Isothermal and Cyclic Oxidation Behavior of Turbine Blade Alloys

2006 ◽  
Author(s):  
N. S. Cheruvu ◽  
K. T. Chiang
Keyword(s):  
Turbine Blade ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Parabolic Rate Constant ◽  
Isothermal Oxidation ◽  
Isothermal Exposure ◽  
Temperature Oxidation ◽  
Rate Laws ◽  
Parabolic Rate ◽  
Kinetics Of

Oxidation behavior of two nickel-based turbine blade alloys has been investigated at three temperatures ranging from 950°C to 1066°C. Thermogravimetric analysis (TGA), isothermal exposure and cyclic oxidation tests were conducted on GTD-111 (Ni-14.1Cr-3.7W-9.2Co-1.5Mo-3.1A1-4.9Ti-0.02Cb-2.93Ta-0.11C) and IN-738 (Ni-16.0Cr-2.6W-8.1Co-1.6Mo-3.5A1-3.4Ti-0.7Cb-1.6Ta-0.10C) blade alloys. TGA results showed that the oxidation kinetics of both alloys obey parabolic rate laws. The GTD-111 material exhibited a higher parabolic rate constant than IN 738 at all temperatures investigated. Cyclic oxidation behavior of these alloys was compared by plotting the weight change results as a function of thermal cycles. Consistent with the TGA results, cyclic oxidation test results also showed that GTD-111 was less resistant to high-temperature oxidation as compared to the IN-738 alloy. To characterize the oxide scales, a series of short term isothermal oxidation tests were conducted and the spalled scale after oxidation exposure was collected and analyzed by energy-dispersive x-ray analysis (EDX) as a function of aging time. The composition of the scales varied between the alloys. The variation of oxidation behavior of these alloys is discussed with respect to the composition differences between the two alloys.

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

2013 ◽  
Vol 785-786 ◽  
pp. 914-917
Author(s):  
Jun Huai Xiang ◽  
Xian Chao Xu ◽  
Ling Yun Bai ◽  
Yun Xiang Zheng ◽  
Huai Shu Zhang
Keyword(s):  
Oxidation Resistance ◽  
Rate Constant ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Parabolic Rate Constant ◽  
Cooling Process ◽  
Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Si alloys with and without Y in atmosphere at 800 °C was investigated. The addition of 0.3 at.% Y decreased the average parabolic rate constant from 4.45×10-10g2cm-2s-1to 3.58×10-10g2cm-2s-1. The thin scales grown on Co-10Cr-5Si alloys were mainly composed of an outer CoO layer, followed by an inner protective SiO2layer. However, the scales can not be observed for Co-10Cr-5Si-0.3Y alloy, probably due to the spallation of the scales during the cooling process. The addition of 0.3 at.% Y improved the cyclic oxidation resistance of the Co-10Cr-5Al alloy.

Intermediate-temperature oxidation behavior of Ti2AlC in air

2002 ◽  
Vol 17 (11) ◽  
pp. 2974-2981 ◽  
Author(s):  
X. H. Wang ◽  
Y. C. Zhou
Keyword(s):  
Raman Spectroscopy ◽  
Rate Constant ◽  
Oxidation Behavior ◽  
Parabolic Rate Constant ◽  
Oxidation Products ◽  
Scale Morphology ◽  
Temperature Oxidation ◽  
Good Oxidation Resistance ◽  
Parabolic Rate ◽  
Anomalous Oxidation

The isothermal oxidation behavior of Ti2AlC at intermediate temperatures of 500, 600, 700, 800, and 900 °C in flowing air was investigated by means of thermogravimetric analysis, x-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM)/energy dispersive spectroscopy. An anomalous oxidation with higher kinetics at lower temperatures of 500 and 600 °C was observed although Ti2AlC exhibited good oxidation resistance at higher temperatures. As revealed by SEM scale morphology observation, oxidation-induced cracks present at temperatures of 500 and 600 °C resulted in poor protectivity of scales and accounted for the anomalous oxidation. The weight gain data for the remaining temperatures were analyzed with an instantaneous parabolic rate constant method by assuming a parabolic rate law. The variations of instantaneous parabolic rate constant with time reflected the complexity of the oxidation behavior of Ti2AlC at intermediate temperatures. These variations were discussed from the viewpoint of phase transformation of oxidation products on the basis of XRD, Raman spectroscopy, and SEM scale morphology observation. As indicated by XRD and Raman spectra, the scale formed on Ti2AlC at higher temperature was stable α–Al2O3 and rutile TiO2, while transition aluminas of γ–Al2O3, δ–Al2O3, θ–Al2O3, and TiO2 (anatase) were detected at lower temperatures. The whisker morphology of θ–Al2O3 at 800 °C and ridged morphology of α–Al2O3 at 800 and 900 °C were confirmed by SEM.

Effects of Yttrium on Cyclic Oxidation Resistance of Co-10Cr-5Si Alloy at 700 °C

2014 ◽  
Vol 525 ◽  
pp. 154-157
Author(s):  
Jun Huai Xiang ◽  
Xian Chao Xu ◽  
Ling Yun Bai ◽  
Yun Xiang Zheng ◽  
Huai Shu Zhang
Keyword(s):  
Oxidation Resistance ◽  
Rate Constant ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Parabolic Rate Constant ◽  
Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Si alloys with and without Y in atmosphere at 700 °C was investigated. The addition of 0.3 at.% Y decreased the average parabolic rate constant from 4.39×10-10g2cm-2s-1to 3.42×10-10g2cm-2s-1. The surface components with and without Y were both composed of an outer CoO and inner protective SiO2. There were more SiO2formed when Y doped into the alloy. The addition of 0.3 at.% Y improved the cyclic oxidation resistance of the Co-10Cr-5Al alloy.

scholarly journals Isothermal Oxidation Performance of Laser Cladding Assisted with Preheat (LCAP) Tribaloy T-800 Composite Coatings Deposited on EN8

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 843
Author(s):  
Sipiwe Trinity Nyadongo ◽  
Sisa Lesley Pityana ◽  
Eyitayo Olatunde Olakanmi
Keyword(s):  
Iron Oxide ◽  
Composite Coating ◽  
Laser Cladding ◽  
Composite Coatings ◽  
Parabolic Rate Constant ◽  
Mass Gain ◽  
Isothermal Oxidation ◽  
Operational Parameters ◽  
Temperature Oxidation ◽  
Service Environments

It is anticipated that laser cladding assisted with preheat (LCAP)-deposited Tribaloy (T-800) composite coatings enhances resistance to structural degradation upon exposure to elevated-temperature oxidation service environments. The oxidation kinetics of LCAP T-800 composite coatings deposited on EN8 substrate and its mechanisms have not been explored in severe conditions that are similar to operational parameters. The isothermal oxidation behaviour of the T-800 composite coating deposited on EN8 via LCAP was studied at 800 °C in air for up to 120 h (5 × 24 h cycles) and contrasted to that of uncoated samples. The mass gain per unit area of the coating was eight times less than that of the uncoated EN8 substrate. The parabolic rate constant (Kp) for EN8 was 6.72 × 10−12 g2·cm−4·s−1, whilst that for the T-800 composite coating was 8.1 × 10−13 g2·cm−4·s−1. This was attributed to a stable chromium oxide (Cr2O3) layer that formed on the coating surface, thereby preventing further oxidation, whilst the iron oxide film that formed on the EN8 substrate allowed the permeation of the oxygen ions into the oxide. The iron oxide (Fe2O3) film that developed on EN8 spalled, as evidenced by the cracking of oxide when the oxidation time was greater than 72 h, whilst the Cr2O3 film maintained its integrity up to 120 h. A parabolic law was observed by the T-800 composite coating, whilst a paralinear law was reported for EN8 at 800 °C up to 120 h. This coating can be used in turbine parts where temperatures are <800 °C.

Effect of Compressive Stress on the High-Temperature Oxidation Behavior of a Fe-20Ni Alloy in Air

2018 ◽  
Vol 921 ◽  
pp. 168-176
Author(s):  
Chang Hai Zhou ◽  
Rui Yun Pan ◽  
Hai Tao Ma
Keyword(s):  
Compressive Stress ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Oxide Scales ◽  
External Scale ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
X Ray ◽  
High Temperature Oxidation Behavior ◽  
Kinetics Of

The oxidation behavior of Fe-20Ni alloy under compressive stress in air was studied at 800, 900 °C. The results examined by using scanning electron microscope (SEM) and X-ray diffraction (XRD) indicates that the oxide scales were consisted of an external scale and a subscale which has an intragranular scale (above 5 h at 800 °C and 900 °C) and an intergranular scale. Compared with the unstressed specimen, the growth kinetics of external scale was accelerated by an applied compressive stress. Besides, the compressive stress induced an increase in the growths of intragranular scale and intergranular scale formed on the specimens oxidized at 900 °C. However, the effect of compressive stress on the growth of intergranular scale and intragranular scale was not obvious in the case of 800°C. In addition, cracks developed in the subscale for the specimens oxidized under 2.5 MPa compressive stress when the oxidation time exceeded 20 h.

Effects of Yttrium on Cyclic Oxidation Resistance of Co-10Cr-5Al Alloy at 700 °C

2014 ◽  
Vol 528 ◽  
pp. 25-29
Author(s):  
Ling Yun Bai ◽  
Xian Chao Xu ◽  
Jun Huai Xiang ◽  
Yun Xiang Zheng ◽  
Jun Wang
Keyword(s):  
Oxide Scale ◽  
Oxidation Resistance ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Adhesive Property ◽  
Complex Mode ◽  
Rate Law ◽  
Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Al alloys in atmosphere at 700 °C was investigated. The addition of 0.3 at.% Y changed the oxidation behavior from the approximate parabolic rate law to complex mode. The scale grown on the surface of Co-10Cr-5Al cracked seriously, while the oxide scale the Y doped alloy had better adhesive property. Yttrium doped in the sample promoted the forming of continuous Al2O3layer and decreased the oxidation rate of Co-10Cr-5Al alloys.

scholarly journals Additively Manufactured NiTi and NiTiHf Alloys: Estimating Service Life in High-Temperature Oxidation

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2104 ◽  
Author(s):  
Hediyeh Dabbaghi ◽  
Keyvan Safaei ◽  
Mohammadreza Nematollahi ◽  
Parisa Bayati ◽  
Mohammad Elahinia
Keyword(s):  
High Temperature ◽  
Oxidation Rate ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Early Stage ◽  
Niti Alloy ◽  
Temperature Oxidation ◽  
X Ray ◽  
Rate Law ◽  
Parabolic Rate

In this study, the effect of the addition of Hf on the oxidation behavior of NiTi alloy, which was processed using additive manufacturing and casting, is studied. Thermogravimetric analyses (TGA) were performed at the temperature of 500, 800, and 900 °C to assess the isothermal and dynamic oxidation behavior of the Ni50.4Ti29.6Hf20 at.% alloys for 75 h in dry air. After oxidation, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to analyze the oxide scale formed on the surface of the samples during the high-temperature oxidation. Two stages of oxidation were observed for the NiTiHf samples, an increasing oxidation rate during the early stage of oxidation followed by a lower oxidation rate after approximately 10 h. The isothermal oxidation curves were well matched with a logarithmic rate law in the initial stage and then by parabolic rate law for the next stage. The formation of multi-layered oxide was observed for NiTiHf, which consists of Ti oxide, Hf oxide, and NiTiO3. For the binary alloys, results show that by increasing the temperature, the oxidation rate increased significantly and fitted with parabolic rate law. Activation energy of 175.25 kJ/mol for additively manufactured (AM) NiTi and 60.634 kJ/mol for AM NiTiHf was obtained.

Oxidation behavior of bulk Ti3SiC2 at intermediate temperatures in dry air

2006 ◽  
Vol 21 (2) ◽  
pp. 402-408 ◽  
Author(s):  
H.B. Zhang ◽  
Y.C. Zhou ◽  
Y.W. Bao ◽  
J.Y. Wang
Keyword(s):  
Phase Transformation ◽  
Low Temperatures ◽  
Driving Force ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Oxide Scales ◽  
Temperature Oxidation ◽  
Dry Air ◽  
High Oxidation ◽  
Anomalous Oxidation

The isothermal oxidation behavior of bulk Ti3SiC2 at intermediate temperatures from 500 to 900 °C in flowing dry air was investigated. An anomalous oxidation with higher kinetics at lower temperatures was observed. This phenomenon resulted from the formation of microcracks in the oxide scales at low temperatures. The generation of these microcracks was caused by a phase change in the oxide products, i.e., the transformation of anatase TiO2 to rutile TiO2. This phase transformation resulted in tensile stress, which provided the driving force for the formation of the microcracks during oxidation. Despite the existence of microcracks, the intermediate-temperature oxidation of Ti3SiC2 generally obeyed the parabolic rate law and did not exhibit catastrophic destruction due to the fact that cracks occurring in the oxide layers were partially filled with amorphous SiO2. Therefore, further high oxidation kinetics was prevented.

Isothermal oxidation behavior and growth kinetics of silicide coatings formed on Nb–1Zr–0.1C alloy

2015 ◽  
Vol 95 ◽  
pp. 100-109 ◽  
Author(s):  
Sanjib Majumdar ◽  
J. Kishor ◽  
B. Paul ◽  
R.C. Hubli ◽  
J.K. Chakravartty
Keyword(s):  
Growth Kinetics ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Kinetics Of
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