High-Temperature Corrosion in Gas Turbines and Steam Boilers by Fuel Impurities. I. Measurement of Nickel Alloy Corrosion Rate in Molten Salts by Linear Polarization Technique

1972 ◽  
Vol 11 (4) ◽  
pp. 438-443 ◽  
Author(s):  
W. R. May ◽  
M. J. Zetlmeisl ◽  
Lewis Bsharah ◽  
R. R. Annand
Keyword(s):  
High Temperature ◽  
Corrosion Rate ◽  
Nickel Alloy ◽  
Linear Polarization ◽  
Gas Turbines ◽  
Molten Salts ◽  
High Temperature Corrosion ◽  
Polarization Technique ◽  
Steam Boilers

High-Temperature Corrosion in Gas Turbines and Steam Boilers by Fuel Impurities—Part V: Lead Containing Slags

1975 ◽  
Vol 97 (3) ◽  
pp. 441-447 ◽  
Author(s):  
M. J. Zetlmeisl ◽  
W. R. May ◽  
R. R. Annand
Keyword(s):  
High Temperature ◽  
Linear Polarization ◽  
Gas Turbines ◽  
Sodium Level ◽  
High Temperature Corrosion ◽  
Corrosion Rates ◽  
Polarization Technique ◽  
Steam Boilers

The effect of lead on the corrosivity and friability of slags containing various ratios of sodium, vanadium, magnesium, and silicon has been evaluated. The application of the linear polarization technique was demonstrated. Lead produces very corrosive melts and tenacious slags. Magnesium will inhibit corrosion to acceptable levels and produce friable slags at 800 °C with a 4 to 1 ratio of additive to vanadium plus lead and a sodium to vanadium plus lead ratio no greater than 0.1. To produce friable slags at 900°, sodium must first be reduced to a sodium to vanadium plus lead ratio of 0.01. Second, a magnesium-silicon additive must be used at a 6 to 1 ratio of additive to vanadium plus lead. The corrosion rates of lead containing melts increases rapidly with sodium level.

Environmental Effects on the High-Temperature Corrosion of Superalloys in Present and Future Gas Turbines

1972 ◽  
Vol 94 (2) ◽  
pp. 149-153 ◽  
Author(s):  
S. Y. Lee ◽  
W. E. Young ◽  
C. E. Hussey
Keyword(s):  
High Temperature ◽  
Corrosion Rate ◽  
Surface Temperature ◽  
Gas Turbines ◽  
Critical Factor ◽  
High Temperature Corrosion ◽  
Operating Conditions ◽  
Dynamic Type ◽  
Type Test ◽  
Effects Of Temperature

Effects of temperature and contaminant levels on the high-temperature corrosion of superalloys used in gas turbines were investigated using pressurized passages which simulate the operating conditions of present-day gas turbines. The alloys were tested in a cooled configuration realistically simulating the air-cooled vanes and blades of a gas turbine. Conclusions are drawn as to the permissible level of contaminants and the effect of metal cooling on high-temperature corrosion. It is shown that the surface temperature of a blade or vane rather than the gas-stream temperature is the critical factor in determining the amount of attack to be expected at a given contaminant level and the amount of attack is an exponential function of this temperature. Furthermore, in a dynamic-type test no decrease in corrosion rate is noted at higher temperatures. It was concluded that the use of a 5 ppm Na/2 ppm V fuel would result in an excessive amount of attack with a metal surface temperature of 1500 deg F.

High-Temperature Corrosion in Gas Turbines and Steam Boilers by Fuel Impurities—Part VII: Evaluation of Magnesium-Aluminum-Silicon Combinations as Corrosion Inhibitors

1976 ◽  
Vol 98 (4) ◽  
pp. 511-516 ◽  
Author(s):  
W. R. May ◽  
M. J. Zetlmeisl ◽  
R. R. Annand
Keyword(s):  
High Temperature ◽  
Linear Regression ◽  
Corrosion Inhibitor ◽  
Gas Turbines ◽  
Corrosion Inhibitors ◽  
High Temperature Corrosion ◽  
Regression Analyses ◽  
Stepwise Linear Regression ◽  
Fuel Ash ◽  
Steam Boilers

Aluminum, alone and in several combinations with magnesium and silicon, has been evaluated as a corrosion inhibitor and slag modifier for heavy fuel ash. Stepwise linear regression analyses were carried out on the data and the results are compared with earlier data on magnesium and silicon. The Mg-Al-Si combination gives superior tolerance to aggravation of corrosion caused by sodium. It gives the slag a friability equivalent to Mg-Si combinations.

High-Temperature Corrosion in Gas Turbines and Steam Boilers by Fuel Impurities: IV—Evaluation of Silicon and Magnesium-Silicon as Corrosion Inhibitors

1974 ◽  
Vol 96 (2) ◽  
pp. 124-128 ◽  
Author(s):  
W. R. May ◽  
M. J. Zetlmeisl ◽  
R. R. Annand
Keyword(s):  
High Temperature ◽  
Magnesium Sulfate ◽  
Vanadium Pentoxide ◽  
Sodium Sulfate ◽  
Gas Turbines ◽  
Corrosion Inhibitors ◽  
High Temperature Corrosion ◽  
Corrosion Rates ◽  
Steam Boilers

The corrosion rates of Udimet™ 500 in a variety of sodium sulfate-silica-vanadium pentoxide and sodium sulfate-magnesium sulfate-silica-vanadium pentoxide slag compositions were measured electrochemically at temperatures up to 950 deg. The weight ratios of the elements, sodium, silicon, and magnesium to vanadium were defined for acceptable corrosion rates. A simple burner test for slag evaluation is described. Characteristics of slags produced by magnesium, silicon, and magnesium-silicon in conjunction with sodium sulfate and vanadium pentoxide are discussed. Results indicate that the magnesium-silicon combination produces a slag which is equally as low as magnesium in corrosivity and superior in slag characteristics.

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.

High-Temperature Corrosion of Ni3Al+ 2.9%Cr Alloy in Ar-0.2%SO2 Gas

2018 ◽  
Vol 775 ◽  
pp. 441-447
Author(s):  
Dong Bok Lee ◽  
Min Jung Kim ◽  
Gyu Chul Cho ◽  
Soon Young Park ◽  
Poonam Yadav
Keyword(s):  
High Temperature ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Kirkendall Effect ◽  
High Temperature Corrosion ◽  
Scale Spallation ◽  
Corrosion Tests ◽  
Cooling Period ◽  
Corrosion Kinetics ◽  
Period 2

The high-temperature corrosion behavior of Ni3Al+2.9 wt% Cr alloy was studied in SO2-containing environment. Corrosion tests were carried out at 900, 1000, and 1100 °C for 100 h in atmospheric Ar-0.2% SO2 gas. The alloy corroded relatively slowly due mainly to formation of Al2O3 in the scale. Its corrosion kinetics deviated from the parabolic corrosion rate law to a certain extent owing to ensuing scale spallation. This was attributed to (1) stress generated during scaling and the subsequent cooling period, (2) voids that formed due to the Kirkendall effect, and (3) incorporation of sulfur in the scale. The scale that formed after corrosion at 900 °C consisted of the outer NiO scale, middle NiAl2O4 scale, and inner Al2O3 scale. The increased corrosion rate at 1000 and 1100 °C led to formation of the outer NiO scale, and inner Al2O3 scale.

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