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Are there any coatings or materials that can be used to store or transport hydrogen or helium that are resistant to embrittlement?

2007-10-14 06:16:11 · 1 answers · asked by Me! 1 in Science & Mathematics Engineering

1 answers

The following is taken from Wikipedia:
http://en.wikipedia.org/wiki/Hydrogen_embrittlement

If the metal has not yet started to crack, the condition can be reversed by removing the hydrogen source and causing the hydrogen within the metal to diffuse out - possibly at elevated temperatures. Susceptible alloys, after chemical or electrochemical treatments where hydrogen is produced, are often subjected to heat treatment in order to remove absorbed hydrogen.

In the case of welding, often pre- and post-heating the metal is applied to allow the hydrogen to diffuse out before it can cause any damage. This is specifically done with high-strength steels and low alloy steels such as the chrome/molybdenum/vanadium alloys. Due to the time needed to re-combine hydrogen atoms to the harmful hydrogen molecules, hydrogen cracking due to welding can occur over 24 hours after the welding operation is completed.

Hydrogen attack
If steel is exposed to hydrogen at high temperatures, hydrogen will diffuse into the alloy and combine with carbon to form tiny pockets of methane at internal surfaces like grain boundaries and voids. This methane does not diffuse out of the metal, and collects in the voids at high pressure and initiates cracks in the steel. This process is known as hydrogen attack and leads to decarburization of the steel and loss of strength.

Test
There is an ASTM standard for testing on hydrogen embrittlement[1]- F1459-06 Standard Test Method for Determination of the Susceptibility of Metallic Materials to Hydrogen Gas Embrittlement (HGE).

2007-10-14 06:32:33 · answer #1 · answered by gatorbait 7 · 0 0

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