Crystals
·
2020
·Vol. 10
·期 9
·733
·
IF 2.404
Qixiang Wang,Hong Fang,Di Wang,Jie Wang,Nana Zhang,Bin He,Weiming Lü
The fabrication and transfer of freestanding single-crystal ferroelectric membranes deserve intensive investigations as to their potential applications in flexible wearable devices, such as flexible data storage devices and varied sensors in E-skin configurations. In this report, we have shown a comprehensive study approach to the acquisition of a large-area freestanding single-crystal ferroelectric BaTiO3by the Sr3Al2O6scarification layer method. By controlling the thickness of the BaTiO3and Sr3Al2O6, the exposed area of the Sr3Al2O6interlayer, and the utilization of an additional electrode La2/3Sr1/3MnO3layer, the crack density on the freestanding BaTiO3can be dramatically decreased from 24.53% to almost none; then, a more than 700 × 530 μm2area high-quality freestanding BaTiO3membrane can be achieved. Our results offer a clear and repeatable technology routine for the acquisition of a flexible large-area ferroelectric membrane, which should be instructive to other transition metal oxides as well. Our study can confidently boost flexible device fabrication based on single-crystal transition metal oxides.Keywords:crack density;ferroelectrics;freestanding;single crystal
研究领域:
材料科学
·
柔性电子学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Yehong Cheng,Yang Lyu,Shanbao Zhou,Wenbo Han
Although axially aligned fibrous monolithic ceramics have superior mechanical properties in ceramic fiber axial direction, the obvious anisotropy in physical and chemical properties of fibrous monolithic ceramics predetermine the significant on-axis and off-axis discrepancy. The existing ZrB 2 -based fibrous monolithic ceramics were all arranged by axially aligned ceramic fibers. Non-axially aligned ZrB 2 -SiC/ZrB 2 -SiC-graphene short fibrous monolithic ceramics with isotropic in-plane properties were fabricated by hot pressing of disorderly-arranged short ZrB 2 -SiC/ZrB 2 -SiC-graphene fibers to overcome in-plane anisotropy of the ZrB 2 -based fibrous monolithic ceramics. ZrB 2 -SiC/ZrB 2 -SiC-graphene short fibrous monolithic ceramics have remarkable increase in fracture toughness, critical crack size and work of fracture compared with ZrB 2 -SiC ceramics. The toughening mechanism of ZrB 2 -SiC/ZrB 2 -SiC-graphene short fibrous monolithic ceramics include macroscopic toughening of crack deflection, crack branching, interface friction and ZrB 2 -SiC cell extraction, and microscopic toughening of graphene bridging and pull-out.
研究领域:
材料科学
·
陶瓷
·
复合材料
·
力学性能
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
Yina Du,Ji-Xuan Liu,Yifeng Gu,Xin-Gang Wang,Fangfang Xu,Guo-Jun Zhang
Textured and untextured M n+1 AX n compounds, Ti 2 AlC and Ti 3 AlC 2 , namely MAX phases have been synthesized and examined with respect to their corrosion resistance in static supercritical water at 500 °C. The textured ceramics were obtained by hot forging process at high temperatures. Both X-ray diffraction and SEM analysis revealed well alignment of c -plane of MAX phases parallel to the hot-forging surface. Better corrosion resistance on the surface perpendicular to the hot-forged direction was verified by SEM. On the other hand, the side surfaces of the samples showed thick oxidation layers and abundant cracks. The (00 l ) faces consist of strongly bonded Ti 3 C 2 and Ti 2 C layers in Ti 3 AlC 2 and Ti 2 AlC, respectively, hence exhibit higher resistance to water corrosion. On the contrary, the side surfaces where most of weakly bonded interlayers of these hexagonal phases were exposed tend to be easily corroded especially through Al-layers. The corrosion process involved a phase transition of oxidized product, i.e. TiO 2 from anatase to rutile phase, which gave rise to the formation of cracks due to accompanied volume changes.
研究领域:
材料科学
·
腐蚀工程
✓ 已验证
产品关联
DOI
高影响因子
GIANT
·
2023
·
IF 7
Wenlei Zhang,Yang Gao,Yifan Zhou,Hou Wu,Zhigang Suo,Tongqing Lu
Adhesives are commonly assessed by two properties: strength and toughness. Here we study how strength and toughness are affected by adhesive thickness. We sandwich gelatin adhesives of various thicknesses between glass substrates. The transparency of the adhesives and substrates enables us to observe crack nucleation and growth. We measure strength by lap shear of samples without precrack, and measure toughness by lap shear of samples with precrack. Our data show a characteristic adhesive thickness, about 0.5 mm. For adhesives below the characteristic thickness, strength is independent of thickness, but toughness increases with thickness. For adhesives above the characteristic thickness, strength decreases as thickness increases, but toughness is a constant. Strength scatters narrowly for samples of a thin adhesive, but broadly for samples of a thick adhesive. By contrast, toughness scatters narrowly for samples of all thicknesses. This work shows the importance of assessing adhesives of various thicknesses.
研究领域:
生物力学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
IEEE Transactions on Components Packaging and Manufacturing Technology
·
2024
·
IF 2.3
Yi Zhong,Zhongliang Liu,Binbin Jiang,Dongxiao Yang,Weidong Zhong,Penghui Wu,Tengteng He
Fine-pitch flip-chip Au bumps play a critical role in interconnecting and packaging advanced optoelectronics, historically known for their good corrosion resistance and high reliability. However, this study reveals the susceptibility of Au bumps to corrosion and cracking during 85°C/85%RH high temperature and humidity (THT) reliability testing. Cracks were observed at the under-bump metallization (UBM) interfaces, originating at the bump undercut and propagating towards the bump center. This leads to a dramatic 26.7% reduction in mechanical shear strength, significantly compromising the reliability. The failure mechanism of Au bump was analyzed through the combination of characterization and simulation, which identifies a stress-induced and halogen-enhanced galvanic cell corrosion at the UBM interfaces as the root cause. Furthermore, a protective surface coating strategy involving self-assembled monolayer notably improves bump corrosion resistance, as demonstrated by the absence of strength degradation and interfacial delamination after 500-hour accelerated THT test. These insights are pivotal for advancing reliable, high-performance optoelectronic packaging.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2020
·
IF 4.032
Zhang Xuzhen,Wen Xin,Zhou Chenmeng,Huang Wenjian,Li Yong
Polylactide (PLA) is a representative material in biodegradable polymers, but its application is limited due to the brittleness and poor toughness. In order to investigate the basic brittleness mechanism of PLA, the morphology and formation of spherulite defects in PLA, including ring line cracks with width around 0.3 nm and micropores with diameters of 0.8–1.2 μm, were studied by polarizing microscope and atomic force microscope. The effects of cooling rate, sample thickness, PLA molecular weight, isothermal crystallization temperature and spherulite growth maturity on PLA spherulite defects were discussed. Both ring line cracks and micropores are caused by internal stress caused during PLA melt cooling process, and their morphology would be changed by internal stress distribution with various factors mentioned above. The inhibition of crystal defects will potentially improve the mechanical properties of PLA, thus these results will provide useful references for the toughening modification of PLA.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Ruiji Zhang,Xing Zhang,Chen Xing,Li Hu,Fangwei Guo,Xin Wang,Xiaofeng Zhao
The thermal cycling lifetime of thermal barrier coatings was doubled when deposited by electro-sprayed (ESP) microspheres instead of by commercial hollow spherical powders. It was believed that partial-molten nodules with featured microstructures inherited from the feedstock microspheres were the main contributor for prolonged thermal cycling durability due to improved fracture toughness and strain tolerance. The maximum lifetime was observed on samples with 20−30 vol.% of partial-molten microspheres. The hierarchy pores may both slow down the crack propagation by triggering multi-deflecting and promote cracking by reducing the tendency of interfacial deflection, the net effect depends on situation. The ESP coatings exhibited bimodal Weibull moduli upon indentation, which was regarded as originated from the hierarchy porous structure. Finally, the criterion was verified by micro-indentation and residual stain-stress evaluation by Raman spectroscopy .
研究领域:
材料科学
·
工程学
✓ 已验证
产品关联
DOI
高影响因子
LIQUID CRYSTALS
·
2023
·
IF 2.2
Yongxing Guo,Jinghua Zhao,Yi Li,Wei Liu,Yonggang Yang
Polymer-stabilised cholesteric liquid crystal (PSCLC) films attracted much attention in decoration and anti-counterfeiting. Herein, the PSCLC films were prepared using the mixtures of epoxy monomers through cationic photopolymerisation. The structural colour was tunable by changing the concentration of chiral dopant in the reaction mixture and polymerisation temperature. Due to polymerisation shrinkage, microcracks were formed at the surfaces of the PSCLC films, which originated from the oily streak defects of the CLC mixtures. Colourful patterns were prepared by controlling the polymerisation temperature. In addition, since light can leak out through the microcracks, the tetraphenylethylene-doped patterns can be applied in anti-counterfeiting.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Tingting Lian,Shengchang Zhang,Qibin Xu,Kaixiang Wang,Bo Li,Xiangpu Qin,Mengjin Jiang,Pengqing Liu
The sustainability of epoxy thermosets (EPs) and EP-based composites is always limited by the evolution of internal microcracks and flammability. Herein, inspired by the drug release-delivery system for disease treatment, these symptoms of EP are solved efficiently by a multifunctional Diels–Alder (DA) release-delivery system. First, this novel system is fabricated by the cyclization reaction between the furan diene-containing phosphorus derivative and the maleimide dienophile. The resultant DA system is linked to the epoxy resin by the grafting reaction, thus ensuring its uniform dispersion. Being faced with the formation of inner microcracks, the maleimide dienophiles were released from the DA adducts under the mediated action of temperature and then were delivered to the targeted microcracks under the chemical potential difference derived from the variation of free volume. Then, the released maleimide molecules re-connect with the furan groups that existed near the microcracks to complete the repairing of the EP matrix. The skeletal structure of the EP was well preserved throughout the restoration process. Satisfactory flexural strength (105.5 MPa) and excellent crack-healing efficiency (104.5%) can be obtained for the modified EP. After three constant strain cycles, the stress retention rate can be readily maintained (more than 75%). In addition, due to the phosphorus–nitrogen synergistic flame-retardant effect from the DA system, not only the limited oxygen index of the DA-modified EP matrix can be improved to 27.5% but the lower peak release rate and lower total heat release are also observed compared with the unmodified EP.
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
Extreme Mechanics Letters
·
2021
·
IF 4.567
Qi Li,Ping Zhang,Canhui Yang,Huiling Duan,Wei Hong
On-demand adhere to and detach from soft and wet surfaces are crucial for hydrogels for applications in tissue engineering , soft machines, and soft robotics. Whereas strong adhesion has been achieved between hydrogels, on-demand switching from strong adhesion to weak adhesion for benign detachment is still under explorations. Herein, we report an approach for switchable adhesion between hydrogels by invoking a mechanical process, wrinkling. The approach is demonstrated by bonding two hydrogel adherends with a wrinkled hydrogel adhesive , with the formation and characterizations of wrinkles tailored by regulating the prestretch of adherend and optimizing the ingredients of adhesive synergistically. On one hand, the formation of wrinkles enhances adhesion by creating a tortuous path for crack propagation and an extended energy dissipation zone. The resulting adhesion is robust to elicit bulk dissipation within the adherend and transform the once adhesive failure to cohesive failure . On the other hand, the suppression of wrinkles deactivates the adhesion enhancement mechanism to facilitate effortless debonding. As a proof-of-concept, a hydrogel patch that can strongly adhere to a damaged hydrogel device for repair and gently detach after repairing, based on the switchable hydrogel adhesion, is demonstrated. The proposed method expands the design space for hydrogel adhesion.
研究领域:
生物医学工程
·
材料科学
·
组织工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2022
·
IF 6.364
Anzhe Wang,Shuai Wang,Peng Zhou,Zhen Zhang,Yajie Dai,Dongyang Zhang
The fatigue behavior of a ZrB 2 -based ceramic containing SiC and graphite was compared to a ZrB 2 -SiC reference material based on bending testing, quantitative calculations as well as crack growth and fracture characterization. The addition of graphite flake makes ZrB 2 -SiC-Graphite ceramics exhibit fatigue failure behavior at very high stress level (93% of the characteristic strength , σ 0 ), owing to the increased K Ic promoted by crack deflection, bridging, bifurcation and pull-out of graphite, while the fatigue behavior of ZrB 2 -SiC appears when the maximum stress is below ~86% σ 0 . However, both the slow crack growth exponents of the graphite containing ceramic, n and nc values, which reflect the fatigue resistance in static and cyclic fatigue conditions, respectively, are only 1/4 as compared to the reference graphite-free ceramic. This may be due to the weak boride/graphite interfaces, which lead to the decrease of the initial critical stress intensity factor ( K c-initial ) value from 2.6 to 2.0 MPa m 1/2 .
研究领域:
材料科学
·
工程力学
✓ 已验证
产品关联
DOI
高影响因子
Additive Manufacturing
·
2022
·
IF 11.632
Shufeng Xiong,Jian Liu,Jiwei Cao,Ziyong Li,Muhammad Idrees,Xiao Lin,Zhongyu Long,Zhiyuan Liu,Pei Wang,Changyong Liu,Zhangwei Chen
Previous research often failed to prepared polymer-derived SiOC ceramic components with dense and thick monoliths/skeletons based on additive manufacturing processes, due to the porosities and cracks generated during the pyrolysis process . Herein, we report a simple solution which combines the introduction of phenolic resin (PR) as an additive and the use of controlled strategy of pyrolysis, for the vat photopolymerization additively manufactured SiOC ceramics. As a result, crack-free dense monolith and lattice skeleton structural polymer-derived SiOC ceramics are successfully prepared despite the low ceramic yield of 19.3 wt% and large linear shrinkage of 50% generated after pyrolysis. The prepared dense monoliths possess a thickness of over 5 mm and the lattices show attainable maximum dense skeletons thickness of ~2 mm. The maximum dense thickness of the samples after pyrolysis is over 7 times that of other samples prepared based on additive manufacturing reported in the literature. As an indicator of dimensional retention, the specific dense thickness to ceramic yield ratio (T/Y) is deduced, resulting maximum values of 101.9 µm/(wt%) for lattice skeletons and 254.7 µm/(wt%) for monoliths. The former is even larger than that for dense monolith SiOC structures prepared by other conventional gel casting and isostatic pressing techniques with much higher ceramic yields of > 80 wt%, and is about 6.1 times the largest T/Y ratio (=16.7 µm/(wt%)) achievable in the AM-based works reported in the literature. This shows predominance of the current work over other types of polymer-derived ceramic structures prepared by additive manufacturing and even conventional methods. The lattice structures’ apparent density and specific strength reached 0.55 g/cm 3 and 6.6 × 10 4 N∙m/kg, respectively. The mechanical performance surpasses other structural polymer-derived ceramic structures with similar apparent density reported in the literature. Through the advanced characterization and analysis of material phase and morphology evolution during the pyrolysis process, the mechanism of defect-free densification is revealed. That is, the introduction of PR enables a highly smooth gas-releasing process due to the generation of ordered gas-releasing channels in the sample bodies during the pyrolysis process. As a result, the generation of cracks and defects was successfully prevented. Moreover, due to the high carbon residue of the PR, the samples containing 15 wt% PR in the preceramic state still possessed amorphous SiOC ceramics after pyrolysis at 1400 ℃, while 0 wt% PR samples showed SiC crystallization. Compared with similar materials reported, the ceramics prepared in this study exhibit enhanced structural and mechanical performance. The strategy investigated in the study can be a viable route for the additive manufacturing of high-performance crack-free and thick monolith and lattice skeleton SiOC ceramic structures based on vat photopolymerization.
研究领域:
材料科学
·
制造工程
✓ 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）