Effect on microstructure of TiO2 rate in Al2O3-TiO2 composite coating produced using plasma spray method

摘要

Inthisstudy,Al2O3-TiO2compositecoatingswerethermallysprayedontheSAE1040steelusingatmosphericplasmaspray(APS)processofmixeddifferentratesmicron-sizedTiO2andmicron-sizedAl2O3powders.TheeffectsofTiO2additiononthemicrostructure,phasecompositionsandmicrohardnessofthecoatingswereinvestigatedbyusingscanningelectronmicroscopy(SEM),energydispersivespectroscopy(EDS),X-raydiffractometry(XRD)andmicrohardnesstester.TheresultsshowthattheAl2O3-TiO2compositecoatingsconsistsofbothfullymeltedregionsandpartiallymeltedregions,andthefullymeltedregionhasalamellar-likestructure.Phasetransformationsfrommainlystablealpha;-Al2O3andanatase-TiO2inthepowderstopredominantmetastablegamma;-Al2O3,rutile-TiO2andAl2TiO5phaseintheAl2O3-TiO2compositecoatingswereobserved.ItwasdeterminedthattheporecontentdecreasedwiththeincreasedintheTiO2powderrate.Themicrohardnessofthecoatinglayerswas3-4.5timeshigherthansubstratematerial.Theaveragemicrohardnessvaluesofthecoatingswerefoundtoreach650-860HV.