Contents lists available at ScienceDirect Wear journal homepage: www.elsevier.com/locate/wear Synergistic effect on the tribological properties of tool steel through the use of laser surface texturing channels and nanoparticles Demófilo Maldonado-Cortés a, ⁎ , Laura Peña-Parás a , Vicente Barrios-Saldaña a , José Santiago Cruz-Bañuelos a , Marcin Adamiak b a Universidad de Monterrey, Av. Morones Prieto 4500 Pte., San Pedro Garza García, N. L. 66238, Mexico b Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Gliwice, Poland ARTICLE INFO Keywords: Tribology Surface texturing Channels Nanoparticles Deep drawing ABSTRACT Many studies have been focused on the positive effect of laser surface texturing (LST) for tribological perfor- mance of several metal mechanic tools and machine elements. Different geometries have been studied and benefits have been found in the two main tribo characteristics: coefficient of friction (COF) and wear. The most analyzed geometry, because of its ease of manufacturing, is the circle. Not enough has been studied respective of the effect of the orientation of micro channels and nanoparticles in lubricants together. This work shows the results obtained by adding the synergistic efforts of the use of laser surface texturing channels in two orientations (vertical (V) or horizontal (H)) and the use of TiO 2 nanoparticles dispersed at 0.05 wt% within a poly alpha olefin (PAO4). A T-05 conformal contact block-on-ring equipment was used for the tribological tests (COF and wear values) according to ASTM G77 standard with continuous revolutions ensuring constant lubrication. The output parameter of surface finish was measured using a 3D Alicona Edgemaster surface analyzer. Reductions of up to 76% and 89% were reached for COF and wear respectively for laser surface textured test blocks. The addition of nanoparticles was able to reduce also COF by 68% and 97% in wear; also improvements in roughness was founded when micro channels and nanoparticles (NP) was used together in values up to 50%. With this study the synergistic effect of channel texturing (including orientation of the channels) and the use of nano- particles on lubricants in conformal contact processes such as for deep drawing processes was demonstrated. 1. Introduction Deep drawing dies give shape to metal parts in different industries such as automotive, aeronautic, and white goods [1]. During this ex- treme pressure process, the die exhibits wear due to the friction, sliding movement between the die and the steel sheets, and the high load cases in the tribological systems. After a certain amount of cycles, the stresses generate cracks in the tools that lead to fracture, disabling the die for future use. These issues have increased because of the usage of higher strengths steels that need a greater forming load and the non-inter- ruptive functionality of machines, which diminish the life of tools [2,3]. In order to reduce the coefficient of friction (COF), different ap- proaches such as the use of lubricants, heat treatment, hard coatings, soft coatings, higher strength materials, or surface texturing have been used to improve this tribological parameter. In lubrication, a coating of a solid or liquid material is placed between the two elements that are at contact and with relative motion between each other. This element can have the addition of nanoparticles to further enhance the tribological characteristics [4–6]. Surface texturing is the process of removing material via high temperatures though a laser, by chemical reactions such as etching, or by a mechanic mean (grinding); with the most popular being the first due to the technological advances that have reduced the pulse width from nanosecond to femtosecond and by the amount of competition that has been added to the field, lowering cost significantly [7,8]. From all the methods described above, none has worked as well as micro cavities generated by laser surface texturing (LST) [9]. This re- source is best known for being used in the surface of modern magnetic storages to counteract the adhesion and device structure of MEMS and magnetic seals [9]. Micro cavities improve the load capacity by creating hydrodynamic pressure, helping against wear by becoming “traps” for the debris that is generated within the system through the deterioration that comes with the usage, and decrease the COF by becoming micro deposits of lubricant and preventing starvation [10]. As stated before, due to the reduction of cost and an increase in precision, LST is the most familiar way of creating micro cavities. The https://doi.org/10.1016/j.wear.2019.01.040 Received 1 September 2018; Received in revised form 3 January 2019; Accepted 8 January 2019 ⁎ Corresponding author. E-mail address: demofilo.maldonado@udem.edu (D. Maldonado-Cortés). Wear 426–427 (2019) 1354–1361 0043-1648/ © 2019 Elsevier B.V. All rights reserved. T