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RACHMAN CHAIM ARTHUR H. HEUER R.T. CHEN 《Journal of the American Ceramic Society》1988,71(11):960-969
Several continuous SiC and SiC/N-based ceramic fibers prepared from different polymer precursors have been characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and high-resolution electron microscopy (HREM). Methods to prepare longitudinal as well as cross-sectional thin specimens from brittle ceramic fibers were developed to facilitate HREM and EELS studies. Lattice images clearly showed nanometer-sized crystallites, as well as amorphous regions. Microchemical analysis using EELS permitted study of the form and distribution of the various chemical species within the fibers. 相似文献
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Refractories and Industrial Ceramics - An effective method for preparing dense granular ceramic from SiC with a residual porosity of less than 5.0% is the use of additives of oxide system eutectic... 相似文献
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William A. Curtin Jeffrey I. Eldridge Gajawalli V. Srinivasan 《Journal of the American Ceramic Society》1993,76(9):2300-2304
Fiber push-out tests have been performed on a ceramic matrix composite consisting of Carborundum sintered SiC fibers, with a BN coating, embedded in a reaction-bonded SiC matrix. Analysis of the push-out data, utilizing the most complete theory presently available, shows that one of the fiber/coating/matrix interfaces has a low fracture energy (one-tenth that of the fiber) and a moderate sliding resistance τ∼ 8 MPa. The debonded sliding interface shows some continuous but minor abrasion, which appears to increase the sliding resistance, but overall the system exhibits very clean smooth sliding. The tensile response of a full-scale composite is then modeled, using data obtained here and known fiber strengths, to demonstrate the good composite behavior predicted for this material. 相似文献
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Conversion of Oak to Cellular Silicon Carbide Ceramic by Gas-Phase Reaction with Silicon Monoxide 总被引:7,自引:0,他引:7
Evelina Vogli Joydeb Mukerji Christiane Hoffman Ralf Kladny Heino Sieber Peter Greil 《Journal of the American Ceramic Society》2001,84(6):1236-1240
Oak has been converted to a porous biocarbon template by annealing in an inert atmosphere above 800°C. Subsequent infiltration with gaseous SiO at 1550–1600°C under flowing argon of atmospheric pressure finally resulted in the formation of a porous, cellular β-SiC ceramic. The conversion retains the biomorphic cellular morphology of oak tissue. While pores in the cell walls with a diameter less than ∼1 μm vanished, two distinct pore channel maxima representing tracheidal cells and large vessels remained in the SiC ceramic. Depending on the cellular morphology of different kinds of wood, e.g., strut thickness and pore size distribution, gas-phase conversion to single-phase β-SiC can be used to manufacture cellular ceramics with a wide range of pore channel diameters. 相似文献
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Si3 N4 ceramics reinforced with SiC platelets were fabricated by hot pressing at 1800°C. The microstructure of the Si3 N4 matrix itself was the same with or without the addition of the SiC platelets. However, the mechanical properties of the Si3 N4 were changed remarkably by the SiC addition. The fracture toughness and the crack resistance with crack propagation ( R -curve behavior) were improved while the fracture strength was decreased slightly by the platelets. Improvement in crack resistance was attributed to the extensive interaction of cracks with the platelets. The reduction in strength, on the other hand, is believed to be due to cracks associated with weak platelet-matrix interfaces. 相似文献
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由碳化硅及氮化硅制造的陶瓷材料的强度 总被引:1,自引:0,他引:1
列举了由碳化硅及氮化硅加入氧化物活化剂(Al2O3、Y2O3)制造的烧结陶瓷材料的高温强度、硬度及抗裂性的研究成果。其结果表明:由Si3N4制造的材料的强度在≥1000℃时开始下降,而由SiC制造的陶瓷则具有更高的高温强度。采用维克尔氏方法在压头受到的荷重为1kg至10kg的条件下,测定了材料的硬度和抗裂性。 相似文献
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将碳化硅(SiC)粉体和一定量聚碳硅烷(polycarbosilane,PCS)、蒸馏水、聚丙烯酰胺(polyacrylamide,PAM)、聚丙烯酸(polypropylene acid,PAA)混合球磨以制备水性SiC浆料并测定了SiC粒子的动电位及粘度;将浆料均匀涂在SiC支撑体上,在1100℃真空条件下烧成,制备了SiC陶瓷膜并测定陶瓷膜的孔径分布及纯水通量及观察其形貌.研究结果表明:涂膜所用的浆料在pH值为11左右时,SiC粒子动电位最大达到-40 mV,浆料表观粘度最小为20 mPa·s,制备的陶瓷膜孔径大小集中在1μm左右,纯水通量达40 m3/(m2·h). 相似文献
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Michael Kmetz Steven Suib Francis Galasso 《Journal of the American Ceramic Society》1990,73(10):3091-3093
Composites of SiC/Si and SiC/SiC were prepared from single yarns of SiC. The use of carbon coatings on SiC yarn prevented the degradation normally observed when chemically vapor deposited Si is applied to SiC yarn. The strength, however, was not retained when the composite was heated at elevated temperatures in air. In contrast, the strength of a SiC/C/SiC composite was not reduced after this composite was heated at elevated temperatures, even when the fiber ends were exposed. 相似文献
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Carlos G. Levi 《Journal of the American Ceramic Society》2013,96(4):1300-1308
Application of SiC‐based ceramic matrix composites (CMCs) in combustion environments demands the use of an environmental barrier coating (EBC) to prevent volatilization of the protective SiO2 scale in flowing water vapor. The EBC only provides protection while present on the surface; cracking and spallation of the coating leaves the underlying SiC vulnerable to the oxidation–volatilization processes. A robust matrix material chemically tailored to regrow a yttrium silicate scale in the event of EBC loss has been developed by incorporating yttrium bearing species including YB2, Y2O3, and Y5Si3 into the SiC. During oxidation a borosilicate glass helps seal cracks while Y2O3 and SiO2 react to form Y2Si2O7 for environmental protection. Candidate compositions were oxidized for 10 min to 100 h at 1400°C and for 24 h at 1500°C to understand the scale growth. The prospects for effectively applying this approach in CMCs are discussed. 相似文献
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Silicon Oxycarbide Ceramic Foams from a Preceramic Polymer 总被引:6,自引:0,他引:6
Open-cell ceramic foams were obtained from the pyrolysis, at 1000° to 1200°C under nitrogen, of a preceramic polymer (a silicone resin) and blown polyurethanes. The morphology of the expanded polyurethane was reproduced in the final architecture of the ceramic foam. The foams produced in this way consisted of an amorphous silicon oxycarbide ceramic (SiOC), having a bulk density ranging from 0.1 to 0.4 g/cm3 and variable cell size (300 to 600 µm). Young's modulus ranged from 20 to 170 MPa, and the compression strength from 1 to 5 MPa. The foams displayed excellent dimensional stability up to their pyrolysis temperature. 相似文献
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Kharb Sandeep Singh Antil Parvesh Singh Sarbjit Antil Sundeep Kumar Sihag Parveen Kumar Anil 《SILICON》2021,13(4):1113-1119
Silicon - The machine learning methodology is gaining immense exposure as a potential methodology for solving and modelling the machining behaviour of advanced materials. The present paper deals... 相似文献