The high-temperature corrosion behavior of Nb-Al alloys in a H2/H2S/H2O gas mixture

1997 ◽  
Vol 48 (5-6) ◽  
pp. 439-469 ◽  
Author(s):  
W. Kai ◽  
R. T. Huang
1994 ◽  
Vol 364 ◽  
Author(s):  
H. Li ◽  
J. T. Guo ◽  
W. H. Lai ◽  
S. H. Wang ◽  
M. H. Tan

AbstractThe corrosion behavior of a Ni3A1–1 5at%Fe alloy has been studied in air and melted salts, and also that of Ni3Al alloys contained series boron in melted salts. The first alloy has two oxidation rate constants. Its initial oxidation activity energy is 319 kJ / mol. There was much FeAl2O4 formed at 950°C, which possessed better oxidation resistance than NiFe2O4, therefore the alloy had the best oxidation resistance at 950°C. It also had better sulfidation resistance than 00Cr19NillTi stainless steel at 850°C, but the alloy was sulfidized seriously at 950°C. The sulfides were FeS2 at 850°C and A12S3, Ni2S3 at 950°C. There were different initial oxides formed, which were Fe3O4 at 850°C, and mixture oxides of NiO, NiMoO4, A12O3 and NiAl2O4 at 950°C , respectively. The Ni3Al alloys with boron contents from 0 to 3.7at% had better sulfidation resistance than the stainless steel at 850°C, and the alloy with 1.37at%B was the best. The sulfides were the same in the boron containing Ni3Al alloys which were Al2S3 and Ni7S6.


2011 ◽  
Vol 696 ◽  
pp. 272-277 ◽  
Author(s):  
Toto Sudiro ◽  
Tomonori Sano ◽  
Akira Yamauchi ◽  
Shoji Kyo ◽  
Osamu Ishibashi ◽  
...  

The objective of this study is to develop an excellent corrosion resistant alloy for high temperature coating applications. The Si-containing alloys consisting of CoNiCrAlY and CrSi2 alloys with varying Si and Ni content respectively were prepared by spark plasma sintering (SPS) technique. The corrosion behavior of these alloys was investigated in the gas phase of air-(Na2SO4+25.7mass%NaCl) at elevated temperatures of 923, 1073 and 1273K. The results showed that CoNiCrAlY alloy with 30mass% Si content and CrSi2 alloy with 10mass% Ni content were the most effective materials for application in the gas phase of air-(Na2SO4+25.7mass%NaCl) due to the formation of protective Al2O3/SiO2 and SiO2 scale, respectively. Therefore, it is realized that CoNiCrAlY-30mass% Si and CrSi2-10mass% Si coating are very effective for improving of high temperature corrosion resistance of STBA21 steel.


2018 ◽  
Vol 27 (3) ◽  
pp. 500-511 ◽  
Author(s):  
Reza Jafari ◽  
Esmaeil Sadeghimeresht ◽  
Taghi Shahrabi Farahani ◽  
Matti Huhtakangas ◽  
Nicolaie Markocsan ◽  
...  

2018 ◽  
Vol 775 ◽  
pp. 441-447
Author(s):  
Dong Bok Lee ◽  
Min Jung Kim ◽  
Gyu Chul Cho ◽  
Soon Young Park ◽  
Poonam Yadav

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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