Colorimetry and Tribology of Ultrapure Copper Surface Micromodification

ABSTRACT Controlling optical and tribological properties of metal surfaces, like color and wear rate, without altering their chemical composition is a highly desirable process. It represents a cost‐effective alternative to traditional chemical methods, particularly for copper, one of the most important metals widely used. We investigated the control of copper surface texture through a controlled micromodification process, utilizing constant force and velocity with abrasive silicon carbide sandpaper on ultrapure copper pellets exhibiting elongated crystallographic grains, and its impact on optical properties. Systematically varying grit size and rubbing direction, both along and across the grains, resulted in tunable microgroove morphology. Modification along copper grain boundaries yielded a change in the wear rate by a factor of two, related to single‐grain and multi‐grain abrasion regime changes, enabling precise control over material performance via tuned abrasion conditions. Colorimetric analysis via C‐Microscopy revealed a strong, statistically significant relationship between abrasive parameters, microgroove geometry, and optical spectral signatures, which were then parametrized to achieve targeted control. This research demonstrates a simple yet effective approach to color and reflectance modification via microgroove engineering, offering a pathway to customized material properties by uniquely coupling contact mechanics, surface morphology, and colorimetry at the microscale level.