1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The stabbing resistance of graphene:

  1. May 22, 2013 #1
    I've read that it's several times stronger than steel. I haven't read anything about its stabbing resistance against the tip of a knife, though. Does anyone have any ideas on this subject? Could a human stab through an inch of it?
  2. jcsd
  3. May 22, 2013 #2


    User Avatar
    Gold Member

    Something like that will depend more upon the weave than the material. Stainless steel can let a bullet through, and wool can stop one.
    (By the bye, a Kevlar bullet-proof vest won't stop a knife.)
  4. May 22, 2013 #3
    Thanks for answering.

    I presume you're saying an inch of graphene itself would be impervious to a knife attack. However, if weaved incorrect, the tip of a knife can part the material; therefore, passing through the gap in the fabric?
  5. May 22, 2013 #4


    User Avatar
    Gold Member

    I don't actually know anything about graphene, but you have my concept understood. Kevlar acts almost like a sheer-thickening fluid when a bullet hits it; ie: it spreads the impact over a very wide area. A knife, on the other hand, can just slip through between the fibres. Many people have been dismayed to learn that during combat.
  6. May 22, 2013 #5
    From what I can remember, Kevlar is stronger than steel. How is it that scissors can cut through a Kevlar string? In this case, wouldn't the fibers actually be getting cut instead of parted?
  7. May 22, 2013 #6


    User Avatar

    Staff: Mentor

    Scissors can cut through steel wool (i.e., steel fibre).
  8. May 22, 2013 #7
    Well an "inch thick" sheet of graphene would essentially just be a slab of graphite. You could do this test yourself pretty easily.
  9. May 22, 2013 #8
    Well, I did do some more research today and found something interesting: “It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap.”

    I presume that basically would be equal to stabbing graphene.
  10. May 24, 2013 #9


    User Avatar
    Gold Member

    I'd really like to see a reliable source for that quote, because it reeks of BS.
  11. May 29, 2013 #10
    Link to Columbia professor James Hone saying this.

    That said, there are a number of reasons why this quote is misleading.
    1: Stacking layers of graphene leads to the formation of graphite. Unless you can find a way to stack graphene without having individual sheets bond to each other, the quote will never be tested.
    2. This makes people think an individual sheet of graphene is incredibly strong on the macroscale, it's not. I can easily cut through a graphene sheet with a pair of scissors.

    Now if we can make a sandwich of graphene along with another 2D material (Hexagonal Boron nitride, for example) there is a possibility of being able to test a modified version of the saran wrap theory.
  12. May 29, 2013 #11


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    Could be BS or it could just refer to the 'spreadability' of graphene. What sort of backing material would need to be used in order, actually, to support this elephant. I imagine that the layer of graphene could be very thin so, by some measure, you could say it hadn't been 'punctured'. A similar statement could possibly be made about a number of high pressure lubricating oils.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook