Nanoindentation of carbon microspheres

The indentation behavior of carbon microspheres was examined. The indentation load was in the range of 50 μN to 500 μN for the carbon microspheres with a diameter of ∼5 μm, and 15 μN to 100 μN for the carbon microspheres with a diameter of 1 μm. For the same ratio of the maximum indentation depth to the diameter of the carbon microspheres, both the contact modulus and indentation hardness for the carbon microspheres with a diameter of ∼5 μm are larger than the corresponding values for the carbon microspheres with a diameter of ∼1 μm. The carbon microspheres of ∼5 μm in diameter exhibited a larger resistance to the mechanical deformation than the carbon microspheres of ∼1 μm in diameter. The plastic energy dissipated in the nanoindentation increases with the increase of the indentation depth (load) and is a power function of the indentation depth.