KD-S和KD-Ⅱ SiC_f/SiC复合材料的制备、微观结构及性能（英文）
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摘要
以KD-S和KD-Ⅱ型碳化硅(SiC)纤维编织件为增强体,通过先驱体浸渍裂解工艺制备了以热解炭(PyC)为界面涂层的三维(3D)结构SiC_f/SiC复合材料,系统研究了SiC_f/SiC复合材料的微观结构及性能间的关系。结果表明:KD-S和KD-Ⅱ型SiC纤维均具有晶粒尺寸为8～15 nm的多晶结构;两种SiC_f/SiC复合材料的断口表面均出现了纤维拔出现象,说明两种SiC纤维增强的SiC_f/SiC复合材料均具有典型的伪塑性断裂行为。KD-S SiC_f/SiC复合材料的弯曲强度、弹性模量和断裂韧性分别达到(955.0±42.8) MPa,(110.3±1.7) GPa和(28.5±2.8) MPa·m~(1/2),明显高于KD-ⅡSiC_f/SiC复合材料,这归因于近化学计量比的KD-S型SiC纤维具有较高的模量和耐温性能。由于KD-S和KD-Ⅱ型SiC纤维的结构及成分差异,导致KD-S型SiC纤维表面的PyC界面涂层呈现光滑的多层有序结构,而KD-Ⅱ型SiC纤维表面的PyC为疏松颗粒状结构。
Three-dimensional(3 D) SiC/SiCf composites were fabricated by a polymer impregnation and pyrolysis(PIP) method using 3 D four directional braided preforms from two kinds of SiC fibers as the reinforcements and liquid polycarbosilane as the SiC precursor. Both kinds of SiC fibers were prepared from the same precursor and process but with different heat treatment temperatures. The one prepared at a higher temperature(No.1) had a higher crystallinity than the another one(No.2). A thin pyrolytic carbon(PyC) interlayer was coated on the preforms by a methane CVD method before impregnation. Their microstructures and mechanical properties were investigated by TEM, SEM, Raman spectroscopy and mechanical tests. Results showed that both had a polycrystalline structure with grain sizes of 8-15 nm. Fiber pullout was seen from the fracture cross-section of the composites after a bending test, indicating pseudo-ductile fracture behavior. The composite using No.1 SiC fibers had an average flexural strength, elastic modulus and fracture toughness of 955.0±42.8 MPa, 110.3±1.7 GPa and 28.5±2.8 MPa·m~(1/2), respectively, which are superior to those of the material formed using No.2 SiC fibers. This was ascribed to the high modulus and excellent thermal resistance of the stoichiometric No.1 SiC fibers. The PyC layer adhering to No.1 SiC fibers was ordered and smooth while that deposited on No.2 SiC fibers had a loose and granular microstructure, which was attributed to the different surface chemistries of the two types of SiC fibers.
Three-dimensional(3 D) SiC/SiCf composites were fabricated by a polymer impregnation and pyrolysis(PIP) method using 3 D four directional braided preforms from two kinds of SiC fibers as the reinforcements and liquid polycarbosilane as the SiC precursor. Both kinds of SiC fibers were prepared from the same precursor and process but with different heat treatment temperatures. The one prepared at a higher temperature(No.1) had a higher crystallinity than the another one(No.2). A thin pyrolytic carbon(PyC) interlayer was coated on the preforms by a methane CVD method before impregnation. Their microstructures and mechanical properties were investigated by TEM, SEM, Raman spectroscopy and mechanical tests. Results showed that both had a polycrystalline structure with grain sizes of 8-15 nm. Fiber pullout was seen from the fracture cross-section of the composites after a bending test, indicating pseudo-ductile fracture behavior. The composite using No.1 SiC fibers had an average flexural strength, elastic modulus and fracture toughness of 955.0±42.8 MPa, 110.3±1.7 GPa and 28.5±2.8 MPa·m~(1/2), respectively, which are superior to those of the material formed using No.2 SiC fibers. This was ascribed to the high modulus and excellent thermal resistance of the stoichiometric No.1 SiC fibers. The PyC layer adhering to No.1 SiC fibers was ordered and smooth while that deposited on No.2 SiC fibers had a loose and granular microstructure, which was attributed to the different surface chemistries of the two types of SiC fibers.
引文
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[19] Shi Y M ,Luo F,Ding D H.Effects of thermal oxidation on microwave-absorbing and mechanical properties of SiCf/SiC composites with PyC interphas[J].Transactions of Nonferrous Metals Society of China,2015,25:1484-1489.
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[21] Hu Y,Luo F,Duan S C.Mechanical and dielectric properties of SiCf/SiC composites fabricated by PIP combined with CIP process[J].Ceramics International,2016,42:6800-6806.
[22] Zhao S,Yang Z C,Zhou X G.Microstructure and mechanical properties of compact SiC/SiC composite fabricated with an infiltrative liquid precursor[J].Journal of American Ceramic Society,2015,98(4):1332-1337.
[23] Shimoo T,Tsukada I,Seguchi T.Effect of firing temperature on the thermal stability of low-oxygen silicon carbide fibers[J].Journal of American Ceramic Society,1998,81(8):2109-2115.
[24] Takeda M,Imai Y,Ichikawa H.Thermal stability of SiC fiber prepared by an irradiation-curing process[J].Composites Science and Technology,1999,59:793-799.
[25] Pauw V D,Hawecker J,Schneider R.Dependence of pyrocarbon microstructure on the substrate and annealing during the initial stage of chemical vapor deposition[J].Carbon,2008,46:236-244.
[26] Bertrand S,Pailler R,Lamon J.Influence of strong fiber/coating interlayers on the mechanical behavior and lifetime of hi-nicalon/(PyC/SiC)n/SiC minicomposites[J].Journal of American Ceramic Society,2001,84:787-94.
[2] Katoh Y,Snead L L,Henager Jr C H.Current status and recent research achievements in SiC/SiC composites[J].Journal of Nuclear Materials,2014,455:387-397.
[3] Snead L L,Nozawa T,Ferraris M.Silicon carbide composites as fusion power reactor structural materials[J].Journal of Nuclear Materials,2011,417:330-339.
[4] Nozawa T,Hinoki T,Hasegawa A.Recent advances and issues in development of silicon carbide composites for fusion applications[J].Journal of Nuclear Materials,2009,386-388:622-627.
[5] Zhou X G,Wang H L,Zhao S.Progress of SiCf/SiC composites for nuclear application[J].Advanced Ceramics,2016,37(3):151-167.
[6] Bunsell A R,Piant A.A review of the development of three generations of small diameter silicon carbide fibres[J].Journal of Materials Science,2006,41:823-839.
[7] Takeda M,Sakamoto J,Imai Y.Thermal stability of the low-oxygen-content silicon carbide fiber,Hi-NicalonTM[J].Composites Science and Technology,1999,59:813-819.
[8] Katoh Y,Ozawa K,Shih C.Continuous SiC fiber,CVI SiC matrix composites for nuclear applications:Properties and irradiation effects[J].Journal of Nuclear Materials,2014,448:448-476.
[9] Ortona A,Fend T,Yu H W.Fabrication of cylindrical SiCf/Si/SiC-based composite by electrophoretic deposition and liquid silicon infiltration[J].Journal of the European Ceramic Society,2014,34:1131-1138.
[10] Yoshida K,Akimoto H,Yano T.Mechanical properties of unidirectional and crossply SiCf/SiC composites using SiC fibers with carbon interphase formed by electrophoretic deposition process[J].Progress in Nuclear Energy 2015,82:148-152.
[11] Buet E,Sauder C,Sornin D.Influence of surface fiber properties and textural organization of a pyrocarbon interphase on the interfacial shear stress of SiC/SiC minicomposites reinforced with Hi-Nicalon S and Tyranno SA3 fibres[J].Journal of the European Ceramic Society,2014,34:179-188.
[12] Blagoeva D T,J Hegeman J B,Jong M.Characterisation of 2D and 3D Tyranno SA3 CVI SiCf/SiC composites[J].Materials Science and Engineering A,2015,638:305-313.
[13] Shimoda K,Hinoki T,Kohyama A.Effect of additive content on transient liquid phase sintering in SiC nanopowder infiltrated SiCf/SiC composites[J].Composites Science and Technology,2011,71:609-615.
[14] Morscher G N,John R,Zawada L.Creep in vacuum of woven Sylramic-iBN melt-infiltrated composites[J].Composites Science and Technology,2011,71:52-59.
[15] Liu H T,Cheng H F,Wang J.Microstructural investigations of the pyrocarbon interphase in SiC fiber-reinforced SiC matrix composites[J].Materials Letters,2009,63 (23):2029-2031.
[16] Chai Y X,Zhou X G,Zhang H Y.Effect of oxidation treatment on KD-II SiC fiber-reinforced SiC composites[J].Ceramics International,2017,43:9934-9940.
[17] Luo Z,Cao H,Ren H.Tension-tension fatigue behavior of a PIP SiC/SiC composite at elevated temperature in air[J].Ceramics International,2016,42:3250-3260.
[18] Wang H L,Zhou X G,Yu J S.Fabrication of SiCf/SiC composites by chemical vapor infiltration and vapor silicon infiltration[J].Materials Letters,2010,64:1691-1693.
[19] Shi Y M ,Luo F,Ding D H.Effects of thermal oxidation on microwave-absorbing and mechanical properties of SiCf/SiC composites with PyC interphas[J].Transactions of Nonferrous Metals Society of China,2015,25:1484-1489.
[20] Luo Z,Zhou X G,Yu J S.High-performance 3D SiC/PyC/SiC composites fabricated by an optimized PIP process with a new precursor and a thermal molding method[J].Ceramics International,2014,40:6525-6532.
[21] Hu Y,Luo F,Duan S C.Mechanical and dielectric properties of SiCf/SiC composites fabricated by PIP combined with CIP process[J].Ceramics International,2016,42:6800-6806.
[22] Zhao S,Yang Z C,Zhou X G.Microstructure and mechanical properties of compact SiC/SiC composite fabricated with an infiltrative liquid precursor[J].Journal of American Ceramic Society,2015,98(4):1332-1337.
[23] Shimoo T,Tsukada I,Seguchi T.Effect of firing temperature on the thermal stability of low-oxygen silicon carbide fibers[J].Journal of American Ceramic Society,1998,81(8):2109-2115.
[24] Takeda M,Imai Y,Ichikawa H.Thermal stability of SiC fiber prepared by an irradiation-curing process[J].Composites Science and Technology,1999,59:793-799.
[25] Pauw V D,Hawecker J,Schneider R.Dependence of pyrocarbon microstructure on the substrate and annealing during the initial stage of chemical vapor deposition[J].Carbon,2008,46:236-244.
[26] Bertrand S,Pailler R,Lamon J.Influence of strong fiber/coating interlayers on the mechanical behavior and lifetime of hi-nicalon/(PyC/SiC)n/SiC minicomposites[J].Journal of American Ceramic Society,2001,84:787-94.