Phase Constitution and Oxidation Resistance of B2 (Ir, Co)Al

2002 ◽  
Vol 753 ◽  
Author(s):  
Hideki Hosoda ◽  
Hiroshi Noma ◽  
Kenji Wakashima
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Hot Forging ◽  
Isothermal Oxidation ◽  
Oxidation Products ◽  
Phase Constitution ◽  
Temperature Oxidation ◽  
Arc Melting ◽  
Oxidation Resistant ◽  
Ultrahigh Temperature

ABSTRACTB2 iridium aluminide (IrAl) is hopeful for use as an ultrahigh temperature oxidation resistant coating above 1600K. In this study, the effect of Co substitution for Ir on phase constitution, hardness and oxidation behavior was studied for IrAl alloys. Alloys of (Ir, Co)-50mol%Al with various Co contents were fabricated by Ar-arc melting followed by hot-forging at 1773K. Oxidation behavior was evaluated using thermogravimetry (TG) in Ar-67%O2 up to 1823K. XRD and SEM were also carried out for alloy characterization. It was found that a continuous B2 solid solution (Ir,Co)Al is formed between IrAl and CoAl. Depending on the Co concentration, the oxidation products identified after heating to 1873K in Ar-67%O2 were Ir, IrO2 and A2O3 and/or Co2AlO4. Thin and continuous Al2O3 layers were observed after isothermal oxidation at 1673K when Co content is more than 20mol%Co. In this case, the weight change by isothermal oxidation at 1673K becomes higher with decreasing Co content. The (Ir,Co)Al alloys containing 20–40mol%Co exhibit higher oxidation resistance than CoAl and IrAl, and thus oxidation resistance of CoAl is improved by Ir addition.

Improvement in the Oxidation Resistance of β-SiAlON Ceramics Produced from Mechanically Milled Powders

2012 ◽  
Vol 18-19 ◽  
pp. 281-290
Author(s):  
Onur Eser ◽  
S. Kurama
Keyword(s):  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Isothermal Oxidation ◽  
High Energy ◽  
Particle Sizes ◽  
Temperature Oxidation ◽  
Dry Air ◽  
Milled Powders

In the present study the oxidation behavior of β-SiAlON ceramics, which were produced from conventional and high energy mechanical milled powders, was investigated. High energy mechanically milled powders have lower particle sizes ( 130 nm) than those of conventional powders (216 nm) and fully densified at lower temperatures with less amount of additives. The amount of additive is an important parameter to improve the high temperature oxidation resistance of SiAlON ceramics. The cyclic and isothermal oxidation tests were carried out at 1300 and 1400°C in dry air environment. The weight gain of oxidized samples was measured during the oxidation process. The alteration of oxide layer was analyzed by XRD and SEM. The results indicate that oxidation resistance of the samples produced from mechanically milled powders with less amount of additive is higher than that of conventional one. Therefore, β-SiAlON ceramics which were sintered at 100°C lower temperatures with less amount of additive (3.5 wt. % Y2O3), showed a better oxidation resistance.

scholarly journals Investigation on Optimal Ta/Cr Ratio of a Single Crystal Ni-Base Superalloy in View of the Isothermal Oxidation Behavior

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1421
Author(s):  
Jianxiu Chang ◽  
Wenhao Feng ◽  
Wenwen Zhao ◽  
Hongmin Jia ◽  
Yanming Liu ◽  
...  
Keyword(s):  
Single Crystal ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Nitride Layer ◽  
Oxidation Products ◽  
Competitive Growth ◽  
X Ray Diffraction ◽  
Al2o3 Layer ◽  
Oxidation Performance

The relative content of strengthening element tantalum (Ta) and oxidation-resistant element chromium (Cr) is an essential value for superalloys to obtain an excellent combination of oxidation resistance and mechanical properties. In the present paper, the isothermal oxidation behavior of several single crystal Ni-base superalloys with different Ta/Cr (wt. %, similarly hereinafter) ratios at 1000 °C in static air has been systematically investigated to explore the optimal Ta/Cr for excellent oxidation resistance. A detailed microstructure study using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and an electro-probe microanalyzer (EPMA) was performed to reveal the oxidation products and mechanisms. For all alloys, a three-layer structured scale consisting of an outer (Cr, Al, Ti, Ni, Ta)-O layer, an inner Al2O3 layer and an inner nitride layer was formed. As Ta/Cr increased, the amounts of Ta-containing products, cracks, holes and inner nitride increased. Meanwhile, the completeness of the Al2O3 layer got worse. It was shown that if Ta/Cr ≤ 0.5, Ta increased the growth rate of Cr2O3 via the doping effect induced by Ta cations. If Ta/Cr > 0.5, Ta reduced the completeness of Cr2O3 through competitive growth of Ta2O5 and Cr2O3. A good oxidation performance can be expected with the value Ta/Cr ≤ 0.5.

Microstructure and High Temperature Oxidation Resistance of TiC/Ti-25Al Composites

2011 ◽  
Vol 287-290 ◽  
pp. 514-517
Author(s):  
Hui Gai Wang ◽  
Yan Pei Song ◽  
Fei Wang ◽  
Zun Jie Wei
Keyword(s):  
Oxidation Resistance ◽  
Cross Section ◽  
Energy Dispersive Spectrometer ◽  
Oxidation Kinetic ◽  
Isothermal Oxidation ◽  
Matrix Composites ◽  
Temperature Oxidation ◽  
Arc Melting ◽  
Long Time ◽  
Surface Morphologies

With the reaction between titanium (Ti) sponge, high purity aluminum (Al) and TiC/Al inter-alloy, non-consumable arc melting technique has been successfully used in situ synthesize Ti matrix composites of Ti-25Al and Ti-25Al-1.5C. The composites oxidized at 900°C for 5~60h in static air. The influences of carbon content to oxidation kinetics of composites were analyzed. The surface morphologies and cross-section microstructures of the oxidation scales were examined by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS). The results show that the isothermal oxidation kinetic curves of composites mainly follow parabolic rate law. The surface oxides of two materials are mainly columnar TiO2, while the grain size of Ti-25Al-1.5C is smaller than that of Ti-25Al. The cross-section microstructure of the oxidation scales of Ti-25Al are layered constructions which grow in alternating way. The oxides of Ti-25Al-1.5C are mainly around the carbide particles, the oxidation resistance of which is stronger than Ti-25Al when oxidized for long time.

scholarly journals Investigation on the High-Temperature Oxidation Resistance of Ni-(3~10) Ta and Ni-(3~10) Y Alloys

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 97 ◽  
Author(s):  
Hang Duan ◽  
Yan Liu ◽  
Tiesong Lin ◽  
Hui Zhang ◽  
Zhengren Huang
Keyword(s):  
Oxide Layer ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Vacancy Concentration ◽  
Mass Gain ◽  
Isothermal Oxidation ◽  
Vacuum Arc ◽  
Oxygen Vacancy Concentration ◽  
Positive Role ◽  
Temperature Oxidation

Ni-(3~10) Ta and Ni-(3~10) Y alloys were fabricated by vacuum arc melting. The oxidation resistance of the alloys was studied by cyclic and isothermal oxidation tests at 800 °C in static air. The present work focused on the investigation of the effects of the alloying elements (Ta and Y) on the oxidation behavior of Ni-based alloys. The oxidation behavior of alloys was evaluated by mass gain, composition, as well as the microstructure of oxidized products. The experimental results indicated that Ta at a low content (3 wt %) had a positive role in enhancing oxidation resistance by decreasing the oxygen vacancy concentration of the oxide layer to prevent the inward diffusion of oxygen during oxidation, and the mass gain decreased from 2.9 mg·cm−2 to 1.7 mg·cm−2 (800 °C/200 h), while Y (3~10 wt %) degraded the oxidation resistance. However, it is worth mentioning that the pinning effect of Y2O3 increased the adhesion between the substrate and oxide layer by changing the growing patterns of the oxide layer from a plane growth to fibrous growth. Among the results, the bonding of the substrate and oxide layer was best in the Ni-3Y alloys.

Oxidation Behavior and Pack Siliconized Oxidation-Resistant Coatings of an Nb-Based Ultrahigh Temperature Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 371-374 ◽  
Author(s):  
X.P. Guo ◽  
L.X. Zhao ◽  
Ping Guan ◽  
K. Kusabiraki
Keyword(s):  
Oxidation Resistance ◽  
Double Layer ◽  
Outer Layer ◽  
Oxidation Behavior ◽  
Layer Structure ◽  
Transitional Layer ◽  
Double Layer Structure ◽  
Oxidation Resistant ◽  
Ultrahigh Temperature ◽  
Two Phases

The halide-activated pack cementation method was utilized to deposit silicide coatings on a multicomponent Nb-Ti-Si based alloy. The siliconized temperature was 1150 °C and the holding time was 10h. Both the specimens with siliconized coatings and without coatings were oxidized at 1250°C for 5, 10, 20, 50 and 100h respectively. The coating possessed a double layer structure with the composition of (Nb,X)Si2 (X represents Ti, Cr and Hf), and the outer layer was denser. The major structure in the outer layer was composed of columnar crystals perpendicular to the interface between the coating and the substrate, and that in the inner layer was mainly composed of equiaxed crystals. A transitional layer about 5μm thick was found between the coating and the substrate. After oxidation at 1250°C, the major constituents in the scale were SiO2 and TiO2 and the mole ratio of these two phases was about 2:1. The thickness of the (Nb,X)Si2 layer decreased and that of transitional layer increased as the oxidation time prolonged. The siliconized coating exhibited excellent oxidation-resistance at 1250°C within 50 hours.

scholarly journals High-Temperature Oxidation Behavior of a Cu-Bearing 17Cr Ferritic Stainless Steel

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Mengqi Zhang ◽  
Ying Han ◽  
Guoqing Zu ◽  
Jiapeng Sun ◽  
Weiwei Zhu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Weight Gain ◽  
Oxidation Resistance ◽  
Ferritic Stainless Steel ◽  
Oxidation Kinetics ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Element Distribution ◽  
Temperature Oxidation ◽  
Good Oxidation Resistance

The isothermal oxidation behavior of 17Cr-0.85Si-0.5Nb-1.2Cu ferritic stainless steel in air was studied from 850°C to 1050°C by analyzing its weight gain after oxidation. The kinetic curves were plotted using the oxidation weight-gain data, and the structure, surface morphology, and element distribution of the oxide films were analyzed by XRD, SEM, and EDS. The results showed that the oxidation kinetics curves at 850°C and 950°C followed a parabolic law, and a continuous and dense oxide film composed of Cr2O3 and MnCr2O4, FeCr2O4, and Cu-Cr rich spinel was formed, which reveals that the steel displayed good oxidation resistance. When the temperature was increased to 1050°C, the oxidation kinetics curves gradually changed from parabolic to linear after 40 h exposure, which indicated that the oxidation resistance significantly worsened. A lower oxidation resistance was observed at 1050°C due to the formation of a large amount of Fe2O3 on the surface and the volatilization of the inner Cr2O3 layer.

A Perspective on Modeling Materials in Extreme Environments: Oxidation of Ultrahigh-Temperature Ceramics

MRS Bulletin ◽  
2006 ◽  
Vol 31 (5) ◽  
pp. 410-418 ◽  
Author(s):  
Angelo Bongiorno ◽  
Clemens J. Först ◽  
Rajiv K. Kalia ◽  
Ju Li ◽  
Jochen Marschall ◽  
...  
Keyword(s):  
Modeling And Simulation ◽  
Atomistic Simulation ◽  
Extreme Environments ◽  
Protective Layer ◽  
Ceramic Composites ◽  
Atomistic Modeling ◽  
Temperature Oxidation ◽  
Simulation Techniques ◽  
Oxidation Resistant ◽  
Ultrahigh Temperature

AbstractThe broader context of this discussion, based on a workshop where materials technologists and computational scientists engaged in a dialogue, is an awareness that modeling and simulation techniques and computational capabilities may have matured sufficiently to provide heretofore unavailable insights into the complex microstructural evolution of materials in extreme environments.As an example, this article examines the study of ultrahigh-temperature oxidation-resistant ceramics, through the combination of atomistic simulation and selected experiments.We describe a strategy to investigate oxygen transport through a multi-oxide scale—the protective layer of ultrahigh-temperature ceramic composites ZrB2-SiC and HfB2-SiC—by combining first-principles and atomistic modeling and simulation with selected experiments.

ENHANCING HIGH-TEMPERATURE OXIDATION RESISTANCE OF TITANIUM ALLOY WITH KF110-B4C-Ag THROUGH LASER TECHNOLOGY

2021 ◽  
Author(s):  
ZHAO ZHANG ◽  
JIANING LI ◽  
ZHIYUN YE ◽  
CAINIAN JING ◽  
MENG WANG ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Mass Gain ◽  
Temperature Oxidation ◽  
Laser Technology ◽  
X Ray ◽  
Ta15 Titanium Alloy ◽  
Oxidation Resistant

In this paper, the high-temperature oxidation resistant coating on the TA15 titanium alloy by laser cladding (LC) of the KF110-B4C-Ag mixed powders was analyzed in detail. The scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS) images indicated that a good metallurgy bond between the fabricated coating/TA15 was formed; also the fine/compact microstructure was produced after a cladding process. The oxidation mass gain of TA15 was higher than that of the coating after LC process, which were 3.72 and 0.91[Formula: see text]mg[Formula: see text]cm[Formula: see text], respectively, at 60[Formula: see text]h, greatly enhancing the high temperature oxidation resistance.

Isothermal Oxidation Behavior of a New Directionally Solidified Ni-Base Superalloy in Air at Different Temperature

2010 ◽  
Vol 654-656 ◽  
pp. 538-541
Author(s):  
Lei Wang ◽  
Yan Huang ◽  
Zhuo Zhao ◽  
Yang Liu ◽  
Jian Tao Wu ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Oxidation Behaviour ◽  
Diffusion Activation Energy ◽  
Directionally Solidified ◽  
Temperature Range ◽  
Parabolic Law ◽  
Diffusion Activation ◽  
Base Superalloy

The isothermal oxidation behaviour under static atmosphere of a new directionally solidified Ni-base superalloy was investigated. The results showed that the oxidation kinetics curves of the alloy follow parabolic law in the temperature range of 750-950°C. The diffusion activation energy Q is to be about 244.86 kJ•mol-1 and the oxidation within this temperature range is mainly controlled by Cr3+ diffusion among Cr2O3 oxidation film. The oxidation resistance grade of the alloy is perfect anti-oxidation within 750-850°C, and anti-oxidation within 900-950°C. The oxidation film can be divided into TiO2, Cr2O3+TiTaO4+NiCr2O4, Al2O3 and TiN layers, from the surface to inside. Priority oxidation and the inside oxidation of Al are considered with the oxidation of Ti and the depletion of Cr, and it is the key point for the improving of oxidation resistance.

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