Permeability of porous materials

Calculated relations are proposed whereby the tortuosity of capillaries and the permeability of connected and disconnected porous materials can be assessed and determined. The relations allow for the percolation effect and closely fit the experimental data over a wide range of porosity. These expressions are recommended in cases where one is concerned with the determination of permeability in connected and disconnected pulverized and fibrous (i.e., ceramic) materials in engineering calculations. Translated from Steklo i Keramika, No. 2, pp. 23–25, February, 1997.     

Specific surface of powdered materials

A technique is proposed whereby the specific surface of powdered materials can be calculated using the viscous permeability of a powder bed. With it, rather rigorous consideration is taken of particle shape, pore space geometry, gas flow with slip, and molecular flow. The technique has much to commend it for fast determination of the specific surface when the dispersion of the starting materials for ceramics and the size reduction of the materials are monitored by observing the viscous permeability of a powder bed of the material involved. Translated from Steklo i Keramika, No. 4, pp. 19–21, April, 1997.     

Heat transfer accompanying a falling fluid flow

Translated from Atomnaya Énergiya, Vol 66, No. 1, pp. 18–22, January, 1989.     

Estimation and determination of the permeability of porous ceramics

The possibility of estimating the permeability of porous ceramic materials both with mercury and with gas liquid pore diagrams and based on model concepts concerning the porosity and average size of the constituent particles in the material was demonstrated. It was shown that the permeability of a porous material and the average pore radius can be directly determined with the linear segment of the reverse GLP curve and the capillary sinuosity can be calculated with it.     

Kerma factors for calculating the absorbed dose of 15–150 MeV neutrons

Conclusions A hybrid geometrically dependent model has been used to calculate the yield of charged particles in inelastic neutron—nuclear reactions involving elements which form part of the human tissue and are used in particle detectors, for primary nucleon energies up to 150 MeV. The hybrid model is found to give considerably better agreement with experimental data than the cascade—evaporative and cascade—exciton models in the entire energy range considered. The error in calculating the kerma factors using the hybrid model is estimated as ∼6–10%, which is considerably more accurate that the previously published data. Calculated detailed energy dependences are given of the neutron kerma factors for C, O, N, H, Si, and also for soft biological tissue and certain particle detectors. In conclusion, the authors wish to thank G.I. Britvich and I.A. Kurochkin for valuable discussions. Institute of High-Energy Physics, State Scientific Center, Russian Federation. Translated from Atomnaya énergiya, Vol. 80, No. 4, pp. 287–293, April, 1996.     

Equipment for fine crushing of ceramic materials (Review)

Efficient technological solutions and modern foreign and native milling equipment for ceramic materials are analyzed.Translated from Steklo i Keramika, No. 8, pp. 14–19, August, 1995.     

Structural analysis of permeable powder materials with random and matrix structures

We have theoretically analyzed permeable powder materials with bidisperse and biporous structures based on a conceptual approach using the concept of the matricity of porous systems. Approximate formulas are obtained for the porosity, specific surface area, equivalent pore radius, monophase and interphase contact area. Using the percolation model, we estimate the matricity of powder materials and demonstrate the feasibility of structural analysis of various powder systems using such an estimate.Institute of Problems in Materials Science, National Academy of Sciences of Ukraine, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 3–4, pp. 76–79, March–April, 1994.