Phosphate-bonded refractory coatings

Conclusions A study of the adhesion and cohesion strength of refractory coatings based on oxides of titanium, zirconium, hafnium, silicon; nitrides of hafnium, boron, silicon; mullite, magnesia spinel, zirconates of calcium, barium, strontium; disulfide and disilicide of molybdenum, and calcium titanate, using phosphate bonds, established the optimum compositions for the coatings for the following alloys: 1Kh18N9T, Él-703, ÉP-99, VT-9, OT-4, ÉI-961, Br.Kh08 bronzes, molybdenum and graphite.Results are given for the working temperatures, shear strengths, and thermal-shock resistance of the coatings and also the electric conductivity and temperature conductivity of some compositions. The refractory coatings with phosphate bonds that were developed are recommended for use in high-temperature installations in the temperature range 1000–1800°C.Translated from Ogneupory, No. 4, pp. 50–54, April, 1973.     

Statistical Product Selectivity Modeling and Optimization for γ-Al2O3-Supported Cobalt Catalysts-Based Fischer–Tropsch Synthesis

The statistical selectivity models were developed for four different Fischer–Tropsch synthesis product range, including methane (CH₄), light olefins (C₂=C₄), light paraffins (C₂–C₄), and long-chain hydrocarbons (C₅₊), based on the experimental data obtained over thirteen γ-Al₂O₃ supported cobalt-based catalysts with different cobalt particle and pore sizes. The input variables consist of cobalt metal particle size and catalyst pore size. The cubic and quadratic polynomial equations were fitted to the experimental data, however, the mathematical models were subjected to model reduction for the enhancement of model adequacy, which was investigated through ANOVA. The multi-objective optimization revealed that the maximum C₅₊?selectivity (84.150%) could be achieved at the cobalt particle size and pore sizes of 14.764 and 23.129 nm, respectively, while keeping the selectivity to other hydrocarbon products minimum.

Graphic Abstract

     

The Formation of Hollow Lead Structures on the Surface of PbSe Films Treated in Argon Plasma

Conditions for ion sputtering of a PbSe/CaF₂/Si(111) epitaxial system in high-density inductively coupled plasma of high-frequency low-pressure discharge in argon have been established that ensure the formation of submicron-sized hollow lead structures on a lead-selenide surface. The surface was plasma-treated for time periods within 60–240 s at low energy (20–30 eV) of Ar⁺ ions, which is close to their sputtering threshold energy. The properties of the obtained material were studied by the techniques of scanning electron microscopy and energy-dispersive X-ray microanalysis. It is shown that the characteristic size, shape, and density of surface structures can be varied within broad limits depending on the time of plasma treatment and temperature of the material surface. Physical processes responsible for the formation of hollow lead structures under the proposed conditions of plasma sputtering are considered.     

Simulation of the effects of deep grooving in silicon in the plasmochemical cyclic process

The results of computer simulation of the effects of the formation of deep groove profiles in silicon during the cyclic etching-passivating process in SF₆/C₄F₈ plasma are reported. It is shown that the groove profile varies under variations in one of the basic parameters of the process, the etching-passivation time ratio at different probabilities of the reactions of etching and the deposition of a fluorocarbon film. The sensitivity of the model to these parameters is determined. Grooves with different tilt angles of walls are simulated, and the opportunity for controlling the groove profile by varying the parameters during grooving is shown.     

An automated laser thermometer for studying plasma processes in the microtechnology

The design and characteristics of an automated temperature sensor of dielectric and semiconductor substrates in apparatuses for film deposition and etching of microstructures are considered. The temperature is measured via the laser interference thermometry technique as wavelengths of 0.633 and 1.15 μm of a He-Ne laser. A signal-to-noise ratio of ～30 dB attained in the system is such that the device is sensitive to a change in the substrate temperature of 0.01 K. The heating and cooling of the wafer are recognized automatically and displayed via a graphic interface in real time. An interferogram recorded during substrate heating or cooling, the time dependence of the temperature after the discharge initiation, and the temperature dependence of the substrate-heating power are displayed on the monitor. For 0.5-mm-thick silicon substrates, the measurement range at a wavelength of 1.15 μm extends from cryogenic temperatures to 650 K.     

Fabrication of 0.5-μm structures by dry electron lithography and anisotropic plasma etching

A method for the fabrication of submicron (~0.5 μm) structures is presented. It includes the plasma formation of a three-layer mask, electron-beam exposure, plasma development, and anisotropic plasma etching of a resist and silicon oxide. The development in a fluorine-containing plasma forms the negative image of the exposed pattern (a set of parallel strips). The minimum resolution was 0.5 μm at the exposure dose 8 x l0^-4C/cm². The minimum exposure dose at which separate lines are developed was equal to 1 x 10^-4 C/cm²     

Magnetoelectric interactions in BiFeO<Subscript>3</Subscript>, Bi<Subscript>0.95</Subscript>Nd<Subscript>0.05</Subscript>FeO<Subscript>3</Subscript>, and Bi<Subscript>0.95</Subscript>La<Subscript>0.05</Subscript>FeO<Subscript>3</Subscript> multiferroics

The technology of ceramic BiFeO₃, Bi_0.95Nd_0.05FeO₃, and Bi_0.95La_0.05FeO₃ multiferroics is described. The room-temperature magnetization, magnetoelectric (ME), and magnetodielectric (MDE) effects in these compounds have been studied. It is established that even a small fraction (x = 0.05) of rare-earth additives (La, Nd) to bismuth ferrite not only enhance its magnetic properties, but also significantly influence the ME and MDE effects. The dependence of the ME effect on the frequency of modulation of the alternating magnetic field in Bi_0.95Nd_0.05FeO₃, and Bi_0.95La_0.05FeO₃ is more pronounced than in pure BiFeO₃.     

Changes in the conductivity of lead-selenide thin films after plasma etching

The conductivity of epitaxial n- and p-PbSe thin films after dry etching in radio-frequency highdensity low-pressure inductively coupled argon plasma at a bombarding-ion energy of 200 eV is studied. It is shown that the observed changes in the conductivity can be adequately interpreted in the context of the classical model of the generation of donor-type radiation defects and that the processes of post-irradiation vacuum annealing result in the removal of such defects. The mean free path of charge carriers in p-PbSe films is determined within the context of the Fuchs–Sondheimer theory. It is found that, at room temperature, this parameter is 16 and 32 nm for the specularity parameter 0 and 0.5, respectively.     

Multiband current transformers

The design and principle of action of the new multiband transformer of a current is considered in which the expansion of the top range of measurements is carried out by creation against a magnet driving force in the closed core.