共查询到20条相似文献,搜索用时 15 毫秒
1.
Raghavarapu Venkata Krishnarao Mahadev Malhar Godkhindi 《Journal of the American Ceramic Society》1991,74(9):2315-2317
Diffusion bonding of dense Si3 N4 containing 10% Ce2 O3 , 7% A12 O3 , and 2% Y2 O3 was attempted through hot pressing at temperatures of 1000° to 1400°C. Physically vapor-deposited (PVD) carbon and paraffin-wax candle soot were tried as interlayers. The interfaces were analyzed through optical and scanning electron microscopy, and through X-ray photoelectron spectroscopy. The bonding temperature could be reduced from 1400° (without interlayers) to 1100°C with PVD carbon or candle soot. From C Is and Si 2p spectra, the formation of SiC at the interface through the reaction of C with the silicon oxynitride layer has been identified. 相似文献
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Maria Antonia Sainz Pilar Miranzo Maria Isabel Osendi 《Journal of the American Ceramic Society》2002,85(4):941-946
Dense hot-pressed β-Si3 N4 blocks were joined using both SiO2 and SiO2 -Y2 O3 powder slurries as bonding interlayers. The assembled specimens (Si3 N4 /interlayer/Si3 N4 ) were heated in a flowing N2 atmosphere in the temperature range of 1500°–1650°C. The joining interlayer was clearly distinguished from the Si3 N4 bulk. The microstructure and the reaction products found in the bonding interlayer were very different in both compositions. Reactions occurring between the Si3 N4 and the ceramic joining compositions have been explained based on existing diagrams of the YN–Si3 N4 -Y2 O3 -SiO2 system. 相似文献
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Mani Gopal Mark Sixta Lutgard De Jonghe Gareth Thomas 《Journal of the American Ceramic Society》2001,84(4):708-712
High-strength joining of Si3 N4 ceramics has been achieved by developing a process that effectively eliminates the seam, and may allow for fabrication of large or complex silicon nitride bodies. This approach to joining is based on the concept that when sintering aids are effective in bonding individual grains, they could be equally effective in joining bulk pieces of Si3 N4 . Optimization of the process led to Si3 N4 /Si3 N4 joints with room-temperature bend strengths as high as 950 MPa, corresponding to more than 90% of the bulk strength of the Si3 N4 . At elevated temperatures of 1000° and 1200°C joint strengths of 666 and 330 MPa, respectively, were obtained, which are the highest values reported to date for these temperatures. These bend strengths are also more that 90% of the strength of bulk Si3 N4 measured at these temperatures. 相似文献
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Liquid-Phase Bonding of Silicon Nitride Ceramics 总被引:1,自引:0,他引:1
Mg-Si-O-N glasses were used to bond dense Si3 N4 ceramic pieces by a liquid-phase diffusion bonding mechanism. In this case, it was difficult to achieve defect-free bonding because, at low nitrogen content in the glass, a large mismatch in thermal expansion coefficient produced cracks perpendicular to the bonding glass layer. With an increase in nitrogen content, the glass layer became frothy and contained "bubbles." However, when a small amount of elemental silicon was added to the glass, volatile reaction was suppressed and intimate bonding was achieved without thermal cracks. 相似文献
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Ronald E. Loehman Antoni P. Tomsia Joseph A. Pask Sylvia M. Johnson 《Journal of the American Ceramic Society》1990,73(3):552-558
We investigated the wetting behavior and reactions of different metals on Si3 N4 using sessile drop measurements, analysis of reaction layers, and measurements of strengths of joined bars. Active metals, such as Al and Ti, and alloys that contain them react with Si3 N4 and cause wetting and spreading at the interface. Al-Si3 N4 reaction at 900°C produced a thin layer of Al2 O3 at the interface. Reaction between Si3 N4 and Ag-Cu-To braze alloys at 900°C resulted in a complex microstructure in the reaction zone that contained TiN and titanium silicides. Breaking strengths of Si3 N4 bars joined with the Ag-Cu-Ti braze alloys were higher than those for Si3 N4 joined with Al, primarily because of the better wetting by the Ag-Cu-Ti alloys. Nonreactive metals and alloys such as Sn, In, Ag-Cu, and Ag-Cu-Sn neither wet, spread, nor adhere to Si3 N4 substrates. 相似文献
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刘大成 《陶瓷研究与职业教育》2000,(4)
分析了二氧化锆的性质及氧空位对二氧化锆相变的影响 ,讨论了二氧化锆韧化氮化硅陶瓷的影响因素 ,提出了二氧化锆韧化氮化硅陶瓷时避免氮化锆生成、促进复相氮化硅陶瓷烧结的途径。 相似文献
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Kenji Hatanaka Masashi Katsuyama Hideki Takagi 《Journal of the American Ceramic Society》2003,86(1):135-140
The fatigue tests under push-pull completely reversed loading and pulsating loading were performed for silicon nitride ceramics at elevated temperatures. Then the effects of stress wave form, stress rate, and cyclic understressing on fatigue strength, and cyclic straining behavior, were examined. The cycle-number-based fatigue life is found to be shorter under trapezoidal stress wave loading than under triangular stress wave loading, and to become shorter with increasing hold time under the trapezoidal stress wave loading. Meanwhile, the equivalent time-based life curve, which is estimated from the concept of slow crack growth, almost agrees with the static fatigue life curve in the short and intermediate life regions, showing the small cyclic stress effect and the dominant stress-imposing period effect on cyclic fatigue life. The fatigue strength increased in stepwise stress amplitude increasing test, where stress amplitude is increased stepwise every given number of stress cycles, at 1100° and 1200°C. Occurrence of cyclic strengthening was proved through a gradual decrease in strain amplitude during a pulsating loading test at 1200°C in this material, corresponding to the above cyclic understressing effect on fatigue strength. 相似文献
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John S. Haggerty A. Lightfoot John E. Ritter Paul A. Gennari S. V. Nair 《Journal of the American Ceramic Society》1989,72(9):1675-1679
Reaction-bonded Si3 N4 (RBSN) made from high-purity Si powder is unusually resistant to degradation caused by exposures to air for up to 50 h at temperatures up to 1400°C. The weight gain during oxidation of this SiH4 -originating RBSN is approximately 10 times less than conventional RBSN. Contrary to normally observed strength degradations, room-temperature strengths of this high-purity, oxidized RBSN (avg = 435 MPa, max. = 668 MPa) remained at their unusually high, as-processed levels after 1000° and 1400°C oxidizing exposures. Fracture toughness values were unaffected by oxidation ( K IC = 2.3 to 2.4 MPa · m1/2 ). This superior oxidation resistance results from the high purity and the small diameter pore channels (0.01 to 0.06 μm) achieved in this SiH4 -originating RBSN. 相似文献
12.
Yanan N. Liang Maria Isabel Osendi Pilar Miranzo 《Journal of the American Ceramic Society》2003,86(7):1226-1229
Mechanical pressure exerts a noticeable effect on the reaction that takes place at the interfacial region of Si3 N4 /Ni-Cr-B/Si3 N4 joints. In fact, the mechanical pressure affects the thickness of the reaction layer: for lower pressures, a large interfacial reaction layer and a profusion of cracks are observed, whereas, for higher pressures, the extent of the reaction layer is limited, and no cracks are detected. The results show that joint strength increases monotonically with applied pressure. 相似文献
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Layered Silicon Nitride-Based Composites with Discontinuous Boron Nitride Interlayers 总被引:1,自引:0,他引:1
Zoltán Lené Kiyoshi Hirao Manuel E. Brito Motohiro Toriyama Shuzo Kanzaki 《Journal of the American Ceramic Society》2000,83(10):2503-2508
The influence of a strong/weak interface ratio on the mechanical properties of Si3 N4 /BN-based layered composites was studied. The ratio was controlled by the number of BN spots between the adjacent Si3 N4 layers. By increasing the BN interface area from 0% to 72%, fracture toughness increased from 7.7 to 10.9 MPa·m1/2 , and bending strength decreased from 1275 to 982 MPa. Fracture toughness was improved from 8.6 to 10.1 MPa·m1/2 by additional heat treatment of samples containing 2 vol%β-Si3 N4 seed particles. The bending strength of samples with 35% weak BN interfaces, measured perpendicular and parallel to layer alignment, was 1260 and 1240 MPa, respectively. This confirmed the two-directional isotropy of layered samples. 相似文献
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以α-Si3N4粉末为原料,Y2O3和MgAl2O4体系为烧结助剂,采用无压烧结方式,研究了烧结温度、保温时间、烧结助剂含量以及各组分配比对氮化硅致密化及力学性能的影响。结果表明:以Y2O3和MgAl2O4为烧结助剂体系,氮化硅陶瓷在烧结温度为1 600 ℃,保温时间为4 h,烧结助剂含量为12.5%(质量分数),Y2O3和MgAl2O4质量比为1∶1时,综合性能最好;氮化硅陶瓷显气孔率为0.21%,相对密度为98.10%,抗弯强度为598 MPa,维氏硬度为15.55 GPa。 相似文献
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Computer Simulation of the Microstructure Developed in Reaction-Sintered Silicon Nitride Ceramics 总被引:1,自引:0,他引:1
Wenfu Ku Otto J. Gregory Hamlin M. Jennings 《Journal of the American Ceramic Society》1990,73(2):286-296
A simulation model of the microstructure developed during the reaction sintering of ultrafine silicon powders is presented. The model employs interactive subroutines that describe particle compaction, sintering, and nitridation. The particle compaction model is based on a random particle packing model, whereas the sintering and reaction sintering models are based on the modified grain model and the sharp interface model (SIM). Microstructural changes due to the competition between chemical reaction and sintering are taken into account in the model. The results predicated by this model show good agreement with experimental data from previous studies. 相似文献
17.
Brian W. Sheldon 《Journal of the American Ceramic Society》1996,79(11):2993-2996
The oxidation kinetics of Si3 N4 were modeled by describing the simultaneous diffusion and reaction of interstitial oxygen that is believed to occur inside of the silicon oxynitride interlayer. The oxynitride was assumed to have a variable composition, and oxidation was described as a reaction where interstitial oxygen is incorporated into the network structure of the oxynitride and nitrogen is removed. It was assumed that both the diffusion coefficient and the solubility of interstitial oxygen decrease as the nitrogen content of the network structure increases. The results accurately describe both the formation of an oxynitride layer during oxidation, and the relatively slow oxidation kinetics of Si3 N4 (compared to Si and SiC). 相似文献
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Jeffrey D. Bright Dinesh K. Shetty Curtis W. Griffin Santosh Y. Limaye 《Journal of the American Ceramic Society》1989,72(10):1891-1898
Interfacial shear strength and interfacial sliding friction stress were assessed in unidirectional SiC-filament-reinforced reaction-bonded silicon nitride (RBSN) and borosilicate glass composites and 0/90 cross-ply reinforced borosilicate glass composite using a fiber pushout test technique. The interface debonding load and the maximum sliding friction load were measured for varying lengths of the embedded fibers by continuously monitoring the load during debonding and pushout of single fibers in finite-thickness specimens. The dependences of the debonding load and the maximum sliding friction load on the initial embedded lengths of the fibers were in agreement with nonlinear shear-lag models. An iterative regression procedure was used to evaluate the interfacial properties, shear debond strength (T d ), and sliding friction stress (T f ), from the embedded fiber length dependences of the debonding load and the maximum frictional sliding load, respectively. The shear-lag model and the analysis of sliding friction permit explicity evaluation of a coefficient of sliding friction (μ) and a residual compressive stress on the interface (σ0 ). The cross-ply composite showed a significantly higher coefficient of interfacial friction as compared to the unidirectional composites. 相似文献
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