简介：Inthisstudy,micro-hollowcathodedischarge(MHCD)isinvestigatedbyafluidmodelwithdrift-diffusionapproximation.TheMHCdeviceisacathode/dielectric/anodesandwichstructurewithoneholeofadiameterD=200μm.ThegasisaNe/Xemixtureatapressurep=50～500Torr.Theevolutionsofthedischargeshowthattherearetwodifferentdischargemodes.AtlargerpDthedischargeplasmaandhighdensityexcitedspeciesexpandalongthecathodesurfaceand,aringeddischargemodeisformed.AtsmallerpD,thedischargeplasmaandtheexcitedspeciesexpandalongtheaxisofthecathodeaperturetoformacolumnardischarge.

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简介：Electricalpropertyofamicro-plasmaspraysystemwithdifferentworking-gasfeedingschemeswastestedtooptimizetheplasmasprayprocess.Thearcvoltagewithanintegratedgasinjectionmodeishigherthanthatwithradialinjectionoraxialinjectionmodes.Thus,anintegratedgasinjectionmodewithanexcellentelectricalcharacteristicwasadoptedtodepositalumina-titaniacoating.Themicrostructure,bondingstrengthandhardnessoftheplasmasprayedalumina-titaniacoating,asafunctionofthesprayingparameters,e.g.,plasmacurrent,gasflowrateandgaspressure,werestudied.Itwasshownthatthesprayingparametersaffectedremarkablyontheinicrostructureofthecoating.Differenttendenciesinbondingstrengthandhardnesswerealsoshownfordifferentsprayingparameters.Atanarccurrentof250A,agasflowrateof20L/rninandagaspressureof0.5MPa,thebondingstrengthandmicro-hardnessofthecoatingsreach40.6MPaandHV1406.1,respectively.