【摘要】 以硅树脂RSN-6018为陶瓷前驱体聚合物、偶氮二甲酰胺为发泡剂、聚甲基丙烯酸甲酯为造孔剂、氯化钴为金属离子催化剂，分别采用前驱体自发泡、发泡剂法以及添加造孔剂法，在Ar气氛中于1400℃高温裂解转化制备分级多孔的硅氧碳（SiOC）多孔陶瓷。同时引入金属离子催化剂促进SiOC多孔陶瓷中原位生长碳化硅（SiC）纳米线。研究了不同成孔工艺得到的SiOC多孔陶瓷的孔结构与性能，探讨了催化剂对SiC纳米线的原位生长以及SiOC多孔陶瓷力学性能的影响规律。研究表明，不同成孔工艺制备的SiOC多孔陶瓷的孔结构具有明显差异，进而对性能影响较大；氯化钴的添加促进了SiC纳米线的原位生长，提高了SiOC多孔陶瓷的力学性能；以聚甲基丙烯酸甲酯微球（PMMA）为造孔剂、氯化钴为催化剂制备的SiOC多孔陶瓷的显气孔率为46.3%，耐压强度最高达29.6 MPa，与未添加催化剂的样品相比提升了31.5%。更多还原

【Abstract】 The precursor polymer conversion method is a new method for preparing porous ceramics. It has more excellent characteristics such as low preparation temperature, designable composition and structure, and easy molding of complex-shaped components, which is significantly better than traditional methods. Among them, SiOC porous ceramics are a type of material that has attracted much attention in the field of materials science. It has excellent properties such as high temperature resistance, thermal shock resistance, corrosion resistance, and oxidation resistance. It is used in high-temperature gas or molten metal filtration, catalyst carriers, heat exchangers, etc. The field has important application value and is also one of the most potential materials. However, different application fields put forward different requirements on the pore structure and performance of porous ceramics. The pore structure obtained by different processes is different. Even under the same apparent porosity conditions, the pore morphology, pore size and distribution are also different. In turn, it has a great impact on the performance of porous ceramic products. Therefore, how to design the pore structure and parameters of SiOC porous ceramics and select the corresponding preparation process is a key issue. This article used silicone resin RSN-6018 as the ceramic precursor polymer, azodicarbonamide(ADC) as the foaming agent, polymethyl methacrylate(PMMA) as the pore former, and cobalt chloride(CoCl2·6H2O) as the metal ion. catalyst. Precursor self-foaming, foaming agent method, and pore-forming agent method were used respectively to prepare hierarchical porous silicon-oxy-carbon(SiOC) porous ceramics by pyrolysis and conversion at 1400 ℃ in Ar atmosphere. In addition, in order to improve the mechanical properties of SiOC porous ceramics, adding one-dimensional reinforcing materials(SiC whiskers, carbon nanotubes or SiC nanowires) was an effective method. However, external reinforcement materials had problems such as difficulty in uniform dispersion, poor interface bonding, and limited improvement performance. In-situ generation of SiC nanowire-reinforced SiOC porous ceramics was an ideal process that could greatly increase the specific surface area of SiOC porous ceramics and improve the mechanical properties, so that it had a wider range of applications in catalyst carrier, pollutant removal and high-temperature gas filtration. In this paper, the introduction of metal ion catalysts promoted the in-situ growth of silicon carbide(SiC) nanowires in porous SiOC ceramics. The pore structure and properties of SiOC porous ceramics obtained by different pore-forming processes were studied, and the influence of the catalyst on the in-situ growth of SiC nanowires and the mechanical properties of SiOC porous ceramics was discussed. The studies showed that the pore structure of SiOC porous ceramics prepared by different pore-forming processes was significantly different, which had a greater impact on performance; among them, the self-foaming of the precursor polymer was mainly irregular pores with uneven pore size distribution, and some were through. The pore size was 20～50 μm, the pore walls were relatively dense, with a small number of small pores. The spherical closed cells with a pore size of about 50 μm obtained by the foaming method and had a window structure, the pore walls were loose and cracks appear, and a large number of small pores appeared small pores; while SiOC porous ceramics prepared by adding PMMA were mainly spherical closed pores with a pore size of 30～50 μm. The pores were evenly distributed, the pore walls were relatively dense, and small pores were formed, forming a SiOC with a hierarchical pore structure porous ceramic. Further observation of the microstructure of SiOC porous ceramics revealed that a small number of nanowires were generated in the pores of the porous ceramics. For SiOC porous ceramics prepared by the process of self-foaming and adding pore formers, the morphology and number of SiC nanowires were not much different, with a diameter of 100～200 nm and a length of more than 50 μm, all showing varying degrees of bending. SiC nanowires in SiOC porous ceramics prepared by the blowing agent process were mainly in the form of beads. In order to further improve the number and morphology of SiC nanowires, cobalt-based catalysts were added in different pore-forming processes. It was found that the number of SiC nanowires in SiOC porous ceramics increased significantly, the aspect ratio increased, and the linear and curved nanowires interlaced each other into a three-dimensional network structure, which showed that the addition of cobalt chloride catalyst promoted the in-situ growth of SiC nanowires. In addition, after three different pore-forming processes were added with catalysts, the compressive strength of the samples increased significantly, increasing by 22.4%, 34.1% and 31.5%, respectively. SiC nanowires effectively improved the mechanical properties of SiOC porous ceramics, and among them, SiOC porous ceramics prepared with PMMA as pore former and cobalt chloride as catalyst had the best performance, with an apparent porosity of 46.3% and the highest compressive strength of 29.6 MPa, an increase of 31.5% compared with the sample without added catalyst.更多还原