【作者】 沈杰；

【导师】 刘玉付； 张寿春；

【作者基本信息】 东南大学 ， 材料工程（专业学位）， 2017， 硕士

【摘要】 碳化硅纤维具有强度高、比模量高、密度小、化学性质稳定等优点,含铝碳化硅纤维具有优异的耐高温性,有望广泛应用于航空、航天、核能和化学化工等行业。国内外报道的铝源主要是乙酰丙酮铝、仲丁醇铝等,可供选择的铝源少,而且这些铝源挥发性高,容易使得配比不可控。因此本论文选择采用硬脂酸铝和8-羟基喹啉铝制备含铝碳化硅纤维具有重要的意义。本论文采用硬脂酸铝和8-羟基喹啉铝(Alq3)为铝源,利用温和的常压高温反应法,合成了聚铝碳硅烷先驱体(PACS),溶解8-羟基喹啉铝采用的溶剂是二甲苯、苯甲醇或者是N,N-二甲基甲酰胺(DMF);用傅里叶红外光谱(FT-IR)和X射线光电子能谱(XPS)分析了先驱体的组成;探索了铝元素含量和不同铝源对纤维成型性和力学性能的影响;利用扫描电子显微镜(SEM)、能谱分析(EDX)、X射线衍射(XRD)、透射电子显微镜(TEM)对表面形貌、成分、相组成等进行了表征;经过熔融纺丝、不熔化处理以及热解烧成,用硬脂酸铝制备了理论含铝量分别为0.lOwt%、028wt%的含铝碳化硅纤维,分别命名为1-SiC(Al)-1和l-SiC(Al)-2,用8-羟基喹啉铝制备了理论含铝量分别为0.06wt%、0.37wt%、0.84wt%的含铝碳化硅纤维,分别命名为 2-SiC(Al)-1、2-SiC(Al)-2和2-SiC(Al)-3;最后将用DMF作为铝源溶剂制备的2-SiC(Al)-2和不含铝碳化硅SiC(0)纤维在空气中经过高温热处理,通过表面形貌观察、相组成等对比分析了纤维在处理前后的变化。研究主要结论如下:(1)FT-IR分析发现,硬脂酸铝和8-羟基喹啉铝都分别参与了先驱体的合成反应,XPS分析确认了 2-SiC(Al)-3纤维的先驱体中的铝以Al-O键的形式存在;(2)用二甲苯作为8-羟基喹啉铝溶剂制备的2-SiC(Al)-1纤维直径约为12μm,平均强度1.6GPa。用苯甲醇作为8-羟基喹啉铝溶剂制备的2-SiC(Al)-2纤维和2-SiC(Al)-3纤维因为纺丝性较差,直径约25μm,平均强度小于l.OGPa。用DMF作为铝源溶剂制备的2-SiC(Al)-2纤维的先驱体平均无断头时间是2min,平均每次纺丝长度为440m,制备的2-SiC(Al)-2纤维直径为13μm,平均强度1.2GPa;(3)1-SiC(Al)-1纤维直径约12μm,平均强度为1.2GPa。l-SiC(Al)-2纤维由于先驱体纺丝性较差,直径约25μm,平均强度小于l.OGPa;(4)在空气气氛下热处理之后,2-SiC(Al)-2纤维表面比SiC(0)纤维更加光滑。在空气气氛下1000℃热处理50h之后,SiC(0)纤维出现了非常微弱的SiO2衍射峰,而2-SiC(Al)-2纤维几乎没有SiO2衍射峰,由此推测,铝元素起到了抗氧化的作用。更多还原

【Abstract】 As a high strength material with low density and superior chemical stability,SiC fibers,particularly aluminum-containing ones,have excellent high temperature resistance and are promising for wide applications in many industries such as aerospace,nuclear and chemical engineering.However,domestic and foreign researches on aluminum sources are mainly limited to aluminum acetylacetonate,aluminum tri-sec-butoxide and so on,volatilizing easily when heated,so it is difficult to control the aluminum content.It is,therefore,necessary to study the two news aluminum sources-aluminum tristearate and 8-Hydroxyquinoline aluminum salt(Alq3).In this thesis,synthesis of polyaluminocarbosilane(PACS)was carried out by using polycarbosilane and aluminum tristearate or 8-Hydroxyquinoline aluminum salt as start materials at high temperature under argon atmosphere.The solvents for Alq3 are xylene,benzyl alcohol or N,N-Dimethylformamide(DMF);The two types of PACS were melt-spun into green fibers,then cured in ambient air and pyrolysed to ceramic fibers,respectively.For aluminum tristearate,corresponding fibers,1-SiC(Al)-1 and 1-SiC(Al)-2,containing theoretically 0.1 Owt%and 0.28wt%aluminum respectively,were fabricated.And also,for Alq3,ceramic fibers,2-SiC(Al)-1,2-SiC(Al)-2 and 2-SiC(Al)-3,containing theoretically 0.06wt%,0.37%wt%and 0.84wt%aluminum respectively,were fabricated;This two PACS were analysied by Fourier Transform Infrared Spectroscopy analysis(FT-IR)and X-ray Photoelectron Spectroscopy analysis(XPS);Also investigations including the effects of contents of aluminum and the type of aluminum source on fiber tensile strength were carried out;Fiber morphology,microstructure and chemical composition were characterized by Scanning Electron Microscope(SEM)and Tunnelling Electron Microscope(TEM)with attached Energy Spectrum Analysis(EDX);X-ray Diffraction(XRD)was used for identifying phase compositions;In order to analysis the effect of aluminum,SiC(0)fiber,without aluminum,and 2-SiC(Al)-2 were exposed to high-temperature oxidation conditions,the changes of the fibers were identified by the surface structure and phase compositons.The main results are summarized as follows.(1)FT-IR test results show that the chemical reaction takes place between PCS and aluminum tristearate or Alq3.XPS tests show that aluminum element exists in the form of Al-O bond in the precursor of 2-SiC(AI)-3.(2)When xylene is chosen as the solvent for Alq3,the diameter of 2-SiC(AI)-I is 12μm,average strength is 1.6GPa.When benzyl alcohol is chosen as the solvent for Alq3.:the diameters of 2-SiC(Al)-2 and 2-SiC(Al)-3 are 25μm,average strength are less than 1.0GPa.When DMF is chosen as the solvent for AIq3,the precursor of 2-SiC(Al)-2 can spinning 2 minute every time,about 440m.The diameter of 2-SiC(Al)-2 is 13μm,average strength is 1.2GPa.(3)The diameter of 1-SiC(Al)-1 is 12μm,average strength is 1.2GPa.The diameter of 1-SiC(AI)-2 is 25μm,average strength is less than 1.0GPa.(4)After the high-temperature oxidation conditions,the surface of 2-SiC(Al)-2 is smoother than SiC(0),After the heat treatment:1000℃,50h,in the XRD pattern,SiC(0)has a weak SiO2 peak,while there is almost no SiO2 peak for 2-SiC(Al)-2,demonstrating the oxidation resistance of aluminum element.更多还原