scholarly journals Performance of air plasma sprayed Cr3C2-25NiCr and NiCrMoNb coated X8CrNiMoVNb16-13 alloy subjected to high temperature corrosion environment

2022 ◽  
Author(s):  
P Subramani ◽  
M Sathishkumar ◽  
M Manikandan ◽  
S Senthil Kumaran ◽  
V Sreenivasulu ◽  
...  
Keyword(s):  
Weight Gain ◽  
High Temperature ◽  
Bond Strength ◽  
Molten Salt ◽  
Environmental Conditions ◽  
Xrd Analysis ◽  
Vital Role ◽  
Air Plasma ◽  
Air Oxidation ◽  
Plasma Sprayed

Abstract Thermal barrier coating plays a vital role in protecting materials' surfaces from high-temperature environment conditions. This work compares the demeanour of uncoated and air plasma sprayed Cr3C2-25NiCr and NiCrMoNb coated X8CrNiMoVNb16-13 substrates subjected to air oxidation and molten salt (Na2SO4 + 60%V2O5) environment condition at 900°C for 50 cycles. Coating characteristics have been analyzed through microstructure, thickness, porosity, hardness, and bond strength. SEM, EDS and XRD analysis were used to analyze corrosion's product at the end of the 50th cycle. Coating microstructures showed a uniform laminar structure that is adherent and denser with a coating thickness of 150 ± 20 μm and porosity less than 3.5%. The Microhardness of both the coated substrates were higher than that of the bare substrate. Cr3C2-25NiCr and NiCrMoNb coating bond strength was 38.9 MPa and 42.5 MPa. Thermogravimetric analysis showed the parabolic rate law of oxidation for all the substrates in both environments. In the molten salt environment, all the substrates exhibited higher weight gain compared to the air oxidation environment. In both environmental conditions, the uncoated X8CrNiMoVNb16-13 alloy exhibited higher weight gain than the coated substrates. The formation of Cr2O3, NiO and spinel oxide NiCr2O4 offers good resistance to corrosion to all the substrates in both the environmental condition. However, the presence of Mo and Nb significantly accelerated the corrosion of the substrate, thereby increasing the weight of the NiCrMoNb substrate. It is observed that Cr3C2-25NiCr and NiCrMoNb coating over the X8CrNiMoVNb16-13 substrate significantly protected the substrate against the hot corrosion than the bare alloy exposed to similar environmental conditions.

Hot Corrosion Studies on GTA Welded AISI 304, Monel 400 Subjected to Air Oxidation and Molten Salt Environment

2011 ◽  
Vol 383-390 ◽  
pp. 4688-4692
Author(s):  
Ramkumar K. Devendranath ◽  
N. Arivazhagan ◽  
S Narayanan
Keyword(s):  
Molten Salt ◽  
Hot Corrosion ◽  
Gta Welding ◽  
Xrd Analysis ◽  
Air Oxidation ◽  
Aisi 304 ◽  
Nickel Copper ◽  
Steel Aisi ◽  
Monel 400 ◽  
Marine Applications

An attempt was made to study the hot corrosion behavior on gas tungeten arc welded Austenitic stainless steel AISI 304 and Nickel-copper alloy Monel 400. These materials are widely used in power plant, petro-chemical and marine applications where the weldments are usually subjected to aggressive corrosion environment. GTA welding was carried out using ENiCu-7 and E308L filler wires. Various regions of the weldment of AISI 304, Monel 400 were exposed to the air oxidation as well as in the molten salt environment consist of K2SO4 + NaCl (60%) at 700°C. Mechanical properties of the weldments were also studied. The corrosion products of the weldments were analyzed using SEM/EDAX, XRD analysis.

Investigation of High Emissivity Coatings Prepared by Plasma Spraying

2011 ◽  
Vol 287-290 ◽  
pp. 2283-2287
Author(s):  
Can Wang ◽  
Quan Sheng Wang ◽  
Xian Jin Ning ◽  
Zhong Du ◽  
Yan Bo Liu ◽  
...  
Keyword(s):  
Bond Strength ◽  
Bulk Density ◽  
Plasma Spraying ◽  
Infrared Emissivity ◽  
Air Plasma ◽  
Air Plasma Spraying ◽  
Feedstock Powder ◽  
Plasma Sprayed ◽  
Normal Emissivity ◽  
High Emissivity

In this study, the feedstock powder for plasma spray was prepared by spray drying and post-sintering at 1360 °C using raw metal oxides. The high emissivity coating was deposited by air plasma spraying (APS). The microstructure, phase structure, flowability and bulk density of the plasma sprayed powder were characterized. The microstructure, bond strength and infrared emissivity of the high emissivity coating were also analyzed in this paper. The results reveal that the feedstock powder present good flowability of 42.36 (sp50g) with the bulk density of 1.94 gpml and is suitable for plasma spraying. A dense coating with the bond strength of 39.6MPa and the porosity less than 5 percent was prepared successfully. The normal emissivity of the coating in all waveband is 0.88 at 300°C and 0.87 at 600°C.

The behaviour of air-plasma-sprayed zirconia in high temperature reactor helium

1982 ◽  
Vol 95 (3) ◽  
pp. 245-254 ◽  
Author(s):  
A.R. Nicoll ◽  
W. Kleemann ◽  
R. Engel
Keyword(s):  
High Temperature ◽  
Air Plasma ◽  
High Temperature Reactor ◽  
Plasma Sprayed

Corrigendum to “Air-plasma-sprayed thermal barrier coatings that are resistant to high-temperature attack by glassy deposits” [Acta Mater 58 (2010) 6835–6844]

2011 ◽  
Vol 59 (5) ◽  
pp. 2241 ◽  
Author(s):  
Julie M. Drexler ◽  
Kentaro Shinoda ◽  
Angel L. Ortiz ◽  
Dongsheng Li ◽  
Alexander L. Vasiliev ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Acta Mater ◽  
Glassy Deposits ◽  
Plasma Sprayed

scholarly journals Phase Analysis and Microstructural Investigations of Ce2Zr2O7 for High-Temperature Coatings on Ni-Base Superalloy Substrates

2019 ◽  
Vol 38 (2019) ◽  
pp. 773-782 ◽  
Author(s):  
G. Venkatesh ◽  
R. Subramanian ◽  
L. John Berchmans
Keyword(s):  
High Temperature ◽  
Parabolic Rate Constant ◽  
Xrd Analysis ◽  
Thermally Grown Oxide ◽  
Coated Sample ◽  
Inconel 625 ◽  
Oxide Growth ◽  
Air Plasma ◽  
Microscopy Characterization ◽  
Base Superalloy

AbstractCrystalline cerium-zirconate (CZ) powders were synthesized via solution-assisted combustion synthesis route and calcined at 850°C for 8 h to obtain coarse crystalline powders. SEM (scanning electron microscopy) characterization studies were done to evaluate the morphology of the powders. XRD analysis of the resulting powder confirmed the presence of crystalline α-Ce2Zr2O7 along with a Ce2Zr2O8 phase having a disordered fluorite cubic lattice. Phase composition, lattice parameters, and the atomic positions were also investigated. Refinement of XRD data was done to quantify the amount of α-Ce2Zr2O7 and Ce2Zr2O8 phases. Ni-base superalloy Inconel 625 was chosen as the coating substrate, and the powders were coated using an air plasma spraying (APS). A thermally grown oxide (TGO)/Al2O3 layer was observed owing to the high temperature of the substrate as well as the diffusion of bond coat material into the substrate. Coated samples were characterized by SEM to study the surface morphology, coating thickness, and interface microstructures. The thickness of the coated sample was found to be 400 μm. Thermal cycling test of the coated sample was carried out at 750°C for 50 h to evaluate the thermal shock resistance of the coating as well as the spalling behavior of the coating. Preliminary oxidation tests were carried out for 50 h at 750°C to evaluate the oxide growth by measuring weight gain of the oxide layers formed. Oxide growth signifies the gradual increment of layers over a period with a parabolic rate constant of about Kp= 1.18 × 10–3 mg2 cm–4 h–1.

Improvement in High Temperature Oxidation Resistance of Co-Al-W Based Superalloys

2015 ◽  
Vol 1760 ◽  
Author(s):  
Takahiko Ito ◽  
Shogo Ikeda ◽  
Katsushi Tanaka
Keyword(s):  
Weight Gain ◽  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Air Oxidation ◽  
Temperature Oxidation ◽  
Improve Oxidation Resistance

ABSTRACTOxidation tests of Cr containing Co-based superalloys with compositions of Co-20at.%Ni-9at.%Al-9at.%W-x at.%Cr (x = 2, 4, 6, 8 and 10) have been carried out at 1173 and 1273 K in air. Oxidation resistance is improved upon alloying with Cr not only at 1173 K but also at 1273 K. The weight gain of the 10at.%Cr alloy oxidized at 1173 K is similar to that of the 5th generation Ni-based superalloy of TMS-173. Alloying with Cr is efficient to improve oxidation resistance, however, the shape of γ’ precipitates is rounded and the alignment of the precipitates along the <100> direction becomes less pronounced upon alloying with Cr.

Molten Salt Synthesis of Chlorapatite Whiskers

2013 ◽  
Vol 668 ◽  
pp. 302-304 ◽  
Author(s):  
Ping Zhao ◽  
Tai Rong Zhao ◽  
Xue Hua Ren ◽  
Shuai Zhao ◽  
Kai Yang
Keyword(s):  
High Temperature ◽  
Molten Salt ◽  
Weight Ratio ◽  
Xrd Analysis ◽  
Molten Salt Synthesis ◽  
Molten Salt Method ◽  
Stoichiometric Mixture ◽  
Chemical Products

Chlorapatite whiskers were successfully prepared at 1250°C by the molten salt method. CaCl was the molten salt, CaCO3 and CaHPO4 were reactants, and then the ratio of molten salt to stoichiometric mixture was briefly studied. XRD and SEM were used to determine chemical products compound, and observe whiskers morphology. Results indicate that long and thin whiskers could be got, when the weight ratio of molten salt/ stoichiometric mixture is 1:1. Short and thick whiskers are corresponding to the ratio 1:2. Their compounds are both cholrapatite by XRD analysis. However when the ratio is 2:1, green transparent block not powder was got after sintering, which means molten salt is too much to become glass at the high temperature.

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