简介：Sodiumparanitrophenolatedihydrate(NPNa·2H2O)isanexcellentsemiorganicnonlinearoptical(NLO)material,crystallizesbothinwaterandmethanolwithhighdegreeoftransparency.Goodopticalqualitysinglecrystalsofdimensionupto18mmx6mmx3mmareobtainedbyisothermalsolventevaporationtechnique.Thesolubilityofthecrystalindifferentsolventswasmeasuredgravimetrically.ThesinglecrystalsofNPNa·2H2Oshowvariationinphysicalpropertiesandgrowthrateindifferentsolvents.Methanolorethanolsolutionyieldscrystalsofbipyramidalshapewithclearmorphology.However,methanolgrowncrystalisexhibitingimprovedhardnessparametersandpossessesexcellentthermalstabilityascomparedtowatergrowncrystals.TheeffectsofsolventonhardnessparameteralongwiththermalandopticalpropertiesofNPNa·2H2Owasrevealedinthispaper.

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简介：Lowtemperaturecompositechromizingisaprocesscomposedofaplainion-carbonitridingorion-nitridingat550～580℃,followedbyalow-temperaturechromizinginasalt-bathof590℃.ThemicrostructureandpropertiesofthelowtemperaturecompositechromizedlayeronH13toolsteelwereinvestigatedusingmetallography,X-raydiffraction,microanalysis,hardnessandweartests.Itwasfoundthatthislowtemperatureprocesswasthermodynamicallyandkineticallypossible,andthecompositechromizedlayeronH13steel,withathicknessof3～6μm,consistedofthreesub-layers(bands),viz.theouterCr-richone,theintermediate(black)one,andtheinner,originalwhitelayer.Afterchromizing,theformerdiffusionlayerwasthickened.TheresultsofX-raydiffractionshowedthatthecompositechromizedlayercontainedsuchnitridesandcarbidesofchromiumasCrN,Cr2N,(Cr,Fe)23C6,and(Cr,Fe)7C3,aswellasplainα-(Fe,Cr).Ahighsurfacemicrohardnessof1450～1550HV0.025,whichismuchhigherthanthatobtainedbytheconventionalioncarbonitridingandionnitriding,wasobtained.Inaddition,anexcellentwearresistancewasgainedonthecompositechromizedlayer.

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