טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAlexander Yakhnis
SubjectMechano-Chenical Modification of Friction Surfaces Using
Microshot Peening
DepartmentDepartment of Design and Manufacturing Management
Supervisors Dr. Kligerman Yuri
Assistant Professor Varenberg Michael
Full Thesis textFull thesis text - English Version


Abstract

One of the two major approaches to bridging the gap between consumption and production of energy is to seek solutions for more efficient energy use. The reduction in energy consumption through reduced friction is the most straightforward one as about one-third of the world energy resources is expended on frictional losses. Frictional performance is governed by the topmost surface layer restricted to a few hundred nanometers underneath the contact interface. Thus, modifying physico-chemical properties of these layers is an obvious choice in trying to reduce friction and, hence, energy losses. This can be achieved by forming surface films containing sulfides, chlorides or phosphides, which are known for their ability to facilitate lubrication.

Extensive plastic deformation of a near-surface region achieved through finishing mechanical processes is known to be activating the surface due to heating and generating numerous defects that provide channels for easy diffusion of foreign atoms into the metal. Based on this, we have started developing a state-of-the-art technology allowing to synthesize low-shear-strength surface films by supplying sulfur-containing compounds during the microshot peening process.

To study the feasibility of this technology, cast iron surfaces were treated, analyzed to characterize their subsurface microstructure and chemical composition using a scanning electron microscopy, and tested to evaluate their lubricated friction performance using a ring-on-block test rig. The obtained results have demonstrated that the modified surface shows tens of percent lower friction even though the process parameters are yet to be optimized. This assures us that the idea is concrete and functional, and allows to anticipate a great future for this promising technology.