Tribological properties of iron powder subjected to various surface treatments

The role of organic additives in dry pressing of metallic powders can be studied with the atomic force microscope (AFM) in terms of interaction forces,friction forces and shearing behavior. Material dependent properties in contact can be determined with the appropriate calibration of instrument sensitivities and spring constants. Force-distance curves give information about particle-particle interactions; measurement of static and dynamic friction provide additional information directly related to surface deformation. We present a fast and simple method for calibration of lateral cantilever deflection, independent of experimental setup. Experimental results on iron surfaces in contact show how adsorption of 12-hydroxy stearic acid yields different contact behaviour than commercial lubricants. This information also explains the hysteresis in friction-load experiments which can not be obtained from normal force curves or standard friction measurements alone.