SiAlCN型PDC陶瓷的研究进展

综述了SiAlCN型PDC（Polymer Derived Ceramics）陶瓷的制备、性能和应用。SiAlCN陶瓷有四类制备方法：粉末混合型：聚硅氮烷陶瓷前驱体与氧化铝粉末直接混合;粉末溶解型：含铝化合物粉末溶解于聚硅氮烷前驱体溶液中;单源前驱体型：铝原子通过适当的含铝化合物接枝在聚硅氮烷主链上,生成一种单源陶瓷前驱体聚铝硅氮烷;聚合物混合型：两种聚合物即聚硅氮烷与含铝聚合物共混;然后交联裂解制备陶瓷。与无Al的Si/C和Si/C/N体系相比,SiAlCN陶瓷具有优异的抗蠕变性、更好的抗氧化性和耐腐蚀性以及更好的导热性。因此,聚合物衍生的硅铝碳氮化物(SiAlCN)陶瓷是在高温和恶劣环境中应用很有潜力的材料。     

前驱体法制备Si-C-N-M基高性能陶瓷的研究进展

综述了聚合物前驱体热解转化法制备高性能Si-C-N-M基陶瓷的研究进展，着重介绍了3类Si-C-N-B基陶瓷前驱体（主链或侧基含有环硼氮烷或含硼杂环的聚硼硅氮烷、含硼聚硅氮烷和含硼聚硅基碳化二亚胺）及Si-C-N-Al基陶瓷前驱体。     

聚合物陶瓷先驱体材料的合成与应用

概述了作为陶瓷先驱体的四种聚合物f聚碳硅烷(PCS)、聚硅氮烷(PSZ)、聚硼氮烷(PBZ)以及聚硅氧烷(PSO)]的合成与应用,介绍了国内外对该类材料研究的最新进展,并针对先驱体裂解转化陶瓷工艺所存在的局限性以及不足,提出了今后的发展方向.     

先驱体转化法制备连续纤维增韧陶瓷基复合材料的研究进展

介绍了先驱体转化法制备连续纤维增强陶瓷基复合材料的研究现状,简要综述了聚碳硅烷、聚硅氮烷、聚硅氧烷3种先驱体的研究现状以及增强纤维的种类。分析了陶瓷基复合材料的应用现状和今后的研究方向。     

陶瓷前驱体聚硅氮烷的制备研究进展

综述了合成Si-C-N陶瓷前体聚硅氮烷的一些方法,着重介绍了含金属聚硅氮烷的制备方法,如:含钛聚硅氮烷、铝基聚硅氮烷、铁基聚硅氮烷、锆基聚硅氮烷、硼基聚硅氮烷、钇基聚硅氮烷、铜基聚硅氮烷的制备方法;其次介绍了使用共聚法、超支化法、倍半硅氮烷水解法制备聚硅氮烷的方法。     

碳硼烷基耐高温聚合物的研究进展

综述了碳硼烷基耐高温聚合物的研究背景、制备方法及结构特点；介绍了碳硼烷的合成方法和结构表征；对聚（碳硼烷-硅氧烷）、聚（碳硼烷-硅氧烷-乙炔基）和聚（芳基醚酮-碳硼烷）三类碳硼烷基聚合物的合成方法和性能进行了详细的介绍。目前研究表明：碳硼烷基聚合物具有极其优异的耐热及热氧化性能，在先进复合材料基体树脂、陶瓷前驱体、碳／碳复合材料的表面涂层和耐原子氧涂层等高技术领域具有广泛的应用。对碳硼烷基耐高温聚合物的发展前景进行了展望。     

陶瓷前驱体聚硅氮烷的应用研究进展(一)

综述了陶瓷前驱体聚硅氮烷在制备陶瓷涂层、陶瓷纤维、纳米材料、磁性陶瓷上的应用研究进展,指出了应用研究前景。     

陶瓷前体聚合物与热塑性嵌段共聚物的阻燃共混体

提高高分子材料燃烧时的成炭率是改善材料阻燃性的重要技术手段之一 ,而通过高聚物共混成炭则是这方面一个行之有效的方法。本文论述三种含硅陶瓷前体聚合物与热塑性嵌段共聚物的阻燃共混体。这三种陶瓷前体聚合物是聚碳硅烷 (PCS) ,聚硅苯乙烯 (PSS) ,及倍半硅氧烷 (SSO)。当它们与聚四次甲基醚乙二醇 -聚酰胺嵌段共聚物 (PTME -PA)或苯乙烯 -丁二烯 -苯乙烯嵌段共聚物 (SBS)或聚丙烯共混时 ,可提高共混体的成炭率及杨氏模量 ,降低释热速度 (HRR)及质量损失速度 (MLR) ,改善阻燃性。     

SiC/Si3N4陶瓷前驱体的合成

通过在六甲基环三硅氮烷中加入部分甲基氢二氯硅烷的氨解产物（ＣＨ３ＨＳｉＮＨ）ｘ,经氢化钾催化制备了聚硅氮烷;用热重分析法研究了其裂性能,考察了反应原料比例、溶剂对陶瓷影响;结果表明;溶剂和原料比例不仅影响硅氮烷的性能,且对陶瓷产率有重要影响。以四氢呋喃做溶剂可得到较高的陶民产率。     

SiC/Si_3N_4陶瓷前驱体的合成

通过在六甲基环三硅氮烷中加入部分甲基氢二氯硅烷的氨解产物 (CH3 HSiNH )x ,经氢化钾催化制备了聚硅氮烷 ;用热重分析法研究了其裂解性能 ,考察了反应原料比例、溶剂对陶瓷产率的影响 ;结果表明 :溶剂和原料比例不仅影响聚硅氮烷的性能 ,且对陶瓷产率有重要影响。以四氢呋喃做溶剂可得到较高的陶瓷产率。     

Preparation of ultra-high temperature SiC–TiB2 nanocomposites from a single-source polymer precursor

SiC–TiB₂ ceramic nanocomposites are valuable ultra-high temperature materials, which are rarely prepared from preceramic polymers. In this work, we synthesized SiC–TiB₂ nanocomposites from a new preceramic polymer called titanium- and boron-modified polycarbosilane (TB–PCS). The polymer structure was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The structure, composition, and morphology of the resulting ceramic products were investigated by FT-IR, X-ray diffraction, and transmission electron microscopy. The elements of titanium and boron were incorporated into the preceramic polymer, and nanoscale TiB₂ and β-SiC grains generated in situ were detected in the pyrolyzed ceramic products at temperatures higher than 1400 °C. The new preceramic polymer presents a novel approach to preparing SiC–TiB₂ nanocomposites.     

先驱体裂解制备陶瓷材料中存在的问题及解决方案

阐述了先驱体转化法的优劣性,并针对存在的问题提出了解决方案,着重阐述了添加活性填料的作用,介绍了活性填料的选择原则及活性填料控制先驱体裂解制备陶瓷材料应用特征,并就国内外的研究进展和未来发展方向进行了综述。     

有机硅先驱体在陶瓷成型中的应用

本文介绍用有机硅陶瓷先驱体(Organosilane Preceramic Polymer)成型非氧化物陶瓷制品的研究进展。着重介绍为提高先驱体热解陶瓷产率,降低烧结制品收缩率所采取的先驱体分子设计及成型、交联固化、烧成、烧结工艺的研究状况。     

Optimized preceramic polymer for 3D structured ceramics via fused deposition modeling

3D structured ceramics stemmed from preceramic polymers via additive manufacturing have attracted much attention recently. However, these polymers with high ceramic yield are so brittle that extrusion-based additive manufacturing techniques are hardly able to be utilized for assembling 3D structures. Herein, we developed a strategy to prepare feedstocks for these manufacturing techniques, i.e., utilizing a small amount of thermal-plastic polymer to optimize the preceramic polymer while good compatibility is required between the two polymers to ensure a homogeneous mixture. Polycarbosilane and polypropylene were selected as the representative materials. Polypropylene occupied a small proportion (≤5wt.%) and significantly improved the formability of the precursor. Three-dimensional SiC were obtained via fused deposition modeling combined with crosslinking and pyrolysis. The SiC ceramic filaments showed a mean tensile strength of 471 MPa. The strategy is also applicable to a large field of ceramic systems with corresponding precursor, such as sialon ceramic and multicomponent Si-based ceramics.     

SiOC Ceramic Foams through Melt Foaming of a Methylsilicone Preceramic Polymer

A process for the production of SiOC ceramic foams has been for the first time developed through melt foaming of a siloxane preceramic polymer with the help of a blowing agent, followed by pyrolysis under an inert atmosphere. The raw material consisted of a methylsilicone resin, a catalyst (which accelerated the cross-linking reaction of the silicone resin) and a blowing agent (which generated gas above 210°C). Methylsilicone resin foams were obtained through controlling the melt viscosity around 210°C, temperature where the blowing agent started to decompose, by varying the initial molecular weight of the preceramic polymer and the amount of the catalyst. The obtained SiOC ceramic foams exhibited excellent oxidation stability up to 1000°C, as shown by thermal gravimetric analysis (TGA). As expected, the mechanical properties of the SiOC ceramic foams varied as a function of their bulk density, possessing a flexural strength up to 5.5 MPa and a compression strength up to 4.5 MPa. The main steps in the process, namely foaming and pyrolysis, were analyzed in detail. The viscosity change was analyzed as a function of temperature by the dynamic shear measurement method. The pyrolysis process of foams was analyzed by TGA coupled with infrared spectroscopy (IR).     

先驱体转化法制备多孔陶瓷的研究现状

多孔陶瓷作为重要的陶瓷材料,广泛应用于冶金、化工等众多领域,其制备工艺的改进一直是研究重点。先驱体转化法是20世纪末提出的制备多孔陶瓷新型工艺,利用陶瓷先驱体高温裂解产生气体的特性,可将其作为粘结剂、骨料、发泡剂制备多孔陶瓷,具有成型工艺简单,烧成温度低等特点,拥有广泛的应用前景。本文主要从以上几个方面简要介绍先驱体转化法制备多孔陶瓷的工艺、结构和性能的研究现状。     

用有机聚合物连接碳化硅陶瓷及陶瓷基复合材料

用陶瓷先驱体有机聚合物连接陶瓷及陶瓷基复合材料是一种成本低廉、工艺新颖、可满足特殊高温条件下连接件要求的新型连接技术。介绍了近年来采用先驱体有机聚合物连接SiC及其复合材料的研究现状，重点对影响连接强度的因素进行分析，并提出相应的改进措施。由于该技术具有连接温度较低、连接过程简单、接头热应力小，连接件的热稳定性高等特点，因此它是陶瓷及其复合材料最有前途的连接方法之一。     

陶瓷先驱体催化裂解研究进展

有机聚合物衍生陶瓷技术具有聚合物分子可设计性强、成型容易和制备温度低等优点,已经成为陶瓷及其复合材料的主要制备技术之一。裂解是陶瓷先驱体实现从有机到无机转化的关键步骤,对目标陶瓷的组成、结构和性能有着决定性的影响。在陶瓷先驱体中添加过渡金属进行催化裂解,可以改变其裂解行为,进而调控和拓展裂解产物的结构和性能。本文从不同过渡金属对陶瓷先驱体的催化裂解作用入手,总结了陶瓷先驱体催化裂解的研究现状,探讨了催化机理,并就后续深化研究与应用提出了发展建议。     

Polymer-derived ceramic/graphene oxide architected composite with high electrical conductivity and enhanced thermal resistance

A low temperature method for the fabrication of architected ceramic composites contining graphene is developed based on the infiltration of lightweight graphene oxide (GO) micro-lattices with a preceramic polymer. Self-supported highly porous three-dimensional (3D) GO structures fabricated by direct ink writing are infiltrated with a liquid organic-polysilazane (a compound of Si, C, H, N), and subsequently pyrolyzed at temperatures of 800–1000?ºC to activate the ceramic conversion. These ceramic composites replicate the patterned GO skeleton and, whereas the graphene network provides the conductive path for the composite (electrical conductivity in the range 0.2–4?S?cm^?1), the ceramic wrapping serves as a protective barrier against atmosphere, temperature (up to 900?°C in air) and even direct flame. These structured composites also show hydrophobicity (wetting angle above 120°) and better load bearing capacity than the corresponding 3D GO lattice. The process is very versatile, being applicable to different liquid precursors.     

Fabrication of ceramic particles from preceramic polymers using stop flow lithography

Stop flow lithography (SFL) combines aspects of microfluidic and photolithography to continuously fabricate particles with uniform planar shapes as dictated by a mask. In this work we aim to expand the palette of materials suitable for SFL processing by investigating the use of UV-crosslinkable preceramic polymers to make ceramic particles. A commercially available methacrylated-polysiloxane was used as the preceramic polymer and was mixed with 2.5 wt% Irgacure 651 photoinitiator. A simple SFL system was assembled to continuously fabricate UV-crosslinked preceramic polymer particles in the shape of hexagons, triangles, and gears with diameters ranging from 100 to 200 μm and thicknesses of 74 μm +/- 4 μm. Particles were harvested from the excess preceramic solution, cleaned and then pyrolyzed at 1000 °C to transform them into silicon oxycarbide ceramic particles. Particle shape was maintained during pyrolysis despite a ～80 % linear shrinkage due to the removal of acryl and methyl side groups, as confirmed via FTIR. After pyrolysis the outer diameters of the SiOC particles ranged from 20 to 40 μm with thicknesses of 10 μm–12 μm. Pyrolyzed particles were successfully recovered and dispersed in water. This work demonstrates a robust path for the fabrication of ceramic particles with specific shapes from preceramic polymers via SFL.