scholarly journals Origins of a Low-Sulfur Superalloy Al2O3 Scale Adhesion Map

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 60
Author(s):  
James Smialek
Keyword(s):  
Sulfur Content ◽  
Cyclic Oxidation ◽  
Reactive Element ◽  
Al2o3 Scale ◽  
Sulfur Segregation ◽  
Scale Adhesion ◽  
2Nd Generation ◽  
No Weight Loss ◽  
Transitional Behavior ◽  
Low Sulfur

Low-sulfur single-crystal Ni-base superalloys have demonstrated excellent cyclic oxidation resistance due to improved Al2O3 scale adhesion. This derives from preventing deleterious interfacial sulfur segregation that occurs at common ppm levels of S impurity. Multiple hydrogen-annealing desulfurization treatments were employed to produce a continuum of levels demonstrating this oxidative transition, using 1 h cyclic oxidation at 1100 °C for 500 h to 1000 h. The sulfur content was determined by glow discharge mass spectrometry. The complete gravimetric database of 25 samples is revealed and correlated with sulfur content. Maximum adhesion (i.e., no weight loss) was achieved at ≤ 0.3 ppmw S, significant spallation (20–30 mg/cm2) above 2 ppmw, with transitional behavior between 0.3 and 2 ppmw S. A map suggested that adhesion was enabled when the total sulfur reservoir was less than one S atom per Ni interface atom. Equilibrium models further suggest that segregation may be minimized (~1% at 0.2 ppmw bulk), regardless of section thickness. 1st order adhesion effects have thus been demonstrated for PWA 1480 having no Y, Zr, or Hf reactive element dopants and no possibility of confounding reactive element effects. The results are compared with 2nd generation PWA 1484, Rene’N5, N6, and CMSX-4® SLS, all having Hf dopants.

Microstructural and high-temperature cyclic oxidation response of NiCoCrAlY coatings with and without SiC + ZrB2 reactive-element dispenser

2021 ◽  
pp. 109617
Author(s):  
Gabriel Israel Vásquez Hernández ◽  
Marco Aurelio González Albarrán ◽  
Eduardo Rodríguez de Anda ◽  
Juan Carlos Díaz Guillen ◽  
Omar Jiménez Alemán ◽  
...  
Keyword(s):  
High Temperature ◽  
Cyclic Oxidation ◽  
Reactive Element

Investigation of the qualities of some promising oils of the Absheron oil and gas region

2021 ◽  
Vol 02 ◽  
pp. 22-26
Author(s):  
Yu.A. Abdulayeva ◽  
◽  
N.H. Alekperova ◽  
S.B. Logmanova ◽  
N.F. Kafarova ◽  
...  
Keyword(s):  
Sulfur Content ◽  
Oil And Gas ◽  
Viscosity Index ◽  
Hydrocarbon Composition ◽  
High Viscosity ◽  
Group I ◽  
Oil Fractions ◽  
Low Sulfur Content ◽  
Selective Refining ◽  
Low Sulfur

The article presents the characteristics of characteristic oils of the Apsheron oil and gas region, as well as the hydrocarbon composition of light and oil fractions. Oils of the Apsheron oil and gas region in terms of light fractions, sulfur content, and density are comparable to marketing grades of oils. The standards for prices are: graded crude oil WTI, Light Sweet, Brent, and Russian oils Sokol, Urals, Siberian Light are approaching them. We have studied in detail the yields and hydrocarbon composition of light and oil fractions of oils from the Apsheron oil and gas region. To obtain oils with a high viscosity index, studies were carried out to change the structure of oil fractions using hydrogen using the example of oil fractions of Azeri oil. Due to the significant content of aromatic hydrocarbons, schemes for the processing of oil fractions have been developed, including selective purification of distillates, dewaxing (except for Guneshli oil), as well as hydrocatalytic treatment in a severe mode in the presence of industrial Russian catalysts. As a result, it was possible to obtain API group I oils, according to the viscosity classification corresponding to SAE 20 and SAE 30. Thus, a study of the qualities and hydrocarbon composition of oils from the Absheron oil and gas region showed that these oils are characterized by a high content of light fractions, low density, and low sulfur content. According to these indicators, these oils correspond to the marker oils. In order to obtain base oils with a viscosity index of ≥90 and an aromatic hydrocarbon content of ≥10, a traditional refining method was used: selective refining, dewaxing, and severe hydrotreating.

Cyclic-Oxidation of RexOy-Modified Aluminide Coating

2012 ◽  
Vol 557-559 ◽  
pp. 1721-1726
Author(s):  
Yong Dong Wang ◽  
Yue Bo Zhou
Keyword(s):  
Composite Film ◽  
Cyclic Oxidation ◽  
Aluminide Coating ◽  
Pack Cementation ◽  
Reactive Element ◽  
Aluminide Coatings ◽  
Oxidation In Air

Reactive reactive element oxide RexOy (Re=Ce, Y)-modified aluminide coatings were developed by aluminizing the as-codeposited Ni-RexOy composite film using pack cementation method at 1100°C for 4 h. By comparison, aluminizing was also performed with the same condition on an as-deposited Ni film without RexOy particles. SEM/EDAX and TEM results indicated that the co-deposited CeO2 or Y2O3 particls were homogeneously dispersed in the finer-grain nanocrystalline Ni grains. The cyclic oxidation in air at 900°C indicated that the RexOy -modified aluminide coatings were profoundly spallation resistance as compared to the RexOy -free coatings due to the formation of a continuous adherent α-Al2O3 scale.

Evaluation of the thermal properties of diesel oil with low sulfur content

2017 ◽  
Vol 131 (1) ◽  
pp. 697-704 ◽  
Author(s):  
Camila G. D. Peixoto ◽  
Valter J. Fernandes ◽  
Ana C. F. Coriolano ◽  
Renkel R. Araujo ◽  
Glauber J. T. Fernandes ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Sulfur Content ◽  
Diesel Oil ◽  
Low Sulfur Content ◽  
Low Sulfur

Interfacial Segregation in Oxide Scales on Nicrai-Based Alloys

1997 ◽  
Vol 3 (S2) ◽  
pp. 785-786
Author(s):  
K. Prüβner ◽  
K. B. Alexander ◽  
B. A. Pint ◽  
P. F. Tortorelli ◽  
I. G. Wright
Keyword(s):  
Cyclic Oxidation ◽  
Oxidation Behaviour ◽  
Reactive Elements ◽  
Oxide Scales ◽  
Protective Oxide ◽  
Form Complex ◽  
Scale Adhesion ◽  
Alumina Formers ◽  
Interfacial Segregation ◽  
Nicral Alloys

Previous studies addressing the segregation of reactive elements in protective oxide scales and their beneficial effect on scale adhesion have primarily concentrated on primary alumina-formers (e.g. β-NiAl + FeCrAl).In our study the oxidation behaviour of three NiCrAl alloys, which form complex scales was studied in air at 1423 K and at 1473 K, both in isothermal (100 h) and in cyclic oxidation (100 x lh). The composition (in at.-%) of these alloys is the following: General Electric alloy René N5 (64.9 Ni, 7.8 Cr, 13.9 Al, 0.1 Fe, 2.1 Ta, 0.05 Hf, 1.6 W, 1.0 Re, 0.15 Si, 7.3 Co, 0.9 Mo, 0.003 Y, 0.003 Zr, 4 ppm S, 0.25 C), Ni-7Cr-6.5Al+Y (80.1 Ni, 7.2 Cr, 12.5 Al, 0.01 Fe, 0.14 Si, 0.012 Y, 18 ppm S, 0.05 C) and Ni-10Cr-10Al+Y (71.2 Ni, 9.9 Cr, 18.8 Al, 0.01 Fe, 0.02 Si, 0.041 Y, 16 ppm S, 0.04 C).

Effect of sulfur removal on Al2O3 scale adhesion

1991 ◽  
Vol 22 (3) ◽  
pp. 739-752 ◽  
Author(s):  
James L. Smialek
Keyword(s):  
Sulfur Removal ◽  
Al2o3 Scale ◽  
Scale Adhesion

The Torsional Properties of Normal and Sulfur-Enriched Wool Fibers

1969 ◽  
Vol 39 (3) ◽  
pp. 261-266 ◽  
Author(s):  
L. D. Armstrong ◽  
M. Feughelman
Keyword(s):  
Mechanical Properties ◽  
Sulfur Content ◽  
Distilled Water ◽  
Constant Degree ◽  
Wool Fibers ◽  
The Difference ◽  
Decreasing Ph ◽  
Low Sulfur Content ◽  
Low Sulfur ◽  
Torsional Properties

The mechanical properties in torsion of single wool fibers of biologically produced high- and low-sulfur content have been studied to determine the effects on torsional behavior. The modulus of rigidity and the torsional relaxation, i.e., the decay in torque with time at a constant degree of twist, were determined in fibers tested in glycerol (~0% RH), distilled water, and aqueous solutions of HCl at pH 0.8, 1.8, and 2.9. The sulfur content had no significant effect on the modulus of ridigidy or on the magnitude of the torsional relaxation of dry fibers. Again, for fibers tested in distilled water, no significant effect of sulfur content on the modulus of rigidity was observed, but the percent decay in torque was measurably affected. The decay in torque in 1 hr for fibers of normal wool amounted to 23% of the initial torque and that for fibers of sulfur-enriched wool amounted to 15%. This difference in torsional relaxation behavior of wet fibers of the two wools was not thought to be due to the difference in sulfur content but may partly be linked with the aspartic acid content of the two wools. The modulus of rigidity and the torsional relaxation of fibers in aqueous HCl decreased with decreasing pH to as little as one third of the values obtained in distilled water, presumably due to the breaking of salt links, the decrease being greater for the sulfur-enriched wools.

scholarly journals Compliance and port air quality features with respect to ship fuel switching regulation: a field observation campaign, SEISO-Bohai

2019 ◽  
Vol 19 (7) ◽  
pp. 4899-4916 ◽  
Author(s):  
Yanni Zhang ◽  
Fanyuan Deng ◽  
Hanyang Man ◽  
Mingliang Fu ◽  
Zhaofeng Lv ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Sulfur Content ◽  
Ambient Air ◽  
Ship Emissions ◽  
Study Region ◽  
Fuel Switching ◽  
The Mean ◽  
Hourly Concentration ◽  
Low Sulfur

Abstract. Since 1 January 2017, ships berthed at the core ports of three designated “domestic emission control areas” (DECAs) in China should be using fuel with a sulfur content less than or equal to 0.5 %. In order to evaluate the impacts of fuel switching, a measurement campaign (SEISO-Bohai) was conducted from 28 December 2016 to 15 January 2017 at Jingtang Harbor, an area within the seventh busiest port in the world. This campaign included meteorological monitoring, pollutant monitoring, aerosol sampling and fuel sampling. During the campaign, 16 ship plumes were captured by the on-shore measurement site, and 4 plumes indicated the usage of high-SF (SF refers to the sulfur content of marine fuels). The average reduction of the mean ΔNOx∕ΔSO2 ratio from high-sulfur plumes (3.26) before 1 January to low-sulfur plumes (12.97) after 1 January shows a direct SO2 emission reduction of 75 %, consistent with the sulfur content reduction (79 %). The average concentrations of PM2.5 (particulate matter with a diameter less than 2.5 µm), NOx, SO2, O3 and CO during campaign were 147.85 µg m−3, 146.93, 21.91, 29.68 ppb and 2.21 ppm, respectively, among which NOx reached a maximum hourly concentration of 692.6 ppb, and SO2 reached a maximum hourly concentration of 165.5 ppb. The mean concentrations of carbonaceous and dominant ionic species in particles were 6.52 (EC – elemental carbon), 23.10 (OC – organic carbon), 22.04 (SO42-), 25.95 (NO3-) and 13.55 (NH4+) µg m−3. Although the carbonaceous species in particles were not significantly affected by fuel switching, the gas and particle pollutants in the ambient air exhibited clear and effective improvements due to the implementation of low-sulfur fuel. Comparison with the prevailing atmospheric conditions and a wind map of SO2 variation concluded a prompt SO2 reduction of 70 % in ambient air after fuel switching. Given the high humidity at the study site, this SO2 reduction will abate the concentration of secondary aerosols and improve the acidity of particulate matter. Based on the enrichment factors of elements in PM2.5, vanadium was identified as a marker of residual fuel ship emissions, decreasing significantly by 97.1 % from 309.9 ng m−3 before fuel switching to 9.1 ng m−3 after regulation, which indicated a crucial improvement due to the implementation of low-sulfur fuels. Ship emissions were proven to be significantly influential both directly and indirectly on the port environment and the coastal areas around Bohai Bay, where the population density reaches over 650 people per square kilometer. The results from this study report the positive impact of fuel switching on the air quality in the study region and indicate a new method for identifying the ship fuel type used by vessels in the area.

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