Corrosion resistant material at high temperature/high pressure?

[Spindre]

Hi I am about to fabricate a part exposed to super critical water (600C & 250bar).

In the past people have been using titanium or convoluted methods to prevent excessive corrosion induced by dissolved solids (principally Cl-), which under supercritical conditions precipitate, coming back into solution in high pressure/high temperature but sub-supercritical water.
FYI, the water will also have a high to near-saturated dissolve oxygen level. Also some shockwaves will travel throughout the water when the arc ignites the introduced oxidizer to flash heat the water up to the required temperatures, ergo ceramics have also not performed well.

Now, even titanium or titanium coated steel didn't last particularly long in the days when people were working with supercritical oxidation. I would hope that by now a new material have been discovered, which can withstand these conditions for 5000hrs.

The material will be supported by the pressure vessel, so it only needs to be able to withstand temperatures up to 600-700C and the corrosion.

 

[Astronuc]

Hi I am about to fabricate a part exposed to super critical water (600C & 250bar).

In the past people have been using titanium or convoluted methods to prevent excessive corrosion induced by dissolved solids (principally Cl-), which under supercritical conditions precipitate, coming back into solution in high pressure/high temperature but sub-supercritical water.

FYI, the water will also have a high to near-saturated dissolve oxygen level. Also some shockwaves will travel throughout the water when the arc ignites the introduced oxidizer to flash heat the water up to the required temperatures, ergo ceramics have also not performed well.

Now, even titanium or titanium coated steel didn't last particularly long in the days when people were working with supercritical oxidation. I would hope that by now a new material have been discovered, which can withstand these conditions for 5000hrs.

The material will be supported by the pressure vessel, so it only needs to be able to withstand temperatures up to 600-700C and the corrosion.

What is the application? A lifetime of 5000 hrs is rather short? Certainly an oxidative environment with Cl^- is rather aggressive, especially as temperature increases. What kind of dissolved solids? Cl^- is an ion (anion), so it's in solution. The concern with Cl and halides, and polythionic acids, in general, is stress corrosion cracking. Halides and polythionic acids undermine the protective layers on alloys like stainless steel, and other systems.