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1.
Intermediate temperature oxidative strength degradation of a SiC/SiNC composite with a polymer‐derived matrix
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David L. Poerschke Michael N. Rossol Frank W. Zok 《Journal of the American Ceramic Society》2017,100(4):1606-1617
The article describes an experimental investigation of oxidative degradation in mechanical performance of a SiC fiber‐reinforced composite with a SiCN matrix produced by polymer infiltration and pyrolysis. Tensile stress rupture and retained strength tests were performed at 800°C in dry air and in water vapor. Fracture surfaces were examined to determine the degree of fiber pull‐out and constituent oxidation and to measure radii of representative fiber fracture mirrors. The results indicate that degradation in tows adjacent to cut surfaces occurs equally rapidly in water vapor with or without application of stress; regions in the composite interior and near as‐processed (uncut) surfaces appear far less affected. Similar effects are evident but less pronounced in dry air. Although oxidation of fiber coatings is observed in some cases, collectively the results suggest that fiber degradation is the main mechanism leading to reduced composite strength. 相似文献
2.
Fabrication of SiC/diamond composite coatings by electrophoretic deposition and chemical vapor deposition
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Shengjie Yu Zhaofeng Chen Yang Wang Ruiying Luo Tengzhou Xu Ying Pan Jiahao Liao 《International Journal of Applied Ceramic Technology》2017,14(4):644-651
In this research, SiC/diamond composite coatings were fabricated by a novel procedure that consisted of the electrophoretic deposition (EPD) of diamond particles onto graphite substrates followed by chemical vapor deposition (CVD) of SiC. Various concentrations of MgCl2 were employed to increase the deposition rate and uniformity of the deposits during the EPD process by giving a positive charge to diamond particles. The CVD of SiC was found to have a tightly connected diamond‐graphite interface and spherical texture. With higher weight fraction of diamond particles deposits, the wear of steel ball increased, while the wear of SiC coating decreased. 相似文献
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4.
Jin Gao Yuelei Bai Haolong Fan Guangping Song Xiaocan Zou Yongting Zheng Xiaodong He 《Journal of the American Ceramic Society》2023,106(8):4877-4890
To understand the microscale toughening mechanism, the crack propagation, and stress–strain response of unidirectional SiCf/SiC composites with h-BN interphase under transverse and longitudinal tension are investigated by a promising micromechanical phase field (PF) method along with representative volume element. Of much interest, the calculation results are well consistent with the available experimental results. With a strong dependence on the interphase strength, the toughening mechanisms during crack propagation are well presented, for example, fiber pull-out, crack deflection, and interphase debonding. Furthermore, the longitudinal tensile strength of SiCf/SiC composites increases with decreasing the interphase strength, where only a weak enough interphase can result in a significant crack deflection by its cracking. In particular, the ratio of the interphase strength along fibers to the matrix strength should be less than 1.254 to ensure crack deflection in the interphase and fiber pull-out. Moreover, the transverse tensile strength of SiCf/SiC composites reaches a maximum with increasing the interphase thickness into the range of 0.25–0.5 µm. 相似文献
5.
Kazuya Shimoda Tatsuya Hinoki 《International Journal of Applied Ceramic Technology》2023,20(4):2466-2477
BN-nanoparticle-containing SiC-matrix-based composites comprising SiC fibers and lacking a fiber/matrix interface (SiC/BN + SiC composites) were fabricated by spark plasma sintering (SPS) at 1800°C for 10 min under 50 MPa in Ar. The content of added BN nanoparticles was varied from 0 to 50 vol.%. The mechanical properties of the SiC/BN + SiC composites were investigated thoroughly. The SiC/BN + SiC composites with a BN nanoparticle content of 50 vol.%, which had a bulk density of 2.73 g/cm3 and an open porosity of 5.8%, exhibited quasiductile fracture behavior, as indicated by a short nonlinear region and significantly shorter fiber pullouts owing to the relatively high modulus. The composites also exhibited high strength as well as bending, proportional limit stress, and ultimate tensile strength values of 496 ± 13, 251 ± 30, and 301 MPa ± 56 MPa, respectively, under ambient conditions. The SiC fibers with contents of BN nanoparticles above 30 vol.% were not severely damaged during SPS and adhered to the matrix to form a relatively weak fiber/matrix interface. 相似文献
6.
《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
7.
Michael W. Knauf Craig P. Przybyla Andrew J. Ritchey Rodney W. Trice R. Byron Pipes 《Journal of the American Ceramic Society》2020,103(2):1293-1303
The evolution of residual stresses found within a silicon carbide/silicon carbide (SiC/SiC) ceramic matrix composite through thermal treatments was investigated using Raman microspectroscopy. Constituent stress states were measured before, during, and after exposures ranging from 900 to 1300°C for varying times between 1 and 60 minutes. Silicon carbide particles in the as-received condition exhibited average hydrostatic tensile stresses of approximately 300 MPa when measured at room temperature before and after heat treatment. The room temperature Raman profile of the silicon matrix was altered in both shape and location with heat treatment cycles due to increasing activation of boron within the silicon lattice as heat treatment temperatures increased. By accounting for boron activation in the silicon–boron system, little to no permanent change of any constituent stresses were observed, and the silicon matrix subsequently exhibited a complimentary average hydrostatic compressive stress of approximately 300 MPa at room temperature, measured before and after heat treatment. This result builds upon previous literature and offers increased insight into boron activation phenomena measured through Raman spectroscopy methods. 相似文献
8.
Shaobing Li Na Ni Binbin Wu Chuanwei Li Qi Ding Zongbei He 《Journal of the European Ceramic Society》2021,41(12):5850-5862
The SiC fibers were coated with Ti3SiC2 interphase by dip-coating. The Ti3SiC2 coated fibers were heat-treated from 900 °C to 1100 °C in vacuum and argon atmospheres to comparatively analyze the effect of temperature and atmosphere on the microstructural evolution and mechanical strength of the fibers. The results show that the surface morphology of Ti3SiC2 coating is rough in vacuum and Ti3SiC2 is decomposed at 1100 °C. However, in argon atmosphere, the surface morphology is smooth and Ti3SiC2 is oxidized at 1000 °C and 1100 °C. At 1100 °C, Ti3SiC2 oxidized to form a thin layer of amorphous SiO2 embedded with TiO2 grains. Meanwhile, defects and pores appeared in the interphase scale. As a result, the fiber strength treated in the argon was lower than that treated in vacuum. The porous Ti3SiC2 interphase fabricated under vacuum was then employed to prepare the SiCf/SiC mini composite by chemical vapor infiltration (CVI) combined with precursor infiltration pyrolysis (PIP), and can effectively improve the toughness of SiCf/SiC mini composite. The propagating cracks can be deflected within the porous interphase layer, which promotes fiber pull-outs under the tensile strength. 相似文献
9.
Changtai Zhai Jinkai Xu Xiaoyu Nie Jiwen Tian Huadong Yu 《International Journal of Applied Ceramic Technology》2021,18(6):2273-2283
Based on the response surface methodology (RSM), laser-assisted micromachining (LAMM) experiments of carbon fiber reinforced silicon carbide matrix(C/SiC) composites have been carried out to obtain the data of three-direction cutting forces Fx, Fy, Fz, and result-force F in the cutting process. A stepwise regression method is used to screen out the factors that significantly affected the cutting force, and hence a multivariate nonlinear mathematical regression model has been established. Through the analysis of variance and regression analysis, the R2 of the regression model is the cutting force Fx: 0.975, the cutting force Fy: 0.970, the cutting force Fz: 0.972, the resultant force F: 0.987, and the probability p > F-values are all less than 0.001. The model analysis results show that the main effects and interactions of the three factors of laser power, cutting speed, and cutting depth significantly influence the cutting force. The main effect of the most considerable influence on the resultant F is cutting depth, followed by cutting speed and laser power, and the interactive effect is cutting speed and cutting depth. The experimental results show that the model prediction results are in good agreement with the experimental results. 相似文献
10.
Ravit Silverstein Frank W. Zok Carlos G. Levi 《Journal of the American Ceramic Society》2021,104(8):3833-3844
A two-step synthesis of SiC involving initial exposure of carbon surfaces to Si vapor, followed by Si melt infiltration, is investigated in this article with emphases on the mechanisms, kinetics, and microstructure evolution. Interrupted differential thermal analysis of amorphous C and Si powder mixtures and microstructure characterization are used to generate insight into the stages of the reaction. Exposure to Si vapor yields a SiC layer with nano-scale porosity driven by the volume change associated with the reaction. This forms a continuous pore network that promotes subsequent melt access to the reaction front with the C. While the pores remain open, the vapor phase reaction proceeds at a nearly constant rate and exhibits a strong temperature sensitivity, the latter due in part to the temperature sensitivity of the Si vapor pressure. The implications for enhancing the reactive melt infiltration process and fabrication of SiC matrices for ceramic composites are discussed. 相似文献
11.
《Journal of the European Ceramic Society》2017,37(4):1311-1320
A hybrid processing route based on vacuum infiltration, electrophoretic deposition, and hot-pressing was adopted to fabricate dense and tough SiCf/SiC composites. The as-received Tyranno SiC fabric preform was infiltrated with phenolic resin containing 5 wt.% FeO and SiC powders followed by pyrolysis at 1700 °C for 4 h to form an interphase. Electrophoretic deposition was performed to infiltrate the SiC-based matrix into the SiC preforms. Finally, SiC green tapes were sandwiched between the SiC fabrics to control the volume fraction of the matrix. Densification close to 95% ρtheo was achieved by incorporating 10 wt.% Al2O3-Sc2O3 sintering additive to facilitate liquid phase sintering at 1750 °C and 20 MPa for 2 h. X-ray diffraction and Raman analyses confirmed the catalytic utility of FeO by the formation of a pyrolytic carbon phase. The flexural response was explained in terms of the extensive fractography results and observed energy dissipating modes. 相似文献
12.
Clifton H. Bumgardner Frederick M. Heim David C. Roache Alex Jarama Morgan C. Price Christian P. Deck Xiaodong Li 《Journal of the American Ceramic Society》2021,104(1):481-491
Plain weave planar and biaxially braided tubular SiC/SiC CMCs are evaluated in tension and four-point bending, respectively, at ambient conditions. Custom-designed fixtures for CMC testing are developed for each loading mode and are coupled with three-dimensional digital image correlation. Stereoscopic image correlation analysis reveals crack initiation and failure sites to provide insight into stress redistribution mechanisms. Scanning electron microscopy is performed postmortem to determine the influence of microstructural features on crack initiation and failure. Crack spacing is measured in situ by stereoscopic image correlation and confirmed by SEM measurements to relate to underlying tow-tow crossing points. Triangulated surface heights of plain weave tow architecture are used to determine that subtle differences in neighboring transverse tow angle, which vary within a range of ±4° from horizontal, have no significant effect on final fracture location. The results presented reaffirm the state of current SiC/SiC CMCs developed for energy applications and will help to further improve SiC/SiC and other CMCs. 相似文献
13.
《Journal of the European Ceramic Society》2022,42(4):1197-1207
Titanium silicon carbide (Ti3SiC2) film was synthesized by molten salt synthesis route of titanium and silicon powder based on polymer-derived SiC fibre substrate. The pre-deposited pyrolytic carbon (PyC) coating on the fibre was utilized as the template and a reactant for Ti3SiC2 film. The morphology, microstructure and composition of the film product were characterized. Two Ti3SiC2 layers form the whole film, where the Ti3SiC2 grains have different features. The synthesis mechanism has been discussed from the thickness of PyC and the batching ratio of mixed powder respectively. Finally, the obtained Ti3SiC2 film was utilized as interphase to prepare the SiC fibre reinforced SiC matrix composites (SiCf/Ti3SiC2/SiC composites). The flexural strength (σF) and fracture toughness (KIC) of the SiCf/Ti3SiC2/SiC composite is 460 ± 20 MPa and 16.8 ± 2.4 MPa?m1/2 respectively. 相似文献
14.
《Journal of the European Ceramic Society》2022,42(13):5323-5333
To predict the effects of Si doping on hexagonal boron nitride (h-BN) and to achieve a balance between mechanical and oxidation properties for the interphase modification in SiCf/SiC composites, we herein calculate and analyze the crystal structures and mechanical properties of (BN)64Six (x = 4, 8, 16, 32) models by means of density functional theory (DFT) calculations and ab initio molecular dynamics (aiMD) simulations. The possible trends of crack deflection and self-healing ability are discussed. The modeling shows an obvious transition of (BN)64Six from the layered crystal structure and anisotropic mechanical property to amorphous structure and isotropic mechanical property as the Si doping content up to 36.1 wt%. Regarding to the application of interphase in SiCf/SiC composites, (BN)64Si16 model structure possess the highest debonding potential according to Cook and Gordon’s criteria and illustrates the higher self-healing capacity at elevated temperature. 相似文献
15.
Rong Xue Jiping Wang Yiming Chen Zhejian Zhang Zhichao Xiao Hongyan Xia 《Journal of the American Ceramic Society》2023,106(10):6317-6329
The appropriate carbon content is indispensable for the application of self-lubricating graphite/SiC composites. However, it is a big challenge to retain high carbon content in the reaction-formed graphite/SiC composites because of drastic consumption of carbon by violent reaction with liquid silicon. In this study, a hybrid powder constructed by graphite particles (G) and glassy carbon derived from phenolic resin (PFC) was used as carbon sources, or PFC@G for short, to reserve higher content of carbon in the reaction-formed composites. The weight ratio of phenolic resin to graphite particles was adjusted to obtain an appropriate PFC@G with dense microstructure and close-grained surface. Compared with the graphite/SiC composites only using raw graphite particles as carbon sources, the carbon content of the composites fabricated with compact and large PFC@G has obviously increased (up to 172%). In particular, the carbon content of the composites fabricated with the weight ratio = 0.8 reached a high value of 44.26 vol.%, which exhibited outstanding self-lubrication properties among the four kinds of the composites. The mechanism of reserving higher content of carbon in the graphite/SiC composites by constructing PFC@G is investigated, revealing that a continuous SiC layer formed on the surface of the larger size PFC@G and most closely packed graphite particles inside of PFC@G were insulate from liquid silicon by the layer. 相似文献
16.
Chen Hu Joseph F. Labuz Takaaki Koyanagi Jia-Liang Le 《Journal of the American Ceramic Society》2023,106(5):3066-3077
Silicon carbide (SiC) fiber-reinforced SiC matrix (SiC/SiC) composites have emerged as a new material candidate for fuel claddings in light water reactors. Recent studies showed that the load capacity of SiC/SiC materials exhibits a considerable statistical variation. Therefore, reliability analysis plays a critical role in design of SiC/SiC composite claddings. This paper presents a probabilistic model for the lifetime distribution of SiC/SiC composites. The model is anchored by a multiaxial stress-based failure criterion and subcritical damage accumulation mechanism. Based on the kinetics of subcritical damage growth, the lifetime distribution of a laboratory test specimen for any given loading history can be calculated. A finite weakest-link model is used to extrapolate the lifetime distribution of test specimens to full-length claddings. It is shown that the damage accumulation mechanism has a strong influence on the lifetime distribution of the cladding. This finding highlights the importance of understanding the static fatigue behavior of SiC/SiC composites. The present analysis also demonstrates an intricate length effect on the failure probability of the cladding, which is expected to play a crucial role in design extrapolation. 相似文献
17.
Xiaoqing Zhao Ji Zou Aiyang Wang Weimin Wang Zhengyi Fu 《Journal of the American Ceramic Society》2023,106(2):829-835
Effects of SiC whiskers (SiCw) on the mechanical properties of composites largely depend on their thermal stability at high temperature. In this study, pure SiCw and Ti3SiC2 coated SiCw were thermal treated at 1600–1800°C for 1 h. Their phase assemblage, morphology, and structural evolution were investigated. Oxygen partial pressures in the graphite furnace resulted in the breakdown of SiCw into particles at 1600°C, and the degradation became more pronounced with temperature increasing. The thermal stability of SiC whiskers at 1600–1700°C was significantly improved by a thin Ti3SiC2 coating on them, as both thermodynamic calculations and experimental observations suggest Ti3SiC2 coating could be preferentially oxidized/decomposed, prior to the active oxidation of SiC. At 1800°C, the protective role of the coating on the whiskers became weakened. SiC was converted into gaseous SiO and CO, with the remaining of interconnected TiC micro-rods and amorphous carbon. 相似文献
18.
《Journal of the European Ceramic Society》2014,34(5):1131-1138
Cylindrical SiC-based composites composed of inner Si/SiC reticulated foam and outer Si-infiltrated SiC fiber-reinforced SiC (SiCf/Si/SiC) skin were fabricated by the electrophoretic deposition of matrix particles into SiC fabrics followed by Si-infiltration for high temperature heat exchanger applications. An electrophoretic deposition combined with ultrasonication was used to fabricate a tubular SiCf/SiC skin layer, which infiltrated SiC and carbon particles effectively into the voids of SiC fabrics by minimizing the surface sealing effect. After liquid silicon infiltration at 1550 °C, the composite revealed a density of 2.75 g/cm3 along with a well-joined interface between the inside Si/SiC foam and outer SiCf/Si/SiC skin layer. The results also showed that the skin layer, which was composed of 81.4 wt% β-SiC, 17.2 wt% Si and 1.4 wt% SiO2, exhibited a gastight dense microstructure and the flexural strength of 192.3 MPa. 相似文献
19.
Microstress in the SiC: Si matrix of a ceramic matrix composite (CMC) has been characterized, using Raman spectroscopy. The matrix of the composite was manufactured using liquid melt infiltration, and has about 20% unreacted free silicon. During the processing of the composite, the unreacted free silicon expands 11 vol% when transforming from liquid to solid. This crystallization expansion creates compressive microstress in the silicon phase of the matrix, which ranges from 2.4 to 3.1 GPa, and tensile microstress in the SiC of the matrix which ranges from 0.24 to 0.75 GPa. The microstress varies significantly with position, following a normal distribution. 相似文献
20.
Rebecca B. Reitz Frank W. Zok Carlos G. Levi 《Journal of the American Ceramic Society》2017,100(12):5471-5481
A comparative study of reactive melt infiltration using Si and Si‐Y alloys is presented to provide insight into the governing processes that control the effectiveness of the melt interaction with a carbonaceous preform and the temperature capability of the SiC matrix for ceramic matrix composites. Through experiments on two substantially different scales of capillaries in porous graphite tubes using Si and Si‐Y alloys, the current study has characterized the phenomena that play a role in the infiltration of the melt and its reaction with the preform. It is shown that (i) the interface reaction controls wetting in both large and small capillaries and the climb rate is enhanced by the presence of Y; (ii) reaction choking occurs at critical throats within the pore network, usually behind the infiltration front; and (iii) different residual silicides can form during reaction and upon cooling. A potential mechanism for SiC growth is described, and the implications for the interplay between SiC growth and infiltration are discussed. 相似文献