Mechanical Properties of C/SiC Composites via Precursor Pyrolysis with Pretreated Carbon Fiber

2007 ◽  
Vol 336-338 ◽  
pp. 1245-1247 ◽  
Author(s):  
Song Wang ◽  
Zhao Hui Chen ◽  
Fan Li ◽  
Hai Feng Hu

3D C/SiC composites were fabricated by polycarbosilane (PCS) infiltration and pyrolysis process. The influence of pretreatment of carbon fiber, including pyrolytic carbon coating and thermal treatment, on mechanical properties of C/SiC composites was investigated. The results showed that the composites without fiber pretreatment had a flexural strength of 154MPa and a fracture toughness of 4.8 MPa•m1/2, while those with carbon coating or thermal treatment had much higher strength and toughness, that is, more than 400MPa and 15MPa•m1/2 respectively. Weak interfacial bonding and better in-situ strength of carbon fiber were main reasons for mechanical property improvement with pretreated carbon fiber.

2008 ◽  
Vol 368-372 ◽  
pp. 1019-1021
Author(s):  
Song Wang ◽  
Zhao Hui Chen

C/SiC, C/Si-O-C and C/C composites reinforced with T300 carbon fiber were fabricated via polycarbosilane (PCS), polysiloxane (PSO), and phenolic resin precursor polymers infiltration/pyrolysis, respectively. Flexural strength and fracture toughness of the composites were evaluated. The results showed that all the composites had poor mechanical properties, less than 160 MPa in flexural strength and 5 MPa•m1/2 in fracture toughness. Deep investigation illuminated that the fiber was damaged severely during the preparation of the composites, especially in the first cycle of precursor pyrolysis. Great degradation of the fiber has relationship with coarsening of the microstructure. Bad in-situ strength of the fiber resulted in poor performance of the composites.


2006 ◽  
Vol 11-12 ◽  
pp. 81-84 ◽  
Author(s):  
Dong Lin Zhao ◽  
Hong Feng Yin ◽  
Fa Luo ◽  
Wan Cheng Zhou

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.


2013 ◽  
Vol 544 ◽  
pp. 43-47 ◽  
Author(s):  
Ming Wei Chen ◽  
Hai Peng Qiu ◽  
Jian Jiao ◽  
Xiu Qian Li ◽  
Yu Wang ◽  
...  

SiC fiber reinforced SiC matrix (SiCf-SiC) composites with and without pyrolytic carbon interphase were prepared by polymer impregnation pyrolysis (PIP) progress. The effect of pyrolytic carbon interphase on the fracture behavior and mechanical properties of SiCf/SiC composites was studied. The results show that pyrolytic carbon interphase weakened the bonding between the matrix and the fibers. The mechanical properties of SiCf-SiC composites with carbon coating were improved effectively via fiber debonding and pulling-out from matrix under external loads. The flexural strength and fracture toughness of the above composites reached up to 498.52MPa and 24.09MPa•m1/2, respectively.


2007 ◽  
Vol 336-338 ◽  
pp. 1291-1293
Author(s):  
Xin Gui Zhou ◽  
Chang Cheng Zhou ◽  
Chang Rui Zhang ◽  
Ying Bin Cao ◽  
Shi Qin Zou

3D braided carbon fiber reinforced silicon carbide (3D-Cf/SiC) composites were fabricated by precursor infiltration and pyrolysis(PIP), with carbon coatings prepared by chemical vapor deposition (CVD) before PIP. The effect of 1873K heat treatment on the mechanical properties of Cf/SiC composites were investigated. The results showed that heat treatment before PIP can increase the density of composites and lead to excellent properties of Cf/SiC composites. The flexual strength of the Cf/SiC composites with one cycle of 1873 K heat treatment reached 571 MPa, shear strength 51 MPa, and fracture toughness 18 MPa⋅m1/2.


2008 ◽  
Vol 368-372 ◽  
pp. 1737-1739
Author(s):  
Qiang Qu ◽  
Wen Bo Han ◽  
Song He Meng ◽  
Xing Hong Zhang ◽  
Jie Cai Han

ZrB2-based ultra-high temperature ceramics (UHTCs) were prepared from a mixture powder of Zr/B4C/Si with different ratio via reactive hot pressing. The experimental results showed that the sintering temperature above 1800°C was necessary for enhancing the activity of the powders and thus improving the densification of the product. The sinterability and densification properties of ZrB2-based UHTCs meliorated with the amount of Si increasing. However, many large ZrB2 agglomerates formed when the amount of synthesized SiC in the product reached 25vol%, which led to decrease the mechanical property. The composite had highest mechanical properties when the volume ratio of ZrB2: SiC: ZrC was 73.86:20:6.14, and its flexual strength and the fracture toughness were 645.8MPa and 5.66MPa·m1/2 respectively. The microstructure investigation showed the in-situ formed SiC and ZrC were located in the triple point of ZrB2 grains with a size less than 3μm.


2019 ◽  
Vol 8 (4) ◽  
pp. 527-536 ◽  
Author(s):  
Zhaofu Zhang ◽  
Jianjun Sha ◽  
Yufei Zu ◽  
Jixiang Dai ◽  
Yingjun Liu

AbstractSelf-toughening ZrB2–SiC based composites are fabricated by in-situ reactive hot pressing. The effect of sintering additive content on the microstructure and mechanical properties of the composites is investigated. Microstructure observation found that the in-situ reactive hot pressing could promote the anisotropic growth of ZrB2 grains and the formation of interlocking microstructure. Such microstructure could improve the mechanical properties, especially, for the fracture toughness. The improved mechanical properties could be attributed to the self-toughening structure related to the ZrB2 platelets and the formed interlocking microstructure, which could trigger various toughening mechanisms such as grain pull-out, crack bridging, crack deflection, and crack branching, providing the main contribution to the high fracture toughness.


2020 ◽  
Author(s):  
Donglin Zhao ◽  
Tong Guo ◽  
X.M. Fan ◽  
Chao Chen ◽  
Yue Ma

Abstract The effect of pyrolytic carbon (PyC) thickness on the tensile property of mini T800-carbon fiber reinforced SiC matrix composites (mini-C/SiC) was studied in this work. PyC interphase was prepared by CVI process, and the PyC thickness was adjusted from 0 to 400 nm. The results showed that the tensile strength of mini-C/SiC first increased and then decreased with the increase of the PyC thickness. When the thickness of PyC was 100 nm, the average strength reached the maximum value of 393±70 MPa. Weibull modulus increased from 2.0 to 8.06 with the increase of PyC thickness, indicating that the increase of PyC thickness is conducive to reducing the dispersion of mechanical properties.


TANSO ◽  
1983 ◽  
Vol 1983 (113) ◽  
pp. 53-59 ◽  
Author(s):  
Sugio Otani ◽  
Akira Kojima ◽  
Shigeo Iizuka ◽  
Shingo Hoshino ◽  
Masashi Kozu

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1767
Author(s):  
Yuhong Jiao ◽  
Jianfeng Zhu ◽  
Xuelin Li ◽  
Chunjie Shi ◽  
Bo Lu ◽  
...  

Al matrix composite, reinforced with the in situ synthesized 3C–SiC, MgAl2O4, and MgO grains, was produced via the casting process using phenolic resin pyrolysis products in flash mode. The contents and microstructure of the composites’ fracture characteristics were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties were tested by universal testing machine. Owing to the strong propulsion formed in turbulent flow in the pyrolysis process, nano-ceramic grains were formed in the resin pyrolysis process and simultaneously were homogeneously scattered in the alloy matrix. Thermodynamic calculation supported that the gas products, as carbon and oxygen sources, had a different chemical activity on in situ growth. In addition, ceramic (3C–SiC, MgAl2O4, and MgO) grains have discrepant contents. Resin pyrolysis in the molten alloy decreased oxide slag but increased pores in the alloy matrix. Tensile strength (142.6 ± 3.5 MPa) had no change due to the cooperative action of increased pores and fine grains; the bending and compression strength was increasing under increased contents of ceramic grains; the maximum bending strength was 378.2 MPa in 1.5% resin-added samples; and the maximum compression strength was 299.4 MPa. Lath-shaped Si was the primary effect factor of mechanical properties. The failure mechanism was controlled by transcrystalline rupture mechanism. We explain that the effects of the ceramic grains formed in the hot process at the condition of the resin exist in mold or other accessory materials. Meanwhile, a novel ceramic-reinforced Al matrix was provided. The organic gas was an excellent source of carbon, nitrogen, and oxygen to in situ ceramic grains in Al alloy.


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