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81.
82.
The effect of the grain size of the filler on the mechanical properties (compressive, bending, and tensile strength and modulus of elasticity) of synthetic graphite is analyzed using data for commercial structural graphites. As the mean particle size of the filler (av) decreases from 3000 to 1 m, the modulus of elasticity increases, on the average, from 10 to 15 GPa, and the compressive, bending, and tensile strength increases by about one order of magnitude. The Griffith equation is used to evaluate the size of defects that initiate fracture (c
c) in different types of graphites. It is shown that the factors determining the critical defect size depend on the particle size of the filler. For av > 150 m, c
c is comparable to av or max. In the range 30 < av < 150 m, c
c is equal to or greater than max. In graphites with av < 30 m, c
c far exceeds max and, presumably, corresponds to the particle size of the molding powder. 相似文献
83.
An attempt was made to reduce the carrier concentration in thin PbTe films on Si substrates by optimizing deposition conditions.
A modified hot-wall method was used for reproducible growth ofp-type films with 5 × 1015 < p(77 K) < 5 × 1017 cm-3 andn-type films with 3 × 1015 < n(77 K) < 5 × 1016 cm-3. The IR irradiation was found to have a significant effect on the temperature variation of film resistance. The activation
energy of the IR-sensitivity centers was determined to be 0.11 ± 0.005 eV at room temperature and 0.18 ± 0.005 eV between
150 and 180 K. 相似文献
84.
A. I. Orlova D. V. Kemenov S. G. Samoilov G. N. Kazantsev V. I. Pet’kov 《Inorganic Materials》2000,36(8):830-834
The thermal expansion of the A
x
Zr2.25-0.25x(PO4)3 phosphates with A = Na(x = 0.5,1.0,2.0,3.0,4.0, 5.0) and K(x = 1.0, 3.0, 5.0), crystallizing in structures of the NaZr2(PO4)3 type (sp. gr.R3c or C2/c), was studied by high-temperature x-ray powder diffraction in the range 20–700‡C. The lattice parametersa and c and thea- andc-axis thermal expansion coefficients (αa and αc) were determined. The thermal expansion of the phosphates was found to be highly anisotropic (αa < 0, αc > 0). The strongest anisotropy was found in NaZr2(PO4)3 (αa = -4.89 x 10-6 K-1, αc = 22.02 x 10-6 K-1), KZr2(PO4)3 (αa =-5.30 x 10-6 K-1, αc = 5.41 x 10-6 K-1), and Na5Zr(PO4)3 (αa = -5.82 x 10-6 K-1, αc
= 20.73 x 10-6 K-1). K5Zr(PO4)3 exhibited the smallest thermal expansion and weak anisotropy (αa = -2.14 x 10-6 K-1, αc = 2.65 x 10-6 K-1). The effects of M(l) and M(2) site occupancies on αa, αc,a, and c were assessed. The relative magnitudes of crystal-chemical and thermal expansion in the Na and K compounds were analyzed. 相似文献
85.
86.
87.
N. A. Azhishchev V. A. Antipin A. A. Borisov V. A. Samoilov 《Journal of Engineering Physics and Thermophysics》1987,52(1):9-12
It was established experimentally that the form and velocity of a rarefaction wave in free charges depends on the particle size. Three regimes of wave propagation were observed — wave, with superposed filtration, and filtration through a stationary charge.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 52, No. 1, pp. 15–19, January, 1987. 相似文献
88.
The influence of an external, pulse-periodic, energy supply source on the aerodynamic characteristics of a hemisphere positioned
downstream is simulated.
Pis’ma Zh. Tekh. Fiz. 23, 1–8 (May 12, 1997) 相似文献
89.