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The effect of ion-plated silver and sliding friction on tensile stress-induced cracking in aluminum oxideA Hertzian analysis of the effect of sliding friction on contact stresses in alumina is used to predict the critical load for crack generation. The results for uncoated alumina and alumina coated with ion plated silver are compared. Friction coefficient inputs to the analysis are determined experimentally with a scratch test instrument employing an 0.2 mm radius diamond stylus. A series of scratches were made at constant load increments on coated and uncoated flat alumina surfaces. Critical loads for cracking are detected by microscopic examination of cross sections of scratches made at various loads and friction coefficients. Acoustic emission (AE) and friction trends were also evaluated as experimental techniques for determining critical loads for cracking. Analytical predictions correlate well with micrographic evidence and with the lowest load at which AE is detected in multiple scratch tests. Friction/load trends are not good indicators of early crack formation. Lubrication with silver films reduced friction and thereby increased the critical load for crack initiation in agreement with analytical predictions.
Document ID
19930043920
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sliney, Harold E.
(NASA Lewis Research Center Cleveland, OH, United States)
Spalvins, Talivaldis
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 16, 2013
Publication Date
February 1, 1993
Publication Information
Publication: Lubrication Engineering
Volume: 49
Issue: 2
ISSN: 0024-7154
Subject Category
Nonmetallic Materials
Accession Number
93A27917
Funding Number(s)
PROJECT: RTOP 505-63-5A
Distribution Limits
Public
Copyright
Other

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