共查询到20条相似文献,搜索用时 31 毫秒
1.
《Ceramics International》2017,43(6):4880-4887
To improve oxidation resistance of carbon/carbon (C/C) composites, a multiphase double-layer ZrB2-CrSi2-SiC-Si/SiC coating was prepared on the surface of C/C composites by pack cementation. Thermogravimetry analysis showed that the as-prepared coating could provide effective oxidative protection for C/C composites from room temperature to 1490 °C. After thermal cycling between 1500 °C and room temperature, the fracture behaviors of the as-prepared specimens changed and their residual flexural strengths decreased as thermal cycles increased. The specimen after 20 thermal cycles presented pseudo-plastic fracture characteristics and relatively high residual flexural strength (83.1%), while the specimen after 30 thermal cycles failed catastrophically without fiber pullout due to the severe oxidation damage of C/C substrate especially the brittleness of the reinforcement fibers. 相似文献
2.
Oxidation of SiC/BN/SiC ceramic matrix composites in dry and wet oxygen at intermediate temperatures
《Journal of the European Ceramic Society》2022,42(10):4110-4120
The oxidation behavior of SiC/BN/SiC ceramic matrix composites (CMCs) was evaluated from 400° to 800 °C in 100% O2 and 50% H2O/50% O2 gas mixtures. Thermogravimetric analysis (TGA) was utilized to measure weight change during controlled environment exposures at elevated temperatures for 1 and 50 hours. Oxidized CMCs and their oxides were studied post-exposure with scanning electron microscopy and energy dispersive spectroscopy. The oxidation onset and composition transition temperatures were evaluated. Key observations include oxide composition, oxide wetting, oxygen solubility in Hi-Nicalon SiC fibers and BN fiber coating oxidation and volatility behavior as a function of temperature. Degradation in wet environments at 600 °C was most extensive due to the formation of a non-wetting, non-protective surface oxide, allowing oxidant access to the BN fiber coatings followed by oxidation and volatilization. Implications of the CMC oxidation behavior are discussed for CMCs in service. 相似文献
3.
《Ceramics International》2019,45(10):12764-12772
On account of the excellent oxidation resistance of precursor-derived SiBCN ceramics, carbon-fiber-reinforced SiBCN (C/SiBCN) composites are increasingly being used in high-temperature aerospace applications. However, very few studies have investigated the high-temperature oxidation behavior of C/SiBCN composites for their application to high-heat engines. Herein, C/SiBCN composites prepared by precursor infiltration and pyrolysis were tested in static air up to an oxidation temperature of 1700 °C. The composites’ structural evolution after oxidation and their potential oxidation mechanisms were investigated in detail. The carbon fibers were preferentially oxidized at temperatures in the range of 1200–1500 °C and completely oxidized at 1500 °C. The oxidation of the fibers at 1500 °C resulted in the formation of abundant oxygen channels and consequently a high oxide scale growth rate of 5–7 μm2 h−1 and a large mass loss of 54.6 wt%. At elevated temperatures in the range of 1600–1700 °C, a dense SiO2 oxide layer was formed by the sacrificial oxidation of the SiBCN matrix. The oxidation rate of the composites was therefore controlled by the diffusion rate of oxygen through the protective SiO2 oxide layer and the weight loss of the composites decreased to 28.6% after oxidation at 1600 °C for 60 min. The structural integrity of the composites was maintained after long-term oxidation at 1600 °C. 相似文献
4.
《Ceramics International》2020,46(5):5937-5945
SiC whisker coating was prepared on the surface of C/C composite successfully by CVD, and transient liquid phase (TLP) diffusion bonding was employed to realize the joining of SiC whisker coating modified C/C composite and Ti2AlNb alloy using Ti–Ni–Nb foils as interlayer. The microstructure, shear strength and fracture behavior were investigated by scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD) and universal testing machine. The results show that SiC has good compatibility with C/C composite, and gradient interface formed between SiC-modified C/C composite and Ti2AlNb alloy. When the bonding experiment was carried out under bonding temperature of 1040 °C and holding time of 30min with 5 MPa pressure in vacuum, the joints formed well and no obvious defects can be observed. The typical microstructure of joints is C/C composite/SiC + TiC/Ti–Ni compounds + Ti–Ni–Nb solid solutions/residual Nb/diffusion reaction layer/Ti2AlNb alloy. With the increasing of bonding temperature, the thickness of joining area increased due to sufficient element diffusion. However, when bonding temperature is elevated to 1060 °C, some defects such as cracks and slag inclusions exist in the interface layer between interlayer and Ti2AlNb. The joints with maximum average shear strength of 32.06 MPa are bonded at 1040 °C for 30min. C, SiC and TiC can be found on the fracture surface of joints bonded at 1040 °C which indicated that fracture occurred at the interface layer adjacent SiC layer. 相似文献
5.
《Ceramics International》2016,42(14):15479-15484
Oxidation behaviour of two-dimensional (2D) C/SiC composites with 0, 1 and 2 mm average diameter holes has been investigated in air at 700 °C. Oxidation tests, mechanical tests, microstructural characterization and computed tomography (CT) were performed to find the effect of hole defects on the oxidation behaviour of C/SiC composites. The experimental results pointed out that the thermal exposure area (TEA) ratio and oxidation time were two key affecting factors on the oxidation behaviour. Weight loss was found to accelerate at oxidation durations higher than 1 h, thereafter residual tensile strength also dropped. A TEA ratio of 16% was found as critical in severely downgrading the residual tensile strength and significantly weakening the oxidation resistance behaviour for C/SiC composites contain hole defects. 相似文献
6.
《Ceramics International》2021,47(24):34783-34793
C/C–SiC composites are considered to be strong candidates for the new generation of high-speed train brake discs. To achieve a better application, it is necessary to improve understanding of the oxidation behaviour of C/C–SiC brake discs after a full-scale bench test rig. In this study, full-scale braking bench tests for C/C–SiC self-mated brake pairs were conducted under a braking speed of 350–420 km/h and a braking pressure of 17–28 kN. Moreover, the oxidation behaviour and mechanisms of the C/C–SiC brake discs during the practical braking process were investigated. The results indicate that the oxidation behaviour is highly dependent on the friction surface region of the C/C–SiC brake disc owing to the distribution of microcracks, the formation of friction films, the difference in temperature, and the contact content with O2. Specifically, the oxidation depths of the friction layer on the inner circumferential surface, middle friction surface, and outer circumferential surface were 278.3, 252.1, and 359.9 μm, respectively. Furthermore, the oxidation reaction preferentially occurs in the active area of the C fibre and pyrolytic carbon (PyC) during the braking process. 相似文献
7.
Manish Patel M. Phani S. Kiran Sweety Kumari Vijender Singh Sarabjit Singh V.V. Bhanu Prasad 《Ceramics International》2018,44(2):1633-1640
The effect of oxidation and thermal residual stress on mechanical properties of SiC seal coated C/SiC composite at ambient temperature and high temperature were studied. The oxidation of SiC seal coated C/SiC composite at 1300 and 1500 °C resulted in carbon fibres burn area near through thickness micro cracks in the SiC seal coating. With the increase in exposure time, the formation of SiO2 layer in SiC matrix near carbon fibres burns area was found. Residual mechanical properties of SiC seal coated C/SiC composite after exposure in air show significant degradation. First time, a continuous measurement of Young's modulus with temperature of C/SiC composite was carried out using an impulse excitation technique. The effect of relaxation of thermal residual stress on mechanical properties was observed with the help of continuous measurement of Young's modulus as a function of temperature in an inert atmosphere. 相似文献
8.
Pre-oxidized fibers as reinforcement are candidates for reducing the overall cost of C/C composites with superior properties. This study investigated the dynamic oxidation and protection of the pre-oxidized fiber C/C composites (Pr-Ox-C-C). According to the Arrhenius equation, the oxidation kinetics of the Pr-Ox-C-C consisted of two different oxidation mechanism with the transition point was at about 700 °C. Scanning electron microscopy investigation showed that oxidation initiated from the fiber/matrix interface of composites, whereas the matrix carbon was easily oxidized. To improve the anti-oxidant properties of Pr-Ox-C-C, a ceramic powder-modified organic silicone resin/ZrB2-SiC coating was prepared by the slurry method. The coated samples were subjected to isothermal oxidation for 320 h at 700 °C, 800 °C, 900 °C, 1000 °C and 1100 °C with incurred weight losses of ? 1.6%, 0.77%, ? 1.28%, 0.68% and 1.19%, respectively. After 110 cycles of thermal shock between 1100 °C and room temperature, a weight loss of 1.30% was obtained. The Arrhenius curve presented four different phases and mechanisms for coating oxidation kinetics. The excellent oxidation resistance properties of the prepared coating could be attributed to the inner layer which was able to form B2O3-Cr2O3-SiO2 glass to cure cracks, and the ZrB2-SiC outer layer that could provide protective oxides to reduce oxygen infiltration and to seal bubbles. 相似文献
9.
《Journal of the European Ceramic Society》2022,42(13):5419-5431
To improve the mechanical properties of C/C composites, the SiC(N)/TiC ceramic derived from single-source precursors (SSPs) were introduced into the C/C by precursor infiltration and pyrolysis (PIP) at 1100 °C. The shear strength of all modified composites were improved by nearly 2 times compared with the pristine C/C composites (37.4 MPa) due to the increased interfaces by multiphases incorporation. After further annealing at 1500 °C, the SiC(N)/TiC ceramic in C/C composite transferred into the nanocomposites, SiC(N)/TiC-NCs, in which nano-scale TiC particles distributed into the SiC(N) matrix. The modified samples still exhibited about 39% improvement on shear strength. Large numbers of uniform micro-cracks occurred in both above SSPs derived ceramic cases, reducing stress concentration during the shear testing. Moreover, some ring-shaped cracks were observed in the fracture region which can consume large amounts of energy in crack propagation process and then benefit to improve the shear strength. 相似文献
10.
《Journal of the European Ceramic Society》2023,43(11):4645-4655
Matrix modification is of great significance for the densification of CVI-SiC/SiC, as well as the improvement of self-healing and oxidation resistance. A eutectic component of Y2O3-Al2O3-SiO2 system modified with CaO (CYAS) was used in this study to modify SiC/SiC at 1400 °C. The oxidation behaviour of the composites was investigated under dry/water oxygen atmosphere at 900 °C and 1300 ℃. Compared to the relatively dense SiC/SiC, the modified SiC/SiC showed a slight increase in flexural strength and fracture toughness at room temperature, as well as a significant increase in oxidation resistance and densification. Our work provides a low-cost, simple-to-operate, short-cycle densification method for CVI-SiC/SiC composites that increases their oxidation resistance without compromising their mechanical properties at room temperature. 相似文献
11.
《Ceramics International》2022,48(5):6402-6413
In this paper, the characteristics and mechanism of laser-assisted machining (LAM) of C/SiC composites with different fiber orientations (0°, 45°, 90°, 135°) are studied. For the purpose of this study, a series of LAM experiments have been carried out and supported by a comparative analysis over the conventional machining (CM). Furthermore, the effect of fiber orientation on surface morphology, roughness, and sub-surface damage was explored. It is found that the surface quality of the workpiece treated by LAM is better than that of CM, and a lower surface roughness Ra value is obtained. It is shown that depending on different fiber orientations, the surface roughness decreases in different degrees. The roughness at 90° fiber orientation witnesses the maximum reduction, followed by 0° and 45° fiber orientation, and the roughness at 135° fiber orientation undergoes the slightest reduction. Moreover, surface micro-defects under LAM are significantly reduced, and fiber fractures are tidier. On the other hand, the matrix is mixed with fiber debris under high temperatures and sticks to the machined surface, filling and repairing surface pits and holes and hence improving the processed surface quality. These results provide new guidance for improving the machining quality of C/SiC composites. 相似文献
12.
《Journal of the European Ceramic Society》2022,42(5):1884-1892
In order to improve the oxidation resistance of C/C-SiC composites, a SiC coating was prepared on a C/C-SiC composite by slurry painting combined with a chemical vapor reaction process. The oxidation resistance and microstructural evolution of the coated samples were investigated. The results show that the as-prepared SiC coating contained a large amount of residual silicon, and the presence of these Si promoted the formation of a complete SiO2 glass layer in the initial stage of oxidation. However, the evaporation of the residual Si also accelerated the failure of the SiC coating, which caused the weight loss of the sample to be about 2.2% after oxidation in static air at 1500 °C for 300 h. Attributed to a large number of SiC ceramics in the C/C-SiC composite, the oxidation weight loss rate of the coating sample after coating failure was reduced. 相似文献
13.
Lingwei Yang Xueren Xiao Li Jing Jun Zhang Liping Liu Changhao Zhao Guolin Wang 《Journal of the European Ceramic Society》2021,41(10):5388-5393
A plasma wind tunnel was utilized to explore the dynamic oxidation mechanism of SiC fiber reinforced SiC matrix composite in high-enthalpy plasmas. The results suggest the occurrences of active and passive oxidations on SiC fiber/matrix with atomic oxygen at 900~1600 °C and 1~6 kPa. Increasing plasma pressure could retard the active oxidation and promote the passive oxidation. Severe corrosion of SiC fibers due to active oxidation is highlighted. The as-formed SiO2 layers cannot fully seal the open porosities and the interfacial gaps formed by oxidation of pyrocarbon interphases. This led to penetration of oxidized species and failure of fiber bundles directly exposed to heat flows. In addition, the spatial heat flux and temperature distributions were not homogeneous on the oxidized surface, which triggered early ‘temperature jump’ at ≈1600 °C (≈4.5 kPa) and severe localized ablation. If sealing the composite surface with SiC coating, the ablation resistance was significantly improved. 相似文献
14.
Liuwei Li Hao Qin Chunjing Liao Xiao You Han Luo Yudong Xue Xuezheng Yue Jinshan Yang Xiangyu Zhang Shaoming Dong 《International Journal of Applied Ceramic Technology》2024,21(3):2183-2195
Silicon carbide fiber-reinforced SiC ceramic matrix composites (SiCf/SiC CMCs) based on a domestic KD-SA SiC fiber were exposed to a wet oxygen atmosphere for 135 h at 800, 1100, and 1300°C. The evolution of the microstructure and mechanical properties of SiCf/SiC CMCs have been systematically investigated following oxidation. For weight change, CMC-1300 showed the greatest gain (0.394%), followed by CMC-1100 (0.356%) and CMC-800 (0.149%). The volatilization of boron oxide (B2O3) combined with the slight oxidation of the SiC matrix at 800°C caused crack deflection and fiber pull-out. The complete dissipation of the interphase could be found when the oxidation temperature increases to 1100°C, generated a fracture surface with brittle fracture characteristics. At 1300°C, crystalline SiO2 hindered oxygen diffusion, with evidence of fiber pull-out. Based on thermodynamic calculations and microscopic observations, we propose a mechanism to explain the thermal degradation of SiCf/SiC CMCs. This work offers valuable guidance for the fabrication of SiCf/SiC CMCs that are suitable for high-temperature applications. 相似文献
15.
《Ceramics International》2020,46(4):4351-4357
A porous morph-genetic SiC/C ceramic material was fabricated using biomass-derived C template, Si powder, and Fe(NO3)3·9H2O as the starting materials. The effects of heating temperature, and catalyst/Si mole ratio on the formation of SiC/C ceramic were investigated. In addition, the pore size distribution was obtained through pore size analysis, and the determination of oxidation resistance of SiC/C ceramics and C template was carried out by thermogravimetric analysis. The results show that copious amounts of SiC nanowires, which were distributed on the surfaces and interiors of the C template holes, were formed at 1300 °C with 4 wt% Fe as catalyst. The SiC nanowires significantly affected the oxidation resistance and microporous structures of the prepared materials. Moreover, a possible formation mechanism for the porous SiC/C ceramic was determined. 相似文献
16.
Wen Jin Zhou Si Yi Lu Sun Bei-zhi Wang Yi Li Guang-de Xing Zhong-fang Cao Jie He Heng-ping Xiang Yang 《Ceramics International》2018,44(14):16583-16588
Polymer infiltration pyrolysis (PIP) was used to prepare carbon fiber-reinforced silicon carbide (C/SiC) composites, and chemical vapor deposition (CVD) was employed to fabricate SiC coating. The oxidation behavior at 1700?°C and the flexural property at 1200?°C were tested. SiC coating exerted remarkable oxidation effects on PIP-C/SiC composites. In the absence of coating, PIP-C/SiC composites lost 29.2% of its mass, with merely 6.74% of the original flexural strength retained. In contrast, CVD-SiC coated PIP-C/SiC composites had the mass loss of 10.2% and the flexural strength retention ratio of 23.4%. In high-temperature tests, SiC coating played an important role in the flexural strength of PIP-C/SiC composites. The flexural strength of uncoated composites became 330.7?MPa, and that of coated ones reduced from 655.3 to 531.2?MPa. 相似文献
17.
18.
Oxidation Mechanisms and Kinetics of 1D-SiC/C/SiC Composite Materials: I, An Experimental Approach 总被引:2,自引:0,他引:2
Ludovic Filipuzzi Gerald Camus Roger Naslain Jacques Thebault 《Journal of the American Ceramic Society》1994,77(2):459-466
The oxidation of unidirectional SiC/C/SiC model composites has been investigated through thermogravimetric analysis, optical/electron microscopy, and electrical measurements. The influence of temperature and carbon interphase thickness on the oxidation of the composites is discussed. The oxidation involves three phenomena: (i) reaction of oxygen with the carbon interphase resulting in pores around the fibers, (ii) diffusion of oxygen and carbon oxides along the pores, and (iii) reaction of oxygen with the pore walls leading to the growth of silica layers on both the fibers and matrix. In composites with a thin carbon interphase (e.g., 0.1 μm) treated at T > 1000°C the pores are rapidly scaled by silica. Under such conditions, the oxidation damages are limited to the vicinity of the external surface and the materials exhibit a self-healing character. Conversely, long exposures (300 h) at 900°C give rise to the formation of microcracks in the matrix related to mechanical stresses arising from the in situ SiC/SiO2 conversion, fly, the self-healing character is not observed in composites with a thick interphase (e.g., 1 μm) since carbon is totally consumed before silica can seal the pores. 相似文献
19.
《Journal of the European Ceramic Society》2022,42(1):52-70
C/C-BN-SiC composite was prepared by ceramic slurry infiltration combined with resin impregnation and carbonization, and the matrix with continuous distributed self-healing phase was obtained. In this study, the kinetic characteristics and oxidation behavior of the composites with various h-BN/SiC ratios in the temperature range of 600~1300°C were studied by combining the isothermal oxidation test with the kinetic model. The optimal h-BN/SiC ratio balances the thermal stability and fluidity of the oxidized product, which not only has high thermal stability and low oxygen permeability to acts as an oxygen diffusion barrier but also has a certain fluidity to seal defects. 相似文献
20.
《Ceramics International》2023,49(10):14989-14996
In this paper, the torsion and flexural-torsional coupled mechanical properties of different C/SiC torque tubes were investigated for the testing condition at room and elevated temperatures. Effects of fiber types, fiber preforms, and small hole during fabrication process on torsion mechanical properties were investigated. Flexural-torsional coupled mechanical tests for C/SiC torque tubes with different external diameter and wall thickness were conducted at room and elevated temperatures. The torsion and flexural moments and corresponding shear and flexural strength were obtained. The fracture surface and cracks propagation path were observed and analyzed. The torque and shear strength in T300™-3k torque tube were much higher than those of T300™-1k torque tube. Among 3D needled (3DN), 2D plain-woven [0°/90°] and [±45°] C/SiC torque tubes, the density, torque, and shear strength of 3DN-C/SiC torque tube were the highest. For the C/SiC torque tubes with small hole, the small hole not only increased the densification and uniformity (axial and radial) of the torque tube, but also has the potential to make the damage cracks more zigzag, which improved the fracture toughness of the torque tubes. 相似文献