简介:Thehydrationoftricalciumaluminate(C3A)hasasignificanteffectontheeffectivenessofcement-basedsystems.Inaddition,thecarbonationofhydrationproductsofC3Aisparticularlyimportantinrespectofdurabilityperformance.ThepresentworkinvestigatesthehydrationandcarbonationreactionsofC3AandthechangesinducedbythepresenceoftheheavymetalionssuchasZn2+,Pb2+,Cu2+andCr3+byX-raydiffractometry(XRD).DuringhydrationofC3A,gehlenitehydrate,hydrogarnet,calciummonoaluminate(C4AHx)andcalciumcarboaluminateweredetectedinC3ApastesexcepttheZn2+dopedpaste,wherehydrogarnetdidnotform.Theexaminationsrevealedthatheavymetalscoexistedwithgehlenitehydrate,calciummonoaluminate(C4AHx)andcalciumcarboaluminate,inhibitingtheformationofhydrogarnet.HydratingC3Awasliabletobecarbonatedonexposuretoairandcarbondioxide,especiallyinthepresenceofheavymetals,resultingintheformationofcarboaluminateand/orcalciumcarbonate.Thepresenceofheavymetalsin-fluencedthepolymorphismofcalciumcarbonate,ndicatingthatheavymetalscouldco-precipitatewithcalciumtoformacarbonatesolidsolution.
简介:ThemagnesiabasedcurablespecimenswithdifferentSi3N4contentswerecastedusingsinteredmagnesite(w(MgO)=95%)asstartingmaterial,SiO2micro-powderasbinder,0.3%,4%and5%β-Si3N4powderreplacingtheequaladditionofmagnesiapowderrespectively.Theslagresistancetestwascarriedoutat1550℃for3husingBaosteeltundishslagandstaticcruciblemethod.Theresultindicatesthat:introducingSi3N4couldobviouslyimprovetheslagresistanceofMgObasedcastable,whichincreasedwithincreasingSi3N4.DenseSiO2sinteredlayerformedonthesurfaceofmagnesiabasedcastablebecauseoftheoxidationofSi3N4addition,whichcanpreventthefurtherslagpenetration.Inthedeepinnerofcastable,thepartial-pressureofoxygenwasverylow,soSi3N4canexiststably.Meanwhileinreducingatmosphere,Si3N4washardtobesintered,whichresultedinthelooseinteriorstructureofMgObasedcastable.
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简介:AnO'-Sialon-Al2O3compositerefractorywaspreparedbyinsitureactionofSi3N4-ZrSiO4-Al2O3mixturewithfusedaluminaaggregates.Densification,insitureactionprocedureandmicrostructureofthematerialwereinvestigatedbymeansofX-raydiffraction,opticalandscanningelectronicmicroscopesandEDAX.
简介:1.概述今年前三季度,黄磷市场库存量比去年有所减少,主要是由于一是截止到去年年底的库存量很少;二是关税增收前,下游磷酸、三聚磷酸钠企业为提前执行完出口订单,选择了加大采购,使得市场上整体库存量减少;三是今年雨季推迟,降雨量同比往年有所减少,使得云南地区在7月份出现了少有的限电现象,并持续了近20天;四是由于今年节能减排检查力度加大,各地为完成减排任务,不得不限制黄磷等高耗能产业的开工率,如云南省今年把黄磷产量限制在33万吨以内,并根据各企业的产能情况,分解到每个企业,严格控制黄磷产量,不得无计划的生产,因此综合以上因素分析,今年1-8月份黄磷产量比去年同期有所减少,库存量也降到了近3年来的最低点。
简介:Si3N4powderandhot-pressedSi3N4ceramicsaddedwithAl2O3areusedforinvestigatetheiroxidationbehviorinairandnitrogenatmosphere(withoxygenpartialpressurePO2=1-10Pa),TheoxidationproductsofSi3N4areexaminedbychemicalanalysi,X-raydiffraction(XRD)andXPSmethod,Also,thermodynamiccalculationismadetoanalyzeoxidationbehaviorofSi3N4.TheresultsshowthatonlypassiveoxidationwilloccurwhenSi3N4isoxidizedinairathightemperature,whereasinN2athightemperature,theactiveoxidationisdominantinspiteoftheexistenceofalittlepassiveoxidation.
简介:截至10月,超过4000美国人正在等待接受心脏移植。随着心脏的衰竭,这些患者没有其他选择;心脏组织,不像其他身体部位,一旦被损坏是无法自身治愈的。幸运的是,卡内基·梅隆大学一个团队最近的研究,可能有一天将不再需要移植来修复受损的器官。"我们已经能够获得冠状动脉的MRI图像和胚胎心脏的3D图像,并且利用非常柔软的材料,如胶原蛋白、藻酸盐和纤维3D生物打印他们,使其具有前所未有的分辨率和质量,"卡内基·梅隆大学材料科学与工程和生物医学工程副教授AdamFeinberg说。"正如Feinberg教授在生物印刷工作中出色展示的那样,我们CMU的
简介:Themicrostructureandslagerosionfractaldimensionofreactioninterfaceofβ-Sialon-Al2O3brickusedin300MtironladleofBaosteelhavebeenstudiedbySEMandXRD.Theresultsindicatedthatβ-Sialon-Al2O3brickexhibitedexcellentslagresistance.Themainwearmechanismofβ-Sialon-Al2O3brickismainlyfromthespallingcausedbythermalmechanicalstressandattackedbyslagsecondly.