Special features of heating and melting electrodes with an exothermic mixture in the coating

Experimental results show that exothermic reactions in the heating and melting stages of electrode coating take place when the coating contains more than 35% of the exothermic mixture. Data for the effect of the amount of exothermic mixture in the electrode coating on heating and melting of the electrodes are presented. The thermal balance of melting the electrodes with the exothermic mixture in the coating is calculated. The results show that the temperature of 1273 K at which the efficiency of the exothermic reaction is high is reached at a distance of approximately 1 mm from the electrode tip. It is confirmed that the addition of up to 53.4% of the exothermic mixture to the electrode coating increases the effective efficiency of heating the parent metal (η_m) from 0.715 to 0.815 and of the electrode (η_el) from 0.28 to 0.415.     

Probe measurements of the potential distribution in anisotropic semiconductor crystals and films

Expressions for determination of the electric potential distribution in rectangular anisotropic semiconductor samples are presented. Practically important cases of the samples’ localization on a metal, semiconductor, or dielectric substrate are considered.     

Logical and Information Models of the Processes of Maintenance of Boiler Installations of Chemical and Technological Systems

Theoretical Foundations of Chemical Engineering - The importance of the process of technical maintenance of boiler plants of thermal power plants of chemical production is substantiated....     

Long-Wave Infrared Focal Plane Arrays Based on a Quantum-Well AlGaAs/GaAs Structure with 384 × 288 Elements

The characteristics of focal plane arrays (FPAs) based on (quantum-well infrared photodetector) QWIP structures with 384 × 288 elements spaced at the intervals 25 μm are investigated. The difference in spectral and current–voltage characteristics is established for epitaxial QWIP wafers. The output signal is found to vary over the area of photosensitive elements with gradients in different directions. The photoelectric FPA parameters depend strongly on the temperature of the cooled assembly and the bias at the photosensitive element. The noise-equivalent temperature difference is 30 mK at the frame rate 120 Hz and the cooled assembly temperature 65 K.     

Photoelectric characteristics of focal plane arrays based on epitaxial layers of indium antimonide deposited on a heavily doped substrate

Photoelectric characteristics of a 320 × 256-element focal plane array (FPA) with a pitch of 30 μm, whose photosensitive element is formed in the InSb epitaxial layer deposited on a heavily doped substrate, have been investigated. For a relative aperture of 1: 0.94 and an integration time of 1.46 ms, the mean value of the noise-equivalent temperature difference is 10.5 mK, the percentage of defective elements is 0.12%, and the correction time is more than 3 h. The FPA has been compared to similar commercial devices based on bulk InSb.     

Nanostructure Growth in the Ga(In)AsP–GaAs System under Quasi-Equilibrium Conditions

Semiconductors - The formation of nanostructures on the surface of GaAs under quasi-equilibrium conditions in a quasi-closed volume from saturated phosphor and indium vapors in the presence of a Au...     

Graphite structural transformations during intercalation by HNO3 and exfoliation

Expandable graphite of two types was synthesized by (1) hydrolysis of graphite nitrate of II stage and (2) anodic polarization of graphite in 60% HNO₃. Exfoliated graphite samples were produced by thermal shock of expandable graphite samples in air at 900 °C. A comparative study of microstructural distinctions of both expandable and exfoliated graphite samples was carried out using X-ray diffraction, Raman spectroscopy, electron energy loss spectroscopy and high resolution transmission electron microscopy.     

Molding Silicon Carbide Articles by Freezing Aqueous Slip

Molding silicon carbide articles by freezing aqueous slip is considered. The freezing conditions are determined. The slip composition is selected. Firing in a nitrogen-hydrogen medium at 1850°C made it possible to obtain samples whose properties are typical of this material.     

Thermophotovoltaic cells based on In0.53Ga0.47As/InP heterostructures

Reflection of infrared radiation from n-InP substrates with a rear MgF₂/Au mirror is investigated in the wavelength range 1000–2200 nm. It is found that the reflectance weakly depends on substrate thickness and free-carrier concentration in the (0.1–6) × 10¹⁸ cm^?3 range. Thermophotovoltaic cells based on the InP/In_0.53Ga_0.47As lattice-matched heterostructure of p-n and n-p are fabricated by liquid-phase epitaxy and Zn and P diffusion from a gas phase. The characteristics of p-n and n-p thermophotovoltaic cells with an identical configuration of the contacts of 1 cm² area are determined. These characteristics are the open-circuit voltage U _oc = 0.465 V, the filling factor FF = 64% at the current density of 1 A/cm², and the reflectance R = 76–80% for wavelengths longer than 1.86 μm.