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.     

Exploring Internal Structure of Nanoporous Glasses Obtained by Leaching of Phase‐Separated Alkali Borosilicate Glasses

Mesoporous glasses – the leaching products of phase‐separated alkali borosilicate glasses – are widely used in fundamental research and practical applications. In this work, the option to control their internal mesopore structure by varying the conditions of microphase separation has been studied. Structure and transport characterization of a family of nanoporous glasses obtained under different conditions has been performed using a combination of several experimental techniques, including gas adsorption, nuclear magnetic resonance cryoporometry and diffusometry.     

Molar enthalpy of vaporization of ethanol-gasoline mixtures and their colloid state

Vapour pressure measurements are used to evaluate the enthalpy of vaporization of ethanol-gasoline mixtures. Partial molar values are also derived. The dispersed structure of ethanol-gasoline fuel is studied for the first time using the method of correlation spectroscopy of scattered light. A large range of dispersed particle sizes in different alcohol-gasoline systems is found. The dependence of the mean radius of drops on ethanol content is determined. It is found that coalescence phenomenon occurs in the systems when extra ethanol is added.     

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.     

Formation of Arrayed Droplets by Soft Lithography and Two-Phase Fluid Flow, and Application in Protein Crystallization

This paper presents an overview of our recent work on the use of soft lithography and two-phase fluid flow to form arrays of droplets. The crucial issues in the formation of stable arrays of droplets and alternating droplets of two sets of aqueous solutions include the geometry of the microchannels, the capillary number, and the water fraction of the system. Glass capillaries could be coupled to the PDMS microchannels and droplets could be transferred into glass capillaries for long-term storage. The arrays of droplets have been applied to screen the conditions for protein crystallization with microbatch and vapor diffusion techniques.     

Formation of droplets of alternating composition in microfluidic channels and applications to indexing of concentrations in droplet-based assays

For screening the conditions for a reaction by using droplets (or plugs) as microreactors, the composition of the droplets must be indexed. Indexing here refers to measuring the concentration of a solute by addition of a marker, either internal or external. Indexing may be performed by forming droplet pairs, where in each pair the first droplet is used to conduct the reaction, and the second droplet is used to index the composition of the first droplet. This paper characterizes a method for creating droplet pairs by generating alternating droplets, of two sets of aqueous solutions in a flow of immiscible carrier fluid within PDMS and glass microfluidic channels. The paper also demonstrates that the technique can be used to index the composition of the droplets, and this application is illustrated by screening conditions of protein crystallization. The fluid properties required to form the steady flow of the alternating droplets in a microchannel were characterized as a function of the capillary number Ca and water fraction. Four regimes were observed. At the lowest values of Ca, the droplets of the two streams coalesced; at intermediate values of Ca the alternating droplets formed reliably. At even higher values of Ca, shear forces dominated and caused formation of droplets that were smaller than the cross-sectional dimension of the channel; at the highest values of Ca, coflowing laminar streams of the two immiscible fluids formed. In addition to screening of protein crystallization conditions, understanding of the fluid flow in this system may extend this indexing approach to other chemical and biological assays performed on a microfluidic chip.