National Key Laboratory of Advanced Functional Composite Materials Technology

Beijing, China

National Key Laboratory of Advanced Functional Composite Materials Technology

Beijing, China
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Gao D.,Beihang University | Zhang Y.,Beihang University | Xu C.,National Key Laboratory of Advanced Functional Composite Materials Technology | Song Y.,National Key Laboratory of Advanced Functional Composite Materials Technology | Shi X.,National Key Laboratory of Advanced Functional Composite Materials Technology
Corrosion Science | Year: 2011

Ceramics of ZrB2-20vol.% SiC were prepared by hot pressing method, and ozone (O3) was adsorbed on the surface of the ceramics. Then the as-adsorbed ceramics were oxidized in air and the effect of ozone adsorption on the oxidation behaviour of the ceramic composites was analyzed. The experimental results indicate that adsorption of ozone promotes the oxidation of the ceramic composites, especially for the SiC. In addition, more silica glass formed promotes the formation and crystal growth of zircon. © 2010 Elsevier Ltd.


Tian C.,Beihang University | Gao D.,Beihang University | Zhang Y.,Beihang University | Xu C.,National Key Laboratory of Advanced Functional Composite Materials Technology | And 2 more authors.
Corrosion Science | Year: 2011

The oxidation behaviour of ZrB2-based ceramics under low oxygen partial pressure ranged from 0.5 to 1.5kPa was investigated. Low oxygen partial pressure was found to have remarkable effect on phase composition of the surface and the structures of oxide scale. And the thickness and microstructures of oxide scale was characterized by using scanning electron microscopy and X-ray diffraction analysis. The results indicate that the oxidation mechanism of ZrB2-based ceramics changes under low oxygen partial pressure, and the oxidation resistance increases with the reduction of oxygen partial pressure. © 2011 Elsevier Ltd.


Lu Z.,Beihang University | Liu Q.,Beihang University | Han H.,Beihang University | Zhang D.,National Key Laboratory of Advanced Functional Composite Materials Technology
Materials Science and Engineering A | Year: 2013

Two types of porous Si 3N 4 ceramics with different porosity are fabricated by gel casting technique, where the high pure Al 2O 3 and Y 2O 3 are selected as sintering additive. The effective Young's modulus and compression strength are tested by compressive experiments, respectively. The present emphasis is placed on the mechanical characterization of porous Si 3N 4 ceramics by employing finite element (FE) method. Extracting the primary features of bonded networks, the microstructure of real material is reconstructed in the numerical model. For the obtained materials with different porosity, their compressive behaviors are modeled by FE simulation, respectively. Afterwards, the effective Young's modulus and compression strength are calculated from the numerical results. Compared with experiment data, the calculated results provide a sufficient accordance. Moreover, the modeled failure mechanism in microstructure is also verified by experimental observation. Utilizing the present FE model, the influences of grain aspect ratio and properties of grain boundaries on the effective Young's modulus and compression strength are also investigated, which provides an insight into the relationship between microstructure and macro-mechanical properties for porous Si 3N 4 ceramics. © 2012 Elsevier B.V.


Dai J.,Beihang University | Zhang Y.,Beihang University | Gao D.,Beihang University | Song Y.,National Key Laboratory of Advanced Functional Composite Materials Technology | Shi X.,National Key Laboratory of Advanced Functional Composite Materials Technology
Rare Metals | Year: 2011

An exploratory investigation on the oxidation behavior of polymer derived Si-(B)-C-N ceramic in ambient air was conducted in this paper. The amorphous ceramic was oxidized at 1300 °C for 12 h, and the oxidation products were analyzed by employing XRD, FT-IR and TEM. The experimental results indicate that the amorphous Si-(B)-C-N ceramic undergo a rapid oxidation process, and the oxidation products are divided into two parts: amorphous silica and cristobalite phase silica. The formation mechanism of the oxidation products was analyzed on the basis of characterization results and collected DTA curve in ambient air up to 1100 °C. Furthermore, the oxidation mechanism of the amorphous Si-(B)-C-N ceramics was deduced based on analysis results and thermodynamic consideration. © The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg 2011.


Lu Z.,Beihang University | Zhou Y.,Beihang University | Feng Z.,National Key Laboratory of Advanced Functional Composite Materials Technology | Yang Y.,National Key Laboratory of Advanced Functional Composite Materials Technology | Ji G.,National Key Laboratory of Advanced Functional Composite Materials Technology
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2015

To investigate the damage and failure mechanisms of 2.5D woven fabric composites under compression, and verify the effectiveness of the finite element numerical simulation method with a two-scale, progressive damage model, quasi-static compression experiments were conducted on both warp and weft directional specimens to obtain the corresponding stress-strain curves. And the initial elastic modulus and ultimate strength of materials were measured. On this basis, the compressive stress-strain responses and the damage evolution behavior were simulated using the two-scale, progressive damage finite element numerical method. The results from both experiment and simulation show good agreements, and indicate that the main failure mode of 2.5D woven fabric composites in weft directional compression is the axial crush and fracture of weft yarns, from which relatively higher strength is obtained. Meanwhile, additional bending moment is added to the warp yarn under warp directional compression due to bending, which causes extrusion on surrounding matrix. Therefore, matrix fracture and delamination cracking between neighboring warp yarns easily occur before the axial fracture of warp yarns, which are not conducive to utilize the advantage of fibers in bearing load, and result in relatively lower strength. ©, 2015, Beijing University of Aeronautics and Astronautics (BUAA). All right reserved.


Gao D.,Beihang University | Gao D.,AVIC Commercial Aircraft Engine CO. | Zhang Y.,Beihang University | Xu C.,National Key Laboratory of Advanced Functional Composite Materials Technology | And 2 more authors.
Ceramics International | Year: 2013

The isothermal oxidation of ZrB2 ceramics with different content of SiC was carried out in air up to 1700 °C, and the effect of chemical composition on the oxidation kinetics of ZrB2-SiC ceramics was analyzed. As indicated by the experimental results, both ceramics with 20 vol% and 30 vol% SiC particles followed near parabolic oxidation kinetics. And higher concentration of SiC led to better oxidation resistance performance due to the formation of more silica glass on the surface of the specimens and formation of zircon phase ZrSiO4. In addition, the oxidation of the ceramic composites is diffusion controlled and the activation energies for the diffusion of oxygen in the oxide scale of the ceramics oxidized at temperatures below 1500 °C were 5134 J/mol and 5960 J/mol for ZS2 and ZS3, respectively. Then the oxidation of the ceramics transformed to reaction controlled under elevated temperature due to evaporation of the protective silica glass. Furthermore, the evolution process of the surface morphology and oxide scale of the ceramic during initial oxidation stage was given detailed investigation. © 2012 Elsevier Ltd and Techna Group S.r.l.


Zhang Y.,Beihang University | Gao D.,Beihang University | Gao D.,AVIC Commercial Aircraft Engine CO. | Xu C.,National Key Laboratory of Advanced Functional Composite Materials Technology | And 2 more authors.
International Journal of Applied Ceramic Technology | Year: 2014

Dense ZrB2-SiC ceramics containing 40 vol% ZrC particles are fabricated via hot pressing method. Then the sintered ceramics are oxidized in air up to 1500°C, and the oxidation kinetics of the ceramic composites is deduced in combination with the reacted fraction curves. As indicated by the experimental results, the oxidation kinetics changes from reaction-controlled process to diffusion-controlled one with increasing of oxidation temperature. In addition, the oxidation kinetics parameters are obtained, which indicates that the oxidation resistance decays at elevated temperatures. Furthermore, the evolution of surface morphology and oxide scale during oxidation process is clarified. © 2013 The American Ceramic Society.


Gao D.,Beihang University | Zhang Y.,Beihang University | Fu J.,Beihang University | Xu C.,National Key Laboratory of Advanced Functional Composite Materials Technology | And 2 more authors.
Corrosion Science | Year: 2010

The formation and evolution of zircon during oxidation of ZrB2-20vol.% SiC ceramics under a low oxygen partial pressure of 200Pa is studied. The formation mechanism of zircon is proposed according to experimental results and thermodynamic consideration. And the main reason to the formation of zircon can be attributed to the active oxidation of SiC. Two steps can be divided for the formation and evolution of zircon: (1) nucleation from silica glass; and (2) crystal growth into prism like particles. Furthermore, the emergence of zircon significantly improves the oxidation resistance performance. © 2010 Elsevier Ltd.


Geng X.,Beihang University | Zhang Y.,Beihang University | Li Y.,Beihang University | Li S.,National Key Laboratory of Advanced Functional Composite Materials Technology | Shi X.,Beihang University
Materials Science Forum | Year: 2010

Precursor derived Si-B-C-N ceramic is a kind of amorphous materials with high hardness, low density, durability at extremely high temperature. The materials show a great potential to be used in the field of the Thermal Protective System (TPS). The physical states and chemical properties of the amorphous materials greatly depend on the starting materials. The effect of degree of polymerization (DP) of the precursor on the pyrolysis process and the characteristics of the amorphous Si-B-C-N materials are studied. The SiBCN-based preceramic polymer synthesized by dichloromethylvinylsilane, ammonia and BH3·SMe2. Dichloromethylvinylsilane reacted with ammonia and BH3·SMe2 in toluene or tetrahydrofuran (THF) as solvent in the presence of catalytic amounts of pyridine. The polymeric precursors were cured at low temperature to obtain solid-state precursors. Pyrolysis process of the solid-state precursors under various temperatures and carried out in nitrogen atmosphere. The results showed that DP of the precursor influences the pyrolysis process and the high temperature stability of the Si-B-C-N amorphous ceramics. © (2010) Trans Tech Publications.


Gao D.,Beihang University | Zhang Y.,Beihang University | Xu C.,National Key Laboratory of Advanced Functional Composite Materials Technology | Song Y.,National Key Laboratory of Advanced Functional Composite Materials Technology | Shi X.,National Key Laboratory of Advanced Functional Composite Materials Technology
Materials Chemistry and Physics | Year: 2011

Atomic oxygen is adsorbed on the surface of the hot-pressed ZrB 2-ZrC-SiC ceramic composites, and then the ceramic composites are oxidized in air up to 1500 °C with the purpose of clarifying the effect of atomic oxygen adsorption on the oxidation behaviour of the ceramic composites. The XPS spectra are employed to identify the adsorption mechanism of atomic oxygen on the surface of the ceramic composites, and the formation of O-B, O-Zr, and O-Si bonds indicates that atomic oxygen is chemically adsorbed on the surface of the ceramic. In addition, atomic oxygen is preferred to be adsorbed on the surface of borides according to the Zr 3d core level spectrum. On the other hand, the atomic oxygen adsorption is detrimental to the oxidation resistance according to experimental results, and the porosity of the ceramic should be the major reason which provides diffusion path for the atomic oxygen. Furthermore, the structure evolution of the ceramic composites during oxidation process is analyzed. © 2010 Elsevier B.V. All rights reserved.

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