Electrical resistivity of hot-pressed TiC-SiC-C composite materials

1982 ◽  
Vol 21 (11) ◽  
pp. 867-871 ◽  
Author(s):  
S. G. Gorinskii ◽  
A. R. Beketov ◽  
I. L. Shabalin ◽  
M. I. Podkovrykin ◽  
A. F. Kokorin
2011 ◽  
Vol 284-286 ◽  
pp. 1842-1845
Author(s):  
Jue Wang ◽  
Gui Xiang Hou

Polystyrene(PS)/Polystyrene-expanded graphite(EG)(PS/PSEG) composites were prepared by melt blending, using a variety of PSEG. The electrical and mechanical properties of the PS/PSEG were measured. Mechanical property measurements of composites indicated higher impact strength and lower tensile strength with increasing content of PSEG. Exfoliated graphite has seen a significant reduction for composites in electrical resistivity.


2010 ◽  
Vol 163-167 ◽  
pp. 1991-1994 ◽  
Author(s):  
Gui Xiang Hou ◽  
Sheng Yuan Liu ◽  
Xiao Ming Sang

Polystyrene (PS)/Poly(S-co-MA)/expanded graphite(EG)(PS/PSMA/EG) nanocomposites were prepared by melt blending, using a variety of PSMA/EG.. The electrical and mechanical properties of the PS/PSMA/EG were measured. Mechanical property measurements of composites indicated higher impact strength and lower tensile strength with increasing concentration of PSMA/EG. Exfoliated graphite has seen a significant reduction for composites in electrical resistivity.


Author(s):  
R.R. Russell

Transmission electron microscopy of metallic/intermetallic composite materials is most challenging since the microscopist typically has great difficulty preparing specimens with uniform electron thin areas in adjacent phases. The application of ion milling for thinning foils from such materials has been quite effective. Although composite specimens prepared by ion milling have yielded much microstructural information, this technique has some inherent drawbacks such as the possible generation of ion damage near sample surfaces.


Author(s):  
K.P.D. Lagerlof

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.


Author(s):  
W. E. King

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).


Author(s):  
H. Kung ◽  
A.J. Griffin ◽  
Y.C. Lu ◽  
K.E. Sickafus ◽  
T.E. Mitchell ◽  
...  

Materials with compositionally modulated structures have gained much attention recently due to potential improvement in electrical, magnetic and mechanical properties. Specifically, Cu-Nb laminate systems have been extensively studied mainly due to the combination of high strength, and superior thermal and electrical conductivity that can be obtained and optimized for the different applications. The effect of layer thickness on the hardness, residual stress and electrical resistivity has been investigated. In general, increases in hardness and electrical resistivity have been observed with decreasing layer thickness. In addition, reduction in structural scale has caused the formation of a metastable structure which exhibits uniquely different properties. In this study, we report the formation of b.c.c. Cu in highly textured Cu/Nb nanolayers. A series of Cu/Nb nanolayered films, with alternating Cu and Nb layers, were prepared by dc magnetron sputtering onto Si {100} wafers. The nominal total thickness of each layered film was 1 μm. The layer thickness was varied between 1 nm and 500 nm with the volume fraction of the two phases kept constant at 50%. The deposition rates and film densities were determined through a combination of profilometry and ion beam analysis techniques. Cross-sectional transmission electron microscopy (XTEM) was used to examine the structure, phase and grain size distribution of the as-sputtered films. A JEOL 3000F high resolution TEM was used to characterize the microstructure.


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