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1.
SiC–ZrC ablation resistance coating was prepared on the surface of carbon fiber reinforced carbon (C/C) composites by simple pack cementation combined with low-cost slurry infiltration method. The results showed that SiC–ZrC coating could effectively protect C/C composites from ablation for 45 s at 3723 K under oxyacetylene torch. The mass and linear ablation rates (0.038 ± 0.01 mg/(s cm2) and 2.42 ± 0.15 μm/s) were largely reduced compared with that of uncoated C/C composites (0.530 ± 0.01 mg/(s cm2) and 1.75 ± 0.15 μm/s) after ablation for 20 s. The good ablation protective ability of SiC–ZrC coating is mainly attributed to the volatilization of SiO2 and the formation of ZrO2. 相似文献
2.
Xiyuan Yao Hejun Li Yulei Zhang Kezhi Li Qiangang Fu Han Peng 《Journal of Thermal Spray Technology》2013,22(4):531-537
In order to improve the ablation resistance of C/C composites, ZrB2-based coating was prepared by supersonic atmosphere plasma spraying for SiC-coated C/C composites. The phase composition, microstructure, and anti-ablation property of the coating were investigated. Results show that the supersonic atmosphere plasma spraying is an effective method to prepare a dense ZrB2-based coating. The coating largely improves the ablation resistance of C/C composites. The linear ablation rate is 0.17 μm/s after ablation for 60 s in oxyacetylene torch. In ablation center, the ablation performance is determined by complicated mechanical denudation and chemical erosion. The formation of ZrO2 during ablation can partly prevent the diffusion of oxygen, which contributes to the good ablation resistance of ZrB2-based coating. In transition zone, the generation of SiO2 prevents inner coating from ablation and the chemical erosion becomes the leading mechanism. 相似文献
3.
Xue-Tao Shen Ke-Zhi Li He-Jun Li Qian-Gang Fu Shu-Ping Li Fei Deng 《Corrosion Science》2011,(1):105-112
Ablation of zirconium carbide (ZrC) modified carbon/carbon (C/C) composites was tested by an oxyacetylene torch. The formation of zirconia from the oxidation of ZrC improves the ablation resistance of the C/C composites because of the evaporation at elevated temperature, which absorbs heat from the flame and reduces the erosive attack to carbon. Zirconia also acts as an accelerator for carbon oxidation as it reacts with carbon during the ablation, increasing the mechanical breakage rate of the fibres. However, the effect of mechanical breakage is inferior in the ablation of the composites. The heterogeneous reactions control the ablation of the composites. 相似文献
4.
Single and cyclic ablations under oxyacetylene torch with 2380 ± 10% kW/m2 heat flux were performed to evaluate the effect of ablation products on the ablation resistance of carbon/carbon – silicon carbide (C/C–SiC) composites separately. As a result of the accumulation of noncrystalline SiO2 enwrapped SiC, ablation resistance of prepared composites was enhanced with time prolonging under single ablation while it was improved more significantly under cyclic ablation. The ablation products played several key roles during ablation: decreasing surface temperature, acting a barrier to oxidizing species attack and conglutinating defective ablated carbon fibers. 相似文献
5.
Microstructure and properties of W-ZrC composites prepared by the displacive compensation of porosity (DCP) method 总被引:1,自引:0,他引:1
Shouming Zhang Song WangWei Li Yulin ZhuZhaohui Chen 《Journal of Alloys and Compounds》2011,509(33):8327-8332
Tungsten-zirconium carbide composites were fabricated at different temperatures by the displacive compensation of porosity (DCP) method, the microstructure, mechanical properties, and ablation resistance were investigated. It was found that no WC phase was left in the composites prepared at 1400 °C, and a few residual W2C particles were surrounded in W product. Microstructure analyses revealed that zirconium atoms diffused into tungsten carbide to form ZrC and W2Zr besides carbon diffused into the Zr2Cu melt. Composites fabricated at 1400 °C had a flexural strength of 356.7 ± 15.2 MPa, an elastic modulus of 193.7 ± 9.8 GPa, a fracture toughness of 7.0 ± 0.7 MPa m1/2, and a hardness of 13.6 ± 0.7 GPa. After ablated by an oxyacetylene flame for 30 s, the higher temperature prepared composites had a better ablation resistance, the linear ablation rate was 0.0033 ± 0.0004 mm/s, and the mass ablation rate was 0.0012 ± 0.0001 g/s. 相似文献
6.
Carbon/carbon composites modified by ZrB2–ZrC–SiC particles (C/C–Z–SiC), C/C–Z and C/C were ablated by oxyacetylene torch using two different heat fluxes to investigate the effect of doped ceramic particles. Results indicated that C/C–Z–SiC had the best ablation property in heat flux of 2.38 MW/m2 whereas their ablation rates increased fastest when heat flux rising from 2.38 to 4.18 MW/m2. C/C composites had the poorest ablation property in the lower heat flux and their ablation rates increased slowest. Thermal mismatch of Z, SiC and C and evaporation of SiO2 induced the various ablation behavior. 相似文献
7.
采用大气等离子喷涂技术(APS)在C/C复合材料表面制备了mullite/ZrB2-MoSi2双层抗烧蚀涂层。借助XRD、SEM、EDS等分析手段对涂层的组织结构进行研究;基于氧丙烯焰烧蚀试验考察ZrB2-MoSi2/mullite复合涂层对C/C复合材料高温耐烧蚀性能的影响。结果表明,在1700 °C和1800 °C的氧丙烯焰下烧蚀60 s,ZrB2-MoSi2/mullite涂层试样的质量烧蚀率分别为3.49×10-3 g/s与3.77×10-3 g/s。其与单层ZrB2-MoSi2涂层试样相比,ZrB2-MoSi2/mullite涂层试样展现了出色的抗烧蚀性能。烧蚀过程中形成的硅酸盐玻璃可以作为热障层而减少氧气的进一步渗透,并且还具有自我封填缺陷的能力,使ZrB2-MoSi2/mullite涂层表现较好的抗烧蚀性。 相似文献
8.
采用等离子喷涂工艺在C/SiC基体材料表面制备了较为致密的W粘结层和ZrC耐烧蚀涂层,利用氧乙炔火焰测试其抗烧蚀性能。结果表明:涂层具有良好的抗烧蚀性能。经烧蚀距离30 mm的氧乙炔烧蚀300 s后,涂层的质量烧蚀率为1.7×10~(-3)g·s~(-1),仅为无涂层试样的68%;线烧蚀率为4.0×10~(-4)mm·s~(-1),仅为无涂层试样的30%。随着烧蚀距离的减小,涂层的质量烧蚀率不断增大,线烧蚀率不断减小。试样表面温度梯度导致涂层存在3种典型烧蚀形貌,中心致密区,过渡区以及边缘疏松区。温度较高的中心区氧化产物为WO_3,其发生熔融并填充涂层内部孔隙和裂纹,形成致密层,且与ZrO_2所产生的协同效应有效降低了机械剥蚀几率,烧蚀以热化学烧蚀为主;温度较低的边缘区烧蚀产物未发生熔融且呈现疏松状,烧蚀主要表现为热化学烧蚀和机械剥蚀。 相似文献
9.
A way to improve the ablation properties of the C/SiC composites in an oxyacetylene torch environment was investigated by the precursor infiltration and pyrolysis route using three organic precursors (zirconium butoxide, polycarbosilane, and divinylbenzene). The ceramic matrix derived from the precursors at 1200 °C was mainly a mixture of SiC, ZrO2, and C. After annealing at 1600 °C for 1 h, ZrO2 partly transformed to ZrC because of the carbothermic reductions and completely transformed to ZrC at 1800 °C in 1 h. The mechanical properties of the composites decreased with increasing temperature, while the ablation resistance increased due to the increasing content of ZrC. Compared with C/SiC composites, the ablation resistance of the C/Zr-O-Si-C composites overwhelms because of the oxide films which formed on the ablation surfaces. And, the films were composed of two layers: the porous surface layer (the mixture of ZrO2 and SiO2) and the dense underlayer (SiO2). 相似文献
10.
Oxidation and ablation resistance of ZrB2–SiC–Si/B-modified SiC coating for carbon/carbon composites
ZrB2–SiC–Si/B-modified SiC coating was prepared on the surface of carbon/carbon (C/C) composites by two-step pack cementation. The coating could efficiently provide protection for C/C composites from oxidation and ablation. The improvement of oxidation resistance was attributed to the self-sealing property of the multilayer coating. A dense glassy oxide layer could afford the high temperature up to 2573 K and efficiently protect C/C composites from ablation. 相似文献
11.
Lanthanum erbium carbide, La0.5Er0.5C2, a salt-like carbide with a cubic fluorite phase structure, has been produced from 13C, allowing carbon diffusion rate to be determined using 12C. Carbon in salt-like carbides exhibits significant ionicity, and a high carbon diffusion rate would enable a new class of
high temperature fuel cells based on carbon-ion transport. The complete lack of carbon diffusion data for salt-like carbides
is the motivation for this work. The carbon diffusion rate in La0.5Er0.5C2 has now been determined to be 2.0 ± 0.8 × 10−13 cm2/s at 850 °C, increasing to 1.8 ± 0.8 × 10−11 cm2/s at 1150 °C, with an activation energy of about 95 kJ/mole. These diffusion rates are too low for a carbon-ion fuel cell,
but a number of other salt-like carbides exist. Be2C, in particular, is a salt-like carbide with an antifluorite structure, and should have higher carbon-ion diffusion than
cubic La0.5Er0.5C2 due to the unoccupied octahedral sites in the antifluorite structure, but Be2C presents special difficulties due to the toxic nature of its hydrolysis products. 相似文献
12.
The effect of SiC/ZrC weight ratio on the mechanical and ablation properties of carbon/carbon composites modified by SiC nanowires reinforced SiC–ZrC ceramics (C/C–SiC–ZrC) was studied. Results showed that C/C–SiC–ZrC composites with a SiC/ZrC ratio of 1:1.5 exhibited good mechanical and ablation properties. The flexural strength and modulus were 201 ± 20 MPa and 18 ± 1 GPa, respectively. After ablation for 120 s, the linear and the mass ablation rate were 0.012 mm/s and 0.0019 g/s. The good performance is attributed to a higher density, the reinforcing effect of SiC nanowires and the proper SiC/ZrC ratio. 相似文献
13.
Continuous, uniform Hf(Ta)C coating was co-deposited on carbon/carbon composites by chemical vapor deposition. The phase composition, microstructure and ablation properties of the Hf(Ta)C coating are investigated. Results show that the as-prepared coating is a biphasic coating consisting of HfC and HfTaC2. The particle-stacked structure is effective to produce a crack free Hf(Ta)C coating and good adhesion between the coating and C/C composites. The Hf(Ta)C coating can effectively protect C/C composites from ablation. After 60 s ablation, the mass and linear ablation rates of coated sample are 0.01 ± 0.02 mg cm−2 s−1 and 0.46 ± 0.02 μm s−1, respectively. 相似文献
14.
Can Sun He-jun Li Qian-gang Fu Hai-liang Li Yong-jie Wang Heng Wu 《Journal of Thermal Spray Technology》2013,22(4):525-530
To protect carbon/carbon (C/C) composites against oxidation, ZrSiO4 oxidation protective coating was prepared on SiC-coated C/C composites by supersonic plasma spraying. X-ray diffraction and scanning electron microscopy were used to analyze the phase and microstructure of the coating. The results show that the as-prepared ZrSiO4 coating is continuous and well bonded with the SiC inner layer without penetrating crack, which exhibits good oxidation-resistant properties. After oxidation at 1773 K in air for 97 h and nine thermal shock cycles between 1773 K and room temperature, the weight loss of the coated C/C composites was only 0.08%. The excellent oxidation-resistant properties of the coating were attributed to its dense structure and the formation of the stable ZrO2-SiO2 glassy mixture on the surface of ZrSiO4 coating. 相似文献
15.
Oxidation protection of C/SiC coated carbon/carbon composites with Si–Mo coating at high temperature
To protect carbon/carbon (C/C) composites against oxidation, a Si–Mo coating was prepared on C/SiC-coated C/C composites by a simple slurry method. The microstructure of the coating was characterized by X-ray diffraction, scanning electron microscopy and Raman spectra. Results showed that the coating was mainly composed of SiC, MoSi2 and Si. It could protect C/C composites from oxidation at 1873 K in air for 300 h and withstand 13 thermal cycles between room temperature and 1873 K. The excellent oxidation and thermal shock resistance of the coating was attributed to the formation of dense SiO2 glass at high temperature. The volatilization of MoO3 and SiO2 at 1873 K was the main reason of the weight loss of the coated C/C composites. 相似文献
16.
Lingyan Kong Bin Lu Xinyu Cui Hao Du Tiefan Li Tianying Xiong 《Journal of Thermal Spray Technology》2010,19(3):650-656
This paper reports the oxidation behavior of TiAl3/Al composite coating deposited by cold spray. The substrate alloy was orthorhombic-Ti-22Al-26Nb (at.%). The oxidation kinetics
of the coating was tested at 650, 800, and 950 °C, respectively. The parabolic rate constant for the coating oxidized at 650 °C
was k
p = 7.2 × 10−2 mg·cm−2·h−1/2 for the tested 1200 h. For the coating oxidized at 800 °C, the oxidation kinetics could be separated into two stages with
k
p value of 39.8 × 10−2 mg·cm−2·h−1/2 for the initial 910 h and 17.7 × 10−2 mg·cm−2·h−1/2 for the stage thereafter. For the coating oxidized at 950 °C, the oxidation kinetics can be separated into three stages with
k
p of 136.9 × 10−2 mg·cm−2·h−1/2 in the first 100 h, followed by 26.9 × 10−2 mg·cm−2·h−1/2 from 100 to 310 h, and 11.8 × 10−2 mg·cm−2·h−1/2 from 310 to 1098 h. XRD, SEM, and EPMA were used to study the microstructure of the coating. The results indicated that the
oxidation took place throughout the entire coating instead of only at the surface. The aluminum phase in the composite coating
was soon oxidized to Al2O3 in all tested cases. The aluminum in TiAl3 phase was depleted gradually and oxidized to Al2O3 along with the degradation of TiAl3 to TiAl2 and TiAl as the temperature increased and time proceeded. AlTi2N was also a typical oxidation product at temperature higher than 800 °C. The experimental results also indicated that the
protection of the coating was attributed greatly to the interlayer formed between the coating and the substrate. 相似文献
17.
以无纬布/网胎0°/90°叠层穿刺预制体为增强体,采用化学气相渗(Chemical vapor infiltration,CVI)、树脂浸渍碳化(Polymer infiltration carbonization,PIC)与反应熔渗(Reactive melt infiltration,RMI)复合工艺制备穿刺C/C-SiC复合材料,研究其微观组织及在C2H2-O2焰中的烧蚀行为。结果表明:无纬布、穿刺纤维束由CVI+PIC制备的碳基体填充而形成致密C/C区域,RMI生成的SiC主要位于网胎层中,其含量37.3wt%。复合材料表面因过量硅化而形成了SiC富集层。烧蚀距离20mm、O2:C2H2=2:1时,烧蚀600s后材料X-Y、Z向线烧蚀率分别为:0.8×10-4 mm/s、3.6×10-4 mm/s,比PIP工艺制备C/C-SiC材料烧蚀率小一个数量级。烧蚀面SiC富集层保护及被动氧化作用是材料具有优异抗氧化烧蚀性能的主要原因。随烧蚀距离由20mm向10mm减小,复合材料烧蚀率先缓慢变化后快速增大,烧蚀率快速增长阶段复合材料发生主动氧化烧蚀。 相似文献
18.
Ablation properties and thermal conductivity of carbon/carbon (C/C) composites containing hafnium carbide (HfC) were investigated. The C/C composites containing 6.5 wt.% HfC exhibit the best thermal conductivity and ablation resistance. The improvement of the thermal conductivity is attributed to the increased phonon–defect interaction produced by the thermal motion of CO released from the reaction of carbon and ZrO2. High thermal conductivity of the composites can slow down the ablation of carbon. When the HfC mass fraction is greater than 6.5 wt.%, cracks generated act as diffusion channels for an oxidizing atmosphere and thus accelerate the ablation of the composites. 相似文献
19.
用自制的氧乙炔烧蚀装置对ZrCp/W复合材料烧蚀性能进行了研究。结果表明:复合材料的质量烧蚀率和线烧蚀率由低到高的排列顺序为 40%ZrCp(体积分数,下同)/W<30%ZrCp/W<W;钨中加入ZrC颗粒明显提高了钨的抗烧蚀性能,而且 ZrC颗粒含量越高,材料抗烧蚀性能越好。并用多波长高温计对烧蚀表面温度进行在线测试。复合材料烧蚀机理是W,ZrC的氧化烧蚀。 相似文献
20.
Cui Hu Yaran Niu Hong Li Musu Ren Xuebin Zheng Jinliang Sun 《Journal of Thermal Spray Technology》2012,21(1):16-22
SiC coatings for carbon/carbon (C/C) composites have been prepared by the combination process of vacuum plasma spraying technology
and heat treatment. The SiC coatings were formed by the reaction of C/C substrates with as-sprayed silicon coatings deposited
by vacuum plasma spraying. The preparation temperature and the thickness of original silicon coatings have great influence
on the microstructure and the thickness of the synthesized SiC coatings. The results indicated that a continuous and dense
SiC coating has been produced on the surface of C/C substrates. The SiC coatings prepared at 2073 K with the silicon coatings
of 230 μm thickness, exhibited a low mass loss of 2.56% in the plasma jet with temperature about 2473 K and duration of 420 s
in atmosphere. The present results implied that vacuum plasma spraying technology combined with heat treatment was an acceptable
method for synthesis of protective SiC coatings for C/C composites. 相似文献