I. Alfonso^1,2, J. Molinonuevo³, L. Mendizabal⁴, B. Coto³, N. Sala⁴, C. Colominas⁴, I. Quintanta³, A. Lopez⁵, J. A. García^1,2, I. Zalakain^1,2, A. Claver^1,2
1Universidad Pública de Navarra (UPNA), Pamplona, Spain
²Instituto de Investigación en Materiales Avanzados (INAMAT), Pamplona, Spain
³TEKNIKER, Eibar, Spain
⁴FLUBETECH, Castellar del Vallès, Spain
⁵INECFI, Lliçà de vall, Spain
Tool degradation remains a major challenge in precision metal forming, where punches and dies are exposed to high pressures and temperatures leading to accelerated surface wear. A common strategy to mitigate this is the application of hard ceramic coatings, such as CrN, TiN, AlCrN, or DLC, deposited by Physical Vapor Deposition (PVD). Additionally, Laser Surface Texturing (LST) has emerged as a promising technique to improve tribological behavior by creating micro-features like dimples, which can trap debris and act as lubricant reservoirs. The combination of both techniques has shown promising benefits, although further optimization is still required.
In this work, dimple-shaped textures were produced on AISI M2 steel prior to coating with AlCrN, aiming to reduce wear under boundary lubrication conditions. Three dimple density patterns (10%, 15%, and 20%) were fabricated using a femtosecond laser, with constant dimple diameter (Ø = 50 µm) and depth (~14 µm). Subsequently, an AlCrN coating (~1.8 µm thick) was deposited by HIPIMS, consisting of a 1.5 µm AlCrN layer and a 0.3 µm Cr interlayer. Surface characterization was performed by GDOES, SEM, and nanoindentation, along with wettability and oleic affinity measurements.
Tribological tests were carried out using a ball-on-disk configuration to study the influence of normal load (10–50 N) and sliding speed (0.08–0.21 m/s) on the coefficient of friction (COF). The effect of dimple density (10%, 15%, and 20%) on both COF and wear was also investigated under boundary lubricated conditions. Additionally, long-duration tests (750 m) were conducted to assess the wear behavior and calculate the wear coefficients for each textured surface. This enabled a comparative analysis of the different texture-load-speed combinations.