TechCorro Volatile Corrosion Inhibitors (VCIs) from ARMOR can reduce a metal's susceptibility to hydrogen embrittlement. TechCorro VCI molecules attach themselves to metal surfaces forming an invisible thin film. The VCI film will passivate the substrate, inhibit oxidation, and provide a barrier on the metal surface. This leads to a reduced susceptibility to hydrogen embrittlement.
What is Hydrogen embrittlement?
Hydrogen embrittlement is the process where metals become brittle following exposure to hydrogen. Hydrogen is first adsorbed onto the metal surface before penetrating the metal lattice in ionic form as protons. Hydrogen protons re-combine in lattice dislocations (micro voids) forming hydrogen molecules. The hydrogen molecules are unable to diffuse out of the metal matrix and will build pressure inside the micro voids. This hydrogen pressure will cause a marked loss in the plastic strain capacity of the metal, reducing the ductility and tensile strength.
Hydrogen embrittlement can occur during manufacturing processes, storage, or operational use - anywhere that the metal comes into contact with atomic or molecular hydrogen. Common ways in which hydrogen is introduced to the metal matrix include corrosion, chemical reactions on the metal surface and contact with acids or with other chemicals such as hydrogen sulphide or even water.
How do Volatile Corrosion Inhibitors work?
TechCorro VCIs are engineered highly specialised corrosion inhibitors based on aliphatic and nitrogen containing salts. The salts disassociate to form ions, permeating the packaging environment with corrosion inhibitors. The inhibiting ions are attracted to, and deposit on, metallic surfaces displacing moisture in the process and re-associating to form a stable nano-coating only a few molecules thick.
Components in TechCorro VCIs reduce the activity of hydrogen in the environment and on the metal substrate. Nitrogen-containing organic and inorganic compounds inhibit hydrogen from forming ionic protons. VCI molecules passivate the metal surface neutralising the effects of chemical contaminants. TechCorroâ¢ VCI nano-coating also forms an effective barrier to help prevent hydrogen-donating chemicals from coming in contact with the metal substrate.
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Kobrin, G. Metals Handbook, Vol. 13, Corrosion, 9th Edition. Metals Park, OH. ASM International, p. 321, 1986.