Exoelectron Emission for the Study of Surface Fatigue Wear

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Abstract
An apparatus has been constructed for studying exoelectron emission from steel bearing balls which have been run in a Barwell four-ball surface fatigue wear tester. The test ball is periodically removed from the tester, cleaned to remove its oil film, transferred to a vacuum chamber, and illuminated by ultraviolet light. The emitted exoelectrons originating at new surface area generated on the ball during fatigue testing are detected by an electron multiplier. By rotating the ball and measuring the exoelectron emission as a function of position, the source or sources of the emission can be localized. The resolution of the research apparatus is presently limited to 0.27 mm, the width of the scanning spot. Exoelectron emission decay results indicate a relatively slow drop in emission with time. Preliminary results indicate that the fatigue failure occurs at one of several sites which have given enhanced electron emission.