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Chinese Journal of Aeronautics 2023年第9期36卷 426-436页

作者： Jiaping ZHANG Yuepeng XIN Running WANG Qiangang FU Shaanxi Key Laboratory of Fiber Reinforced Light Composite Materials Northwestern Polytechnical UniversityXi’an 710072China

C/C-SiC-HfC composites were fabricated by using Precursor Infiltration and Pyrolysis(PIP) combined with Gaseous Silicon Infiltration(GSI) process. Different GSI temperatures(1900 ℃ and 2100 ℃) were selected. The combination of PIP and GSI could significantly reduce the preparation time of the composites. The morphology displaying a rich-Si layer was formed on the surface of the composites prepared at GSI 2100 ℃. ablation performance of the composites was investigated by oxyacetylene torch. The results showed that after ablation for 120 s, compared to the composites prepared by PIP + 1900 ℃ GSI, the linear and mass ablation rates of the composites fabricated by PIP + 2100 ℃ GSI were decreased from 8.05 μm/s to 5.06 μm/s and from 1.61 mg/s to 1.03 mg/s, respectively. The coverage of the rich-Si surface layer promoted the generation of more SiO_(2) during ablation, which not only benefited for decreasing the surface temperature but also contributed to the formation of H-Si-O glass and the HfO_(2) skeleton, thus better resisting the denudation of the oxyacetylene torch.

关键词： ablation C/C composites GSI HfC-SiC PIP

ablation characteristics of mosaic structure ZrC-SiC coatings on low-density, porous C/C composites

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Journal of Materials Science & Technology 2019年第12期35卷 2785-2798页

作者： Yonglong Xu Wei Sun Xiang Xiong Fuqun Liu Xingang Luan State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China China Academy of Launch Vehicle Technology Beijing 100076China Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi'an 710072China

Mosaic structure ZrC-SiC coatings were fabricated on low-density, porous C/C composites via thermal evaporation and an in-situ method. ZrC was packed in a typical lamellar mode, and the mosaic structure was formed by the deposition of Zr and Si atoms on the shallow surface of the porous C/C *** analysis showed that the defects in the coatings originate from the boundary between the ZrC and holes created by the consumption of SiC at 2500℃. After ablation for 200 s at 3000℃, a dense ZrO2 layer formed on the coating surface, and the defects were sealed owing to the continuous supply of ablative components. The mass and line ablation rates of the Zr C-SiC coatings were-0.46 ± 0.15 mg cm^-2·s^-1 and-1.00± 0.04 μm s^-1, respectively.

关键词： ZrC SiC Coating Mosaic structure Porous C/C composites ablation

ablation and geometry change study of solid armature in a railgun

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Chinese Physics B 2013年第8期22卷 410-415页

作者：张亚东阮江军胡元潮龚若涵文武 School of Electrical Engineering Wuhan University

Armature plays an important role in the electromagnetic launch process. Due to the skin effect, the current density distribution is neither uniform on the rail, nor on the armature. High current density centralization in one part could lead to a partial high temperature and make the armature material melt down and be ablated, especially at low velocity. In this paper we try to change the geometry of a Cshaped armature to improve the current density distribution and reduce the ablation. Four variants of C-shaped armatures are designed to study the specific features, including a conventional C-shaped armature （CCA）, a rounded leading edge C-shaped armature （LCA）, a rounded trailing edge C-shaped armature （TCA）, and a rounded incorporate edge C-shaped armature （ICA）. A novel low-speed experiment is constructed and tested. The armatures are ablated and recovered to compare the improved effects. Then finite element simulations according to the experimental results are performed to further analyze the experimental results. It is proved that the current density and hence the temperature distribution can be immensely improved by simply changing the armature geometry. LCA and ICA show that the erosion is more uniform on the contact surface due to the rounded leading edge. The curved trailing edge could improve the uniformity of the current on the interface. ICA which combinesthe effects of LCA and TCA is the best option in the four armatures. How much the leading edge and the trailing edge should be curved involves the geometry of CCA and the posture of the interface on the rail. A saddle shape is a good option to improve the current density and temperature distribution in the throat. Erosion mechanism is analyzed finally. The experiments and simulations support the erosion and transition mechanism. A detailed description of the experiments and simulations is also presented in this paper.

关键词： railgun ablation friction geometric modeling

ablation-resistant Ir/Re coating on C/C composites at ultra-high temperatures

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Rare Metals 2022年第1期41卷 199-208页

作者： Hong Zhang Li-An Zhu Shu-Xin Bai Yi-Cong Ye Department of Materials Science and Engineering College of Aerospace Science and EngineeringNational University of Defense TechnologyChangsha 410073China

An iridium/rhenium(Ir/Re)double-layer coating was prepared on carbon/carbon(C/C)composites by chemical vapor deposition(CVD)and *** morphologies and bond strengths of the coatings on the C/C substrate were *** ablation resistance of the Ir/Re coating was studied at 1800℃in an oxyacetylene torch flame for 300 *** results show that Re interlayer increases the bond strength between Ir coating and C/C substrate by over 100%.During entire hightemperature ablation process,Ir/Re coating keeps intact without any signs of ablation *** coating gets smoother and the grain size becomes larger after ablation,with the preferred orientation changing from h311i to h220i:Although some voids are observed along the grain boundaries of the as-ablated Ir coating,Ir/Re coating keeps intact on C/C *** study indicates that Ir/Re coating can provide good ablation resistance up to 1800℃for C/C composites,especially for the continuous ablation applications.

关键词： Iridium Rhenium Carbon/carbon(C/C) Interlayer ablation

ablation of C/SiC-HfC composite prepared by precursor infiltration and pyrolysis in plasma wind tunnel

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Journal of Advanced Ceramics 2020年第3期9卷 393-402页

作者： Liuyang DUAN Lei LUO Liping LIU Yiguang WANG Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi'an 710072China Beijing Institute of Long March Aerospace Vehicles Beijing 100076China Ultrahigh Speed Aerodynamics Research Institute China Aerodynamics Research and Development CenterMianyang 621000China Institute of Advanced Structure Technology Bejing Institute of TechnologyHaidian DistrictBeijing 100081China

Carbon fiber reinforced silicon carbide-hafnium carbide(C/SiC-HfC)composite was prepared by precursor infiltration and pyrolysis ***,ablation behavior of C/SiC-HfC was evaluated in plasma wind *** was found that oxide layer formed during ablation significantly influenced the surface *** of dense HfO2 SiO2 layer under low heat flux led to stable surface ***(SiO2)on the surface was gradually consumed when heat flux increased,resulting in conversion of HfO2-SiO2 on the surface to *** HfO2 with high catalytic cofficient absorbed more energy,causing gradual increase in the surface *** oxide layer was destroyed at high heat flux and high stagnation point *** carbon fiber lost the protection of HfO2-SiO2 layer,it burned immediately,leading to surface temperature jump.

关键词： C/SiC-HfC composite precursor infilration and pyrolysis ablation plasma wind tunnel

ablation mechanism of TaC coating fabricated by chemical vapor deposition on carbon-carbon composites

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中国有色金属学会会刊：英文版 2009年第S3期19卷 689-695页

作者：李国栋熊翔黄可龙 State Key Laboratory of Powder Metallurgy Central South University School of Chemistry and Chemical Engineering Central South University

ablation characteristics and mechanism at high temperature for TaC coatings on carbon-carbon composites were investigated by ablation experiments with low power laser and oxyacetylene flame. The results show that the TaC coating is decomposed at the initial stage of laser ablation in atmosphere, and free carbon diffused to the surface, then oxidized to the melt including carbon, oxygen and tantalum. With the increase of ablation time, the melt is oxidized to low valent tantalum-oxide and Ta2O5 is formed finally. During the melt cooling, needle-like crystals of Ta2O5 are precipitated. Between the melt and TaC coating, there exists a diffusion transition layer with thickness of 1-2 μm. The transition layer consists of fine crystals and pores including carbon, oxygen and tantalum. The oxyacetylene flame ablation at 2 300 ℃ results in the rapid oxidation of TaC and formation of protective liquid films of tantalum oxide on the coating surface, where the liquid film can fill up the cracks and cover the coating. In such case, the oxidation mechanism of TaC is converted to the oxygen solution and diffusion control mechanism.

关键词： TaC coating oxidation ablation mechanism carbon-carbon composites

ablation characteristics of insulator under high-temperature gas dual-pulse erosion

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Defence Technology（防务技术） 2022年第10期18卷 1875-1885页

作者： Yang Liu Xiao-cong Li Peng-fei Zhu Kun Xi Northwestern Polytechnical University 710072Xi'anPR China Xi'an Modern Chemistry Research Institute 710065PR China Department of Aerospace Propulsion Technology Science and Technology on CombustionInternal Flow and Thermal-Structure LaboratoryShaanxiPR China

This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperature dual-pulse *** ablation rate of ethylene-propylene-diene monomer(EPDM)insulator was measured after the *** results were analyzed through scanning electron microscopy and microcomputed *** ablation mechanism of the EPDM insulator under the operation conditions of a dual-pulse solid rocket motor was evaluated by analyzing the *** results reveal that the internal flow field of the motor with a soft pulse separation device is *** original charred layer existing on the EPDM insulator surface in the first pulse combustor is the decisive factor affecting the final ablation rate of the dual-pulse motor during the second pulse operation,and the ablation characteristic region is easily formed with the exfoliation of the charred *** ablation rate difference of the insulator increases with gas velocity.

关键词： Dual-pulse solid rocket motor High temperature gas ablation PSD Charred layer

ablation of GaN Using a Femtosecond Laser

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Chinese Physics Letters 2002年第11期19卷 1711-1713页

作者：刘伟民袁述等 DepartmentofPhysics FudanUniversityShanghai200433 SchoolofMaterialsEngineering NanyangTechnologicalUniversityBLKN4NanyangAvenueSingapore6397981

We study the pulsed laser ablation of wurtzite gallium nitride (GaN) films grown on sapphire, using the femtosecond laser beam at a central wavelength of 800nm as the source for the high-speed ablation of GaN films. By measuring the backscattered Raman spectrum of ablated samples, the dependence of the ablation depth on laser fluence with one pulse was obtained. The threshold laser fluence for the ablation of GaN films was determined to be about 0.25J/cm2. Laser ablation depth increases with the increasing laser fluence until the amount of removed material is not further increased. The ablated surface was investigated by an optical surface interference profile meter.

关键词： ablation GaN Using Femtosecond Laser

ablation properties of C/C composites with various needled preforms prepared by isothermal chemical vapor infiltration

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Journal of Central South University of Technology 2007年第1期14卷 13-18页

作者：汤素芳王道岭邓景屹刘文川杨柯 Institute of Metal Research Chinese Academy of Sciences

The ablation properties of C/C composites with four different needled preforms prepared by isothermal chemical vapor infiltration （ICVI）, which are super-thin mat lay-up, 0°/90° weftless fabric lay-up, 0°/45° weftless fabric lay-up and 0°/45° twill fabric lay-up, were quantitatively evaluated by performing the ablation tests with an engine torch. And their ablation discrepancies were analyzed according to the surface characteristic, porosity and thermal diffusivity. The results show that the 0°/45° weftless composite has a fiat eroded surface with no obvious macroscopic pits. Its thickness and mass erosion rates are decreased by about 46.8% and 34.8%, 25.0% and 27.5%, and 17.5% and 19.4% compared with those of the mat, the 0°/90° weftless and the 0°/45° twill composites, respectively. The ablation properties are mainly controlled by the thermo-chemical effect （oxidation）, and a little by the thermo-mechanical effect （mechanical denudation）. The needling fiber bundles play an important role in accelerating the ablation process and resulting in the heterogeneous ablation.

关键词： C/C composites ablation fiber architecture isothermal chemical vapor infiltration thermal diffusivity

ablation and radar-wave transmission performances of the nitride ceramic matrix composites

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Science China(Technological Sciences) 2008年第1期51卷 40-45页

作者： JIANG YongGang ZHANG ChangRui CAO Feng WANG SiQing HU HaiFeng QI GongJin State Key Laboratory of New Ceramic Fibers&Composites College of Aerospace and Materials EngineeringNational University of Defense TechnologyChangsha 410073China

The 2.5 dimensional silica fiber reinforced nitride matrix composites (2.5D SiO2f/Si3N4-BN) were prepared through the preceramic polymer impregnation pyro- lysis (PIP) method. The ablation and radar-wave transparent performances of the composite at high temperature were evaluated under arc jet. The composition and ablation surface microstructures were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the 2.5D SiO2f/Si3N4-BN composites have a linear ablation rate of 0.33 mm/s and high radar-wave trans- parent ratio of 98.6%. The fused layer and the matrix are protected by each other, and no fused layer accumulates on the ablation surface. The nitride composite is a high-temperature ablation resistivity and microwave transparent material.

关键词： silica fibers nitride matrix composites ablation and radar-wave transparent performances