Some Observations Regarding Erosion-Corrosion Performance of HVOF-Sprayed Cr3C2- NiCr and Cr3C2- NiCr-(25) WC-Co Coatings in Actual Boiler Environment

2007 ◽  
Vol 26-28 ◽  
pp. 1345-1348 ◽  
Author(s):  
Manpreet Kaur ◽  
Harpreet Singh ◽  
Satya Prakash
Keyword(s):  
Weight Change ◽  
Thermal Power ◽  
Coated Steel ◽  
Oxide Scales ◽  
Corrosion Performance ◽  
Boiler Steel ◽  
X Ray ◽  
Uncoated Steel ◽  
Erosion Corrosion ◽  
Boiler Environment

Cr3C2- NiCr and Cr3C2- NiCr-(25) WC-Co coatings were deposited on T22 boiler steel by High Velocity Oxy-Fuel (HVOF) Technology. The coated as well as the uncoated steel samples were exposed to the actual boiler environments in a thermal power plant for 1500 hrs under cyclic conditions to evaluate their erosion-corrosion performance. Weight change measurements were taken for each sample after every 100 hrs. It has been observed that the weight change trends for coated steel with Cr3C2- NiCr and Cr3C2- NiCr-(25) WC-Co coatings followed a parabolic trend. The exposed samples were physically investigated for any macroscopic changes after each cycle of 100 hours. The uncoated steel showed blisters and spallation of its oxide scale, whereas the coated samples exhibited intact oxide scales, in general. Scanning Electron Microscopy/Energy Dispersive X-Ray Analysis (SEM/EDAX) was done to characterize morphology of the oxide scales. The protective nature of coatings has been explained based on the results of the study.

Studies on erosion-corrosion behaviour of plasma sprayed Ni3Al coating in a coal-fired thermal power plant environment at 540°C

2017 ◽  
Vol 64 (5) ◽  
pp. 540-549 ◽  
Author(s):  
S.B. Mishra ◽  
Kamlesh Chandra ◽  
Satya Prakash
Keyword(s):  
Power Plant ◽  
Thermal Power Plant ◽  
Nickel Aluminide ◽  
Corrosion Behaviour ◽  
Thermal Power ◽  
Content Type ◽  
Erosion Corrosion ◽  
Boiler Environment ◽  
Plasma Sprayed ◽  
Al Coating

Purpose The purpose of this study is to investigate the application of Ni3Al coating for boilers and other power plant equipment, which suffer severe erosion-corrosion problems resulting in substantial losses. Currently, superalloys are being used to increase the service life of the boilers. Although the superalloys have adequate mechanical strength at elevated temperature, they often lack resistance to erosion-corrosion environments. Design/methodology/approach In this paper, the erosion-corrosion performance of plasma-sprayed nickel aluminide (Ni3Al) coating on nickel- and iron-based superalloys have been evaluated by exposing them to the low temperature primary superheater zone of the coal-fired thermal power plant at the temperature zone of 540°C for ten cycles of 100 h duration. The exposed products were analysed along the surface and cross-section using scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron micro probe analysis (EPMA). Findings The XRD, SEM and EPMA analyses have shown the formation of mainly NiO, NiAl2O4 and indicated the presence of Ni3Al, Ni and Al2O3. In the boiler environment, Ni3Al coating partially oxidizes and acts as a perfect barrier against erosion-corrosion of superalloys. The partially oxidised Ni3Al coating remains intact even after 1,000 h cycle exposure. Originality/value The probable mechanism of attack for the plasma-sprayed Ni3Al coating in the given boiler environment is presented.

scholarly journals PERFORMANCE OF NI3AL AND TIO2 COATINGS ON T22 BOILER TUBE STEEL IN SIMULATED BOILER ENVIRONMENT IN LABORATORY

2017 ◽  
Vol 46 (1) ◽  
pp. 54-61 ◽  
Author(s):  
Simranjeet Singh ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Thermal Power ◽  
Steel Tube ◽  
Tube Steel ◽  
Operating Life ◽  
Boiler Steel ◽  
Thermo Gravimetric ◽  
Corrosion Studies ◽  
Boiler Tube Steel ◽  
Boiler Environment ◽  
Kinetics Of

The corrosion of boiler steel tube in coal fired boiler is main matter during design and operation of thermal power plant and it leads to both direct and indirect cost and energy lost, including losses due to plant shut down time and inefficiency of operation. One of the feasible solution to solve the problem is providing surface coating on boiler steel tube, which on one hand protect the tube from highly corrosive flue gaseous and on other hand increase their operating life. Ni3Al and TiO2 and coatings were sprayed on ASTM SA213-T22 steel by using the HVOF process. Hot corrosion studies were conducted on the uncoated as well as coated sprayed specimens in molten salt environment of Na2SO4-60%V2O5 at 900ºC for 50 cycles. In the experiment each cycle consist of 1 hr of heating in tube furnace followed by 20 minute of cooling in air. The thermo-gravimetric technique was used in order to establish the kinetics of corrosion. XRD, SEM/EDS testing were used to examine the corrosion specimens. Theresult shows that both the coated samples are beneficial to corrosion resistance over uncoated samples. TiO2 coating was found to be most protective followed by the Ni3Al coating.

scholarly journals WC-Co and WC-Co-Cr Coatings for the Protection of API Pipeline Steel from Corrosion in 4% NaCl Solution

Coatings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 275
Author(s):  
El-Sayed M. Sherif ◽  
Magdy M. El Rayes ◽  
Hany S. Abdo
Keyword(s):  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Corrosion Current ◽  
Coated Steel ◽  
Cathodic Current ◽  
X Ray ◽  
Inorganic Coatings ◽  
Uncoated Steel ◽  
Cyclic Potentiodynamic Polarization ◽  
Fuel Deposition

Two inorganic coatings, namely 88%WC-12%Co (PSC1) and 86%WC-10%Co-4%Cr (PSC2), were deposited on the surface of an API-2H pipeline steel using high velocity oxy-fuel deposition. The corrosion of the uncoated and coated API-2H steel after their immersion in a solution of 4.0% NaCl for 1 h, 24 h, and 48 h has been studied. Various electrochemical measurements such cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and potentiostatic current versus time were employed. The surface morphology and analysis were carried out via the use of scanning electron microscopy and energy dispersive X-ray examinations. All experiments have revealed that the deposited coatings decreased the cathodic current, anodic current, corrosion current density (jCorr), absolute current versus time, and the corrosion rate (RCorr) compared to the uncoated API-2H steel. The value of jCorr decreased from 47 µA/cm2 for uncoated steel to 38 µA/cm2 for the PSC1-coated steel and 29 µA/cm2 for the PSC2-coated steel. Moreover, prolonging the time of exposure decreases the jCorr and RCorr values. The jCorr values obtained after 48 h recorded 32, 26, and 20 µA/cm2 for the uncoated, PSC1, and PSC2 samples, respectively. Moreover, applying these coatings also led to increasing the corrosion resistance (RP) after all the exposure periods of time. In addition, the PSC2 coating was found to be more protective against corrosion for the surface of the steel than the PSC1 coating.

Improving the hot corrosion resistance of boiler tube steels by detonation gun sprayed coatings in actual boiler of thermal power plant

2019 ◽  
Vol 66 (4) ◽  
pp. 394-402
Author(s):  
Vikramjit Singh ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Power Plants ◽  
Thermal Power ◽  
Boiler Steel ◽  
Content Type ◽  
Boiler Environment ◽  
Detonation Gun ◽  
Sprayed Coatings

Purpose This paper aims to investigate the hot corrosion behavior of Ni-Cr and Cr3C2-NiCr coatings, deposited on T11, P91 boiler steels by detonation gun spray coating (D-Gun) process to enhance high temperature corrosion resistance. Design/methodology/approach Hot corrosion studies were conducted in secondary super heater zone of boiler at 900 °C for 10 cycles on bare and D-Gun coated steel specimens. The microhardness and porosity values of as-sprayed coatings were measured before exposing the specimens in the boiler environment. Each cycle consisted 100 h of heating in the boiler environment followed by 20 min of cooling in air. The weight change measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. X-ray diffraction, SEM techniques were used to analyze the corroded specimens. Findings Uncoated boiler steel experienced higher weight loss. The Cr3C2-NiCr coating was found to be more protective than Ni-Cr coating. The phases revealed the formation of oxide scale on coated specimens, mainly consist of nickel and chromium, which are reported to be protective against the hot corrosion. Originality/value There is very limited reported literature on hot corrosion behavior of Ni-Cr and Cr3C2-NiCr coatings deposited on the T11 and P91 substrates by detonation gun (D-gun) spray technique. T11 and P91 alloy steels have been chosen for this study because these two alloys are used to manufacture boiler tubes used in Indian thermal power plants.

scholarly journals Preparation of Synthetic Zeolites from Coal Fly Ash by Hydrothermal Synthesis

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1267
Author(s):  
David Längauer ◽  
Vladimír Čablík ◽  
Slavomír Hredzák ◽  
Anton Zubrik ◽  
Marek Matik ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Product Analysis ◽  
Coal Combustion Products ◽  
X Ray ◽  
Wide Range ◽  
Silica Alumina

Large amounts of coal combustion products (as solid products of thermal power plants) with different chemical and physical properties cause serious environmental problems. Even though coal fly ash is a coal combustion product, it has a wide range of applications (e.g., in construction, metallurgy, chemical production, reclamation etc.). One of its potential uses is in zeolitization to obtain a higher added value of the product. The aim of this paper is to produce a material with sufficient textural properties used, for example, for environmental purposes (an adsorbent) and/or storage material. In practice, the coal fly ash (No. 1 and No. 2) from Czech power plants was firstly characterized in detail (X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), particle size measurement, and textural analysis), and then it was hydrothermally treated to synthetize zeolites. Different concentrations of NaOH, LiCl, Al2O3, and aqueous glass; different temperature effects (90–120 °C); and different process lengths (6–48 h) were studied. Furthermore, most of the experiments were supplemented with a crystallization phase that was run for 16 h at 50 °C. After qualitative product analysis (SEM-EDX, XRD, and textural analytics), quantitative XRD evaluation with an internal standard was used for zeolitization process evaluation. Sodalite (SOD), phillipsite (PHI), chabazite (CHA), faujasite-Na (FAU-Na), and faujasite-Ca (FAU-Ca) were obtained as the zeolite phases. The content of these zeolite phases ranged from 2.09 to 43.79%. The best conditions for the zeolite phase formation were as follows: 4 M NaOH, 4 mL 10% LiCl, liquid/solid ratio of 30:1, silica/alumina ratio change from 2:1 to 1:1, temperature of 120 °C, process time of 24 h, and a crystallization phase for 16 h at 50 °C.

scholarly journals Influence of the Nb and V Addition on the Microstructure and Corrosion Resistance of the Fe-B-Co-Si Alloy

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4045
Author(s):  
Rafał Mech ◽  
Jolanta Gąsiorek ◽  
Amadeusz Łaszcz ◽  
Bartosz Babiarczuk
Keyword(s):  
Corrosion Resistance ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Significant Influence ◽  
Corrosion Performance ◽  
X Ray ◽  
Final Performance ◽  
Differential Calorimeter ◽  
Comparison Of The Results ◽  
Scanning Electron

The paper presents a comparison of the results of the corrosion resistance for three Fe-B-Co-Si-based newly developed alloys with the addition of Nb and V. The corrosion performance differences and microstructure variations were systematically studied using scanning electron microscope, electric corrosion equipment, X-ray diffractometer, and differential calorimeter. It has been shown that each alloying addition increased the corrosion resistance. The highest corrosion resistance obtained by potentiodynamic polarization was found for the alloy with both Nb and V addons (Fe57Co10B20Si5Nb4V4) and lowest in the case of the basic four-element Fe62Co15B14Si9 material. This shows that the proper choice of additions is of significant influence on the final performance of the alloy and allows tailoring of the material for specific applications.

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