Spheroidal particles produced by cavitation erosion

Abstract

SMOOTH spherical particles have been observed during the microscopic analysis of wear surfaces (ref. 1 and R. S. Miller, personal communication) and of wear particles² using a new technique called ferrogram developed by Westcott². These investigators speculated that the spherical particles were produced by cavitation bubbles occurring at the contact surfaces of the bearing. The possibility of cavitation in bearings is well known³; however, it was difficult to understand how these bubbles could produce such perfect microspheres (in the range of 1 to 10 µm in diameter). To verify that cavitation erosion could indeed produce such spheres, we conducted careful experiments with the help of the American Society for Testing and Materials (ASTM) standard vibratory cavitation erosion apparatus; this communication reports the results of this investigation.