先驱体转化含铝碳化硅陶瓷纤维的制备研究进展

先驱体转化含铝碳化硅陶瓷纤维具有高强度、高模量、耐高温、抗氧化等特性,是高温陶瓷基复合材料理想的增强体之一。基于含铝Si C陶瓷纤维的制备工艺路线,从聚铝碳硅烷(PACS)的合成方法及其机理、PACS纤维不熔化处理方法和控制Si(Al)C陶瓷纤维缺陷的研究现状方面综述了先驱体转化含铝Si C陶瓷纤维制备的最新研究进展。讨论了现有PACS合成路线和不熔化处理工艺的优缺点。此外,围绕含铝Si C陶瓷纤维的制备路线,认为后续可持续关注的主要有探索新的PACS合成路线、高效不熔化处理方法和提高Si(Al)C陶瓷纤维力学性能的方法等方面。     

先驱体转化法制备碳化硅纤维

简述了碳化硅纤维的发展简史 ;指出了优良的先驱体的特点和合成方法 ;为获得优异的高温性能的碳化硅纤维 ,应使先驱体聚合物中的n(C) /n(Si)比尽量接近 1 ,或引入金属元素或烧结助剂 ;介绍了影响碳化硅纤维力学性能的若干因素和目前已商品化的几种碳化硅陶瓷纤维的典型性质。     

SiBN(C)陶瓷纤维先驱体的表征及熔融纺丝

以B(NHCH3)3和Si(NHCH3)4为小分子先驱体,在一定条件下通过共缩聚反应得到聚硅硼氮烷,经熔融纺丝得到SiBN(C)陶瓷先驱体纤维;采用红外光谱、核磁共振、元素分析等手段研究了小分子先驱体的配比对聚硅硼氮烷结构的影响.结果表明:聚硅硼氮烷存在B-N六元环、Si-N、Si-N-B、N-H等主要官能团,熔融纺丝...     

SiBN陶瓷纤维的脱碳工艺研究

以三氯化硼、六甲基二硅氮烷、三氯硅烷和甲胺为原料,采用多步法合成、聚合得到可纺性良好的聚硼氮硅烷(PBSZ)前驱体,通过熔融纺丝得到前驱体纤维,再经热化学交联得到不熔化纤维;在氨气/氮气(NH_3/N_2)气氛下进行热解脱碳(C)处理制备了硅硼氮(SiBN)陶瓷纤维;研究了NH_3/N_2体积比、气体流量、升温速率、保温时间以及热解温度等对SiBN纤维中C含量的影响,分析了PBSZ的脱C机理。结果表明:较优的热解工艺是NH_3/N_2体积比为3∶1,升温速率为0.5℃/min,600℃和1 000℃分别保温3 h,气体流量为100 m L/min,可制备C质量分数小于0.1%的Si BN陶瓷纤维;NH3对脱C具有积极作用,在热交联反应、自由基反应和脱氢偶合反应的综合作用下,C主要以甲胺和甲烷的形式脱除。     

SiBN先驱体陶瓷化行为及结构稳定性分析

SiBN陶瓷是重要的结构陶瓷和功能陶瓷,在航空和航天领域具有广泛的应用前景,本文针对不同温度制备的SiBN陶瓷的高温结构稳定性及抗氧化性能开展研究。采用TG、FTIR和XRD技术对SiBN先驱体室温至1500℃温域的热解行为、裂解产物组分和结构进行了表征,采用FTIR和XRD技术对SiBN陶瓷氧化行为和氧化机理进行了分析。研究表明,SiBN陶瓷先驱体热解过程主要发生在200℃至800℃范围,该阶段实现了SiBN陶瓷先驱体从有机物向无机物的转化,SiBN陶瓷在室温至1500℃宽温域惰性气氛下具有优异的结构稳定性。但在1500℃氧化产物失重高达17.37%,并伴随明显的组分和结构变化,导致复合材料性能下降或者结构失效。     

SiC(Nb)陶瓷纤维先驱体聚铌碳硅烷的合成与表征

为了提高SiC陶瓷纤维的综合性能,利用聚二甲基硅烷热解制得的产物液态聚硅烷(liquid polysilane,LPS)与五氯化铌(NbCl5)反应,制各了含铌SiC陶瓷纤维的先驱体聚铌碳硅烷(polyniobiumcarbosilane,PNCS).研究表明:反应过程中存在LPS裂解重排反应,Si-H键在反应中显示出很高的活性,FNCS分子量的增加是LPS形成的Si-H键与NbCl5发生交联反应的结果,用LPS与NbCl5为原料不但能使铌元素成功地引入到先驱体中并且分布均匀,而且由于其成本比其他原料相对低廉便于大批量合成.利用PNCS制备的Si-Nb-C-O陶瓷纤维平均强度为1.8GPa,平均直径为12 μm,耐高温性能优异.     

用聚碳硅烷制备柔性疏水型碳化硅纤维毡(英文)

以聚合物先驱体转化法用陶瓷工艺与静电纺丝技术相结合制备了碳化硅(SiC)陶瓷纤维毡。以聚碳硅烷为先驱体,利用静电纺丝技术制备先驱体原纤维毡。原纤维毡经过低温交联和1 000℃以上热解,得到SiC纤维毡。当温度达到1 200℃时,纤维毡为多晶态,保持典型的三维网络结构,纤维直径约为1.1mm。电子探针分析表明,纤维毡化学组成为Si、C、以及少量O元素。SiC纤维毡具有良好的疏水性,疏水角大于130°。1 000℃热解制备的SiC纤维毡的拉伸强度为0.6MPa,断裂伸长率为45%,可应用于高温极端环境。     

聚合物先驱体转化法制备陶瓷MEMS器件

简述了聚合物先驱体转化陶瓷(PDC)法在制备陶瓷纤维、陶瓷涂层和陶瓷粘接等方面的应用,重点介绍了PDC法在微机电系统(MEMS)器件制造中的发展概况。耐高温MEMS的发展面临两大挑战:高温材料的选择和发展合适的微加工技术。指出了传统加工技术制备陶瓷MEMS的不足,着重介绍了PDC法制备陶瓷MEMS的优缺点。以国外采用PDC法制备陶瓷MEMS的几种典型器件为例,指出该方法在制备陶瓷MEMS器件中存在的问题和未来的发展方向。     

陶瓷纤维技术前沿探秘

陶瓷纤维是一种集传统绝热材料、耐火材料优良性能于一体的纤维状轻质耐火材料,陶瓷纤维具有重量轻、耐高温、热稳定性好、导热率低、比热小及耐机械震动等优点,因而其产品涉及各领域,发展前景十分看好。本文分别介绍了陶瓷纤维的种类及性能特点,陶瓷纤维的结构性质和制造方法;陶瓷纤维的主要用途和应用范围;以及陶瓷纤维在热工窑炉中的应用技术;同时指出了陶瓷纤维的发展趋势。     

Si-Al-C-N陶瓷先驱体研究进展

Si-Al-C-N陶瓷具有较好的耐高温、抗氧化以及抗蠕变等性能。综述了近年来Si-Al-C-N陶瓷先驱体及其裂解陶瓷的研究进展,介绍了合成Si-Al-C-N先驱体的3种主要方法及相应先驱体及其裂解陶瓷的性能,并对今后的研究方向做出了展望。     

Synthesis and pyrolysis mechanism of a novel polymeric precursor for SiBN ternary ceramic fibers

A novel polymeric precursor polyborosilazane (PBSZ) for SiBN ternary ceramic fibers was successfully synthesized from trichlorosilane (HSiCl₃), boron trichloride (BCl₃) and hexamethyldisilazane (HDMZ) by a simple one step reaction process. The chemical structures and ceramic yield of the PBSZ precursors were investigated by NMR spectroscopy, FT-IR and TGA. The preparation of PBSZ fibers was conducted in a lab-scale melt-spinning equipment at a spinning speed of 130 m/min. SiBN ternary ceramic fibers were obtained after the non-fusible treatment and pyrolysis of PBSZ fibers in an NH₃ atmosphere. The pyrolysis mechanism, high-temperature behavior and morphologies of the SiBN ternary ceramic fibers were investigated by NMR, XRD, TEM and SEM. The obtained SiBN ternary ceramic fibers had good flexibility, and possessed a tensile strength of 0.84 GPa with a diameter of ∼18 μm. Furthermore, these SiBN ceramic fibers exhibited excellent thermal stability, and maintained the amorphous state up to 1600 °C.     

Effects of hydrolysis of precursor on the structures and properties of polymer-derived SiBN ceramic fibers

In this paper, polyborosilazane precursor was synthesied from HMDZ, HSiCl₃, BCl₃ and CH₃NH₂ using a multistep method. By controlling the storage conditions, parts of the polyborosilazane fibers were hydrolyzed. FT-IR, NMR, XRD, TEM and monofilament tensile strength test were employed to study the effects of hydrolysis of precursor on the structures and properties of polymer-derived SiBN ceramic fibers. FT-IR and NMR results indicate that Si-N group in PBSZ reacts with H₂O to form Si-O-Si group. After pyrolysis reaction at 1400℃, Si-O-Si group will finally transformed into highly ordered cristobalite and β-quartz, resulting in formation of the wrinkled surface of the obtained SiBN ceramic fiber. The strip-like defects on fiber surface, according to monofilament tensile strength test, had a significant effect on mechanical property of the obtained SiBN ceramic fiber and caused no increase in fiber tensile strength of hydrolytic polyborosilazane fiber before and after pyrolytic process.     

硅硼氮纤维前驱体聚合物的扩链反应改性

以柔性链遥爪聚合物[双(3-氨丙基)封端的聚二甲基硅氧烷(BTA-PDMS)]为扩链剂,对聚硅硼氮烷进行扩链反应改性,既可以提高其相对分子质量,又在刚性分子链中引入柔性链段,这显著改善了前驱体聚合物纤维的柔韧性,有望实现易退绕的目的。     

Pyrolysis of polyborosilazane and its conversion into SiBN ceramic

Abstract

The polyborosilazane was prepared by coammonolysis of boron trichloride and methyldichlorosilane with hexamethyldisilazane. The decarburisation process of the polyborosilazane under ammonia was studied. The results suggested carbon was effectively removed under ammonia and the removal of carbon mainly occurred during the temperature range of 400–600°C. After pyrolysed at 900°C under ammonia, the carbon content was only 0·29 wt-%. Further heat treatment at 1500°C under argon yielded SiBN ceramic. The structure and morphological properties of SiBN ceramic were studied by solid ²⁹Si nuclear magnetic resonance, X-ray diffraction and scanning electron microscopy. The results showed that the SiBN ceramic was amorphous and possessed a smooth surface. The contents of boron, silicon and nitrogen in the SiBN ceramic are 10·9, 42·6 and 38·48 wt-% respectively.     

Effects of boron content on the microwave-transparent property and high-temperature stability of continuous SiBN fibers

Owing to their high-temperature stability and microwave-transparent properties, SiBN fibers are promising reinforcement materials for microwave windows or radomes in harsh environments. This work investigates the high-temperature properties of continuous SiBN fibers with different boron contents. Compared with Si₃N₄ fibers, the SiBN fibers demonstrated superior high-temperature stability, retaining their original tensile strength up to 1600°C with a smooth surface and amorphous structure. The boron-containing microstructure improved the microwave-transparent properties of the SiBN fibers by decreasing their dielectric constant and loss. The values were stabilized at temperatures up to 1200°C. The high-temperature stability and microwave transparency of the SiBN fibers were likely contributed by the synergistic effect of the amorphous BN phase and the Si–N–B networks (the main existing state of the boron atoms).     

氮化硼陶瓷纤维的制备与应用

氮化硼陶瓷纤维是一种正在发展的新型高性能材料,然而传统的高温法很难制备高质量的氮化硼陶瓷纤维材料,只能通过前驱体转化法实现。概述了氮化硼陶瓷纤维的合成路线以及各种前驱体制备氮化硼陶瓷纤维的优缺点,并对前驱体法制备氮化硼陶瓷纤维的发展趋势做了展望。     

Zirconia-alumina multiphase ceramic fibers with exceptional thermal stability by melt-spinning from solid ceramic precursor

Zirconia-alumina multiphase ceramic fibers with 80 wt% (Z80A20 fiber) and 10 wt% (Z10A90 fiber) proportions of zirconia were prepared via melt-spinning and calcination from solid ceramic precursors synthesized by controllable hydrolysis of metallorganics. The zirconia-alumina multiphase fibers had a diameter of about 10 µm and were evenly distributed with alumina and zirconia grains. The Z80A20 and Z10A90 ceramic fibers had the highest filament tensile strength of 1.78 GPa and 1.87 GPa, respectively, with a peak value of 2.62 GPa and 2.71 GPa. The Z80A20 ceramic fiber has superior thermal stability compared to the Z10A90 ceramic fiber and a higher rate of filament strength retention due to the stability in grain size. After heat treatment at 1100 °C, 1200 °C, and 1300 °C for 1 h respectively, the filament tensile strength retention rate of Z80A20 ceramic fibers was 87 %, 80 %, and 40 %. While Z10A90 ceramic fiber was fragile after being heated at 1300 °C. The results showed that the high zirconia content facilitated the fiber's thermal stability.     

热解含铁聚硅氧烷原位生长硅氧碳纤维制备硅氧碳复合材料

将铁氯化物混入聚硅氧烷前驱体进行交联成型和热解,利用热解中在聚硅氧烷中形成的孔隙和在孔隙中形成的铁颗粒为催化剂,在硅氧碳陶瓷基体中原位生长出硅氧碳纳米纤维,制备出硅氧碳陶瓷和硅氧碳纤维复合材料。用扫描电子显微镜观察材料断面,结果显示：在硅氧碳陶瓷基体中生长出纳米纤维,部分纤维取向分布,纤维紧贴于硅氧碳陶瓷基体,二者呈良好结合;能谱分析显示纤维中含硅、氧和碳,证实其为硅氧碳。所制得的硅氧碳陶瓷和硅氧碳纤维的复合结构不同于通常热解纯聚硅氧烷形成的单相的硅氧碳结构,在硅氧碳基体中的硅氧碳纤维是在聚硅氧烷前驱体中引入的铁催化剂在热解过程中通过催化聚硅氧烷一维生长形成的,该过程可用于发展一步法原位制备纳米纤维前驱体陶瓷复合材料。     

氧化铝基连续陶瓷纤维的发展现状

介绍了国内外氧化铝基连续陶瓷纤维的研究现状,并阐述了它在航天领域、机械制造领域和过滤材料方面的应用现状和发展前景。