简介：AnewapproachtoproducesuperfineWC-Copowderbydirectreductionandcarbonizationisproposed.Water-solublesaltscontainingWandCowereusedasrawmaterials.Tungstenandcobaltoxidepowder(CoWO4/WO3)wasfirstformedbyaspray-pyrolysistechnique,whichwasthenmixedwithcarbonblackandconvertedtoWC-Cocompositepowderat950℃for4hinN2atmosphere.Theresultingpowderhasaparticlesizeof100-300nm.

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：Unusualcarbonaceousmatter,termedherechiemite,composedofmorethan90%CfromtheAlpineForelandatLakeChiemseeinBavaria,southeasternGermanyhasbeeninvestigatedusingopticalandatomicforcemicroscopy,X-rayfluorescencespectroscopy,scanningandtransmissionelectronmicroscopy,high-resolutionRamanspectroscopy,X-raydiffractionanddifferentialthermalanalysis,aswellasbyδ13Cand14Cradiocarbonisotopicdataanalysis.Inthepumice-likefragments,poorlyorderedcarbonmatterco-existswithhigh-orderingmonocrystallineα-carbyne,andcontainssubmicrometer-sizedinclusionsofcomplexcomposition.Diamondandcarbyneaddtothepeculiarmixofmatter.TherequiredveryhightemperaturesandpressuresforcarbyneformationpointtoashockeventprobablyfromtherecentlyproposedHoloceneChiemgaumeteoriteimpact.Thecarbonmaterialissuggestedtohavelargelyformedfromheavilyshockedcoal,vegetationlikewood,andpeatfromtheimpacttargetarea.Thecarbonization/coalificationhighPTprocessmaybeattributedtoastrongshockthatinstantaneouslycausedthecompleteevaporationandlossofvolatilematterandwater,whichneverthelesspreservedtheoriginalcellularstructureseenfossilizedinmanyfragments.Relativelyfreshwoodencapsulatedinthepurportedstronglyshockedmatterpointtoquenchedcarbonmeltcomponentspossiblyimportantforthediscussionofsurvivaloforganicmatterinmeteoriteimpacts,implyinganastrobiologicalrelationship.

简介：