Moisture and stress effects on fretting between steel and polyimide coatings

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dc.contributor.authorKang, Chiun-Chiaen
dc.contributor.committeechairEiss, Norman S. Jr.en
dc.contributor.committeememberFurey, Michael J.en
dc.contributor.committeememberWard, Thomas C.en
dc.contributor.committeememberWightman, James P.en
dc.contributor.committeememberWilkes, Garth L.en
dc.contributor.departmentMaterials Engineering Scienceen
dc.date.accessioned2014-03-14T21:14:36Zen
dc.date.adate2008-06-06en
dc.date.available2014-03-14T21:14:36Zen
dc.date.issued1993-07-15en
dc.date.rdate2008-06-06en
dc.date.sdate2008-06-06en
dc.description.abstractFretting of solvent cast polyimide coatings was investigated in a ball-on-flat geometry as a function of relative humidity. Polyimides were synthesized from benzophenone tetracarboxylic dianhydride (BTDA) and bisanline (Bis P), 6-fluoro bis dian hydride (6FDA) and Bis P, and pyromellitic dianhydride (PMDA) and bis A phenyl phosphine oxide (BAPPO). Coating life - the time for the steel ball to wear through the coating - shortened with increasing humidity. Iron oxides or other reaction products from 52100 ball generated at high humidity acted as abrasives and accelerated the wear of the coatings. Variation of coating life among the three polyimides was attributed to the residual stress, which developed upon cooling from the annealing temperature due to the mismatch of thermal expansion coefficients between the polymer and the metal substrate. Calculated from elasticity theory, the normal stress dropped shortly after the start of the test, remained relatively constant, and increased toward the end. This variation correlated with the wear rate and accounted for the non-linear increase of coating life with coating thickness. Sub-surface shear stress and surface tensile stress predicted well, respectively, the debonded shape and the inter-crack spacing of Hertzian cracks.en
dc.description.degreePh. D.en
dc.format.extentxiii, 166 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-06062008-171727en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06062008-171727/en
dc.identifier.urihttp://hdl.handle.net/10919/38491en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1993.K363.pdfen
dc.relation.isformatofOCLC# 29021797en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V856 1993.K363en
dc.subject.lcshCoatingsen
dc.subject.lcshFretting corrosionen
dc.subject.lcshPolyimidesen
dc.titleMoisture and stress effects on fretting between steel and polyimide coatingsen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineMaterials Engineering Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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