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  • Posted by $ jbrenner 7 years, 6 months ago
    From https://www.google.com/patents/US2013..., "nanolamination processes enhance the overall material properties of the bulk material by providing alternating layers of differing compositions on a nano-scale that significantly increases the material properties. The material can be strengthened by controlling grain size within each laminate and by also pinning nano-layers between interfaces of dissimilar compositions. Cracks or faults that arise are forced to propagate across hundreds or thousands of interfaces, which hardens and toughens the material by hindering dislocation motion." The last sentence is the key.

    From http://www.freepatentsonline.com/y201...
    "In embodiments where the electroplated compositions are comprised of a plurality of layers less than about 20 nm, the compositions display increased “Hall-Petch” hardness/toughness and strength. The observed increases in hardness results from grain confinement and increased toughness results from force reflection in the laminate regions. Such coatings tend to follow the Hall-Petch relationship, which traditionally is used to describe the increase in yield strength observed in nanocrystalline materials."

    The Hall-Petch relationship says that the log of hardness or yield strength vs. log of crystal diameter has a slope of -0.5, meaning that a crystal that is 1/4th in diameter is twice as hard. Traditionally, this has come at the expense of ductility and corrosion resistance, but Modumetal overcomes this with multiple nanolayers of electrolessly plated metals. The materials science of what Modumetal is claiming is reasonable. The main drawback to Modumetal's use of electroless plating is that it is typically slower than desired for mass production. I have done electroless plating of Ni and Pt before in the lab, but I am curious about production rates for Modumetal.
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