低温常压活化逆反应烧结β—SiN陶瓷的性能与结构研究

辽宁科技大学硕士论文AbstractAbstractIn order to resolve the problems of high production cost and low output in thetraditional making process of a-Si3N4 ceramic,the B-Si3N4 powder composed byflash combustion nitriding method was used as the raw materials,adding Al2O3,Y2O3and metal Al as sintering adis,moldinged by isostatic pressure method,the reversereaction sintering at normal pressure was used for making low cost and high quality B-Si3N4 ceramics,which would expand the field of application of Si3N4 ceramicenormously.The reverse reaction sintering process is a new concept raised according to theprocess mechanism.The clou is to sacrifice a few of Si3N4 for forming a neonatalcombined phase of Si-Al-O-N system by oxidation reaction of Si3N4.The key is controlthe oxidation of Si3N4 by regulate the oxygen partial pressure,not only avoiding theexcessive oxidized,but also achieve active sintering.It has been studied as follow:discussing the feasibility of using the reverse reactionsintering to prepare B-Si3N4 ceramic by thermodynamics analyse;ascertaining theoptimal oxygen partial pressure and sintering system by comparing the sinteringproduce properties of different system which sintered in vary oxygen partial pressure at1550 C,and the influence of content of Al2O3 or Y203 on sintering properties;discussing the influence of nano-Al2O3 and its content on sintering properties sintered at1600C,and the influence of content of Al powder sintered at 1650C;finally,discussing the influence of temperature on sintering properties by the sinteringexperiments at1550、1600、1650C.The results indicated that:It was feasible using the reverse reaction sintering toprepare B-Si3N4 ceramic.The optimal oxygen partial pressure was 0.002MPa,theoptimal sintering system was Si3N4-Al203-Y203-Al,the optimal content of Al2O3 wasw%=10.The more Y203 was added,the more excellent were the properties whensintered at 1550C.The contribution of nano-Al2O3 to cold crushing strength wasenormous,and the contribution was enhanced with the increasing of the content whensintered at 1600C.The sintering properties was best when the addition of Al powderw%2 and sintered at 1650C.The properties of the produce were improved with therising of the sintering temperature from 1550 to 1650C.The volume density achieved