Presentation of the project
The role, sometimes beneficial, of rough surfaces in lubrication processes raised the interest of researchers at national and international level long time ago. Starting from this point, controlled micro-topographies were generated and were called under the generic name of textured surfaces (STX). These surfaces produce or amplify the hydrodynamic effects and reduce friction. By textured surface we understand a regular form of micro-topography of the surface realized by periodical creation of dimples or proeminences which are practically identical. The lubrication of textured surfaces became in the last years a subject with high dynamics in the field of research. Although the first researches began in 1960, the first systematical studies began to appear only after 1990, followed by the first industrial applications. In Romania, the Chair of Machine Elements and Tribology (OMT) from UPB, initiated theoretical and experimental researches in this direction since 2003, realizing, beside the theoretical studies of simplified modeling, the first experimental model using chemical erosion. An alternative in realizing textured surfaces, much more productive and which doesn’t necessitate special fabrication preparation is laser surface texturing. This technique was not used until present in Romania for the realization of STX. Recently (2005), one of the members of the team (Victor Marian from OMT) realized the laser texturing of an axial bearing, in the frame of a DAAD research scholarship undertaken in Germany, in consequence we dispose of a minimal experience in approaching this problem.
| Even if potentially STX has as research interest all the applications for which is necessary to realize self-sustained films for parallel surfaces, associated with drastic reduction of friction coefficient, until present the employed applications are concentrated on mechanical seals, axial bearings (especially those of hard-drives), or piston-liner couple. At the same time, surface texturing represents one of the possible solutions in bio-tribology (articular prosthesis). Possible applications in the field of radial bearings are not known, but principally, the advantages of texturing shown in the case of axial bearings can be found in journal bearings. |  |
The study of textured surface lubrication encloses four poles of interest: fabrication (technology), dimensional control, phenomenology (modeling) and application (utilization). The present project is aimed on the realization of the following key objectives:
- Realization of STX models by laser ablation, novelty at national level. The models will be realized on plane and cylindrical surfaces (on the inner side).
- Evaluation of the geometry and physico-chemical characteristics of textured surfaces.
- Tribological evaluation of STX by testing the experimental models on tribological test rigs (pin-on-disk) in case of wet and dry friction
- Testing of STX in real functioning conditions, on radial bearings
- Analytical and numerical modeling of the lubrication of textured surfaces realized by partial or total texturing in order to define a method of computation for these surfaces
The proposed subject, with a highly pronounced interdisciplinary character, is based on a collaboration between a partner wich owns the laser ablation technology (INCDFLPR), a partner which owns an equipment of metallographic and microgeometric evaluation (METAV) and a beneficiary of the technology applied to radial bearings (COMOTI), which will test and validate their utility. OMT from UPB, the coordinator of these activities will realize the design of the experimental models, their tribological testing on specialized test rigs and the realization and validation of the theoretical models.