scholarly journals Enhanced mechanical property and tunable dielectric property of SiCf/SiC-SiBCN composites by CVI combined with PIP

2021 ◽  
Author(s):  
Chaokun Song ◽  
Yongsheng Liu ◽  
Fang Ye ◽  
Laifei Cheng ◽  
Pengfei Zhang ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Dielectric Property ◽  
Impedance Matching ◽  
Chemical Vapor ◽  
Functional Materials ◽  
Chemical Vapor Infiltration ◽  
Propagation Path ◽  
Interface Bonding ◽  
Shielding Effectiveness ◽  
Matrix Microstructure

AbstractThe SiBCN matrix via chemical vapor infiltration (CVI) or/and polymer infiltration pyrolysis (PIP) technologies was orderly introduced to SiCf/SiC composites to optimize the mechanical property and electromagnetic (EM) shielding effectiveness simultaneously. The BN interface with the thickness of 350 nm was designed to obtain a little stronger interface bonding. The flexural strength of SiCf/SiC-SiBCN composites reached 545.45±29.59 MPa thanks to the crack deflection between the CVI SiC and CVI SiBCN, as well as CVI SiBCN and PIP SiBCN matrix because of the modulus difference between them. The fracture toughness (KIC) with the value of 16.02±0.94 MPa·m1/2 was obtained owing to the extension of crack propagation path. The adverse effect of stronger interface bonding was eliminated by the design of matrix microstructure for SiCf/SiC-SiBCN composites. The thermal conductivity in the thickness direction was 7.64 W·(m·K)−1 at 1200 °C and the electric resistivity decreased to 1.53×103 Ω·m. The tunable dielectric property was obtained with the coordination of wave-absorption CVI SiBCN matrix and impedance matching PIP SiBCN matrix, and the total shielding effectiveness (SET) attained 30.01 dB. It indicates that the SiCf/SiC-SiBCN composites have great potential to be applied as structural and functional materials.

Microstructure and Mechanical Property of 3D Textile C/SiC Composites Fabricated by Chemical Vapor Infiltration

2006 ◽  
Vol 11-12 ◽  
pp. 81-84 ◽  
Author(s):  
Dong Lin Zhao ◽  
Hong Feng Yin ◽  
Fa Luo ◽  
Wan Cheng Zhou
Keyword(s):  
Mechanical Property ◽  
Silicon Carbide ◽  
Carbon Fiber ◽  
Interfacial Layer ◽  
Chemical Vapor ◽  
Pyrolytic Carbon ◽  
Chemical Vapor Infiltration ◽  
Sic Composites ◽  
Microstructure And Mechanical Property ◽  
Vapor Infiltration

Three dimensional textile carbon fiber reinforced silicon carbide (3D textile C/SiC) composites with pyrolytic carbon interfacial layer were fabricated by chemical vapor infiltration. The microstructure and mechanical property of 3D textile C/SiC composites were investigated. A thin pyrolysis carbon layer (0.2 ± μm) was firstly deposited on the surface of carbon fiber as the interfacial layer with C3H6 at 850°C and 0.1 MPa. Methyltrichlorosilane (CH3SiCl3 or MTS) was used for the deposition of the silicon carbide matrix. The conditions used for SiC deposition were 1100°C, a hydrogen to MTS ratio of 10 and a pressure of 0.1 MPa. The density of the composites was 2.1 g cm-3. The flexural strength of the 3D textile C/SiC composites was 438 MPa. The 3D textile C/SiC composites with pyrolytic carbon interfacial layer exhibit good mechanical properties and a typical failure behavior involving fibers pull-out and brittle fracture of sub-bundle. The real part (ε′) and imaginary part (ε″) of the complex permittivity of the 3D-C/SiC composites are 51.53-52.44 and 41.18-42.08 respectively in the frequency range from 8.2 to 12.4 GHz. The 3D-C/SiC composites would be a good candidate for microwave absorber.

Effects of Carbon Fiber Architecture on the Microstructure and Mechanical Property of C/C-SiC Composites

2010 ◽  
Vol 658 ◽  
pp. 133-136 ◽  
Author(s):  
Ji Ping Wang ◽  
Jian Yong Lou ◽  
Zhuo Xu ◽  
Zhi Hao Jin ◽  
Guan Jun Qiao
Keyword(s):  
Mechanical Property ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Thermal Gradient ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Fiber Architecture ◽  
Carbon Fiber Felt ◽  
Sic Composites ◽  
Microstructure And Mechanical Property

C/C-SiC composites were rapidly fabricated by a two-steps processing. Firstly a short-cut carbon fiber felt (SC) and a 2D carbon fiber felt (2D) were densified to C/C composites by a thermal gradient chemical vapor infiltration (CVI) method with vaporized kerosene as a precursor in 2h, 3h, 4h and 5h, respectively. Then the C/C composites were infiltrated and reacted with melting silicon to obtain C/C-SiC composites. The results show that, with increase of the CVI time, the densities of the two types of C/C-SiC composites decrease in the range of 2.28g/cm3 to 2.00g/cm3; their porosities increase ranging from 1.3% to 7.5%; the contents of the β-SiC and the unreacted Si phases in the composites decline. The flexural strength of the 2D_C/C-SiC composite is much higher than that of the SC_C/C-SiC composite when prepared in the same condition.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

Modeling of Chemical Vapor Infiltration for Pyrocarbon within Capillaries

2016 ◽  
Vol 31 (3) ◽  
pp. 298
Author(s):  
TANG Zhe-Peng ◽  
ZHANG Zhong-Wei ◽  
FANG Jin-Ming ◽  
PENG Yu-Qing ◽  
LI Ai-Jun ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Vapor Infiltration

Microstructures, Strength and Toughness of 2D Cf/(C-SiC) Composites by Chemical Vapor Infiltration

2009 ◽  
Vol 24 (5) ◽  
pp. 939-942 ◽  
Author(s):  
Zhi-Xin MENG ◽  
Lai-Fei CHENG ◽  
Li-Tong ZHANG ◽  
Yong-Dong XU ◽  
Xiu-Feng HAN
Keyword(s):  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Sic Composites ◽  
Strength And Toughness ◽  
Vapor Infiltration

A study on the electromagnetic properties of graphite/bismuth/bismuth oxide-coated composites

2021 ◽  
pp. 004051752199434
Author(s):  
Yuanjun Liu ◽  
Yanfeng Yang
Keyword(s):  
Mechanical Property ◽  
Dielectric Constant ◽  
Bismuth Oxide ◽  
Control Variable ◽  
Single Layer ◽  
Polarization Property ◽  
Electromagnetic Properties ◽  
Shielding Effectiveness ◽  
Absorbing Property ◽  
Layer Coating

Coating is a commonly used process for the preparation of protective textiles. In this study, the absorbing coated composite material was prepared by a coating process, using plain weave polyester/cotton fabric as the base fabric, PU-2540 polyurethane as the binder, and graphite, bismuth and bismuth oxide as the functional particles. The effects of the content of functional particles and the ratio of functional particles on the dielectric constant, reflection loss, shielding effectiveness, and tensile strength of the single-layer coating composites were studied using the control variable method. The results showed that when the frequency was 1–1000 MHz, the real and imaginary parts of the dielectric constant, the tangential value of the loss angle, and the tensile value increased with the increase of the coating content, and the polarization, loss and attenuation property, and mechanical property of the electromagnetic wave were enhanced. When graphite, bismuth, and bismuth oxide was mixed at the ratio of 9:0:0 in weight, the polarization property was the best. When mixed at the ratio of 6:1:2 in weight, the loss performance and attenuation ability were the best. When mixed at the ratio of 6:3:0 in weight, the absorbing property and mechanical property were the best. When mixed at the ratio of 6:2:1 in weight, the shielding property was the best.

scholarly journals Structural Engineering of Hierarchical Aerogels Comprised of Multi-dimensional Gradient Carbon Nanoarchitectures for Highly Efficient Microwave Absorption

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Yongpeng Zhao ◽  
Xueqing Zuo ◽  
Yuan Guo ◽  
Hui Huang ◽  
Hao Zhang ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Structural Engineering ◽  
Carbon Nanomaterials ◽  
Wave Attenuation ◽  
Impedance Matching ◽  
Chemical Vapor ◽  
Electromagnetic Properties ◽  
Effective Bandwidth ◽  
Carbon Aerogels ◽  
Chemical Vapor Deposition Method

AbstractRecently, multilevel structural carbon aerogels are deemed as attractive candidates for microwave absorbing materials. Nevertheless, excessive stack and agglomeration for low-dimension carbon nanomaterials inducing impedance mismatch are significant challenges. Herein, the delicate “3D helix–2D sheet–1D fiber–0D dot” hierarchical aerogels have been successfully synthesized, for the first time, by sequential processes of hydrothermal self-assembly and in-situ chemical vapor deposition method. Particularly, the graphene sheets are uniformly intercalated by 3D helical carbon nanocoils, which give a feasible solution to the mentioned problem and endows the as-obtained aerogel with abundant porous structures and better dielectric properties. Moreover, by adjusting the content of 0D core–shell structured particles and the parameters for growth of the 1D carbon nanofibers, tunable electromagnetic properties and excellent impedance matching are achieved, which plays a vital role in the microwave absorption performance. As expected, the optimized aerogels harvest excellent performance, including broad effective bandwidth and strong reflection loss at low filling ratio and thin thickness. This work gives valuable guidance and inspiration for the design of hierarchical materials comprised of dimensional gradient structures, which holds great application potential for electromagnetic wave attenuation. "Image missing"

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