Measurement of Friction Surface and Wear Rate between a Carbon Graphite Brush and a Copper Ring

Abstract

A pin-on-disc surface friction tester designed by the authors was used to measure the surface friction temperature of a carbon graphite brush sliding against a copper ring under the condition of no flow by electric current. Microelectromechanical systems (MEMS) fabrication techniques including sputtering, lithography, and etching processes were utilized to fabricate metal film temperature sensors on the surface of the carbon graphite brush. The true temperature measurement system of the friction surface of the carbon graphite brush was then established. A USB-DAQ system and LabVIEW software were adopted for the data acquisition/management of analog signals. In this research, the relationship between friction temperature and wear rate was investigated using experiment data. Optical and scanning electron microscope (SEM) images of the friction surface of the carbon graphite brush were taken and analyzed to study the effect of temperature on the friction surface. From this experiment, it was found that the debris of a mixture of brush and copper particles softens under high temperature, adheres to the brush surface, and forms flattened areas. These smooth, flattened areas in turn lower the friction coefficient.

KEY WORDS:

• Friction
• Wear
• Measurement

ACKNOWLEDGEMENT

The authors are grateful to the MEMS & Precision Machinery Common Laboratory, Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, for providing free access to the MEMS devices fabrication equipment.

Review led by Jane Wang