基于頻譜分析的材料表面改性層特性超聲無損表征.pdf

1、大連理工大學(xué)碩士學(xué)位論文基于頻譜分析的材料表面改性層特性超聲無損表征姓名：徐志輝申請學(xué)位級別：碩士專業(yè)：材料學(xué)指導(dǎo)教師：林莉李喜孟20050301莖王塑墮坌塑塑塑墊耋亙墮絲星壁絲塑生垂塑耋竺UltrasonicNondestructiveCharacterizationforPropertiesofModificationLayersofSurfaceMaterialsBasedonSpectralAnalysisAbstractMod

2、ificationlayersofmaterialssurfacewereappliedextensivelyinaerospace，petrifaction，micro—electronicsandautomobilemanufactureengineeringfieldsetc，ultrasonicnondestructivecharacterizationforitsproperties，suchasgeometryscale，e

3、lasticmodulus，bondingstrengthandresidualstressetc，wasverysignificantinqualityevaluationofmodificationlayersBecausemodificationlayersthicknesswassmallandincludedheterogeneousthinlayers，ultrasonicsignalsfromheterogeneityin

4、terfacesoverlappedandinterferedThus，ultrasoniccharacteristicparametersofmodificationlayerswerehardtobeacquiredInthepaperoneultrasonictestingandsignalprocessingsystemofpulse—echowithimmersedfocusinghasbeensetupforcharacte

5、rizationofmodificationlayersofmaterialssurface，byoptimizingultrasonictestingmethodanddesigningexperimentparametersbasedonultrasonicpropagationspecialityinmulti—layerThecrystaIdiameterofultrasonictransducerwas7mm，centerfr

6、equencywas10MHz，andthecurvatureradiusofacousticlenswas55mm，focusinwaterwas156mnl，displacementprecisionoftransducerwasOOlmmInadditioncomputerwasusedtoprocessultrasonicsignalsbyOriginsoftwareTheultrasonictestingsystemwasus

7、edtomeasurethethicknessofZr02ceramiccoatings(270—400lam)plasmasprayedonsuperalloyAccordingtospectralanalysisforthicknessmeasurementofmulti—layermaterials，thefrequencyinterval△廠ofperiodicminimainnormalizedpowerspectrawaso

8、btainedBasedontherelationshipr^=v／2AJ)betweenacousticvelocityvandfrequencyintervalAf，thethicknesshofZr02ceramiccoatingscanbecalculated，andthecoatingsthicknessof400Itm，339“m，277pinaccordedwiththoseofmetallographicmethodTh

9、isultrasonictestingsystemwasalsousedtotestCr20sceramiccoatingsonstainlesssteelirradiatedbyhighintensitypulsedionbeam(HIPIB)at300A／cm2withl一10shots，andthespectralanalysistechniquewasadoptedtoprocessultrasonicsignals。Withi