Effects of Different Surface Native Pre-Oxides on the Hot Corrosion Properties of Nickel-Based Single Crystal Superalloys

A study is carried out on the effect of different surface native pre-oxides on hot corrosion of single crystal nickel-based superalloy at 900 °C. The effect of different oxides formed by different superalloys through pre-oxidation on hot corrosion is verified by normal hot corrosion and tube sealing experiments. The relationship between different surface oxides and the effect of different surface oxides layer on the hot corrosion properties of alloys are studied. In summary, the stable and dense surface pre-Al2O3 layer which can be obtained by pre-oxidation has an obvious positive effect on the improvement of superalloy hot corrosion resistance in reaction. In addition, the internal sulfides are analyzed in depth, and the relationship between Cr, Mo, O and S is discussed in detail.

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Corrosion behavior of new type Co-based superalloys with different Ni contents

Corrosion Reviews ◽

10.1515/corrrev-2017-0003 ◽

2017 ◽

Vol 35 (6) ◽

pp. 455-462 ◽

Cited By ~ 2

Author(s):

Bo Gao ◽

Lei Wang ◽

Yang Liu ◽

Xiu Song ◽

Shu-Yu Yang ◽

...

Keyword(s):

Corrosion Resistance ◽

Corrosion Behavior ◽

Hot Corrosion ◽

Corrosion Layer ◽

Corrosion Process ◽

Corrosion Properties ◽

Oxidation Processes ◽

Ni Content ◽

Ni Addition ◽

New Type

AbstractThe corrosion properties of γ′-strengthened Co-xNi-Al-W-Cr (where x=15, 20, 25, and 30 at.%) superalloys were investigated in the mixture of 75 wt.% Na2SO4+25 wt.% NaCl at 900°C. The results showed that the corrosion behavior is associated with both sulfuration and oxidation processes. It was demonstrated that increasing the addition of Ni effectively promoted the formation of continuous Al2O3 scales, so that the hot corrosion resistance could be improved. When Ni content is more than 20 at.%, a large amount of Ni3S2 precipitates during the corrosion process. Sulfuration can destroy the integrity of the corrosion layer and increase the activity of oxygen. In this way, the internal oxidation of the alloys becomes more serious. Therefore, it is recommended that the optimum Ni addition is about 20 at.% for new type Co-Ni-Al-W-Cr superalloys.

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Effect of Re and Ta on Hot Corrosion Resistance of Nickel-base Single Crystal Superalloys

Superalloys 2016 ◽

10.1002/9781119075646.ch20 ◽

2016 ◽

pp. 177-185 ◽

Cited By ~ 1

Author(s):

J.X. Chang ◽

D. Wang ◽

G. Zhang ◽

L.H. Lou ◽

J. Zhang

Keyword(s):

Corrosion Resistance ◽

Single Crystal ◽

Hot Corrosion ◽

Nickel Base

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Optimization of pre-oxidation time for corrosion resistance of cobalt based coating alloy in mixed sulphates

Anti-Corrosion Methods and Materials ◽

10.1108/acmm-03-2020-2270 ◽

2021 ◽

Vol 68 (1) ◽

pp. 29-35

Author(s):

Abdul Rehman ◽

Mohammad Hassan Shirani Bidabadi ◽

Liang Yang ◽

Zheng Yu ◽

Chen Hao ◽

...

Keyword(s):

Corrosion Resistance ◽

Hot Corrosion ◽

Design Methodology ◽

Corrosion Behaviour ◽

Ambient Air ◽

Oxidation Time ◽

Oxidation Treatment ◽

Content Type ◽

Surface Oxides ◽

Oxidation Effect

Purpose This study aims to optimise the effect of pre-oxidation on hot corrosion behaviour of Tribaloy T-900 at 900 °C in mixed Na2SO4 and K2SO4. Design/methodology/approach Prior to hot corrosion experiment, pre-oxidation treatments were carried in ambient air at 900 °C for 1, 5 and 10 h, respectively. The hot corrosion experiments were performed in a box type furnace at 900 °C. Both surfaces of specimens were brushed with saturated salt solution of 75 wt.% Na2SO4 + 25 wt.% K2SO4. After brushing, the salt-coated specimens were placed in electric stove to ensure drying of salt. After drying, presence of 3 mg/cm2 salt on specimen’s surface was ensured through weighting. Findings The 1-h pre-oxidation treatment prior to hot corrosion showed superior hot corrosion resistance against molten salt attack. An optimum pre-oxidation time of 1 h helped timely formation of protective Cr2O3 layer and inhibited the formation of less stable and porous surface oxides of Ni and Mo during hot corrosion. Originality/value Pre-oxidation effect on hot corrosion behaviour of refractory metal (such as Mo in investigated alloy) containing alloy has never been reported previously. Refractory metals oxide (e.g. MoO3) could transform the corrosion phenomena to catastrophic failure through acidic fluxing.

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Mechanism of adding rhenium to improve hot corrosion resistance of nickel-based single-crystal superalloys

Rare Metals ◽

10.1007/s12598-020-01584-1 ◽

2020 ◽

Author(s):

Fang-Min Yang ◽

Li-Xian Lian ◽

Ying Liu ◽

Xiu-Fang Gong

Keyword(s):

Corrosion Resistance ◽

Single Crystal ◽

Hot Corrosion

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Evaluation of Hot Corrosion Resistance of Directionally Solidified Nickel-Based Superalloy

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.227.337 ◽

2015 ◽

Vol 227 ◽

pp. 337-340 ◽

Cited By ~ 2

Author(s):

Maria Sozańska ◽

Barbara Kościelniak ◽

Lucjan Swadźba

Keyword(s):

Corrosion Resistance ◽

Chemical Composition ◽

Hot Corrosion ◽

Turbine Blades ◽

Nickel Superalloy ◽

Material Surface ◽

Scale Morphology ◽

Directionally Solidified ◽

Nickel Based Superalloy ◽

Two Temperatures

The turbine blades made of directionally solidified nickel-based superalloys are exposed to combination of high temperature and aircraft environment, in which appear corrosive elements like sulphur, sodium and vanadium (hot corrosion). Corrosion resistance of superalloys is mainly dependent on their structure and chemical composition. Therefore, it is important to be aware of the correlation between the hot corrosion and changes in chemical composition and morphology of a surface of the material. The following paper presents the influence of sulphur on the microstructure of directionally solidified nickel-based superalloy. The research was carried out in Na2SO4 environment at two temperatures of 850oC and 900oC (below and above the melting point of salt, 884°C). The results show scale morphology on material surface and changes in chemical composition of surface of nickel superalloy.

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Surface Modification of Magnesium with Rare Earth Conversion Films for Biomedical Protection

Materials Science Forum ◽

10.4028/www.scientific.net/msf.546-549.601 ◽

2007 ◽

Vol 546-549 ◽

pp. 601-604 ◽

Cited By ~ 2

Author(s):

Jia Cheng Gao ◽

Yan Xue ◽

Li Ying Qiao ◽

Yong Wang ◽

Yan Zhang

Keyword(s):

Corrosion Resistance ◽

Rare Earth ◽

Metabolic Process ◽

The Body ◽

Surface Microstructure ◽

Corrosion Properties ◽

Corrosion Rates ◽

Protective Films ◽

Relationship Of ◽

The Relationship

The specific gravity and elastic modulus of magnesium alloys are similar to that of human bone. Magnesium is one of the most important elements in the human body and plays a key role in the metabolic process. But the application of magnesium is seriously limited as a biomaterial since it corrodes easily in the physiological environment of the body. In order to reduce the corrosion, we developed protective films using rare earth (RE) conversion processing. The surface of magnesium samples was modified by contact with different rare-earth salt solutions; then the samples were dipped in SBF to test their corrosion resistance. The change of mass and the pH of the solutions were measured continuously using an electronic scale and a pH micrometer. The surface microstructure of the samples was observed by XRD and metallomicroscope. Corrosion rates of the samples in SBF were determined using Taffier curve. The preliminary results show that the conversion treatment with CeCl3 or Y(NO3)3 can improve the corrosion resistance of magnesium in SBF. The relationship of the RE salts concentration and the corrosion properties were studied,the best combination of parameters was determined, and the formation mechanism of rare-earth conversion film has been also elaborated.

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