The Wear of Polymers by Transferred Films.
Abstract
A wear measuring technique was developed using radioactive tracers. The technique was capable of detecting less than 1 microgram of polymer transferred to a steel surface. The technique was used to measure the wear of PCTFE and PVC in sliding experiments at sliding speeds of less than 1 cm/sec by detecting the CL38 isotope which had been made radioactive by neutron bombardment. Low density polyethylene was doped with one percent Dy2O3, and the wear measured by tracing the DY165 isotope. Scanning electron microscope observations of the the wear process showed that transfer of polymer occurred at the highest asperities on the steel surface. The transferred polymer had sheared off at an angle and the shear angles were significantly different for different polymers. The amount of polymer transfer for repeated passes over the same surface was shown to be a function of the angle that the sliding direction made with the lay on the surface. The amount of transfer was least when sliding parallel to the lay, intermediate when sliding perpendicular to the lay, and highest at angles between 10 and 80 degrees. The highest wear resulted from transferred polymer being continually moved to the edge of the wear track on subsequent passes. Wear models were proposed for full penetration of the steel surface into the polymer pin (apparent and real areas approximately equal) and partial penetration (apparent area larger than real area). While the model could predict the relative wear of PVC and PCTFE, it predicted that asperity slopes necessary to cause shear stresses high enough for polymer fracture were larger than those measured on the surfaces. The partial penetration model was based on penetration depth and shear angle.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 15, 1977
- Accession Number
- ADA037104
Entities
People
- Norman S. Eiss Jr
Organizations
- Virginia Tech