Investigation of mechanical properties of surface layer of polymeric elements of miniature slide bearing using atomic force microscope

摘要

Theoretical fundamentals of atomic force microscopy (AFM) have been presented in details.The course of force-distance curve being the base of measurements of modulus of elasticity of material surface layer,obtained using AFM method,has been analyzed (Figs.1 and 2).The own modification of AFM method (dynamic force spectroscopy variant) was characterized.It bases on putting the testing probe in resonant vibration and further vibrating probe approach to the investigated sample surface (Fig.3).Amplitude-distance curve (Fig.4) consists here the analyzed function.The method described has been used to investigate the dependence of modulus of elasticity (E) on the depth of probe indentation,for various polymeric materials (ABS terpolymer,polyamides,polycarbonate,polystyrene or polyacetal) (Fig.6).It was found that E reaches maximal value on a free surface (without a load,point indentation depth about 0 nm) independently on the type of polymer.Polycarbonate and polyacetal containing 20 wt.% of polytetrafluoro-ethylene showed the highest values of a modulus from all the polymers investigated.The results obtained show the necessity of taking E variability into account in calculations of friction or mechanically deformed mating surfaces.