A team at the University of Hong Kong has developed a new “super steel” that can survive the harsh conditions needed to make green hydrogen from seawater. The material uses an unexpected double-protection mechanism that resists corrosion far better than conventional stainless steel. Even more impressive, it could replace costly titanium parts used in today’s hydrogen systems.
  • Teal@lemmy.zipEnglish
    19·
    2 days ago

    The first layer is the familiar Cr2O3 based passive film. Then, at around ~720 mV, a manganese based layer forms on top of the chromium based layer. This second shield helps protect the steel in chloride containing environments up to an ultra high potential of 1700 mV.

    That is what makes the finding so striking. Manganese is usually not viewed as a friend of stainless steel corrosion resistance. In fact, the prevailing view has been that manganese weakens it.

    “Initially, we did not believe it because the prevailing view is that Mn impairs the corrosion resistance of stainless steel. Mn-based passivation is a counter-intuitive discovery, which cannot be explained by current knowledge in corrosion science. However, when numerous atomic-level results were presented, we were convinced. Beyond being surprised, we cannot wait to exploit the mechanism,” said Dr. Kaiping Yu, the first author of the article, whose PhD is supervised by Professor Huang.

    They know how to make it work. The currently unexplainable part is why because manganese is the key to this working. Manganese usually doesn’t protect stainless steel from corrosion but it is when layered over the chromium based layer.