Closed regions: a proposal for spacing parameters for areal surface measurements

Surface topography plays a significant role in functional performance situations like friction, lubrication and wear. Surfaces can be characterized by two-dimensional parameters but nowadays researchers are investigating areal parameters, which are better descriptors of the real nature of surfaces in contact. This paper proposes new spacing parameters, which describe closed peak contact regions and closed valleys lubricating regions. The parameters are shown to have the same order of statistical stability as the amplitude roughness parameters, and preliminary results on correlation with functional performance are illustrated.