Measurement of mar resistance and study of marring mechanism of polymeric coatings with scanning probe microscope

A scanning probe microscope (SPM)equipped with a custom-made probe, consist ing of a diamond tip and rectangular tungsten cantilever, was used to measu re the mar resistance of crosslinked polymeric surface coatings at micron a nd submicron scales. The term "mar" is used to describe the surface damage of coatings, which may not be readily noticeable individually, however, the existence of many mars does degrade the appearance of coatings. Good mar r esistance is a requirement for many coatings applications. With the unique high resolution of the SPM, the dimension of the mars can be measured with great accuracy, thus different responses of coatings to the marring stress, i.e., elastic recovery, plastic deformation, and abrasive wear, can be ide ntified quantitatively. In addition, the dynamic process of marring, includ ing viscoelastic creep, strain-hardening micro-cracking, and surface fatigu e, has also been studied with the SPM.