耐超高温SiC(Al)纤维先驱体——聚铝碳硅烷纤维的研究

以聚硅碳硅烷(PSCS)与乙酰丙酮铝(Al(AcAc)3)为原料,在常压高温条件下反应制备出聚铝碳硅烷(PACS),经过熔融纺丝制备了PACS纤维.应用GPC、IR、XPS、29Si-NMR、27Al-NMR、TG、SEM、元素分析和增重等一系列分析,分别对PACS纤维的微观组成、结构以及性能进行了分析.研究结果表明,以原料质量配比为6∶100(Al(AcAc)3∶PSCS)合成的PACS化学式为SiC2.0H7.5O0.13Al0.018,数均分子量为1700左右,最适宜制备PACS纤维;PACS纤维中主要存在SiC4、SiC3H等结构,同时存在Si—O—Al键;在氮气气氛中,PACS纤维的陶瓷产率达到52%左右;预氧化处理,PACS纤维中Si—H键与空气中的氧反应形成Si—O—Si交联结构,较聚碳硅烷(PCS)纤维易于氧化,经过预氧化的PACS纤维陶瓷产率达到80%左右,是制备耐超高温SiC(Al)陶瓷纤维的合适纤维;用预氧化PACS纤维制备的SiC(OAl)纤维和SiC(Al)纤维抗拉强度高,耐高温性能好.

STUDY OF HIGH TEMPERATURE RESISTANT SiC(Al) FIBERS PRECURSOR——POLYALUMINOCARBOSILANE FIBERS

Polyaluminocarbosilane(PACS) was synthesized by reaction of polysilocarbonsilane(PSCS) with Al_(AcAc)_3,(AcAc:acetylacetonate) at normal pressure and high temperature,then PACS fibers were prepared through melt spinning of PACS.The composition and structure of PACS fibers were examined by measurements of element analysis,GPC,XPS,IR,()~(29)Si-Solid NMR and()~(27)Al-Solid NMR;the properties of PACS fibers were studied by TG,IR,weight gain and SEM.PACS synthesized through the reaction of Al(AcAc)_3 with PSCS by mass ratio of 6:100 was best fitting for preparing PACS fibers.Its empirical formula was SiC_(2.0)H_(7.5)O_(0.13)Al_(0.018) and the molecular weight was about 1700.The chemical structure unit included SiC_4,SiC_3H etc,and Si—O—Al bonds also existed in the PACS fibers.Under nitrogen atmosphere,the ceramic yield of PACS fibers was about 52%;during the curing process of PACS fibers in air,the Si—H bond reacted with oxygen,and Si—O—Si bond was formed.The ceramic yield of cured PACS fibers was about 80% and the properties of SiC(OAl) and SiC(Al) ceramic fibers were excellent.It was proved that PACS fibers were very fitting for making SiC(OAl) and SiC(Al) ceramic fibers.