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  Subjects -> CHEMISTRY (Total: 920 journals)
    - ANALYTICAL CHEMISTRY (56 journals)
    - CHEMISTRY (655 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (27 journals)
    - INORGANIC CHEMISTRY (43 journals)
    - ORGANIC CHEMISTRY (47 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (655 journals)            First | 1 2 3 4 | Last

Showing 401 - 600 of 735 Journals sorted alphabetically
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 3)
Journal of Raman Spectroscopy     Hybrid Journal   (Followers: 17)
Journal of Research Updates in Polymer Science     Hybrid Journal   (Followers: 3)
Journal of Saudi Chemical Society     Open Access  
Journal of Solid State Chemistry     Hybrid Journal   (Followers: 14)
Journal of Solution Chemistry     Hybrid Journal   (Followers: 2)
Journal of Structural Chemistry     Hybrid Journal   (Followers: 1)
Journal of Sulfur Chemistry     Hybrid Journal   (Followers: 3)
Journal of Supercritical Fluids     Hybrid Journal   (Followers: 4)
Journal of Superhard Materials     Hybrid Journal   (Followers: 1)
Journal of Surface Science and Technology     Hybrid Journal  
Journal of Surfactants and Detergents     Hybrid Journal   (Followers: 3)
Journal of Taibah University for Science     Open Access   (Followers: 1)
Journal of the American Chemical Society     Hybrid Journal   (Followers: 375)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 31)
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (Followers: 3)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Chilean Chemical Society     Open Access   (Followers: 2)
Journal of the Iranian Chemical Society     Hybrid Journal  
Journal of the Korean Society for Applied Biological Chemistry     Hybrid Journal   (Followers: 1)
Journal of the Mexican Chemical Society     Open Access   (Followers: 2)
Journal of the Serbian Chemical Society     Open Access  
Journal of the Turkish Chemical Society, Section A : Chemistry     Open Access  
Journal of Theoretical and Computational Chemistry     Hybrid Journal   (Followers: 10)
JPC - Journal of Planar Chromatography - Modern TLC     Full-text available via subscription   (Followers: 2)
Jurnal Inovasi Pendidikan Kimia     Open Access   (Followers: 5)
Jurnal Katalisator     Open Access  
Jurnal Kimia (Journal of Chemistry)     Open Access  
Jurnal Kimia Riset     Open Access  
Jurnal Penelitian Sains (JPS)     Open Access  
Karadeniz Chemical Science and Technology     Open Access  
Karbala International Journal of Modern Science     Open Access   (Followers: 3)
Kinetics and Catalysis     Hybrid Journal   (Followers: 5)
Konfigurasi : Jurnal Pendidikan Kimia dan Terapan     Open Access  
Korea-Australia Rheology Journal     Hybrid Journal  
Langmuir     Hybrid Journal   (Followers: 64)
Latvian Journal of Chemistry     Open Access   (Followers: 1)
Lebensmittelchemie     Hybrid Journal   (Followers: 1)
Lipid Insights     Open Access  
Luminescence     Hybrid Journal   (Followers: 5)
Macromolecular Materials & Engineering     Hybrid Journal   (Followers: 5)
Macromolecular Rapid Communications     Hybrid Journal   (Followers: 10)
Macromolecular Research     Hybrid Journal   (Followers: 2)
Macromolecular Symposia     Hybrid Journal   (Followers: 3)
Macromolecular Theory and Simulations     Hybrid Journal   (Followers: 2)
Macromolecules     Hybrid Journal   (Followers: 51)
Maghrebian Journal of Pure and Applied Science     Full-text available via subscription  
Magnetic Resonance in Chemistry     Hybrid Journal   (Followers: 10)
Magnetochemistry     Open Access  
Marine Chemistry     Hybrid Journal   (Followers: 7)
Marine Drugs     Open Access   (Followers: 3)
MATEC Web of Conferences     Open Access   (Followers: 5)
Materials Characterization     Hybrid Journal   (Followers: 34)
Materials Chemistry Frontiers     Full-text available via subscription  
Materials Horizons     Full-text available via subscription   (Followers: 3)
Materials Research Bulletin     Hybrid Journal   (Followers: 28)
Materials Science Monographs     Full-text available via subscription   (Followers: 3)
Materials Science-Poland     Open Access   (Followers: 1)
Materials Sciences and Applications     Open Access   (Followers: 3)
MedChemComm     Full-text available via subscription   (Followers: 6)
Medicinal Chemistry Research     Hybrid Journal   (Followers: 12)
Mediterranean Journal of Chemistry     Open Access  
Metallography, Microstructure, and Analysis     Hybrid Journal   (Followers: 2)
Metallomics     Full-text available via subscription  
Micro and Nano Systems Letters     Open Access   (Followers: 6)
Microchimica Acta     Hybrid Journal   (Followers: 2)
Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 10)
Modern Chemistry & Applications     Open Access   (Followers: 1)
Modern Research in Catalysis     Open Access   (Followers: 1)
Molbank     Open Access   (Followers: 1)
Molecular Astrophysics     Full-text available via subscription  
Molecules     Open Access   (Followers: 7)
Molecules and Cells     Hybrid Journal   (Followers: 1)
Monatshefte für Chemie - Chemical Monthly     Hybrid Journal   (Followers: 4)
Mongolian Journal of Chemistry     Open Access  
Moroccan Journal of Chemistry     Open Access  
Moroccan Journal of Heterocyclic Chemistry     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
MRS Bulletin     Full-text available via subscription   (Followers: 4)
MRS Online Proceedings     Full-text available via subscription   (Followers: 1)
Nachrichten aus der Chemie     Hybrid Journal   (Followers: 17)
Nano Convergence     Open Access   (Followers: 1)
Nano Reviews & Experiments     Open Access   (Followers: 14)
Nanochemistry Research     Open Access  
Nanocontainers     Open Access   (Followers: 1)
Nanomaterials and the Environment     Open Access   (Followers: 1)
Nanoscale     Full-text available via subscription   (Followers: 20)
Nanoscale Advances     Open Access   (Followers: 1)
Nanoscale Research Letters     Open Access   (Followers: 9)
Nanoscience and Nanotechnology Letters     Full-text available via subscription   (Followers: 22)
Nanospectroscopy     Open Access   (Followers: 2)
Natural Product Reports     Full-text available via subscription   (Followers: 10)
Natural Products Chemistry & Research     Open Access   (Followers: 1)
Natural Products Journal     Hybrid Journal   (Followers: 1)
Natural Science     Open Access   (Followers: 9)
Natural Volatiles & Essential Oils     Open Access  
Nature Chemistry     Full-text available via subscription   (Followers: 93)
Nature Protocols     Full-text available via subscription   (Followers: 70)
Nature Reviews Chemistry     Hybrid Journal   (Followers: 7)
New Journal of Chemistry     Full-text available via subscription   (Followers: 20)
Nitric Oxide     Hybrid Journal  
Nitrogen     Open Access  
Nova Biotechnologica et Chimica     Open Access  
Nukleonika     Open Access   (Followers: 2)
Open Chemistry     Open Access   (Followers: 6)
Open Chemistry Journal     Open Access  
Open Conference Proceedings Journal     Open Access  
Open Journal of Composite Materials     Open Access   (Followers: 18)
Open Journal of Inorganic Non-metallic Materials     Open Access   (Followers: 4)
Open Journal of Medicinal Chemistry     Open Access   (Followers: 5)
Open Journal of Polymer Chemistry     Open Access   (Followers: 13)
Open Journal of Synthesis Theory and Applications     Open Access  
Open Medicinal Chemistry Journal     Open Access  
Orbital - The Electronic Journal of Chemistry     Open Access   (Followers: 3)
Organic & Biomolecular Chemistry     Full-text available via subscription   (Followers: 74)
Organometallics     Hybrid Journal   (Followers: 22)
Organosulfur Chemistry     Full-text available via subscription  
Oxidation of Metals     Hybrid Journal   (Followers: 18)
Peptidomics     Open Access  
Pharmaceuticals     Open Access   (Followers: 6)
Pharmaceutics     Open Access   (Followers: 4)
Phosphorus, Sulfur, and Silicon and the Related Elements     Hybrid Journal   (Followers: 2)
Photochemistry and Photobiology     Hybrid Journal   (Followers: 4)
Physical Sciences Reviews     Hybrid Journal   (Followers: 1)
Physics and Materials Chemistry     Open Access   (Followers: 2)
Phytochemistry     Hybrid Journal   (Followers: 6)
Phytochemistry Letters     Full-text available via subscription   (Followers: 4)
Plasma     Open Access   (Followers: 2)
Plasma Chemistry and Plasma Processing     Hybrid Journal   (Followers: 6)
Polímeros : Ciência e Tecnologia     Open Access  
Polycyclic Aromatic Compounds     Hybrid Journal  
Polyhedron     Hybrid Journal   (Followers: 4)
Polymer Chemistry     Full-text available via subscription   (Followers: 25)
Polymer Degradation and Stability     Hybrid Journal   (Followers: 26)
Polymer Engineering & Science     Hybrid Journal   (Followers: 16)
Polymer Reviews     Hybrid Journal   (Followers: 36)
Polymer Science Series D     Hybrid Journal   (Followers: 4)
Polymer Testing     Hybrid Journal   (Followers: 126)
Polymer-Plastics Technology and Engineering     Hybrid Journal   (Followers: 5)
Polymers     Open Access   (Followers: 18)
Procedia Chemistry     Open Access  
Proceedings in Radiochemistry. A Supplement to Radiochimica Acta     Open Access   (Followers: 1)
Proceedings of the Combustion Institute     Full-text available via subscription   (Followers: 8)
Processes     Open Access  
Progress in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 1)
Progress in Lipid Research     Hybrid Journal   (Followers: 3)
Progress in Organic Coatings     Hybrid Journal   (Followers: 9)
Progress in Polymer Science     Full-text available via subscription   (Followers: 37)
Progress in Reaction Kinetics and Mechanism     Full-text available via subscription   (Followers: 2)
Progress in Solid State Chemistry     Full-text available via subscription   (Followers: 3)
Progress in Surface Science     Full-text available via subscription   (Followers: 4)
Protein Science     Hybrid Journal   (Followers: 46)
Pure and Applied Chemistry     Hybrid Journal   (Followers: 8)
Química Nova     Open Access  
Quimica Viva     Open Access  
Radiochemistry     Hybrid Journal   (Followers: 2)
Rapid Communications in Mass Spectrometry     Hybrid Journal   (Followers: 31)
Reaction Chemistry & Engineering     Hybrid Journal  
Reaction Kinetics, Mechanisms and Catalysis     Hybrid Journal   (Followers: 2)
Recent Advances in Phytochemistry     Full-text available via subscription   (Followers: 3)
Recyclable Catalysis     Open Access   (Followers: 2)
Reports in Theoretical Chemistry     Open Access  
Research and Reports in Medicinal Chemistry     Open Access   (Followers: 3)
Research Journal of Phytochemistry     Open Access   (Followers: 3)
Review Journal of Chemistry     Hybrid Journal  
Reviews in Chemical Engineering     Hybrid Journal   (Followers: 6)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 4)
Reviews of Adhesion and Adhesives     Full-text available via subscription  
Revista CENIC. Ciencias Quimicas     Open Access   (Followers: 2)
Revista Ciências Exatas e Naturais : RECEN     Open Access  
Revista Colombiana de Química     Open Access   (Followers: 1)
Revista Cubana de Química     Open Access  
Revista de Ciencia y Tecnología     Open Access  
Revista de Ciencias     Open Access  
Revista de la Societat Catalana de Química     Open Access  
Revista Debates em Ensino de Química     Open Access  
Revista ION     Open Access  
Revista Química : ciência, tecnologia e sociedade     Open Access  
RHAZES : Green and Applied Chemistry     Open Access  
RSC Advances     Open Access   (Followers: 33)
Rubber Chemistry and Technology     Full-text available via subscription   (Followers: 2)
Russian Chemical Reviews     Full-text available via subscription   (Followers: 4)
Russian Journal of Bioorganic Chemistry     Hybrid Journal   (Followers: 2)
Russian Journal of Coordination Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of General Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of Inorganic Chemistry     Hybrid Journal  
Sainstek : Jurnal Sains dan Teknologi     Open Access  
Science China Chemistry     Hybrid Journal   (Followers: 2)
Sciences & Technologie A : sciences exactes     Open Access  
Scientific Journal of Frontier Chemical Development     Open Access   (Followers: 2)
Scientific Reports     Open Access   (Followers: 73)
Sensors and Actuators B: Chemical     Hybrid Journal   (Followers: 17)
Separation & Purification Reviews     Hybrid Journal   (Followers: 8)
Separation Science and Technology     Hybrid Journal   (Followers: 14)
Separations     Open Access   (Followers: 6)
Silicon Chemistry     Hybrid Journal   (Followers: 2)
Smart Materials Research     Open Access   (Followers: 7)
Soft     Open Access  
Soft Nanoscience Letters     Open Access   (Followers: 2)
Solid State Communications     Hybrid Journal   (Followers: 7)

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Similar Journals
Journal Cover
Oxidation of Metals
Journal Prestige (SJR): 0.655
Citation Impact (citeScore): 1
Number of Followers: 18  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-4889 - ISSN (Online) 0030-770X
Published by Springer-Verlag Homepage  [2351 journals]
  • High-Temperature Oxidation Behavior of a Single-Layer IrAl Intermetallic
           Coating
    • Abstract: In order to improve the high-temperature service property of Ir, a well-bonded single-layer pure IrAl intermetallic coating was prepared on Ir by pack cementation followed by vacuum annealing treatment. The oxidation behavior of the IrAl coating was investigated by cyclic oxidation tests at 1400–2000 °C and compared with that of pure Ir. The results showed that the IrAl coating, although containing many cracks, exhibited excellent oxidation resistance over the whole experimental temperature range. The reasons were deduced to be the in situ formation of Al2O3 and the sintering of the cracks in the IrAl layer. The excellent oxidation protective effect of the single-layer IrAl coating can be ascribed to its stable and unique as-oxidized microstructure, i.e., double-layer structure of Al2O3/Ir′, which showed excellent compatibility and comprehensive property.
      PubDate: 2019-03-14
       
  • Oxidation Behavior of the Skutterudite Material Ce 0.75 Fe 3 CoSb 12
    • Abstract: A thermoelectric generator is a powerful system used to produce electricity by the action of heat. The development of nanostructured thermoelectric materials is widespread with the objective to improve their efficiency. However, if these materials are used at high temperatures under oxidative atmosphere (e.g., in air), they may suffer degradation in service, drastically decreasing their lifespan. This work investigates the oxidation behavior of an innovative skutterudite material made of cerium, iron, cobalt and antimony (Ce0.75Fe3CoSb12) either microstructured or nanostructured. For that purpose, several oxidation experiments are carried out under a flow of synthetic air at 650 K (15 h, 50 h and 100 h). The oxide layers formed on surface are observed, and their characteristics (chemical composition, thickness, structure) are compared to those obtained with microstructured Ce0.75Fe3CoSb12 samples. As a result, it is observed that the nanostructuring of the skutterudite materials slightly slow down the oxidation reactions in air. Consequently, the nanostructured Ce0.75Fe3CoSb12 is established to be a promising thermoelectric material for use in oxidative environments.
      PubDate: 2019-03-14
       
  • High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler
           Applications
    • Abstract: The present study investigates the initial corrosion behaviour of HVAF-sprayed NiCr, NiAl and NiCrAlY coatings in two different environments, O2 + H2O and O2 + H2O + KCl at 600 °C for up to 168 h in order to evaluate the possibility of utilizing such coatings in biomass- and waste-fired boilers. SEM/EDX analysis showed that all coatings displayed a protective behaviour in O2 + H2O. Upon addition of KCl (O2 + H2O + KCl), the corrosion behaviour of the NiCr coating drastically changed as it formed a thick oxide layer and displayed major chlorine diffusion down to the substrate. The NiCrAlY coating displayed a significantly better corrosion resistance with only minor oxide formation. The NiAl coating exhibited a protective behaviour similar to when exposed in the absence of KCl indicating that a thin protective oxide has formed on the coating surface. The performance of the NiAl and NiCrAlY coatings is promising for future studies with long-term exposures in more corrosive environments such as in a biomass- and waste-fired boiler.
      PubDate: 2019-03-14
       
  • Characterization of the Oxide Scale Formed on T12 Water Wall Tube After
           Long-term Service in Supercritical Power Plant
    • Abstract: Oxide scale control is one of the critical maintenance issues in fossil fuel power plant. Hence, the water treatment of the feed water has been changed from all-volatile treatment (AVT) to oxygenated treatment (OT) by added some amount of oxygen in the system to form a stable oxide and minimize the scale growth rate. In this work, the oxide scales formed on T12 water wall tube after one cycle of chemical cleaning treatment under OT condition in a supercritical coal power plant were characterized by using various methods. It was found that the oxide scale formed on the inner surface of the tube had a multi-layer structure with a porous outer layer consisting of Fe3O4 and Cr-rich α-Fe2O3 oxides and a dense inner layer consisting of Cr-rich spinel oxide. A Cr- and Mn-enriched outermost layer was also observed. Cavities, pits, and exfoliation were observed in the oxide scales. The cavities and grain boundaries behaved as the short path of the diffusion of oxygen into the metal. Intergranular oxidation was observed between the inner layer of oxide scale and matrix. The distribution, morphology, and chemical compositional of these oxides were assessed and discussed from a point of view of the suitability of current chemical cleaning solution and procedure which has been used for AVT descaling.
      PubDate: 2019-02-22
       
  • The Effect of HVOF Bond Coating with APS Flash Coating on TBC Performance
    • Abstract: To study the benefit of ~ 50-µm-thick air-plasma-sprayed (APS) ‘flash’ bond coatings, NiCoCrAlYHfSi high-velocity oxygen fuel (HVOF) bond coatings were deposited on alloy 247 disk substrates with APS yttria-stabilized zirconia topcoatings. Using 1-h cycles at 1100 °C in air with 10% H2O and HVOF-only bond coatings as a baseline, APS flash coatings extended the average coating lifetime by > 10% using NiCoCrAlYHfSi and > 70% using NiCoCrAlY powder. Coatings were characterized after 0, 100 and 300 cycles and after failure. Residual stress in the thermally grown alumina scale was mapped every 100 cycles using photo-stimulated luminescence piezospectroscopy. The flash coating created an interlocked metal–alumina layer that appeared to inhibit critical crack formation, and the underlying HVOF layer prevented further internal oxidation and appeared to supply the APS flash coating with Al. The addition of Hf and Y to the flash coating increased internal oxidation and accelerated Al consumption, thereby reducing the benefit of the flash coating.
      PubDate: 2019-02-22
       
  • The Corrosion of an Amorphous Fe 70 C 10 P 10 B 5 Mo 5 Alloy in Various CO
           2 /CO Mixed Gases at 500 °C
    • Abstract: The corrosion behavior of an Fe70C10P10B5Mo5 amorphous ribbon was investigated in various CO2/CO mixed gases within the oxygen partial pressure range 7.2 × 10−24 to 7.2 × 10−22 Pa at 500 °C. In general, the amorphous alloy exhibited exclusive oxidation throughout the study, and its oxidation kinetics followed the parabolic rate law. The parabolic rate constants steadily increased with increasing oxygen pressure, indicating a typical scaling behavior for p-type semiconductivity. The scale formed on the glassy alloy consisted mostly of Fe3O4 and a minor amount of B2O3, and the formation of B2O3 is responsible for the lower scaling rate of the glassy alloy as compared with that of pure Fe.
      PubDate: 2019-02-21
       
  • Influence of Nickel on the Oxidation Resistance at High Temperatures of
           Thin Chromium Coatings
    • Abstract: The oxidation behavior of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) covered with thin sputter-deposited coatings containing chromium and nickel was studied under isothermal and thermal shock conditions. It was determined that coated steels exhibit greater resistance against oxidation than steels with unmodified surfaces. This effect results from the formation of chromium-rich oxides (e.g., Cr2O3, NiCr2O4, MnCr2O4) during oxidation of the surface modified steel. These oxides exhibited better protective properties than the products grown on unmodified steels (namely Fe3O4 and Fe2O3). The entirety of the obtained experimental results confirms the possibility of increasing the scaling resistance of valve steels by using around 1-µm-thick chromium-rich protective Cr–Ni coatings.
      PubDate: 2019-02-12
       
  • Study of SiO 2 on Ni and Ti Silicide After Different Oxidation Techniques
           Investigated by XRR, SEM and Ellipsometry
    • Abstract: Although silicide oxidation was studied 20 years ago, the interest in obtaining a robust process for new applications remains significant today. Indeed, the new architectural development process requires dense and narrow spaces. In this study, attempts were made to bury a silicide layer under a protective silica layer in order to keep the physical and electrical properties of the silicide constant after oxidation. Thus, we first tried to reproduce and study these conditions and, once acquired, aimed to decrease the oxidation temperature in order to meet industrial requirements. Titanium (Ti) and nickel (Ni) were chosen for their metallurgical interest and their integration capability in devices. Four different groups of silicide (TiSi, TiSi2, Ni2Si, NiSi) were targeted by adjusting the temperature. Then, all of the silicides, including one pure Si wafer, were oxidized using dry, wet and plasma techniques. In situ scanning electron microscopy, spectroscopic ellipsometry and X-ray reflectivity measurements were carried out simultaneously before and after oxidation of the silicide to characterize the SiO2 and silicide morphology, thickness and density. We found that after 800 °C dry oxidation, Ti silicide was totally oxidized, which was an unexpected result. But, Ni silicide showed an agglomeration phenomenon after 500 °C and 800 °C dry oxidation. Although, after wet oxidation, it was confirmed that the highest SiO2 thickness formed, the NiSi surface roughness was higher. In the case of plasma oxidation, we obtained a thin layer (≈ 1 nm) of SiO2 on NiSi with an extremely smooth surface.
      PubDate: 2019-02-11
       
  • High-Temperature Corrosion of
           
    • Abstract: Ti–46Al–6Nb–0.5W–0.5Cr–0.3Si–0.1C alloy was corroded at 800–1100 °C for 200 h in N2/0.1%H2S gas to characterize its corrosion behavior in an aggressive H2S-containing environment. The alloy displayed superior corrosion resistance because Ti and Al preferentially reacted with impurity oxygen in the gas to form TiO2 and Al2O3. It corroded primarily by outward diffusion of Ti, Al, W, and Cr in addition to inward transport of sulfur, nitrogen, and oxygen. Scales were adherent and consisted of an outer TiO2 layer, an intermediate Al2O3 layer, and an inner (TiO2, Al2O3)-mixed layer. TiN and Ti2AlN formed at the scale/matrix interface where sulfur, Nb, W, and Cr segregated.
      PubDate: 2019-02-09
       
  • Coordination of Pre-oxidation Time and Temperature for a Better Corrosion
           Resistance to CO 2 at 550 °C
    • Abstract: Influence of pre-oxidation treatment on the oxidation resistance of F91 to CO2 at 550 °C was investigated. The formation of the thin scale of (Fe, Cr)2O3 corundum-type oxides was achieved by pre-oxidation in air, which significantly improved the oxidation resistance. Nodule nucleation and subsequent growth were analyzed and interpreted. Influences of pre-oxidation temperature and time on the oxidation resistance to CO2 are explained by presenting concepts of insufficient pre-oxidation and excess pre-oxidation. A coordination between pre-oxidation temperature and time is proposed.
      PubDate: 2019-02-02
       
  • Oxidation Behavior of Superalloy IN 713 Fabricated by Metal Injection
           Molding
    • Abstract: The oxidation behavior of superalloy IN 713 fabricated by metal injection molding (MIM) was investigated and compared with standard cast material plus hot isostatic pressing (Cast + HIP). The carbon content of MIM alloys varied in the experiments due to the use of different starting powders. At all temperatures and times investigated, weight gain increased strongly with carbon content. Carbon in the alloys was present mainly in the form of carbides. Carbides react with oxygen during oxide scale formation. Microscopy showed that selective oxidation of carbides led to the formation of protrusions and cracks in the oxide layer. In this way, the protective effect of the oxide scale was weakened.
      PubDate: 2019-02-01
       
  • Effect of Zirconium Addition on High-Temperature Cyclic Oxidation of
           Diffusion Chromo-Aluminized Ni-Base Superalloy
    • Abstract: Nimonic 75 alloy was coated with two different types of coatings: chromo-aluminized coating and Zr-doped chromo-aluminized coating. Diffusion coating was carried out by pack cementation process at 1000 °C for 8 h. Cyclic oxidation tests of Nimonic 75 and its coated specimens were conducted at 900, 1000 and 1100 °C in air for a total period of 100 h. During the first 30-h period, 5-h cycle was applied, and during the 40–100-h period, 10-h cycle was applied. The structures of the coated Nimonic 75 alloy before and after high-temperature oxidation were investigated using light microscopy, scanning electron microscopy/energy-dispersive spectroscopy and X-ray diffraction characterization techniques. The results indicated that Zr-doped chromo-aluminide coating is more effective than chromo-aluminide coating in increasing the oxidation resistance of Nimonic 75 alloy. The parabolic oxidation rate constant kp for cyclic oxidation of uncoated , Cr–Al-coated and Zr/Cr–Al-coated alloys are 1.7, 0.77 and 0.61 10−6 mg2 cm−4 s−1 at 900 °C, and 10.08, 5.2 and 3.91 10−6 mg2 cm−4 s−1 at 1000 °C, and 41.27, 26.69 and 18.13 10−6 mg2 cm−4 s−1 at 1100 °C. The improvement in oxidation resistance by zirconium addition to the chromo-aluminized coating is attributed to its effect on achieving better control of interdiffusion fluxes occurring between coating and substrate so as to reduce Kirkendall effect and voids formation, hence enhancing adhesion, in addition to reducing the outward diffusion of aluminum and stabilizing aluminum oxide scale.
      PubDate: 2019-02-01
       
  • Model About the Course of Corrosion Reactions of Austenitic Steels in H 2
           S-, HCl- and CO 2 -Containing Atmospheres at 680 °C
    • Abstract: Material selection for thermal cracking processes of anthropogenic resources is challenging. H2S and HCl are formed, and corrosion occurs at high temperatures. Several steels were investigated in the past. In all cases, corrosion layers were characteristically structured. On top, large chromium sulfide crystals are located, followed by a Cr2O3 layer, followed by a layer enriched in chlorine and nickel. In this paper, we propose a model on the course of the corrosion reactions. By considering the water–gas shift reaction as well as the influence of H2S, the layer formation can be explained. As an example S31400, 240 h corrosion time at 680 °C was chosen.
      PubDate: 2019-02-01
       
  • Impact of Grain Boundary Density on Oxide Scaling Revisited
    • Abstract: A straightforward conceptual tool for discriminating between different oxide scaling processes deviating from the parabolic standard model is formulated. Grain boundary diffusion-controlled oxide scaling is generalized to include lateral grains coarsening. Building on traditional Wagner theory, attenuation of rates of inwards growing oxides owing to the gradual loss of grain boundary density is revisited. Two viable cases are identified. One has the rate of grain boundary density loss to be independent of the rate of oxide growth, while the second case takes the two instantaneous rates to be equal. Simple parabolic–logarithmic and superparabolic–cubic expressions are arrived at for the two cases, respectively. Usefulness is demonstrated by applying the models to published experimental data from 1990 to date. Upon arrival at the superparabolic–cubic behaviour, a generic mathematical form analogous to a ‘spring force’ attenuating the scale growth was identified. ‘Parabolic’, ‘cubic’ and ‘logarithmic’ scaling emerges as limiting cases.
      PubDate: 2019-02-01
       
  • Effect of Thermal Pretreatment and Acid Leaching on the Removal of Boron
           from Metallurgical Grade Silicon
    • Abstract: The present work aims at investigating the impact of thermal pretreatment and acid leaching (HCl–HF) on the boron removal efficiency of metallurgical grade silicon (MG-Si). The impact of various parameters, involving oxidation temperature (700–1200 °C), oxidation time (1–5 h) and acid leaching (4 mol L−1 HCl–3 mol L−1 HF), on the removal of boron from MG-Si was thoroughly explored. It was found that thermal oxidation resulted in an enhanced removal efficiency of boron from MG-Si. By employing MG-Si particles in the range of 75–106 μm in conjunction with acid leaching at 65 °C for 6 h, the boron content was decreased from 19.60 to 14.10 ppmw, offering a removal efficiency of ca. 28%. When the MG-Si powder was subjected to thermal oxidation at 1100 °C for 5 h before leaching, the boron concentration in the purified Si was reduced from 19.60 to 8.90 ppmw, giving an extraction efficiency of 54.59%. An extended characterization study, regarding the microstructure, morphology and chemical composition of both un-treated and treated samples, was conducted to gain insight into the underlying mechanism of boron removal under different conditions.
      PubDate: 2019-02-01
       
  • Microstructure and Oxidation Behavior of Ni–TiO 2 Composite Coating
           at High Temperature
    • Abstract: Ni-based composite coatings are considered to improve the oxidation resistance of stainless steel. In this study, Ni–TiO2 composite coatings were electrodeposited onto the AISI 430 stainless steel. The isothermal oxidation of bare steel and steel with Ni–TiO2 coating was performed at 800 °C for 200 h. Moreover, cyclic oxidation of the coated and bare steel was performed up to 50 cycles. The coating layer and oxide scales were investigated by X-ray diffraction and scanning electron microscopy. All the coated specimens showed good oxidation resistance during the oxidation tests. The TiO2 particles in the coating affected the stability of the protective oxide scale. Furthermore, the coated steel showed a lower oxidation rate compared with the bare steel. It is concluded that TiO2 increases oxidation resistance by blocking the outward diffusion of Cr cations.
      PubDate: 2019-02-01
       
  • Effect of Silicon and Graphite Degeneration on High-Temperature Oxidation
           of Ductile Cast Irons in Open Air
    • Abstract: The use of high silicon ductile irons is increasing as they offer some advantages with respect to conventional pearlitic–ferritic grades such as high elongation at rupture for a given tensile strength value and a fully ferritic matrix. Besides addressing mechanical requirements, some castings must fulfil corrosion and high-temperature oxidation requisites. Two different ductile cast irons with silicon contents of 2.04 and 5.21 wt% were used so as to comparatively study their mechanical properties and high-temperature oxidation responses. The structure of both alloys contains nodular graphite and a fully ferritic matrix. Some samples of the alloy with 5.21 wt% silicon also contain abundant degenerated graphite which was identified as Chunky graphite. Oxidation resistance of both materials was evaluated by exposures to air at 650 °C for 720 h using a tubular furnace. The alloy with 5.21 wt% silicon showed an oxidation resistance about three times higher than the low silicon alloy. Although both alloys showed similar oxidation mechanisms, the oxidation scale formed on the high-silicon alloy stands out for having lower thickness, higher silicon content in the metal/oxide interface and more compact and adherent layers. Samples with Chunky graphite showed a similar evolution to those with graphite nodules, so no negative effect from this graphite degeneration on oxidation process was observed. The analyses performed by XRD revealed the presence of fayalite in the 5.21 wt% Si alloy, which is responsible for the better oxidation resistance. Graphical
      PubDate: 2019-02-01
       
  • Use of Microanalysis to Better Understand the High-Temperature Corrosion
           Behavior of Chromium Exposed to Multi-Oxidant Environments
    • Abstract: The corrosion behavior of metals and alloys at high temperatures in complex multi-oxidant environments is of a great interest for achieving extended service performances and improved operation efficiencies. In this basic study, the scaling reactions of pure chromium in several multi-oxidant gas mixtures were assessed. The environments studied are similar to those that exist in low-NOx burner and coal gasification atmospheres, which are very reducing and favor sulfidation and carburization, together with possible formation of Cr2O3. The effect of sulfur on chromia-scale growth kinetics was also considered. Isothermal exposures were done for up to 100 h at 871 °C (1600 °F), and comparison was made to similar exposures to air. Exposed samples were characterized in detail using some combination of X-ray diffraction and electron beam scattering and spectroscopic techniques. It was found that chromia scales formed in mixed gases containing water vapor grew much faster and had a finer grain structure than those formed in dry air. Both inward growth and outward growth of the chromia scale were inferred for the mixed-gas conditions. The effect of a high carbon potential in the gas on the scaling behavior is also discussed. Graphical
      PubDate: 2019-02-01
       
  • Oxidation and Hot Corrosion Performance of NiCoCrAlY Coatings Fabricated
           Via Electrolytic Codeposition
    • Abstract: The oxidation and hot corrosion performance of NiCoCrAlY coatings fabricated via electrolytic codeposition was investigated. The cyclic oxidation behavior of NiCoCrAlY coatings on Ni-based superalloys was evaluated at 1000 and 1100 °C. Preliminary Type I hot corrosion testing was conducted to assess the hot corrosion resistance of these coatings in a Dean rig with flowing O2 + 0.1% SO2 gas. NiAl coatings synthesized by a non-contact pack cementation method were included in the oxidation and corrosion tests for comparison. The NiAl coatings exhibited excellent oxidation resistance; however, they showed very poor hot corrosion performance at 900 °C. The electro-codeposited NiCoCrAlY coatings demonstrated good overall resistance to both cyclic oxidation and hot corrosion and also showed better chemical/microstructural compatibility with the superalloy substrates.
      PubDate: 2019-02-01
       
  • Life and FCT Failure of Yttria- and Ceria-Stabilized EBPVD TBC Systems on
           Ni-Base Substrates
    • Abstract: The lifetime at 1100 °C of furnace oxidation tested TBC samples having YSZ (ZrO2-7 wt.% Y2O3) and CeSZ (ZrO2-25 wt.% CeO2-2.5 wt.% Y2O3) topcoats on four Ni-base alloys including a no-bond coat NiCrAl alloy were studied. The thermally grown oxide (TGO) was investigated by energy-dispersive spectroscopy. The outer zone of the TGO revealed preferred enrichment of Zr and of rare earth elements Ce and Y in dependence of the stage of life. The oxygen potential gradients in the TGO have been rated; they are stronger for the YSZ TBC systems than for the CeSZ systems and cause a more intensive interaction of the outer zone alias mixed zone with the metal substrate than with the ceramic topcoat. When comparing the chemical composition data of the mixed zone as a function of the test period, the average lifetime as well as the particular composition of the two topcoats and the refractory element content of the substrates allowed conclusions to be drawn about the mechanisms which influence the lifetime.
      PubDate: 2019-02-01
       
 
 
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