Chromium Carbide Coatings for High Temperature Erosion Resistance

1996 ◽  
Author(s):  
D.R. Sielski ◽  
P. Sahoo
Keyword(s):  
High Temperature ◽  
Thermal Spray ◽  
Chromium Carbide ◽  
Power Plants ◽  
Life Cycles ◽  
Thermal Spray Coatings ◽  
Surface Protection ◽  
Spray Coatings ◽  
Carbide Coatings ◽  
Chromium Carbide Coatings

Abstract Escalating operation and maintenance costs and increasing intervals between outages place a heavy burden upon electric power producing components. To meet this demand, component life cycles must be extended with either material upgrades or utilization of surface protection products. This paper will discuss the experiences of the Tennessee Valley Authority in the application of thermal spray coatings and try to relate some of these experiences to component performance in fossil power plants' steam turbine components. The development of high velocity thermal spray processes has given coatings an advantage over the use of high priced material upgrades. Chromium carbide coatings have proven the most economical of the surface protection products for use in high temperature applications where solid particle erosion occurs. These coatings have received extensive laboratory testing where limited field results are now just becoming available. Various thermal spray coatings will be described. The development of newer coatings and laboratory test data will be discussed. Optical microscopy and wear studies will be included in the discussion. Where appropriate and available, comparisons to standard plasma sprayed coatings and uncoated substrata are made.

scholarly journals Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants: Part II—Effect of Environment and Outlook

2019 ◽  
Vol 28 (8) ◽  
pp. 1789-1850 ◽  
Author(s):  
Esmaeil Sadeghi ◽  
Nicolaie Markocsan ◽  
Shrikant Joshi
Keyword(s):  
High Temperature ◽  
Thermal Spray ◽  
Power Plants ◽  
High Temperature Corrosion ◽  
Thermal Spray Coatings ◽  
Current Status ◽  
Comprehensive Overview ◽  
Biomass Waste ◽  
Corrosion Resistant ◽  
Spray Coatings

Abstract High-temperature corrosion of critical components such as water walls and superheater tubes in biomass/waste-fired boilers is a major challenge. A dense and defect-free thermal spray coating has been shown to be promising to achieve a high electrical/thermal efficiency in power plants. The field of thermal spraying and quality of coatings have been progressively evolving; therefore, a critical assessment of our understanding of the efficacy of coatings in increasingly aggressive operating environments of the power plants can be highly educative. The effects of composition and microstructure on high-temperature corrosion behavior of the coatings were discussed in the first part of the review. The present paper that is the second part of the review covers the emerging research field of performance assessment of thermal spray coatings in harsh corrosion-prone environments and provides a comprehensive overview of the underlying high-temperature corrosion mechanisms that lead to the damage of exposed coatings. The application of contemporary analytical methods for better understanding of the behavior of corrosion-resistant coatings is also discussed. A discussion based on an exhaustive review of the literature provides an unbiased commentary on the advanced accomplishments and some outstanding issues in the field that warrant further research. An assessment of the current status of the field, the gaps in the scientific understanding, and the research needs for the expansion of thermal spray coatings for high-temperature corrosion applications is also provided.

scholarly journals Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants. Part I: Effect of Composition and Microstructure

2019 ◽  
Vol 28 (8) ◽  
pp. 1749-1788 ◽  
Author(s):  
Esmaeil Sadeghi ◽  
Nicolaie Markocsan ◽  
Shrikant Joshi
Keyword(s):  
High Temperature ◽  
Thermal Spray ◽  
Power Plants ◽  
Corrosion Damage ◽  
Clean Energy ◽  
High Temperature Corrosion ◽  
Thermal Spray Coatings ◽  
Corrosion Resistant ◽  
Spray Coatings ◽  
Corrosion Resistant Coatings

Abstract Power generation from renewable resources has attracted increasing attention in recent years owing to the global implementation of clean energy policies. However, such power plants suffer from severe high-temperature corrosion of critical components such as water walls and superheater tubes. The corrosion is mainly triggered by aggressive gases like HCl, H2O, etc., often in combination with alkali and metal chlorides that are produced during fuel combustion. Employment of a dense defect-free adherent coating through thermal spray techniques is a promising approach to improving the performances of components as well as their lifetimes and, thus, significantly increasing the thermal/electrical efficiency of power plants. Notwithstanding the already widespread deployment of thermal spray coatings, a few intrinsic limitations, including the presence of pores and relatively weak intersplat bonding that lead to increased corrosion susceptibility, have restricted the benefits that can be derived from these coatings. Nonetheless, the field of thermal spraying has been continuously evolving, and concomitant advances have led to progressive improvements in coating quality; hence, a periodic critical assessment of our understanding of the efficacy of coatings in mitigating corrosion damage can be highly educative. The present paper seeks to comprehensively document the current state of the art, elaborating on the recent progress in thermal spray coatings for high-temperature corrosion applications, including the alloying effects, and the role of microstructural characteristics for understanding the behavior of corrosion-resistant coatings. In particular, this review comprises a substantive discussion on high-temperature corrosion mechanisms, novel coating compositions, and a succinct comparison of the corrosion-resistant coatings produced by diverse thermal spray techniques.

Investigation into the Effects of High Temperature on Mechanical Properties of Thermal Spray Coatings Applied by Plasma Spraying

2018 ◽  
Vol 284 ◽  
pp. 1151-1156
Author(s):  
Lenar N. Shafigullin ◽  
A.R. Ibragimov ◽  
A.I. Saifutdinov
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Temperature ◽  
Thermal Spray ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Thermal Spray Coatings ◽  
Spray Coatings ◽  
Heat Treatment Of Coatings ◽  
Double Heat Treatment

C. C. Berndt advanced investigations of mechanical properties of thermal spray coatings under 4-point bending. He found that this investigation method is sensitive to the mechanical properties of thermal spray coatings.This paper contains the detailed investigation results for thermal spray coatings of zirconium dioxide under 4-point bending, i.e. tests of the specimens subjected to spraying at varying conditions and pre-test soaking with the various duration at 1100 °С.It was established how the mechanical properties of thermal spray coatings changed depending on the spraying mode and high temperature soaking. The test results show that the double heat treatment of coatings is more preferable than one-time heat treatment as it make the properties change linearly. It is more easily controllable during operation of the components with thermal spray coating.

Image-Based Modeling for Assessing Thermal Conductivity of Thermal Spray Coatings at Ambient and High Temperature

2006 ◽  
Author(s):  
Y. Tan ◽  
A. Sharma ◽  
J. P. Longtin ◽  
S. Sampath ◽  
H. Wang
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Thermal Spray ◽  
Process Parameters ◽  
Thermal Spraying ◽  
Thermal Spray Coatings ◽  
Analysis Model ◽  
Element Analysis ◽  
Spray Coatings ◽  
Coating Microstructure

Thermal spray coatings are used extensively for protection of engineering components and structures in a variety of applications. Due to the nature of thermal spraying process, the coating thermal, mechanical, and electrical properties depend strongly on the coating microstructure, which consists of many individual splats, interfaces between the splats, defects and voids. The coating microstructure, in turn, is determined by the thermal spray process parameters. In order to relate coating process parameters to the final coating performance, then, it is desirable to relate coating microstructure to coating properties. In this work, thermal conductivity is used as the physical parameter of interest. Thermal conductivity of thermal spray coatings is studied by using an image analysis-based approach of typical coating cross sections. Three coating systems, yttria stabilized zirconia (YSZ), molybdenum, and Ni-5wt.%Al are explored in this work. For each material, thermal conductivity is simulated by using a microstructure image-based finite element analysis model. The model is then applied to high temperature conditions (up to 1200 °C) with a hot stage-equipped scanning electron microscope imaging technique to assess thermal conductivity at high temperatures. The coating thermal conductivity of metallic coatings is also experimentally measured by using a high-temperature laser flash technique.

scholarly journals Duplex Al-based thermal spray coatings for corrosion protection in high temperature refinery applications

2004 ◽  
Vol 7 (1) ◽  
pp. 189-194 ◽  
Author(s):  
Adriana da Cunha Rocha ◽  
Fernando Rizzo ◽  
Chaoliu Zeng ◽  
Marcelo Piza Paes
Keyword(s):  
High Temperature ◽  
Corrosion Protection ◽  
Thermal Spray ◽  
Thermal Spray Coatings ◽  
Spray Coatings

High-Temperature Sulfidation of Fe3Al Thermal Spray Coatings at 600°C

CORROSION ◽  
2000 ◽  
Vol 56 (2) ◽  
pp. 189-198 ◽  
Author(s):  
K. R. Luer ◽  
J. N. DuPont ◽  
A. R. Marder
Keyword(s):  
High Temperature ◽  
Thermal Spray ◽  
Thermal Spray Coatings ◽  
Spray Coatings

Fatigue Life in Bending and Coatings Residual Stress in Tungsten Carbide Thermal Spray Coatings

1997 ◽  
Author(s):  
R.T.R. McGrann ◽  
J.R. Shadley ◽  
E.F. Rybicki ◽  
D.J. Graving ◽  
B.E. Badger ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Tungsten Carbide ◽  
Thermal Spray ◽  
Thermal Spray Coatings ◽  
Chrome Plating ◽  
Spray Coatings ◽  
Wear Protection ◽  
Carbide Coatings ◽  
Flat Beam

Abstract Tungsten caibide (WC) thermal spray coatings are being used for wear protection on selected components of aircraft. Tungsten carbide coatings are being used on aircraft flap tracks and fan and compressor blade mid-span dampers. However, a larger use of tungsten carbide coatings is being considered for other commercial aircraft applications where it would be used as a replacement for chrome plating. For instance, WC coatings are currently being tested on aircraft landing gear parts. One factor that affects the suitability of WC coatings for these applications is the fatigue life of the coated part. Coatings, whether chrome plating or thermal spray coating, can reduce the fatigue life of the part compared to an uncoated part. This study compares the fatigue life of uncoated 6061 aluminum specimens to the fatigue life of WC thermal sprayed coated 6061 aluminum specimens. The relation between the residual stress level in the coating and the fatigue life of the specimens is also investigated. Fatigue tests were run on cantilever flat beam specimens that were coated on one side. Specimens were cycled in bending so that the coatings experienced tensile fatigue stresses. Residual stress levels for each type of coating were determined using the Modified Layer Removal Method on specimens processed along with the cantilever flat beam specimens. Test results show that the fatigue life of the WC coated specimens is directly related to the level of compressive residual stress in the coating.

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