共查询到20条相似文献,搜索用时 13 毫秒
1.
Fugitive Interfacial Carbon Coatings for Oxide/Oxide Composites 总被引:1,自引:0,他引:1
Kristin A. Keller Tai-Il Mah Triplicane A. Parthasarathy Charles M. Cooke 《Journal of the American Ceramic Society》2000,83(2):329-336
The effectiveness of fugitive interfacial carbon coatings in Nextel™ 720-based composites was investigated. Dense (>90%) matrix (calcium aluminosilicate, 0° and ±45°) composites and porous matrix (mullite/alumina, eight-harness satin fabric) composites were fabricated and tensile tested in two control conditions (uncoated or carbon-coated) and with the carbon removed (fugitive interface). Results indicated that carbon removal in dense matrix composites did not significantly change unidirectional composite strength, even after long-term exposure at 1000°C. For porous matrix composites, composite strength was independent of the fiber/matrix interface, even after exposure at 1150°C for 500 h in air. 相似文献
2.
Michael K. Cinibulk Triplicane A. Parthasarathy Kristin A. Keller Tai-Il Mah 《Journal of the American Ceramic Society》2002,85(11):2703-2710
A porous oxide fiber coating was investigated for Nextel™ 610 fibers in an alumina matrix. Polymeric-solution-derived yttrium aluminum garnet (YAG, Y3 Al5 O12 ) with a fugitive carbon phase was used to develop the porous fiber coating. Ultimate tensile strengths of tows and minicomposites following heat treatments in argon and/or air were used to evaluate the effect of the porous fiber coating. The porous YAG fiber coatings did not reduce the strength of the tows when heated in argon, and they degraded tow strength by only ∼20% after heating in air at 1200°C for 100 h. Minicomposites containing porous YAG-coated fibers were nearly twice as strong as those containing uncoated fibers. However, after heating at 1200°C for 100 h, the porous YAG coatings densified to >90%, at which point they were ineffective at protecting the fibers, resulting in identical strengths for minicomposites with and without a fiber coating. 相似文献
3.
Theodore M. Besmann Elizabeth R. Kupp Edgar Lara-Curzio Karren L. More 《Journal of the American Ceramic Society》2000,83(12):3014-3020
Silicon carbide matrix composites have been fabricated from either ceramic-grade NicalonTM or Hi-NicalonTM fibers coated with an interface material consisting of six alternating carbon and silicon carbide layers. Initial efforts involved the use of chemical vapor infiltration to produce minicomposites (single tows of fibers). In subsequent work, forced-flow thermal-gradient chemical vapor infiltration was used to produce a single composite plate with a multilayer interface from ceramic-grade Nicalon fabric and two plates from Hi-Nicalon fabric, one with a single carbon layer and one with a multilayer interface. Tensile testing of the minicomposites and of specimens cut from the plates revealed typical composite behavior and strengths for the as-processed samples. Exposure of tensile specimens to 950°C air for 100 h resulted in large losses in strength and strain tolerance regardless of the interface coating. The results demonstrate that forced-flow thermal-gradient chemical vapor infiltration can be used to prepare multilayer interface material. The results also verified that relatively thick (>100 nm) single or multiple carbon layers are susceptible to oxidation that causes the loss of composite properties. 相似文献
4.
Laifei Cheng Yongdong Xu Litong Zhang Xiaowei Yin 《Journal of the American Ceramic Society》2002,85(4):989-991
A carbon-fiber-reinforced silicon carbide composite (3D-C/SiC) was prepared by chemical vapor infiltration. A SiC and SiC/Si-Zr coating were deposited on the composite to investigate the effect of different coatings on the oxidation behavior of 3D-C/SiC composites. The 3D-C/SiC(SiC/Si-Zr) composite decreased in weight below 1000°C and increased in weight above 1000°C. With an increasing oxidation time, the weight loss increased greatly and the weight gain increased little. The 3D-C/SiC(SiC) composite always decreased in weight over the full temperature range. With an increasing oxidation time, the weight loss increased rapidly below 1000°C and reached its minimum value at 1400°C. The 3D-C/SiC(SiC/Si-Zr) composite had a higher oxidation resistance above 1000°C, and the 3D-C/SiC(SiC) composite had a higher oxidation resistance below 1000°C. The wider the coating cracks, the larger the maximum weight loss and the lower the temperature corresponding to the maximum weight loss. With an increasing oxidation time, the activation energy of the 3D-C/SiC(SiC/Si-Zr) composite increased from 96 to 138 kJ/mol, and the 3D-C/SiC(SiC) composite increased from 130 to 180 kJ/mol. 相似文献
5.
Pavel Mogilevsky Randall S. Hay Emmanuel E. Boakye Kristen A. Keller 《Journal of the American Ceramic Society》2003,86(10):1767-1772
Microstructure and texture development of fiber coatings of rhabdophane-sol-derived monazite was studied. As-deposited textures and orientation relationships during phase transformations were determined by TEM. Monazite coatings had a crystallographic texture relict from that of as-deposited rhabdophane, with layers of rod-shaped particles that changed orientation by 90° across layers. Heat treatment at 1200°C of minicomposites with these coated fibers caused considerable monazite grain coarsening, and disappearance of the texture. 相似文献
6.
Dong-Hau Kuo Waltraud M. Kriven Thomas J. Mackin 《Journal of the American Ceramic Society》1997,80(12):2987-2996
Fiber pushout tests were used to quantify the effects of fiber coating thickness on the mechanical properties of two model composite systems: a monazite-coated (LaPO4 -coated) alumina (Al2 O3 ) fiber in an Al2 O3 matrix and a LaPO4 -coated yttrium aluminum garnet (YAG) fiber in an Al2 O3 matrix. Interface properties were quantified using the Liang and Hutchinson (LH) pushout model and mechanistically rationalized by considering the change in residual thermal stresses with changes in the coating thickness. Measures of the pure Mode II interfacial fracture energy, the coefficient of friction, and a radial clamping pressure are extracted by fitting the LH equations to the experimental results. Using the approach that has been developed herein, a methodology is available for measuring the interfacial properties, predicting the effect of coating thickness, and selecting the coating thickness to 相似文献
7.
Influence of Interfacial Roughness on Fiber Sliding in Oxide Composites with La-Monazite Interphases
Janet B. Davis Randall S. Hay David B. Marshall Peter E. D. Morgan Ali Sayir 《Journal of the American Ceramic Society》2003,86(2):305-316
Room-temperature debonding and sliding of fibers coated with La-monazite is assessed using a composite with a polycrystalline alumina matrix and fibers of several different single crystal (mullite and sapphire) and directionally solidified eutectic (Al2 O3 /Y3 Al5 O12 and Al2 O3 /Y-ZrO2 ) compositions. These fibers provide a range of residual stresses and interfacial roughnesses. Sliding occurred over a debond crack at the fiber-coating interface when the sliding displacement and surface roughness were relatively small. At large sliding displacements with relatively rough interfaces, the monazite coatings were deformed extensively by fracture, dislocations, and occasional twinning, whereas the fibers were undamaged. Dense, fine-grained areas (10 nm grain size) resembling recrystallized microstructures were also observed in the most heavily deformed regions of the coatings. Frictional heating during sliding is assessed. Potential mechanisms for forming such microstructures at low temperature are discussed, and a parallel is drawn with the known resistance of monazite to radiation damage. The ability of La-monazite to undergo both debonding and plastic deformation relatively easily at low temperatures may enable its use as a composite interface. 相似文献
8.
论述了钢坯在高温下的氧化机理及其防护涂料的发展现状。研制了一种水性耐高温抗氧化无机涂料,其可常温干燥,能够防止钢坯脱碳和抗氧化。对产品的应用结果进行了分析。 相似文献
9.
Yttrium silicate (Y2 SiO5 ) coatings complement SiC coatings for protecting ceramic multilayer composite materials based on carbon-fiber-reinforced SiC composites (C-SiC). Thick (100 μm), dense Y2 SiO5 coatings were prepared by dip coating, using concentrated aqueous slips. The resulting phases were studied by taking into account the simultaneous presence of oxide and non-oxide materials, which affected the chemical stability of the coatings. Thick, mechanically stable coatings were obtained by sintering in carbon crucibles and a SiC bed in an argon-flow furnace. Pure Y2 SiO5 coatings completely separated from the SiC substrates. A high percentage of Y2 Si2 O7 was necessary to fit the thermal expansion coefficients and ensure the stability of the coatings. Oxidation resistance of the coated substrates was investigated by isothermal and stepwise oxidation tests. 相似文献
10.
Monazite was continuously coated onto Nextel 720 fibers, using an aqueous precursor and in-line heat treatment at 900°–1300°C. Some experiments were repeated with alumina-doped precursors. Coated fibers were heat-treated for 100 h at 1200°C. Coatings were characterized by optical microscopy, scanning electron microscopy, and analytical transmission electron microscopy. Coated-fiber tensile strengths were measured by single-filament tensile tests. The precursors were characterized by X-ray diffractometry, differential thermal analysis/thermogravimetric analysis, and mass spectrometry. Coated-fiber tensile strength was lower for fibers coated at higher deposition temperatures. Heat treatment for 100 h at 1200°C decreased tensile strength further. The coatings were slightly phosphate-rich and enhanced alumina grain growth at the fiber surface, but phosphorus was not detected along the alumina grain boundaries. Fibers with alumina-doped coatings had higher tensile strengths than those with undoped coatings after heat treatment for 100 h at 1200°C. Alumina added as α-alumina particles gave higher strengths than alumina added as colloidal boehmite. Alumina doping slowed monazite grain growth and formed rough fiber–coating interfaces after 100 h of heat treatment at 1200°C. Possible relationships among precursor characteristics, coating and fiber microstructure development, and strength-degradation mechanisms are discussed in this paper. 相似文献
11.
12.
Developing Interfacial Carbon-Boron-Silicon Coatings for Silicon Nitride-Fiber-Reinforced Composites for Improved Oxidation Resistance 总被引:2,自引:0,他引:2
Kiyoshi Sato Hiroki Morozumi Osamu Funayama Hiroshi Kaya Takeshi Isoda 《Journal of the American Ceramic Society》2002,85(7):1815-1822
C-B-Si coatings were formed on a Si3 N4 fiber using chemical vapor deposition and embedded in a Si-N-C matrix using polymer impregnation and pyrolysis. The boron-containing layer was anticipated to form borosilicate glass and seal oxygen-diffusion passes. Two types of C-B-Si coatings were tested on the fiber–matrix interface, and they improved the oxidation resistance of the composite. The first coating was multilayered: a crystalline sublayer composed of B-Si-C was sandwiched between two graphitelike carbon sublayers. The second coating was a graphitelike carbon layer containing a small amount of boron and silicon. The carbon (sub)layer of both coatings weakened the fiber–matrix bonding, giving the composites a high flexural strength (1.1 GPa). The composites retained 60%–70% of their initial strength, even after oxidation at 1523 K for 100 h. The mechanism for improved oxidation resistance was discussed through the microstructure of the interface, morphology of the fracture surface, and oxygen distribution on a cross section of the oxidized composite. 相似文献
13.
14.
以一种市售重防腐涂料配方为基础配方,通过添加有机硅树脂、SiC微粉、硅烷偶联剂等组分,研制出一种改进型耐高温防腐涂料,并对添加的组分在耐高温防腐涂料中的作用机理以及对涂层性能的影响进行了讨论.实验结果表明,有机硅树脂、SiC微粉的加入,使原涂层的最高耐热温度从230℃上升到390℃,大大提高了涂层的耐热性;SiC微粉和硅烷偶联剂的加入量分别为7 g和0.6 g时,涂层的综合性能最佳. 相似文献
15.
16.
环氧改性有机硅耐高温防腐隔热涂料的研制 总被引:1,自引:0,他引:1
以环氧改性有机硅树脂为成膜物,以复合铁钛粉为防锈颜料,以六钛酸钾晶须、海泡石、膨胀蛭石、空心玻璃微珠等轻质材料为填料,在多种助剂和低相对分子质量聚酰胺的配用下,制得一种综合性、实用性、经济性较好的双组分耐高温防腐隔热涂料。 相似文献
17.
选取硼酸高温脱水后的混合物作为填料,与高岭土、滑石粉、铝粉等填料制备了以有机硅树脂为基料,可以耐受800℃的耐高温防护涂层并测试了涂层的各项性能。为研究硼酸混合物在涂层高温灼烧过程中的作用机理,对涂层在经200℃固化、500℃高温灼烧和700℃高温灼烧后的表层形貌、元素和涂层物质变化情况进行分析。阐明了涂层中有机硅树脂上的有机基团会在500℃时大量分解。硼酸混合物在高温下,会以熔融态填充有机硅树脂分解挥发产生的空隙,并粘接其他颜填料,但是涂层表面会有硼酸混合物脱水造成的少量凹陷存在。 相似文献
18.
连续SiC纤维增韧SiC陶瓷基复合材料(SiCf/SiC CMCs)具有低密度、优异的高温力学性能和抗氧化性能,在航空发动机热端部件上具有广阔的应用前景,具备提高发动机推重比和使用温度、减轻无效重量、简化系统结构等显著优势.延长SiCf/SiC复合材料在航空发动机高温氧化环境下的服役寿命是当前需要解决的难题.本文从纤维、界面相、基体、表面涂层四个方面综述了SiCf/SiC复合材料高温抗氧化研究进展.采用多元多层自愈合界面相、对基体进行改性以及采用表面自愈合整体涂层都可以有效提高SiCf/SiC复合材料在高温氧化环境中的使用稳定性和寿命. 相似文献
19.
20.
对一种使用温度在700℃以上的保温隔热涂料,在实际使用中的保温隔热性能进行检测,该涂料在850℃下2 min后隔热温度在200℃以内,在700℃下5 min后隔热温度为285℃,适用于700℃以上高温环境下需要短时间隔热保护的产品。 相似文献