Electrochemical monitoring of high-temperature molten-salt corrosion

1990 ◽  
Vol 33 (1-2) ◽  
pp. 79-94 ◽  
Author(s):  
G. Gao ◽  
F. H. Stott ◽  
J. L. Dawson ◽  
D. M. Farrell
Keyword(s):  
High Temperature ◽  
Molten Salt ◽  
Salt Corrosion ◽  
Electrochemical Monitoring

Electrochemical Studies on High-Temperature Corrosion of Silicon-Iron Coatings and Iron Aluminide Intermetallic Alloys by Molten Salts

CORROSION ◽  
2001 ◽  
Vol 57 (6) ◽  
pp. 489-496 ◽  
Author(s):  
M. Amaya ◽  
J. Porcayo-Calderon ◽  
L. Martinez
Keyword(s):  
High Temperature ◽  
Molten Salt ◽  
Electric Power ◽  
Molten Salts ◽  
Corrosion Current ◽  
High Temperature Corrosion ◽  
Iron Aluminide ◽  
Fuel Oil ◽  
Silicon Iron ◽  
Salt Corrosion

Abstract The performance of Fe-Si coatings and an iron aluminide (FeAl) intermetallic alloy (FeAl40at%+0.1at%B+10vol%Al2O3) in molten salts containing vanadium pentoxide (V2O5) and sodium sulfate (Na2SO4) is reported. Corrosion and fouling by ash deposits containing V2O5 and Na2SO4 are typical corrosion problems in fuel oil-fired electric power units. High-temperature corrosion tests were performed using both electrochemical polarization and immersion techniques. The temperature interval of this study was 600°C to 900°C, and the molten salts were 80wt%V2O5-20wt%Na2SO4. Curves of corrosion current density vs temperature obtained by the potentiodynamic studies are reported, as well as the weight loss vs temperature curves from molten salt immersion tests. Both Fe-Si coatings and FeAl40at%+0.1at%B+10vol%Al2O3 showed good behavior against molten salt corrosion. The final results show the potential of these coatings and alloys to solve the high-temperature corrosion in fuel oil-fired electric power units.

Development of High Temperature, Corrosion Resistant Sensors for Concentrating Solar Power Systems

2014 ◽  
Author(s):  
Michael W. Usrey ◽  
Yiping Liu ◽  
Mark Anderson ◽  
Jon Lubbers ◽  
Brady Knowles ◽  
...  
Keyword(s):  
High Temperature ◽  
Molten Salt ◽  
Solar Power ◽  
Thermal Flux ◽  
Temperature Cycling ◽  
Chloride Salt ◽  
Concentrating Solar Power ◽  
Salt Corrosion ◽  
Chloride Salts ◽  
Functional Ceramics

Solar power is a sustainable resource which can reduce the power generated by fossil fuels, lowering greenhouse gas emissions and increasing energy independence. The U.S. Department of Energy’s SunShot Initiative has set goals to increase the efficiency of concentrating solar power (CSP) systems. One SunShot effort to help CSP systems exceed 50% efficiency is to make use of high-temperature heat transfer fluids (HTFs) and thermal energy storage (TES) fluids that can increase the temperature of the power cycle up to 1300°C. Sporian has successfully developed high-temperature operable pressure, temperature, thermal flux, strain, and flow sensors for gas path measurements in high-temperature turbine engines. These sensors are based on a combination of polymer derived ceramic (PDC) sensors, advanced high-temperature packaging, and integrated electronics. The overall objective is the beneficial application of these sensors to CSP systems. Through collaboration with CSP industry stakeholders, Sporian has established a full picture of operational, interface, and usage requirements for trough, tower, and dish CSP architectures. In general, sensors should have accurate measurement, good reliability, reasonable cost, and ease of replacement or repair. Sensors in contact with hot salt HTF and TES fluids will experience temperature cycling on a daily basis, and parts of the system may be drained routinely. Some of the major challenges to high-temperature CSP implementation include molten salt corrosion and flow erosion of the sensors. Potential high-temperature sensor types that have been identified as of interest for CSP HTF/TES applications include temperature, pressure, flow, and level sensors. Candidate solar salts include nitrate, carbonate, and chloride, with different application temperatures ranging from 550°C-900°C. Functional ceramics were soaked for 500 hours in molten nitrate, carbonate, and chloride salts, showing excellent corrosion resistance in chloride salts and good resistance in nitrate salts. The demonstration of functional ceramics in relevant HTFs laid the foundation for full prototype sensor and packaging demonstration. Sporian has developed a packaging approach for ceramic-based sensors in various harsh gaseous environments at temperatures up to 1400°C, but several aspects of that packaging are not compatible with corrosive and electrically conductive HTFs. In addition to consulting published literature, a 300 hour soak test in molten chloride salt allowed the authors to identify suitable structural metals and ceramics. Based on discussions with stakeholders, molten salt corrosion testing and room-temperature water flow testing, suitable for CSP sensor/packaging concepts were identified for future development, and initial prototypes have been built and tested.

A Study on Thermal Spray Coatings of Recuperators

1996 ◽  
Author(s):  
B.G. Seong ◽  
S.Y. Hwang
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Molten Salt ◽  
High Temperature Corrosion ◽  
Maximum Temperature ◽  
Corrosion Mechanism ◽  
Spray Coatings ◽  
Arc Spray ◽  
Salt Corrosion ◽  
Hvof Spray

Abstract High temperature corrosion is a serious problem on tlie heat exchanger tubes of recuperators because they encounter an corrosive environment at maximum temperature around 900°C. These tubes were found to be corroded via oxidation, sulfidation and molten salt corrosion. Particularly molten salt corrosion could be the most severe corrosion mechanism. As a protective coating for recuperators, nickel and cobalt based self-fluxing alloys, iron based amorphous alloy and chromium carbide cermet coatings were considered. These coatings were prepared by an arc spray and or/not fusing or a HVOF spray. Their molten salt corrosion resistance was tested, and the high temperature corrosion resistance in a SO2 containing atmosphere was examined. Also microstructures of the coatings were studied after corrosion tests.

Stress Evolution and Element Diffusion in Bi-Layered Yb2SiO5/ Mullite Environmental Barrier Coatings under High-Temperature Molten Salt Corrosion

2018 ◽  
Vol 281 ◽  
pp. 478-486
Author(s):  
Hong Fei Chen ◽  
Ya Xiong Du ◽  
Juan Feng ◽  
Guang Yang ◽  
Yan Feng Gao
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Molten Salt ◽  
Corrosion Mechanism ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Substrate Interface ◽  
Layered Coatings ◽  
Salt Corrosion

Yb2SiO5/mullite bi-layered coatings are promising environmental barrier coatings, but its molten salt corrosion mechanism is unclear. In this work, Yb2SiO5/mullite bi-layered coatings are fabricated by combining plasma spraying and dip-coating techniques. Residual stresses in the coatings caused by thermo-mechanical interaction are investigated by a nondestructive Raman spectrum method under high-temperature molten salt corrosion. In the as-deposited coatings, the stress in the mullite layer is compressive and the value near Si3N4 substrate is minimum. During high-temperature corrosion test, the residual stress near mullite-substrate interface changes sharply while the stress near mullite-Yb2SiO5 interface is concentrated without large fluctuation. An interfacial phase, YbAlO3, which is formed because of the inter diffusion of Al in the mullite layer and Yb in the Yb2SiO5 layer, causes the stress concentration. The change of SiO2 component in the mullite layer leads to the sharp change of residual stress near the mullite-substrate interface.

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