dc.contributor.author Troughton, SC en dc.contributor.author Nominé, A en dc.contributor.author Dean, James en dc.contributor.author Clyne, Bill en dc.date.accessioned 2016-09-07T09:51:22Z dc.date.available 2016-09-07T09:51:22Z dc.date.issued 2016-07-19 en dc.identifier.issn 0169-4332 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/259990 dc.description.abstract Short duration (~1 s) PEO treatments have been applied to aluminium alloy samples on which coatings of thickness ~100 $\mu$m had previously been created. This was done using the small area electrical monitoring system previously developed in the Gordon Laboratory in Cambridge. Voltage supply frequencies of 50 Hz and 2.5 kHz were employed. Fairly high resolution SEM micrographs were taken, covering the whole surface of small area samples (ie over a circular area of diameter about 0.9 mm). This was done both before and after the 1 s PEO treatments. X-ray tomographic data were also obtained in the vicinity of a recently-completed set of discharges. The outcomes of these observations were correlated with synchronised high speed electrical monitoring and video photography, carried out during the PEO treatment periods. Localised cascades (comprising hundreds of individual discharges) were observed in all cases, persisting throughout the 1 s periods and also reappearing in the same location when a second 1 s PEO treatment was applied to the same sample. This repetition of discharges at the same location is apparently due to the deep pores associated with these sites, creating a pathway of low electrical resistance, even after appreciable oxidation has occurred in the vicinity. Observations were made of the way in which the surfaces were reconstructed locally as discharge cascades occurred. With the high frequency voltage supply, discharge lifetimes were limited to the half-cycle period (of 200 $\mu$s), but in other respects the cascades were similar to those with the lower frequency. However, some discharges occurred during cathodic half-cycles with the high frequency supply, at the same location as the anodic discharges in the cascade concerned. dc.description.sponsorship Engineering and Physical Sciences Research Council (Grant ID: EP/I001174/1), Sims Scholarship, Keronite plc, Fundacion Banco Santander (Research Mobility Scholarship) dc.language English en dc.language.iso en en dc.publisher Elsevier dc.rights Attribution 4.0 International * dc.rights Attribution 4.0 International en dc.rights Attribution 4.0 International en dc.rights.uri http://creativecommons.org/licenses/by/4.0/ * dc.rights.uri http://creativecommons.org/licenses/by/4.0/ en dc.rights.uri http://creativecommons.org/licenses/by/4.0/ en dc.subject plasma electrolytic oxidation en dc.subject electrical discharge en dc.subject high speed photography en dc.subject X-ray tomography en dc.subject microstructure en dc.title Effect of individual discharge cascades on the microstructure of plasma electrolytic oxidation coatings en dc.type Article dc.description.version This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.apsusc.2016.07.106 en prism.endingPage 269 prism.publicationDate 2016 en prism.publicationName Applied Surface Science en prism.startingPage 260 prism.volume 389 en dc.identifier.doi 10.17863/CAM.4216 dcterms.dateAccepted 2016-07-16 en rioxxterms.versionofrecord 10.1016/j.apsusc.2016.07.106 en rioxxterms.version VoR en rioxxterms.licenseref.uri http://creativecommons.org/licenses/by/4.0/ en rioxxterms.licenseref.startdate 2016-07-19 en dc.contributor.orcid Clyne, Bill [0000-0003-2163-1840] dc.identifier.eissn 1873-5584 rioxxterms.type Journal Article/Review en pubs.funder-project-id EPSRC (EP/I001174/1) cam.orpheus.success Thu Jan 30 12:57:27 GMT 2020 - The item has an open VoR version. * rioxxterms.freetoread.startdate 2100-01-01
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