Journal of Earth Science
·
2026
·Vol. 37
·期 4
·1584-1593
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IF 4.8
Zhang Jingyi,Huang Shengxuan,Qin Shan,Chariton Stella,Prakapenka Vitali B.,Chen Bin
Most nitrogen is predicted to reside in the Earth’s interior and could be in the form of nitrides. In this study, the chemical reaction of Si 3 N 4 with SiO 2 was explored up to 50 GPa and 2 600 K using laser-heated diamond anvil cells combined with synchrotron radiation X-ray diffraction. The experimental results demonstrate that Si 3 N 4 does not react with SiO 2 and cubic γ-Si 3 N 4 remains stable at extreme pressure and temperature. First-principles calculations were performed to investigate the chemical stability of Si 3 N 4 with the SiO 2 -MgO assemblage, showing that Si 3 N 4 can coexist with Mg 2 SiO 4 and MgSiO 3 polymorphs. Based on our thermal equation of state of cubic γ-Si 3 N 4 , we suggest that cubic γ-Si 3 N 4 is denser than the upper mantle but less dense than the lower mantle. The formation of Si 3 N 4 in the early Earth may contribute to the nitrogen preservation in the deep mantle soon after crystallization of the mantle and Si 3 N 4 is likely a precursor of nitrogen hosts in the modern deep Earth.
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Materials
·
2025
·Vol. 18
·期 17
·4071
·
IF 3.2
Jialin Bai,Xiumin Yao,Xuejian Liu,Zhengren Huang
SiC nanowires (SiCnw), due to their excellent dielectric properties, are promising high-temperature absorbing materials. However, the mechanism of their high-temperature absorption still requires further research. Therefore, porous SiCnw/Si3N4and SiC/Si3N4ceramics with different SiC phase morphologies were fabricated using a simple precursor impregnation and pyrolysis method. The Fe impurity content of the Si3N4powder raw material significantly affects the generation of SiC nanowires. When SiC exists in the form of nanowires, the excellent conductivity brought by the conductive network of the nanowires causes a significant response of the material’s permittivity to temperature. When the test temperature is room temperature, SiCnw/Si3N4has excellent absorption performance with a minimum reflection loss of −29.75 dB at 2.16 mm and an effective absorption bandwidth of 3.72 GHz at 2.54 mm. As the test temperature increases to 300 °C, the effective absorption bandwidth of SiCnw/Si3N4covers the entire X-band. The porous SiCnw/Si3N4ceramics exhibit excellent electromagnetic wave absorption performance, demonstrating significant application potential for high-temperature environments.
研究领域:
材料科学
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无机非金属材料
·
功能陶瓷
·
电磁波吸收
·
高温材料
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高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2026
·
IF 5.2
Donglin Lu,Yuqin Shen,Zibin Zeng,Bocong Feng,Haidong Wu,Huachen Cui,Shanghua Wu
In this study, a novel inorganic surface modification strategy was proposed by coating silicon nitride (Si 3 N 4 ) powders with potassium chloride (KCl) to enhance their optical and rheological behavior for high-precision digital light processing (DLP) additive manufacturing. The influence of KCl coating content (0–8 wt%) on the photopolymerization, rheological properties, densification behavior, microstructure, and mechanical performance of Si 3 N 4 ceramics was systematically investigated. The results revealed that molten KCl at 900 °C effectively wet and redistributed on the Si 3 N 4 surface, forming a uniform KCl/SiO 2 composite coating. This coating reduced the refractive index mismatch at the particle–resin interface, suppressed Mie scattering, and significantly increased the curing depth while minimizing lateral over-curing. The optimal coating condition (3 wt% KCl, 900 °C, 5 h) achieved enhanced curing depth, improved slurry flowability, and stable dispersion without excessive agglomeration. However, excessive coating (≥ 5 wt%) intensified surface oxidation and led to Si 2 N 2 O formation, resulting in porous microstructures and severely reduced mechanical strength. The bending strength declined from 697 MPa (0 wt%) to 97 MPa (8 wt%). By contrast, the 3 wt% KCl-coated powder yielded Si 3 N 4 components with relatively high density, smooth surfaces, and excellent dimensional fidelity after sintering. These findings demonstrate that ionic-salt coatings offer a controllable and scalable approach to tuning light–matter interactions and interfacial behavior in ceramic slurries, paving the way for the additive manufacturing of complex Si 3 N 4 structures with superior precision.
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CERAMICS INTERNATIONAL
·
2024
·Vol. 51
·期 1
·798-804
·
IF 5.1
Yuanhang Zheng,Yun Liu,Ruixiang Liu,Xuemei Yan,Tianyi Sui,Xiaolei Li,Bin Lin
In recent years, porous Si 3 N 4 ceramics have been recognized as the most promising materials for radomes. In this study, porous Si 3 N 4 ceramics with excellent mechanical properties have been successfully prepared by adding 2 wt% Lu 2 O 3 , of which the effect of sintering temperature on the grain growth mechanism is investigated for microstructure tailoring. When sintered at 1720 °C, the lower liquid viscosity allows the grain growth rate to match with dissolution-precipitation process. Through this process, the grains further grew together to form a more homogeneous rod-like structure, resulting in a more concentrated aspect ratio and particle size distribution . In addition, the grains along the c-axis grew faster due to the Lu 3+ ions, resulting in a higher aspect ratio. However, when further increased to 1750 °C, the viscosity of the liquid decreases significantly, leading to the precipitation of a large number of β-Si 3 N 4 nuclei. Due to the combined effect of the steric hindrance and the liquid phase mainly distributed at the ends of the grains, a short and thick morphology with a thick center and fine ends is formed, which is unfavorable to the bending strength . Therefore, when the porosity of the sample at 1720 °C is 64.5 %, the bending strength can still reach 162 MPa with a structure factor of 2.82.
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CERAMICS INTERNATIONAL
·
2026
·
IF 6
Hongli Liu,Weiqiang Xie,Chengzhe Liu,Peng Chu,Yuhao Liu,Zhihang Yu,Kaibin Yang,Wenshuo Cao,Mingwei Li,Xianlin Xiao,Jianwei Jia
Silicon nitride (Si 3 N 4 ) ceramic nanofibers are promising candidates for high-temperature thermal insulation due to their high fracture toughness, excellent thermal stability, and superior creep resistance. However, their vulnerability to oxidative corrosion in oxygen-rich environments at elevated temperatures can severely degrade mechanical integrity and thermal stability, thereby limiting practical deployment. To address this, this study proposes a core-shell architectural design strategy. Composite precursor fibers were produced by coaxial electrospinning using a polysilazane (PSZ)-based core solution and a shell dispersion containing yttrium oxide (Y 2 O 3 ) particles, followed by pyrolysis at 1400 °C to yield Si 3 N 4 /Y 2 O 3 core-shell ceramic nanofibers. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirm the formation of a well-defined core-shell structure featuring a dense surface composite layer composed of Y 2 Si 2 O 7 /Si 2 N 2 O/Y 2 O 3 , which substantially enhances high-temperature oxidation resistance. Mechanistic insights derived from combined XRD, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and post-oxidation characterization indicate that oxidation proceeds via limited initial reactions, followed by partial oxidation of Si 2 N 2 O to generate molten SiO 2 at high temperatures. This highly fluid SiO 2 phase can migrate and spread over the fiber surface, dynamically sealing pores and microcracks, thereby establishing an effective oxygen-diffusion barrier with an intrinsic self-healing function. As a result, the materials exhibit exceptional integrated properties: high-temperature thermal conductivity remains stable at 0.385-0.404 W·m -1 ·K -1 at 1300 °C; oxidation resistance is remarkable, with only 2.91 % mass loss after 2 h at 1400 °C in air; and the fibrous mats retain excellent mechanical flexibility. Overall, the Si 3 N 4 /Y 2 O 3 core-shell structural design enables a synergistic enhancement of oxidation resistance while preserving thermal insulation and flexibility, offering a viable strategy for next-generation ultrahigh-temperature insulation materials.
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International Journal of Applied Ceramic Technology
·
2022
·Vol. 20
·期 3
·1855-1864
·
IF 2.328
Shi Fu,Zengchao Yang,Honghua Li,Liang Wang,Yong Li,Jiangtao Li
Si 3 N 4 ceramics were prepared by gas pressure sintering at 1900°C for 12 h under a nitrogen pressure of 1 MPa using Gd 2 O 3 and MgSiN 2 as sintering additives. The effects of the Gd 2 O 3 /MgSiN 2 ratio on the densification, microstructure, mechanical properties, and thermal conductivity of Si 3 N 4 ceramics were systematically investigated. It was found that a low Gd 2 O 3 /MgSiN 2 ratio facilitated the thermal diffusivity of Si 3 N 4 ceramics while a high Gd 2 O 3 /MgSiN 2 ratio benefited the densification and mechanical properties. When the Gd 2 O 3 /MgSiN 2 ratio was 1:1, Si 3 N 4 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·m 1/2 , respectively. Comparing with the results in the literature, it was shown that Gd 2 O 3 -MgSiN 2 was an effective additives system for obtaining Si 3 N 4 ceramics with high thermal conductivity and superior mechanical properties.
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International Journal of Applied Ceramic Technology
·
2022
·Vol. 19
·期 6
·3403-3409
·
IF 2.328
Minzhong Huang,Yao Huang,Jun Ou,Yangyang Wu,Junye Wang,Shanghua Wu
Enhancement of the thermal conductivity of silicon nitride is usually achieved by sacrificing its mechanical properties (bending strength). In this study, β-Si 3 N 4 ceramics were prepared using self-synthesized Y 3 Si 2 C 2 and MgO as sintering additives. It was found that the thermal conductivity of the Si 3 N 4 ceramics was remarkably improved without sacrificing their mechanical properties. The microstructure and properties of the Si 3 N 4 ceramics were analyzed and compared with those of the Y 2 O 3 -MgO additives. The addition of Y 3 Si 2 C 2 eliminated the inherent SiO 2 and introduced nitrogen to increase the N/O ratio of the grain-boundary phase, inducing Si 3 N 4 grain growth, increasing Si 3 N 4 grain contiguity, and reducing lattice oxygen content in Si 3 N 4 . Therefore, by replacing Y 2 O 3 with Y 3 Si 2 C 2 , the thermal conductivity of the Si 3 N 4 ceramics was significantly increased by 31.5% from 85 to 111.8Wm −1 K −1 , but the bending strength only slightly decreased from 704 ± 63MPa to 669 ± 33MPa.
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CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Qiang Zhi,Bo Wang,Shan Zhao,Zhao Zhang,Yu-Chen Deng,Bao-Qiang Hou,Nan-Long Zhang,Jian-Feng Yang
Si 3 N 4 ceramic with ultrafine fibrous grains are expected to exhibit remarkable mechanical properties . In this work, highly porous Si 3 N 4 ceramic monoliths composed of ultrafine fibrous grains were developed via a novel vapor-solid carbothermal reduction nitridation (V-S CRN) reaction between SiO vapor and green bodies comprised of carbon nanotubes (CNTs), α-Si 3 N 4 diluents and Y 2 O 3 in a N 2 atmosphere. The unique fibrous grains-interconnected structure was developed through in-situ formation of Si 3 N 4 and following liquid phase sintering . The porous Si 3 N 4 monoliths with porosity of 61–78% was developed by controlling the contents of α-Si 3 N 4 diluents and densities of the CNT green bodies. With increasing of the α-Si 3 N 4 contents, Si 3 N 4 fibrous grains with an aspect ratio of approximate or higher than 20 could be achieved, and the grains were gradually refined. For the samples with 40 wt% α-Si 3 N 4 , the minimum mean grain diameter and pore size of 164 nm and 0.79 μm were achieved, respectively, and the resultant porous Si 3 N 4 monolith exhibited a flexural strength of as high as 73–102 MPa with the porosity of 61–73%, which is much higher than that of the reported in literature. The improvement of mechanical strength could be attributed to the densely interconnected bird's nests structure formed by the ultrafine fibrous grains. The effects of the α-Si 3 N 4 diluents on the resulting porous Si 3 N 4 monolith via this method were analyzed.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 103
·期 10
·5567-5572
·
IF 3.502
Weide Wang,Dongxu Yao,Hanqin Liang,Yongfeng Xia,Kaihui Zuo,Jinwei Yin,Yu-Ping Zeng
A two-step sintering process was conducted to produce β-Si 3 N 4 ceramics with high thermal conductivity. During the first step, native SiO 2 was eliminated, and Y 2 O 3 was in situ generated by a metal hydride reduction process, resulting in a high Y 2 O 3 /SiO 2 ratio. The substitution YH 2 for Y 2 O 3 endow Si 3 N 4 ceramics with an increase of 29% in thermal conductivity from 95.3 to 123 W m −1 K −1 after sintered at 1900°C for 12 hours despite an inferior sinterability. This was primarily attributed to the purified enlarged grains, devitrified grain boundary phase, and reduced lattice oxygen content in the YH 2 -MgO-doped material.
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ACS Applied Materials & Interfaces
·
2023
·
IF 9.5
Shiqin Wan,Xu Hao,Lifeng Zhu,Chang Yu,Mengyi Li,Zheng Zhao,Jianlei Kuang,Ming Yue,Qipeng Lu,Wenbin Cao,Qi Wang
As the rapid development of advanced foldable electronic devices, flexible and insulating composite films with ultra-high in-plane thermal conductivity have received increasing attention as thermal management materials. Silicon nitride nanowires (Si3N4NWs) have been considered as promising fillers for preparing anisotropic thermally conductive composite films due to their extremely high thermal conductivity, low dielectric properties, and excellent mechanical properties. However, an efficient approach to synthesize Si3N4NWs in a large scale still need to be explored. In this work, large quantities of Si3N4NWs were successfully prepared using a modified CRN method, presenting the advantages of high aspect ratio, high purity, and easy collection. On the basis, the super-flexible PVA/Si3N4NWs composite films were further prepared with the assistance of vacuum filtration method. Due to the highly oriented Si3N4NWs interconnected to form a complete phonon transport network in the horizontal direction, the composite films exhibited a high in-plane thermal conductivity of 15.4 W·m–1·K–1. The enhancement effect of Si3N4NWs on the composite thermal conductivity was further demonstrated by the actual heat transfer process and finite element simulations. More significantly, the Si3N4NWs enabled the composite film presenting good thermal stability, high electrical insulation, and excellent mechanical strength, which was beneficial for thermal management applications in modern electronic devices.
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高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Miao Zhou,Yun Liu,Xiaolei Li,Tianyi Sui,Dong Su,Huiming Ji
Silicon nitride (Si 3 N 4 ) ceramics were prepared by gas-pressure sintering using Y 2 O 3 –MgSiN 2 as a sintering additive. The densification behavior, phase transition, and microstructure evolution were investigated in detail, and the relevance between the microstructure and the performance (including thermal conductivity and mechanical properties) was further discussed. A significant change from a bimodal to a homogeneous microstructure and a decreased grain size occurred with increasing Y 2 O 3 –MgSiN 2 content. When the small quantity of preformed β-Si 3 N 4 nuclei grew preferentially and rapidly in a short time, an obvious bimodal microstructure was obtained in the sample with 4 mol% and 6 mol% Y 2 O 3 –MgSiN 2 . When more β-Si 3 N 4 nuclei grew at a relatively rapid rate, the sample with 8 mol% Y 2 O 3 –MgSiN 2 showed a microstructure consisting of numerous abnormally grown β-Si 3 N 4 grains and small grains. When more β-Si 3 N 4 nuclei grew simultaneously and slowly, there was a homogeneous microstructure and smaller grains in the sample containing 10 mol% Y 2 O 3 –MgSiN 2 . Benefitting from the completely dense, significant bimodal microstructure, low grain boundary phase, and excellent Si 3 N 4 –Si 3 N 4 contiguity, the sample containing 6 mol% Y 2 O 3 –MgSiN 2 exhibited great comprehensive performance, with a maximum thermal conductivity and fracture toughness of 84.1 W/(m⋅K) and 8.97 MPa m 1/2 , as well as a flexural strength of 880.2 MPa.
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高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Guandong Liang,Jianqiang Bi,Linjing Qiao,Shaoyin Wang,Yao Yang,Zhuangzhuang Yin
In view of the lack of a conformal, load-bearing, lightweight, and high-temperature resistant integrated microwave-absorbing composites for applications under extremely complex conditions, this study successfully applies gel casting craft to porous Si 3 N 4 microwave-absorbing composites. The high-temperature decomposition reaction of Ti 3 SiC 2 powder was utilized to generate uniform Ti-C x -N 1−x grains in situ and to enhance the mechanical and microwave-absorption properties of porous Ti-C x -N 1−x /Si 3 N 4 composites. The bending strength , fracture toughness, density, maximum reflection loss value, absorption bandwidth and matched thickness in P-band of the composite with 30 wt% Ti 3 SiC 2 addition were 164.87 ± 7.56 MPa, 2.61 ± 0.13 MPa·m 1/2 , 2.077 g/cm 3 , 32.42 dB, 1.74 GHz and 4.2 mm, respectively. The fracture toughness and bending strength of the composite were increased by 71.71% and 58.13%, respectively, compared with monolithic porous Si 3 N 4 . The electromagnetic wave loss mechanisms of the composites are proposed as a combination of conductivity loss, multiple reflections and scattering, interfacial polarization and defect polarization.
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