scholarly journals The Influence of Aluminum Content on Oxidation Resistance of New-Generation ODS Alloy at 1200 °C

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1478 ◽  
Author(s):  
Luděk Stratil ◽  
Vít Horník ◽  
Petr Dymáček ◽  
Pavla Roupcová ◽  
Jiří Svoboda
Keyword(s):  
Oxidation Resistance ◽  
Cross Sections ◽  
Aluminum Content ◽  
Energy Dispersive Spectrometer ◽  
Oxide Dispersion Strengthened ◽  
Xrd Analysis ◽  
Al Content ◽  
Α Al2o3 ◽  
New Generation ◽  
Ods Alloy

The aim of the paper is to evaluate the effect of aluminum content on the oxidation resistance of new-generation of oxide dispersion strengthened (ODS) alloy at 1200 °C. Three grades of the alloy of chemical composition Fe-15Cr-xAl-4Y2O3 with different Al contents x = 0.3 wt.%, 2.0 wt.% and 5.5 wt.% are prepared by mechanical alloying. The alloys are consolidated by high temperature rolling followed by heat treatment. To study the oxidation resistance the samples are isothermally aged in the air for 1 h, 4 h, 16 h and 64 h at 1200 °C. The oxidation kinetics, composition and formation mechanism of the oxide layers are analyzed. The weight gain of prepared steels is estimated. The kinetics of oxidation is studied on metallographic cross-sections of the exposed samples by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analysis. The oxides on the surfaces are identified by X‑ray diffraction (XRD) analysis. The Al content significantly enhances the oxidation resistance of the alloy. For a sufficiently high Al content in the alloy a compact oxide layer of α‑Al2O3 on the surface is formed, which significantly suppresses further oxidation process.

scholarly journals High Temperature Cyclic Plastic Response of New-Generation ODS Alloy

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 804
Author(s):  
Alice Chlupová ◽  
Ivo Šulák ◽  
Jiří Svoboda
Keyword(s):  
High Temperature ◽  
Oxide Dispersion Strengthened ◽  
Step Test ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Oxide Dispersion ◽  
Ods Alloys ◽  
New Generation ◽  
Near Future ◽  
Ods Alloy

The very recently developed coarse-grained new-generation oxide dispersion strengthened (ODS) alloys containing 5 vol.% homogeneously distributed yttrium nano-precipitates seems to be a promising oxidation-resistant structural material for applications at temperatures above 1000 °C. The primary aim of the present paper is the introduction of the new-generation oxide dispersion strengthened (ODS) alloy and the first testing of its high temperature fatigue properties at 800 °C, concurrently demonstrating a novel and very efficient methodology by using an incremental fatigue step test. The successful application of the methodology motivates the authors to test the fatigue properties of new generation ODS alloys at 1000–1200 °C in the near future.

scholarly journals Effects of Al Sputtering Film on the Oxidation Behavior of NiCrAlY Bondcoat

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 376
Author(s):  
Yong Zhang ◽  
Gengfei Zhang ◽  
Qiang Yang ◽  
Weicheng Cao ◽  
Jian Pu ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Thermal Barrier Coatings ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Mixed Oxides ◽  
Oxidation Mechanism ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Al Content ◽  
Α Al2o3

In this study, the oxidation behavior of Al coated NiCrAlY bondcoat is investigated. It is known that many methods are applied to improve the lifetime of bondcoat in thermal barrier coatings. Herein, the Al sputtering method is selected to increase the Al content, which does not change the structure of bondcoat. Thin Al film of ~2 µm was sputtered on the surface of bondcoat, which improved the oxidation resistance of NiCrAlY bondcoat. Experimental results showed that, after oxidation for 200 h at 1200 °C, the formation of a dense and continuous α-Al2O3/Cr2O3 multilayer was observed on the Al coated bondcoat surface. In contrast, a mixed oxides (NiO, Cr2O3 and spinel oxides) layer formed on the surface of the as-sprayed bondcoat samples. Results of the cyclic oxidation at 1050 °C within 204 h indicated that the Al sputtering method can improve the oxidation resistance of bondcoat. This study offers a potential way to prolong the lifetime of thermal barrier coatings and provides analysis of the oxidation mechanism.

scholarly journals Influence of Hot Consolidation Conditions and Cr-Alloying on Microstructure and Creep in New-Generation ODS Alloy at 1100 °C

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5070 ◽  
Author(s):  
Jiří Svoboda ◽  
Natália Luptáková ◽  
Milan Jarý ◽  
Petr Dymáček
Keyword(s):  
Hot Rolling ◽  
Secondary Recrystallization ◽  
Oxide Dispersion Strengthened ◽  
Coarse Grained ◽  
Mechanically Alloyed ◽  
Creep Properties ◽  
Ods Alloys ◽  
Rolling Temperatures ◽  
New Generation ◽  
Ods Alloy

The coarse-grained new-generation Fe-Al-Y2O3-based oxide dispersion strengthened (ODS) alloys contain 5 vol.% homogeneously dispersed yttria nano-precipitates and exhibit very promising creep and oxidation resistance above 1000 °C. The alloy is prepared by the consolidation of mechanically alloyed powders via hot rolling followed by secondary recrystallization. The paper presents a systematic study of influence of rolling temperature on final microstructure and creep at 1100 °C for two grades (Fe-10Al-4Y2O3 and Fe-9Al-14Cr-4Y2O3 in wt%) of new-generation ODS alloys. The hot rolling temperatures exhibit a rather wide processing window and the influence of Cr-alloying on creep properties is evaluated as only slightly positive.

scholarly journals Fundamental Improvement of Creep Resistance of New-Generation Nano-Oxide Strengthened Alloys via Hot Rotary Swaging Consolidation

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5217
Author(s):  
Jiří Svoboda ◽  
Lenka Kunčická ◽  
Natália Luptáková ◽  
Adam Weiser ◽  
Petr Dymáček
Keyword(s):  
Volume Fraction ◽  
Secondary Recrystallization ◽  
Grain Morphology ◽  
Oxide Dispersion Strengthened ◽  
High Volume ◽  
Coarse Grained ◽  
Mechanically Alloyed ◽  
Rotary Swaging ◽  
New Generation ◽  
Ods Alloy

New-generation oxide dispersion-strengthened (ODS) alloys with a high volume fraction of nano-oxides of 5% are intended to become the leading creep- and oxidation-resistant alloys for applications at 1100–1300 °C. Hot consolidation of mechanically alloyed powders by intensive plastic deformation followed by heat treatment of the alloys are the key aspects for achieving top creep properties, typically ensured by a coarse-grained microstructure strengthened with homogeneously dispersed, very stable yttrium nano-oxides. The rotary swaging method proves to be favourable for hot consolidation of the new-generation ODS alloy presented. Compared to specimens consolidated by hot rolling, consolidation by hot rotary swaging predetermines the formation of coarse grains with a very high aspect ratio during subsequent secondary recrystallization. Such a grain morphology increases the creep strength of the new-generation ODS alloy considerably.

Comparative study of conventional and microwave heating of polyacrylonitrile-based fibres

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guozhen Zhao ◽  
Jianhua Liu ◽  
Lei Xu ◽  
Shenghui Guo
Keyword(s):  
Microwave Heating ◽  
Surface Defects ◽  
Energy Dispersive Spectrometer ◽  
Xrd Analysis ◽  
Economic Benefits ◽  
Heating Time ◽  
Oxidation Temperature ◽  
Conventional Heating ◽  
Heating Method ◽  
Molecular Arrangement

Abstract The effects of the conventional heating method and the microwave heating method on polyacrylonitrile-based fibres in the temperature range of 180–280 °C were investigated. Fourier transform infrared spectroscopy, X-ray wide-angle scattering, Raman spectroscopy, energy-dispersive spectrometer, scanning electron microscopy and bulk density were used to characterise the properties of the samples. Results show that the microwave heating method can shorten the pre-oxidation time, reduce pre-oxidation temperature and reduce the number of surface defects. The pre-oxidised fibres obtained by the microwave heating method exhibit not only good crystallite size but also a smooth surface. Atomic morphology and molecular arrangement are orderly inside the fibre. The FT-IR spectrum shows that the oxidation reaction occurs at 220 °C, and the CI value of PAN fibers stabilised by microwave heating is the larger than the fibers stabilised by conventional heating. XRD analysis shows that fibers stabilised by microwave heating have low stack domains. The SEM and Raman spectra indicate that hydrogen peroxide can improve the surface finish of the fibers and reduce defects. Microwave heating can reduce the pre-oxidation temperature by about 20 °C and shorten the heating time. The economic benefits of using this method are significantly improved.

Li(Ni1/3Co1/3Mn1/3)O2 with High Rate Capability Synthesized via a Novel Gel-Combustion Method

2011 ◽  
Vol 391-392 ◽  
pp. 973-977
Author(s):  
Jing Mao ◽  
Ke Hua Dai ◽  
Yu Chun Zhai
Keyword(s):  
Energy Dispersive Spectrometer ◽  
Rate Capability ◽  
Chelating Agent ◽  
Combustion Method ◽  
Xrd Analysis ◽  
High Rate ◽  
High Rate Capability ◽  
Sem Images ◽  
Gel Combustion ◽  
Gel Combustion Method

Li(Ni1/3Co1/3Mn1/3)O2material with high rate capability was synthesized by a novel gel-combustion method using polyvinylpyrrolidone as a polymer chelating agent and a fuel. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to study the structure, morphology and element distribution of the Li(Ni1/3Co1/3Mn1/3)O2material. XRD analysis showed that all samples were α-NaFeO2structure and Li(Ni1/3Co1/3Mn1/3)O2prepared at 900 °C had the highest c/a of 4.977 indicating the highest layered-ness. EDS scan demonstrated that the precursor was homogeneous. SEM images indicated all samples were well crystallized. Charge and discharge tests showed all samples had good rate capability. Among them, Li(Ni1/3Co1/3Mn1/3)O2prepared at 900 °C had the highest capacity and the best rate capability. It delivered 162.1 mAh•g−1at 0.25 C between 2.5 and 4.3 V and the capacity retention was about 81% compared to that of 0.25C rate.

scholarly journals Silicon reduces aluminum content in tissues and ameliorates its toxic effects on potato plant growth

2016 ◽  
Vol 46 (3) ◽  
pp. 506-512 ◽  
Author(s):  
Athos Odin Severo Dorneles ◽  
Aline Soares Pereira ◽  
Liana Verônica Rossato ◽  
Gessieli Possebom ◽  
Victória Martini Sasso ◽  
...  
Keyword(s):  
Chemical Element ◽  
Shoot Growth ◽  
Aluminum Content ◽  
Solanum Tuberosum L ◽  
Toxic Effects ◽  
Al Content ◽  
Potato Plants ◽  
High Affinity ◽  
Root And Shoot Growth ◽  
Tolerant Genotype

ABSTRACT: Aluminum (Al) is highly toxic to plants, causing stress and inhibiting growth and silicon (Si) is considered beneficial for plants. This chemical element has a high affinity with Al. The aim of this study was to investigate the potential of Si to mitigate the toxic effects of Al on potato ( Solanum tuberosum L.) plants and assess whether this behavior is different among genotypes with differing degrees of sensitivity to Al. Potato plants of the genotypes SMIJ319-7 (Al-sensitive) and SMIF212-3 (Al-tolerant) were grown for fourteen days in nutrient solution (without P and pH 4.5±0.1) under exposure to combinations of Al (0 and 1.85mM) and Si (0, 0.5 and 1.0mM). After this period, shoot and roots of the two genotypes were collected to determine Al content in tissues and assess morphological parameters of root and shoot growth. Roots of both genotypes accumulated more Al than shoots and the Al-tolerant genotype accumulated more Al than the sensitive one, both in roots and in shoot. Furthermore, the presence of 0.5 and 1.0mM Si together with Al reduced the Al content in shoot in both genotypes and in roots of the Al-tolerant genotype, respectively. Si ameliorated the toxic effects of Al with regard to number of root branches and leaf number in both potato genotypes. Si has the potential to mitigate the toxic effects of Al in potato plants regardless of Al sensitivity.

Effect of Phase Fraction Ratio Between Al3Mg2 and Mg2Si on the Oxidation Behavior of Al–Mg–Si Alloys

2021 ◽  
Vol 16 (7) ◽  
pp. 1047-1051
Author(s):  
Seong-Ho Ha ◽  
Abdul Wahid Shah ◽  
Bong-Hwan Kim ◽  
Young-Ok Yoon ◽  
Hyun-Kyu Lim ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
High Temperatures ◽  
Cross Sections ◽  
Oxidation Behavior ◽  
Eutectic Phase ◽  
Mg Alloy ◽  
Phase Fraction ◽  
The Matrix ◽  
Si Content

The effect of the phase fraction ratio between Al3Mg2 and Mg2Si on the oxidation resistance of Al–Mg–Si alloys at high temperatures was investigated. With addition of 1 mass%Si in Al-6 mass%Mg alloy, the as-cast microstructures showed formation of Mg2Si phase by eutectic reactions. With increasing Si content more than 3 mass%, the Mg2Si and Si are formed as eutectic phases with no β-Al3Mg2 phase. In addition, with an increase in the Si content from 3 mass%, significantly refined as-cast microstructures and distribution of extended eutectic phase areas were observed. The oxidized cross-sections of Al-6 mass%Mg and Al-6 mass%Mg-1 mass%Si alloys showed coarse and dark areas, which are considered as oxide clusters, nonuniformly grown into the matrix. However, Al-6 mass%Mg-3 mass%Si and Al-6 mass%Mg-5 mass%Si alloys had no significantly grown oxide clusters on the surfaces. Based on the results, it was concluded that the reduction of the ratio between β-Al3Mg2 and Mg2Si phases can reduce the rapid oxidation of Mg.

Effect of Al on microstructure and mechanical properties of as-cast Mg-8Gd-4Y-1Zn alloy

2020 ◽  
Vol 67 (1) ◽  
pp. 101-105
Author(s):  
Yongxin Zhou ◽  
Qian Li ◽  
Zhiguo Xing ◽  
Renze Zhou ◽  
Zhenhua Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Material Characterization ◽  
Aluminum Content ◽  
Gravity Casting ◽  
Content Type ◽  
Al Content ◽  
Casting Technology ◽  
Microstructure And Mechanical Properties ◽  
Lpso Structure

Purpose This paper aims to investigate the effect of aluminum addition on the microstructure and mechanical properties of Mg-8Gd-4Y-1Zn alloy. Design/methodology/approach Mg-8Gd-4Y-1Zn-xAl (x = 0, 0.5, 1.0, 1.5, 2.0 Wt.%) alloys were prepared by the conventional gravity casting technology, and then microstructures, phase composition and mechanical properties were investigated by material characterization method, systematically. Findings Results show that the as-cast microstructure of Mg-8Gd-4Y-1Zn alloy mainly consists of a-Mg matrix as well as Mg12REZn (18 R LPSO structure), and island-like Mg3(RE, Zn) phase is distributed at the grain boundary. The addition of a small amount of Al (0.5 Wt.%) can decrease the content of island-like Mg3(RE, Zn) phase, but significantly increase the content of long-period stacking ordered (LPSO) structure, resulting in the improvement of both tensile strength and elongation of Mg-8Gd-4Y-1Zn alloy. However, the addition of excessive Al will consume Re element and decrease the amount of LPSO structure, leading to the decrease of tensile properties. When the content of Al is 0.5 Wt.%, the tensile strength and elongation are 225 MPa and 9.0% of Mg-8Gd-4Y-1Zn alloy, which are 14% and 29% higher than that of Mg-8Gd-4Y-1Zn alloy, respectively. Originality/value Adding aluminum to Mg-8Gd-4Y-1Zn alloy strengthens its mechanical properties. And the effect of Al content on the alloy strengthening. The formation mechanism of LPSO structure with different aluminum content was revealed.

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