CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Zunlan Hu,Yiyao Ge,Jian Liu,Zhipeng Xie
In this paper, α-Si 3 N 4 nanobelts assembled by Si 3 N 4 microcrystals on the nanowires were synthesized from amorphous Si 3 N 4 powders that were prepared by thermolysis of silicon diimide powders. By prolonging the heating time at 1550 °C, the amorphous Si 3 N 4 powders were converted to hexagonal phase α-Si 3 N 4 microcrystals which were adhered to the surface of nanowires to obtain α-Si 3 N 4 nanobelts. The obtained α-Si 3 N 4 nanobelts were hollow in the centre with a width of ∼850 nm and a thickness of ∼150 nm. Microcrystals were deposited on the surface of 2–3 parallel nanowires. The diameter of the Si 3 N 4 microcrystals was 30–230 nm, and the diameter of the nanowires was 50–100 nm. Evaporation of the amorphous Si 3 N 4 powders released Si vapour and N vapour, which led to the formation of the Si 3 N 4 microcrystals. The nanowires grew on the surface of the amorphous Si 3 N 4 powders due to the nucleation and diffusion of Si and N atoms of amorphous Si 3 N 4 powders. The growth mechanism of the products with unique morphology can be considered as a combination of vapour-solid mechanism and secondary nucleation process.
研究领域:
材料科学
·
纳米技术
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产品关联
DOI
高影响因子
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
·
2019
·
IF 3.176
Zunlan Hu,Wenlong Huo,Tianbin Zhu,Jian Liu,Zhipeng Xie
In this paper, a new nanomaterial , α-Si 3 N 4 nanobelts assembled by high density nanorods were prepared via the crystallization of amorphous Si 3 N 4 at 1450 °C for 12 h. The as-synthesized nanobelts exhibited a width of ∼900 nm and a thickness of ∼150 nm, and a depressed linear region in the central. α-Si 3 N 4 nanorods on the nanobelts had a width of 8–16 nm and a length of 400–450 nm. The nanorods were single-crystal, growing along (101) plane. The nanobelt appeared to be initiated by α-Si 3 N 4 nanorods constantly growing on the both sides of a nanowire which was caused by secondary nucleation and the growth of Si 3 N 4 microcrystals . Growth mechanism related to the formation of the nanobelts was analyzed in detail on the basis of vapor-solid mechanism and secondary nucleation. The current work would provide new insights into α-Si 3 N 4 nanobelts assembled by nanorods which play an important role in nanoscale devices and show widespread potential applications due to their special morphology.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Zunlan Hu,Jian Liu,Zhipeng Xie
Silicon nitride (Si 3 N 4 ) particles with different morphologies have been used in many fields. In this work, α-Si 3 N 4 whiskers and granular particles with high-phase purity were successfully tailored by the controllable crystallisation process of amorphous Si 3 N 4 powders under different N 2 pressure. Impressively, α-Si 3 N 4 whiskers were prepared by simply heat treating amorphous Si 3 N 4 powders at 1550 °C for 2 h under the low N 2 pressure of 0.2 MPa, whereas equiaxed α-Si 3 N 4 particles with uniform size of ~280 nm were obtained under an elevated N 2 pressure of 2.0 MPa. With the evaluated N 2 pressures and temperatures, large scale α-Si 3 N 4 whiskers or equiaxed α-Si 3 N 4 particles could be produced. The growth mechanisms of the α-Si 3 N 4 particles with distinct morphologies were rationally proposed, and these consist of two main growth processes. First, amorphous Si 3 N 4 powders decomposed into Si(g) and N 2 (g) under high-temperature treatment. Subsequently, N 2 (g) dominated the recombination of the evaporated chemical with the Si 3 N 4 molecule. The initial N 2 concentration, which plays a key role in tailoring the shape and size of products, was controlled by the N 2 pressure.
研究领域:
材料科学
·
无机化学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Chao Wang,Xu Wang,Binglei Wang,Guozheng Xiao,Ruiqing Qiao,Fan Zhang,Yu Bai,Yizhuo Li,Yusheng Wu,Zhanjie Wang,Hongjie Wang
A dense β-Si 3 N 4 coating toughened by β-Si 3 N 4 nanowires/nanobelts was prepared by a combined technique involving chemical vapor deposition and reactive melt infiltration to protect porous Si 3 N 4 ceramics in this work. A porous β-Si 3 N 4 nanowires/nanobelts layer was synthesized in situ on porous Si 3 N 4 ceramics by chemical vapor deposition, and then Y–Si–Al–O–N silicate liquid was infiltrated into the porous layer by reactive melt infiltration to form a dense composite coating . The coating consisted of well-dispersion β-Si 3 N 4 nanowires/nanobelts, fine β-Si 3 N 4 particles and small amount of silicate glass . The testing results revealed that as-prepared coating displayed a relatively high fracture toughness, which was up to 7.9 ± 0.05 MPa m 1/2 , and it is of great significance to improve thermal shock resistance of the coating. After thermal cycling for 15 times at ΔT = 1200 °C, the coated porous Si 3 N 4 ceramics still had a high residual strength ratio of 82.2%, and its water absorption increased only to 6.21% from 3.47%. The results will be a solid foundation for the application of the coating in long-period extreme high temperature environment.
研究领域:
材料科学
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表面工程
✓ 已验证
DOI
高影响因子
Gels
·
2025
·Vol. 11
·期 5
·324
·
IF 5.3
Zongwei Tong,Xiangjie Yan,Yun Liu,Yali Zhao,Kexun Li
Traditional nanoparticle aerogels suffer from inherent brittleness and thermal instability at elevated temperatures. In recent years, ceramic nanofiber aerogels, utilizing flexible nanofibers as structural units, have emerged as mechanically resilient alternatives with ultrahigh porosity (>90%). However, their thermal insulation capabilities are compromised by micron-scale pores (10–100 μm) and overdependence on ultralow density, which exacerbates mechanical fragility. This study pioneers a gas-phase self-assembly strategy to fabricate Si3N4nanoparticle reinforced Si3N4nanofiber aerogels (SNP-R-SNFA) with gradient pore architectures. By leveraging methyltrimethoxysilane/vinyltriethoxysilane composite aerogel (MVa) as a reactive template, we achieved spontaneous growth of Si3N4nanofiber films (SNP-R-SNF) featuring nanoparticle-fiber interpenetration and porosity gradients. The microstructure formation mechanism of SNP-R-SNF was analyzed using field-emission scanning electron microscopy. Layer assembly and hot-pressing composite technology were employed to prepare the SNP-R-SNFA, which showed low density (0.033 g/cm3), exceptional compression resilience, insensitive frequency dependence of dielectric properties (ε′ = 2.31–2.39, tan δ < 0.08 across 8–18 GHz). Infrared imaging displayed backside 893 °C cooler than front, demonstrating superior insulation performance. This study not only provides material solutions for integrated electromagnetic wave-transparent/thermal insulation applications but more importantly establishes an innovative paradigm for enhancing the mechanical robustness of nanofiber-based aerogels.
研究领域:
材料科学
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纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED POWDER TECHNOLOGY
·
2024
·
IF 4.2
Zunlan Hu,Fangnan Zhao,Zhipeng Xie
A facile procedure was provided to obtain amorphous Si 3 N 4 powder via a liquid-phase method, followed by a heat treatment process to realize tailorable shapes for α-Si 3 N 4 crystal, while Si 3 N 4 granules were synthesized and whiskers were inhibited. The influence of the temperature on the particle morphology and growth mechanisms were investigated. Characterizations indicated that the crystallization temperature played an important role in controlling the morphology of α-Si 3 N 4 powder, while the relatively lowly temperature (below 1519 °C) was beneficial to forming whiskers. The growth of Si 3 N 4 whiskers, derive from the reaction between SiO(g) and N 2 , follows the vapor–solid (VS) mechanism, which is inhibited by the increase in temperature. Instead, higher temperatures were conducive to forming granular structures. Highly crystalline α-Si 3 N 4 granules were prepared at 1550 °C due to Si*(g) and N*(g) recombining to Si 3 N 4 nuclei via the vapor–solid-solid (VSS) mechanism providing a theoretical basis for inhibiting the production of the whiskers.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2024
·
IF 11.2
Qiang Zhi,Shan Zhao,Baoqiang Hou,Nanlong Zhang,Feng Li,Bo Wang,Jianfeng Yang
Highly porous Si 3 N 4 ceramics with unidirectionally aligned pore channels are gaining significant attention across various fields due to their outstanding functional capabilities. However, achieving high strength in such unidirectional highly porous Si 3 N 4 ceramics remains challenging. Herein, we design and fabricate a novel β-Si 3 N 4 scaffold composed of directionally aligned lamellar walls with a textured microstructure by directionally freeze casting of α-Si 3 N 4 suspensions with fine elongated β-Si 3 N 4 seeds addition, followed by liquid phase sintering. During the sintering, the scaffold exhibited anisotropic shrinkage, and fibrous β-Si 3 N 4 grains were synthesized through epitaxial growth on the seeds preferentially oriented or the nuclei originated from α-Si 3 N 4 powders, resulting in the grains aligned parallel to lamellar walls and bridged the walls. Seed additions of 7 to 15 wt% were beneficial for the optimized distribution of the two types of β-Si 3 N 4 grains, which contributed to the excellent resistance to bucking-induced fracture for the walls. Compared with other unidirectional porous Si 3 N 4 prepared by freeze-casting in the literature, the Si 3 N 4 scaffold exhibited outstanding compressive strength, ranging from 2.8 to 22.0 MPa, as the porosity decreased from 94.4% to 88.0% and the density increased from 175 to 365 mg/cm 3 . The lightweight and strong Si 3 N 4 scaffolds are promising candidates for engineering applications in harsh environments.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Guang-Xin Mao,Jia-Min Wu,Chong Tian,Chun-Lei Liu,Xin Lin,Fen Wang,Hai-Sheng Xu,Yu-Sheng Shi
Porous Si 3 N 4 ceramics are widely applied in aerospace and mechanical fields owing to their excellent properties. Furthermore, vat photopolymerization (VPP) technology can fabricate Si 3 N 4 components with complicated structures and high precision, but its layer-by-layer printing method leads to poor mechanical properties of ceramics. In this study, porous Si 3 N 4 ceramics with a porosity of 28.41 % strengthened by directional β-Si 3 N 4 were fabricated by combining VPP technology and seeding method. Rheological behavior and curing properties of the slurry were explored, and the influence of β-Si 3 N 4 content on the mechanical properties of printed Si 3 N 4 ceramics was investigated systematically. With the increase of β-Si 3 N 4 content, the orientation degree of β-Si 3 N 4 grains increased gradually, while fracture toughness and flexural strength of the ceramics exhibited a trend of increased first and then decreased and Vickers hardness gradually decreased. As β-Si 3 N 4 content increased to 5 wt%, the fracture toughness and flexural strength of porous Si 3 N 4 ceramics were improved from 4.23 MPa m 1/2 and 214.7 MPa–5.65 MPa m 1/2 and 272.0 MPa, respectively. Therefore, this work indicates that vat photopolymerization combined with seeding method is a promising approach for the fabrication of porous Si 3 N 4 ceramics with high performance and complex structures.
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Ling Li,Qinggang Li,Juan Hong,Mengyong Sun,Jie Zhang,Shaoming Dong
Porous Si 3 N 4 ceramics with uniform pore distributions were fabricated by freeze drying with liquid N 2 as refrigerant, and then sintered at 1700 °C under an N 2 pressure of 0.3 MPa. The Si 3 N 4 dispersant slurries were prepared by ball milling for 12 h and casting into a mold using liquid nitrogen as a freezing medium with the top surface of the sample exposed to air at room temperature. The temperature gradient contributed to bimodal peaks of pore size distribution . Effects of solid concentration on the porosity, mechanical, and dielectric properties of the Si 3 N 4 sample were systematically investigated. As the solid content increased from 15 vol.% to 40 vol.%, the porosity decreased from 83.9% to 40.58%. Therefore, flexural strength and compressive strength increased from 0.1 MPa to 94.7 MPa, and 1.3 MPa–314 MPa, respectively. Moreover, the dielectric constant increased from 1.4 to 4.0. This study indicated that the freeze-drying process is a useful method for fabricating novel porous Si 3 N 4 ceramics with unidirectional channels.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Changlian Chen,Xin Liang,Maya Luo,Shicong Zhou,Jiayou Ji,Zhiliang Huang,Man Xu
Porous Si 3 N 4 -bonded SiC ceramics with high porosity were prepared by the reaction-sintering method. In this process, Si 3 N 4 was synthesized by the nitridation of silicon powder. The X-ray diffraction (XRD) indicated that the main phases of the porous Si 3 N 4 -bonded SiC ceramics were SiC, α-Si 3 N 4 , and β-Si 3 N 4 , respectively. The contents of β-Si 3 N 4 were increased following the sintering temperature . The morphology of Si 3 N 4 whiskers was investigated by scanning electron microscope (SEM), which was shown that the needle-like (low sintering-temperature) and rod-like (higher sintering-temperature) whiskers were formed, respectively. From low to high synthesized temperature, the highest porosity of the porous Si 3 N 4 bonded SiC ceramic was up to 46.7%, and the bending strength was ~11.6 MPa. The α-Si 3 N 4 whiskers were derived from the reaction between N 2 and Si powders, the growth mechanism was proved by Vapor–Solid (VS). Meanwhile, the growth mechanism of β-Si 3 N 4 was in accordance with Vapor–Solid–Liquid (VSL) growth mechanism. With the increase of sintering temperature, Si powders were melted to liquid silicon and the α-Si 3 N 4 was dissolved into the liquid then the β-Si 3 N 4 was precipitated successfully.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Applied Ceramic Technology
·
2022
·Vol. 19
·期 5
·2533-2544
·
IF 2.328
Changxi Jiang,Yinghua Zhuang,Jianjun Wang,Shengjun Liao,Lijuan Zhou,Shuang Li,Yunxia Zhao
Si 3 N 4 ceramics with high thermal conductivity and outstanding mechanical properties were prepared by adding β-Si 3 N 4 seeds and nanophase α-Si 3 N 4 powders as modifiers. The introduction of β-Si 3 N 4 seeds enhanced the growth of β-Si 3 N 4 grains. Owing to the interlocked structure induced by the β-Si 3 N 4 grains, the fracture toughness of Si 3 N 4 ceramics reached a high value of 7.6 MPa·m 1/2 ; also, the large-sized grains increased the contact possibility of Si 3 N 4 grains, improving the thermal conductivity of Si 3 N 4 ceramics (64 W/(m·K)). Because of the introduction of nanophase α-Si 3 N 4 , the flexural strength, fracture toughness, and thermal conductivity of the Si 3 N 4 ceramics increased to 754 MPa, 7.2 MPa·m 1/2 , and 54 W/(m·K), respectively. According to the analysis of the growth kinetics of Si 3 N 4 grains, the rapid growth of Si 3 N 4 grains was ascribed to the reduction in the activation energy resulting from the introduction of β-Si 3 N 4 seeds and nanophase α-Si 3 N 4 .
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Chaochen Chen,Fang Lei,Ying Shi,Jianjun Xie,Lei Zhang,Lingcong Fan
The surface metallization of Si 3 N 4 ceramics with the Ag–Cu conductive paste containing CuO was systematically investigated. The interfacial reactions between CuO and Si 3 N 4 promoted the surface metallization of the ceramic substrate in an argon atmosphere. The effects of Ag and Cu relative contents on the evolution of the thick film surface morphology were studied. The electrical properties and tensile strength of composite ceramic substrates were enhanced through the generation of Ag–Cu eutectic solution within the thick film layer. The effect of brazing time on the properties of Ag–Cu/Si 3 N 4 composite ceramic substrates was investigated. Mechanical testing and scanning electron microscopy (SEM) were used to analyze the interface tensile strength of the Ag–Cu/Si 3 N 4 composite substrates and the morphology of the Ag–Cu film, and the bonding mechanism of the composite ceramic substrate was studied. When the sample was brazed at 800 °C for 20 min, the maximum tensile strength of 23.6 MPa between the Ag–Cu film and ceramic substrate was obtained, the lowest resistivity of 6.22 μΩ•cm was obtained. The bonding interface between thick film layer and the ceramic substrate formed the Ag–Cu mechanical structure was benefit for improving the comprehensive performance of the Cu/Si 3 N 4 composite ceramic substrate.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）