This study examines the effect of microstructurally different regions on the hot corrosion of tungsten inert gas weldment
in 2.25Cr-1Mo (T22) boiler tube steel. Various regions of weldment were oxidized in molten salt Na2SO4-60% V2O5 environment at 900 °C. The base metal was found to oxidize at much higher rates than the weld metal and the heat-affected
zone. Oxide scales formed in the three regions were compared by scanning electron microscopy with energy dispersive of X-ray
analysis, X-ray diffraction pattern, and electron probe microanalysis. The research investigates the formation of inner scales
with free Cr over the HAZ. 相似文献
Direct methanol fuel cells have potentially high energy density if the balance of plant and fuel losses can be kept to a minimum. CO2 accumulation in the fuel tank can lower the efficiency and performance of closed-tank methanol fuel cells. This report discusses the implementation of a passive CO2 vent fabricated with poly(1-trimethyl silyl propyne) and 1,6-divinylperfluorohexane. The performance of the membrane as a selective vent for carbon dioxide in the presence of methanol has been studied at various operating conditions. First, the selectivity of the vent membrane improved with temperature. Second, the activation energy for permeation through the polymer membrane corresponded to diffusion controlled transport of CO2 and sorption controlled transport for methanol vapor. The activation energy for CO2 transport through the poly(1-trimethyl silyl propyne) and 1,6-divinylperfluorohexane membrane was less than that for a pure poly(1-trimethyl silyl propyne) membrane. Finally, the polymer had a high selectivity for carbon dioxide compared to both liquid and vapor phase methanol. 相似文献
A high-speed directional comparison relay based on an evaluation of the locally measured deviations of the voltage and the phase-shifted current from their prefault values is described. The operation of the relay depends on the power frequency components of the voltage and phase-shifted current deviation signals. The direction to a fault is determined by an amplitude comparator technique which compares a discriminant value with a positive or negative threshold. Simulation studies on a three-phase power system model show that the direction to a fault is determined within the first few milliseconds following the inception of a fault. Studies over a wide range of faults and source impedance angles show that the proposed amplitude comparator technique performs better than an analogous phase comparator technique 相似文献
A directional comparison digital protection scheme has been implemented with a 16-b single-board computer at each end of a physical model of a transmission line, with communication between the two ends. The protection algorithm makes use of the fundamental frequency components of the deviation signals of the voltage and phase-shifted current. Software routines have been developed for fault monitoring, directional determination, and the trip/block decision. Graphics features incorporated in the software are explained. Tests for various faults conducted on the physical model of a double-circuit transmission line show that the direction to a fault is determined in 3 to 7 ms. The blocking features of the relay are demonstrated 相似文献
International Journal of Coal Science & Technology - The lignite samples collected from Giral lignite field of Barmer basin have been subjected to petrological investigation. The data generated... 相似文献
A green atom‐economical method for the synthesis of highly functionalized 1‐amino and 1‐carbon substituted isoquinolines from the reaction of N′‐hydroxybenzimidamides and aryl ketoximes, respectively, with alkynes via pentamethylcyclopentadienylcobalt(III)‐catalyzed C H/N O bond activation is described. The external oxidant‐free annulation reaction uses the =NOH moiety in N′‐hydroxybenzimidamides or N‐aromatic ketone oximes as the directing group and internal oxidant. This first row transition metal‐catalyzed annulation serves as an efficient alternative for the synthesis of isoquinolines, as water is the only by‐product and expensive noble metals such as rhodium(III), iridium(III), palladium(II), and ruthenium(II) are not required. The reaction proceeds via C H activation, alkyne insertion, reductive elimination, and N O activation.
The copper(II)‐catalyzed decarboxylative coupling reactions of arylglyoxylic acids with isatins afford 4H‐benzo[d][1,3]oxazin‐4‐ones via decarbonylation and concurrent C–N, C–O bond formation.