简介:YAGlaserweldingwithsurfaceactivatingfluxhasbeeninvestigated,andtheinfluencingfactorsandmechanismarediscussed.TheresultsshowthatbothsurfaceactivatingfluxandsurfaceactiveelementShavefantasticeffectsontheYAGlaserweldshape,thatistoobviouslyincreasetheweldpenetrationandD/Wratioinvariousweldingconditions.Themechanismisthoughttobethechangeofweldpoolsurfacetensiontemperaturecoefficient,thus,thechangeoffluidflowpatterninweldpoolduetotheflux.
简介:Aneodymiumdopedyttriumaluminumgarnet(Nd:YAG)transparentceramicwasfabricatedbyasolidstatereactionmethodusingcommercialα-Al2O3,Y2O3,andNd2O3powdersasstartingmaterialsandtetraethylorthosilicate(TEOS)assinteringaid.ThemorphologyandmicrostructureofthenanopowdersandtheNd:YAGtransparentceramicwereinvestigated.ThefullydenseNd:YAGceramicwithanaveragegrainsizeof~20μmwasobtainedbyvacuumsinteringat1720°Cfor12h.Fewporesandgrain-boundaryphaseswereobserved.Thein-linetransmittanceoftheceramicwas81.5%at1064nm.
简介:TheenergymodelwasfoundedtocalculatethecriticalpowerofkeyholeformationbyusingthelimitprincipleinCW(continuouswave)Nd:YAGlaserdeeppenetrationweldingprocess.Themodelwasvalidatedbyexperiments.Theresultsshowthattherearetwoerrorsbetweenthecalculatedcriticalpowerofkeyholeformationandthatofexperiments:oneisthatthecalculatedresultsislessthanthoseofexperiments,whichiscausedbynotconsideringtheenergylossby!heatconductioninthemodelofkeyholeformation.Theotheristhatthereis0/9mmerrorbetweentheaxisofthecalculatedcurveofcriticalpowerwithlocationoflaserfocusandthatofexperimentalcurve,whichisinducedbytheexcursionoflaserfocusinlaserdeeppenetrationwelding.Atlast,thetwoerrorswererevisedaccordingtotheanalysesoftheerrors.
简介:AnexperimentalsetupofacquiringthecoaxialvisualimageofthemoltenpoolandkeyholeinhighpowerNd:YAGlaserweldingisintroducedinthispaper.Itisoneofthemostdifficultproblemsinacquiringcoaxialimagethatthecoaxialimagingsignalofmoltenpoolandkeyholemustbeseparatedfromthelaserbeamwithhighpower.Thisproblemwasresolvedbydesigningadichroiticspectroscope.Thecharacteristicsofimagingsignalwereanalyzedandthecoaxialimageofmoltenpoolandkeyholewasacquired.Asmoothingfilterandahomomorphicfilterweredesignedtoremovethelowfrequencynoiseandtoenhancetheimageaccordingtothecharacteristicsofimagingsignal.Atlast,edgesofmoltenpoolandkeyholeweredetectedandextractedbasedonimagesegmentationwiththreshold.