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Men X.,Beihang University | Cheng Y.,Beihang University | Chen G.,Beihang University | Bao J.,Composite Technology Center | Yang J.,Beihang University
High Performance Polymers | Year: 2015

A new kind of carborane-containing aromatic diamine, 1,2-bis (4-aminophenyl)-1,2-dicarba-closo-dodecaborane (HPPA), as a curing agent for epoxy resins was synthesized and confirmed by proton, carbon and boron nuclear magnetic resonance imaging, Fourier transform infrared spectroscopy and elemental analysis. The compatibility, thermal curing behaviour and thermal properties of HPPA/epoxy resin E51 system were investigated. HPPA exhibited good compatibility with E51. Compared with 4,4′-diaminodiphenylsulphone (DDS)/E51, HPPA/E51 system had higher reaction activity and lower curing temperature. When the ratio of amine protons versus epoxy groups was 1:1 in resin systems, the epoxy resin cured by HPPA exhibited the highest glass transition temperature of 207°C. The residual weight ratios of cured HPPA/E51 at 800°C under argon and in air atmospheres were 43.7% and 50.5%, respectively, which were 28.6% and 47.2% higher than that of DDS/E51, respectively, indicating that the HPPA/E51 system had good heat resistance. © 2014 The Author(s).


Chen M.,Composite Technology Center | Qiu H.,Composite Technology Center | Jiao J.,Composite Technology Center | Li X.,Composite Technology Center | And 2 more authors.
Key Engineering Materials | Year: 2014

Equilibrium compositions of chemical vapor deposition progress for silicon carbide (CVD-SiC) coatings with MTS/H2 mixture system were calculated by means of HSC Chemistry5.0 code, and influences of the reaction temperature (T), the system pressure (P) and the composition of raw materials (molar ratio of H2 to SiCH3Cl3, β) were investigated. Thermodynamic analysis showed that the value of nc/nsic in reaction product decreased to a minimum and then increased with the increase of the reaction temperature between 700-1600°C, which meant an optimal reaction temperature existed theoretically for CVD-SiC coatings with highest purity. Furthermore, CVD-SiC coatings with high purity were obtained by experiments under the reaction pressure of 10kPa, H2/SiCH3Cl3 value of 10 and reacton temperature of 1100°C, which was in accordance with the theoretical prediction. © (2015) Trans Tech Publications, Switzerland.


Chen M.,Composite Technology Center | Qiu H.,Composite Technology Center | Xie W.,Composite Technology Center
Key Engineering Materials | Year: 2016

SiC/Si-B-C-N and SiC/SiC ceramic matrix composites were prepared through a combination of chemical vapor infiltration (CVI) and polymer impregnation pyrolysis process(PIP). The microscopic morphology and solid phase structure of the SiC/Si-B-C-N and SiC/SiC composites were investigated by SEM and XRD respectively. Moreover, the flexural strength and fracture toughness were measured using three point bending and single-edge notched beam test. Results showed that the formation of crystalline phases transformation was restrained by introduce BN into matrix phase, which might improve the stability of ceramic matrix composites. Furthermore, the flexural strength and fracture toughness of ceramic matrix composites increased to a maximum of 367 MPa and 26.81 MPa.m1/2 with the 30% PBN weight ratios which might be mainly caused by crack arresting, crack deflecting, micro cracks and fiber pullout. © 2016 Trans Tech Publications, Switzerland.


Chen M.W.,Composite Technology Center | Qiu H.P.,Composite Technology Center | Jiao J.,Composite Technology Center | Li X.Q.,Composite Technology Center | And 2 more authors.
Advanced Materials Research | Year: 2014

SiC continuous fiber reinforced SiC ceramic matrix composites (SiCf/SiC CMCs) and SiC fiber reinforced SiC micro ceramic matrix composites(SiCf/SiC micro-CMCs) were prepared through polymer impregnation pyrolysis (PIP) progress, then the structures, mechanical properties and forming mechanisms of SiCf/SiC CMCs were investigated. Results showed that volume shrinkage of SiC matrix occurred, and pyrolysates with bamboo-like layered structure were attached to the surface of SiC multifilament gradually. Furthermore, the mechanical properties of SiCf/SiC micro-CMCs were consistent with SiCf/SiC CMCs, so the PIP process parameters for the preparation of SiCf/SiC CMC might be optimized primarily through SiCf/SiC micro-CMCs, which could enhance the design and preparation efficiency of SiCf/SiC CMCs obviously. © (2014) Trans Tech Publications, Switzerland.


Li X.-Q.,Composite Technology Center | Jiao J.,Composite Technology Center | Qiu H.-P.,Composite Technology Center | Wang Y.,Composite Technology Center | And 2 more authors.
Hangkong Cailiao Xuebao/Journal of Aeronautical Materials | Year: 2014

Carbon-carbon composites of low density were prepared by chemical vapor infiltration process (CVI) using carbon felt as fiber reinforcement. ZrC/ SiC modified C/C composites were fabricated through precursor infiltration and pyrolysis process (PIP) using a hybrid precursor including polycarbosilane and organic zirconium-contained polymeric precursor as impregnant on the basis of C/C of low density. Mechanical properties and microstructural analysis were performed by Z100 universal electron test equipment and scanning electron microscope respectively. The results show that the silicon carbide phase including zirconium carbide particle dispersed symmetrical in the matrix of C/C composites, meanwhile the mechanical properties ascend earlier and descend later as the content of organic zirconium-contained polymeric precursor increased. The flexual properties and modulus maximum are 241MPa and 17.25GPa separately when the ratio of organic zirconium polymeric precursor is 25%.


Chen M.,Composite Technology Center | Qiu H.,Composite Technology Center | Jiao J.,Composite Technology Center | Wang Y.,Composite Technology Center | Xie W.,Composite Technology Center
Key Engineering Materials | Year: 2016

Oxidation thermodynamics of silicon carbide (SiC) ceramic was studied by means of HSC Chemistry code, and the weight change, morphology and phase of oxidation products were analyzed by thermogravimetric analysis(TG), scanning electron microscopy(SEM) and X-ray diffraction (XRD). The results showed that SiC ceramic could be oxidized to silicon dioxide(SiO2) with release of small molecular gases under oxidizing atmosphere at 800°C, and the formed SiO2 film with appropriate fluidity and low oxygen diffusion coefficient could prevent the spread of oxygen with the oxidation temperature increasing up to 1200°C, which favored the anti-oxidation of SiC ceramic matrix composite. © 2016 Trans Tech Publications, Switzerland.

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