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991.
The effects, during formation, of current density, charge capacity, and concentration and temperature of H2SO4 electrolyte on the capacity of tubular electrodes in lead/acid batteries have been studied. Electrode capacity was found to be maximum at a H2SO4 concentration of 1.05 sp. gr., a charge amount of 250% theoretical capacity, a current density of 0.44 A dm?2, and an electrolyte temperature of 40 °C. A study of the soaking process for tubular electrodes showed the electrode capacity to be maximum when the acid absorption was about 170 mg of H2SO4 per g of oxide. Finally, the discharge overpotential of tubular electrodes was analyzed by a galvanostatic transient method. 相似文献
992.
Y. Yang B. F. Wang J. Xiong Y. Zeng Z. P. Chen X. Y. Yang 《Metallurgical and Materials Transactions A》2006,37(10):3131-3137
The microstructure and microtexture in adiabatic shear bands (ASBs) on the titanium side in the titanium/mild steel explosive
cladding interface are investigated by means of optical microscopy, scanning electron microscopy/electron backscattered diffraction
(SEM/EBSD), and transmission electron microscopy (TEM). Highly elongated subgrains and fine equiaxed grains with low dislocation
density are observed in the ASBs. Microtextures (25 deg, 75 deg, 0 deg), (70 deg, 45 deg, 0 deg), and (0 deg, 15 deg, 30 deg)
formed within the ASBs suggest the occurrence of the recrystallization. The grain boundaries within ASBs are geometrically
necessary boundaries (GNBs) with high angles. Finite element computations are performed to obtain the effective strain and
temperature distributions within the ASBs under the measured boundary conditions. The rotation dynamic recrystallization (RDR)
mechanism is employed to describe the kinetics of the nanograins’ formation and the recrystallized process within ASBs. During
the deformation time (about 5 to 10 μs), the following processes take place: dislocations accumulate to form elongated cell
structures, cell structures break up to form subgrains, and subgrains rotate and finally form recrystallized grains. The small
grains within ASBs are formed during the deformation and do not undergo significant growth by grain boundary migration after
deformation. 相似文献
993.
994.
Microstructure-composition relationships and Ms temperatures have been determined in high purity nitrided Fe-Cr-Mn alloys, as part of a program to develop improved corrosion-abrasion
resistant steels with unstable austenitic microstructures. Compositions in the range 8 to 12 pct Cr, 0 to 10 pct Mn, and 0
to 0.6 pct N were investigated by a resistivity technique to determine Ms temperatures and by X-ray diffraction and metallography to determine constitution. Hardness measurements were also made.
At the low alloy end of the range, microstructures after annealing and air cooling are fully martensitic while at the high
alloy end they are fully austenitic. At intermediate compositions, mixed martensite-austenite microstructures (with epsilon
present as a minor phase in some cases) and unstable austenitic microstructures are obtained. The austenitic alloys contain
a high density of stacking faults and the unstable austenitic alloys transform to martensite on deformation. At low N contents
(up to at least 0.25 pct N) the Ms-composition relationship is linear and described by: Ms = 555 - 9(Cr - 8) - 40Mn - 450N [1] where Ms is in °C and Cr, Mn, and N are the weight percentages of these elements. At higher N contents, the Ms generally falls more rapidly with increasing nitrogen content. Nitrogen solubility at 1050 °C exceeds about 0.3 pct in all
alloys and increases with increasing Cr and Mn content. In commercial purity steels, unstable austenitic microstructures are
expected to be obtained in compositions around 10 to 14 pct Cr, 8 to 12 pct Mn, and 0.1 to 0.3 pct N when the total level
of these elements is selected to ensure the Ms is below room temperature. 相似文献
995.
996.
997.
998.
The frequency characteristics of a Salisbury screen radar absorber that incorporates a layer exhibiting both resistive and capacitive properties are considered. If the capacitance is fixed, the absorber thickness and hence weight may be reduced but at the expense of bandwidth. If the capacitance is variable then the absorber may be tuned via an external control signal. The practical limitations of both applications are discussed in relation to recent advances in conducting polymer materials 相似文献
999.
The authors present experimental results which indicate that a Dy 3+-doped Ga:La:S glass fibre amplifier may be operated efficiently at 1.3 μm with an optimum device length significantly shorter than a comparable Pr3+-doped glass fibre amplifier. Moreover, the efficiency exceeds that obtained from the Pr3+-doped ZBLAN devices currently available 相似文献
1000.
The cyclic crack growth behaviour was measured by means of d.c. potential drop, a.c. potential drop, ultrasonic and crack-opening displacement (COD) methods. The methods were applied to component tests on straight pipes with an outer diameter of approximately 800 mm and a wall thickness of approximately 50 mm. The pipes were subjected to constant internal pressure (about 15 MPa) and either an alternating (or pulsating) or a quasi-static bending moment using d.c. potential drop, a.c. potential drop, ultrasonic and flaw-opening (COD) methods. The efficiency of the particular methods has been proved by comparison with fractographical analysis of the fracture surfaces. 相似文献