Abstract
This article features with the enhancement of the static coefficient of friction by laser texturing the contact surfaces of tribological systems tested under dry friction conditions. The high-rate laser technology was applied for surface texturing at unprecedented processing rates, namely using powerful ultrashort pulses lasers in combination with ultrafast polygon-mirror based scan systems. The laser textured surfaces were analyzed by ion beam slope cutting and Raman measurements, showing a crystallographic disordering of the produced microscopic surface features. The laser induced self-organizing periodic surface structures as well as deterministic surface textures were tested regarding their tribological behavior. The highest static coefficient of friction was found of µ20 = 0.68 for a laser textured cross pattern that is 126% higher than for a fine grinded reference contact system. The line pattern was textured on a shaft-hub connection where the static coefficient of friction increased up to 75% that demonstrates the high potential of the technology for real-world applications.
Highlights
Laser surface texturing has been established as an effective method to tailor and control the micro-topographic and physiochemical properties of surfaces
The static coefficient of friction (COF) were calculated onthe the basis of the maximum torque values determined for the torsion angles 0.01° and 0.1° that is equivalent to 2 μm and 20 μm lateral displacements in the frictional contact area
The maximum value of the COF μmax that could be obtained within the tested range (φ ≤ 3°, sF ≤ 600 μm) will be presented. It should be mentioned for the static COF Type A, most commonly the maximum value will be obtained within 20 μm lateral displacement, while for COF Types B and C, the basis of the maximum torque values determined for the torsion angles 0.01◦ and 0.1◦ that is equivalent to 2 μm and 20 μm lateral displacements in the frictional contact area
Summary
Laser surface texturing has been established as an effective method to tailor and control the micro-topographic and physiochemical properties of surfaces. The pulse distance pd was set of about the focus spot diameter and with little overlap in orthogonal direction (slow axis) as the line distance ld between the raster scanned lines was half of the spot diameter In initial studies, such kind of weak surface roughness is considered as inter-pulse feedback mechanism for the self-organizing formation of regular surface patterns as induced upon multi-pulse laser irradiations [30,31,32]. A further technical development is schematically illustrated, combining the polygon scanner and a four-spot diffractive optical element (DOE) for ultrafast and parallel surface texturing APReff for 1) 40% facet utilization rate, 2) 3 scan passes and 3) 40 mm field length
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
