简介：Ni-dopedphenolresinwaspreparedwith1∶100massratioofNi(NO_3)_2·6H_2Otothermosettingphenolresintooptimizethestructureandpropertiesofpyrolyticcarbonderivedfromphenolresinandincreaseitscarbonyield.Thespecimenswerecuredat200℃andcarbonizedunderdifferentatmospheres(carbon-embeddedatmosphereandAratmosphere)andatdifferenttemperatures(600,800,1000and1200℃)for3h,respectively.Thecarbonyieldwasmeasured.ThermaldecompositioncharacteristicsofNi-dopedphenolresin,andtheoxidationresistance,phasecompositionandmicrostructureofpyrolyticcarbonwerecharacterizedbydifferentialscanningcalorimetry,X-raydiffraction,energydispersivespectroscopy,scanningelectronmicroscopyandtransmissionelectronmicroscopy.TheresultsshowthatthecarbonyieldofNi-dopedphenolresincarbonizedat800or1000℃isincreasedsignificantly,comparedwiththatwithoutanydopants.ThegraphitizationdegreeofpyrolyticcarbonstructurederivedfromNi-dopedphenolresinincreaseswiththeincreaseofcarbonizationtemperature.Themassivemulti-wallcarbonnanotubesof50-100nmindiameterandofmicrometrescaleinlengtharegeneratedat1000℃.Comparedwiththecarbonembeddedatmosphere,carbonnanotubescanbemoreeasilygeneratedinAratmosphere,resultinginhighercarbonyieldanddegreeofcrystallinityofthepyrolyticcarbonderivedfromNi-dopedphenolresin.TheoxidationresistanceofthepyrolyticcarbonderivedfromNi-dopedphenolresinat1200℃isimprovedsignificantlyanditshighestoxidationtemperatureisincreasedbyabout84℃,comparedwiththatfromNifreephenolresin.

简介：InthispaperwepresenttheresultsofstudiesonmakingMgOzirconiasinteredparts(intendedtobeusedasmeteringnozzlesincontinuouscastingofsteel)frommonocliniczirconiaandMgOpowdersviaagranulationprocess.Thepartswerepressedandsinteredunderdifferentconditions,andanalysedforphysicalproperties,microstructureandphasecomposition.WefoundastronginfluenceoftheMgOconcentrationandthesinteringcycle,especiallythecoolingrateonthethermalshockresistance.Thepaperconcludeswithrecommendationsfortheproductionofzirconiameteringnozzlesinaneconomicway.