NanoTribology

Mechanical properties such as hardness, elastic modulus, stiffness and compressibility as well as material behavior such as plastic deformation, and fracture can be studied with the AFM.

It is possible to study nano-hardness by directly pressing an AFM probe into a sample's surface; however, it is advantageous to use an instrument that is optimized for nano-indentation. The primary advantage of the nano-indenter over an AFM for nano-hardness measurements is that it is easier to get calibrated measurements with the nano-indenter. It is useful to use the AFM to measure the three-dimensional topography of indentations made with a nano-indenter. AFM images allow direct visualization of material deformation or fracture behavior.

Using techniques such as pulsed force mode, the stiffness of a sample at a matrix of locations is measurable. From this data it is possible to create a stiffness mapping of a surface. Stiffness maps can only be made on samples where the stiffness of the surface is lower than the stiffness of the cantilever. Such stiffness images are routinely measured on polymer samples.

Adding a fixture to the stage of the AFM makes the study of material behavior such as plastic deformation and fracture possible. The fixture permits creating forces on a sample while AFM images are being taken. A variety of materials may be studied with such a technique.