The Experts below are selected from a list of 1686 Experts worldwide ranked by ideXlab platform
Chaurjeng Wang - One of the best experts on this subject based on the ideXlab platform.
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the oxidation behavior of ni2fecocralx high entropy alloys in dry air
Journal of Alloys and Compounds, 2020Co-Authors: W Kai, R T Huang, F P Cheng, Y R Lin, C W Chuang, Da Chen, Jijung Kai, C T Liu, Chaurjeng WangAbstract:Abstract The oxidation behavior of three Ni2FeCoCrAlx high-entropy alloys (where x = 0, 0.5, and 1.0) was studied at 600–900 °C in dry air. The oxidation kinetics of all the alloys obeyed the Parabolic Rate Law at T ≥ 700 °C, with their oxidation Rates steadily increasing with either increasing temperature or decreasing Al content. Discontinuous oxide particles grew on the alloys at 600 °C, while multiple layered scales and an exclusive Al2O3 layer formed on the Al-free and the Al-containing alloys, respectively at T ≥ 700 °C. In addition, an internal nitrogen attack to form AlN was also observed for the Al-containing alloys at 900 °C.
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the high temperature oxidation behavior of hot dipping al si coating on low carbon steel
Surface & Coatings Technology, 2006Co-Authors: Chaurjeng Wang, Shihming ChenAbstract:Low carbon steel was coated by hot-dipping into a molten bath containing Al-10 wt.% Si. The high-temperature oxidation behavior of the specimen was tested at 750, 850 and 950 °C for 72 h in air using a thermobalance. The element distribution, phase composition, and morphology of the aluminide layer and the oxide scale were characterized by OM, XRD and SEM/EDX. After hot-dip treatment, the coating layers consisted of three phases, where Al, FeAl 3 , and Fe 2 Al 5 were detected from external topcoat to the aluminide/steel substRate. The result of high-temperature oxidation test showed oxidation kinetics basically followed the Parabolic Rate Law at all temperatures. The Fe 2 Al 5 formed during the immersion process completely transformed to FeAl 2 , FeAl and α-Fe(Al) phases because of the composition gradient and the chemical diffusion by oxidation. In the present study, Kirkendall voids were found to form at the coating/substRate interface due to the rapid inter-diffusion of iron and aluminum during oxidation and, therefore, the adherence of the coatings should be compromised. Afterwards, loss of protective behavior of coating layer occurred only by iron oxide nodules formed on the coating specimen exposed at 850 °C for 24 h.
Jun Wang - One of the best experts on this subject based on the ideXlab platform.
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surface modification of 2205 duplex stainless steel by low temperature salt bath nitrocarburizing at 430 c
Applied Surface Science, 2013Co-Authors: Runbo Huang, Jun Wang, Si Zhong, Mingxing Li, Ji XiongAbstract:Abstract 2205 stainless steel was modified by salt bath nitrocarburizing at 430 °C in this study. The microstructure, surface hardness and erosion–corrosion resistance were systematically evaluated. Salt bath nitrocarburizing at 430 °C can form a nitrocarburized layer, and with the treated time prolong, the thickness of the layer increased. By nitrocarburizing within 8 h, only expanded austenite (S phase) formed. With treated time increased, CrN gradually diffused from the places where there were ferrite grains in the layer before nitrocarburizing. Besides, the depth increased with the nitrocarburized time and the layer grew approximately conforms to the Parabolic Rate Law. Salt bath nitrocarburizing can effectively improve the surface hardness of 2205 DSS. The erosion–corrosion resistance was improved by salt bath nitrocarburizing and the 16 h treated sample had the best erosion–corrosion behavior.
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influence of time on the microstructure of aisi 321 austenitic stainless steel in salt bath nitriding
Surface & Coatings Technology, 2012Co-Authors: Jun Wang, Qiang Zhang, Runbo HuangAbstract:Abstract Influence of nitriding time on the microstructure and microhardness of AISI 321 austenite stainless steel was investigated, using a complex salt bath heat-treatment at low temperature, 430 °C. Experimental results revealed that after salt bath nitriding, a modified layer was formed on the surface of substRate with the thickness ranging from 2 μm to 30 μm with changing treating time. The nitrided layer depth thickened extensively with increasing nitriding time. The growth of the nitrided layer takes place mainly by nitrogen diffusion according to the expected Parabolic Rate Law. Scanning electron microscopy and X-ray diffraction showed that in 321 stainless steel subjected to complex salt bathing nitrided at such temperature for less than 8 hours, the main phase of the nitrided layer was expanded austenite (S phase) by large. When the treatment time is prolonged up to 8 hours and more, S phase is formed and subsequently transforms partially into CrN, and then the secondary CrN phase precipitated. With treating time prolonged, more CrN precipitates formed along the grain boundaries in the outer part. In the inside part between the some CrN and the substRate, there is still a broad single S phase layer. All treatments can effectively improve the surface hardness.
Harpreet Singh - One of the best experts on this subject based on the ideXlab platform.
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High-temperature oxidation studies of cold-sprayed Ni–20Cr and Ni–50Cr coatings on SAE 213-T22 boiler steel
Applied Surface Science, 2009Co-Authors: N. Bala, Harpreet SinghAbstract:The high-temperature oxidation behavior of cold-sprayed Ni–20Cr and Ni–50Cr coatings on SAE 213-T22 boiler steel has been investigated at 900°C in air under cyclic heating and cooling conditions for 50 cycles. The kinetics of oxidation of coated and bare boiler steel has been established with the help of weight change measurements. It was observed that all the coated and bare steels obeyed Parabolic Rate Law of oxidation. X-ray diffraction, FE-SEM/EDAX and X-ray mapping techniques were used to analyse the oxidation products of the coated and uncoated boiler steel. The uncoated steel suffered corrosion in the form of intense spalling and peeling of its oxide scale, which was perhaps due to the formation of unprotective Fe2O3 oxide scale. Both the coatings showed better resistance to the air oxidation as compared to the uncoated steel. The Ni–50Cr coating was found to be more protective than the Ni–20Cr-coated steel. The formation of oxides and spinels of nickel and chromium may be contributing to the development of air oxidation resistance in the coatings.
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characterization of oxide scales to evaluate high temperature oxidation behavior of ni 20cr coated superalloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Harpreet Singh, Satya Prakash, D Puri, Rabindranath MaitiAbstract:Abstract Modern thermal spray processes such as plasma spraying are usually considered to deposit high-chromium, nickel–chromium coatings onto the superalloys to enhance their high temperature oxidation resistance. The purpose of these coatings is to form long-lasting oxidation protective scales. In the current investigation, Ni–20Cr alloy powder was deposited on three Ni-base superalloys; Superni 75, Superni 600 and Superni 601 by shrouded plasma spray process. Oxidation kinetics was established for the uncoated as well as the coated superalloys in air at 900 °C under cyclic conditions for 50 cycles by thermogravimetric technique. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. All the coated superalloys nearly followed the Parabolic Rate Law of oxidation. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxide scales. The coating was found to be successful in maintaining its integrity with the superalloy substRates in all the cases. The oxide scales formed on the oxidized coated superalloys were found to be intact and spallation-free in general. The XRD analysis revealed the presence of phase like NiO, Cr2O3 and NiCr2O4 in the oxide scales. The XRD results were further supported by the SEM/EDAX analyses.
Satya Prakash - One of the best experts on this subject based on the ideXlab platform.
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high temperature corrosion studies on friction welded low alloy steel and stainless steel in air and molten salt environment at 650 c
Materials & Design, 2012Co-Authors: N Arivazhagan, Satya Prakash, S Narayanan, S P Singh, G M ReddyAbstract:Abstract The investigation on high-temperature corrosion resistance of the weldments is necessary for prolonged service lifetime of the components used in corrosive environments. This paper reports on the performance of friction welded low alloy steel AISI 4140 and stainless steel AISI 304 in air as well as molten salt environment of Na2SO4–60%V2O5 and NaCl–50%Na2SO4 at 650 °C. This paper reports several studies carried out for characterizing the weldments corrosion behavior. Initially thermogravimetric technique was used to establish the kinetics of corrosion. For analyzing the corrosion products, X-ray diffraction, scanning electron microscopy/energy-dispersive analysis and electron probe micro analysis techniques were used. From the results of the experiments, it is observed that the weldments suffered acceleRated corrosion in NaCl–Na2SO4 environment and showed spalling/sputtering of the oxide scale. Furthermore, corrosion resistance of weld interface was found to be lower than that of parent metals in molten salt environment. Weight gain kinetics in air oxidation studies reveals a steady-state Parabolic Rate Law while the kinetics with salt deposits displays multi-stage growth Rates. Moreover NaCl is the main corrosive species in high temperature corrosion, involving mixtures of NaCl and Na2SO4 which is responsible for formation of internal attack.
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high temperature oxidation studies of detonation gun sprayed cr3c2 nicr coating on fe and ni based superalloys in air under cyclic condition at 900 c
Journal of Alloys and Compounds, 2009Co-Authors: Subhash Kamal, R Jayaganthan, Satya PrakashAbstract:Abstract The cyclic oxidation behavior of detonation-gun-sprayed Cr3C2–NiCr coating on three different superalloys namely Superni 75, Superni 718 and Superfer 800H at 900 °C for 100 cycles in air under cyclic heating and cooling conditions has been investigated in the present work. The kinetics of oxidation of coated and bare superalloys was analysed, using thermogravimetric technique. It was observed that all the coated and bare superalloys obey a Parabolic Rate Law of oxidation. X-ray diffraction, FE-SEM/EDAX and X-ray mapping techniques were used to analyse the oxidation products of coated and bare superalloys. The results on the Cr3C2–NiCr-coated superalloys showed better oxidation resistance due to the formation of a compact and adhesive thin Cr2O3 scale on the surface of the coating during oxidation. The scale remained intact and adherent to the partially oxidised coating during cyclic oxidation due to its good compatibility and similar thermal expansion coefficient between Cr3C2–NiCr coating and the superalloy substRates. In all the coated superalloys, the chromium, iron, silicon and titanium were oxidised in the inter-splat region, whereas splats which consisted mainly of Ni remained unoxidised. The Parabolic Rate constants of Cr3C2–NiCr-coated alloys were lower than that of the bare superalloys as observed in the present work.
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characterization of oxide scales to evaluate high temperature oxidation behavior of ni 20cr coated superalloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Harpreet Singh, Satya Prakash, D Puri, Rabindranath MaitiAbstract:Abstract Modern thermal spray processes such as plasma spraying are usually considered to deposit high-chromium, nickel–chromium coatings onto the superalloys to enhance their high temperature oxidation resistance. The purpose of these coatings is to form long-lasting oxidation protective scales. In the current investigation, Ni–20Cr alloy powder was deposited on three Ni-base superalloys; Superni 75, Superni 600 and Superni 601 by shrouded plasma spray process. Oxidation kinetics was established for the uncoated as well as the coated superalloys in air at 900 °C under cyclic conditions for 50 cycles by thermogravimetric technique. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. All the coated superalloys nearly followed the Parabolic Rate Law of oxidation. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxide scales. The coating was found to be successful in maintaining its integrity with the superalloy substRates in all the cases. The oxide scales formed on the oxidized coated superalloys were found to be intact and spallation-free in general. The XRD analysis revealed the presence of phase like NiO, Cr2O3 and NiCr2O4 in the oxide scales. The XRD results were further supported by the SEM/EDAX analyses.
R T Huang - One of the best experts on this subject based on the ideXlab platform.
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the oxidation behavior of ni2fecocralx high entropy alloys in dry air
Journal of Alloys and Compounds, 2020Co-Authors: W Kai, R T Huang, F P Cheng, Y R Lin, C W Chuang, Da Chen, Jijung Kai, C T Liu, Chaurjeng WangAbstract:Abstract The oxidation behavior of three Ni2FeCoCrAlx high-entropy alloys (where x = 0, 0.5, and 1.0) was studied at 600–900 °C in dry air. The oxidation kinetics of all the alloys obeyed the Parabolic Rate Law at T ≥ 700 °C, with their oxidation Rates steadily increasing with either increasing temperature or decreasing Al content. Discontinuous oxide particles grew on the alloys at 600 °C, while multiple layered scales and an exclusive Al2O3 layer formed on the Al-free and the Al-containing alloys, respectively at T ≥ 700 °C. In addition, an internal nitrogen attack to form AlN was also observed for the Al-containing alloys at 900 °C.
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the oxidation behavior of cu zr ti base bulk metallic glasses in air at 350 500 c
Oxidation of Metals, 2007Co-Authors: H H Hsieh, R T Huang, W Kai, W L Jang, P Y Lee, W H WangAbstract:The oxidation behavior of two Cu-base bulk metallic glasses (BMGs), having compositions Cu–30Zr–10Ti and Cu–20Zr–10Ti–10Hf (in at.%), was studied over the temperature range of 350–500 °C in dry air. In general, the oxidation kinetics of both BMGs followed the Parabolic Rate Law, with the oxidation Rates increasing with increasing temperature. The addition of Hf slightly reduced the oxidation Rates at 350–400 °C, while the opposite results observed at higher temperatures. It was found that the oxidation Rates of both BMGs were significantly higher than those of polycrystalline pure-Cu. The scales formed on both BMG alloys were strongly composition dependent, consisting of mostly CuO/Cu2O and minor amounts of cubic-ZrO2 and ZrTiO4 for the ternary BMG, and of CuO, cubic-ZrO2, and Zr5Ti7O24 for the quaternary BMG. The formation of ternary oxides (ZrTiO4 and Zr5Ti7O24) was inferred to be responsible for the fast oxidation Rates of the BMGs.
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high temperature corrosion behavior of iron aluminides containing ternary additions in h2 h2s h2o mixed gases
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1997Co-Authors: R T HuangAbstract:Abstract The high-temperature corrosion behavior of four iron aluminides containing Fe–18Al (in at.%) and three Fe–18Al–5M alloys (where M was Cr, Mn, or Mo) was studied over the temperature range of 700–900°C in a H 2 /H 2 S/H 2 O atmosphere. The corrosion kinetics followed the Parabolic Rate Law in all cases, regardless of temperature and alloy composition. The Parabolic Rate constants decreased with decreasing temperature, and the addition of ternary elements resulted in various decreases in the corrosion Rate compared with Fe–18Al. It was found that Mo was effective to improve the corrosion resistance at T ≤800°C while Cr had a better improvement at 900°C. The scales formed on all iron aluminides were strongly dependent on temperature and ternary addition.
