Qualitative Analysis of Surface Energy Using Atomic Force Microscopy Approach

This paper performs a qualitative analysis of the surface energy of copper (Cu), aluminum (Al), carbon steel (S45C) and alloy steel (SKD11) by analyzing the variation in the resonant frequency of the cantilever beam (Si
₃
N
₄
) of an atomic force microscope following repeated contacts with the specimen surface. In a pure material (Cu, Al and S45C), it is found that the adhesive mass on the tip of the cantilever beam saturates following repeated contacts with the surface. Since the adhesive mass is determined by the difference between the surface energy of the cantilever beam material and that of the test material, the surface energies of the cantilever beam and the pure materials can be qualitatively compared. However, for the alloy steel (SKD11), the adhesive mass varies after each contact and hence no conclusions can be made regarding its surface energy. The present results indicate that the surface energies of the cantilever beam and the pure materials can be ranked as follows: Cu>Si
₃
N
₄
>Al>S45C. It has been shown that the surface energy of a rigid material (S45C) is less than that of a soft material (Cu).