Hot corrosion behaviour of CNT-reinforced ZrO2-Y2O3 composite coatings on boiler tube steel at 900°C

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sandeep Kumar ◽  
Rakesh Bhatia ◽  
Hazoor Singh
Keyword(s):  
Molten Salt ◽  
Hot Corrosion ◽  
Corrosion Behaviour ◽  
Composite Coatings ◽  
Tube Steel ◽  
Boiler Tube ◽  
Protective Oxide ◽  
Corrosion Failure ◽  
Content Type ◽  
Boiler Tube Steel

Purpose In Indian thermal power plants, the main cause of boiler tube failure is the presence of molten sulphates and vanadates, which deteriorate the tube material at high temperatures. To combat the hot corrosion failure of metals, thermal spray technology is adopted. This study aims to investigate and study the effect of hot corrosion behaviour of carbon nanotube (CNT)-reinforced ZrO2-Y2O3 composite coatings on T-91 boiler tube steel in a molten salt environment at 900 °C for 50 cycles. Design/methodology/approach A plasma spray technique was used for development of the coatings. The samples were exposed to hot corrosion in a silicon tube furnace at 900 °C for 50 cycles. After testing, the test coupons were analysed by X-ray diffraction, scanning electron microscopy/energy dispersive spectroscopy and cross-sectional analysis techniques to aid understanding the kinetics of the corrosion reaction. Findings CNT-based reinforced coatings showed lower weight gain along with the formation of protective oxide scales during the experimentation. Improvement in protection against hot corrosion was observed with increase in CNT content in the coating matrix. Originality/value It is pertinent to mention here that the high temperature behaviour of CNT-reinforced ZrO2-Y2O3 composite on T-91 steel at 900°C temperature in molten salt environment has never been studied. Thus, the present research was conducted to provide useful results for the application of CNT-reinforced composite coatings at elevated temperature.

Hot corrosion behaviour of different Cr3C2–NiCr coatings on boiler tube steel at elevated temperature

2019 ◽  
Vol 16 (4) ◽  
pp. 452-459
Author(s):  
Karanjit Singh ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Molten Salt ◽  
Hot Corrosion ◽  
Corrosion Behaviour ◽  
Research Work ◽  
Tube Furnace ◽  
Tube Steel ◽  
Boiler Tube ◽  
Content Type ◽  
Boiler Tube Steel ◽  
Silicon Tube

Purpose This paper aims to investigate hot corrosion behaviour of different Cr3C2–NiCr coatings on boiler tube steel. Design/methodology/approach High velocity oxy fuel technique has been used to deposit different coatings on commercially available ASTM-SA213-T22 boiler tube steel. The hot corrosion studies have been performed in molten salt environment at 900°C temperature in silicon tube furnace in laboratory. Findings The results showed that uncoated superalloy suffered intense spalling and the weight change was massive during each cycle on studies of hot corrosion 900°C. The 100 per cent NiCr and 10 per cent (Cr3C2) – 90 per cent (NiCr) coatings provided better protection to T22 steel against the hot corrosion because of the formation of Ni and Cr3C2 layers. Originality/value In this research a variety of coatings have been used. This research work has been aimed to investigate the hot corrosion behavior of Boiler Steel b with different Cr3C2–NiCr coatings, under molten salt environment in Silicon tube furnace at 900°C, under cyclic conditions.

Experimental Analysis of Hot Corrosion Behaviour of some Composite Coatings on Boiler Steel at Elevated Temperature

2021 ◽  
Vol 41 ◽  
pp. 43-54
Author(s):  
Prince Puri ◽  
Khushdeep Goyal ◽  
Rakesh Goyal ◽  
Bal Krishan
Keyword(s):  
Hot Corrosion ◽  
Power Plants ◽  
Corrosion Behaviour ◽  
Composite Coatings ◽  
Thermal Power ◽  
Tube Steel ◽  
X Ray Diffraction ◽  
Boiler Steel ◽  
Boiler Tube Steel ◽  
Silicon Tube

Hot corrosion is the main reason of failure of boiler tubes used at high temperature in thermal power plants. This paper is an attempt to investigate the effect of different composite coatings on boiler tube steel in corrosive environment of Na2SO4 – 60%V2O5 at 900°C for 50 cycles. The coatings have been deposited with high velocity oxy fuel process. The samples were exposed to hot corrosion in a Silicon tube furnace at 900°C for 50 cycles. The kinetics of corrosion behaviour were analysed by the weight gain measurements after each cycle. Corrosion products were analysed with weight change statistics, X-ray diffraction, and scanning electron microscopy. It is found that 100Cr3C2 composite coatings provided the higher resistance to corrosion as compared to other types of coatings. Cr carbide layer was formed on the surface and these layers provided the protection from hot corrosion.

Mechanical and microstructural properties of carbon nanotubes reinforced chromium oxide coated boiler steel

2018 ◽  
Vol 15 (4) ◽  
pp. 429-439 ◽  
Author(s):  
Khushdeep Goyal ◽  
Hazoor Singh ◽  
Rakesh Bhatia
Keyword(s):  
Carbon Nanotubes ◽  
Composite Coatings ◽  
Tube Steel ◽  
Microstructural Properties ◽  
Boiler Tube ◽  
Boiler Steel ◽  
Content Type ◽  
X Ray ◽  
Boiler Tube Steel ◽  
Mechanical And Microstructural Properties

Purpose The purpose of this study was to fabricate carbon nanotubes (CNT)-reinforced chromium oxide coatings and investigate mechanical and microstructural properties of these newly developed coatings on the boiler tube steel. Design/methodology/approach 1 and 4 Wt.% CNT-reinforced Cr2O3 composite coatings were prepared and successfully deposited on ASTM-SA213-T22 (T22) boiler tube steel substrates using high-velocity oxy fuel (HVOF) thermal spraying method. Microhardness, porosity, metallography, X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy, cross-sectional elemental analysis and X-ray mapping analysis have been used to examine the coated specimens. Findings The porosity of the CNT-Cr2O3 composite coatings was found to be decreasing with the increases in CNT content, and hardness has been found to be increasing with increase in percentage of CNT in the composite coatings. The CNT were able to increase hardness by approximately 17 per cent. It was found that the CNT were uniformly distributed throughout Cr2O3 matrix. The CNT were found to be chemically inert during the spraying process. Originality/value It must be mentioned here that studies related to fabrication of HVOF sprayed CNT reinforced Cr2O3 composite coatings on T22 boiler tube steel are not available in the literature. Hence, present investigation can provide valuable information related to fabrication and properties of CNT reinforced coatings on boiler steel.

Improving the high-temperature oxidation resistance of ASME-SA213-T11 boiler tube steel by plasma spraying with CNT-reinforced alumina coatings

2018 ◽  
Vol 65 (2) ◽  
pp. 217-223 ◽  
Author(s):  
Rakesh Goyal ◽  
Buta Singh Sidhu ◽  
Vikas Chawla
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Composite Coatings ◽  
Tube Steel ◽  
Boiler Tube ◽  
Alumina Coatings ◽  
Temperature Oxidation ◽  
Content Type ◽  
Boiler Tube Steel

Purpose This paper aims to discuss that a conventional Al2O3, 1.5 Wt.% carbon nanotubes (CNTs)-Al2O3, 2 Wt.% CNTs-Al2O3 and 4 Wt.% CNTs-Al2O3 composite coatings were deposited with the help of Plasma spray process. Design/methodology/approach To better understand the effect of CNT reinforcement on oxidation resistance, high-temperature oxidation behaviour of conventional Al2O3, 1.5 Wt.% CNTs-Al2O3, 2 Wt.% CNTs-Al2O3 and 4 Wt.% CNTs-Al2O3 composite coatings at 900°C was compared with the performance of the uncoated ASME-SA213-T11 boiler tube steel substrate. Findings The results showed that the CNT-reinforced alumina coatings exhibited better oxidation resistance and thermal stability than uncoated ASME-SA213-T11 boiler tube steel. The coated steel substrates had a lower mass gain rate than the substrate after different oxidation times. Originality/value Limited literature is available where the CNT have been reinforced into the composite alloy powders and has been thermally spray-deposited for various surface engineering applications. This research showed that with the increase in the percentage of CNTs into the alloy powder mixture, there is a significant reduction in weight gain and hence higher resistance to oxidation.

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