共查询到20条相似文献,搜索用时 12 毫秒
1.
《Ceramics International》2017,43(15):12005-12012
To improve the ablation resistance of SiC coating, HfB2-SiC coating was prepared on SiC-coated carbon/carbon (C/C) composites by in-situ reaction method. Owing to the penetration of coating powders, there is no clear boundary between SiC coating and HfB2-SiC coating. After oxyacetylene ablation for 60 s at heat flux of 2400 kW/m2, the mass ablation rate and linear ablation rate of the coated C/C composites were only 0.147 mg/s and 0.267 µm/s, reduced by 21.8% and 60.0%, respectively, compared with SiC coated C/C composites. The good ablation resistance was attributed to the formation of multiple Hf-Si-O glassy layer including SiO2, HfO2 and HfSiO4. 相似文献
2.
Jian Zhang Yulei Zhang Yanqin Fu Du Hu Jiachen Meng Tao Li 《Journal of the European Ceramic Society》2021,41(3):1769-1778
The thickness of the different HfC coatings from 20 μm to 50 μm were prepared on the surface of carbon/carbon (C/C) composites by low pressure chemical vapor deposition (LPCVD). The microstructure and thermal stress of the coatings after ablation were investigated, as well as the effect of thickness and thermal stress on the ablation resistance of the HfC coating was analyzed. After being ablated at a heat flux of 2.4 MW/m2 for 60 s, the thermal stress gradually increased at first and then rapidly increased with the increasing thickness of coating. The results indicated that the moderate coating thickness can effectively release the thermal stress generated during the ablation process. The 40 μm-thick HfC coating showed the best ablation resistance with the mass ablation rate and line ablation rate were only 0.13 mg/s and 0.09 μm/s, respectively. 相似文献
3.
Jincui Ren Errong Feng Yulei Zhang Jian Zhang Donghai Ding Lu Li 《Ceramics International》2021,47(1):556-566
To amend the oxidation and ablation resistance of C/C composites, HfC-ZrC biphase coating was synthesized by CVD. Influences of deposition temperature and CH4 flow rate on the deposition rate, phase constitution and microstructure of the HfC-ZrC coating were investigated. Ablation behavior and ablation mechanism of the HfC-ZrC coating with different ZrC contents were examined. With the deposition temperature rising, the deposition rate and grain size of the HfC-ZrC coating increased. High flow rate of CH4 was beneficial to improving the deposition rate and reducing the grain size of the HfC-ZrC coating. Moderate ZrC content in the HfC-ZrC coating was conducive to the process of solid solution sintering among HfO2 and ZrO2 grains, leading to generating a continuous and compact oxide layer. The coating with HfC/ZrC mole ratio of 1:1 exhibited superior anti-ablation performance, owing to its flat and compact structure and sufficient solid solution sintering among the oxide grains during ablation. 相似文献
4.
L. Silvestroni A. Vinci S. Failla L. Zoli V. Rubio J. Binner D. Sciti 《Journal of the European Ceramic Society》2019,39(9):2771-2781
A new class of ZrB2 composites reinforced with 40 vol% C short fibers and containing 5 vol% SiC in combination with 5 vol% MoSi2, HfSi2 or WSi2 successfully withstood extreme conditions in a oxyacetylene torch. Different responses to the torch testing were recorded depending on which secondary phase was present; this was primarily a result of the final density which ranged between 83 and 94% of the theoretical value. The temperatures achieved on the surfaces of the samples tested also varied as a function of the residual porosity and ranged from 2080 to 2240 °C. HfSi2 additions offered the best performance and exceeded that of the baseline material that contained only SiC. It is believed that this was due to its ability to promote the elimination of porosity during densification and to the refractory nature of its oxide, HfO2. In contrast, MoSi2 and WSi2 formed highly volatile oxides on the surface, which did not offer better protection than the ZrO2-SiO2 scale that developed in the baseline. 相似文献
5.
Xiaochao Jin Xueling Fan Chunsheng Lu Tiejun Wang 《Journal of the European Ceramic Society》2018,38(1):1-28
Carbon/carbon (C/C) composites are considered as one of the most promising materials in structural applications owing to their excellent mechanical properties at high temperature. However, C/C composites are susceptible to high-temperature oxidation. Matrix modification and coating technology with ultra-high temperature ceramics (UHTCs) have proved to be highly effective to improve the oxidation and ablation resistance of C/C composites. In this paper, recent advances in oxidation and ablation resistance of C/C composites were firstly reviewed, with attention to oxidation and ablation properties of C/C composites coated or modified with UHTCs. Then, several new methods in improving oxidation and ablation resistance were discussed, such as by using nanostructures to toughen UHTCs coatings or carbon matrix and the combination of matrix modification and coating technology. In addition, relevant ablation tests with scaled models were also briefly introduced. Finally, some open problems and future challenges were highlighted in the development and application of these materials. 相似文献
6.
For extending application of TaSi2 in complex coating system, the ablation behavior and thermal protection performance of TaSi2 coating is studied to evaluate its potential applications for anti-ablation protection of C/C composites. TaSi2 coating is prepared by supersonic atmospheric plasma spraying (SAPS) on the surface of SiC coated carbon/carbon (C/C) composites. Phase variation and microstructure are characterized by XRD and SEM, respectively. During the ablation process, the coating is quickly oxidized to SiO2 and Ta2O5 accompanied by a lot of heat consumption. The linear and mass ablation rates are 0.9?µm?s?1 and ??0.4?mg?s?1 after ablation for 80?s, respectively Results show that the prepared coating possesses optimal ablation performance under the heat flux of 2.4?MW/m2. Moreover, the TaSi2 coating and SiC inner coating have good chemical and physical compatibility during the ablation process. Therefore, the excellent performance of TaSi2 coating during the ablation process makes it a candidate for anti-ablation protection for C/C composites. 相似文献
7.
《Ceramics International》2022,48(20):30338-30347
A novel network interlacing ZrC-VC ceramic coating was prepared by a pioneering spillover permeation. With the increase of Zr content in the blind vias, the content of ZrC in the coating and the density of the coating all decrease. The density of the coating on C/C–ZrC–SiC substrate is obviously higher than that on C/C substrate. The linear ablation rate of the novel ceramic coated C/C–ZrC–SiC composites was ?0.06 μm/s with about 20 and 1.56 times reduction than C/C composites and C/C–ZrC–SiC composites respectively. The improved ablation resistance was attributed to a dense honeycomb ZrO2 layer filled with liquid vanadium oxide in the ablation center and the improved thermal radiation. 相似文献
8.
Fei Liu Hejun Li Wei Zhang Xiyuan Yao Qiangang Fu Xinhai He 《Ceramics International》2021,47(11):15030-15038
To improve the ablation resistance of carbon/carbon (C/C) composites, a proportional amount of ZrSi2-CrSi2-Y2O3 mixed particles were deposited on the surface of SiC-coated C/C composites by supersonic air plasma spraying (SAPS) to form a ZrSi2-CrSi2-Y2O3/SiC coating. The microstructure and phase compositions of the coating were studied by SEM, EDS, XRD and its anti-ablation performance was tested by oxyacetylene torch. The experimental results showed that the ZrSi2-CrSi2-Y2O3 outer coating had a dense microstructure without obvious pores and microcracks, and the thickness reached approximately 150 μm. In the process of being eroded and scoured by the oxyacetylene flame, the coating exhibited excellent anti-ablation property, which was attributed to the mosaic microstructure formed by ZrO2 and a Si-O-Cr liquid film on the coating surface. After experiencing an ablation time of 80 s, the linear ablation rate and the mass ablation rate of the coating were -1.0 ± 0.03 μm s-1 and -0.16 ± 0.014 mg s-1, respectively. 相似文献
9.
《Ceramics International》2020,46(13):20742-20750
Novel microwave-absorbing SiOC composite ceramics with dual nanowires (carbon nanowires (CNWs) and SiC nanowires) with high performances were fabricated by using the polymer-derivation method and heat treatment in Ar atmosphere. The introduction of CNWs in the amorphous SiOC ceramics promotes the ceramic crystallization into SiC nanoparticles and SiC nanowires at lower annealing temperatures, which leads to multi-phases and multiple nano heterogeneous interfaces. The distinctive architectures largely increase the interfacial and dipole polarizations of the composite ceramics. The CNWs/SiC/SiOC composite ceramics exhibit excellent microwave-absorption properties in the Ku band (12.4–18 GHz). The minimum reflection coefficient (RC) is -24.5 dB at a thickness of 1.8 mm, while the maximum effective absorption bandwidth (EAB, the corresponding frequency band in which RC is smaller than -10 dB) is 4.8 GHz at a thickness of 1.9 mm, which make the CNWs/SiC/SiOC composite ceramics promising electromagnetic-wave-absorbing materials. 相似文献
10.
Hejun Li Zishan Chen Kezhi Li Qingliang Shen Yanhui Chu Qiangang Fu 《Journal of the European Ceramic Society》2013,33(15-16):2961-2969
To improve the wear resistance of SiC coating on carbon/carbon (C/C) composites, SiC nanowires (SiCNWs) were introduced into the SiC wear resistant coating. The dense SiC nanowire-reinforced SiC coating (SiCNW-SiC coating) was prepared on C/C composites using a two-step method consisting of chemical vapor deposition and pack cementation. The incorporation of SiCNWs improved the fracture toughness of SiC coating, which is an advantage in wear resistance. Wear behavior of the as-prepared coatings was investigated at elevated temperatures. The results show that the wear resistance of SiCNW-SiC coating was improved significantly by introducing SiC nanowires. It is worth noting that the wear rate of SiCNW-SiC coating was an order of magnitude lower than that of the SiC coating without SiCNWs at 800 °C. The wear mechanisms of SiCNW-SiC coating at 800 °C were abrasive wear and delamination. Pullout and breakage of SiC grains resulted in failure of SiC coating without SiCNWs at 800 °C. 相似文献
11.
《Journal of the European Ceramic Society》2022,42(15):6898-6907
TaC coatings with four kinds of crystal structures were prepared on carbon/carbon composites by chemical vapor deposition. The surface morphologies, microstructure transformation, and ablative behaviors of TaC coated C/C specimens were investigated. Results show that the coatings with acicular crystal structure exhibit better ablation resistance with lower ablation rates, especially the needle-piled sample. The bistratal structure composed of dense glass layer and compact TaC layer is beneficial for maintaining the integrity of acicular samples after ablation. But the formation of lamella grains and porous middle layer is the main factor for the damage and even exfoliation of the columnar specimens. 相似文献
12.
《Ceramics International》2017,43(5):4520-4526
In this paper, magnetic porous Ni-modified SiOC(H) ceramic nanocomposites (Ni/SiOC(H)) were successfully prepared via a template-free polymer-derived ceramic route, which involves pyrolysis at 600 °C of nickel-modified allylhydridopolycarbosilane (AHPCS-Ni) precursors synthesized by the reaction of allylhydridopolycarbosilane (AHPCS) with nickel(II)acetylacetonate (Ni(acac)2). The resultant Ni/SiOC(H) nanocomposites are comprised of in-situ formed nanoscaled Ni socialized with small amounts of NiO and nickel silicides embedded in the amorphous SiOC(H) matrix. The materials show ferromagnetic behavior and excellent magnetic properties with the saturation magnetization in the range of 1.71–7.08 emu g−1. Besides, the Ni/SiOC(H) nanocomposites are predominantly mesoporous with a high BET surface area and pore volume in the range of 253–344 and 0.134–0.185 cm3 g−1, respectively. The measured porosity features cause an excellent adsorption capacity towards a template dye acid fuchsin with the adsorption capacity Qt at 10 min of 80.7–85.8 mg g−1 and the Qe at equilibrium of 123.8–129.8 mg g−1. 相似文献
13.
《Ceramics International》2017,43(3):3238-3245
In this study, SiC coating for C/C composites was prepared by pack cementation method at 1773 K, and MoSi2-SiOC-Si3N4 as an outer coating was successfully fabricated on the SiC coated samples by slurry method at 1273 K. The microstructure and phase composition of the coatings were analyzed. Results showed that a porous β-SiC inner coating and a crack-free MoSi2-SiOC-Si3N4 coating are formed. Effect of Si3N4 content on the oxidation resistance of the coated C/C composites at 1773 K in air was also investigated. The weight loss curves revealed that introducing the appropriate proportion of Si3N4 could improve the oxidation resistance of coating. The MoSi2-SiOC/SiC coated C/C sample had an accelerated weight loss after oxidation in air for 20 h. However, the coating containing 45% Si3N4 could protect C/C composition from oxidation for 100 h with a minute weight loss of 0.63%. 相似文献
14.
《Journal of the European Ceramic Society》2022,42(3):877-889
Ablation behaviour of poly(hydridomethylsiloxane) derived open and closed porous structured SiOC ceramic foams was evaluated using oxy-acetylene flame at 1500 °C for various time durations. X-ray diffraction and scanning electron microscopy analyses of ablated SiOC ceramic foams revealed the formation of a thin protective SiO2 layer inhibiting further oxidation. The closed porous structured SiOC ceramic foams exhibited very low mass ablation rate in contrast to open porous structured SiOC ceramic foams owing to the differences in thermal energy dissipation mechanism. The feasibility of the plausible foam reduction reactions pertaining to the ablation mechanism was further investigated by computing the Gibbs energy and HR-TEM analysis. The study corroborated the significance of tailoring the microporous structured SiOC ceramic foams as potential thermal protection material for high temperature applications. 相似文献
15.
《Ceramics International》2016,42(15):16804-16812
A WC-SiC double-layer coating was prepared on C/C composites to improve their anti-ablation property. The WC outer layer was designed to withstand high heat flux by its high mechanical strength, the SiC inner layer could transform into SiO2 to block oxygen by its good anti-oxygen permeability. During ablation process, amounts of SiO2 filled into the pores and cracks of WC outer layer, forming a steadily self-filling and cooling structure. As a result, the mass and linear ablation rates of WC-SiC coated C/C composites were 0.013 mg s−1 cm2 and −1.61 µm/s, respectively. Compared with single SiC coated and single WC coated C/C composites, the linear ablation rates decreased by 46.3% and 27.3%, respectively, indicating that WC-SiC coating has a remarkable effect to resist chemical and mechanical ablation. 相似文献
16.
17.
《Journal of the European Ceramic Society》2022,42(3):830-840
Based on the investigation of ablation behavior and thermal stress of the monolayered ZrC-SiC coatings with different SiC amounts, an alternate coating consisting of 4 sublayers with 10 and 70 vol.% SiC was prepared on SiC-coated carbon/carbon (C/C) composites through plasma spraying technique. Ablation tests were carried out under oxyacetylene torch with a heat flux of 2.38 MW/m2. The alternate coating could offer 90 s ablation shield for C/C composites, providing superior ablation properties than all monolayered coatings. The improved ablation resistance is mostly induced by the fact that the outmost scale with abundant ZrO2 particles was able to better endure the mechanical denudation from the torch. Moreover, due to the indirect contact with torch, the innermost sublayers were placed into relatively mild environment, thereby most of Si-based oxides could be retained and further hinder oxygen transport inward during ablation. 相似文献
18.
SiC coating was deposited on carbon/carbon (C/C) composites by chemical vapor deposition (CVD). The effects of elevated temperatures on tribological performance of SiC coating were investigated. The related microstructure and wear mechanism were analyzed. The results show that the as-deposited SiC coating consists of uniformity of β-SiC phase. The mild abrasive and slight adhesive wear were the main wear mechanisms at room temperature, and the SiC coating presented the maximum friction coefficient and the minimum wear rate. Slight oxidation of debris was occurred when the temperature rose to 300?°C. As the temperature was above 600?°C, dense oxide film formed on the worn surface. The silica tribo-film replaced the mechanical fracture and dominated the frication process. However, the aggravation of oxidation at elevated temperatures was responsible for the decrease of friction coefficient and the deterioration of wear rate. The SiC coating presented the minimum friction coefficient and the maximum wear rate when the temperature was 800?°C. 相似文献
19.
Tao Li Yulei Zhang Yanqin Fu Jia Sun Jie Li 《Journal of the European Ceramic Society》2021,41(10):5046-5055
Carbon/carbon (C/C) composites have a wide application as the thermal structure materials because of their excellent properties at high temperatures. However, C/C composites are easily oxidized in oxygen-containing environment, which limits their potential applications to a great degree. Silicon carbide (SiC) ceramic coating fabricated via pack cementation (PC) was considered as an effective way to protect C/C composites against oxidation. But the mechanical properties of C/C composites were severely damaged due to chemical reaction between the molten silicon and C/C substrate during the preparation of SiC coating by PC. In order to eliminate the siliconization erosion, a pyrolytic carbon (PyC) coating was pre-prepared on C/C composites by the chemical vapor infiltration (CVI) prior to the fabrication of SiC coating. Due to the retardation effect of PyC coating on siliconization erosion, the flexural strength retention of the SiC coated C/C composites with PyC coating increased from 46.27 % to 107.95 % compared with the specimen without PyC coating. Furthermore, the presence of homogeneous and defect-free PyC coating was beneficial to fabricate a compact SiC coating without silicon phase by sufficiently reacting with molten silicon during PC. Therefore, the SiC coated C/C composites with PyC coating had better oxidation resistances under dynamic (between room temperature and 1773 K) and static conditions in air at different temperatures (1773?1973 K). 相似文献
20.
《Ceramics International》2020,46(6):7055-7064
In this work, ablation properties of NbC and NbC-25 mol.% ZrC coating, deposited on SiC-coated C/C composites by supersonic atmospheric plasma spraying, were tested by an oxyacetylene torch. Results showed that, for NbC coating, an unexpected smooth liquid film mostly composed of niobium suboxides (such as NbO2 and NbO), rather than pure Nb2O5, generated during ablation for 45 s. Mechanical erosion resulted from the molten SiO2, and the relatively low viscosity of the outer oxide layer owing to insufficiently high melting point of niobium suboxides were the key factors for the failure mechanism of NbC coating. While NbC–ZrC coating abated for 90 s has a 97.49 and 66.53% decrease of linear and mass ablation rate relative to NbC coating ablated for 45 s, since ZrO2 hindering the evaporation of SiO2 droplets, and more thermal-stable Nb–O–Zr liquid film endow (NbC–ZrC)/SiC/C/C composites with an outstanding anti-ablation property. 相似文献