Ultrasonic evluation of ceramic rolling elements

摘要

Using Si sub 3 N sub 4 as rolling elements in the P&W Space Shuttle Main Engine High Pressure Liquid Hydrogen Turbopump poses significant Non-Destructive Evaluation challenges. These challenges arise from the small critical flaw size that must be identified in the bearing rollers. A previously developed inspection for ceramic balls has shown an ultrasonic inspection can find flaw sizes on the order of 100 mum. A 100 mum size flaw was analytically determined as large enough to reduce ceramic bearing ball life in the form of spalling. These efforts are documented on ceramic bearing balls. The lessons learned from testing bearing balls were applied to the equally complex case of bearing rollers. The results of transitioning the inspection to the bearing roller effort will be discussed. Verification of the testing results will be presented.