Corrosion of Corrosion-Resistant and High-Temperature Nickel-Based Alloys in Chloroaluminate Melts

Abstract

The corrosion resistance of Haynes 230, Hastelloy S and X hightemperature alloys and Hastelloy N, B-3, G-35, C-2000 corrosionresistant alloys was investigated in a wide temperature range (450-650 °C) in fused KCl-AlCl 3 mixtures. It was found that the mechanisms of corrosion of high-temperature alloys and corrosionresistant alloys in KCl-AlCl 3 based melts are different. At a critical temperature phase structure of the high-temperature alloys changes after contact with chloroaluminate melts resulting in formation of intermetallic or carbon-containing phases along the grain boundaries that result in increasing strength of the alloys but initiate intense intergranular corrosion. The structural changes in most of the corrosion-resistant alloys take place at higher temperatures but they also can cause structural changes in the materials. It was shown that both types of alloys undergo intergranular corrosion up to the critical conditions. Formation of different secondary phases was detected and their influence on the corrosion processes mechanism is analyzed.

Corrosion of Nickel-Based Superalloys in Molten Chloroaluminates

“…The initial mole ratio of AlCl3-to-KCl was equal to 1.1 in order to ECS Transactions, 77 (11) 753-766 (2017) create the worst possible conditions for the corrosion tests. Previously we demonstrated that corrosion rates were higher in acidic melts (9) due to increasing red-ox potential of the molten media in such conditions (10).…”

“…Previously (9) we reported the results of preliminary investigation of several hightemperature and corrosion-resistant alloys behavior in fused KCl-AlCl3 mixtures. It was found that the mechanisms of corrosion of high-temperature alloys and corrosionresistant alloys in KCl-AlCl3 based melts were different.…”

Corrosive Resistance of Nickel Hastelloy G-35 Superalloy in Various Aggressive Media

“…The rate of corrosion of the alloy samples in AlCl3-KCl melt was high because of the increased oxidizing ability of aluminum ions in the salt mixture (15,16). In the air atmosphere, the rate of corrosion was determined by the presence of oxygen, which diffused through the melt to the alloy samples and caused their high-temperature oxidation.…”

Corrosion of Metallic Materials in 3LiCl-2KCl and 3LiCl-2KCl-UCl3

“…Recently our group investigated corrosion resistant (Hastelloy® N, B-3®, G-35®, C-2000®) and high temperature (Haynes® 230®, Hastelloy® S and X) alloys in KCl-AlCl 3 melts (6). It was found that the mechanisms of corrosion of high-temperature alloys and corrosion-resistant alloys in KCl-AlCl 3 based melts were different.…”