Factors of large graphite crucible life

Production methods used to prepare graphite crucibles with high operating properties are considered: use as a filler of good graphitizing acicular coke, vibration molding of the original coke mix, use of production cycles for impregnation with medium temperature coal-tar pitch — firing, firing of compacted billets in metal containers, graphitization of fired billets in graphite cylinders. The last two production methods make it possible to reduce the temperature drop throughout the volume of a billet during heat treatment, and as a consequence to reduce crack development to a minimum as a result of reducing thermal stresses. All of the production methods recommended may be entirely accomplished in existing electrode plants and may be used to increase markedly the quality crucible graphite. It is possible to achieve a quality for these materials at the best world level. Translated from Novye Ogneupory, No. 8, pp. 28–33, August 2008.     

Highly resistant dispensing nozzles based on zirconium dioxide for profiled CBCM. Part 1. Structure and physicomechanical properties of materials based on zirconium dioxide for producing CBCM dispensing nozzles

Technology is developed for preparing refractory components made of partially stabilized zirconium dioxide using an isostatic compaction press. Technology is provided for manufacturing dispensing nozzles using combined and separately stabilized zirconium dioxide, and also indices of the refractories obtained and imported materials are compared. __________ Translated from Novye Ogneupory, No. 3, pp. 127–131, March 2008.     

Total and Fractional Performance of Granular Dust Traps in Refractory Production

Methods are proposed for designing interpolation models for the preliminary determination and subsequent forecasting of general and fractional breakthrough coefficients for dust used with granular filters, as employed in energy-saving and high-performance dust trapping from technological gases and ventilation discharges in refractory production. The models are supplied with nomograms, which makes them widely suitable for experts working in environmental protection at refractory-producing organizations. The main factors are identified that influence the performance. The results are of interest to experts in related areas of industry such as building materials and engineering ceramics and so on. Translated from Novye Ogneupory, No. 4, pp. 64–67, April, 2008.     

Generalized model of the formulation of the required composition of pitch-coke mixtures

Known methods of calculating the required compositions of pitch-coke mixtures in producing large graphitized electrodes are not widely used [1, 2]. This may be attributed to the multivariance of the problem, the probabilistic character of the technological operations, the lack of well-founded optimization criteria, and the sensitivity of the characteristics of the product to variation in the parameters of the initial materials and their ratios in the mixture. The only means of solving the problem is physical modeling, taking account of current computer capabilities.     

Evaluating coking resources. 2. State standard GOST 25543-88 as a coding system for coal and coal mixtures in evaluating their technological properties

The codification of coal in State Standard 25543-88 is compared with the international codification of coal of medium and high rank. The ranking of coking coal on the basis of State Standard GOST 25543-88 is evaluated.     

Tellurium clusters in channels of the porous silica ZSM-11

The distribution and structure of tellurium nanoclusters synthesized in crystal channels of the porous silica ZSM-11 are investigated using the maximum-entropy method and the Rietveld analysis. It is shown that the intercalated tellurium atoms are arranged in channels of the ZSM-11 zeolite not randomly but in the form of scraps of infinite chains similar to those observed in massive tellurium. The distances between the nearest neighbor tellurium atoms vary in the range 2.53(4)–2.70(3) ?. The clusters Te₄ are formed at the intersections of channels in the structure. These clusters have the form of distorted tetrahedra in which the tellurium atoms are separated by distances of 2.53(4) and 2.90(4) ?. Original Russian Text ? A.E. Lapshin, Yu.F. Shepelev, Yu.I. Smolin, E.A. Vasil’eva, 2008, published in Fizika i Khimiya Stekla.     

Noise–Power Optimization of Incremental Data Converters

Incremental data converters (IDCs) are useful in instrumentation and measurement applications, where low-frequency analog signals need to be converted into digital form with high accuracy and low power dissipation. They are particularly well suited for applications where a single analog-digital converter is multiplexed between many channels. This paper proposes an exact design methodology for IDCs, which optimizes the signal-to-noise ratio of the converter under practical design constraints. The process also allows the designer to apportion the noise budget in an arbitrary manner between thermal and quantization noise. The design process is illustrated by an example which describes the optimization of a third-order multiplexed IDC.