Journal of Materials Research and Technology-JMR&T
·
2023
·
IF 6.4
Pengfei Li,Ruiming Yin,Yunfei Bai,Yanhong Ding,Xiaofeng Zeng,Yongquan Li
To reduce the lattice oxygen content of Si 3 N 4 green bodies, samples were prepared using an N,N-dimethylacrylamide (DMAA) system. The endothermic and exothermic peaks are related to the decomposition of organic matter and the reaction between pyrolytic carbon and impurity oxides in the sintering process. Multi-step heat preservation during the thermal degreasing process reduced the carbon content and defects. The α→β phase transformation and aspect ratio of grains changed from 89.2% to 4.84:1 at 1640 °C to 96.3% and 7.80:1 at 1700 °C, respectively. The relative density, hardness, fracture toughness, and thermal conductivity of the Si 3 N 4 samples reached 98.5%, 1353 HV, 8.51 MPa·m 1/2 , and 97.1 W·m −1 ·K −1 , respectively. Pyrolytic carbon can react with SiO 2 , which reduces the content of the glass phase in the green body and affects the dissolution and precipitation process and lattice oxygen content. In the structure of the Si 3 N 4 sample, carbon particles with sizes of 100–500 nm and near-spherical shapes were observed. Intergranular-phase YMgSi 2 O 5 N was formed during the sintering process, which was conducive to improving the thermal conductivity. This article uses lower temperature and no pressure conditions to prepare Si 3 N 4 ceramics, which can provide reference for batch and low-cost production.
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
JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Weide Wang,Dongxu Yao,Hanqin Liang,Yongfeng Xia,Kaihui Zuo,Jinwei Yin,Yu-Ping Zeng
This work reports the two-step sintering method and thermal conductivity of Si 3 N 4 doped with 1.5 wt% MgO and varied contents of ZrH 2 in the range of 0-5 wt%. The metal hydride reduction reaction in the first step sintering allows the in situ generations of ZrO 2 and the elimination of native SiO 2 . A smaller amount of liquid phase with reduced oxygen content was produced during the second step sintering as a result of the replacement of ZrO 2 by ZrH 2 . With the aid of ZrH 2 as an oxygen getter, the native oxygen in those ZrH 2 -doped samples was removed via a route of SiO 2 →ZrO 2 →SiO(g). Consequently, the densified Si 3 N 4 ceramics with larger volume percent of elongated purified β-Si 3 N 4 grains and less glassy phase were obtained. Ultimately, the optimal thermal conductivity of 116.4 W m −1 K −1 was achieved after sintered at 1900 °C for 12 h by using 3 wt% ZrH 2 and 1.5 wt% MgO as additives.
研究领域:
材料科学
·
热物理
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Weide Wang,Dongxu Yao,Hanqin Liang,Yongfeng Xia,Kaihui Zuo,Jinwei Yin,Yu-Ping Zeng
The effect of the GdH 2 on the shrinkage behavior, microstructure, thermal conductivity , and flexural strength was investigated. The pre-sintering enables the elimination of native SiO 2 and the simultaneous formation of Gd 2 O 3 . The N/O ratio in the liquid phase was increased because of the increasing Gd 2 O 3 /SiO 2 ratio, resulting in the restricted shrinkage during gas pressure sintering. The high N/O ratio in the liquid phase benefits not only the nucleation and growth of β-Si 3 N 4 but also the removal of lattice oxygen, leading to the increase of thermal conductivity . Although the replacement of Gd 2 O 3 by GdH 2 leads to enhanced flexural strength at low temperature, it tends to reduce the flexural strength at high temperature. This variation related largely to the exaggerated bimodal microstructure. This work signifies that GdH 2 is an effective sintering additive for obtaining Si 3 N 4 ceramics with both high flexural strength and high thermal conductivity.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Xuanzhi Chen,Yehua Li,Youwu Liu,Pengjin Huang,Haidong Wu,Shanghua Wu,Xin Deng
Si 3 N 4 ceramics were sintered at 1850 °C and 2 MPa in a nitrogen atmosphere, using Gd 3 Si 2 C 2 -MgO as a sintering aid. The impact of Gd 3 Si 2 C 2 content and sintering dwell time at 1850 °C on the relative density, microstructure, and thermal conductivity of the Si 3 N 4 ceramics was investigated. The results indicate that under 4 h of sintering, increasing Gd 3 Si 2 C 2 content significantly enlarges Si 3 N 4 grain size while reducing microstructural uniformity; however, after 8 h, grain size refines and uniformity markedly improves. This phenomenon is mainly attributed to the increase in Gd 3 Si 2 C 2 content, which raises the number of β-Si 3 N 4 nucleation sites, thereby facilitating grain growth during short-term sintering; whereas during long-term sintering, the further enlarged grains generate a spatial hindrance effect, promoting the homogenization of the microstructure. Furthermore, under the same Gd 3 Si 2 C 2 content, extending the sintering time is beneficial to the growth of silicon nitride grains and the reduction of the glass phase, enhancing the continuity of Si 3 N 4 /Si 3 N 4 interfaces and thereby improving the thermal conductivity of Si 3 N 4 ceramics. The maximum thermal conductivity of 107.25 W·m −1 ·K −1 was achieved with a Gd 3 Si 2 C 2 content of 1 mol% and a sintering period of 8 h at 1850 °C.
研究领域:
材料科学
·
陶瓷
·
热性能
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Ning Sun,Tengpeng Wang,Yuhang Du,Xiaojun Ma,Wenkai Xin,Haochen Dang,Xuqiu Xie,Tao Wei,Qinggang Li
Si 3 N 4 ceramics pose a challenge when it comes to the preparation of light-curing pastes with high depth of cure, elevated solid content, and low viscosity. This challenge is primarily attributed to their inherent characteristics, including high absorbance, a high refractive index, and suboptimal sphericity. Consequently, the application of Si 3 N 4 ceramics in 3D printing remains a complex endeavor. To address the intricacies associated with 3D printing using Si 3 N 4 ceramics, our research focuses on the utilization of Tetramethylammonium Hydroxide (TMAH) for pH adjustment in Si 3 N 4 ceramics. This adjustment aims to enhance the stability, curing depth, and viscosity of the slurry. Subsequently, we employ this Si 3 N 4 light-curing slurry for 3D printing, followed by sintering the printed materials. The evaluation includes testing for porosity, density, and flexural strength of the samples. Notably, our efforts yield porous silicon nitride ceramics boasting an impressive density of 1.8299 g/cm 3 , porosity measuring 43.718%, and remarkable flexural strength amounting to 275 MPa.
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
Materials Today Communications
·
2024
·
IF 3.7
Gaoxi Cui,Tongyang Li,Ziyue Wang,Lujie Wang,Yuan Yu,Huaguo Tang,Zhuhui Qiao
Soft metal as the second phase to enhance the mechanical and tribological properties of Si 3 N 4 ceramics was a focus of current research. Limited by the doping method and the low melting point of the metal, there were often phenomena such as nonuniform distribution and melting overflow of the second phase, which seriously deteriorated the properties of Si 3 N 4 . In this study, Cu-containing Si 3 N 4 was prepared by in-situ method using copper citrate as the second phase additive. The highly dispersed second phase helped Si 3 N 4 achieve significant improvements in fracture toughness and tribological properties. The phase composition, microstructure, hardness, fracture toughness, and tribological properties of Cu-containing Si 3 N 4 were investigated. XRD results indicated that the reinforcement phase was in the form of Cu 3 Si. When the Cu 3 Si phase content was 3 wt%, the fracture toughness of Cu-containing Si 3 N 4 could be increased by 27.1 % compared to the Si 3 N 4 . When the Cu 3 Si phase content reached 12 wt%, the wear rate at room temperature was reduced by 59 % compared to the substrate. The toughing mechanism could be summarized as the crack bridging and deflection of the Cu 3 Si phase. The anti-wear mechanism could be concluded as the reduction of micro-cracks in the friction film with the participation of Cu 3 Si phase, thus reducing the loss in the friction process.
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
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
·
2018
·
IF 2.606
Te Qi,Zhihao Zhao,Yongqiang Sun,Hangyuan Zhao,Xiaolei Li,Huiming Ji
Porous Si 3 N 4 ceramics with a unique interlocking microstructure have been fabricated by pressureless liquid-phase sintering with YbF 3 and CaF 2 sintering additives at a relatively low temperature (1550 °C). Phase transition and mass diffusion in the low-temperature sintering process are facilitated by YbF 3 and CaF 2 producing plenty of liquid phase owing to their extremely low melting points. As the content of YbF 3 increases from 8.0 wt% to 9.5 wt% and the CaF 2 decreases from 2.0 wt% to 0.5 wt%, the conversion rate of the phase transition from α-Si 3 N 4 to β-Si 3 N 4 increases from 71.1% to 81.2% and the largest average aspect ratio of the β-Si 3 N 4 grains reaches 10.05. At the same time, the porosity declines from 40.4% to 34.9% and the flexural strength increases from 168.5 MPa to 232.1 MPa.
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
·
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.
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
Qingxuan Zhou,Yang Wang,Zhuoqun Han,Jia Liu,Jie Zhao,Wei Chu,Zhicheng Zhao,Jian Li,Zhiqiang Cheng,Ling Li,Futian Liu
Due to the low powder content characteristic of digital light processing in the preparation of ceramic green bodies, significant challenges arise in obtaining high-density, high-performance Si 3 N 4 ceramic. Sintering aids exert a critical influence on the densification and properties of Si 3 N 4 ceramics. To further improve the performance of 3D-printed Si 3 N 4 ceramics, Si 3 N 4 ceramics were fabricated using DLP technology combined with gas pressure sintering employing different ratios of La 2 O 3 -MgO as sintering aids. The ceramic slurries, microstructures, and ceramic performance were studied systematically. The results showed that increasing the proportion of· La 2 O 3 powder enhanced the rheological and curing properties of Si 3 N 4 ceramic slurries. Varying the La 2 O 3 -MgO ratio affected the composition of the liquid phase, leading to differences in the densification and grain growth of Si 3 N 4 ceramics. The average grain size increased with higher ratios of La 2 O 3 -MgO, and reached a maximum value of 0.91 μm with a ratio of 9:1. With the increase of the La 2 O 3 -MgO ratio, the bulk density and shrinkage rate of the ceramics initially increased and then declined. In addition, the flexural strength and fracture toughness of the ceramics peaked at a ratio of 3:7 for La 2 O 3 -MgO, measuring 577 ± 16.28 MPa and 5.84 ± 0.17 MPa m 1/2 , respectively. These results demonstrate that high-performance Si 3 N 4 ceramics can be effectively prepared using DLP technology by adapting the ratio of sintering additives.
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
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2018
·Vol. 101
·期 11
·4870-4875
·
IF 2.956
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
Based on the previous work on Si 3 N 4 –ZrB 2 [Wu et al. J Eur Ceram Soc ;2017,37:4217], the influence of ZrB 2 addition on the phase and microstructure evolution of Si 3 N 4 –ZrB 2 composites was emphatically investigated, and the mechanical properties were compared with pure Si 3 N 4 ceramics. It was revealed that the ratio of β- to (α+β)-Si 3 N 4 significantly increased from 14.3% in pure Si 3 N 4 ceramics to 39.8% in Si 3 N 4 with 15 vol% ZrB 2 addition, indicating that the introduction of ZrB 2 promoted α- to β-Si 3 N 4 phase transformation. As a consequence, the microstructure of the composite showed the bimodal distribution, containing both elongated and equiaxed Si 3 N 4 grains. For the pure Si 3 N 4 , Vickers hardness, fracture toughness and flexural strength was 22.8 GPa, 7.6 MPa m 1/2 , and 334.5 MPa, respectively. In contrast, the composite of Si 3 N 4 –30 vol% ZrB 2 simultaneously possessed an excellent combination of mechanical properties: 19.5 GPa in hardness, 9.8 MPa m 1/2 in toughness and 702.0 MPa in strength. Present study suggested that Si 3 N 4 -based ceramics with high hardness, high toughness, and high strength could be obtained by the combination of appropriate ZrB 2 content and low hot-pressing temperature.
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
Coatings
·
2023
·Vol. 13
·期 2
·475
·
IF 3.4
Shuai Guo,Fusheng Zhu,Zhimeng Xiu,Mu Zhang,Xudong Sun
In this study, a type of micro-nano Si3N4matrix ceramic cutting tool material was successfully prepared by controlling the addition amount of TiC0.7N0.3and the hot-pressing sintering temperature. The effects of different volume fractions of TiC0.7N0.3on the microstructure, mechanical properties, particle size distribution, and relative density of Si3N4ceramic tools at the same temperature were investigated. The results show that the addition of TiC0.7N0.3makes the β-Si3N4grains with different diameters and aspect ratios interlaced and tightly bonded, thus achieving the strengthening and toughening effects. In addition, the effects of different hot-press sintering temperatures on the properties of Si3N4ceramic tool materials were studied. It was concluded that the density of the material increased with the increase of the hot-pressing temperature. The relative density, flexural strength, and fracture toughness of the samples with 1 vol% TiC0.7N0.3added at 1750 °C and 30 MPa pressure reached 99.22%, 993 MPa, and 9.81 MPa·m1/2, respectively.Keywords:Si3N4;ceramic cutting tool;hot-pressing sintering;TiC0.7N0.3;self-toughening
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
International Journal of Applied Ceramic Technology
·
2024
·
IF 1.8
Zhuoqun Han,Jia Liu,Weiwei Wang,Qingxuan Zhou,Zhicheng Zhao,Yongning Han,Yingying Wang,Yang Wang,Futian Liu,Ling Li
Si 3 N 4 ceramics with high mechanical properties and thermal conductivity, exhibiting fine and bimodal microstructure, were prepared by adjusting the Er 2 O 3 /MgO ratio and hot-pressing sintering at 1800°C for 4 h. The microstructure, grain distribution, lattice oxygen content, mechanical properties, and crack propagation process of the sintered bulk samples were systematically investigated. It was found that a low Er 2 O 3 /MgO ratio contributed to the densification of Si 3 N 4 ceramics, whereas a high Er 2 O 3 /MgO ratio favored the grain growth of Si 3 N 4 ceramics. In this research, the grain size distribution and average diameters as well as their impact on mechanical properties were examined. When the ratio of Er 2 O 3 /MgO was 3:1, Si 3 N 4 had a larger average diameter and higher thermal conductivity, but the mechanical properties were somewhat reduced. When the ratio of Er 2 O 3 /MgO was 2:2, the sample displayed enhanced mechanical performance, which can be explained by the formation of a bimodal structure. The research indicates that it is feasible to control the microstructure and optimize the mechanical properties of Si 3 N 4 ceramics by tailoring the sintering additives.
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）