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1.
Electromagnetic shielding properties of carbon‐rich chemical vapor infiltration‐prone silicon carbide matrix composites
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Daoyang Han Hui Mei Shanshan Xiao Laifei Cheng 《Journal of the American Ceramic Society》2018,101(5):1991-1998
This study focuses on the electromagnetic interference shielding effectiveness (EMI SE) of SiC nanowire/SiC ceramic composites (SiCnw/SiC) manufactured by chemical vapor infiltration of SiCnw aerogels with carbon‐rich SiC. The total EMI SE of a 1.0 mm thick ceramic composite specimen with density of only 2.68 g/cm3, was found to be 43‐44 dB, which indicates an excellent EM shielding capability of the ceramic composite corresponding to blocking of 99.99% of the incident EM signal. It was found that the carbon‐rich CVI‐SiC matrix possess excellent EM shielding properties, therefore, the CVI‐SiC CMCs themselves possess an excellent EM shielding property as a result of the carbon‐rich SiC matrix. 相似文献
2.
The BN interphase of SiC fiber-reinforced SiC matrix (SiCf/SiC) composites was fabricated by dip-coating process with boric acid and urea as precursor. The results show that the tensile strength of SiC fiber decreases about 30% after BN coating treatment, but the BN coating has little influence on the electrical resistivity of SiC fiber. Compared with the as-received SiCf/SiC composites, the SiCf/SiC composites with BN interphase exhibit a toughened fracture behavior, and the flexural strength is about 2 times that of the as-received SiCf/SiC composites. From the microstructural analysis, it can be confirmed that the BN interphase plays a key part in weakening interfacial bonding, which can improve the mechanical properties of SiCf/SiC composites remarkably. Owing to the close dielectric properties between SiC and BN, the complex permittivity of SiCf/SiC composites with and without the BN interphase is similar. 相似文献
3.
《Ceramics International》2015,41(8):9957-9965
A single-layer radar-absorbing structure in the X-band (8.2 GHz to 12.4 GHz) was designed and fabricated by blending multi-walled carbon nanotubes (MWCNTs) with the binder matrix of SiC fiber/aluminum phosphate matrix (SiCf/AlPO4) composite. The SiC interphase was successfully prepared on SiC fibers by a precursor infiltration and pyrolysis (PIP) method. The morphology of as-received interphase was observed by SEM, and its structure was characterized by XRD and Raman spectrum. The effects of PIP–SiC interphase on the mechanical and dielectric properties of the composite were investigated. The influence of MWCNTs content on the dielectric and microwave-absorption properties of coated SiCf/AlPO4 composite was discussed. When the content of MWCNTs was between 1.5 wt% and 3.5 wt% and the composite thickness is in the range of 2.5–3.5 mm, the SiCf/AlPO4 composite achieved excellent absorbing wave property in X-band. 相似文献
4.
采用低压化学气相渗透法制备了具有和不具有热解炭界面层的2.5维连续SiC纤维增强的SiC复合材料(SiCf/SiC).SiC纤维的体积分数为30%和41%.所制备复合材料的气孔率为20%左右.当纤维为30%时,沉积有0.1 μm热解炭界面层的复合材料的弯曲强度由未加热解炭界面层的232MPa增加到328MPa,而且材料由灾难性断裂转变为非灾难性断裂.在同一制备条件下,纤维体积分数为41%的SiCf/SiC比30%的SiCf/SiC具有更高的气孔率.纤维为41%时,热解炭界面层厚度为0.1 μm的SiCf/SiC的弯曲强度只有244MPa,但是它具有更高的韧性和更长的纤维拔出长度. 相似文献
5.
《Ceramics International》2020,46(3):2693-2702
To improve densification degree and reduce process time, microwave sintering and heat molding method were combined to prepared SiC matrix reinforced SiC (SiC/SiC) composite via polymer infiltration and pyrolysis process (PIP). The effects of heat molding pressures on the densification process, flexural behaviors and failure modes of the fabricated SiC/SiC were examined via scanning electron microscopy (SEM), computed tomography (CT) technique and mercury intrusion test. Results indicate that heat molding process promoted the densification degrees of SiC/SiC and adjusted the interphase bonding between SiC matrix and SiC fibers on the basis of rapid microwave heating. Owing to the appropriate interphase bonding, SiC/SiC composites fabricated under the heat molding pressure of 3 MPa had preferable flexural properties and failure mode. 相似文献
6.
Owing to the degradation of the mechanical properties of the SiC fiber reinforced SiC matrix (SiCf/SiC) composites with the pyrocarbon (PyC) and BN interphases under oxidation environment and neutron irradiation, single layer SiC interphases prepared by chemical vapor deposition (CVD) process were employed to substitute for them. Effects of the CVD SiC interphases on the mechanical properties and interfacial characteristics of the SiCf/SiC composites fabricated by precursor infiltration and pyrolysis (PIP) process were investigated. Compared with the as-received SiCf/SiC composites, the SiCf/SiC composites with the single layer CVD SiC interphases exhibit an obvious toughened fracture behavior, the flexural strength of which is about 4 times that of the as-received SiCf/SiC composites. From the microstructural analysis, it can be confirmed that the SiC interphases play a key part in protecting the fibers from damage during composite preparation and weakening interfacial bonding, which can provide high in situ fiber strength and appropriate interfacial bonding strength for the SiCf/SiC composites. 相似文献
7.
T. Ganesh Babu Renjith Devasia 《Journal of Inorganic and Organometallic Polymers and Materials》2016,26(4):764-772
Ceramic matrix composites (CMCs) are potential thermo-structural materials for use in space applications. Fiber/matrix (F/M) interface plays a key role in determining the mechanical properties of CMCs. Present study focuses on the optimization of F/M volume ratio and the influence of Pyrocarbon (PyC) interphase coating on the mechanical properties of CMCs derived from precursor route. CMCs are fabricated using phenol formaldehyde (PF) resin and boron modified PF (BPF) resin as precursor slurries, 2D carbon fabric (Toray, T300 3K, 8H, satin weave) as reinforcement and PyC as interphase. The deposition of PyC interphase was done by chemical vapor infiltration on the carbon fabric followed by densification of the matrix using reaction bonded silicon carbide method. In CMCs prepared from PF resin, without interphase the flexural strength improves from 25 ± 3.9 MPa (fiber content-40) to 63 ± 9.9 MPa (fiber content-60) on increasing the fiber vol%. In the second part of the investigation, the effect of PyC interphase was studied using CMCs prepared from BPF resin with fiber volume ratio of 60 %. The CMCs with PyC interphase shows an improvement in flexural strength (102 ± 11.5 MPa) compared to that of CMCs prepared without interphase (38 ± 4.4 MPa). The fractography of CMCs with and without interphase was closely evaluated under a scanning electron microscope. CMCs without interphase show no fiber pull-out, indicating the strong fiber-matrix bonding. While CMCs with interphase show fiber pull-out phenomenon and hence fails in a ductile manner. 相似文献
8.
Interphase degradation of three‐dimensional Cf/SiC–ZrC–ZrB2 composites fabricated via reactive melt infiltration
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Xiaowu Chen Qian Feng Le Gao Xiangyu Zhang Shaoming Dong Jingxiao Wang Qiang Zhong Yanmei Kan Dewei Ni 《Journal of the American Ceramic Society》2017,100(10):4816-4826
Layer‐structured interphase, existing between carbon fiber and ultrahigh‐temperature ceramics (UHTCs) matrix, is an indispensable component for carbon fiber reinforced UHTCs matrix composites (Cf/UHTCs). For Cf/UHTCs fabricated by reactive melt infiltration (RMI), the interphase inevitably suffers degradation due to the interaction with the reactive melt. Here, Cf/SiC–ZrC–ZrB2 composite was fabricated by reactive infiltration of ZrSi2 melt into sol‐gel prepared Cf/B4C–C preform. (PyC–SiC)2 interphase was deposited on the fiber to investigate the degradation mechanism under ZrSi2 melt. It was revealed that the degraded interphase exhibited typical features of Zr aggregation and SiC residuals. Moreover, the Zr species diffused across the interphase and formed nanosized ZrC phase inside the fiber. A hybrid mechanisms of chemical reaction and physical melting were proposed to reveal the degradation mechanism according to characterization results and heat conduction calculations. Based on the degradation mechanism, a potential solution to mitigate interphase degradation is also put forward. 相似文献
9.
《Ceramics International》2020,46(4):4493-4501
The carbon fiber/pyrolytic carbon/silicon carbide (Cf/SiC) composite was prepared by precursor infiltration and pyrolysis (PIP), and the link between antifriction effect and microstructure evolution of the composite by increasing heat treatment temperature was studied by a reciprocating pin-on-disk configuration under dry sliding condition. The results indicate that the changing structure of fiber-matrix interface and SiC matrix of the composite by increasing heat treated temperature could influence the carbon content of friction surface, resulting an obvious difference in tribological property. The friction coefficient is reduced 24.3%, 26.8%, 33.9% at different test frequencies after 1800 °C heat treatment without aggravating wear. The finding paves us an effective way to modify the tribological property of Cf/SiC composite (PIP). 相似文献
10.
《Journal of the European Ceramic Society》2023,43(5):1828-1842
Interphase plays an important role in the mechanical behavior of SiC/SiC ceramic-matrix composites (CMCs). In this paper, the microstructure and tensile behavior of multilayered (BN/SiC)n coated SiC fiber and SiC/SiC minicomposites were investigated. The surface roughness of the original SiC fiber and SiC fiber deposited with multilayered (BN/SiC), (BN/SiC)2, and (BN/SiC)4 (BN/SiC)8 interphase was analyzed through the scanning electronic microscope (SEM) and atomic force microscope (AFM) and X-ray diffraction (XRD) analysis. Monotonic tensile experiments were conducted for original SiC fiber, SiC fiber with different multilayered (BN/SiC)n interfaces, and SiC/SiC minicomposites. Considering multiple damage mechanisms, e.g., matrix cracking, interface debonding, and fibers failure, a damage-based micromechanical constitutive model was developed to predict the tensile stress-strain response curves. Multiple damage parameters (e.g., matrix cracking stress, saturation matrix crack stress, tensile strength and failure strain, and composite’s tangent modulus) were used to characterize the tensile damage behavior in SiC/SiC minicomposites. Effects of multilayered interphase on the interface shear stress, fiber characteristic strength, tensile damage and fracture behavior, and strength distribution in SiC/SiC minicomposites were analyzed. The deposited multilayered (BN/SiC)n interphase protected the SiC fiber and increased the interface shear stress, fiber characteristic strength, leading to the higher matrix cracking stress, saturation matrix cracking stress, tensile strength and fracture strain. 相似文献
11.
短切SiC纤维含量对SiCsf/LAS复合材料性能的影响 总被引:1,自引:0,他引:1
用热压烧结法制备了不同纤维含量的SiCsf/LAS玻璃陶瓷复合材料,研究了该复合材料的微观结构、力学性能和微波介电性能。结果表明:随着SiC纤维含量的增加,SiCsf/LAS材料的抗弯强度先增加后降低,最大值为104MPa。由于碳界面层的形成,SiCsf/LAS比LAS具有更高的介电常数。当SiC短切纤维的质量分数为1.5%时,SiCsf/LAS复合材料介电常数具有最大值,其实部ε′和虚部ε″均值分别为48和66,并具有明显的频散效应。 相似文献
12.
《Ceramics International》2017,43(12):8922-8931
The tensile strength and microwave absorbing properties of the amorphous silicon carbide fiber (Tyranno-ZMI) annealed at different temperatures were studied. The tensile strength of the as-received ZMI fiber tows was 1.1 GPa; and the average real and imaginary parts of permittivities of the as-received ZMI/resin samples were 11.3 and 10.5 respectively. The major dielectric loss mechanism of the fibers was conduction loss, which was due to high electrical conductivity of the enriched carbon in ZMI fibers. The 2.0 mm thick ZMI/resin composites could absorb 80% microwave energy in X band, indicating good microwave absorbing property. After heat treatment, fibers degraded gradually and permittivities increased, which were mainly attributed to the decomposition of amorphous SiCxOy and the growth of the SiC nanocrystals and free carbon nanodomains. 相似文献
13.
采用化学气相沉积法制备了微螺旋炭纤维(CMCs),研究了其在频率为8.2 ̄12.4GHz范围内的微波介电特性;以环氧树脂为胶粘剂制备了CMCs/环氧复合吸波涂层,并对其吸波性能进行了研究。结果表明,随着CMCs含量的增加,复介电参数实部ε′、虚部ε″和介电损耗tanδ均有所增加,当CMCs含量为1% ̄5%时,ε″和tanδ增幅很小;当CMCs含量为10%时,两者增幅显著增大。ε′表现出高频减小的趋势,同时tanδ表现出高频增大的趋势,这些均有利于实现高频吸波。磁损耗tanξ较小且CMCs含量对其影响不明显。CMCs/环氧复合吸波涂层的反射率随着CMCs含量的增加而明显减小,表现出高频衰减略有增加的趋势,同时出现多吸收峰,这有利于实现宽频吸波。 相似文献
14.
Non-oxide fiber tow reinforced silicon nitride matrix composite was fabricated by low temperature CVI process with PyC as interphase. The tensile strength of the C and SiC fiber tow composites were 547 MPa and 740 MPa, respectively. The difference in tensile strength was analyzed based on the length, amount of pull-out fiber and also interface bonding. The infiltration uniformity of CVI silicon nitride (SiN) matrix within SiC fiber tow was comparable with that of CVI SiC matrix. These results suggested that the low temperature CVI process is suitable for the fabrication of fiber reinforced SiN matrix composites with proper interface bonding and high strength. 相似文献
15.
《Journal of the European Ceramic Society》2023,43(4):1397-1406
Unidirectional SiCf/SiC composites (UD SiCf/SiC composites) with excellent mechanical properties were successfully fabricated by a modified PIP method which involved the preparation of film-like matrix containing carbon layer with a low concentration PCS solution followed by the rapid densification of composites with a high concentration PCS solution. Carbon layers were in-situ formed and alternating with SiC layers in the as-received matrix. The unique microstructure endows the composites with appropriate interfacial bonding state, good load transfer ability of interphase and matrix and load bearing ability of fiber, and great crack deflection capacity, which ensures the synergy of high strength and toughness of composites. It is also found that the fiber volume fraction in the preform makes a non-negligible effect on the distribution of interphase and matrix, of which the reasonable adjustment can be utilized to optimize the mechanical properties of composites. Compared with the composites only using high concentration PCS solution, the UD SiCf/SiC composites prepared by the modified PIP method exhibit superior mechanical properties. Ultrahigh flexural strength of 1318.5 ± 158.3 MPa and fracture toughness of 47.6 ± 5.6 MPa·m1/2 were achieved at the fiber volume fraction of 30%. 相似文献
16.
Takaaki Koyanagi Takashi Nozawa Yutai Katoh Lance L. Snead 《Journal of the European Ceramic Society》2018,38(4):1087-1094
For the development of silicon carbide (SiC) materials for next-generation nuclear structural applications, degradation of material properties under intense neutron irradiation is a critical feasibility issue. This study evaluated the mechanical properties and microstructure of a chemical vapor infiltrated SiC matrix composite, reinforced with a multi-layer SiC/pyrolytic carbon–coated Hi-NicalonTM Type S SiC fiber, following neutron irradiation at 319 and 629?°C to ~100 displacements per atom. Both the proportional limit stress and ultimate flexural strength were significantly degraded as a result of irradiation at both temperatures. After irradiation at 319?°C, the quasi-ductile fracture behavior of the nonirradiated composite became brittle, a result that was explained by a loss of functionality of the fiber/matrix interface associated with the disappearance of the interphase due to irradiation. The specimens irradiated at 629?°C showed increased apparent failure strain because the fiber/matrix interphase was weakened by irradiation-induced partial debonding. 相似文献
17.
《Journal of the European Ceramic Society》2023,43(10):4336-4348
Toughness enhancement in ceramic matrix composites (CMCs) with brittle matrix and fiber phases is often accomplished by introducing a weak finite-thickness interphase between the fiber and matrix. The current work presents a progressive damage model to predict the tensile response of single tow CMCs (mini-composite) representative of a unidirectional composite at the microscale. Implementation of a 3-phase shear-lag model for a geometrically accurate representation of the underlying microstructure in CMCs with finite thickness interphase has been highlighted. A probabilistic progressive modeling approach has been adopted, accounting for multiple matrix cracking, interfacial debonding, and fiber failure in 3-phase mini-composites. The predicted tensile response of CMCs from the progressive damage modeling approach agrees with experimental results obtained for C/BN/SiC mini-composites validating the approach. 相似文献
18.
Gregory N. Morscher † Hee Mann Yun † James A. DiCarlo Linus Thomas-Ogbuji † 《Journal of the American Ceramic Society》2004,87(1):104-112
Typically, the debonding and sliding interface enabling fiber pullout for SiC-fiber-reinforced SiC-matrix composites with BN-based interphases occurs between the fiber and the interphase. Recently, composites have been fabricated where interface debonding and sliding occur between the BN interphase and the matrix. This results in two major improvements in mechanical properties. First, significantly higher failure strains were attained due to the lower interfacial shear strength with no loss in ultimate strength properties of the composites. Second, significantly longer stress-rupture times at higher stresses were observed in air at 815°3C. In addition, no loss in mechanical properties was observed for composites that did not possess a thin carbon layer between the fiber and the interphase when subjected to burner-rig exposure. Two primary factors were hypothesized for the occurrence of debonding and sliding between the BN interphase and the SiC matrix: a weaker interface at the BN/matrix interface than the fiber/BN interface and a residual tensile/shear stress-state at the BN/matrix interface of melt-infiltrated composites. Also, the occurrence of outside debonding was believed to occur during composite fabrication, i.e., on cooldown after molten silicon infiltration. 相似文献
19.
《Ceramics International》2022,48(14):20168-20175
To improve the electromagnetic (EM) wave absorption performance of rare earth silicate in harsh environments, this work synthesized dense SiC–Y2Si2O7 composite ceramics with excellent EM wave absorption properties by using the polymer permeation pyrolysis (PIP) process, which introduced carbon and SiC into a porous Y2Si2O7 matrix to form novel composite ceramics. SiC–Y2Si2O7 composite ceramics with different numbers of PIP cycles were tested and analysed. The results show that the as-prepared composites exhibit different microstructures, porosities, dielectric properties and EM wave absorption properties. On the whole, the SiC–Y2Si2O7 composite ceramics (with a SiC/C content of 29.88 wt%) show superior microwave absorption properties. The minimum reflection loss (RLmin) reaches ?16.1 dB when the thickness is 3.9 mm at 9.8 GHz. Moreover, the effective absorption bandwidth (EAB) included a broad frequency from 8.2 GHz to 12.4 GHz as the absorbent thickness varied from 3.15 mm to 4.6 mm. In addition, the EM wave absorption mechanism was analysed profoundly, which ascribed to the multiple mediums of nanocrystalline, amorphous phases and turbostratic carbon distributed in the Y2Si2O7 matrix. Therefore, SiC–Y2Si2O7 composite ceramics with high-efficiency EM wave absorption performance promise to be a novel wave absorbing material for applications in harsh environments. 相似文献
20.
《Journal of the European Ceramic Society》2017,37(3):883-890
Novel Nextel™ 440 aluminosilicate fiber reinforced SiC matrix composites, with/without chemical vapor deposited carbon interphase were fabricated by polymer derived ceramic process, and they were studied by a combination of micro- and macro- mechanical techniques such as nanoindentation, micropillar splitting, fiber push-in, digital image correction and high temperature three point bend tests. Specifically, micropillar splitting test was firstly employed to measure in-situ the localized fracture toughness. The results revealed that the carbon interphase can effectively hinder the interfacial reactions between Nextel™ 440 fiber and SiC matrix, thus remarkably weakening the composite interfacial shear strength from ∼293 MPa to ∼42 MPa, and enhance the composite fracture toughness from ∼1.8 MPa√m to ∼6.3 MPa√m, respectively. This is mainly a consequence of weak interface that triggers crack deflection at the fiber/interphase interface. Finally, this novel composite showed stable mechanical properties in vacuum at temperature range from 25 °C to 1000 °C. 相似文献