Mechanisms of Erosion.
Final rept. 1 Apr 77-31 May 80,
PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
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A single stage gas gun and a whirling arm rig have been used to study the erosion of mono- and poly-crystalline MgO and Al and mono-crystalline LiF targets by millimeter scale steel and WC - 6 Co spheres. Both single and multiple impact studies were variously performed as functions of impact angle, impact velocity, particle size, method of surface preparation and in the case of mono-crystalline targets surface orientation. The resultant damage was variously studied by optical and scanning electron microscopy, dislocation etching and surface profilometry, and the corresponding mass losses were determined gravimetrically. In addition, a computer model of oblique impact was developed and tested against the experimental observations. The results show that the variation of impact crater dimensions with impact conditions can generally be explained satisfactorily, but that it is difficult to relate mass loss to crater geometry in quantitative terms under either single or multi-particle impact conditions. They also suggest that the erosion of semi-brittle materials is determined primarily by the intersection of the lateral and median or radial cracks formed about the impact craters, and that ductile materials erode by the detachment of thin platelets formed by extrusion of piled-up material between subsequently arriving particles and the underlying substrate. Author
- Physical Chemistry