Ph.D Thesis

Ph.D StudentVarenberg Michael
SubjectTribological Aspects of Nanoscale Fretting
DepartmentDepartment of Mechanical Engineering
Supervisors PROFESSOR EMERITUS Izhak Etsion
DR. Gregory Halperin


Tribological aspects of nanoscale fretting were studied by using quantitative scanning probe microscopy (SPM) and a new unified approach of slip index. The dimensionless slip index provides a unified approach to fretting that is valid for any particular system at any scale. It was verified under completely different conditions ranging from micro- to nanoscale and the fretting data was identical for all cases enabling to approximate it by a simple empirical law. A more accurate definition of fretting is offered based on this approach. The existence of nanoscale fretting wear is proven and nanoscale friction and wear results are demonstrated showing a significant difference between the different fretting regimes. It was found that kinematics of nanoscale fretting is similar to that of conventional microscale fretting, while the friction coefficient behavior differs significantly on different scales. The fretting wear behavior also seems to be similar on different scales.

The quantitative measurement of contact response with an SPM is not an elementary task and several related issues are also presented. These include: colloidal probe production by gluing microspheres to the ends of SPM cantilevers with an inverted light microscope and a three-axes manual micromanipulator; correction for cross-talk problems in scanning-by-probe SPM with a compensating electronic circuit; determination of bending stiffness of an SPM probe by using a commercially available SPM probe with a known stiffness; an improved wedge calibration method for lateral force that enables calibration of both integrated and colloidal probes for any single specified applied load, and utilizes a simple, commercially available calibration grating.