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The Borovichi Refractories Combine developed and continues to make and use high-alumina (calcium- aluminate) cements Cembor-73 and Cembor-70 to produce refractory concretes and concrete products. This article discusses the main issues attending the production, composition, and properties of high-alumina cements of the Cembor series. These cements are compared to other Russian-made cements and similar cements made abroad. Recommendations on the use of cements Cembor-3 and Cembor-70 are made based on data on their composition and properties.

Comparative studies of the properties of calcined fireclay articles and articles made of low-cement refractory concretes (LCRC), fired at different temperatures and non-fired, used for the masonry of the bottom structure of tank glass furnaces (bottom block) have been performed. Experimentally obtained data on the thermophysical properties, CLTE, glass stability of articles made of LCRC and calcined fireclay articles are presented. It is shown that fired fireclay articles are desirable to increase the service life of the furnace.

Concrete examples of new technological and engineering designs of effective refractory materials for use in metallurgy and the glass industry are presented. It is shown that the OAL Borovich Refractory Combine has expanded the degree of diversification of its production activity not only through the development of new types of products, but also through the startup and operation of services that are new for the enterprise, such as engineering and bench pre-assembly of the bottom and other elements of glass making furnaces.

“BKO” JSC has perfected an assembly-stand technology for the elements of a glass-making furnace, first and foremost, the furnace bottom. Coordinated studies were performed to ensure that the accuracy of the stand meets the requirements: a stand with planarity deviations ± 0.5 mm was designed and built, the preparation technology (cutting and grinding) for the block articles for the assembly stand with minimum admissible deviations (linear dimensions ± 0.25 mm; inclinations less than 0.2 mm) was perfected, and the assembly stand technology itself was perfected. The technology developed was used to assemble other elements of the furnace: feed pans of the glass-forming machines, regenerator arches, and loading hoppers. An assembly stand makes it possible decrease substantially the assembly time of a glass-making furnace, lower the construction costs, and develop favorable conditions for laying other elements of the furnace, all which taken together increase the service life of a furnace.

One of the main directions of diversification at BKO JSC is manufacturing products for the glass industry. Aside from the production of the conventional aluminosilicate refractories, BKO JSC develops and produces new types of refractory materials, performs preliminary bench assembly of the structural elements of furnaces (bottom, loading-hopper arch, subchecker arch, feeder troughs). Specialists at BKO JSC provide engineering services for designing individual units of a glassmaking furnace using the BKO’s materials. All design solutions are accompanied by recommendations for performing the lining work and putting linings into the working regime.

It is shown that use of a multichannel USD-60-5 defectoscope makes it possible to reduce considerably the time for monitoring a single refractory object. It is established that with a relative amplitude of more than 50% a glass beam grade ShSU-33 in the measurement zone has physical indices exceeding the standard specification. Results are given for statistical treatment of measurements of a fired glass beam ShSU-33 by a Bstat program.

To reveal the distribution of evident and latent electrically active defects of various types and different scales that affect the photoresponse of Cd1 − xZnxTe alloys (x = 0.05–0.2), it is suggested to compare local photoelectric signatures U–I(y)f, λ of various segments of the sample (U is the testing voltage, I is the photocurrent, y is the coordinate, λ is the wavelength, and f is the frequency of the testing signal), while, for the search of local instabilities of photoresponse, totality of integrated signatures U–I(Δy)f, λ is most suitable. It is shown for the first time that the multiple scale and coordination of the fields of defects and acting field generate the spectral features of the photoresponse (reconstruction of the spectra and manifestation of latent photosensitivity bands), which are most completely and integratively reflected in signatures of the photocurrent spectra I(λ)–dI/dλ.

Results are provided for the development and introduction into production of high-alumina objects of different grades based on andalusite. Physiochemical indices, and fields of application for objects in various heating units are indicated.

In the OAO Borovich Refractory Combine production has been assimilated for a complete set of refractories for continuous steel casting, i.e. from a pipe for protecting a stream of metal to a submerged nozzle. In technical and life characteristics the products correspond to that of world analogs, they provide accident free steel pouring, make it possible to reduce the specific consumption of refractories per ton of steel, to increase CBCM productivity, to reduce billet scrap, and to reduce steel cost.

Borovichi Refractory Plant JSC has performed a complex of works on manufacturing fireclay block parts for the lower structure of glass-making furnaces. The characteristics of the technology for producing the parts and the process line as well as upgrading technological equipment and guaranteeing product quality are examined. The physical and chemical properties of ShSU-33 and MLS-62 parts and the advantages of such parts over similar products from other manufacturers are presented.

I(t)-dI/dt phase diagrams obtained under local and integral photoexcitation have been used to investigate the stability of the dynamic photoresponse of Cd0.9Zn0.1Te crystals containing two-dimensional structural defects and defect complexes. The results demonstrate that the diagrams shed light on the development and loss of the dynamic stability of the photoelectric response under photoexcitation with rectangular light pulses in combination with linear heating in the temperature range 293–450 K.

The acute competition on the world market of ferrous metals calls for taking measures designed to raise the competitiveness of the domestic metallurgical sector. Domestic refractories do not fully meet the constantly increasing service requirements of the metallurgical sector. Until recently the resistance of domestic refractories used for pouring steel on machines for continuous steel casting (MCSC) was 1.5 – 2 times lower than that of imported refractories. This circumstance leads to excessive consumption of refractories and increased rejection of steel slabs when the casting process has to be interrupted for replacement of submersible nozzles or tundish ladles and for the wear of monoblock stoppers. To satisfy the growing requirements of metallurgists, the Borovichskii Refractory Works (BRW) by force of the company specialists and invited researchers keeps upgrading the technology of refractories in order to improve their physicochemical properties and, accordingly their resistance. CARBON-OXIDE PRODUCTS FOR STEEL MELTING

The engineering center at Borovichi Refractory Corporation has researched the optimization of composition for periclase-spinel components for lining the sintering zone in a rotating oven for firing cement clinker. The best composition and the best ratios between the additives have been established for the addition to the finely ground material, and the composition has been determined together with the best amount of temperature compensator, which is needed to improve the thermomechanical properties of the components and give preset working-life characteristics.

OAO Borovichi Refractory Plant has developed a number of new forms of product for lining the socle of an electrolyzer for obtaining primary aluminium. Results are provided for research on thermal insulating vermiculite products of the ITOM (integral heat insulation refractory materials) series and barrier materials: dense fired refractory articles BorAluBar, mastic for filling joints BorAluPlast, and dry barrier mixture BorAluMix. Newly developed products will make it possible to propose to aluminum producers a comprehensive solution for lining the electrolyzer cathode with contemporary refractories and thermal insulating materials with a high technical resource. Use of the materials will make it possible to prolong electrolyzer service life by several degrees.

The spectrum and mode shapes of the natural elastic vibrations of disk-shaped ZnSe crystals are studied. Twin modes are identified which are closely related to the stress-strain state of the material.

Modifications in the structure and electrophysical properties of ZnSe crystals subjected to a high alternating electric field of industrial frequency are investigated. It is established that such an action changes their defect structure and dielectric parameters. The latter exhibit different dependences on temperature and photoexcitation wavelength. The modifications are caused by ionic conduction, which is associated with local anomalies in the electric and elastic subsystems of the crystals.

To meet the increasing stringent requirements placed on the quality of rolled products, technologists seek to develop techniques that would allow the metal to be cleaned of nonmetallic inclusions, impurities of oxygen, hydrogen, etc.

It was found that the specific features of the photodielectric response of CdTe crystals grown from the melt are determined by ensembles of macroscopic growth defects. The analysis of diagrams ɛ*(λ) and ɛ*(X), which characterize the dependences of the complex dielectric constant on the wavelength and coordinates, as graphic images of sequences of induced states of the crystal was carried out. It was demonstrated that such analysis allows for the identification of the ensembles of macroscopic defects, which are the sources of internal fields.

The distribution of growth defects of various types arising in zinc selenide crystals grown from the melt under highly nonequilibrium conditions determines different, but interrelated metastable states of samples cut from different parts of the same ingot. The characteristic features of the dielectric response of these states, as well as of the states induced by an external action, are established.

The transport properties of GaAs/AlGaAs submicron rings with split gates in the conditions corresponding to the ring resistance R SD τ;h/e 2 are studied. Oscillations of R SD as a function of the gate voltage V G are experimentally observed. The oscillations are caused by the single-electron charging of two triangular conducting regions into which the ring is divided in the tunneling regime.

Data on interactions in the ZrO2 - Fe2O3 system stabilized by oxides in a high-temperature form at 1750°C are obtained. Of all zirconia-based compositions, only magnesium-zirconium cubic solid solution enters into an active reaction with Fe2O3 to yield MgFe2O4. The solid solutions formed by ZrO2 with oxides of yttrium, neodymium, and calcium resist degradation by attack from Fe2O3; part of iron oxide undergoes dissolution in cubic ZrO2.

Data are presented on the spectral dependence of steady-state photoconductivity for Cd1 - xZnxTe (x = 0.12–0.15) crystals grown under different conditions. The results indicate that the full width at half maximum of the near-edge photoconductivity peak is sensitive to the state of native structural defects and can be used to assess the quality of Cd1 - xZnxTe crystals and their applicability in high-resolution gamma detectors.

The Borovichi Refractory Plant has organized the production of new advanced refractories, including graphite-containing articles for continuous casting of steel, a variety of mullite-corundum articles, mortars, and refractories for lining blast furnaces. The prospects for refractory production are considered. Properties of the new refractories and data on their use in the metallurgical industry are presented.

A method of scanning photodielectric spectroscopy of crystals has been suggested. It is based on the measurements of small increments of the real Δe′ and imaginary Δe″ parts of effective dielectric permittivity at a smooth variation of the photoexcitation wavelength λ. The spectral functions Δe′(λ) and Δe″(λ) are presented in a complex plane, that is, in parametric view, and their characteristic points are determined. Application of this method on Cd1−xZnxTe crystals showed a possibility of determining the energy position of the localized states generated in the forbidden zone by the intrinsic structure defects.

The transport properties of delta -GaAs (Si) at high temperatures were studied using the 'mobility spectrum' technique. Strong changes in the subband occupancies were observed in a low-doped sample (ND=1.5*1012 cm-2) as the temperature increased from 77 K to 300 K while in a high-doped sample (ND=5.0*1012 cm-2) these changes were small. For an explanation of the observed behaviour with temperature Poisson's and Schrodinger's equations were solved self-consistently. The mobility of the lowest subband (i=0) was found to be relatively independent of temperature while the mobilities of the higher subbands (i>0) decreased with increasing temperature in both low- and high-doped samples. At close to room temperature, the conductivity of the delta -structures can be described well by a two-carrier model where the first group consists of the electrons of all the higher subbands having approximately equal mobilities.

It was demonstrated that plots of the imaginary part vs. the real part of the complex dielectric constant ɛ*(λ) in relation to a wavelength for Cd1−xZnxTe crystals grown from the melt show a series of special features that were not observed in the plots for other II-VI compounds. These features were found to be related to a variety of growth defects and to the considerable influence of electric and elastic-stress fields produced by these defects on the dielectric properties of the crystals.

The real (e") and imaginary (e"") parts of the complex dielectric permittivity of Cd1 – xZn x Te (x= 0.1–0.2) crystals are measured as a function of temperature and frequency. The e""-vs.-temperature data show a maximum, and e" rises rapidly at about the same temperature. This behavior is interpreted in terms of compositional fluctuations, structural defects, and the associated internal electric fields.

Optical transitions in delta-doped “sawtooth” n-i-p-i superlattices with various periods are studied experimentally in this paper by photocurrent (PC) and photoreflectance (PR) spectroscopy. The exponential tail of the PC below the band gap ɛ g and oscillations of the PR above ɛ g are due to the Franz-Keldysh effect caused by the homogeneous built-in electric field E in the superlattice. When the period of the superlattices decreases, a monotonic increase of the low-energy wing length and of the above-band gap oscillation period is observed, due to the rise of E . Not only superlattice built-in electric fields but also weaker fields of the buffer layers contribute to the PR spectra. It is shown that different contributions to the PR can be separated experimentally using different lifetimes of the photogenerated electrons and holes. The analogy between the Franz-Keldysh effect in semiconductors and the total reflection of light in optics is discussed.

Photoluminescence spectra of δ-p-doped GaAs structures of different doping levels are studied experimentally. It is found that set of PL bands observed in δ-p-doped samples recently is regularly broadened with doping concentration increase due to appearance of additional low-energy bands and their subsequent red shift at higher doping levels. A red shift of the bands and a change of their relative intensities were caused also by excitation laser intensity decrease and/or temperature increase. These results confirm our previous assumption that the bands are due to radiative recombination of spatially separated photoelectrons with holes occupying size-quantization levels of δ-layer potential well.

Photocurrent and photoreflectance spectra of GaAs δ-doped sawtooth superlattices of various periods are studied experimentally. Both the monotonic exponential part of the photocurrent tail below the bandgap and oscillations of the photoreflectance above the bandgap stem from the Franz-Keldysh effect in the SL built-in electric field. Regular changes of the tail as well as of the above-bandgap oscillations with decreasing SL period are explained by the strengthening of the built-in field. Impurity-related peaks are observed in the photocurrent spectra along with weaker shoulders; the latter may be tentatively attributed to optical transitions between quantum levels in the SL potential. Possible reasons for the blurring of quantum-confined optical transitions and for the impurity-related peaks are discussed.

It is shown that acoustic treatment of piezoelectric zinc selenide crystals by exciting strong natural elastic vibrations can specifically alter their photoelectric and other properties. Irreversible changes in the stressed-strained state of the crystals under this treatment are responsible for characteristic features in the spectral dependences of the permittivity e′(λ) and the dielectric loss coefficient e′’(λ). These dependences plotted in the form of e*(λ) diagrams on the complex plane and also the spectrum of natural elastic vibrations can be used to monitor the treatment process.

The preliminary results of an investigation of the structure and electrophysical properties of CVD-grown polycrystalline ZnSe are reported. A weak multicomponent texture is observed which bears upon the piezoelectric effect, the characteristic features of the electric polarization, and the characteristic elastic oscillations of samples of regular shape.

Results of an experimental study of the sinterability and resistance of zirconia-base materials stabilized by the method of plasmachemical synthesis to the action of the main components of metallurgical slags are presented. It is shown that the materials possess the highest resistance to the action of Fe2O3, Al2O3, and basic slag of the SiO2−CaO−Fe2O3 system, are less resistant to the action of acid slag of this system, and decompose actively under the effect of SiO2.

We discuss a method of scanning photodielectric spectroscopy of crystals which is based on the measurements of small increments of the real /spl Delta//spl epsi/' and imaginary /spl Delta//spl epsi/" parts of dielectric permittivity, which are induced by a smooth variation of the photoexcitation wavelength. The spectral dependences of both parts of the dielectric constant upon the light wavelength were presented in the complex plane. Application of this method on Cd/sub 0.9/Zn/sub 0.1/Te crystals showed a possibility of determining the energy position of the localized states generated in the forbidden zone by the intrinsic structure defects.

Results of installation of a technology for production of high-density chamotte refractories are presented. The properties of articles of different producers evaluated by 12 factors that determine structural, strength, and thermal characteristics are investigated.

Bauxites with 76% Al2O3 and 2.65% Fe2O3 were used to produce mullite refractories and mixtures for steel-teeming ladles. Tests in service have shown that the strength of these refractories is no worse than or comparable with that of refractories based on commercial alumina and Chinese bauxites.

In the quantum Hall regime in an electron interferometer we find magnetoresistance oscillations of various periods. This phenomenon is attributed to the interference of edge current states coupled by an impurity assisted tunneling.

We have observed a photovoltaic mesoscopic effect in quasiballistic electron interferometers in the quantum Hall regime. It was found that the mesoscopic E.M.F. generated by microwave radiation may be both periodic and aperiodic (h/e-and h/2e-oscillations) with magnetic field. We have established that this photovoltaic effect is the consequence of the interference of edge current states coupled by the impurity assisted tunneling.

Definite axial and radial temperature gradients created in the directed growth zone of zinc selenide single crystals lead to the formation of substructures. Such crystals may be used for manufacturing piezoresonators, special optical elements for measuring the power of transmitted laser radiation and modulating the latter.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new class of semiconducting structures with δ-doped layers and a high concentration of layered quasi-two-dimensional charge carriers is currently of great interest. On one hand these layers have interesting physical properties, on the other they are promising for practical applications [1].

Developpement d'une methode de calcul des profils de temperature et de contrainte dans la zone de travail d'un element chauffant tubulaire, en tenant compte de ses caracteristiques thermomecaniques, electrophysiques et thermophysiques

The dislocation structure of Ge layers has been studied by X-ray topography. The configuration, type, and density of dislocation are found to depend on temperature and growth rate. It is suggested, that the mechanism of the dislocation generation is based on the interaction of the growth steps with local inhomogeneities on the surface. The peculiarities of the dislocation behaviour in the growing layers in dependencce on the deposition temperature are discussed. [Russian Text Ignored.]