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1.
Yangyang Hu Zhaoqiang Chen Jingjie Zhang Guangchun Xiao Mingdong Yi Wenliang Zhang Chonghai Xu 《Journal of the American Ceramic Society》2019,102(11):6991-7002
A new type of reduced graphene oxide-encapsulated silicon nitride (Si3N4@rGO) particle was synthesized via an electrostatic interaction between amino-functionalized Si3N4 particles and graphene oxide (GO). Subsequently, the Si3N4@rGO particles were incorporated into a Si3N4 matrix as a reinforcing phase to prepare nanocomposites, and their influence on the microstructure and mechanical properties of the Si3N4 ceramics was investigated in detail. The microstructure analysis showed that the rGO sheets were uniformly distributed throughout the matrix and firmly bonded to the Si3N4 grains to form a three-dimensional carbon network structure. This unique structure effectively increased the contact area and load transfer efficiency between the rGO sheets and the matrix, which in turn had a significant impact on the mechanical properties of the nanocomposites. The results showed that the nanocomposites with 2.25 wt.% rGO sheets exhibited mechanical properties that were superior to monolithic Si3N4; the flexural strength increased by 83.5% and reached a maximum value of 1116.4 MPa, and the fracture toughness increased by 67.7% to 10.35 MPa·m1/2. 相似文献
2.
Stress distribution around Fe5Si3 and its effect on interface status and mechanical properties of Si3N4 ceramics
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Lujie Wang Qian Qi Haibo Wu Hui Zhang Jie Yin Yong Yang Jian Huang Xiao Yang Xuejian Liu Zhengren Huang 《Journal of the American Ceramic Society》2018,101(2):856-864
Si3N4 ceramics with different amount of Fe5Si3 were prepared by adding FeSi2. Residual thermal stress distribution and elastic energy around Fe5Si3 particles in various depths were calculated. The interface status between second phase particles and matrix was analyzed in terms of stress and energy. High tangential compressive stresses and low radial tensile stresses were generated along the surface of the ceramics. Elastic strain energy caused by unit interface was high around big particles in deep area of the ceramics. Microcracks are observed around the big Fe5Si3 particles. Furthermore, accord to our calculation, microcracks are easily generated around particles in superficial layer of matrix when second phase particles have lower thermal expansion coefficient than the matrix, while microcracks tend to be generated in deep layer of matrix preferentially when the thermal expansion coefficient of second phase particles is higher than matrix. Residual stresses and microcracks around Fe5Si3 particles greatly influenced mechanical properties. Fracture toughness of Si3N4 ceramics with similar Si3N4 particle size distribution increased with the amount of Fe5Si3, and fine Fe5Si3 particles could enhance the strength of Si3N4 ceramics. Si3N4 ceramics exceeding 1.2 GPa strength were prepared. 相似文献
3.
Minzhong Huang Yao Huang Jun Ou Yangyang Wu Junye Wang Shanghua Wu 《International Journal of Applied Ceramic Technology》2022,19(6):3403-3409
Enhancement of the thermal conductivity of silicon nitride is usually achieved by sacrificing its mechanical properties (bending strength). In this study, β-Si3N4 ceramics were prepared using self-synthesized Y3Si2C2 and MgO as sintering additives. It was found that the thermal conductivity of the Si3N4 ceramics was remarkably improved without sacrificing their mechanical properties. The microstructure and properties of the Si3N4 ceramics were analyzed and compared with those of the Y2O3-MgO additives. The addition of Y3Si2C2 eliminated the inherent SiO2 and introduced nitrogen to increase the N/O ratio of the grain-boundary phase, inducing Si3N4 grain growth, increasing Si3N4 grain contiguity, and reducing lattice oxygen content in Si3N4. Therefore, by replacing Y2O3 with Y3Si2C2, the thermal conductivity of the Si3N4 ceramics was significantly increased by 31.5% from 85 to 111.8Wm−1K−1, but the bending strength only slightly decreased from 704 ± 63MPa to 669 ± 33MPa. 相似文献
4.
Composite ceramic materials based on Si3 N4 and ZrO2 stabilized by 3 mol% Y2 O3 have been formed using aluminum isopropoxide as a precursor for the Al2 O3 sintering aid. Densification was carred out by hot-pressing at temperatures in the range 1650° to 1800°C, and the resulting micro-structures were related to mechanical properties as well as to oxidation behavior at 1200°C. Densification at the higher temperatures resulted in a fibrous morphology of the Si3 N4 matrix with consequent high room-temperature toughness and strength. Decomposition of the ZrO2 grains below the oxidized surface during oxidation introduced radial stresses in the subscalar region, and from the oxidation experiments it is suggested that the ZrO2 incorporated some N during densification. 相似文献
5.
Ning Liu Tengfei Hu Yusen Duan Jingxian Zhang Xiaoguang Li Shaoming Dong 《International Journal of Applied Ceramic Technology》2022,19(3):1255-1264
In this paper, silicon nitride (Si3N4) ceramics with black color and high toughness were fabricated by gas pressure sintering and characterized by X-ray diffraction, Raman, scanning electron microscopy, EDS, and transmission electron microscopy. The in situ formed cobalt silicide was confirmed to contribute to the black color through the introduction of CoO. Due to the addition of CoO, the growth of β-Si3N4 grains is promoted, forming elongated grains, and eventually forms the self-reinforcing microstructure. However, with adding excessive CoO, interfacial debonding is found between cobalt silicide and Si3N4 matrix and a decrease in strength was resulted. The optimum composition is 1 mol% CoO in Si3N4, with the fracture toughness of 9.9 ± 0.3 MPa m1/2, flexural strength of 826.1 ± 46.0 MPa, and a much darker black color. The mechanism of color formation is discussed where the black color derives mainly from the metallic silicon and additionally the porosity. 相似文献
6.
Shi Fu Zengchao Yang Honghua Li Liang Wang Yong Li Jiangtao Li 《International Journal of Applied Ceramic Technology》2023,20(3):1855-1864
Si3N4 ceramics were prepared by gas pressure sintering at 1900°C for 12 h under a nitrogen pressure of 1 MPa using Gd2O3 and MgSiN2 as sintering additives. The effects of the Gd2O3/MgSiN2 ratio on the densification, microstructure, mechanical properties, and thermal conductivity of Si3N4 ceramics were systematically investigated. It was found that a low Gd2O3/MgSiN2 ratio facilitated the thermal diffusivity of Si3N4 ceramics while a high Gd2O3/MgSiN2 ratio benefited the densification and mechanical properties. When the Gd2O3/MgSiN2 ratio was 1:1, Si3N4 ceramics obtained an obvious exaggerated bimodal microstructure and the optimal properties. The thermal conductivity, flexural strength, and fracture toughness were 124 W·m−1·k−1, 648 MPa, and 9.12 MPa·m1/2, respectively. Comparing with the results in the literature, it was shown that Gd2O3-MgSiN2 was an effective additives system for obtaining Si3N4 ceramics with high thermal conductivity and superior mechanical properties. 相似文献
7.
Jiongjie Liu Jun Yang Shengyu Zhu Jun Cheng Yuan Yu Zhuhui Qiao Weimin Liu 《Journal of the American Ceramic Society》2019,102(7):4333-4343
Si3N4 as a structural ceramic is desirable for applications in spacecraft, transportation, and energy, but its poor high-temperature properties still do not satisfy the actual requirements. Here, a TiC0.3N0.7 reinforced Si3N4 ceramic is successfully designed and fabricated via the high-temperature nitridation of TiCx. It is found that TiC0.3N0.7 grains with the size of 1-2 μm are uniformly dispersed in the Si3N4 matrix and show a firm bond with substrate. Compared with pure Si3N4, the doping of harder TiCN phase can effectively improve ceramic's hardness and fracture toughness at a certain temperature. Importantly, the ceramic material displays extraordinary wear resistance across a wide temperature range (eg, the wear rate of TiC0.3N0.7 containing Si3N4 over 63 times and 178 times better than pure Si3N4 at 600 and 900°C, respectively). More broadly, a correlation between wear mechanism and temperature is established, and the result shows that the mechanical strength and tribochemical oxidation as two key factors determine the wear behavior of the material. These results developed here can provide a springboard for preparation and optimization of multiphase ceramics that serve under high-temperature conditions. 相似文献
8.
Texture,microstructures, and mechanical properties of AlN‐based ceramics with Si3N4–Y2O3 additives
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Cong Liu Wei‐Ming Guo Shi‐Kuan Sun Ji Zou Shang‐Hua Wu Hua‐Tay Lin 《Journal of the American Ceramic Society》2017,100(8):3380-3384
Textured AlN‐based ceramics with improved mechanical properties were prepared by hot pressing using Si3N4 and Y2O3 as additives. The introduction of Si3N4–Y2O3 into AlN matrix led to the formation of secondary Y3AlSi2O7N2 and fiber‐like 2Hδ AlN‐polytypoid phases, the partial texture of all crystalline phases, and the fracture mode change from intergranular to transgranular. Consequently, Vickers hardness, fracture toughness and flexural strength of AlN‐based ceramics by the replacement of Y2O3 by Si3N4–Y2O3 increased significantly from 10.4±0.3 GPa, 2.4±0.3 MPa m½ and 333.3±10.3 MPa to 14.2±0.4 GPa, 3.4±0.1 MPa m½ and 389.5±45.5 MPa, respectively. 相似文献
9.
Yinsheng Li Ha‐Neul Kim Haibo Wu Mi‐Ju Kim Jae‐Woong Ko Young‐Jo Park Zhengren Huang Hai‐Doo Kim 《Journal of the American Ceramic Society》2018,101(9):4128-4136
Si3N4 ceramic was densified at 1900°C for 12 hours under 1 MPa nitrogen pressure, using MgO and self‐synthesized Y2Si4N6C as sintering aids. The microstructures and thermal conductivity of as‐sintered bulk were systematically investigated, in comparison to the counterpart doped with Y2O3‐MgO additives. Y2Si4N6C addition induced a higher nitrogen/oxygen atomic ratio in the secondary phase by introducing nitrogen and promoting the elimination of SiO2, resulting in enlarged grains, reduced lattice oxygen content, increased Si3N4‐Si3N4 contiguity and more crystallized intergranular phase in the densified Si3N4 specimen. Consequently, the substitution of Y2O3 by Y2Si4N6C led to a great increase in ~30.4% in thermal conductivity from 92 to 120 W m?1 K?1 for Si3N4 ceramic. 相似文献
10.
Young-Hag Koh Hae-Won Kim Hyoun-Ee Kim John W. Halloran 《Journal of the American Ceramic Society》2002,85(12):3123-3125
The oxidation behavior and its effect on the mechanical properties of fibrous monolith Si3 N4 /BN after exposure to air at temperatures ranging from 1000° to 1400°C for up to 20 h were investigated. After exposure at 1000°C, only the BN cell boundary was oxidized, forming a B2 O3 liquid phase. With increasing exposure temperature, the Si3 N4 cells began to oxidize, forming crystalline Y2 Si2 O7 , SiO2 , and silicate glass. However, in this case, a weight loss was observed due to extensive vaporization of the B2 O3 liquid. After exposure at 1400°C, large Y2 Si2 O7 crystals with a glassy phase formed near the BN cell boundaries. The oxidation behavior significantly affected the mechanical properties of the fibrous monolith. The flexural strength and work-of-fracture decreased with increasing exposure temperature, while the noncatastrophic failure was maintained. 相似文献
11.
12.
Si3N4对硫系玻璃的热学和力学性质的影响 总被引:1,自引:0,他引:1
对在两个硫系玻璃系统中引入Si3N4所产生的效应进行了研究,发现其影响程度与基玻璃的组成有关。用描述共价键固体交连程度的系统平均配位数概念讨论了这种关系。发现与处于富硫族元素组成区的硫系玻璃相比,在处于富阳性元素组成区的硫系玻璃中引入Si3N4对玻璃热、力学性能的改善程度较低。这是因为没有足够的硫族元素起连接作用,多余的Si并不能对网络交连程度的提高做贡献。进一步的研究结果证实了在不同组成区引入Si3N4对玻璃转变温度θg的不同影响。在富阳性元素组成区θg甚至随系统平均配位数的增加而略有提高的原因则在于“错键效应”对玻璃网络所可能起到的局部连接作用。 相似文献
13.
14.
Shuqi Guo 《Journal of the American Ceramic Society》2019,102(6):3286-3295
In this study, a homogenously dispersed finer SiC particles-containing ZrB2 composite was prepared using nanosized polycarbosilane (PCS) particles-containing ZrB2 mixture powder, followed by hot pressing. The microstructure of the resulting composite was characterized by field-emission scanning electron microscopy and transmission electron microscopy. The composite microstructure comprised finer equiaxed ZrB2 and SiC grains. The mechanical behavior of the composite was evaluated using four-point bending test at different temperatures between room temperature (RT) and 1600°C. The results show that the composite exhibited only linear deformation behavior prior fracture at or below 1500°C. However, a trace quantity of nonlinear deformation was observed at 1600°C. In addition, the flexural strength of the composite decreased as the temperature increased from RT to 1200°C, then the strength increased as the temperature raised to 1400°C. Subsequently, the flexural strength remained almost the constant between 1400°C and 1600°C, with a strength of ~760 MPa. 相似文献
15.
Effect of ZrB2 content on phase assemblage and mechanical properties of Si3N4–ZrB2 ceramics prepared at low temperature
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Wei‐Ming Guo Li‐Xiang Wu Jun‐Jie Yu Ling‐Yong Zeng Shi‐Kuan Sun Jing‐Xi Li Shang‐Hua Wu Hua‐Tay Lin Cheng‐Yong Wang 《Journal of the American Ceramic Society》2018,101(11):4870-4875
Based on the previous work on Si3N4–ZrB2 [Wu et al. J Eur Ceram Soc;2017,37:4217], the influence of ZrB2 addition on the phase and microstructure evolution of Si3N4–ZrB2 composites was emphatically investigated, and the mechanical properties were compared with pure Si3N4 ceramics. It was revealed that the ratio of β‐ to (α+β)‐Si3N4 significantly increased from 14.3% in pure Si3N4 ceramics to 39.8% in Si3N4 with 15 vol% ZrB2 addition, indicating that the introduction of ZrB2 promoted α‐ to β‐Si3N4 phase transformation. As a consequence, the microstructure of the composite showed the bimodal distribution, containing both elongated and equiaxed Si3N4 grains. For the pure Si3N4, Vickers hardness, fracture toughness and flexural strength was 22.8 GPa, 7.6 MPa m1/2, and 334.5 MPa, respectively. In contrast, the composite of Si3N4–30 vol% ZrB2 simultaneously possessed an excellent combination of mechanical properties: 19.5 GPa in hardness, 9.8 MPa m1/2 in toughness and 702.0 MPa in strength. Present study suggested that Si3N4‐based ceramics with high hardness, high toughness, and high strength could be obtained by the combination of appropriate ZrB2 content and low hot‐pressing temperature. 相似文献
16.
Si3N4/TiC纳米复合陶瓷刀具材料氧化行为 总被引:1,自引:0,他引:1
在微米Si3N4基体中加入纳米Si3N4及TiC颗粒,以Al2O3和Y2O3作为助烧结剂,通过热压烧结制备了Si3N4/TiC纳米复合陶瓷刀具材料,研究了该材料在800~1 250℃时的氧化行为.结果表明:该类材料的氧化特性符合抛物线规律;随TiC含量的增加,材料的抗氧化性能降低.由氧化后样品的X射线衍射谱分析可知:氧化表面生成SiO2和TiO2,表面仅余微量的Si3N4和TiC成分,表明经1 250℃,100h氧化后,样品表面几乎被氧化物覆盖.Si3N4/TiC(含有10%纳米Si3N4和15%TiC,质量分数)纳米复合材料在经过900℃,100h氧化后,其强度无明显下降;但经过1000℃,100h的氧化后,材料的强度已经降至氧化前的41%.扫描电镜观察表明裂纹的生成及扩展是引起强度降低的主要原因. 相似文献
17.
Tsukaho Yahagi Daisuke Kawai Takuma Takahashi Motoyuki Iijima Junichi Tatami 《Journal of the American Ceramic Society》2022,105(3):2046-2057
Si3N4 ceramics with excellent mechanical properties are used for heat dissipation substrates and so on. In order to improve their reliability and expand their application fields, it is desirable to understand and control the electrical properties of Si3N4 ceramics. In this study, the electrical resistivity of Si3N4 ceramics with Yb2O3 additive was investigated by applying various voltages at temperatures ranging from 25°C to 300°C. When Yb2O3 was added as a sintering aid to Si3N4 ceramics, a crystalline J-phase (Yb4Si2O7N2) was formed and their electrical resistivity was significantly lower than that of Y2O3 additive. The electrical resistivity of the Yb2O3-added ceramics decreased with an increase in temperature and applied voltage. Yb existed in multiple valence states, Yb2+ and Yb3+, in the Si3N4 ceramics and the decrease in the electrical resistivity can be attributed hopping conduction through the J-phase. The J-phase in the Si3N4 ceramics was observed to be continuous, and percolation analysis suggested that the J-phase formed an infinite cluster. Therefore, the decrease in the electrical resistivity of the Yb2O3-added Si3N4 ceramics was found mainly to result from the formation of an infinite cluster of J-phase, which exhibits hopping conduction. 相似文献
18.
多孔Si3N4-SiO2复相陶瓷及其性能 总被引:1,自引:0,他引:1
采用近净尺寸成型制备工艺-氧化烧结结合溶胶浸渍再烧结法,制备了多孔Si3N4-SiO2复相陶瓷.讨论了制各工艺对材料的成分、微结构和性能的影响规律.研究表明:随着硅溶胶浸渍量的增加,材料的抗弯强度、硬度、断裂韧性、密度和介电常数均增大.分别采用压痕法和单边切口梁法对材料的断裂韧性进行了测定和比较.结果表明:采用压痕法测定断裂韧性时,多孔Si3N4-SiO2复相陶瓷的增韧机理有裂纹偏转、裂纹分叉、裂纹桥接以及孔的钝化.采用单边切口梁法测定断裂韧性时,多孔Si3N4-SiO2复相陶瓷的增韧机理只有裂纹偏转. 相似文献
19.
Ramakrishna T. Bhatt 《Journal of the American Ceramic Society》1992,75(2):406-412
The room-temperature mechanical properties of a SiC-fiberreinforced reaction-bonded silicon nitride composite were measured after 100 h treatment in nitrogen and oxygen environments to 1400°C. The composite heat-treated in nitrogen to 1400°C showed no appreciable loss in properties. In contrast, composites heat-treated in oxygen from 600° to 1000°C retained ∼65% and 35% of the matrix fracture and ultimate strength, respectively, of the as-fabricated composites, and those heat-treated from 1200° to 1400°C retained greater than 90% and 65% of the matrix fracture and ultimate strength, respectively, of the as-fabricated composites. For all nitrogen and oxygen treatments, the composite displayed strain capability beyond the matrix fracture strength. Oxidation of the fiber surface coating, which caused degradation of bond between the fiber and matrix and reduction in fiber strength, appears to be the dominant mechanism for property degradation of the composites oxidized from 600° to 1000°C. Formation of a protective silica coating at external surfaces of the composites at and above 1200°C reduced oxidation of the fiber coating and hence degrading effects of oxidation on their properties. 相似文献
20.
表面改性处理的纳米Si3N4粉体与聚苯硫醚(PPS)熔融共混挤出制成PPS/纳米Si3N4复合材料,通过拉伸、冲击实验及动态力学性能测试考察了纳米粉体加入量对复合体系各项性能的影响。结果表明,纳米Si3N4填充PPS基复合材料的力学性能明显优于纯PPS。随粉体添加量的增加,复合材料的拉伸强度增大,当添加量为0.8 %时,拉伸强度提高了22 %。随粉体添加量的增加,复合体系冲击强度增大,当粉体添加量为1.2 %时,冲击强度和缺口冲击强度出现最大值,分别比纯PPS增加了33 %和41 %。动态力学性能测试表明,随粉体添加量的增加,PPS分子链段松弛所需能量增加,松弛过程增长,体系储能模量降低,损耗模量增加。 相似文献