简介:TiN-Al2O3compositepowderswithdifferentTiNcontents(0,10vol%,20vol%,30vol%and40vol%)werepreparedwithmicrometerTiNandα-Al2O3powder(theirpuritieswere99%)asstartingmaterialsbywetballmillingfor5h.TiN-Al2O3compositewerethenpreparedbypressingtheabovecompositepowders,dryingat200℃for12handfiringat1800℃for3hinnitrogenatmosphereinhot-pressingfurnace.TheinfluencesofTiNcontentonmechanicalpropertiesandelectricalconductivityofTiN-Al2O3compositeswerestudied.TheresultsshowedthatthemechanicalpropertiesofthecompositeincreasedwithTiNcontentincreasing,whiletheresistivityofcompositesdecreased.Acompositewith40%TiNhad498MPabendingstrength,4.285MPa·m1/2fracturetoughness,1.34×10-3Ω·cmresistivity.TheSEManalysisshowedthatthefineTiNcrystalsdistributedamongthecrystalboundaryofAl2O3matrix.Theybondedtogetherforminganet-likestructurewhichplayedaroleofrestrainingAl2O3grainsfromgrowingup,tougheningandstrengthening,sothemechanicalpropertiesofTiN-Al2O3compositewereenhanced.
简介:MMA经溴化加成、醚化、催化裂化制得双甲醋;单氰胺与二硫化碳在碱性条件下缩合、甲基化制备二氰醋,后与正丙胺缩合再与水合肼环合,丙三唑与苯甲醛醛缩;醛缩物在缚酸剂下与双甲醋催化闭环生成环合物。再在盐酸中水解去醛基得三唑嘧啶酮成品。分别选择car1#、cat2#为裂解和闭环催化剂,反应收率分别达91.59%,91.98%,91.1%,86.6%,69.7%,总收率46.32%,产品纯度99.53%。
简介:O'-sialon-ZrO2compositebasedonthecheapcommercialavailablezirconandsiliconasrawmaterialscanbeachievedbyusingreac-tionnitridationmethod,Moreattentionwasgiventothenitridingprocessandtheeffectofadditivesonit.Theexperimentalresultsshowthattherearetwonitridationpaths:oneisthedirectnitridationofsiliconpowderandtheotheristhroughthereactionbetweenthemedi-umcompoundZrSi2andthenitrogen.Theeffectsofadditionofcalciaandtheincorpora-tionofBNonthenitridingreactionwerealsoinvestigated,theprimitiveexperimentalresultsdemonstratedthatbothofcalciaandBNcoulddeterioratethenitridingdegree.