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1.
《Ceramics International》2022,48(7):9157-9163
Herein, the SiC ceramic aerogels with in-situ growth of SiC nanowires (SiCw/SiC CAs) have been synthesized by polymer‐derived ceramics (PDCs) method. The morphology, microstructure, and phase composition of the as-prepared samples were systematically investigated through SEM, XRD, TEM, Raman spectrum, FT-IR spectrum, and XPS spectrum techniques. The results showed that the as-obtained SiCw has a diameter of about 80 nm and a length of 1–3.5 μm. In addition, the formation mechanism and evolution process of growth SiCw were systematically studied using a VLS growth mechanisms. The way in this work could be expanded to synthesize other Si-based porous ceramic aerogel nanostructed with nanowires. 相似文献
2.
Lei Su Baoyu Li Hongjie Wang Min Niu Xingyu Fan 《Journal of the American Ceramic Society》2020,103(5):3321-3329
Carbon-bonded carbon fiber (CBCF) composites are promising lightweight and high efficient thermal insulators to be applied in aerospace area, but their practical applications are usually restricted by the low mechanical performance and poor oxidation resistance. To overcome these drawbacks, many efforts have been made in the fabrication of ceramic coated CBCF composites. However, the densities of these modified composites are usually very high, which would result in the reduction in their thermal insulation performance. Herein, we prepared a CBCF composite with SiC nanowires enhanced interfibrous junctions and SiOC ceramic coated carbon fibers (SiCNWs-SiOC-CBCF). Similar to CBCF, the SiCNWs-SiOC-CBCF exhibits a low density of 0.35 g/cm3 and an anisotropic and highly porous architecture. The SiCNWs-SiOC-CBCF possesses a compressive strength of 3.8 MPa and a compression modulus of 195.7 MPa in the X (or Y) direction, ~26.7% and 150% higher than those of CBCF respectively. It can also suffer from an isothermal treatment in air at 900°C for 120 minutes. The combination of these properties makes the SiCNWs-SiOC-CBCF a good candidate for thermal insulator to be applied in extreme conditions. 相似文献
3.
Junjie Qian Anze Shui Chao He Xuan Wang Mei Cai Yadi Pu Ping Hu Bin Du 《Ceramics International》2021,47(6):8004-8013
Herein, the SiC nanowires were successfully fabricated via chemical vapor infiltration (CVI) into carbon fiber felts (CFs) and then the SiOC/SiCnws/CFs composites were synthesized by precursor infiltration and pyrolysis (PIP) processes. Results indicated that the lightweight composites possessed enhanced mechanical performance, low thermal conductivity, and excellent electromagnetic wave absorption properties. Detailedly, the compressive strength reached to 22.0 MPa and 9.6 MPa after two PIP processes cycles in z and x/y directions, respectively. Meanwhile, the composites exhibited tailored electromagnetic wave absorption performance with the effective absorption bandwidth of 3.06 GHz, and the minimum reflection loss (RLmin) was -48.2 dB with a thickness of 3.6 mm. The present work has a guidance to prepare and design multifunction properties for application in harsh environment. 相似文献
4.
《Journal of the European Ceramic Society》2019,39(15):4625-4633
To improve the mechanical properties of carbon fibers/lithium aluminosilicate (Cf/LAS) composites, Cf/LAS with in-situ grown SiC nanowires (SiCnw-Cf/LAS) were prepared by chemical vapor phase reaction, precursor impregnation, and hot press sintering, consecutively. The effect of multi-scaled reinforcements (micro-scaled Cf and nano-scaled SiCnw) on the mechanical properties was investigated. The phase composition, microstructure and fracture surface of the composites were characterized by XRD, Raman Spectrum, SEM, and TEM. The morphology of SiCnw has a close relation with the content of Si. Microstructure analysis suggests that the growth of SiC nanowires depends on the VLS mechanism. The multi-scale reinforcement formed by Cf and SiCnw can significantly improve the mechanical properties of Cf/LAS. The bending strength of SiCnw-Cf/LAS reaches to 597 MPa, achieving an increase of 19% to Cf/LAS. Moreover, the samples show a maximum fracture toughness of 11.01 MPa m1/2, achieving an increase of 46.4% to Cf/LAS. Through analysis of the fracture surface, the improved mechanical properties could be attributed to the multi-scaled reinforcements by the pull-out and debonding of Cf and SiCnw from the composites. 相似文献
5.
短碳纤维增强碳化硅基复合材料的制备 总被引:5,自引:0,他引:5
短纤维的分散均匀性一直是短纤维复合材料应用受限的主要原因.采用固相球磨分散和熔融渗硅工艺,可得到均匀分散的短碳纤维增强碳化硅基复合材料.并利用金相显微镜见察复合材料微观形貌,测试复合材料的抗弯强度和断后韧性. 相似文献
6.
《Ceramics International》2016,42(9):10614-10618
SiOC modified carbon-bonded carbon fiber composites (CBCFs) with densities of 0.38, 0.61, 0.94 g cm−3 were prepared by precursor infiltration and pyrolysis method using dimethoxydimethylsilane and methyltrimethoxysilane as precursors. The densification behavior was investigated by analyzing the microstructure of CBCF-SiOC (CS) composites with different densities. The mechanical properties and oxidation resistance of the CS composites were studied. Results indicate that the CS composites with the density of 0.94 g cm−3 exhibit better mechanical and anti-oxidation properties. 相似文献
7.
《Journal of the European Ceramic Society》2022,42(10):4154-4161
Silicon-carbide nanowires (SiCnws) have been considered as dielectric loss materials for application in the field of electromagnetic wave (EMW) attenuation. In this study, SiCnws/carbon fiber (CF) composites were fabricated using precursor infiltration and pyrolysis process for the in-situ growth of SiCnws. The SiCnw fraction of the SiCnws/CF composites could be adjusted using various catalysts. At a small SiCnw fraction (38 wt%), the composites exhibited excellent EMW absorption performance with the minimum reflection loss of ? 18.3 dB when their thickness was only 1.2 mm and can cover the entire X and Ku bands by adjusting the material thickness. They transformed from EMW absorption performance to electromagnetic interference (EMI) shielding property with the increase in SiCnw fraction from 38 wt% to 73 wt%, reaching an EMI shielding effectiveness of 31.25 dB. In addition, the density of the SiCnws/CF composites was only 0.31–0.41 g/cm3, and their compressive strength can reach 0.61–0.99 MPa with excellent high-temperature stability. Therefore, the SiCnws/CF composite presents a promising EMW absorption and EMI shielding material that can be applied in harsh environments. 相似文献
8.
《Ceramics International》2022,48(2):1778-1788
SiC/Al2O3 composite powders with SiC nanowires were synthesized using a one-step combustion synthesis method taking silica fume (SiO2), aluminum powder (Al) and carbon black (CB) as raw materials, while ferrocene (C10H10Fe) was used as the catalyst. The calculated results for the relationship between the equilibrium phase and temperature of the Al–SiO2–C system show that SiC and Al2O3 are the only equilibrium phases in the system. In addition, the effects of C10H10Fe on the combustion synthesis process and products were studied. It was found that with increasing catalyst content, the amount of residual Si in the products first decreases and then increases, the combustion temperature first increases and then decreases, and the nanowire content continues to increase. For an optimal amount of C10H10Fe of 0.75 wt%, almost no residual Si is observed in the product, while the combustion temperature (Tc) is high (2104 K), the SiC nanowire content is relatively high, and the nanowire aspect ratio is large. In addition, two growth mechanism models for SiC nanowires: VS and VLS were validated. 相似文献
9.
Bin Du Chao He Junjie Qian Xuan Wang Mei Cai Anze Shui 《Journal of the American Ceramic Society》2019,102(12):7543-7552
To enhance the oxidation resistance capability of the carbon-bonded carbon fiber composites (CBCFs), a silicide ultra-thick coating as high as 1.6 mm with gradient structure is designed and fabricated via a multi-step rapid sintering method. Compared with other ceramic layers on carbon fiber-based composites, ultra-thick anti-oxidation layer coated-CBCFs have the lowest thermal conductivity. Additionally, ablation behaviors of the ultra-thick ceramics layer coated-CBCFs under the oxyacetylene torch are also investigated. After being exposed to oxyacetylene torch, the ultra-thick ceramics layer coated-CBCFs possess a linear rate range from 0.6 to 1.2 μm/s, while a mass ablation rate ranges from 4.95 × 10−5 g/m2 s to 1.45 × 10−3 g/m2 s. 相似文献
10.
《Ceramics International》2022,48(24):36238-36248
Cf/SiC composite is an excellent structural and functional material, silicon carbide nanowires (SiCnws) are not only a toughening material but also a great application in the field of microwave absorption. In this study, SiCnws are grown on the surface of carbon fiber (Cf) by polymer impregnation and pyrolysis, and the SiC matrix was prepared by chemical vapor osmosis method. The SiCnws are introduced to enhance the mechanical and microwave absorption properties simultaneously. After 3 impregnations, the flexural strength of the composite was 107.35 ± 10 MPa. When the thickness is 1.86 mm, the minimum reflection loss value is ?41.08 dB, and the effective absorption bandwidth (RL ≤ ?10 dB) is 3.86 GHz. Furthermore, the microwave absorption mechanism of the material is discussed. This work provides a new method to prepare lightweight, stable and high-performance microwave absorption materials, and these materials are expected to be used in high temperature environments. 相似文献
11.
Tianbao Cheng 《Journal of the European Ceramic Society》2021,41(4):2335-2346
Carbon fiber reinforced silicon carbide (C/SiC) composites are enabling materials for components working in ultra-high-temperature extreme environments. However, their mechanical properties reported in the literature are mainly limited to room and moderate temperatures. In this work, an ultra-high-temperature testing method for the mechanical properties of materials in inert atmosphere is presented based on the induction heating technology. The flexural properties of a 2D plain-weave C/SiC are studied up to 2600 °C in inert atmosphere for the first time. The deformation characteristics and failure mechanisms at elevated temperatures are gained. Theoretical models for the high-temperature Young’s modulus and tensile strength of 2D ceramic matrix composites are then developed based on the mechanical mechanisms revealed in the experiments. The factors contributing to the mechanical behaviors of C/SiC at elevated temperatures are thus characterized quantitatively. The results provide significant understanding of the mechanical behaviors of C/SiC under ultra-high-temperature extreme environment conditions. 相似文献
12.
《Ceramics International》2020,46(2):1743-1749
SiOC ceramic modified carbon fiber needled felt preform composites (Cf/SiOC) with densities of 0.4 and 0.7 g/cm3 were prepared by precursor infiltration and pyrolysis (PIP) method using methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) as precursors. The densification behavior was investigated through scanning electron microscopy (SEM) analysis of microstructure of Cf/SiOC composites undergoing different PIP times. The results indicate that with increase of PIP times, a great amount of SiOC ceramic was introduced into the preform, completely covering on the carbon fibers and occupying the open pores. The thermal performance, mechanical properties, and oxidation resistance of the composites were studied via various tests. The results illustrate that after two-time PIP procedure, thermal conductivities of the composites are 0.41–2.54 and 1.28–4.04 W/(m·K) in z direction and x/y plane, respectively, at RT-1500 °C. The compressive strengths of the composite arrive at 2.1 MPa in z direction and 7.8 MPa in x/y plane, which are almost 3.5 times and 6.5 times, respectively, counterparts of the raw preform. The incorporation of SiOC ceramic can remarkably improve anti-oxidation ability of the composites at 600 °C. The oxidation weight loss is merely 2.1 wt% after 60-min oxidation at 600 °C. 相似文献
13.
《Ceramics International》2020,46(7):9303-9310
The employment of coating technique on the silicon carbide fibers plays a pivotal role in preparing SiC fiber-reinforced SiC composites (SiCf/SiC) toward electromagnetic wave absorption applications. In this work, SiC nanowires (SiCNWs) are successfully deposited onto the pyrolytic carbon (PyC) coated SiC fibers by an electrophoretic deposition method, and subsequently densified by chemical vapor infiltration to obtain SiCNWs/PyC-SiCf/SiC composites. The results reveal that the introduction of SiCNWs could markedly enhance the microwave absorption properties of PyC-SiCf/SiC composites. Owing to the increasing of SiCNWs loading, the minimum reflection loss of composites raises up to −58.5 dB in the SiCNWs/PyC-SiCf/SiC composites with an effective absorption bandwidth (reflection loss ≤ −10 dB) of 6.13 GHz. The remarkable enhancement of electromagnetic wave absorption performances is mainly attributed to the improved dielectric loss ability, impedance matching and multiple reflections. This work provides a novel strategy in preparing SiCf/SiC composites with excellent electromagnetic wave absorption properties. 相似文献
14.
Hexagonal-shaped SiC nanowires were in situ formed in C/SiC composites with ferrocene as catalyst in the densification process of polymer impregnation and pyrolysis. The effect of SiC nanowires on microstructure and properties of the composites were studied. The results show that the in situ formed SiC nanowires were hexagonal, mostly with diamer of about 250 nm, and grew by the vapor–liquid–solid (VLS) mechanism. The C/SiC composite with nanowires shows higher bulk density and flexural strength than the one with no SiC nanowires, and the high temperature flexural strength behavior of C/SiC composites with SiC nanowires was evaluated. 相似文献
15.
大丝束碳纤维复合材料力学性能研究 总被引:3,自引:1,他引:2
本文研究了大丝束碳纤维(48K)复合材料的常规力学性能及耐湿热性能,并与小丝束碳纤维(T300.3K)复合材料进行了对比,研究结果可为大丝束复合材料在航空器的次承力件或非承力件的应用提供技术基础。 相似文献
16.
Guang-Yuan Cui Rui-Ying Luo Lian-Yi Wang Peng Huang 《Journal of the European Ceramic Society》2021,41(10):5026-5035
In this study, SiC nanowires (SiCNWS) were grown in situ on the surface of PyC interface through chemical vapor infiltration (CVI) to improve the mechanical characteristics and thermal conductivity of three-dimensional SiCf/SiC composites fabricated via precursor infiltration pyrolysis (PIP). The effect of SiCNWS on the properties of the obtained composites was investigated by comparing them with conventional SiCf/PyC/SiC composites. After the deposition of SiCNWS, the flexural strength of the SiCf/SiC composites was found to increase by 46 %, and the thermal conductivity showed an obvious increase at 25?1000 °C. The energy release of the composites in the damage evolution process was analysed by acoustic emission. The results indicated that the damage evolution process was delayed owing to the decrease in porosity, the crack deflection and bridging of the SiCNWS. Furthermore, the excellent thermal conductivity was attributed to the thermally conductive pathways formed by the SiCNWS in the dense structure. 相似文献
17.
Changcong Wang Kezhi Li Qinchuan He Yangyang Su Caixia Huo Xiaohong Shi 《Ceramics International》2018,44(14):16365-16378
To improve the high-temperature tolerance of carbon/carbon composites, a compact SiC-nanowires toughened LaB6-MoSi2-SiC/SiC (SiCnws-LMS/SiC) coating was designed and fabricated by combination of multiple methods including pack cementation, chemical vapor deposition and supersonic atmospheric plasma spraying. Isothermal oxidation results indicated that the mass loss of LMS/SiC coating decreased from 4.34?±?0.28% to 1.12?±?0.23% after oxidation for 200?h at 1773?K benefit from the addition of SiCnws. Absence of obvious cracks and voids in the coating after oxidation test indicated that the interfaces between various phases and SiCnws could obstruct the crack propagation by releasing the thermal stress in the coating. Meanwhile, after the introduction of SiCnws, the bonding strength and flexural strength of the coating were respectively increased by 54.54% and 59.77% compared to the LMS/SiC coating without SiCnws. The improved mechanical properties could be attributed to the pullout and bridging effects of SiCnws, which created multi-scaled reinforcements, thereby enhancing the load bearing capacity to increase the fracture toughness of the coating. 相似文献
18.
19.
《Ceramics International》2022,48(22):33019-33027
The in-situ SiC whisker and SiC particle composites were prepared by selective laser sintering (SLS) technology, and the longitudinal and transverse growth rates of crystal nuclei at the liquid-solid interface were calculated and analyzed under the traditional vapor-liquid-solid mechanism. A mathematical model of holding time on the number of in-Situ SiC whisker growth was established, and the prediction rate was 95%. The mechanical properties of in-situ SiC whisker and pure SiC samples with similar volume densities were calculated. The results showed that: The longitudinal growth rate of crystal nuclei at the liquid-solid interface was higher than the transverse growth rate. After precursor infiltration pyrolysis (PIP) four-cycle treatment, the fracture toughness per unit volume density of B-1, B-2, and B-3 specimens increased by 198.66%, 225.00%, and 221.05%, respectively, compared with pure SiC specimens, indicating that this method has a vital role in increasing the toughness of SiC ceramics. 相似文献
20.
《Ceramics International》2017,43(2):1722-1730
To protect carbon/carbon composites (C/Cs) against oxidation, SiC coating toughened by SiC nanowires (SiCNWs) and carbon nanotubes (CNTs) hybrid nano-reinforcements was prepared on C/Cs by a two-step technique involving electrophoretic co-deposition and reactive melt infiltration. Co-deposited SiCNWs and CNTs with different shapes including straight-line, fusiform, curved and bamboo dispersed uniformly on the surface of C/Cs forming three-dimensional networks, which efficiently refined the SiC grains and meanwhile suppressed the cracking deflection of the coating during the fabrication process. The presence of SiCNWs and CNTs contributed to the formation of continuous glass layer during oxidation, while toughed the coating by introducing toughing methods such as bridging effect, crack deflection and nanowire pull out. Results showed that after oxidation for 45 h at 1773 K, the weight loss percentage of SiC coated specimen was 1.35%, while the weight gain percentage of the SiCNWs/CNTs reinforced SiC coating was 0.03052% due to the formation of continuous glass layer. After being exposed for 100 h, the weight loss percentage of the SiCNWs/CNTs reinforced SiC coating was 1.08%, which is relatively low. 相似文献