Effect of Nb Content on Cyclic Oxidation Behavior of As-Cast Ti-1100 Alloys

The cyclic oxidation behaviors of the as-cast Ti-1100-xNb (x = 0.5, 1.0, 1.5, 2.0) alloys exposed at 650 °C for up to 100 h were systematically investigated. The aim of this work is to explore the in-depth oxidation mechanism by using the oxidation kinetics and the structure of the oxide products. The oxidation kinetics were determined by thermogravimetrically, and the microstructure and composition of the oxidation scale were studied by using XRD and SEM. The results demonstrate that Nb can significantly improve the oxidation resistance. However, the average weight gains of the alloys decrease firstly and then increase with the increase of Nb content. The oxidation kinetics obeys a parabolic model. The Ti-1100-1.0Nb alloy has the lowest kp value, which is 5.7 × 10−13 g2cm−4s−1. The surface oxidation products are mainly composed of massive or acicular rutile-TiO2, TixO (x = 3, 6), NbO2 and Al2O3. Besides, Al2(MoO4)3 oxide is also presented on the oxidation surface of the Ti-1100-1.5Nb alloys. Ti-1100-1.0Nb alloy shows the best oxidation resistance property revealed by combining weight gains and EDS-SEM element content profiles analysis. The interaction of Nb, O, Ti, and other elements retarded the diffusion of O atoms into the alloys, which improves the oxidation resistance.

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Cyclic Oxidation Resistance of Co-10Cr-5Al-0.3Y Alloy at 800 oc

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1015.505 ◽

2014 ◽

Vol 1015 ◽

pp. 505-508

Author(s):

Ling Yun Bai ◽

Hong Hua Zhang ◽

Huai Shu Zhang ◽

Yun Xiang Zheng ◽

Jun Huai Xiang

Keyword(s):

Oxidation Resistance ◽

Oxidation Rate ◽

Cyclic Oxidation ◽

Oxidation Behavior ◽

Oxidation Process ◽

Oxidation Mechanism ◽

Local Zone

The cyclic oxidation behavior of Co-10Cr-5Al alloys with and without 0.3 at% Y doped in atmosphere at 800oC was investigated. The addition of 0.3 at.% Y increased the oxidation rate of the alloy and changed the oxidation mechanism. The scales grown the alloys with and without Y were both composed of an outer Co2O3layer and an inner complex layer of Al2O3, Co2O3and Cr2O3, except that the addition of 0.3 at% Y enhanced the adhesion of the scale. 0.3 at% Y agglomerated in local zone which accelerated the oxidation rate and was not conductive to the oxidation process of the Co-10Cr-5Al alloy.

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Effects of Yttrium on Cyclic Oxidation Resistance of Co-10Cr-5Al Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.785-786.844 ◽

2013 ◽

Vol 785-786 ◽

pp. 844-847

Author(s):

Jun Huai Xiang ◽

Xian Chao Xu ◽

Ling Yun Bai ◽

Yun Xiang Zheng ◽

Huai Shu Zhang

Keyword(s):

Oxidation Resistance ◽

Oxidation Kinetics ◽

Oxidation Rate ◽

Cyclic Oxidation ◽

Oxidation Behavior ◽

Oxidation Process ◽

Local Zone ◽

Rate Law ◽

Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Al alloys with and without Y in atmosphere at 800 °C was investigated. The addition of 0.3 at.% Y increased the oxidation rate of the alloy and changed the behavior from irregular oxidation kinetics to approximate parabolic rate law. The scales grown the alloys with and without Y were both composed of an outer Co2O3layer and an inner complex layer of Al2O3, Co2O3and Cr2O3, except that the addition of Y impaired the adhesion of the scale. Over-doped Y agglomerated in local zone plays an adverse role in the oxidation process by accelerating the oxidation rate.

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Application of Silicon for a Protection of Titanium against High-Temperature Oxidation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.482.243 ◽

2005 ◽

Vol 482 ◽

pp. 243-246 ◽

Cited By ~ 2

Author(s):

Dalibor Vojtěch ◽

Tomáš Kubatík ◽

Hana Čížová

Keyword(s):

High Temperature ◽

Oxidation Resistance ◽

High Temperature Oxidation ◽

Cyclic Oxidation ◽

Oxidation Mechanism ◽

Positive Influence ◽

Surface Alloying ◽

Temperature Oxidation

The paper describes a positive influence of silicon on the high-temperature oxidation resistance of titanium. Since silicon additions can be realized both by bulk and by surface alloying, the surface siliconizing techniques, as well as structure of the Si-rich layers, are illustrated. Furthermore, the high-temperature cyclic oxidation resistance of the surface siliconized titanium and of the TiSi2 alloy are compared to that of pure Ti and TiAl6V4 alloy, and the oxidation mechanism is discussed.

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High Temperature Cyclic Oxidation of Coatings on Ni-Based Superalloys

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.226.137 ◽

2015 ◽

Vol 226 ◽

pp. 137-142

Author(s):

Marta Kianicová ◽

Jaroslav Trník

Keyword(s):

Oxidation Resistance ◽

Cyclic Oxidation ◽

Oxidation Products ◽

Thermo Gravimetric ◽

Good Oxidation Resistance ◽

Heating And Cooling ◽

University Of Technology ◽

Al Coating ◽

Kinetics Of ◽

Cylindrical Samples

The cyclic oxidation behavior of diffusion protective Al and SiAl coatings used on Ni-superalloy namely MAR-M247 at 1100°C for 38 cycles in the air under cyclic heating and cooling conditions has been investigated in the present work. Cyclic oxidation test was carried out in laboratories of Silesian University of Technology in Katowice, Poland. Cylindrical samples were casted from mentioned alloy in factory PBS Velká Bíteš, a.s., Czech Republic. The oxidation kinetics of coated and uncoated superalloys was analyzed by thermo-gravimetric technique. It was observed that all the coated and bare superalloys obey a parabolic rate law of oxidation. SEM/EDX techniques were used to analyses the oxidation products of all samples. MAR-M247 with Al coating showed good oxidation resistance due to the formation of a compact and adhesive thin Al2O3 scale on the surface of the coating during oxidation. SiAl coating showed equally good oxidation resistance. The oxidation progress of uncoated alloy MAR-M247 was very fast.

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Study on the Pre-Oxidation and Resulting Oxidation Mechanism and Kinetics of Mo-9Si-8B Alloy

Materials ◽

10.3390/ma14185309 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5309

Author(s):

Cheng Wang ◽

Qiuliang Li ◽

Zhenping Guo ◽

Xiangrong Li ◽

Xiangyu Ding ◽

...

Keyword(s):

High Temperature ◽

Oxidation Resistance ◽

High Temperature Oxidation ◽

Cyclic Oxidation ◽

Initial Period ◽

Oxidation Mechanism ◽

Protective Layer ◽

Temperature Oxidation ◽

Locking Mechanism ◽

Kinetics Of

Molybdenum silicon boron alloy is regarded as the next generation of superalloy that is expected to replace nickel-based superalloys. However, the high-temperature oxidation resistance of Mo-Si-B alloy has always been an issue worth studying. In this study, Mo-9Si-8B alloy was prepared via a plasma oscillatory pressure sintering process and pre-oxidized at 1300 °C while maintaining a certain balance of mechanical and oxidation properties. The influence of the oxide protective layer on its performance at high temperature of 1150 °C was explored, the micro-mechanism of its performance and its failure mode of the hinge-locking mechanism was illustrated, and finally, its oxidation kinetics was inferred. In conclusion, pre-oxidized Mo-9Si-8B (at.%) alloy did play a role in delaying the oxidation process during the initial period of cyclic oxidation. However, with the increase of cyclic oxidation time, the improvement of high-temperature oxidation resistance was limited.

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

Coatings ◽

10.3390/coatings10040376 ◽

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.

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Influence of Micro-Structure on Oxidation Behavior of a Ni-Based Superalloy at 1000°C

Materials Science Forum ◽

10.4028/www.scientific.net/msf.595-598.87 ◽

2008 ◽

Vol 595-598 ◽

pp. 87-94 ◽

Cited By ~ 2

Author(s):

Li Liu ◽

Ying Li ◽

Fu Hui Wang

Keyword(s):

Oxide Scale ◽

Oxidation Resistance ◽

Cyclic Oxidation ◽

Oxidation Behavior ◽

Flat Surface ◽

Cast Alloy ◽

Oxidation Mechanism ◽

Micro Structure ◽

Al2o3 Layer ◽

Oxidation Behaviors

The isothermal and cyclic oxidation behaviors of a Ni-based superalloy with singlecrystalline (SC), polycrystalline and nanocrystalline (NC) structures were studied at 1000°C. Results indicated that a uniform oxides scale consisted of external Cr2O3 with little TiO2 and internal continuous Al2O3 formed on SC alloy. A non-uniform external oxide of which some locations were nodule-like scale was formed on surface of cast alloy. The nodule-like parts consisted of TiO2, Cr2O3 and serious internal oxidation of Al, and rest flat surface was a Cr2O3 and Al2O3 layer. A continuous Al2O3 layer formed on the sputtered NC coating. The micro-structure influenced the oxidation mechanism and resulted in different oxide scale formed on three materials, which greatly influenced materials’ oxidation and cyclic-oxidation resistance.

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