טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentKreines Leonid
SubjectFretting Wear of Thin Film Diamond Coatings
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Emeritus Izhak Etsion
Dr. Gregory Halperin


Abstract

The use of diamond coatings in industry is constantly increasing due mainly to its special characteristic properties. Diamond is a unique substance with exceptional optical, mechanical, thermal and electrical properties. Due to high density and strong atomic bonds of the carbon atoms in the structure the diamond also has high hardness and great resistance to mechanical wear. 

A large number of scientific publications appeared in recent years on diamond coating properties in general and on thin diamond coatings on steel substrate in particular.  The research on wear mechanisms of diamond coatings in friction process is of great interest to the scientific community. Various contradicting results are reported in the literature regarding the relation between the coatings thickness and their lifetime. This may be attributed to different wear mechanisms (e.g. abrasive or fatigue), which could have opposite effect on wear depending on the coating thickness.

The main goal of the present work is to study the friction wear mechanism of diamond coatings on steel substrate under fretting conditions at various diamond film thicknesses. In order to simulate fretting, an experimental rig, assembled according to the ball-on-flat contact scheme, was used.

The results showed that the dominant wear mechanism of the diamond coatings, when both surfaces are coated, is an abrasive form of fretting wear. Under these conditions the lifetime of the diamond films increased with increasing film thickness. It was found that the wear rate during the main period is independent on the initial thickness of the diamond film and therefore its life depends on the residual thickness at the end of the running in period.