecular dynamics simulations allowing quantitative treatment of the EXAFS single- and multiple-photoelectron scattering processes out to 3-4 atom shells surrounding the Al absorption center. It is observed that identical zeolite types show dramatically different Al-distributions. A preference of Al for T-sites that are part of one or more 4-member rings in the framework over those T-sites that are part of only 5- and 6-member rings in the HBEA150 sample has been determined from a combination of these methods. This work was supported by the U. S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences.

Vjunov, Aleksei; Fulton, John L.; Huthwelker, Thomas; Pin, Sonia; Mei, Donghai; Schenter, Gregory K.; Govind, Niranjan; Camaioni, Donald M.; Hu, Jian Z.; Lercher, Johannes A.

2014-06-11

367

76 FR 35938 - The Designation of Othman al-Ghamdi Also Known as Al Umairah al-Ghamdi, Also Known as Uthman al...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Known as Uthman Ahmad Uthman al-Ghamdi, Also Known as Othman Ahmed Othman al-Omirah as a Specially Designated Global Terrorist Pursuant to Section 1(b) of Executive Order 13224, as Amended Acting under the authority of and in accordance with...

2011-06-20

368

Diana Al-Hadid: Identity and Heritage  

ERIC Educational Resources Information Center

Diana Al-Hadid's sculptures reflect the many locations, cultures, histories, and mythologies that have shaped her as an artist. In large-scale works which have the appearance of architectural ruins, Al-Hadid employs imagery drawn from many diverse interests including science and technology, history, and literature. She also incorporates images and…

Jungerberg, Tom; Smith, Anna; Borsh, Colleen

2012-01-01

369

PROVE DI IMPATTO SU PANNELLI AL - NOMEX  

Microsoft Academic Search

Sommario Il presente lavoro descrive prove preliminari di impatto a bassa velocità effettuate su un pannello sandwich (Al-Nomex) utilizzato estesamente su fusoliere di elicottero. Non essendoci una normativa vigente sull'intero processo di prova, è stato eseguito un ampio studio preliminare al fine di valutare le possibili soluzioni utilizzabili. E' stata quindi realizzata una struttura di prova dedicata composta da una

M. Giglio; A. Manes

370

Durability Assessment of TiAl Alloys  

NASA Technical Reports Server (NTRS)

The durability of TiAl is a prime concern for the implementation of TiAl into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content TiAl alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content TiAl alloy (Ti-45Al-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48Al-2Cr- 2Nb, Ti-47Al-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45Al-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.

Draper, Susan L.; Lerch, Bradley A.

2008-01-01

371

Energetics of Al13 Keggin cluster compounds  

PubMed Central

The ?-Al13 Keggin aluminum hydroxide clusters are essential models in establishing molecular pathways for geochemical reactions. Enthalpies of formation are reported for two salts of aluminum centered ?-Keggin clusters, Al13 selenate, (Na(AlO4)Al12(OH)24(SeO4)4•12H2O) and Al13 sulfate, (NaAlO4Al12(OH)24(SO4)4•12H2O). The measured enthalpies of solution, ?Hsol, at 28?°C in 5 N HCl for the ?-Al13 selenate and sulfate are ?924.57 (± 3.83) and ?944.30 ( ± 5.66) kJ·mol-1, respectively. The enthalpies of formation from the elements, ?Hf,el, for Al13 selenate and sulfate are ?19,656.35 ( ± 67.30) kJ·mol-1, and ?20,892.39 ( ± 70.01) kJ·mol-1, respectively. In addition, ?Hf,el for sodium selenate decahydrate was calculated using data from high temperature oxide melt solution calorimetry measurements: ?4,006.39 ( ± 11.91) kJ·mol-1. The formation of both ?-Al13 Keggin cluster compounds is exothermic from oxide-based components but energetically unfavorable with respect to a gibbsite-based assemblage. To understand the relative affinity of the ?-Keggin clusters for selenate and sulfate, the enthalpy associated with two S-Se exchange reactions was calculated. In the solid state, selenium is favored in the Al13 compound relative to the binary chalcogenate, while in 5 N HCl, sulfur is energetically favored in the cluster compound compared to the aqueous solution. This contribution represents the first thermodynamic study of ?-Al13 cluster compounds and establishes a method for other such molecules, including the substituted versions that have been created for kinetic studies. Underscoring the importance of ?-Al13 clusters in natural and anthropogenic systems, these data provide conclusive thermodynamic evidence that the Al13 Keggin cluster is a crucial intermediate species in the formation pathway from aqueous aluminum monomers to aluminum hydroxide precipitates. PMID:21852572

Armstrong, Christopher R.; Casey, William H.; Navrotsky, Alexandra

2011-01-01

372

NiAl alloys for structural uses  

NASA Technical Reports Server (NTRS)

Alloys based on the intermetallic compound NiAl are of technological interest as high temperature structural alloys. These alloys possess a relatively low density, high melting temperature, good thermal conductivity, and (usually) good oxidation resistance. However, NiAl and NiAl-base alloys suffer from poor fracture resistance at low temperatures as well as inadequate creep strength at elevated temperatures. This research program explored macroalloying additions to NiAl-base alloys in order to identify possible alloying and processing routes which promote both low temperature fracture toughness and high temperature strength. Initial results from the study examined the additions of Fe, Co, and Hf on the microstructure, deformation, and fracture resistance of NiAl-based alloys. Of significance were the observations that the presence of the gamma-prime phase, based on Ni3Al, could enhance the fracture resistance if the gamma-prime were present as a continuous grain boundary film or 'necklace'; and the Ni-35Al-20Fe alloy was ductile in ribbon form despite a microstructure consisting solely of the B2 beta phase based on NiAl. The ductility inherent in the Ni-35Al-20Fe alloy was explored further in subsequent studies. Those results confirm the presence of ductility in the Ni-35Al-20Fe alloy after rapid cooling from 750 - 1000 C. However exposure at 550 C caused embrittlement; this was associated with an age-hardening reaction caused by the formation of Fe-rich precipitates. In contrast, to the Ni-35Al-20Fe alloy, exploratory research indicated that compositions in the range of Ni-35Al-12Fe retain the ordered B2 structure of NiAl, are ductile, and do not age-harden or embrittle after thermal exposure. Thus, our recent efforts have focused on the behavior of the Ni-35Al-12Fe alloy. A second parallel effort initiated in this program was to use an alternate processing technique, mechanical alloying, to improve the properties of NiAl-alloys. Mechanical alloying in the conventional sense requires ductile powder particles which, through a cold welding and fracture process, can be dispersion strengthened by submicron-sized oxide particles. Using both the Ni-35Al-Fe alloys to contain approx. 1 v/o Y2O3. Preliminary results indicate that mechanically alloyed and extruded NiAl-Fe + Y2O3 alloys when heat treated to a grain-coarsened condition, exhibit improved creep resistance at 1000 C when compared to NiAl; oxidation resistance comparable to NiAl; and fracture toughness values a factor of three better than NiAl. As a result of the research initiated on this NASA program, a subsequent project with support from Inco Alloys International is underway.

Koss, D. A.

1991-01-01

373

Corrosion Studies of 2195 Al-Li Alloy and 2219 Al Alloy with Differing Surface Treatments  

NASA Technical Reports Server (NTRS)

Corrosion studies of 2195 Al-Li and 2219 Al alloys have been conducted using the scanning reference electrode technique (SRET) and the polarization resistance (PR) technique. The SRET was used to study corrosion mechanisms, while corrosion rate measurements were studied with the PR technique. Plates of Al203 blasted, soda blasted and conversion coated 2219 Al were coated with Deft primer and the corrosion rates studied with the EIS technique. Results from all of these studies are presented.

Danford, M. D.; Mendrek, M. J.

1998-01-01

374

High temperature creep behaviour of Al-rich Ti-Al alloys  

NASA Astrophysics Data System (ADS)

Compared to Ti-rich ?-TiAl-based alloys Al-rich Ti-Al alloys offer an additional reduction of in density and a better oxidation resistance which are both due to the increased Al content. Polycrystalline material was manufactured by centrifugal casting. Microstructural characterization was carried out employing light-optical, scanning and transmission electron microscopy and XRD analyses. The high temperature creep of two binary alloys, namely Al60Ti40 and Al62Ti38 was comparatively assessed with compression tests at constant true stress in a temperature range between 1173 and 1323 K in air. The alloys were tested in the cast condition (containing various amounts of the metastable phases Al5Ti3 and h-Al2Ti) and after annealing at 1223 K for 200 h which produced (thermodynamically stable) lamellar ?-TiAl + r-Al2Ti microstructures. In general, already the as-cast alloys exhibit a reasonable creep resistance at 1173 K. Compared with Al60Ti40, both, the as-cast and the annealed Al62Ti38 alloy exhibit better creep resistance up to 1323 K which can be rationalized by the reduced lamella spacing. The assessment of creep tests conducted at identical stress levels and varying temperatures yielded apparent activation energies for creep of Q = 430 kJ/mol for the annealed Al60Ti40 alloy and of Q = 383 kJ/mol for the annealed Al62Ti38 material. The latter coincides well with that of Al diffusion in ?-TiAl, whereas the former can be rationalized by the instability of the microstructure containing metastable phases.

Sturm, D.; Heilmaier, M.; Saage, H.; Aguilar, J.; Schmitz, G. J.; Drevermann, A.; Palm, M.; Stein, F.; Engberding, N.; Kelm, K.; Irsen, S.

2010-07-01

375

Dry sliding wear of Al alloy 2024Al 20 3 particle metal matrix composites  

Microsoft Academic Search

In the present investigation, Al 2024-15vol.%Al203 particulate (average size, 18 ?m) composites were fabricated using the liquid metallurgy route. The wear and friction characteristics of AI alloy 2024 and Al 2024-15vol.%Al203p composite in the as-extruded and peak-aged conditions were studied using a pin-on-disc machine (with a steel disc as the counterface material). The worn surfaces, subsurfaces and the debris were

Manish Narayan; M. K. Surappa; B. N. Pramila Bai

1995-01-01

376

Site preferences of indium impurity atoms in intermetallics having Al3Ti and Al3Zr crystal structures  

E-print Network

Site preferences of indium impurity atoms in intermetallics having Al3Ti and Al3Zr crystal · Indium was doped in samples of Al3V and Al3Ti (Al3Ti structure) and Al3Zr (Al3Zr structure) by arc-melting; doping at 10 ppb level. · Inequivalent Al-sites occupied by indium solutes were identified by measuring

Collins, Gary S.

377

Reassessment of Al-Ce and Al-Nd Binary Systems Supported by Critical Experiments and First-Principles  

E-print Network

Reassessment of Al-Ce and Al-Nd Binary Systems Supported by Critical Experiments and First The present study reinvestigates the Al-Ce and Al-Nd phase diagrams and reoptimizes their thermody- namics results and theoretical calculations show that Al2Nd (or Al2Ce) should be treated as a stoichiometric

Widom, Michael

378

Atomistic Modeling of RuAl and (RuNi) Al Alloys  

NASA Technical Reports Server (NTRS)

Atomistic modeling of RuAl and RuAlNi alloys, using the BFS (Bozzolo-Ferrante-Smith) method for alloys is performed. The lattice parameter and energy of formation of B2 RuAl as a function of stoichiometry and the lattice parameter of (Ru(sub 50-x)Ni(sub x)Al(sub 50)) alloys as a function of Ni concentration are computed. BFS based Monte Carlo simulations indicate that compositions close to Ru25Ni25Al50 are single phase with no obvious evidence of a miscibility gap and separation of the individual B2 phases.

Gargano, Pablo; Mosca, Hugo; Bozzolo, Guillermo; Noebe, Ronald D.; Gray, Hugh R. (Technical Monitor)

2002-01-01

379

High Al-content AlGaN\\/GaN MODFETs for ultrahigh performance  

Microsoft Academic Search

The use of an AlGaN layer with high Al mole-fraction is proposed to increase the equivalent figures of merit of the AlGaN\\/GaN MODFET structure. It is shown that the room temperature mobility has little degradation with increasing Al mole-fraction up to 50%. 0.7-?m gate-length Al0.5Ga0.5N\\/GaN MODFETs by optical lithography exhibit a current density of 1 A\\/mm and three-terminal breakdown voltages

Y.-F. Wu; B. P. Keller; P. Fini; S. Keller; T. J. Jenkins; L. T. Kehias; S. P. Denbaars; U. K. Mishra

1998-01-01

380

AlGaN/GaN/AlN quantum-well field-effect transistors with highly resistive AlN epilayers  

E-print Network

of the AlGaN/GaN/AlN QW-FET structure used in this study. A Si -doping level of 4.5 10AlGaN/GaN/AlN quantum-well field-effect transistors with highly resistive AlN epilayers Z. Y. Fana 66506-2601 Received 23 November 2005; accepted 5 January 2006; published online 16 February 2006 AlGaN/GaN

Jiang, Hongxing

381

Single-phase interdiffusion in the B2 type intermetallic compounds NiAl, CoAl and FeAl  

Microsoft Academic Search

Interdiffusion coefficients, D, in the B2 type NiAl, CoAl and FeAl phases have been determined by single phase diffusion couples over a wide temperature range from 1073 to 1773 K. The value of D in the NiAl and CoAl phases shows a minimum at about 47 at.% Al deviating slightly from the stoichiometric composition, while the value of D in

Ryusuke Nakamura; Koichi Takasawa; Yoshihiro Yamazaki; Yoshiaki Iijima

2002-01-01

382

Solar-blind ultraviolet AlInN/AlGaN distributed Bragg reflectors  

NASA Astrophysics Data System (ADS)

A 13.5-pair Al0.98In0.02N/Al0.77Ga0.23N distributed Bragg reflector (DBR) was grown by molecular beam epitaxy on an AlN template substrate. The DBR exhibited a peak reflectivity of 83.9% at 246 nm within the deep solar-blind ultraviolet region and a stopband width of 18 nm. The average refractive index contrast for the DBR was 9.25% at 246 nm, which is relatively high compared with that of a traditional Al(Ga)N/(Al)GaN DBR. Simulated results indicated that a 25.5-pair Al0.98In0.02N/Al0.77Ga0.23N DBR will provide a reflectivity higher than 99% and a 19 nm wide stopband with a center wavelength of 246 nm.

Zhang, Lili; Dong, Kexiu; Chen, Dunjun; Liu, Yanli; Xue, Junjun; Lu, Hai; Zhang, Rong; Zheng, Youdou

2013-06-01

383

Optical characterization of Al- and N-polar AlN waveguides for integrated optics  

NASA Astrophysics Data System (ADS)

Dispersion of the extraordinary and ordinary refractive indices of Al- and N-polar AlN waveguides is measured by multiple angle-of-incidence and spectroscopic ellipsometry techniques. The polarity-controlled AlN layers are grown by metal–organic chemical vapor deposition on (0001)-sapphire substrates. Taking into consideration the different surface morphologies of the Al- and N-polar AlN waveguides, we propose two optical models to describe the measured ellipsometry data. The results indicate that there is no difference between the refractive indices of the AlN grown in opposite directions, which confirms the potential of the AlN lateral polar structures for use in nonlinear optical applications based on quasi phase matching.

Rigler, Martin; Buh, Jože; Hoffmann, Marc P.; Kirste, Ronny; Bobea, Milena; Mita, Seiji; Gerhold, Michael D.; Collazo, Ramon; Sitar, Zlatko; Zgonik, Marko

2015-04-01

384

High quality AlGaN grown on ELO AlN/sapphire templates  

NASA Astrophysics Data System (ADS)

The defect structure and the homogeneity of 1-3 µm thick AlxGa1-xN layers grown on epitaxially laterally overgrown (ELO) AlN on patterned AlN/sapphire templates have been investigated in dependence on the miscut direction of the c-plane sapphire substrates, the etching depth into the sapphire and the Al concentration. It was found that shallowly etched AlN/sapphire templates with a 0.25° miscut toward the a-plane provide a smooth surface of ELO AlN and therefore a good Al homogeneity in the overgrown Al0.8Ga0.2N layer. The threading dislocation density in these layers is as low as 5×108 cm-2.

Zeimer, U.; Kueller, V.; Knauer, A.; Mogilatenko, A.; Weyers, M.; Kneissl, M.

2013-08-01

385

Spin reorientation in Al/Metglas 2605S2/Al trilayers induced by magnetoelastic effect  

NASA Astrophysics Data System (ADS)

Mössbauer spectroscopy, in a broad temperature interval of 12-425 K, has been applied to investigate the spin reorientation dynamics caused by the temperature induced magnetoelastic effect on Al(x ?m)/Metglas 2605S2 (20 ?m)/Al(x ?m) trilayers (x =0; 2.5; 5 and 20). It was found that the angle between the average sample magnetization and gamma ray direction (perpendicular to the sample plane) depends on the Al layer thickness. For temperatures smaller than 260 K, saturation of spin reorientation, which can be controlled by adjusting the Al thickness, was reached for Al thicknesses larger than and equal to 5 ?m. For a 20 ?m Al thickness, changes in the F57e atom spin and charge densities have also been observed. A simple spin model has been proposed to describe qualitatively the spin reorientation effect as well as the influence of the Al thickness on the spin reorientation sensitivity.

Moscon, P. S.; Passamani, E. C.; Larica, C.; Takeuchi, A. Y.; Sánchez, F. H.; Zélis, P. Mendoza; Baggio-Saitovitch, Elisa

2008-09-01

386

Ni{sub 3}Al aluminide alloys  

SciTech Connect

This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}Al alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.

Liu, C.T.

1993-10-01

387

Crack-free thick AlGaN grown on sapphire using AlN/AlGaN superlattices for strain management  

NASA Astrophysics Data System (ADS)

We report on an AlN/AlGaN superlattice approach to grow high-Al-content thick n+-AlGaN layers over c-plane sapphire substrates. Insertion of a set of AlN/AlGaN superlattices is shown to significantly reduce the biaxial tensile strain, thereby resulting in 3-?m-thick, crack-free Al0.2Ga0.8N layers. These high-quality, low-sheet-resistive layers are of key importance to avoid current crowding in quaternary AlInGaN multiple-quantum-well deep-ultraviolet light-emitting diodes over sapphire substrates.

Zhang, J. P.; Wang, H. M.; Gaevski, M. E.; Chen, C. Q.; Fareed, Q.; Yang, J. W.; Simin, G.; Khan, M. Asif

2002-05-01

388

Glial cells in ALS: the missing link?  

PubMed

Amyotrophic lateral sclerosis (ALS) was initially known as Charcot's sclerosis, named after the French neurobiologist and physician Jean-Martin Charcot who first described this type of muscular atrophy in the early nineteenth century. In the United States, ALS became widely known as Lou Gehrig's disease after the famous baseball player who succumbed to the disease in the late 1930s. Currently, ALS is the most common motor neuron disease, with a worldwide incidence of 8 cases per 100,000 population per year. Familial forms constitute approximately 5% to 10% of all cases. Onset increases with age, with a peak in the seventh decade and a slight preponderance (relative risk, 1.3-1.5) among men compared with women. Rapid progression of motor neuron loss leads to death an average of 3 to 5 years after symptom onset. The cause of ALS remains unknown and there is still no curative therapy. PMID:18625409

Raibon, Elsa; Todd, Lisa Marie; Möller, Thomas

2008-08-01

389

US 20080226134Al (19) United States  

E-print Network

Classi?cation CONTROLLER (51) Int- Cl (76) Inventors: George DeWitt STETTEN,Pittsburgh, PA (US); Roberta/0226134 A1 STETTEN et al. (43) Pub. Date: Sep. 18, 2008 (54) FINGERTIP VISUAL HAPTIC SENSOR Publication

Stetten, George

390

Everyday Life with ALS: A Practical Guide  

MedlinePLUS

... years ago. ALS: Maintaining Mobility, A Guide to Physical Therapy and Occupational Therapy proved to be an invaluable ... several approaches to communication in ways other than traditional speech. Weakness can limit your ability to accomplish ...

391

Western Baldwin County, AL Grid Interconnection Project  

SciTech Connect

The Objective of this Project was to provide an additional supply of electricity to the affected portions of Baldwin County, AL through the purchase, installation, and operation of certain substation equipment.

Thomas DeBell

2011-09-30

392

Half life of /sup 26/Al  

SciTech Connect

The half-life of /sup 26/Al has been redetermined because of suggestions of an error in the accepted value based on its use in calculating /sup 21/Ne production rates from cosmic rays in meteorites. Two solutions of /sup 26/Al were analyzed for the specific radioactivity and mass spectrometric determination of the /sup 26/Al concentration. The half-life obtained for /sup 26/Al was 7.05 x 10/sup 5/ years +- 3.7% at the two sigma level. This is identical to the accepted value of 7.16 x 10/sup 5/ years and indicates that problems with the /sup 21/Ne production rate is not due to an erroneous half-life.

Norris, T.L.; Gancarz, A.J.; Rokop, D.J.; Thomas, K.W.

1983-01-01

393

Innovative Al Damascene Process for Nanoscale Interconnects  

Microsoft Academic Search

A novel chemical vapor deposition (CVD)-Al technique of ``bottom-up growth'' was developed using methylpyrrolidine alane as a precursor and a (PVD)-TiN\\/CVD-TiN stacked barrier in a damascene structure. Poor step coverage of PVD-TiN caused an absence of PVD-TiN at the bottom of trenches, resulting in selective Al growth. The new method filled a 40-nm-wide trench (aspect ratio = 7.5) completely and

Kyung-In Choi; Sung-Ho Han; Sera Yun; Dae-Yong Kim; Jong Won Hong; Sang Woo Lee; Byung Hee Kim; Sung-Tae Kim; U-In Chung; Joo-Tae Moon; Byung-Il Ryu

2006-01-01

394

Magnetism of Al-Mn quasicrystals  

SciTech Connect

The effect of symmetry and concentration of Mn on the magnetism of Al-Mn quasicrystals has been investigated through self-consistent density-functional calculations using molecular clusters and supercell band-structure schemes. A single Mn atom surrounded by 54 Al atoms in an icosahedral or a cuboctahedral structure is found to be nonmagnetic. However, as the Mn concentration is increased, moments develop on Mn sites whose magnitude and coupling depend on their location.

Liu, F.; Khanna, S.N.; Magaud, L.; Jena, P. (Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)); de Coulon, V.; Reuse, F. (Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, Lausanne (Switzerland)); Jaswal, S.S.; He, X. (Department of Physics and Astronomy, The University of Nebraska-Lincoln, 260 Behlen Laboratory, Lincoln, Nebraska 68588-0111 (United States)); Cyrot-Lackman, F. (Laboratoire d'Etudes des Proprietes Electroniques des Solides, Centre National de la Recherche Scientifique, Boite Postale 166X, 38042 Grenoble, CEDEX France ( ))

1993-07-01

395

17th Annual ALS Users' Association Meeting  

SciTech Connect

It's not exactly Russian roulette, but scheduling October events outdoors is not risk-free, even in usually sunny California. An overflow crowd of more than 400 registered users, ALS staff, and vendors enjoyed a full indoor program featuring science highlights and workshops spread over two and a half days from October 18 to October 20. However, a major storm, heralding the onset of the San Francisco Bay Area rainy season, posed a few weather challenges for the events on the ALS patio.

Robinson, Art; Tamura, Lori

2004-11-29

396

Continuous germanene layer on al(111).  

PubMed

Germanene, a 2D honeycomb structure similar to silicene, has been fabricated on Al(111). The 2D germanene layer covers uniformly the substrate with a large coherence over the Al(111) surface atomic plane. It is characterized by a (3 × 3) superstructure with respect to the substrate lattice, shown by low energy electron diffraction and scanning tunnelling microscopy. First-principles calculations indicate that the Ge atoms accommodate in a very regular atomic configuration with a buckled conformation. PMID:25802988

Derivaz, Mickael; Dentel, Didier; Stephan, Régis; Hanf, Marie-Christine; Mehdaoui, Ahmed; Sonnet, Philippe; Pirri, Carmelo

2015-04-01

397

Structure of decagonal Al-Ni-Rh.  

PubMed

The crystal structure of the decagonal phase in the system Al-Ni-Rh (d-Al-Ni-Rh) was analyzed in the five-dimensional embedding approach based on single-crystal synchrotron X-ray diffraction data. The structure can be described as a quasiperiodic packing of partially overlapping decagonal and pentagonal columnar clusters with ??21?Å diameter and ??4?Å period along the tenfold axis. PMID:25080252

Logvinovich, Dmitry; Simonov, Arkadiy; Steurer, Walter

2014-08-01

398

Effects of Al on nitrogen (NH  

Microsoft Academic Search

After growth for 17 to 36 days on nutrient solutions with NH4NO3 as nitrogen source (pH 4.2) dry matter of sorghum genotype SC0283 was much less affected by Al (1.5 and 3.0 ppm) than that\\u000a of genotype NB9040.\\u000a \\u000a In the absence of Al both cultivars released protons into the nutrient solution as a result of an excess of cationic nutrients

W. G. Keltjens; P. S. R. van Ulden

1987-01-01

399

Interband optical properties of Ni3Al  

Microsoft Academic Search

We present calculations of interband optical conductivity of the compound Ni3Al using the linear-muffin-tin-orbital method. Calculations are performed using constant matrix elements and calculated matrix elements. We find that matrix elements play a significant role in influencing the magnitude of optical conductivity sigma(omega) and the position of peaks. Since Ni3Al is weakly ferromagnetic (magnetic moment equal to 0.31muB per unit

M. A. Khan; Arti Kashyap; A. K. Solanki; T. Nautiyal; S. Auluck

1993-01-01

400

Magnetic Properties of Disordered Fe3Al  

NASA Astrophysics Data System (ADS)

The magnetic properties of Fe3Al powders prepared by filing the ingot in both as-filed and annealed form are studied. Results of Mössbauer, X-ray diffraction and DC magnetization studies show that the magnetic properties are modified due to formation of non-magnetic Fe3AlC0.5 phase due to C intercalated on filing. The hyperfine fields obtained are explained in terms of nearest and next nearest neighbor configurations of 57Fe.

Nehra, J.; Kabra, K.; Jani, S.; Ranjith, P. M.; Lakshmi, N.; Venugopalan, K.

2011-07-01

401

Interdiffusion in the Mg-Al System and Intrinsic Diffusion in ?-Mg2Al3  

NASA Astrophysics Data System (ADS)

Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96 pct) and Al (99.999 pct). Diffusion anneals were carried out at 573 K, 623 K and 673 K (300 °C, 350 °C and 400 °C) for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were used to identify the formation of the intermetallic phases, ?-Mg17Al12, and ?-Mg2Al3, as well as the absence of the ?-Mg23Al30 in the diffusion couples. The thicknesses of the ?-Mg17Al12 and ?-Mg2Al3 phases were measured and the parabolic growth constants were calculated to determine the activation energies for growth. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, ?-Mg17Al12, ?-Mg2Al3, and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Integrated and average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the ?-Mg2Al3 phase, followed by ?-Mg17Al12, Al-solid solution, and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann's analysis ( e.g., marker plane) were determined for the ~ Mg-62 at. pct Al in the ?-Mg2Al3 phase. Activation energies and the pre-exponential factors for the interdiffusion and intrinsic diffusion coefficients were calculated for the temperature range examined. The ?-Mg2Al3 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the ?-Mg2Al3 phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared with the available self-diffusion and impurity diffusion data from the literature. Thermodynamic factor, tracer diffusion coefficients, and atomic mobilities at the marker plane composition were approximated using the available literature values of Mg activity in the ?-Mg2Al3 phase.

Brennan, Sarah; Bermudez, Katrina; Kulkarni, Nagraj S.; Sohn, Yongho

2012-11-01

402

Modeling of precipitation in Al alloys  

SciTech Connect

Objective was the development of a computational model of precipitation from a supersaturated alloy solid solution. The model is based on the formalism of chemical-reaction-rate theory combined with classical descriptions of precipitate thermodynamic properties and a mean-field treatment of diffusion-limited growht and coarsening. For the case of precipitation of Al{sub 3}Sc in supersaturated Al-Sc alloys, it is demonstrated how the model can be used to calculate number densities and size distributions of precipitates as a function of aging time and temperature, including effects of continuous cooling and thermally generated point defects. Application of the model to a specific alloy system requires knowledge of diffusion data, point defect energetics, and thermodynamic properties for bulk phases and interphase interfaces. For interfaces and point defects, thermodynamic data can be difficult to measure and reliable values of defect free energies are often unavailable. For this reason, part of the efforts were devoted to applying semiempirical and first-principles atomistic techniques to the calculation of interfacial and point-defect thermodynamic properties. This report discusses applications for interphase interfaces in the Al-Ag, Al-Sc, and Al-Li alloy systems. We also describe atomistic work aimed at understanding the energetics of vacancy clusters in Al. These clusters serve as sinks for isolated vacancies during aging and their growth can lead to more complex defects, such as dislocation loops, that act as heterogeneous nucleation sites.

Asta, M.; Foiles, S.M.; Wolfer, W.G. [Sandia National Labs., Livermore, CA (United States)] [and others

1996-10-01

403

Differential corticospinal tract degeneration in homozygous ‘D90A’ SOD-1 ALS and sporadic ALS  

PubMed Central

Background The homogeneous genotype and stereotyped phenotype of a unique familial form of amyotrophic lateral sclerosis (ALS) (patients homozygous for aspartate-to-alanine mutations in codon 90 (homD90A) superoxide dismutase 1) provides an ideal model for studying genotype/phenotype interactions and pathological features compared with heterogeneous apparently sporadic ALS. The authors aimed to use diffusion tensor tractography to quantify and compare changes in the intracerebral corticospinal tracts of patients with both forms of ALS, building on previous work using whole-brain voxelwise group analysis. Method 21 sporadic ALS patients, seven homD90A patients and 20 healthy controls underwent 1.5?T diffusion tensor MRI. Patients were assessed using ‘upper motor neuron burden,’ El Escorial and ALSFR-R scales. The intracranial corticospinal tract was assessed using diffusion tensor tractography measures of fractional anisotropy (FA), mean diffusivity, and radial and axial diffusivity obtained from its entire length. Results Corticospinal tract FA was reduced in sporadic ALS patients compared with both homD90A ALS patients and controls. The diffusion measures in sporadic ALS patients were consistent with anterograde (Wallerian) degeneration of the corticospinal tracts. In sporadic ALS, corticospinal tract FA was related to clinical measures. Despite a similar degree of clinical upper motor neuron dysfunction and disability in homD90A ALS patients compared with sporadic ALS, there were no abnormalities in corticospinal tract diffusion measures compared with controls. Conclusions Diffusion tensor tractography has shown axonal degeneration within the intracerebral portion of the corticospinal tract in sporadic ALS patients, but not those with a homogeneous form of familial ALS. This suggests significant genotypic influences on the phenotype of ALS and may provide clues to slower progression of disease in homD90A patients. PMID:21515558

Blain, C R V; Brunton, S; Williams, V C; Leemans, A; Turner, M R; Andersen, P M; Catani, M; Stanton, B R; Ganesalingham, J; Jones, D K; Williams, S C R; Leigh, P N

2011-01-01

404

OVERVIEW NO. 136 DIFFUSION IN THE TiAl SYSTEM  

E-print Network

. Keywords: Intermetallic compounds; Diusion; Radio-tracer method; Theory and modeling 1. INTRODUCTION Intermetallic compounds of the Ti±Al system and alloys based on such compounds are materials of rapidly growing in a-Ti(Al), b-Ti(Al), and intermetallic phases a2-Ti3Al and g-TiAl, are summarized. The results

Mishin, Yuri

405

Optical microcavities and enhanced electroluminescence from electroformed Al-Al2O3-Ag diodes  

NASA Astrophysics Data System (ADS)

Electroluminescence (EL) and electron emission into vacuum (EM) occur when a non-destructive dielectric breakdown of Al-Al2O3-Ag diodes, electroforming, results in the development of a filamentary region in which current-voltage (I-V) characteristics exhibit voltage-controlled negative resistance. The temperature dependence of I-V curves, EM, and, particularly, EL of Al-Al2O3-Ag diodes with anodic Al2O3 thicknesses between 12 nm and 30 nm, has been studied. Two filters, a long-pass (LP) filter with transmission of photons with energies less than 3.0 eV and a short-pass (SP) filter with photon transmission between 3.0 and 4.0 eV, have been used to characterize EL. The voltage threshold for EL with the LP filter, VLP, is ˜1.5 V. VLP is nearly independent of Al2O3 thickness and of temperature and is 0.3-0.6 V less than the threshold voltage for EL for the SP filter, VSP. EL intensity is primarily between 1.8 and 3.0 eV when the bias voltage, VS ? 7 V. EL in the thinnest diodes is enhanced compared to EL in thicker diodes. For increasing VS, for diodes with the smallest Al2O3 thicknesses, there is a maximum EL intensity, LMX, at a voltage, VLMX, followed by a decrease to a plateau. LMX and EL intensity at 4.0 V in the plateau region depend exponentially on Al2O3 thickness. The ratio of LMX at 295 K for a diode with 12 nm of Al2O3 to LMX for a diode with 25 nm of Al2O3 is ˜140. The ratio of EL intensity with the LP filter to EL intensity with the SP filter, LP/SP, varies between ˜3 and ˜35; it depends on Al2O3 thickness and VS. Enhanced EL is attributed to the increase of the spontaneous emission rate of a dipole in a non-resonant optical microcavity. EL photons interact with the Ag and Al films to create surface plasmon polaritons (SPPs) at the metal-Al2O3 interfaces. SPPs generate large electromagnetic fields in the filamentary region of the electroformed Al-Al2O3-Ag diode, which then acts as an optical microcavity. A model is proposed for electronic processes in electroformed Al-Al2O3-Ag diodes.

Hickmott, T. W.

2013-12-01

406

77 FR 73732 - In the Matter of the Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Front, Jabhat al-Nusrah, Jabhet al-Nusra, The Victory Front, Al Nusrah Front...aka Jabhat al-Nusrah, aka Jabhet al-Nusra, aka The Victory Front, aka Al...Front, Jabhat al-Nusrah, Jabhet al-Nusra, The Victory Front, Al Nusrah...

2012-12-11

407

Comment on ``A new interpretation of Weimer et al.'s solar wind propagation delay technique'' by Bargatze et al.  

NASA Astrophysics Data System (ADS)

In a recent article, Bargatze et al. (2005) have identified why the implementation of the minimum variance analysis (MVAB) by Weimer et al. (2003), even though based on an erroneous variance matrix, has been successful in estimating the orientation of the "phase fronts" and the resulting propagation delays of the interplanetary magnetic field (IMF). They recommend further testing of the Weimer analysis as a space weather forecasting tool. In this comment we stress that the Weimer et al. implementation of MVAB closely mimics the results of a well-known version of MVAB that is constrained by the condition that the average field along the phase front normals is zero. This version of MVAB starts from the correct variance matrix, whereas the Weimer analysis is based on an unphysical matrix resulting from a programming error. We recommend that the constrained MVAB, originally developed by Sonnerup and Cahill (1968) and later recast into a more convenient form by A.V. Khrabrov be used instead. The Khrabrov method, which we refer to as MVAB-0, has been tested at the Earth's magnetopause by Sonnerup and Scheible (1998) and more recently by Haaland et al. (2004) and Sonnerup et al. (2004).

Haaland, S.; Paschmann, G.; Sonnerup, B. U. Ã.-.

2006-06-01

408

Dry sliding wear mechanism for P\\/M austenitic stainless steels and their composites containing Al 2O 3 and Y 2O 3 particles  

Microsoft Academic Search

Austenitic stainless steels are used in applications demanding general corrosion resistance at room or moderate operating temperatures. However, their use is often limited by the relative softness of these materials and their suceptibility to wear and galling. The present investigation deals with the dry sliding wear behaviour of two P\\/M austenitic stainless steels (AISI 304L and 316L) and their composites

M. Vardavoulias; M. Jeandin; F. Velasco; J. M. Torralba

1996-01-01

409

Theoretical studies of Ni/sub 3/Al and NiAl with impurities  

SciTech Connect

Intermetallic compound has been extensively studied because of their superior properties in strength, low creep rate, and high melting point. But most of the systems have room temperature ductility problems, like Ll/sub 2/ and B2 compounds. Both Ll/sub 2/ Ni/sub 3/Al and B2 NiAl exhibit intergranular fracture mode. Understanding grain boundaries in these materials is of particular importance since intergranular fracture limits the applicability of these otherwise promising material. In an effort trying to understand the fracture mechanism, we have used embedded atom potentials to study the properties of Ni/sub 3/Al and NiAl. We also consider the effect of boron, sulfur, and nickel segregation on the strength of grain boundaries in Ni/sub 3/Al and NiAl. 22 refs., 2 figs.

Chen, S.P.; Voter, A.F.; Boring, A.M.; Albers, R.C.; Hay, P.J.

1988-01-01

410

Analog resistive switching behavior of Al/Nb2O5/Al device  

NASA Astrophysics Data System (ADS)

Resistive switching effects in metal–insulator–metal (MIM) structures are strongly influenced by the electrode materials. In this work a platinum-free symmetric Al/Nb2O5/Al device is compared to a device with platinum bottom electrode. For the device with the platinum bottom electrode, filamentary based resistive switching with good data retention was observed up to 125 °C. For the Al/Nb2O5/Al device, an area dependent pure electronic based resistive switching was observed. Electron trapping at the bottom electrode interface is responsible for the observed analog switching behavior which makes an Al/Nb2O5/Al device suitable for neuromorphic applications.

Mähne, H.; Wylezich, H.; Hanzig, F.; Slesazeck, S.; Rafaja, D.; Mikolajick, T.

2014-10-01

411

Effects of Al(III) and Nano-Al13 Species on Malate Dehydrogenase Activity  

PubMed Central

The effects of different aluminum species on malate dehydrogenase (MDH) activity were investigated by monitoring amperometric i-t curves for the oxidation of NADH at low overpotential using a functionalized multi-wall nanotube (MWNT) modified glass carbon electrode (GCE). The results showed that Al(III) and Al13 can activate the enzymatic activity of MDH, and the activation reaches maximum levels as the Al(III) and Al13 concentration increase. Our study also found that the effects of Al(III) and Al13 on the activity of MDH depended on the pH value and aluminum speciation. Electrochemical and circular dichroism spectra methods were applied to study the effects of nano-sized aluminum compounds on biomolecules. PMID:22163924

Yang, Xiaodi; Cai, Ling; Peng, Yu; Li, Huihui; Chen, Rong Fu; Shen, Ren Fang

2011-01-01

412

Short-period superlattices of AlN/Al0.08Ga0.92N grown on AlN substrates S. A. Nikishin,a)  

E-print Network

energy electron diffraction (RHEED). The Al-face AlN substrates11 were nominally (0001) ori- ented and Nano Tech Center, Texas Tech University, Lubbock, Texas 79409-3102 M. Holtz Nano Tech Center-source molecular-beam epitaxy with ammonia on Al face of AlN (0001) substrates. A significant reduction

Holtz, Mark

413

Two-Phase (TiAl+TiCrAl) Coating Alloys for Titanium Aluminides  

NASA Technical Reports Server (NTRS)

A coating for protecting titanium aluminide alloys, including the TiAl gamma + Ti3Al (alpha(sub 2)) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C. is disclosed. This protective coating consists essentially of titanium, aluminum. and chromium in the following approximate atomic ratio: Ti(41.5-34.5)Al(49-53)Cr(9.5-12.5)

Brady, Michael P. (Inventor); Smialek, James L. (Inventor); Brindley, William J. (Inventor)

1998-01-01

414

Surface Superstructures of Ordered Layers of Al2O3 on Ni3Al(001)  

Microsoft Academic Search

Atomically ordered Al2O3 obtained by thermal oxidation of the Ni3Al(001) surface was studied using scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). LEED analysis has shown that oxidation at 800 and 1100 K forms two different structural phases of Al2O3. Detailed STM studies of both phases also reveal remarkable differences in surface pattern structure and arrangement of the domains.

Oleg Kurnosikov; Cees F. J. Flipse; Henk J. M. Swagten; Bert Koopmans; Wim J. M. de Jonge

2006-01-01

415

Comparing characteristics of serrations in Al–Li and Al–Mg alloys  

Microsoft Academic Search

Characteristics of serrations in the flow stress–strain curves of Al–1Mg and Al–2Li alloys, obtained from tensile tests, are analyzed and compared. The analysis includes stress drop, drop time and reload time at various ageing durations of the alloys. Changes in distributions of the stress drops and the drop time with changing the ageing duration differ markedly in Al–2Li from those

Baohui Tian

2003-01-01

416

Molecular beam epitaxial regrowth on insitu plasma-etched AlAs\\/AlGaAs heterostructures  

Microsoft Academic Search

Epitaxial regrowth by solid-source molecular beam epitaxy (MBE) on dry etched heterostructures possessing exposed AlAs surfaces is accomplished for the first time using a vacuum integrated processing. Samples composed of multilayers of AlAs and AlGaAs are patterned with a SiO2 mask and are anisotropically etched using a low damage electron cyclotron resonance (ECR) SiCl4 plasma process. Etched samples are transferred

Kent D. Choquette; M. Hong; R. S. Freund; S. N. G. Chu; J. P. Mannaerts; R. C. Wetzel; R. E. Leibenguth

1992-01-01

417

NMR measurements and hybridization behavior in Al_3Zr, Al_3Hf, and related intermetallics  

Microsoft Academic Search

We report ^27Al NMR measurements on aluminum-rich intermetallics, including the DO_23-structured alloys Al_3Zr and Al_3Hf, and related close-packed structures. We determined the quadrupole splittings and Knight shifts, giving site-dependent structural information. The Knight shift tensors indicate strong directional bonding in the DO_23 alloys, despite the modified close-pack structures. This is especially true for sites I and III. The non-zero asymmetry

Chin Shan Lue Ross Jr.

2001-01-01

418

Structure of 26Al studied by one - nucleon transfer reaction 27Al(d,t)  

NASA Astrophysics Data System (ADS)

The excited states of 26Al have been produced and studied using 27Al(d,t) reaction with 25 MeV deuteron as projectile. Optical model potential parameters were extracted from the measured elastic scattering angular distribution. Zero range distorted wave Born approximation analysis for the ground and 0.223 MeV states of 26Al have been done. The spectroscopic factors calculated for these states are found to be in good agreement with the previously reported values.

Srivastava, Vishal; Bhattacharya, C.; Rana, T. K.; Manna, S.; Kundu, S.; Bhattacharya, S.; Banerjee, K.; Roy, P.; Pandey, R.; Mukherjee, G.; Ghosh, T. K.; Meena, J. K.; Roy, T.; Chaudhuri, A.; Sinha, M.; Saha, A.; Dey, A.; Asgar, Md. A.; Roy, Subinit; Shaikh, Md. M.

2015-01-01

419

Remarks on Peinado et al.'s Analysis of J3Gen.  

PubMed

Peinado et al. analyzed the security of the J3Gen pseudorandom number generator proposed by Melià-Seguí et al., and claimed weaknesses regarding its security properties. They also presented a deterministic attack based on the decimation of the J3Gen output sequences. We show that the assumptions made by Peinado et al. are not correct and that the proposed deterministic attack against J3Gen does not hold in practice. PMID:25781510

Garcia-Alfaro, Joaquin; Herrera-Joancomartí, Jordi; Melià-Seguí, Joan

2015-01-01

420

Thermodynamic properties of alloys of the Al-Co and Al-Co-Sc systems  

NASA Astrophysics Data System (ADS)

Enthalpies of mixing for melts of the binary Al-Co system at 1870 K in the range 0 < x Co < 0.25, and at 1620 K, 0 < x Co < 0.12, are investigated by means of isoperibolic calorimetry. Enthalpies of mixing for melts of the ternary Al-Co-Sc system are investigated at 1870 K for sections Al0.75(1 - x)Co0.25(1 - x)Sc x , 0 < x < 0.024, and Al0.88(1 - x)Co0.12(1 - x)Sc x , 0 < x < 0.044. Using the literature data on the enthalpies of mixing for liquid and solid alloys, the activities of melt components, and the phase diagram of the Al-Co system, the thermodynamic properties of liquid and solid alloys of the Al-Co system over a wide range of temperatures and compositions are calculated using a software package of our own design, based on the model of ideal associated solutions (IAS). The enthalpies of mixing and the liquidus surface of the phase diagram of the ternary Al-Co-Sc system over the interval of concentrations are estimated by modeling with data on binary boundary subsystems. All of the components of both the binary Al-Co and ternary Al-Co-Sc systems tend to interact with one another quite strongly: ? H min(Al-Co) = -32.5 kJ/mol at x Co = 0.44; ? H min(Al-Co-Sc) = -46 kJ/mol for Al0.4Co0.3Sc0.3 (estimated).

Shevchenko, M. A.; Berezutskii, V. V.; Ivanov, M. I.; Kudin, V. G.; Sudavtsova, V. S.

2014-05-01

421

The lowest ionization potentials of Al2  

NASA Technical Reports Server (NTRS)

Potential curves for the lowest two electronic states (X 2 sigma g + and A 2 pi u) of Al2(+) were computed using complete active space SCF/multireference CI wave functions and large Gaussian basis sets. The lowest observable vertical ionization potential (to Al2(+) X 2 sigma g +) of the Al2 X 3 pi u ground state is calculated to occur around 6.1 eV, in excellent agreement with the experimental range of 6.0 to 6.42 eV obtained in recent cluster ionization studies by Cox and co-workers. The second vertical ionization potential (to Al2(+) A 2 pi u) occurs near 6.4 eV, also within the experimental range. The adiabatic IP of 5.90 eV is in good agreement with the value of 5.8 to 6.1 eV deduced by Hanley and co-workers from the difference in thresholds between collision induced dissociation processes of Al3(+). The computed IP values are somewhat larger than those deduced from branching ratios in cluster fragmentation experiments by Jarrold and co-workers. The observation of an ionization threshold below 6.42 eV is shown to be incompatible with an Al2 ground electronic state assignment of 3 sigma g -, but the separation between the two lowest states of Al2 is so small that it is likely that both are populated in the experiments, so that this does not provide unambiguous support for the recent theoretical assignment of the ground state as 3 pi u.

Bauschlicher, Charles W., Jr.; Barnes, Leslie A.; Taylor, Peter R.

1988-01-01

422

77 FR 40492 - Revocation of Class D Airspace; Andalusia, AL; and Amendment of Class E Airspace; Fort Rucker, AL  

Federal Register 2010, 2011, 2012, 2013, 2014

...also updates the geographic coordinates of the above airport; Cairns AAF, Ft. Rucker, AL; and Florala Municipal, AL, to be...ASO AL E5 Fort Rucker, AL [Amended] Fort Rucker, Cairns AAF, AL (Lat. 31[deg]16'33'' N., long....

2012-07-10

423

Long range order and vacancy properties in Al-rich Fe{sub 3}Al and Fe{sub 3}Al(Cr) alloys  

SciTech Connect

Neutron powder diffraction measurements have been carried out in situ from room temperature to about 100 C in Fe28Al (28 at.% Al), Fe32.5Al (32.5 at.% Al) and Fe28Al15Cr (28 at.% Al, 5 at.% Cr) alloys. X-ray diffraction and TEM studies provided supporting information. The data were analyzed to obtain information about the temperature dependence of the DO{sub 3} and B2 long range order parameters, the location of the Cr atoms and their effect on the ordering energies, and on the vacancy formation and migration properties in Fe28Al and Fe32.5Al alloys. The location of the ternary alloying addition in DO{sub 3} and B2 ordered Al-rich Fe{sub 3}Al is shown to be consistent with considerations of interatomic bond energies.

Kim, S.M. [AECL, Chalk River, Ontario (Canada). Chalk River Labs.] [AECL, Chalk River, Ontario (Canada). Chalk River Labs.; Morris, D.G. [Univ. of Neuchatel (Switzerland). Inst. of Structural Metallurgy] [Univ. of Neuchatel (Switzerland). Inst. of Structural Metallurgy

1998-05-01

424

Possible Involvement of Al-Induced Electrical Signals in Al Tolerance in Wheat.  

PubMed Central

The relationship between Al-induced depolarization of root-cell transmembrane electrical potentials (Em) and Al tolerance in wheat (Triticum aestivum L.) was investigated. Al exposure induced depolarizations of Em in the Al-tolerant wheat cultivars Atlas and ET3, but not in the Al-sensitive wheat cultivars Scout and ES3. The depolarizations of Em occured in root cap cells and as far back as 10 mm from the root tip. The depolarization was specific to Al3+; no depolarization was observed when roots were exposed to the rhizotoxic trivalent cation La3+. The Al-induced depolarization occurred in the presence of anion-channel antagonists that blocked the release of malate, indicating that the depolarization is not due to the electrogenic efflux of malate2-. K+-induced depolarizations in the root cap were of the same magnitude as Al-induced depolarizations, but did not trigger malate release, indicating that Al-induced depolarization of root cap cell membrane potentials is probably linked to, but is not sufficient to trigger, malate release. PMID:12223834

Papernik, L. A.; Kochian, L. V.

1997-01-01

425

High temperature deformation of NiAl and CoAl  

NASA Technical Reports Server (NTRS)

The high temperature mechanical properties of the aluminides are reviewed with respect to their potential as high temperature structural materials. It is shown that NiAl and CoAl are substantially stronger than the pure metals Ni and Co at high temperatures and approach the strength of some superalloys, particularly when those superalloys are tested in "weak" directions. The factors that limit and control the high temperature strengths of NiAl and CoAl are examined to provide a basis for the development of intermetallic alloys of this type.

Nix, W. D.

1982-01-01

426

Achieving conductive high Al-content AlGaN alloys for deep UV photonics  

NASA Astrophysics Data System (ADS)

Recent progresses in epitaxial growth and fundamental studies on electrical and optical properties of high Al-content AlGaN alloys with Si, Mg, and Zn doping are presented. For Si doped Al xGa1- xN, the Si activation energy was determined for x = 0 up to 1, and the resistivity of n-Al xGa1- xN was found to increases by one order of magnitude when Al content is increased by ~ 8%. From photoluminescence (PL) studies, three groups of deep impurity transitions were observed, related with deep level acceptors involving cation vacancy and its complexes: (VIII) 3-, (VIII-complex)2, and (VIII-complex) 1-, which are electron traps and compensating centers. By optimizing the growth processes to reduce the densities of cation vacancy and its complexes, the n-type conductivity of Al xGa1- xN was significantly improved. A record low room temperature n-type resistivity of 0.0075 ?•cm has been obtained for Al 0.7Ga 0.3N, and n-type conduction in pure AlN has also been achieved. We also review the electrical and optical measurement results of Mgdoped AlGaN and AlN. It was found that the overall material quality and conductivity of Mg-doped AlN are strongly correlated with the PL emission intensity of the nitrogen vacancy (V N 3+) related transition. Improved conductivity was obtained by suppressing the V N 3+ related emission line, which was attributed to the reduced hole compensation by V N 3+. With the identification of the emission peaks associated with V N 3+ hole compensating centers, the p-type conductivity of high Al-content AlGaN alloys was improved by monitoring and suppressing the intensity of the V N 3+ related emission lines. P-type conduction in Al xGa1- xN (x > 0.7) was confirmed at elevated temperatures (> 700 K). The possibility of using Zn as an alternative p-type dopant was also studied. It was found that contrary to the calculation, the energy level of Zn acceptor in AlN was about 0.74 eV, which is 0.23 eV deeper than Mg level in AlN.

Fan, Z. Y.; Lin, J. Y.; Jiang, H. X.

2007-02-01

427

Photoemission from Al Alloys during Tensile Deformation  

NASA Astrophysics Data System (ADS)

We report simultaneous measurements of strain and photoelectron emission intensity from high purity Al (1350), Al-Mg (5052), Al-Mn (3003), Al-Cu (2024) and Al-Mg-Si (6061) alloys under uniaxial tension due to pulsed excimer laser radiation (248-nm). The photoemission signals are sensitive to deformation-induced changes in surface morphology, including the formation of slip lines and slip bands. In the early stages of deformation (strain Â¡Ü 0.03), the photoemission intensity increases gradually in a nonlinear fashion. Depending on sample composition and heat treatment, the photoemission intensity subsequently grows linearly until the accumulated strain reaches about 0.20. Finally, the photoemission intensity increases parabolically until failure. The onset of strain localization corresponds to the transition from linear to parabolic growth. A constitutional model incorporating microstructure evolution and work-hardening during tensile deformation is proposed to qualitatively interpret the growth of the photoemission signals as a function of strain. The photoemission signals from the tested alloys are interpreted in terms of the effect of surface treatment, work function, microstructure, and composition on the development of dislocation structures during deformation.

Cai, Mingdong; Langford, Stephen; Levine, Lyle; Dickinson, Thomas

2004-03-01

428

Mg-doped Al-rich AlGaN alloys for deep UV emitters  

NASA Astrophysics Data System (ADS)

Mg doped Al-rich AlGaN epilayers with Al content as high as 0.7 is needed for obtaining deep UV LEDs with wavelengths shorter than 300 nm. This is one of the most crucial layers in deep UV LEDs and plays an important role for electron blocking and affects the hole injection into the active layer. Not only is this layer critical for the efficiency of deep UV LEDs, it could also introduce long wavelength emission components in UV LEDs. However, it is difficult to obtain high quality Mg doped Al-rich AlGaN epilayers and the resistivity of the grown films is usually extremely high. We report here on the growth, optical and electrical properties of Mg doped Al0.7Ga0.3N epilayers. Mg doped Al0.7Ga0.3N epilayers of high crystalline and optical qualities have been achieved after optimizing MOCVD growth conditions. Moreover, we have obtained a resistivity around 12,000 ? cm (near the theoretical limit with Mg doping) at room temperature and confirmed p-type conduction at elevated temperatures for optimized Mg-doped Al0.7Ga0.3N epilayers. The growth conditions of the optimized epilayer have been incorporated into deep UV LEDs with wavelength shorter than 300 nm. A significant enhancement in power output with a reduction in forward voltage, Vf, was obtained by employing this optimized Mg doped Al0.7Ga0.3N epilayer as an electron blocking layer. The long wavelength emission components in deep UV LEDs were also significantly suppressed. The fundamental limit for achieving p-type Al-rich AlGaN alloys is also discussed.

Nakarmi, Mim L.; Kim, Kyoung Hoon; Zhu, Kai; Lin, Jing Yu; Jiang, Hong Xing

2004-10-01

429

ALS and Frontotemporal Dysfunction: A Review  

PubMed Central

Though once believed to be a disease that was limited to the motor system, it is now apparent that amyotrophic lateral sclerosis (ALS) may be associated with cognitive changes in some patients. Changes are consistent with frontotemporal dysfunction, and may range from mild abnormalities only recognized with formal neuropsychological testing, to profound frontotemporal dementia (FTD). Executive function, behavior, and language are the most likely areas to be involved. Screening helpful in detecting abnormalities includes verbal or categorical fluency, behavioral inventories filled out by the caregiver, and evaluation for the presence of depression and pseudobulbar affect. Patients with cognitive dysfunction have shortened survival and may be less compliant with recommendations regarding use of feeding tubes and noninvasive ventilation. Evolving knowledge of genetic and pathological links between ALS and FTD has allowed us to better understand the overlapping spectrum of ALS and FTD. PMID:22919484

Achi, Eugene Y.; Rudnicki, Stacy A.

2012-01-01

430

The mechanical properties of FeAl  

SciTech Connect

Only in the last few years has progress been made in obtaining reproducible mechanical properties data for FeAl. Two sets of observations are the foundation of this progress. The first is that the large vacancy concentrations that exist in FeAl at high temperature are easily retained at low temperature and that these strongly affect the low-temperature mechanical properties. The second is that RT ductility is adversely affected by water vapor. Purpose of this paper is not to present a comprehensive overview of the mechanical properties of FeAl but rather to highlight our understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed the discovery of the above two effects. 87 refs, 9 figs.

Baker, I. [Dartmouth Coll., Hanover, NH (United States); George, E.P. [Oak Ridge National Lab., TN (United States)

1996-12-31

431

[Al-Biruni--a universal scientist].  

PubMed

Al-Biruni's was of Persian descent. He was born in Horesmiya and had studied mathematics, history and medicine. Acquiring knowledge from these sciences, he wrote an outstanding work on chronology of several nations and devoted it to Ziyarit ruler Kabus. He made a chronological overview of calendars from many nations, including Persians, Greeks, Egyptians, Jews, Melkitian and Nestorian Christians, Sabeyaans as well as the old Arabs. Data presented in the work, according to the later authors, were taken from very reliable sources. He was contemporary of Ibn-Sina, and thanks to their friendship, they have discussed very much miscellaneous topics. He belonged to the group of scholars, taken by Gaznevian Soultan Mahmud to a long journey to India. Afterwards Al-Biruni wrote and published detailed work "Description of India"--a work on cultural history of India. Due to excellent abilities of Al-Biruni as a philosopher and scholar, there are still significant and reliable notes about buddhistic philosophy, structure of castes and Brahmans' life style. In this Al-Biruni's masterpiece, there are many comparative analysis of Suffism and certain Indian philosophical methods. Al-Biruni's most important work is "Pharmacopoeia"--"Kitab al-saydala", which brilliantly describes all medicaments. This work has been published in many languages. He also wrote few works on astronomy and astrology. In those works he has explained some astrological events through scientific approach in a such peculiar way that nobody has ever explained before. He was also interested in sciences like geology, mineralology, geography, mathematics, psychology and many others. PMID:10386051

Kujundzi?, E; Masi?, I

1999-01-01

432

Nb3Al Development for HEP Applications  

SciTech Connect

Recent developments in Nb3Al strand for HEP applications are presented and discussed. The present state of available precursor is detailed. Two routes have been shown to lead to successful construction of MF NbAl composite wires. An extrusion method has so far produced the highest filament counts and smallest filament diameters, but requires more processing steps. A direct restack and draw approach has also been demonstrated which minimizes the number of processing steps while still leading to a high performance conductor. This latter route also allows for a lower cost per billet, potentially allowing the exploration of more process parameters.

Sumption, M.D.; Buta, F.; Collings, E.W. [Laboratories for Applied Superconductivity and Magnetism (LASM), MSE Dept, The Ohio State University, Columbus, OH 43210 (United States); Tomsic, M.; Phillips, J.; McFadden, K. [Hyper Tech Research Inc., Troy, OH 45373 (United States); Wu, X

2004-06-28

433

An Alternative Perspective on von Winterfeldt et al.'s (1997) Test of Consequence Monotonicity  

ERIC Educational Resources Information Center

D. von Winterfeldt, N.-K. Chung, R. D. Luce, and Y. Cho (see record 1997-03378-008) provided several tests for consequence monotonicity of choice or judgment, using certainty equivalents of gambles. The authors reaxiomatized consequence monotonicity in a probabilistic framework and reanalyzed von Winterfeldt et al.'s main experiment via a…

Ho, Moon-Ho R.; Regenwetter, Michel; Niederee, Reinhard; Heyer, Dieter

2005-01-01

434

A unique description of steady state deformation of Al and Al-Mg alloys  

Microsoft Academic Search

In this work, simple mathematical relations between the plastic strain rate, the flow stress and the temperature for steady state deformation of aluminium alloys are proposed. The expressions are based on the corresponding formula for pure Al considered as a reference material. A ‘master curve’ representing this relation for Al was obtained through a compilation of a large array of

G. Bermig; A. Bartels; H. Mecking; Y. Estrin

1997-01-01

435

Thermal behavior of Al and Al3 at. % Ge thin films on Si wafers  

Microsoft Academic Search

The mechanical stresses of a pure Al film and a low-thermal-expansion Al-3 at. % Ge thin film on (100) Si wafers are measured and compared in the temperature range of room temperature to 400 °C by the vibrating membrane method. The results are discussed including the comparison with those obtained by the popular wafer bending method. It was found that

B. S. Lim; W. C. Pritchet; K. P. Rodbell; K. N. Tu

1993-01-01

436

^27Al-NMR Study of the Spinel Compound CoAl2O4  

NASA Astrophysics Data System (ADS)

CoAl2O4, a geometrically frustrated magnet, is believed to be located in the vicinity of a quantum melting point of the AFM ordered state. In CoAl2O4, magnetic frustration originates from Co^2+(S = 3/2) spins on the tetrahedral A-site via non-magnetic Al ions occupying the octahedral B-site. To study the magnetic properties of CoAl2O4 from a microscopic point of view, we have carried out ^27Al-NMR measurements using a well-characterized powder sample of CoAl2O4. The temperature dependence of the magnetic susceptibility ? shows a broad peak around 15 K and does not show any difference in zero-field-cooled and field-cooled measurements. ^27Al-NMR spectra at 9.3 MHz (H = 0.84 T) show seven peaks characterized by quadrupolar splitting with ?Q= 0.55 MHz at temperatures above 10 K. Below 10 K, the spectrum broadens suddenly. We also observe a peak of 1/T1 of ^27Al at 10 K. These NMR results clearly indicate magnetic ordering at 10 K, although ? does not exhibit any signature of long-range magnetic ordering.

Roy, Beas; Pandey, Abhishek; Johnston, David C.; Furukawa, Yuji

2013-03-01

437

Electronic circuits having NiAl and Ni.sub.3 Al substrates  

DOEpatents

An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

Deevi, Seetharama C. (Midlothian, VA); Sikka, Vinod K. (Oak Ridge, TN)

1999-01-01

438

Structures of AlN/VN superlattices with different AlN layer thicknesses  

E-print Network

, is characterized by high ionicity, short bond length, low compressibility, high thermal conductivity, and a wide B1-AlN, suggests that the phase transition is martensitic. II. EXPERIMENTAL PROCEDURES AlN/VN superlattices were grown on MgO(001) sub- strates in an ultrahigh vacuum dc-magnetron sputtering system that has

Marks, Laurence D.

439

Replication and Extension of Little et al.'s (2003) Forms and Functions of Aggression Measure  

ERIC Educational Resources Information Center

The goal of the current study was to replicate the confirmatory factor analysis of Little et al.'s (2003) aggression measure in an American sample of 69 children (mean age = 12.93 years; SD = 1.27). Although an exact replication of the original model could not be estimated given the small sample, a modified model representing a conceptual…

Fite, Paula J.; Stauffacher, Kirstin; Ostrov, Jamie M.; Colder, Craig R.

2008-01-01

440

Melting, Processing, and Properties of Disordered Fe-Al and Fe-Al-C Based Alloys  

NASA Astrophysics Data System (ADS)

This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-Al alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-Al-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-Al alloys has been studied in detail. Fe-7 wt.% Al alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% Al alloys has also been examined. The results indicate that Fe-Al and Fe-Al-C alloys containing about 7 wt.% Al are potential lightweight steels.

Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.

2014-09-01

441

University of AlAskA AnchorAge AlAskA Justice Forum  

E-print Network

University of AlAskA AnchorAge AlAskA Justice Forum A PUblicAtion of the JUstice center Fall 2013 in Alaska and nationally (page 2). · An update on the work of the Alaska Prisoner Reentry Task Force (page 5 Collateral Consequences and Reentry in Alaska: An Update Deborah Periman "Our legal system has created

Pantaleone, Jim

442

University of AlAskA AnchorAge AlAskA Justice Forum  

E-print Network

University of AlAskA AnchorAge AlAskA Justice Forum A PUblicAtion of the JUstice center Summer 2013 Vol. 30, No. 2 Please see Alcohol, page 13 Reducing Sales of Alcohol to Underage Persons in Alaska within a few hours) in the past month, more than one quarter of youth in public high schools in Alaska

Pantaleone, Jim

443

AlAskA Justice Forum University of AlAskA AnchorAge  

E-print Network

AlAskA Justice Forum University of AlAskA AnchorAge A PUblicAtion of the JUstice center Fall 2008 to Alaska State Troopers Marny Rivera, André B. Rosay, Darryl S. Wood, Greg Postle, and Katherine Te violence is an undeniable urban and rural problem in Alaska and the nation. Detailed data on domestic

Pantaleone, Jim

444

Directional Solidification and Mechanical Properties of NiAl-NiAlTa Alloys  

NASA Technical Reports Server (NTRS)

Directional solidification of eutectic alloys is a promising technique for producing in-situ composite materials exhibiting a balance of properties. Consequently, the microstructure, creep strength and fracture toughness of directionally solidified NiAl-NiAlTa alloys were investigated. Directional solidification was performed by containerless processing techniques to minimize alloy contamination. The eutectic composition was found to be NiAl-15.5 at% Ta and well-aligned microstructures were produced at this composition. A near-eutectic alloy of NiAl-14.5Ta was also investigated. Directional solidification of the near-eutectic composition resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The off-eutectic alloy exhibited promising compressive creep strengths compared to other NiAl-based intermetallics, while preliminary testing indicated that the eutectic alloy was competitive with Ni-base single crystal superalloys. The room temperature toughness of these two-phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa.

Johnson, D. R.; Chen, X. F.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

1995-01-01

445

Nucleosynthesis of Al26 in massive stars: New Al27 states above ? and neutron emission thresholds  

NASA Astrophysics Data System (ADS)

The 26Al radioisotope is of great importance for understanding the chemical and dynamical evolution of our galaxy. Among the possible stellar sources, massive stars are believed to be the main producer of this radioisotope. Understanding 26Al nucleosynthesis in massive stars requires estimates of the thermonuclear reaction rates of the Al26(n,p)26Mg, Al26(n,?)23Na, and Na23(?,p)26Mg reactions. These reaction rates depend on the spectroscopic properties of 27Al states above the neutron and alpha thresholds. In this context, the Al27(p,p')27Al* reaction was studied at 18 MeV using a high-resolution Enge Split-Pole spectrometer. States from the ground state up to excitation energies of ?14 MeV were populated. While up to the 23Na + ? threshold no additional states are observed, we report for the first time 30 new levels above the 23Na + ? threshold and more than 30 new states above the 26Al + n threshold for which excitation energies are determined with an uncertainty of 4-5 keV.

Benamara, S.; de Séréville, N.; Laird, A. M.; Hammache, F.; Stefan, I.; Roussel, P.; Ancelin, S.; Assié, M.; Coc, A.; Deloncle, I.; Fox, S. P.; Kiener, J.; Lefebvre, L.; Lefebvre-Schuhl, A.; Mavilla, G.; Morfouace, P.; Sánchez-Benítez, Á. M.; Perrot, L.; Sinha, M.; Tatischeff, V.; Vandebrouck, M.

2014-06-01

446

Electronic structure and bonding at the Alterminated Al(111)/Al2O3(0001) interface: A first principles study  

E-print Network

the mechanical properties of an interface, is the ideal work of adhesion, Ï ,[1] which is defined as the bondElectronic structure and bonding at the Al­terminated Al(111)/«­Al2O3(0001) interface: A first to determine the bonding character of the Al­terminated Al(111)/«­Al2O3(0001) interface. By using an optimized

Adams, James B

447

An impedance study of complex Al/Cu-Al2O3 electrode  

NASA Astrophysics Data System (ADS)

Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al2O3 electrode composition was approved by equivalent circuit analysis, optical and scanning electron microscope methods. The most optimal Cu deposition mode using internal electrolysis was determined. The obtained results are promising for future electrochemical fabrication of nanostructures directly on Al surfaces by internal electrolysis.

Denisova, J.; Katkevics, J.; Erts, D.; Viksna, A.

2011-06-01

448

Analysis of interface trap states in InAlN/AlN/GaN heterostructures  

NASA Astrophysics Data System (ADS)

Gate-source frequency-dependent capacitance and conductance measurements were performed on the In0.17Al0.83N/AlN/GaN heterostructure field-effect transistor with side-Ohmic contacts to study the characteristics of trap states at the interface between InAlN and GaN. The values of interface trap state density and time constant were determined to be (0.96-3.36) × 1013 cm-2 eV-1 and (0.29-1.61) ?s, respectively. We calculated the strain in the InAlN barrier layer under the gate and found that the InAlN barrier layer was compressively strained with the in-plane strain of 1.31%. This is a possible reason for such a high interface trap state density which is not as low as supposed in the lattice-matched heterostructures.

Zhou, Yang; Lin, Zhaojun; Luan, Chongbiao; Zhao, Jingtao; Yang, Qihao; Yang, Ming; Wang, Yutang; Feng, Zhihong; Lv, Yuanjie

2014-09-01

449

Properties and structure of oxidized coatings deposited onto Al-Cu and Al-Mg alloys  

NASA Astrophysics Data System (ADS)

The results of new studies of creating protective oxide coatings based on Al2O3 (Si, Mn) and deposited onto aluminum alloys using electrolyte-plasma oxidation are presented. An analysis is performed by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction, Rutherford backscattering of 4He+ and protons, nanoindentation, scratching, friction coefficient measurements, and acoustic emission measurements. The results demonstrate that the deposited coatings have a high quality, hardness, and wear resistance and a low thermal diffusivity. Apart from Al2O3, the coatings are found to have Si, Mn, C, and Ca. The stoichiometry of the coatings is determined. The density and hardness of the coatings are close to those of ?-Al2O3 in the coating on an Al-Cu (D-16) substrate, and these values of the coating on an Al-Mg (S006) are lower by a factor of 1.5.

Pogrebnyak, A. D.; Kylyshkanov, M. K.; Tyurin, Yu. N.; Kaverina, A. Sh.; Yakushchenko, I. V.; Borisenko, A. A.; Postol'ny, B. A.; Kulik, I. A.

2012-06-01

450

1300 K compressive properties of a reaction milled NiAl-AlN composites  

NASA Technical Reports Server (NTRS)

When B2 crystal-structure nickel aluminide is subjected to high-intensity mechanical ball milling in a liquid nitrogen bath, or 'cryomilling', an NiAl composite is obtained which contains about 10 vol pct AlN particles. This composition arises from the incorporation of N during cryomilling; during subsequent thermomechanical processing, the N reacts with Al. While compressive testing of extruded or isostatically pressed specimens at 1300 K indicated that strength at relatively fast strain rates is slightly dependent on consolidation method, slower strain rates indicate no clear dependency on densification technique: four different consolidation methods were found to yield similar creep strengths. The creep properties of NiAl-AlN are similar to those of the single-crystal Ni-base superalloy NASAIR 100.

Whittenberger, J. Daniel; Arzt, Eduard; Luton, Michael J.

1990-01-01

451

Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction: gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3)  

NASA Technical Reports Server (NTRS)

The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.

Copeland, Evan

2008-01-01

452

Formation of gamma'-Ni3Al via the Peritectoid Reaction: gamma plus beta (+Al2O3) equals gamma'(+Al2O3)  

NASA Technical Reports Server (NTRS)

The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma'-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3) = gamma + beta (+ Al2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%Al (at an unknown oxygen content). The {gamma + beta + Al2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3Al forms via the peritectiod, gamma + beta (+ Al2O3) = gamma'(+ Al2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3Al phase field.

Copland, Evan

2008-01-01

453

Influence of reaction with XeF2 on surface adhesion of Al and Al2O3 surfaces  

Microsoft Academic Search

The change in surface adhesion after fluorination of Al and Al2O3 surfaces using XeF2 was investigated with atomic force microscopy. The chemical interaction between XeF2 and Al and Al2O3 surfaces was studied by in situ x-ray photoelectron spectroscopy. Fresh Al and Al2O3 surfaces were obtained by etching top silicon layers of Si?Al and Si?Al2O3 with XeF2. The surface adhesion and

Tianfu Zhang; Jeong Y. Park; Wenyu Huang; Gabor A. Somorjai

2008-01-01

454

Influence of reaction with XeF2 on surface adhesion of Al and Al2O3 surfaces  

Microsoft Academic Search

The change in surface adhesion after fluorination of Al and Al2O3 surfaces using XeF2 was investigated with atomic force microscopy. The chemical interaction between XeF2 and Al and Al2O3 surfaces was studied by in situ x-ray photoelectron spectroscopy. Fresh Al and Al2O3 surfaces were obtained by etching top silicon layers of Si\\/Al and Si\\/Al2O3 with XeF2. The surface adhesion and

Tianfu Zhang; Jeong Y. Park; Wenyu Huang; Gabor A. Somorjai

2008-01-01

455

Wear characteristics of Al-AlN composites produced in-situ by nitrogenation  

NASA Astrophysics Data System (ADS)

In the present scenario most of the parts used in automobile and aerospace industries are made of composites. Aluminium metal has a very high strength to weight ratio. Al-AlN metal matrix composites have excellent mechanical properties like good wear resistance, high hardness and high strength to weight ratio which are obtained from low density of aluminium and high hardness and wear resistance of AlN. Therefore, use of Al-AlN MMC leads to advantages in automobile industries as it reduces fuel consumption and gives better structural strength. The composites can be produced ex-situ by introducing AlN as reinforcement into the metal matrix and in- situ by nitrogenation process. In the present process Al-AlN composites were fabricated by treating molten aluminium with a mixture of CaO and NH4Cl and held at temperature range at 750-930°C and then cast into a metal mould. Addition of CaO to NH4Cl is found to have a more pronounced effect as a nitrogenation agent in comparison with NH4Cl in the molten aluminium in the temperature range of 700- 1000°C. Castings of aluminium and Al-AlN composites were prepared by mixing different ratios of aluminium and NH4Cl, at different casting temperatures and holding time. Wear resistance and hardness of the samples were determined, and microstructure studies were carried out. The composite formed using higher amount of NH4Cl had higher hardness and wear resistance.

Pradhan, S.; Jena, S. K.; Patnaik, S. C.; Swain, P. K.; Majhi, J.

2015-02-01

456

AL ASK A SALMON alaska Salmon  

E-print Network

189 AL ASK A SALMON UNIT 13 alaska Salmon INTRODUCTION Pacific salmon have played an important and pivotal role in the history of Alaska. Salmon, along with mining, timber, and furs, were the keystone now, the abundant salmon resources of this region continue to shape much of the con- temporary lives

457

U-ALS: A Ubiquitous Learning Environment  

ERIC Educational Resources Information Center

The diffusion of the use of the learning virtual environments presents a great potential for the development of an application which meet the necessities in the education area. In view of the importance of a more dynamic application and that can adapt itself continuously to the students' necessities, the "U-ALS" (Ubiquitous Adapted Learning…

Piovesan, Sandra Dutra; Passerino, Liliana Maria; Medina, Roseclea Duarte

2012-01-01

458

Microbial Bioreactor Development in the ALS NSCORT  

Microsoft Academic Search

The NASA Specialized Center of Research and Training in Advanced Life Support (the ALS NSCORT), a partnership of Alabama A & M, Howard, and Purdue Universities, was established by NASA in 2002 to develop technologies that will reduce the Equivalent System Mass (ESM) of regenerative processes within future space life-support systems. A key focus area of NSCORT research has been

Cary Mitchell; Dawn Whitaker; M. Katherine Banks; Albert J. Heber; Ronald F. Turco; Loring F. Nies; James E. Alleman; Sybil E. Sharvelle; Congna Li; Megan Heller

2008-01-01

459

Bierman {ital et al.}Reply:  

SciTech Connect

reply to the Comment by C.H.Dasso et al., Phys. Rev. Lett. 78,XXX(1997). A Reply to the Comment by C.H. Dasso and J. Fern{acute a}ndez-Niello. {copyright} {ital 1997} {ital The American Physical Society}

Bierman, J.D.; Chan, P.; Liang, J.F.; Kelly, M.P.; Sonzogni, A.A.; Vandenbosch, R. [Nuclear Physics Laboratory University of Washington Seattle, Washington 98195 (United States)] [Nuclear Physics Laboratory University of Washington Seattle, Washington 98195 (United States)

1997-05-01

460

(12) United States Patent Grier et al.  

E-print Network

(12) United States Patent Grier et al. US008502132B2 US 8,502,132 B2 Aug. 6, 2013 (10) Patent N0.: (45) Date of Patent: (54) (75) (73) (*) (21) (22) (65) (62) (60) (51) (52) MANIPULATION OF OBJECTS) Assignee: New York University, NeW York, NY (Us) Notice: Subject to any disclaimer, the term ofthis patent

Grier, David

461

(12) United States Patent Vertes et al.  

E-print Network

(12) United States Patent Vertes et al. (54) LASERABLATION ELECTROSPRAY IONIZATION (LAESI) ( *) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days. lbis patent is subject to a terminal dis- claimer. (21) Appl. No.: 131271,435 Oct. 12, 2011

Vertes, Akos

462

(12) United States Patent Geohegan et al.  

E-print Network

(12) United States Patent Geohegan et al. US008540542B2 US 8,540,542 B2 Sep. 24, 2013 (10) Patent N0.: (45) Date of Patent: (54) TRANSPARENT CONDUCTIVE NANO-COMPOSITES (75) Inventors: David Bruce Research Foundation, Knoxville, TN (US) Notice: Subject to any disclaimer, the term ofthis patent

Geohegan, David B.

463

COMUNICATO STAMPA Tiroide, visite gratuite al Ruggi  

E-print Network

effettuando visite gratuite con ecografia della tiroide presso il Day Service di Patologia Tiroidea, diretto:00 presso il Day Service di Patologia Tiroidea al 4° piano del corpo C-D dell'AOU S. Giovanni di Dio e Ruggi

Costagliola, Gennaro

464

Luminescence in Li? Al ? (PO?)? :Eu(2+).  

PubMed

A series of efficient Li? Al ? (PO?)? :Eu(2+) novel phosphors were synthesized by the facile combustion method. The effects of dopant on the luminescence behavior of Li? Al ? (PO?)? phosphor were also investigated. The phosphors were characterized by X-ray diffraction, field emission scanning electron microscope and photoluminescence techniques. The result shows that all samples can be excited efficiently by near-ultraviolet excitation under 310?nm. The emission was observed for Li? Al ? (PO?)? :Eu(2+) phosphor at 425?nm, which corresponded to the d ? f transition. The concentration quenching of Eu(2+) was observed in Li? Al ? (PO?)? :Eu(2+) when the Eu concentration was at 0.5?mol%. The prepared powders exhibited intense blue emission at the 425?nm owing to the Eu(2+) ion by Hg-free excitation at 310?nm (i.e., solid-state lighting excitation). Consequently, the availability of such a phosphor will significantly help in the development of blue-emitting solid-state lighting applications. PMID:23019178

Shinde, K N; Park, K

2013-01-01

465

AgriculturAl 2013 Annual Report  

E-print Network

Dean of Agriculture and Natural Resources Rutgers, The State University of New Jersey ExecutiveNew Jersey AgriculturAl experimeNt stAtioN 2013 Annual Report #12;To enhance the vitality, health, sustainability, and overall quality of life in New Jersey by developing and delivering practical, effective

Goodman, Robert M.

466

Correction to Rothermund et al. (2005)  

ERIC Educational Resources Information Center

This article reports an error in the article "Retrieval of Incidental Stimulus-Response Associations as a Source of Negative Priming" by Rothermund et al. ("Journal of Experimental Psychology: Learning, Memory, and Cognition," Vol 31(3) May 2005, 482-495). Table 1 (p. 484) was incorrectly typeset. The correct layout is provided. (The following…

Rothermund, Klaus; Wentura, Dirk; De Houwer, Jan

2005-01-01

467

(12) United States Patent Colace et al.  

E-print Network

(12) United States Patent Colace et al. (54) (75) (73) SYSTEM AND METHOD ALLOWING ADVERTISERS, Toluca Lake, CA (US); Scott W. Snell, Hollywood, CA (US); Jeremy Daw, Alta Lorna, CA (US); Dominic Dough-Ming Cheung, South Pasadena, CA (US); Benjamin James Watkins, Torrance, CA (US); Thomas A. Soulanille

Shamos, Michael I.

468

4, 309333, 2008 T. Arsouze et al.  

E-print Network

CPD 4, 309­333, 2008 Neodymium modelling T. Arsouze et al. Title Page Abstract Introduction of the Atlantic thermohaline circulation on neodymium isotopic composition at the Last Glacial Maximum Publications on behalf of the European Geosciences Union. 309 #12;CPD 4, 309­333, 2008 Neodymium modelling T

Paris-Sud XI, Université de

469

Das Faktorisierungsrepr asentationsproblem als Basis kryptographischer Protokolle  

E-print Network

Wolfgang Goethe-Universit at in Frankfurt am Main | von Roger Fischlin aus O#11;enbach am Main | Frankfurt am Main 2002 D F 1 #12; ii Vom Fachbereich Mathematik der Johann Wolfgang Goethe-Universit at als Mitarbeit von 1998 bis 2001 in der Gruppe von Prof. Dr.Schnorr am Fachbereich Ma- thematik der J.W.Goethe

470

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

A ternary magnetic refrigerant material comprising (Dy.sub.1-x Er.sub.x)Al.sub.2 for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant.

Gschneidner, Jr., Karl A. (Ames, IA); Takeya, Hiroyuki (Ibaraki, JP)

1995-07-25

471

(12) United States Patent Vertes et al.  

E-print Network

) PCTFiled: Jan. 26, 2006 (86) PCTNo.: PCT/US2006/002483 § 371 (c)(1), (2), (4) Date: Jul. 20, 2007 (87) PCT Pub. No.: W02006/081240 PCT Pub. Date: Aug. 3, 2006 (65) Prior Publication Data US 2008/0149822 Al lun

Vertes, Akos

472

The Rail Gun Muad Al Khaldi  

E-print Network

The Rail Gun Muad Al Khaldi Department of Electrical Engineering King Fahd University of Petroleum and Minerals Abstract- The rail gun is one of promising ways of launching projectiles. Recently, many. In this project, I am going to investigate the construction of electromagnetic rail guns, the way the function

Masoudi, Husain M.

473

(12) United States Patent Bauer et al.  

E-print Network

Intuit's Quicken InsureMarket Offering Online Auto Policies in 6 States, Dec. 1998, Business Wire(12) United States Patent Bauer et al. (54) APPARATUS FOR INTERNET ON-LINE INSURANCE POLICY SERVICE * 912000 OTHER PUBLICATIONS Pasher, Auto Web site takes off, Mar. 1998, National Underwriter (Propert

Shamos, Michael I.

474

(12) United States Patent Black et al.  

E-print Network

Alamos, New Mexico. After one test explos:ion, two atomic .bombs: were dropped on the Japanese cities of Hiroshima (6 Aug 1945) and Nagasaki (9 _:Aug 1945); the bomb dropped on - .Hiroshima was as. powerful as metric tons of TNT, that on equivalent to 22.000 metrie tOI"ll The USSR first detbnated al'l atomic 1949

Shamos, Michael I.

475

Eigennutz als Triebfeder des Wohlstands: Die \\  

Microsoft Academic Search

Die empirische Prüfung theoretischer Forschungsergebnisse wirft in der Ökonomie - wie bei jeder Sozialwissenschaft - Probleme auf. Anders als in den Naturwissenschaften können volkswirtschaftliche Problemstellungen kaum in Labors nachgestellt werden. Seit einigen Jahren nutzen Ökonomen allerdings die Erfahrungen der Psychologie mit stilisierten Experimenten, um zumindest ihre grundlegenden Verhaltenshypothesen testen zu können. Dieser Beitrag stellt ein einfaches Hörsaal-Experiment vor, das Adam

Roland Kirstein; Dieter Schmidtchen

2002-01-01

476

Clinical trials in ALS: an overview.  

PubMed

Clinical trials in amyotrophic lateral sclerosis (ALS) have been conducted for over half a century now and have incorporated a wide variety of drugs. Most of these trials have had negative results and a cure remains elusive. The explosion in our understanding of molecular biology and parallel developments in clinical epidemiology have opened up a vast number of novel therapeutic strategies. However, advances in statistical analysis, computing, and global communications have also put greater pressure on scientific investigators to improve the design and implementation of clinical trials so that they permit rigorous testing of hypotheses within a solid ethical framework. This article documents the first published trial for all drugs tried clinically in the treatment of ALS, focusing in more detail on the large, multicenter trials of recent years, namely those involving riluzole, ciliary neurotrophic factor, insulin-like growth factor-I, brain-derived neurotrophic factor, and SR57746A. The problems in the design of trials in ALS are discussed, including the selection of end points and surrogate markers of disease progression, and the major parameters in ALS assessment are reviewed. PMID:11442325

Turner, M R; Parton, M J; Leigh, P N

2001-06-01

477

(12) United States Patent Vertes et al.  

E-print Network

(12) United States Patent Vertes et al. (54) NANOPHOTONIC PRODUCTION, MODULATION AND SWITCHING a quasi-periodic antenna array with ion yields that show pro- found dependence on the plane oflaser light polarization and the angle of incidence. By providing photonic ion sources, this enables enhanced control

Vertes, Akos

478

Schler et al 2001 Mycol Arbuscular mycorrhiza  

E-print Network

vulgaris colonized by arbuscular mycorrhizal fungi vesicle arbuscules (c) D. Redecker 10µm #12;Auxilary. Redecker, K. Wex10µm #12;SEM of arbuscles From Mycorrhizal Symbiosis #12;Devonian Fossil Modern Glomales Remy, Taylor et al. 1994 #12;From Gallaud 1905Arum type Paris type #12;AM Hyphae From Mycorrhizal

California at Berkeley, University of

479

Joint SSRTNet/ALS-MES Workshop report  

SciTech Connect

This joint workshop brought together experimentalists and theorists interested in synchrotron radiation and highlighted subjects relevant to molecular environmental science (MES). The strong mutual interest between the participants resulted in joint sessions on the first day, followed by more specialized parallel sessions on the second day. Held in conjunction with the Advanced Light Source (ALS) Users' Association Annual Meeting at the Lawrence Berkeley National Laboratory (Berkeley Lab), the Synchrotron Radiation Research Theory Network (SRRTNet) workshop was co-organized by Michel Van Hove (Berkeley Lab and University of California, Davis) and Andrew Canning (Berkeley Lab), while David Shuh (Berkeley Lab) organized the ALS-MES workshop. SRRTNet is a global network that promotes the interaction of theory and experiment (http://www.cse.clrc.ac.uk/Activity/SRRTnet). The ALS-MES project is constructing Beamline 11.0.2.1-2, a new soft x-ray beamline for MES investigations at photon energies from 75 eV to 2 keV, to provide photons for wet spectroscopy end stations and an upgraded scanning transmission x-ray microscope (STXM). The ALS-MES beamline and end stations will be available for users in the late fall of 2002.

Shuh, David; Van Hove, Michel

2001-11-30

480

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

A ternary magnetic refrigerant material comprising (Dy{sub 1{minus}x}Er{sub x})Al{sub 2} for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant. 29 figs.

Gschneidner, K.A. Jr.; Takeya, Hiroyuki

1995-07-25