Coupling Effects of Texture Density and Counterpart Material Hardness on the Dry Sliding Friction of TC4 Titanium Alloy

Circular microtextures with area densities of 5%, 10%, 15%, and 20% were fabricated on TC4 titanium alloy surfaces and tested under dry sliding conditions against four counterpart balls of varying hardness (Brass, SUS304, AISI 52100, and K20). Through coefficient of friction (COF) analysis, wear surface characterization, finite element simulation, and theoretical modeling, the friction‐reduction mechanisms of textured surfaces in different material pairings were systematically investigated. The results reveal that the effectiveness of microtextures is significantly influenced by the hardness of the counterpart material. For low‐hardness counterparts (Brass, SUS304), textures primarily reduce friction by entrapping wear debris. For high‐hardness counterparts (AISI 52100, K20), the variation in real contact area becomes the dominant factor, with 15% texture density exhibiting the best friction‐reduction performance. This study uncovers a transition in the friction mechanism of textured surfaces from “debris‐entrapment‐dominated” to “contact‐area‐dominated” behavior, providing theoretical guidance for optimizing texture density in different material systems.