scholarly journals Influences of Increased Pressure Foaming on the Cellular Structure and Compressive Properties of In Situ Al-4.5%Cu-xTiB2 Composite Foams with Different Particle Fraction

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2612
Author(s):  
Zhengyi Niu ◽  
Zhentao An ◽  
Zhibao Jiang ◽  
Zhuokun Cao ◽  
Yang Yu
Keyword(s):  
Cell Wall ◽  
Energy Absorption ◽  
Cellular Structure ◽  
Cell Structure ◽  
Metallic Foams ◽  
Particle Fraction ◽  
Composite Foams ◽  
Tib2 Particles ◽  
Increased Pressure

Metallic foams have drawn increasing attention in applications ranging from lightweight structures to energy absorption devices. Mechanical properties of metallic foams depend on both their microstructure and cellular structure. In situ Al-4.5%Cu-xTiB2 composites were used as start materials for fabrication of closed-cell foams through liquid route under atmosphere pressure and increased pressure, aiming at simultaneously strengthening the cell wall material and optimizing the cellular structure. Macro-structural features of the foams were determined by micro X-ray computed tomography (µCT); results exhibit that increasing weight ratio of in situ TiB2 particles leads to coarsened cell structure for foams made under atmosphere pressure, due to the increase in critical thickness of cell wall rupture. Significant reduction of cell size and increase in cell circularity were observed for foams fabricated under increased pressure. Quasi static compression test results indicate that yield strength of foam samples increases with increasing particle fraction and refinement of cell structure. Microstructure observation shows that the continuous network at interdendritic regions consists of in situ TiB2 particles and intermetallic compounds are responsible for the reduced ductility of cell wall materials and the reduction in energy absorption efficiency of foams with high particle fraction. The influences of cell structure on the normalized strength and specific energy absorption were also discussed, and it was found that the improvement of yield strength and energy absorption of composite foams attributes to both the reinforcement of in situ TiB2 particles and the refinement of cellular structure.

Elevated temperature compressive properties and energy absorption response of in-situ grown CNT-reinforced Al composite foams

2017 ◽  
Vol 690 ◽  
pp. 294-302 ◽  
Author(s):  
Kunming Yang ◽  
Xudong Yang ◽  
Enzuo Liu ◽  
Chunsheng Shi ◽  
Liying Ma ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Energy Absorption ◽  
Compressive Properties ◽  
Composite Foams ◽  
Al Composite

Compressive Response and Energy Absorption Characteristics of In Situ Grown CNT-Reinforced Al Composite Foams

2017 ◽  
Vol 19 (12) ◽  
pp. 1700431 ◽  
Author(s):  
Xudong Yang ◽  
Kunming Yang ◽  
Jiwei Wang ◽  
Chunsheng Shi ◽  
Chunnian He ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Compressive Response ◽  
Composite Foams ◽  
Al Composite ◽  
Absorption Characteristics

scholarly journals Compressive Behavior of Al-TiB2 Composite Foams Fabricated under Increased Pressure

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5112
Author(s):  
Yang Yu ◽  
Zhuokun Cao ◽  
Jiaqi Wang ◽  
Ganfeng Tu ◽  
Yongliang Mu
Keyword(s):  
Size Distribution ◽  
Cell Size ◽  
Energy Absorption ◽  
Absorption Efficiency ◽  
Compression Tests ◽  
Cell Size Distribution ◽  
Size Refinement ◽  
Composite Foams ◽  
Stress Fluctuation ◽  
Increased Pressure

The application of increased pressure was used as a strategy to investigate the effect of different cell structures on the mechanical properties of Al-TiB2 composite foams. In situ Al-xTiB2 (x = 5, 10 wt.%) composites were foamed under three different pressures (0.1 MPa, 0.24 MPa, 0.4 MPa) through the liquid melt route. The macro-structure of the composite foams was analyzed in terms of cell size distribution measured by X-ray microcomputed tomography (micro-CT). It was found that the mean cell size decreases, and the cell size distribution range narrows with increasing pressure. Uniaxial compression tests revealed that the stress fluctuation (Rsd) of 10TiB2 foams is larger than that of 5TiB2 foams under the same pressure. Moreover, cell size refinement causes the simultaneous deformation of multi-layer cells, which leads to an enhancement in the energy absorption efficiency and specific energy absorption. The comparison of experimental data with theoretical predictions (G&A model) is discussed.

Compressive properties and energy absorption of aluminum composite foams reinforced by in-situ generated MgAl 2 O 4 whiskers

2015 ◽  
Vol 645 ◽  
pp. 1-7 ◽  
Author(s):  
Cheng Guo ◽  
Tianchun Zou ◽  
Chunsheng Shi ◽  
Xudong Yang ◽  
Naiqin Zhao ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Compressive Properties ◽  
Aluminum Composite ◽  
Composite Foams

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Cell structure properties during in situ creep experiments in the H.V.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 574-575
Author(s):  
D. Caillard ◽  
J.L. Martin
Keyword(s):  
Tensile Axis ◽  
Cell Structure ◽  
Image Intensifier ◽  
Foil Thickness ◽  
Average Cell Size ◽  
Average Cell ◽  
Voltage Electron ◽  
Steady Stage ◽  
Stationary Creep

The behaviour of the dislocation substructure during the steady stage regime of creep, as well as its contribution to the creep rate, are poorly known. In particular, the stability of the subboundaries has been questioned recently, on the basis of experimental observations |1||2| and theoretical estimates |1||3|. In situ deformation experiments in the high voltage electron microscope are well adapted to the direct observation of this behaviour. We report here recent results on dislocation and subboundary properties during stationary creep of an aluminium polycristal at 200°C.During a macroscopic creep test at 200°C, a cell substructure is developed with an average cell size of a few microns. Microsamples are cut out of these specimens |4| with the same tensile axis, and then further deformed in the microscope at the same temperature and stain rate. At 1 MeV, one or a few cells can be observed in the foil thickness |5|. Low electron fluxes and an image intensifier were used to reduce radiation damage effects.

scholarly journals Morphological, thermal, and thermomechanical properties of cellulose nanocrystals reinforced polylactide/poly [(butylene succinate)-co-adipate] blend composite foams

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Mpho Phillip Motloung ◽  
Simphiwe Zungu ◽  
Vincent Ojijo ◽  
Jayita Bandyopadhyay ◽  
Suprakas Sinha Ray
Keyword(s):  
Morphological Analysis ◽  
Cell Structure ◽  
Environmentally Friendly ◽  
Processing Technique ◽  
Thermomechanical Properties ◽  
Environmental Concerns ◽  
Butylene Succinate ◽  
Peak Intensity ◽  
Composite Foams ◽  
Reinforcing Agent

Abstract This study examines the influence of cellulose nanocrystal (CN) particles on the morphological, thermal, and thermo-mechanical properties of polylactide (PLA)/poly [(butylene succinate)-co-adipate] (PBSA) blend foams prepared by casting and particulate leaching method using fructose as porogen particles. The morphological analysis showed an interconnected open-cell structure, with porosity above 80%. The crystallinity of the prepared foams was disrupted by the inclusion of CN particles as observed from XRD analyses, which showed a decrease in PLA crystal peak intensity. With regards to neat blend foam, the onset thermal degradation increased with the addition of CN particles, which also increased the thermal stability at 50% weight loss. Furthermore, CN acted as a reinforcing agent in improving the stiffness of the prepared blend foam. Overall, completely environmentally friendly foams were successfully prepared, as a potential material that can replace the current existing foam materials that pose many environmental concerns. However, there is a need to develop an environmentally friendly processing technique.

scholarly journals Astringency in ʻGiomboʼ persimmon and its relationship with the harvest time

Revista CERES ◽  
2016 ◽  
Vol 63 (5) ◽  
pp. 646-652
Author(s):  
Magda Andréia Tessmer ◽  
Beatriz Appezzato-da-Glória ◽  
Ricardo Alfredo Kluge
Keyword(s):  
Cell Wall ◽  
Exposure Time ◽  
Fruit Quality ◽  
Cell Structure ◽  
Parenchyma Cell ◽  
Growing Season ◽  
Ethanol Exposure ◽  
Harvest Time ◽  
Intercellular Spaces ◽  
Parenchyma Cell Wall

ABSTRACT ʻGiomboʼ is one of most cultivated persimmon cultivars in Brazil. It is a late-harvest cultivar and requires treatment for astringency removal. The aim of this study was to evaluate the efficiency of ethanol and the effect of harvest time on reducing astringency, physicochemical and anatomical characteristics of 'Giombo' persimmon. Two experiments were carried out, one in each growing season, with five treatments corresponding to exposure to 1.70 mL kg-1ethanol for 0, 12, 24, 36 and 48 hours. At the end of the growing season (2011) the fruits achieved the astringency index and levels of soluble tannins suitable for consumption in 24 hours, and at the beginning of the growing season (2012) in 36 hours, indicating that the efficiency of the treatment is related to harvest time and ethanol exposure time. Astringency removal with ethanol affects the cell structure with accumulation of substances inside the cells and in intercellular spaces, resulting in the degradation of the parenchyma cell wall. To avoid such damage and maintain fruit quality, it is recommended the combination of low ethanol doses with less ethanol exposure time.

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