scholarly journals Механические свойства композитного покрытия SiC на графите, полученного методом замещения атомов

2021 ◽  
Vol 47 (20) ◽  
pp. 7
Author(s):  
А.С. Гращенко ◽  
С.А. Кукушкин ◽  
А.В. Осипов ◽  
А.В. Редьков
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Silicon Carbide ◽  
Mechanical Characteristics ◽  
Composite Coatings ◽  
Continuous Film ◽  
Silicon Melt ◽  
First Time ◽  
Initial Graphite ◽  
Scanning Electron

The mechanical properties of composite coatings made of silicon carbide on graphite are studied for the first time. For the deposition of coatings, a new method of annealing the initial graphite was used, which was in contact with a silicon melt in an atmosphere of carbon monoxide.The samples were studied by nanoindentation and scanning electron microscopy. It is shown that the formed coating consists of a continuous film of monocrystalline silicon carbide lying on the surface, dendrites and crystalline druses, with roots going deep into the sample through a system of pores. It is shown that the coating significantly increases the mechanical characteristics of the graphite surface, including the microhardness.

STUDY OF MECHANICAL PROPERTIES AND FRACTURE MODE OF ALUMINA-SILICON CARBIDE NANOCOMPOSITES

2012 ◽  
Vol 05 ◽  
pp. 551-558 ◽  
Author(s):  
A. RAHIMNEZHAD YAZDI ◽  
H.R. BAHARVANDI ◽  
H. ABDIZADEH ◽  
N. EHSANI
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Flexural Strength ◽  
Fracture Mode ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sic Particles ◽  
Scanning Electron

In this study Al 2 O 3- SiC nanocomposites have been fabricated by mixing of alumina and silicon carbide nano powders, followed by hot pressing at 1700°C. The mechanical properties and fracture mode of Al 2 O 3- SiC nanocomposites containing different volume fractions (5, 10 and 15%) of nano scale SiC particles were investigated and compared with those of alumina. Al 2 O 3- SiC powders were prepared by planetary milling in isopropanol. Fracture mode of specimens was investigated by means of scanning electron microscopy. Nanocomposites were tougher than alumina when they were hot pressed at the same temperature, and the values of nanocomposite's flexural strength and hardness were higher than those of alumina. Flexural strength, hardness and fracture toughness of the nanocomposites increase by increasing the volume percent of SiC up to 10% and then decrease slightly. The Scanning electron microscopy observations showed that fracture mode changes from intergranular for alumina to transgranular for nanocomposites. Finally X-ray diffraction analysis couldn't detect any chemical reactions between Al 2 O 3 and SiC particles.

scholarly journals Comparative Study on Micromechanical Properties of ZnO:Ga and ZnO:In Luminiscent Ceramics

2021 ◽  
Vol 58 (1) ◽  
pp. 23-32
Author(s):  
F. Muktepavela ◽  
A. Zolotarjovs ◽  
R. Zabels ◽  
K. Kundzins ◽  
E. Gorokhova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Modulus Of Elasticity ◽  
Mechanical Characteristics ◽  
X Ray ◽  
Micromechanical Properties ◽  
Doped Zno ◽  
Hardness Values ◽  
Zno Ceramics ◽  
Scanning Electron

Abstract Indium (0.038 at.%) and gallium (0.042 at.%) doped ZnO ceramics were prepared by hot pressing. Ceramics were investigated to determine their structural and mechanical characteristics for the prospective use in scintillators. Based on results of nanoindentation, atom force and scanning electron microscopy as well as energy dispersive X-ray spectra measurements, locations of gallium within grain, indium at grain boundaries (GBs) and their different effect on the mechanical properties of ZnO ceramics were detected. Doping of gallium led to the increased modulus of elasticity in grain, decreased hardness near GBs, stabilization of micropores and brittle intercrystalline fracture mode. ZnO:In ceramic has modulus of elasticity and hardness values close to ZnO characteristics, the increased fracture toughness and some plasticity near GBs. Differences in the micromechanical properties of the ceramics correlate with the location of dopants. Results demonstrate that the ZnO:In ceramic has a greater stress relaxation potential than the ZnO:Ga.

scholarly journals INVESTIGATION OF PRESSING DIAGRAMS DURING MOLDING A MIXTURE OF COPPER POWDERS AND SILICON CARBIDE

2020 ◽  
pp. 672-680
Author(s):  
Николай Александрович Панькин ◽  
Александр Федорович Сигачев ◽  
Владимир Петрович Мишкин
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Silicon Carbide ◽  
Inelastic Deformation ◽  
Structural Elements ◽  
Cold Forming ◽  
Copper Powders ◽  
Hydrostatic Weighing ◽  
Closed Mold ◽  
Scanning Electron

Проведено исследование смеси порошков меди и карбида кремния после одностороннего холодного формования в закрытой пресс-форме методами: растровой электронной микроскопии, гидростатического взвешивания и анализа диаграмм прессования. Выявлены основные этапы формования, их границы и характерные процессы, происходящие на каждом из них. Установлено, что на диаграмме формования можно выделить не менее трёх областей. Показано, что их границы (по давлению) определяются механическими свойствами материалов используемых порошков и процессами перераспределения / укладки структурных элементов и их упругой/неупругой деформации. A study of a mixture of copper and silicon carbide powders after one-sided cold forming in a closed mold was carried out by methods: scanning electron microscopy, hydrostatic weighing and analysis of pressing diagrams. The main stages of molding, their boundaries and characteristic processes occurring at each of them are identified. It was found that at least three areas can be distinguished on the molding diagram. It is shown that their boundaries (in terms of pressure) are determined by the mechanical properties of the materials of the powders used and the processes of redistribution / packing of structural elements and their elastic / inelastic deformation.

Mechanical Properties and Morphological Correlates of Fragile Skin in Gekkonid Lizards

1989 ◽  
Vol 145 (1) ◽  
pp. 79-102 ◽  
Author(s):  
AARON M. BAUER ◽  
ANTHONY P. RUSSELL ◽  
ROBERT E. SHADWICK
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Body Wall ◽  
Mechanical Interaction ◽  
Loose Connective Tissue ◽  
Gekko Gecko ◽  
First Time ◽  
Typical Vertebrate ◽  
Skin Samples ◽  
Scanning Electron

The mechanical properties of gekkonid lizard skin are investigated for the first time. Although the skin of certain geckos, such as Gekko gecko, behaves in ‘typical’ vertebrate fashion, that of others, such as Ailuronyx seychellensis, exhibits unusual properties associated with identifiable morphological specializations. Light and scanning electron microscopy reveal that Ailuronyx dermis is functionally bilayered; the stratum compactum is divided into inner and outer layers by intervening loose connective tissue. The inner layer is strong and tough and does not differ significantly in its properties from that of Gekko gecko whole skin. The much thicker outer layer, however, is only 1/20 as strong and 1/50 as tough as the inner layer, and exhibits preformed zones of weakness. In nature, Ailuronyx parts with considerable portions of the outer components of the skin as an antipredator escape mechanism. Skin samples from 17 additional gecko species varied considerably in their strength, stiffness and toughness. None of the forms with tough skin employs regional integumentary loss as a predator escape strategy. Weak skin alone is not sufficient to permit regional integumentary loss, as the capability to lose the skin involves not only inherent properties of the tissue, but also features of the mechanical interaction of skin layers with one another and with the underlying body wall.

Manufacture of a Homogenous Nano-Diamond/Poly (Lactic Acid) Bio-Engineered Composite

2008 ◽  
Vol 47-50 ◽  
pp. 1221-1224 ◽  
Author(s):  
Yong Qing Zhao ◽  
Kin Tak Lau ◽  
Hu Lin Li
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Lactic Acid ◽  
Poly Lactic Acid ◽  
Elongation At Break ◽  
Melting Compound ◽  
Transmission Electron ◽  
Bridge Structures ◽  
First Time ◽  
Scanning Electron

A novel nanocomposite based on nanodiamond (ND) powder and Poly (lactic acid) (PLA) for potential bio-engineered applications was fabricated for the first time by using melting compound methods. Its structure and mechanical properties were investigated by using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and tensile property test. The results showed that as compared with pure PLA, ND/PLA nanocomposites possessed higher modulus, higher strength and comparable elongation at break, in other words, the mechanical properties of PLA were significantly improved by incorporating ND powder into it. This is presumably due to homogeneous dispersion of ND cluster, good interfacial bonding and unique ND bridge structures in the ND/PLA nanocomposites.

scholarly journals Morphology and Characterisation of Novolac–LDPE-Based Mixtures as Matrix for Injection Moulded Green Bodies for Bio-Based SiC Ceramics

Ceramics ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 536-550
Author(s):  
Mihalic ◽  
Soares de Sousa ◽  
Burzic ◽  
Hinterreiter ◽  
Stifter ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Mechanical Testing ◽  
Strong Influence ◽  
Phase Distribution ◽  
Process Chain ◽  
Sic Ceramics ◽  
Scanning Electron

This work focuses on the influence of the composition of novolac–LDPE-based mixtures, which serve as a matrix for the green bodies for bio-based silicon carbide (C/Si/SiC) ceramics, on the morphology and the mechanical properties of the green bodies and the ceramics produced thereof. The green bodies were obtained through compounding and injection moulding, and were characterised by scanning electron microscopy (SEM) and mechanical testing. Selected formulations were reinforced with natural fibres, pyrolysed to yield porous carbon templates, and converted into C/Si/SiC ceramics via liquid silicon infiltration. The carbon and ceramic specimens were characterised by light optical microscopy (LOM) and mechanical testing. Without further additives, very coarse morphologies of the novolac–LDPE-based mixtures were obtained, but the miscibility could be improved by the addition of a coupling agent and a lubricant. The pore structure of the carbon specimens was dependent on the phase distribution in the green bodies, and in turn determined the morphology of the C/Si/SiC ceramics. In all steps of the process chain, the morphology had a very strong influence on the mechanical properties. From green bodies with a homogeneous phase distribution, ceramic specimens with a SiC content of up to 75 vol% could be obtained.

Structure and Properties Study of Porous Silicon Carbide Composite Based on SLA

2011 ◽  
Vol 194-196 ◽  
pp. 1590-1593
Author(s):  
Jie Jin ◽  
Maolin Ni ◽  
Shen Hao Wang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Corrosion Resistance ◽  
Porous Silicon ◽  
Structure And Properties ◽  
Porous Silicon Carbide ◽  
Carbide Composite ◽  
Scanning Electron

In the article, porous silicon carbide composite is prepared based on stereo lithography apparatus (SLA). The microstructure of porous silicon carbide composite is characterized by mean of scanning electron microscopy (SEM). The properties of porous silicon carbide composite are studied, such as surface HV and corrosion resistance, and the influence of the pore agent content to mechanical properties.

Electron Microscopic Observation of the Longitudinal Organization of Poly (p-Phenylene Terephthalamide) Fibers

1982 ◽  
Vol 40 ◽  
pp. 680-681
Author(s):  
Li Li-Sheng ◽  
L.F. Allard ◽  
W.C. Bigelow
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Microscopic Observation ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Aromatic Polyamides ◽  
Radial Arrangement ◽  
Scanning Electron ◽  
Better Than

The aromatic polyamides form a class of fibers having mechanical properties which are much better than those of aliphatic polyamides. Currently, the accepted morphology of these fibers as proposed by M.G. Dobb, et al. is a radial arrangement of pleated sheets, with the plane of the pleats parallel to the axis of the fiber. We have recently obtained evidence which supports a different morphology of this type of fiber, using ultramicrotomy and ion-thinning techniques to prepare specimens for transmission and scanning electron microscopy.

SCANNING ELECTRON MICROSCOPE: POSSIBILITIES FOR STUDYING KIDNEY DISEASES

2020 ◽  
pp. 176-182
Author(s):  
Mamaeva S.N. ◽  
Vinokurov R.R. ◽  
Munkhalova Ya.A. ◽  
Dyakonova D.P. ◽  
Platonova V.A. ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Filtration Rate ◽  
Kidney Diseases ◽  
First Time ◽  
Scanning Electron

Currently, due to the intensive development of high-tech science-intensive medical and research devices, more and more attention is paid to the development of diagnostics of rare and difficult to diagnose diseases. It is known that among numerous nephropathies, hematuria may be the only symptom of kidney and urinary tract diseases, which complicates their diagnosis and treatment. In order to develop new approaches for the diagnosis of nephropathies, the authors have been studying the morphology of red blood cells in the blood and urine of children and adults using a scanning electron microscope for several years. The paper presents the results of studies of children with various kidney diseases, including IgA-nephropathy, and chronic glomerulonephritis. Scanning electron microscopy was used for the first time to detect nanoparticles on the surface of red blood cells, the size of which is comparable to the size of viruses, which became the basis for one of the authors ' assumptions, namely, the possible transport of certain types of viruses by red blood cells. Thus, some kidney diseases could be considered virus-associated. This paper presents for the first time the results of determining the glomerular filtration rate of both kidneys separately in the study of separate kidney function and of the study of urine smears obtained during catheterization of the ureters in patients with hydronephrosis of one of the kidneys by scanning electron microscopy. As in previous studies, nanoparticles were found on the surface of red blood cells, which leads to the conclusion about the possible viral nature of the disease of the considered patient. In addition, smear images obtained using a microscope showed a significant difference in the elements of the right and left kidneys urine, which did not contradict the data on the study of glomerular filtration rate. According to the authors, the capabilities of the scanning electron microscope can be applied in fundamental research of kidney diseases at the cellular and molecular levels, forming new ideas about their origin, as well as on the basis of which new methods of non-invasive diagnostics can be built.

scholarly journals Labellum and gynostemium micromorphology in Polystachya (Orchidaceae)

2020 ◽  
Vol 307 (1) ◽  
Author(s):  
Mytnik Joanna ◽  
Davies L. Kevin ◽  
Narajczyk Magdalena ◽  
Łuszczek Dorota ◽  
Kubiak Joanna ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Sub Saharan Africa ◽  
Capitate Trichomes ◽  
Sub Saharan ◽  
First Time ◽  
Scanning Electron

AbstractPolystachya is a large, pantropical orchid genus of 200 species, most of which occur as epiphytes in sub-saharan Africa. The three-lobed labellum of most Polystachya species possesses a fleshy callus and various types of trichomes and papillae. In this paper, we present the results of micromorphological studies on the labellum of 20 species, representing eight of the 13 sections in the genus, using scanning electron microscopy (SEM). Our results show the scale of infrageneric diversity of trichomes and papillae relative to the sampled sections. They also demonstrate the taxonomic value of labellar micromorphology at the sectional level. The study revealed seven types of papillae and five types of trichomes (uni- and multi-cellular) in Polystachya, some of which, are described here for the first time. Clavate trichomes are the most common and are present in 60% of the species studied. Moniliform trichomes mainly occur in sect. Polystachya and are strongly characteristic of the section. Pseudopollen is formed by fragmentation of moniliform trichomes or the detachment of other trichomes as bicellular units. We provide, for the first time, evidence for the detachment of the terminal cells of capitate trichomes.

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