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1.
C/C–ZrC–SiC composites with continuous ZrC–SiC ceramic matrix were prepared by a multistep technique of precursor infiltration and pyrolysis process. Ablation properties of the composites were tested under an oxyacetylene flame at 3000 °C for 120 s. The results show that the linear ablation rate of the composites was about an order lower than that of pure C/C and C/C–SiC composites as comparisons, and the mass of the C/C–ZrC–SiC composites increased after ablation. Three concentric ring regions with different coatings appeared on the surface of the ablated C/C–ZrC–SiC composites: (i) brim ablation region covered by a coating with layered structure including SiO2 outer layer and ZrO2–SiO2 inner layer; (ii) transition ablation region, and (iii) center ablation region with molten ZrO2 coating. Presence of these coatings which acted as an effective oxygen and heat barrier is the reason for the great ablation resistance of the composites. 相似文献
2.
《Journal of the European Ceramic Society》2014,34(2):171-177
C/C–SiC composites were prepared by molten infiltration of silicon powders, using porous C/C composites as frameworks. The porosities of the C/C–SiC composites were about 0.89–2.8 vol%, which is denser than traditional C/C composites. The ablation properties were tested using an oxyacetylene torch. Three annular regions were present on the ablation surface. With increasing pyrocarbon fraction, a white ceramic oxide layer formed from the boundary to the center of the surface. The ablation experimental results also showed that the linear and mass ablation rates of the composites decreased with increasing carbon fraction. Linear SiO2 whiskers of diameter 800 nm and length approximately 3 μm were formed near the boundaries of the ablation surfaces of the C/C–SiC composites produced with low-porosity C/C frameworks. The ablation mechanism of the C/C–SiC composites is discussed, based on a heterogeneous ablation reaction model and a supersaturation assumption. 相似文献
3.
《Journal of the European Ceramic Society》2020,40(3):651-659
To improve the ablation resistance under the ultra-high temperature, the matrix of the carbon/carbon (C/C) composite was modified with a ternary ceramic of SiC–ZrC–TiC via reactive melt infiltration. The obtained ceramic matrix was composed of Zr-rich and Ti-rich solid solution phases of Zr1−xTixC and SiC. This composite exhibited an excellent ablation property at 2500 °C with low mass and linear ablation rates of 0.008 mg s−1 cm−2 and 0.000 μm s−1, respectively. The ablation mechanism was revealed with various microstructure characterizations and compared with those of C/C–SiC and C/C–TiC composites. Results showed that the degradations of these composites were primarily caused by the loss of the protective oxide scale via volatilization under the ultra-high temperature and flushing by high-speed airflow. The high ablation resistance of the C/C–SiC–ZrC–TiC composite was attributed to the protection of a multiphase oxide scale with high viscosity and low volatility. 相似文献
4.
Sandan Kumar Sharma B. Venkata Manoj Kumar Kwang-Young Lim Young-Wook Kim S.K. Nath 《Ceramics International》2014
Dense silicon carbide (SiC) ceramics were prepared with 0, 10, 30 or 50 wt% WC particles by hot pressing powder mixtures of SiC, WC and oxide additives at 1800 °C for 1 h under a pressure of 40 MPa in an Ar atmosphere. Effects of alumina or SiC erodent particles and the WC content on the erosion performance of sintered SiC–WC composites were assessed. Microstructures of the sintered composites consisted of WC particles distributed in the equi-axed grain structure of SiC. Fracture surfaces showed a mixed mode of fracture, with a large extent of transgranular fracture observed in SiC ceramics prepared with 30 wt% WC. Crack bridging by WC enhanced toughening of the SiC ceramics. A maximum fracture toughness of 6.7 MPa*m1/2 was observed for the SiC ceramics with 50 wt% WC, whereas a high hardness of 26 GPa was obtained for the SiC ceramics with 30 wt% WC. When eroded at normal incidence, two orders of magnitude less erosion occurred when SiC–WC composites were eroded by alumina particles than that eroded by SiC particles. The erosion rate of the composites increased with increasing angle of SiC particle impingement from 30° to 90°, and decreased with WC reinforcement up to 30 wt%. A minimum erosion wear rate of 6.6 mm3/kg was obtained for SiC–30 wt% WC composites. Effects of mechanical properties and microstructure on erosion of the sintered SiC–WC composites are discussed, and the dominant wear mechanisms are also elucidated. 相似文献
5.
《Ceramics International》2016,42(4):5171-5176
C/SiC–ZrC composites were prepared by a combining slurry process with precursor infiltration and pyrolysis, and then annealed from 1200 °C to 1800 °C. With rising annealing temperature, their mass loss rate increased, and the flexural strength and modulus decreased from 227.9 MPa to 41.3 MPa and from 35.3 GPa to 22.7 GPa, respectively. High-temperature annealing, which elevated thermal stress and strengthened interface bonding, was harmful to the flexural properties. However, it improved the ablation properties by increasing the crystallization degree of SiC matrix. The mass loss rate and linear recession rate decreased with increasing annealing temperature and those of the samples annealed at 1800 °C were 0.0074 g/s and 0.0011 mm/s respectively. Taking mechanical and ablation properties into consideration simultaneously, the optimum annealing temperature was 1600 °C. 相似文献
6.
《Ceramics International》2020,46(11):18895-18902
In order to improve the ablation and oxidation resistance of C/C–ZrC–SiC composites in wide temperature domain, “Z-pins like” Zr–Si–B–C multiphase ceramic rods are prepared in the matrix. The influence of different sintering temperatures on the microstructure of ceramic rods and the ablative behavior of heterogeneous composites are studied. The results showed that the ZrB2 and SiC phases are formed in the sintered matrix, and the increase of sintering temperature is beneficial to improve the density of the ceramic rods. The ablation properties of samples have been greatly improved. The mass and linear ablation rate are 0.8 mg/s and 3.85 μm/s, respectively, at an ablation temperature of 3000 °C and an ablation time of 60 s. After ablation, the matrix surface is covered with SiO2 and ZrO2 mixed oxide films. This is due to the preferential oxidation of “Z-pins like” Zr–Si–B–C multiphase ceramic rods in the ablation process, and B2O3 melt, SiO2 melt, borosilicate glass, ZrSiO4 melt and ZrO2 oxide film can be generated successively from the low-temperature segment to the ultra-high temperature segment. These oxidation products can be used as compensation oxide melts for the healing of cracks and holes on the matrix surface in different temperature ranges and effectively prevent the external heat from spreading into the matrix. Therefore, C/C–ZrC–SiC composites with “Z-pins like” Zr–Si–B–C multiphase ceramic rods achieve ablation resistance in wide temperature domain. 相似文献
7.
《Ceramics International》2020,46(1):156-164
Spark plasma sintering (SPS) route was employed for preparation of quadruplet ZrB2–SiC–ZrC–Cf ultrahigh temperature ceramic matrix composites (UHTCMC). Zirconium diboride and silicon carbide powders with a constant ZrB2:SiC volume ratio of 4:1 were selected as the baseline. Mixtures of ZrB2–SiC were co-reinforced with zirconium carbide (ZrC: 0–10 vol%) and carbon fiber (Cf: 0–5 vol%), taking into account a constant ratio of 2:1 for ZrC:Cf components. The sintered composite samples, processed at 1800 °C for 5 min and 30 MPa punch press under vacuumed atmosphere, were characterized by densitometry, field emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry as well as mechanical tests such as hardness and flexural strength measurements. The results verified that the composite co-reinforced with 5 vol% ZrC and 2.5 vol% Cf had the optimal characteristics, i.e., it reached a relative density of 99.6%, a hardness of 18 GPa and a flexural strength of 565 MPa. 相似文献
8.
Yehong Cheng Fan Zhang Denghao Ma Yixin Zhang Yaxiong Liu Yumin An Anzhe Wang Ning Hu Libin Zhao Wenbo Han 《International Journal of Applied Ceramic Technology》2023,20(3):1636-1645
Although Cf/ZrB2–SiC composites prepared via direct ink writing combined with low-temperature hot-pressing were shown to exhibit high relative density, high preparation efficiency, and excellent flexural strength and fracture toughness in our previous work, their oxidation and ablation resistance at high and ultrahigh temperatures had not been investigated. In this work, the oxidation and ablation resistance of Cf/ZrB2–SiC composites were evaluated via static oxidation at high temperature (1500°C) and oxyacetylene ablation at ultrahigh temperatures (2080 and 2270°C), respectively. The thickness of the oxide layer of the Cf/ZrB2–SiC composites is <40 μm after oxidizing at 1500°C for 1 h. The Cf/ZrB2–SiC composites exhibit non-ablative properties after oxyacetylene ablation at 2080 and 2270°C for >600 s, with mass ablation rates of 3.77 × 10−3 and 5.53 × 10−3 mg/(cm2 s), and linear ablation rates of −4.5 × 10−4 and −5.8 × 10−4 mm/s, respectively. Upon an increase in the ablation temperature from 2080 to 2270°C, the thickness of the total oxide layer increases from 360 to 570 μm, and the carbon fibers remain intact in the unaffected region. Moreover, the oxidation and ablation process of Cf/ZrB2–SiC at various temperatures was analyzed and discussed. 相似文献
9.
《应用陶瓷进展》2013,112(7):391-395
Cf/ZrC, Cf/SiC and Cf/ZrC–SiC composites were successfully prepared by polymer infiltration and pyrolysis (PIP) using polycarbosilane and a liquid ZrC precursor. The densification process, mechanical properties and microstructures were studied in a view of comparison. After the same total 20 PIP cycles, the Cf/ZrC, Cf/SiC and Cf/ZrC–SiC composites had flexural strengths of 50.1±5.3, 285.7±22.6, 141.5±13.1?MPa respectively; elastic moduli of 7.8±0.9, 57.1±3.2 and 45.1±2.6?GPa respectively; and fracture toughness of 2.5±0.2, 10.4±0.9 and 10.9±1.1?MPa m1/2 respectively. With the introduction of high modulus SiC phase into the ZrC matrix, the densification and modulus of the matrix were improved; as a result, the Cf/ZrC–SiC composite showed higher mechanical properties compared to Cf/ZrC. 相似文献
10.
《应用陶瓷进展》2013,112(6):366-373
AbstractTwo dimensional C/C–ZrB2–ZrC–SiC composites were fabricated through precursor infiltration and pyrolysis process using a mixture of polycarbosilane and ZrB2 precursor and ZrC precursor as the impregnant. The microstructures, mechanical properties and ablation properties of the composites were investigated. The results showed that the homogeneity of the composite improved on using novel precursors that can dissolve with polycarbosilane through the formation of nanocomposite matrix. The flexural strength and fracture toughness first increased and then decreased on increasing the pyrocarbon content in the composite. Compared with the C/C–SiC composite, the ablation resistance of C/C–ZrB2–ZrC–SiC composite was greatly enhanced. The mass loss rate and linear recession rate exposed to the plasma torch were 1?7 mg/s and 1?8 μm/s, respectively. The formation of a ZrO2–SiO2 glassy layer on the surface significantly contributed to the excellent ablative property of the composite. 相似文献
11.
Qinggang Li Shaoming Dong Ping He Haijun Zhou Zhen Wang Jinshan Yang Bin Wu Jianbao Hu 《Ceramics International》2012,38(7):6041-6045
Two-dimensional Cf/ZrC–SiC composites were fabricated through mold-pressing and polymer infiltration and pyrolysis (PIP) using T700SC plain weave fiber fabrics as reinforcements with ZrC precursor and polycarbosilane. The mechanical properties and microstructures of the composites with 34, 45, and 56% fiber fraction were investigated. All composites showed a typical non-brittle fracture behavior and a large amount of pulled-out fibers were observed on the fracture surface. The bending strength and elastic modulus of the composite with 56 vol% fiber fraction increased up to 582 ± 80 MPa and 167 ± 25 GPa, with increasing fiber fraction. The mass loss and linear recession rate of the composites during the oxy-propane torch test were 0.008 g/s and ?0.003 mm/s, respectively. The formation of a ZrSiO4 melt on the surface of the composite significantly contributed to the excellent ablative property of the 2D Cf/ZrC–SiC composites. 相似文献
12.
Two series of C/C–SiC composites were fabricated via precursor infiltration pyrolysis (PIP) and chemical vapor infiltration (CVI) using porous C/C composites with different original densities as preforms, respectively. The tribological characteristics of C/C–SiC braking composites were investigated by means of MM-1000 type of friction testing machine. The friction and wear behaviors of the two series of composites were compared and the factors that influence the friction and wear properties of C/C–SiC composites were discussed. Results show that the friction and wear properties relate close-knit to the content of SiC and porosity. As the original preform density increasing, the content of SiC and porosity decrease, and then the friction coefficient increases obviously, the braking time and the wear rate both decrease. Preparation techniques play an important role in the tribological properties of C/C–SiC composites. Compared with PIP process, the samples from CVI have a little higher friction coefficient, shorter braking time and higher wear rate. 相似文献
13.
《Ceramics International》2015,41(6):7387-7393
The aim of this study is to evaluate the influence of hexagonal boron nitride (hBN) addition on the tribological behavior of B4C-based ceramic composites under distilled water lubrication. Water-lubricated sliding tests of hot-pressed B4C–hBN ceramic composites with different hBN amounts against pure B4C ceramic were carried out on a pin-disc type wear apparatus. It was found that the addition of hBN into B4C ceramic matrix resulted in a severe decrease of the friction coefficient from 0.373 for B4C/B4C sliding pair to 0.005 for B4C–20 wt% hBN/B4C sliding pair. A B2O3 tribochemical film formed on the worn surface of the B4C–hBN specimen protected both B4C–hBN and B4C and facilitated the frictional surfaces to smooth. Therefore, the tribological behaviors of the pairs were significantly improved. The formation process of the film and its antifriction mechanism are discussed. 相似文献
14.
《Journal of the European Ceramic Society》2019,39(4):780-787
The microstructure and elevated temperature mechanical properties of continuous carbon fibre reinforced ZrC and TaC composites were investigated. Silicon carbide was added to both compositions to aid sintering during hot pressing. Fibres were homogeneously distributed and no fibre degradation was observed at the interface with the ceramic matrix even after testing at 2100 °C. The flexural strength increased from 260 to 300 MPa at room temperature to ∼450 MPa at 1500 °C, which was attributed to stress relaxation. At 1800 °C, the strength decreased to ∼410 MPa for both samples. At 2100 °C plastic deformation resulted in lower strength at the proportional limit (210–320 MPa), but relatively high ultimate strength (370–440 MPa). The sample containing ZrC had a lower ultimate strength, but higher failure strain at 2100 °C due to the weak fibre/matrix interface that resulted in fibre-dominated composite behaviour. 相似文献
15.
《Ceramics International》2015,41(7):8488-8493
Cf/ZrC–SiC composites were fabricated by melt infiltration at 1800 °C using Zr–8.8Si alloy and carbon felt preforms. Microstructural analysis showed the formation of both ZrC and SiC phases in the matrix, in which ZrC acted as a main composition of the resulting composites. The results showed that carbon matrix reacted preferentially with Si of Zr–8.8Si alloy, which caused the formation of SiC first and then ZrC. The designed carbon coating by pyrolysis prevented the severe reaction between fibers and the melt. The composites could be more dense and uniform with the bending strength of 53.3 MPa, when preforms had a high open porosity (47.2%) with small size pores (10–40 μm). 相似文献
16.
《Ceramics International》2015,41(6):7677-7686
Ablation behavior of ZrB2–SiC protective coating for carbon/carbon composites during oxyacetylene flame test at 2500 °C was investigated by analyzing the microstructure differentiation caused by the increasing intensity of ablation from the border to the center of the surface. After ablation, a continuous SiO2 scale, a porous SiO2 layer inlaid with fine ZrO2 nuclei, and a continuous ZrO2 scale respectively emerged in the border region, the transitional region, and the center region. In order to investigate the ablation microstructure in the initial stage, the sub-layer microstructure was characterized and found to be mainly formed by coral-like structures of ZrO2, which showed huge difference with the continuous structure of ZrO2 on the surface layer. A kinetic model concerning the thickness change induced by volatilization and oxidation during ablation was built to explain the different growth mechanisms of the continuous ZrO2 scale and the coral-like ZrO2 structure. 相似文献
17.
《Ceramics International》2017,43(3):3439-3442
C/ZrC-SiC composites with a density of 3.09 g/cm3 and a porosity of 4.8% were prepared by reactive melt infiltration and vapour silicon infiltration. The flexural strength and modulus were 235 MPa and 18.3 GPa, respectively, and the fracture toughness was 7.0 MPa m1/2. The formation of SiC and ZrSi2 during vapour silicon infiltration, at the residual cracks and pores in the C/ZrC, enhanced the interface strength and its mechanical properties. The high flexural strength (223 MPa, c. 95% of the original value) after oxidation at 1600 °C for 10 min indicated the excellent oxidation resistance of the composites after vapour silicon infiltration. The mass loss and linear recession rate of the composites were 0.0071 g/s and 0.0047 mm/s, respectively and a fine ablation morphology was obtained. 相似文献
18.
《Ceramics International》2016,42(11):12756-12762
Three-dimensional (3D) Cf/ZrC–SiC composites were successfully prepared by the polymer infiltration and pyrolysis (PIP) process using polycarbosilane (PCS) and a novel ZrC precursor. The effects of PyC interphase of different thicknesses on the mechanical and ablation properties were evaluated. The results indicate that the Cf/ZrC–SiC composites without and with a thin PyC interlayer of 0.15 µm possess much poor flexural strength and fracture toughness. The flexural strength grows with the increase of PyC layer thickness from 0.3 to 1.2 µm. However, the strength starts to decrease with the further increase of the PyC coating thickness to 2.2 µm. The highest flexural strength of 272.3±29.0 MPa and fracture toughness of 10.4±0.7 MPa m1/2 were achieved for the composites with a 1.2 µm thick PyC coating. Moreover, the use of thicker PyC layer deteriorates the ablation properties of the Cf/ZrC–SiC composites slightly and the ZrO2 scale acts as an anti-ablation component during the testing. 相似文献
19.
《Ceramics International》2019,45(16):20414-20426
C/C–ZrC–SiC composites reinforced by SiC nanowire (SiCnw)/pyrocarbon (PyC) core-shell networks were prepared by a multistep method of chemical liquid-vapor deposition (CLVD). The microstructure, mechanical property and ablation resistance were researched. The investigations presented that the PyC was deposited on the SiC nanowires, and the micro-scale core-shell structures were produced. Moreover, these micro-scale structures not only connected with the fibers and matrices, but also filled the pores in the composites. In contrast with C/C–ZrC–SiC composites, the flexural modulus and strength of SiCnw/PyC-C/C–ZrC–SiC composites increased by 36.91% and 44.53%, and the fracture mode was changed from the brittle to pseudo-plastic fracture. After the oxyacetylene torch ablation at two temperatures for 90s, the composites strengthened by SiCnw/PyC core-shell possessed a better resistant ablation. At ablation temperature of 2300 °C, the mass loss rate and linear reduction rate of the composites with core-shell networks decreased by 66.18% and 57.55% in contrast with the non-reinforced composites, and declined by 56.46% and 57.48% at ablation temperature of 3000 °C. The obvious decrease of ablation rates was ascribed to the dense microstructure, the small coefficient of thermal expansion (CTE), the good thermal conductivity, and the resistant ablation roles of SiCnw/PyC core-shell systems. 相似文献