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186. Reaction brazing of polycrystalline graphites by high-melting solders
ABSTRACTS
697
186. Reaction brazing of polycrystalline graphites by high-melting solders F. Demuth and E. Fitzer (Znstitiitfiir Ckemische Tech&, Universitat KarLwuhe, W. Germany). High-melting solders are developed for the bra&g of graphite. As adhesive layer between the carbon andthe solder carbides of refractory metals Ti, Zr and Nb are formed by the diffusion of carbon through these layers. The carbide-forming component is used as an alloy with Ni, Al and Ge. As a result, the measured tensile strength of brazed graphite bodies is in the range of that of the used carbon artifacts. 187. A computerized carbon literature retrieval system F. J. Vastola, G. Johnson and P. L. Walker, Jr. ~Re~~~~ of Material Stdances and Materials Research L~or~o~, The Pen~~lvania State U~~v~sit~, U~~v~si~ Park, Pen~~~a~~a). A data base of over 35,000 references in the area of carbon has been assembled. Each reference has been coded with a series of keywords selected from a controlled vocabulary list. A literature retrieval system utilizing a minicomputer is described and examples of system operation are given. 188. The development of thermal shock resistant graphite* C. R. Kennedy and W. P. Eatherly (Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee). By careful pretreatment of green cokes, it has been found possible to more nearly match the shrinkage properties of filler and binder during heat-treatment to produce artificial graphite bodies. This process has yielded materials which, on the basis of limited test data, appear to have significantly improved thermal shock resistance. The process is currently being scaled up to produce usable sizes for more extensive testing. *Research supported by the Naval Ordnance Laboratory under contract with Union Carbide Corporation. 189. Chemical aspects of carbon brush wear D. W. McKee (Corporate Research and Development, General Electric Company, Schnectady, New York) and G. Gunnoe (Carbon Products Dept., General Electric Company, Stroudsburg, Pennsylvcania). Chemical factors may affect the life of carbon brushes in motors and generators. Metal impurities from the slip ring or commutator can act as catalysts for brush oxidation, leading to enhanced gasification rates, increased porosity and weakening of the brush structure. Chemical erosion of the brush is also promoted by arcing. 190. A method for predicting the longitudinal temperature distribution and heat transfer rate at the exit end of high-temperature continuous graphite furnaces R. F. Markel (R. F. Markel &3Associates, Inc. Consulting Engineers, Greenville, S.C.). Simplified expressions for the temperature distribution in the high-temperature zone and cooling zero were obtained by solving the basic differential equation for heat transfer, and were used to calculate the exit end passageway dimensions and heat losses for typical continuous ~aphitizing furnaces.
697
186. Reaction brazing of polycrystalline graphites by high-melting solders F. Demuth and E. Fitzer (Znstitiitfiir Ckemische Tech&, Universitat KarLwuhe, W. Germany). High-melting solders are developed for the bra&g of graphite. As adhesive layer between the carbon andthe solder carbides of refractory metals Ti, Zr and Nb are formed by the diffusion of carbon through these layers. The carbide-forming component is used as an alloy with Ni, Al and Ge. As a result, the measured tensile strength of brazed graphite bodies is in the range of that of the used carbon artifacts. 187. A computerized carbon literature retrieval system F. J. Vastola, G. Johnson and P. L. Walker, Jr. ~Re~~~~ of Material Stdances and Materials Research L~or~o~, The Pen~~lvania State U~~v~sit~, U~~v~si~ Park, Pen~~~a~~a). A data base of over 35,000 references in the area of carbon has been assembled. Each reference has been coded with a series of keywords selected from a controlled vocabulary list. A literature retrieval system utilizing a minicomputer is described and examples of system operation are given. 188. The development of thermal shock resistant graphite* C. R. Kennedy and W. P. Eatherly (Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee). By careful pretreatment of green cokes, it has been found possible to more nearly match the shrinkage properties of filler and binder during heat-treatment to produce artificial graphite bodies. This process has yielded materials which, on the basis of limited test data, appear to have significantly improved thermal shock resistance. The process is currently being scaled up to produce usable sizes for more extensive testing. *Research supported by the Naval Ordnance Laboratory under contract with Union Carbide Corporation. 189. Chemical aspects of carbon brush wear D. W. McKee (Corporate Research and Development, General Electric Company, Schnectady, New York) and G. Gunnoe (Carbon Products Dept., General Electric Company, Stroudsburg, Pennsylvcania). Chemical factors may affect the life of carbon brushes in motors and generators. Metal impurities from the slip ring or commutator can act as catalysts for brush oxidation, leading to enhanced gasification rates, increased porosity and weakening of the brush structure. Chemical erosion of the brush is also promoted by arcing. 190. A method for predicting the longitudinal temperature distribution and heat transfer rate at the exit end of high-temperature continuous graphite furnaces R. F. Markel (R. F. Markel &3Associates, Inc. Consulting Engineers, Greenville, S.C.). Simplified expressions for the temperature distribution in the high-temperature zone and cooling zero were obtained by solving the basic differential equation for heat transfer, and were used to calculate the exit end passageway dimensions and heat losses for typical continuous ~aphitizing furnaces.