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1.
The results of studying heating deformation and creep are described for two systems: electrocorundum — α-Al2O3 — phosphate binder and electrocorundum — pyrophyllite — phosphate binder. It is shown that composites with H3PO4 experience less deformation than composites with the alumochromium-phosphate binder, whereas using pyrophyllite instead of aluminum oxide increases creep deformation due to the presence of the liquid phase in the material. The effect of technological factors is investigated. __________ Translated from Novye Ogneupory, No. 6, pp. 58–62, June, 2007. Continuation. See beginning in Vol. 48, Nos. 1–2, 2007.  相似文献   

2.
The heat insulating layer of an aluminum electrolyzer is shown to become gradually impregnated with sodium and fluoride compounds. Vermiculite, while subjected to deep dehydration, enters into reaction with electrolysis products, which resulted in damage to the refractory chamotte layer. The saturation with gaseous compounds proceeds along the cleavage plane of vermiculite. Sodium tetrafluoraluminate is shown to form under the electrolyzer’s service conditions. Alongside the pure fluorides, complex fluorides of variable composition have been identified. Fluorides and metallic aluminum have been shown to form by condensation and disproportionation of lower fluorides. Electric corrosion is suggested as a factor affecting the structural integrity of the electrolyzer’s casing. __________ Translated from Novye Ogneupory, No. 1, pp. 11–17, January, 2006. For Parts 1–3, see Novye Ogneupory, Nos. 3, 5 and 9, 2005, respectively.  相似文献   

3.
The compositions of glasses formed in the process of operation of an aluminum electrolyzer, the lowest content of aluminum at which the glass is separated into aluminosilicate and oxyfluoride components, and the temperatures of softening and of formation of drops of titanium-bearing glasses composition close to the glass in ShPD-45 refractory (with an additive of mullite-corundum chamotte) are determined. It is shown that the oxyfluoride glasses consist of both a silica skeleton and a corundum skeleton. The titanium-bearing glass phase can hinder penetration of aggressive gaseous byproducts of electrolysis. __________ Translated from Novye Ogneupory, No. 12, pp. 10–12, December, 2007. Parts 1 and 2 of the paper appear in “Novye Ogneupory” Nos. 9 and 10 of 2007.  相似文献   

4.
Specimens of post-service ShA-5-grade chamotte refractory are analyzed for total elemental aluminum and silicon. Products of the electrolysis of cryolitic melt Na (gas), AlF, Al2O, and, possibly, Na2F are shown to diffuse through pores of the carbon refractory bottom lining blocks of an aluminum electrolysis cell. The lower compounds and Na(gas) as they reach the refractory layer enter into a reaction with the refractory material. The Gibbs free energy of hypothetic reactions in the Al - Si - O - F - Na system involving a gas phase has been calculated. It is inferred that the performance characteristics of the ShA-5 refractory fail to meet standard operational requirements. __________ Translated from Novye Ogneupory, No. 5, pp. 24 – 26, May, 2005.  相似文献   

5.
The pore formation process and the phase composition of the products of combustion of the Ti—Si—Al—C system were studied. The structure of Ti5(Si,Al)3C0.6 single crystals formed in small amounts was determined. The dependences of the burning rate and elongation of the samples on their density and the gas pressure were determined. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 2, pp. 53–60, March–April, 2006.  相似文献   

6.
Results for specimens of the refractory lining sampled from the bottom of an aluminum electrolysis cell with a service life of 3.5 years examined by methods of petrography, chemical analysis, and electron probe x-ray microanalysis are reported. The main products of conversion are sodium aluminosilicates, sodium silicates, a glassy phase of variable composition, oxyfluoride glasses, and eutectics. Some of the specimens analyzed are high in β-alumina (20 – 50%). Fluorides are represented by NaF (about 7%), cryolite Na3AlF6 (2 – 5%), malladrite Na2SiF6 (2%), and NaF ⋅ MgF2 (1 – 2%), and the metallic phase, by aluminum (2 – 7%) and ferrosilicon (3 – 10%). The apparent density of the used refractory material is 2.5 – 2.62 g/cm3. __________ Translated from Novye Ogneupory, No. 3, pp. 13 – 17, March, 2005.  相似文献   

7.
Proton magnetic resonance spectra of beryllium hydroxide β-Be(OH)2 and products of its thermal decomposition are studied at room temperature and 123 K. It is shown, based on these spectra and differential thermal analysis and x-ray diffractometry data, that, heated to above 500 K, β-Be(OH)2 decomposes into a finely dispersed BeO and H2O to convert finally to an amorphous beryllium oxyhydroxide. At above 600 K, a crystalline BeO is formed involving dehydration of the finely dispersed BeO and amorphous oxyhydroxide phase. __________ Translated from Novye Ogneupory, No. 7, pp. 39–41, July, 2005.  相似文献   

8.
Data are provided for laboratory studies of the resistance of aluminosilicate refractories to the action of commercial electrolyte. It is established that refractory ShPDM-45, prepared using a mullite-corundum chamotte, is most resistant to electrolyte action. Results are provided for studies in the change of mineral composition and phase transformations in aluminosilicate refractories during reaction with commercial electrolyte. It is shown that long-prismatic titanium-containing mullite is more resistant to the action of the fluoride ion than short-prismatic material. __________ Translated from Novye Ogneupory, No. 10, pp. 26–32, October 2007. Part 1 of the article was published in Novye Ogneupory No. 9 (2007).  相似文献   

9.
Results are provided for a study of the kinetics and mechanism of phase transitions (PT) of gibbsite during heat treatment in air and in water vapor (in the range 170–550°C) by iso-and non-isothermal thermogravimetry, x-ray-phase analysis (XPA), transmission electron microscopy (TEM), nuclear magnetic resonance in 27Al nuclei (NMR 27Al), and chemical analysis. It is shown that PT of gibbsite in air there are two interconnected transitions that occur in parallel: gibbsite → boehmite (γ-AlOOH) and gibbsite → x-ray amorphous Al2O3 that are realized by a topochemical mechanism. In water vapor gibbsite only experiences transition to boehmite (PT-3) that occurs by a dissolution — precipitation mechanism. Apparent activation energies for the PT that occur are determined. __________ Translated from Novye Ogneupory, No. 10, pp. 63–67, October 2007.  相似文献   

10.
The distribution of biomarker hydrocarbons in the thermolysis and thermocatalysis products of oxygen-containing compounds (possible petroleum hydrocarbon precursors) was studied by gas chromatography-mass spectrometry. It was found that n-alkylcyclohexanes and steranes were generated in the course of thermolysis along with expected hydrocarbons—n-alkanes and isoprenes, which resulted from the loss of a functional group. In this case, the molecular-weight distributions of n-alkanes and n-alkylcyclohexanes correlated well with each other. In the course of thermocatalysis, the homologous series of n-alkanes and n-alkylcyclohexanes were also generated; however, an n-alkylcyclohexane distribution maximum had an even number of carbon atoms in the molecule (C18). It was experimentally found that the sterane fragments of oxygen-containing compounds formed upon thermolysis were thermodynamically unstable; this was supported by the formation of biological C27–C29 5α, 14α, 17α, 20S, and 20R and 5β, 14α, 17α, and 20R (coprostane) steranes as a result of thermolysis. Unlike thermolysis, all of the four epimers of regular C27–C29 (5α, 14α, 17α, 20S, and 20R and 5α, 14β, 17β, 20S, and 20R) steranes were formed as a result of thermocatalysis. It was found that the relative distribution of biomarker hydrocarbons in the thermolysis products of various oxygen-containing compounds largely reflected the structure of the parent organic substance, as compared with that upon thermocatalysis in the presence of active aluminosilicate.  相似文献   

11.
The results of an integrated study of external factors on wear resistance of periclase-chromite refractories in vacuum chamber lining are discussed. It is established that the mineral composition and structure of magnesian-spinellide refractories are the least liable to transformations. __________ Translated from Novye Ogneupory, No. 9, pp. 35–38, September, 2006.  相似文献   

12.
Erosion is considered for zirconium refractories in a hot gas flow. Additional ionization of the flow with 1% of atomic potassium in terms of the mass of combustion products increases the wear, and also causes diffusion in the structure. Consequently, local accumulations of carbon occur in the intergranular zones of a coarse-grained specimen. __________ Translated from Novye Ogneupory, No. 1, pp. 49–53, January, 2008.  相似文献   

13.
It is confirmed that an aluminum electrolyzer casing is subject to electrochemical corrosion. It is established that on reaction of electrolyzer associated gaseous products with the electrolyzer casing there is formation of fluorides of bi- and trivalent iron, and also iron fluorides of non-stoichiometric composition. It is shown that the fluoride layer formed does not protect the casing surface from further corrosion. In order to protect the electrolyzer casing it is necessary to fasten a refractory barrier layer. More reliable heat insulation should be used in order to maintain the optimum casing heating temperature. Translated from Novye Ogneupory, No. 1, pp. 39 – 42, January 2009.  相似文献   

14.
It is established that Si3N4—SiC composites with a mass content of SiC 5–60% and a dominating content of the β-modification of silicon nitride can be produced by interaction of the components in the Si—C—N2 system in the combustion regime. It is found that the fraction of α-Si3N4 can be increased by diluting the starting mixture with the end products, but this leads to the occurrence of a certain amount of unreacted silicon in the products. It is shown that the use of chemical activation allows one to perform a single-stage synthesis of Si3N4—SiC composites with any contents of the individual components (from 0 to 100%), including pure carbide silicon. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 56–62, September–October, 2006.  相似文献   

15.
It is established that the sequence and intensity of polymorphic transformations of silica raw material on heating in the range 1000 – 1200°C are explained by features of its chemical and phase composition. Differences in structure and phase changes determine the different degree of activity for this raw material during synthesis of silicate compounds. Translated from Novye Ogneupory, No. 1, pp. 18 – 22, January 2009.  相似文献   

16.
An economic concept of protecting the atmosphere from dust exhausts in refractory production is proposed. The efficiency of measures intended to decrease atmospheric pollution is considered at two levels: primary level — lowering the damage caused to the environment by decreasing dust exhausts: secondary — an integrated socioeconomic effect (improving the living standard of the population and increasing national wealth). A procedure is recommended for estimating the economic damage to company fixed assets caused by dust exhausts. __________ Translated from Novye Ogneupory, No. 7, pp. 63–65, July, 2006.  相似文献   

17.
A new water-soluble derivative of chitosan — chitosan oligoethylene oxide sulfonate — was synthesized. The ratio and concentration of reacting substances and temperature and duration of the chitosan modification reaction affect the composition and properties of the reaction products. The conditions that ensure a 100% yield of water-soluble chitosan derivatives were determined. Using potentiometric titration and IR spectroscopy, the formation of a new water-soluble chitosan derivative — oligoethylene oxide sulfonate — was confirmed. __________ Translated from Khimicheskie Volokna, No. 4, pp. 41–44, July–August, 2005.  相似文献   

18.
The technology of producing structural graphites and the product ranges of carbon products produced at the Chelyabinsk Electrode Works are described. __________ Translated from Novye Ogneupory, No. 1, pp. 26–29, January, 2007.  相似文献   

19.
The synthesis and properties of fused materials in the ZrO2 - SiO2 - CaO system (83.1 – 91.7% ZrO2, 0.3 – 9.2% SiO2, and 0.6 – 7.8% CaO) are reported. CaO-assisted stabilization of ZrO2 to yield a cubic modification is reached at a SiO2 concentration of ≤ 4.3%. The arc furnace technology developed can be used to fabricate crucibles, tubes, rings (of diameter 320 mm and height 310 mm), and other shaped components from high-zirconia refractory materials with more than 90% ZrO2. __________ Translated from Novye Ogneupory, No. 3, pp. 37 – 40, March, 2005.  相似文献   

20.
Contemporary solutions are presented for completion of a monolithic refractory lining for a heating furnace using products produced by OOO Keralit. __________ Translated from Novye Ogneupory, No. 3, pp. 80–83, March 2008.  相似文献   

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