JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Chufei Cheng,Ruixin Hao,Jiadong Hou,Fengnian Zhang,Fuhao Cheng,Ziqian Meng,Bei Ren,Yang Miao,Libiao Xin,Xiaomin Wang
In the thermal protection system of spacecraft, the bolts connecting the ceramic to the internal superalloy need to have low thermal conductivity and high strength . Two dense high entropy fluorite oxides (Zr 1/7 Hf 1/7 Ce 1/7 Y 2/7 La 2/7 )O 2-δ (ZHCYL) and (Zr 1/8 Hf 1/8 Ce 1/8 Y 1/4 La 1/4 Pr 1/8 )O 2-δ (ZHCYLP) were designed and synthesized by using the synergistic effect of plasma-assisted ball milling and spark plasma sintering(SPS). Through the synergistic effect of lattice distortion and oxygen vacancy guided by entropy regulation, ZHCYLP synthesized in this study has lower thermal conductivity(1.13 W·m −1 ·K −1 ), higher high temperature strength(192 MPa at 1000 °C) and high temperature phase stability up to 1600 °C than 8YSZ ceramics. The thermo-mechanical coupling finite element analysis results of high temperature bending test show that the variation trend of the maximum stress value of the sample is consistent with the experimental results. This shows that the mechanical and thermal properties of high entropy oxides can predict the variation trend of the maximum stress value in high temperature bending tests. It opens up a new way for designing and synthesizing high entropy oxide materials with low thermal conductivity and high strength which can be applied in the field of heat protection and load bearing.
研究领域:
材料科学
·
航天工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yingjun Liu,Jianjun Sha,Cheng Su,Jixiang Dai,Yufei Zu
Sintering additive of ZrSi 2 is beneficial to low-temperature densification of ZrB 2 -based ultra-high temperature ceramics (UHTCs), nevertheless, residual ZrSi 2 would severely reduce the high-temperature strength of UHTCs. In the current work, to achieve low-temperature preparation of ZrB 2 -based UHTCs with good high-temperature strength, active carbon (C) was added into ZrB 2 –ZrSi 2 ceramics to convert the sintering additive into refractory phases of SiC/ZrC. C-doped ZrB 2 –ZrSi 2 powders were hot-pressed at different temperatures to investigate the phase composition, microstructure and densification behavior. TG-DSC, XRD and SEM results indicated that ZrSi 2 was almost entirely converted into SiC and ZrC at 1600 °C for 2h, meanwhile, a fully-dense C-doped ZrB 2 –ZrSi 2 ceramic was obtained at such sintering conditions. In addition, the high-temperature (1800 °C) strength of C-doped ZrB 2 –ZrSi 2 ceramic was 390 ± 21 MPa, which was much higher than that of the C-undoped one. The excellent high-temperature mechanical properties could be attributed to the transformation of low-melting-point phases into refractory phases.
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
Shiquan Zhang,Jian Zhang,Suohui Yang,Minxian Shi,Junguo Li,Qiang Shen
Ablation material had been widely used in aerospace attributed to its reliability and strong adaptability but was usually accompanied by low strength at higher temperatures. Here, a high flexural strength of 66.91 MPa after ablation at 1500 °C of carbon fiber/boron phenolic resin (CF/BPR) composite modified by MoSi 2 and mica was reported. With the proportion of MoSi 2 and mica was 9:1, the formed appropriate content of the liquid phase improved the reactivity of MoSi 2 powders and provided a suitable interfacial state between CF and the matrix. The result of the oxygen-acetylene test showed that the mass ablation and the linear ablation reduced to 0.034 g/s and 0.006 mm/s, respectively. Owing to the formed liquid phase wrapping the carbon fiber and ceramic layer on the surface improved the ablation resistance. These high-strength CF/BPR composites have strong potential in new aerospace materials.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
DOI
高影响因子
ACS Applied Polymer Materials
·
2022
·
IF 4.855
Sizhao Zhang,Zhao Wang,Jing Wang,Yunyun Xiao,Zhouyuan Yang,Hui Ji,Guangyu Xu,Shixian Xiong,Zhengquan Li,Feng Ding
High performance polyimide aerogels (PIA) are highly desirable as a part of thermal protection systems for aircraft. However, the large drying shrinkage and insufficient thermal insulation of PIA limit their practical applications in the aerospace field. Herein, the strategy of two-step prepolymerization and polycondensation route was proposed to fabricate PIA with ultralow drying shrinkage, outstanding thermal insulation, hydrophobicity, machinability, compressive strength in cryogenic/high-temperature atmospheres, flame resistance, and fantastic dimensional stability. In more detail, the drying shrinkage rate of PIA series can be lowered to 1.84%, mainly owing to the strengthened skeletons by chemical bond formation and physical entanglement of molecular chains. Excellent thermal insulation is reflected upon keeping an ink drop state as long as 265 s despite placing it on a cold surface with a temperature of −196 °C. PIA-O2B2 are imparted with hydrophobic properties (with water contact angle of 135°) depending on the hydrogen-bonding interaction between polyimide networking chains and 1H,1H,2H,2H-perfluorodecyltriethoxysilane that was introduced. In addition, the exceptional flame retardant is endowed completely, which is attributed to the evidence of the presence of aromatic ring structures in constructing the aerogel. The high-temperature shrinkage rate of PIA series is as low as 4.81% due to the relative small free volume of the molecular chains. Our study would provide a method for designing ultralow drying shrinkage and superb thermal insulation in cryogenic conditions for PIA in aerospace uses.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Andong Hua,Yishi Su,Yunpeng Cai,Di Zhang,Qiubao Ouyang
Aiming at developing new B 4 C/Al neutron absorbing materials with both high thermal neutron absorption performance and high-temperature strength for neutron shielding applications, B 4 C/SiC/2024Al composites were fabricated by powder metallurgy process. TEM results revealed that SiC nanowires were distributed at Al grain boundaries and bonded tightly with Al matrix . Grain boundary sliding and grain rotation were efficiently restricted and prevented dislocation annihilation at GBs. The thermal stability of composite was improved by adding SiC nanowires and achieved a high-temperature strength of 163.4 ± 1.8 MPa at 573 K, which was increased by 92.2 % compared to the composite without addition of SiC nanowires. By analyzing the strengthening mechanism , dislocation strengthening was the dominant factor in the improvement of high-temperature strength. As for neutron absorption application, B 4 C/SiC/2024Al composite exhibited not only good high-temperature strength but also remarkable neutron absorption performance and matched thermal conductivity and coefficient of thermal expansion .
研究领域:
材料科学
·
核工程
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES PART B-ENGINEERING
·
2021
·
IF 9.078
Zhen Lu,Dekai Liu,Chengcheng Shi,Han Xiao,Wei Liu,Shaosong Jiang
NiAl intermetallic compounds have attracted the attention of researchers in the field of high-temperature structural materials, but their poor room-temperature ductility and insufficient high-temperature strength crying out for solutions have hindered their practical application. To solve these problems, a novel 3-dimensional network structure-reinforced NiAl-based composite was designed by hot presing sintering sinter with pre-alloyed powders. The 3-dimensional network structure was composed of discrete nearly spherical HfO 2 and rod-shaped HfRe 2 . The mechanical properties of the composites were closely correlated with the distribution of the 3-dimensional network structure in the matrix, which was controlled by the sintering temperature and holding time. A microstructure with a desirable 3-dimensional network structure distribution and the best comprehensive mechanical properties was produced at 1375 °C/60 min. The microstructural evolution along with the strengthening and toughening mechanisms were discussed in detail. The increase in the high-temperature strength was mainly attributed to the pinning effect of the 3-dimensional network structure on dislocations and the restraining effect on the sliding and rotation between the matrix grains, while the increase in room-temperature ductility was mainly due to the grain refinement and hindering of crack propagation by the 3-dimensional network structure. In this paper, the development of a novel low-density NiAl-based composite with a 3-dimensional network structure improved both the strength and ductility, providing design ideas for the application of NiAl-based materials.
研究领域:
材料科学
·
力学
✓ 已验证
DOI
高影响因子
Science China-Materials
·
2023
·Vol. 66
·期 5
·2061-2070
·
IF 8.1
Liu Jie,Yang Qing-Qing,Zou Ji,Wang Wei-Min,Wang Xin-Gang,Fu Zheng-Yi
In this study, a type of high-entropy boride (HEB) ceramics ((Ti 0.2 Zr 0.2 Nba 0.2 Hfa 0.2 Taa 0.2 )B 2 ) with ∼2vol% oxides and ∼1 vol% porosity was successfully consolidated by spark plasma sintering at 2000°C under a uniaxial load of 50 MPa for 10 min, using self-synthesized high entropy diboride powders from a boro/carbothermal reduction approach. The residual oxides were determined to be m-(Hf,Zr)O 2 , which were incorporated with minor amounts of boron and carbon. Elastic modulus, Vickers hardness and fracture toughness of HEBs at room temperature were 508.5 GPa, 17.7 ± 0.4 GPa and 4.2 ± 0.2 MPa m 1/2 , respectively. The as-obtained ceramics possessed excellent flexural strength, particularly at high temperatures. The four-point flexural strengths of HEBs at room temperature, 1600, and 1800°C are 400.4 ± 47.0, 695.9 ± 55.9, and 751.6 ± 23.2 MPa, respectively. Postmortem analysis was conducted on HEB fractured at 1800°C, in the region near their tensile and fracture surfaces, and microstructure observations show that limited dislocation lines were present adjacent to the crack front and edge of the pore, without noticing any trace for dislocation motions. It is the first report on the high-temperature strength of high-entropy diboride ceramics and the strengthening mechanism at high temperatures was also discussed.
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）