Effect of Pack Cementation Temperature on Oxidation Behavior of NiCoCrAl Coated Layer

2015 ◽  
Vol 1112 ◽  
pp. 353-358 ◽  
Author(s):  
Eni Sugiarti ◽  
Kemas A. Zaini ◽  
Yong Ming Wang ◽  
Naoyuki Hashimoto ◽  
Somei Ohnuki ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Oxidation Mechanism ◽  
Intermediate Stage ◽  
Pack Cementation ◽  
Coated Sample ◽  
Initial Oxidation ◽  
Oxidation Stage ◽  
And Diffusion

The oxidation behavior of NiCoCrAl coatings deposited on carbon steel was evaluated at 800 °C for 100 h in atmospheric air. The effect of different coating process on the oxidation of carbon steel was studied. The oxidation mechanism was discussed based on oxidation rate, formation of oxide scale, and microstructure of the coated sample. The oxidation rate significantly increased owing to the formation of metastable Al2O3 during initial oxidation stage. The oxidation rate decreased due to the transformation from d, q to a-Al2O3 from the intermediate stage up to final stage of 100 h oxidation. The effect of pack cementation temperature contributed to the thickness and diffusion of coated elements. The experimental results showed that sample developed at 800 °C exhibited better oxidation resistance than sample developed at 900 and 1000 °C.

scholarly journals Oxidation Behavior of Ferritic Steel T22 Exposed to Supercritical Water

2019 ◽  
Vol 38 (2019) ◽  
pp. 476-484 ◽  
Author(s):  
Zhongliang Zhu ◽  
Hasan Izhar Khan ◽  
Qi Cao ◽  
Naiqiang Zhang
Keyword(s):  
Iron Oxide ◽  
Supercritical Water ◽  
Layered Structure ◽  
Outer Layer ◽  
Ferritic Steel ◽  
Oxidation Behavior ◽  
Spinel Oxide ◽  
Initial Oxidation ◽  
Exposure Temperature ◽  
Oxidation Stage

AbstractThe oxidation tests of Ferritic Steel T22 exposed to supercritical water (SCW) at 540–620°C and 25 MPa was performed for up to 1000 h. The oxidation rate increased with increasing exposure temperature and time. Oxide films formed on T22 have a double-layered structure with an outer layer consisting of iron oxide and an inner layer consisting of spinel oxide. Numerous pores on the surface can be observed at the initial oxidation stage while they seemed to heal with increasing exposure time at 620°C. Cracks occurred along grain boundaries in the oxide scale when T22 exposed for 200 h at 620°C. The influence of time and temperature on the oxidation of Ferritic Steel T22 was discussed.

Comparison Study of Oxidation Behavior of Low Carbon Steel at Elevated Temperatures

2014 ◽  
Vol 1025-1026 ◽  
pp. 504-508 ◽  
Author(s):  
Sang An Ha ◽  
Dong Kyun Kim ◽  
Woo Jin Lee ◽  
Chang Yong Kang ◽  
Kwon Hoo Kim ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Low Carbon Steel ◽  
Comparison Study ◽  
Low Carbon ◽  
Increasing Temperature ◽  
Continuous Oxidation

Comparison study of oxidation behavior of low carbon steel was conducted at the temperature range of 500°C to 700°C under a 0.2 atm oxygen pressure by continuous and discontinuous oxidation methods. Oxidation rate of both cases was found to be increased with increasing temperature from 500°C to 700°C and obeyed parabolic rate law. In addition, activation energy for the continuous oxidation of steel was found to be a 164.8 kJ/mole, which means that oxidation rate is proportionally dependant on temperature. In case of cyclic oxidation, the oxidation rate was shown to faster than continuous oxidation at all temperatures due to direction oxidation through spallation of the oxide layer.

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

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.

Oxidation Behavior of T91 Steel in Water Vapor Atmosphere at 750°C

2014 ◽  
Vol 941-944 ◽  
pp. 193-197
Author(s):  
Guang Ming Liu ◽  
Cai Fu Wang ◽  
Gang Liu ◽  
Zhi Lei Liu ◽  
Ji Hong Tian
Keyword(s):  
Water Vapor ◽  
Oxidation Behavior ◽  
Early Stage ◽  
Oxidation Mechanism ◽  
Sample Surface ◽  
Mass Gain ◽  
Initial Stage ◽  
Oxidation Stage ◽  
Water Vapor Atmosphere ◽  
Gain Stage

The oxidation behavior of T91 steel in Ar-10%H2O atmosphere at 750°C was investigated. The morphology, microstructures and composition of oxide scales were examined by SEM/EDS and XRD. The results showed that the oxidation kinetics followed logarithmic law in the initial stage and parabolic law in the latter stage. At the early stage Cr-rich oxide film formed on the sample surface, which led to slow mass gain stage. In the latter oxidation stage, Fe ions diffused outward, resulting in fast oxidation stage. The oxidation scales consisted of two layers, an porous Fe2O3outer layer and an denser Cr-rich inner layer. Some cracks were formed between the inner and outer layers. The oxidation mechanism of T91 in water-vapor atmosphere at high temperature was discussed in brief.

Oxidation of MoSi2/SiC nanolayered composite

1998 ◽  
Vol 13 (4) ◽  
pp. 965-973 ◽  
Author(s):  
J-P. Hirvonen ◽  
P. Torri ◽  
R. Lappalainen ◽  
J. Likonen ◽  
H. Kung ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Composite Material ◽  
Steady State ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Secondary Ion Mass Spectrometry ◽  
Degradation Mechanism ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Initial Oxidation

The oxidation behavior of a nanolayered MoSi2/SiC composite material was determined at the temperature range of 400–900 °C in wet oxidation conditions. The samples were produced in the form of thin films using a sputtering technique from two different sources, and a rotating substrate holder, onto silicon single crystals and low carbon steel. For comparison, the oxidations of both constituents, MoSi2 and SiC, produced with the same sputtering technique, were measured separately. The microstructure of the MoSi2/SiC samples was determined with high resolution transmission electron microscopy (HRTEM), and the composition of the sputtered samples was measured using backscattering (BS) of protons. For quantitative determination of oxidation, the nuclear reaction 16O(d, p)17O was utilized. Oxide layers were also analyzed using a secondary ion mass spectrometry (SIMS) and the appearance of the oxidized surface with a scanning electron microscopy (SEM). As expected, the SiC films had both the lowest initial oxidation and steady state oxidation rate. The results show that the oxidation behavior of the MoSi2/SiC nanolayered composite material differs from that of both its constituents and involves a degradation mechanism of its own, resulting in the highest oxidation during the initial phase of the oxidation. A steady-state oxidation rate was observed after the initial transient phase to be the highest for the metastable C40 structure of the single MoSi2 layer. The oxidation rate of the nanolayered structure was retarded by the SiC layers. No signs of pest disintegration were observed on either of the MoSi2 containing coatings during the steady-state phase of the oxidation at 500 °C up to 40 h. Our results show that the oxidation of nanolayered structures can be only in part explained by the oxidation behavior of the constituents and that during the steady-state oxidation of the nanolayered structure the oxidation rate is largely determined by the constituent with the lowest oxidation rate and by the layered structure.

Model Calculation of SiC Oxidation Rates in the Thin Oxide Regime

2008 ◽  
Vol 600-603 ◽  
pp. 663-666 ◽  
Author(s):  
Yasuto Hijikata ◽  
Takeshi Yamamoto ◽  
Hiroyuki Yaguchi ◽  
Sadafumi Yoshida
Keyword(s):  
Growth Rate ◽  
Model Calculation ◽  
Oxidation Mechanism ◽  
Oxide Thickness ◽  
Emission Model ◽  
Initial Oxidation ◽  
Oxidation Rates ◽  
Oxidation Stage ◽  
Thin Oxide

To explain the growth rate enhancement of SiC oxidation in the thin oxide regime, which was recently found from the real time monitoring experiments of the initial oxidation stage of SiC (000–1) C-face using an in-situ spectroscopic ellipsometer, we tried to apply the interfacial Si emission model, which has been originally proposed for Si oxidation, and found that the Si emission model successfully reproduced the SiC oxidation rates at the whole range of oxide thickness and at oxidation temperatures measured. By comparing with the simulations for Si oxidation, we have discussed the oxidation mechanism of SiC.

scholarly journals Effect of Al2O3 and SiO2 Inert-Fillers on the Microstructural Evolution and High Temperature Oxidation Resistance of B Modified Silicides Coatings Prepared by Pack Cementation Technology

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 700
Author(s):  
Linfen Su ◽  
Guanqun Zhuo ◽  
Haiwen Song ◽  
Jianyong Yang ◽  
Kaiyong Jiang
Keyword(s):  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Oxidation Process ◽  
Pack Cementation ◽  
Oxidation Products ◽  
Initial Oxidation ◽  
Temperature Oxidation ◽  
Good Oxidation Resistance ◽  
Inert Filler ◽  
Oxidation Stage

In this study, B modified silicide coatings were prepared on Nb-Si based alloy with Al2O3 or SiO2 inert-filler by pack cementation technology. Both coatings primarily consisted of a (Nb,X)Si2 with a (Nb,X)B2 + (Nb,X)Si2 outer layer. After oxidation at 1250 °C for 100 h, the coatings showed good oxidation resistance due to the formation of a dense silica. The oxidation products of the coating prepared with Al2O3 inert-filler consisted of SiO2, TiO2 and Cr2O3, while that of the coating prepared with SiO2 inert-filler consisted of SiO2, TiO2, Cr2O3, and HfO2. The different oxidation products may be due to the different oxidation process of these two sample at initial oxidation stage.

scholarly journals Oxidation behavior of non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution powders in air

2021 ◽  
Author(s):  
Huilin Lun ◽  
Yi Zeng ◽  
Xiang Xiong ◽  
Ziming Ye ◽  
Zhongwei Zhang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Group Iv ◽  
Hypersonic Vehicles ◽  
Metal Carbides ◽  
Initial Oxidation ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Kinetics Of

AbstractMulti-component solid solutions with non-stoichiometric compositions are characteristics of ultra-high temperature carbides as promising materials for hypersonic vehicles. However, for group IV transition-metal carbides, the oxidation behavior of multi-component non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution has not been clarified yet. The present work fabricated four kinds of (Zr,Hf,Ti)Cx carbide solid solution powders by free-pressureless spark plasma sintering to investigate the oxidation behavior of (Zr,Hf,Ti)Cx in air. The effects of metallic atom composition on oxidation resistance were examined. The results indicate that the oxidation kinetics of (Zr,Hf,Ti)Cx are composition dependent. A high Hf content in (Zr,Hf,Ti)Cx was beneficial to form an amorphous Zr-Hf-Ti-C-O oxycarbide layer as an oxygen barrier to enhance the initial oxidation resistance. Meanwhile, an equiatomic ratio of metallic atoms reduced the growth rate of (Zr,Hf,Ti)O2 oxide, increasing its phase stability at high temperatures, which improved the oxidation activation energy of (Zr, Hf, Ti)Cx.

Atomically Smooth Ultrathin Oxide Layers on SI(113)

1999 ◽  
Vol 567 ◽  
Author(s):  
H.-J. Müssig ◽  
J. Dabrowski ◽  
S. Hinrich
Keyword(s):  
Elevated Temperatures ◽  
Oxidation Mechanism ◽  
Dissociative Chemisorption ◽  
Initial Oxidation ◽  
Precursor State ◽  
Oxide Layers ◽  
Adsorption Sites ◽  
Molecular Precursor ◽  
Diffusion Paths ◽  
Ultrathin Oxide

ABSTRACTWe report the first direct observation of dissociative chemisorption of oxygen molecules on a silicon surface at room temperature via a molecular precursor state. We link this to the fact that smooth oxide layers can be grown easily on Si(113). The process of initial oxidation is discussed in terms of surface diffusion paths and surface stress. First ab initiocalculations help elucidate the favored adsorption sites and the oxidation mechanism. Experimental evidence was found for bond geometries resulting in the quasi-epitaxial growth of a chemisorption layer on the substrate at elevated temperatures (600°C). In contrast to the first stages of Si(001) oxidation, neither defects nor the ejection of Si atoms plays a significant role during the initial oxidation of Si(113).

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