ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12237.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Mortar bars reinforced by chopped steel wire and fiber glass were impregnated with methylmethacrylate which was then polymerized with benzoyl peroxide at 75°F. Monomer loading was 10 wt%, fibrous reinforcement 2 vol%. Tensile, compressive, and flexural strengths were measured for control specimens (without reinforcement and impregnation), reinforced specimens, impregnated specimens, and impregnated and reinforced specimens. Flexural strength was increased significantly by polymer impregnation (510% of control) and by fiber reinforcement (450% of control); the greatest increase was obtained with both polymer and steel fibers (2820% of control). This increase is probably caused by enhanced fiber‐paste bonding with polymer impregnati

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12238.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Distinct glass‐forming composition regions were found in the system Ge‐S (1) from GeS2to GeS9and (2) from GeS1.21a to GeS1.5The properties of these glasses, e.g. ir absorption spectra, thermal expansion, extraction of S8molecules with CS2, Vickers hardness, density, and optical absorption, led to the conclusion that the structures of glasses in the two regions differ. In region (1), the structure is based on a three‐dimensional inorganic polymer of polymeric S chains cross‐linked with Ge; in region (2), it involves GeS2(GeS4tetrahedra) and GeS (GeS6octahedra) components that can be regarded as network formers and modifiers, respe

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12239.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The contribution to the heat capacity of liquid Se, C̄p,r, arising from the ring‐polymer equilibrium was calculated from the equilibrium polymerization theory of Tobolsky and co‐workers. Above the polymerization transition temperature (∼360°K), C̄p,r∼(1/8)(ΘH32/RT2)(M/Mo), where ΘH3is the enthalpy change for the polymerization propagation step and (M/M0) is the monomer fraction of Se8rings. Below the transition temperature, C̄p,ris negligibly small. Heat capacities were measured for glassy and liquid Se from 180° to 280°K and from 320° to BOOK, respectively. Using available literature data and the equilibrium polymerization theory, the temperature dependence of the heat capacity of liquid Se was calculated; it agreed within experimental error with the measured temper

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12240.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The sintering and grain‐growth kinetics of finely divided MgAl2O4were determined from 1300° to 1600°C for densities up to 96% of theoretical. These results show that sintering is governed by volume diffusion and that the temperature dependence of the diffusivities is 157 exp [(‐118 kcal/mol)/RT] cm2/s. Grain growth follows the expression (G2‐G02)=Kt, whereK=51.3 exp [(‐110 kcal/mol)/

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12241.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The self‐diffusion of Ca in single‐crystal CaF2was determined by a tracer serial‐sectioning technique. From 987° to 1246°C, the results can be described byAnalyzing these results on the basis of a Ca ion vacancy diffusion mechanism, the enthalpy of migration, hm, can be estimated as 1.75 eV. The order of magnitude of the preexponential factor can be satisfactorily explained on the basis of lattice strain entropy

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12242.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Fiber formation and electrical conductivity were investigated in molybdenum phosphate glasses containing Ag2O; PdO was substituted for Ag2O and other constituents in the base glass. Temperature coefficients of electrical resistivity and linear expansion and other properties were determined for the bulk glasses. X‐ray diffraction confirmed that some compositions were amorphous; these glasses could be drawn by conventional methods into continuous filaments. Migration and reduction of Ag+at the glass fiber surfaces, induced by a secondary heat treatment, formed a metallic, electrically conducting, solder‐able surface film. Filament resistance of 0.07 Ω/ft/2000 fibers was achieved; resistance increased nearly linearly with temperature from −200° to 200°C. Imperfections in the metallic film, acting as flaw sites, contributed to a reduction of ∼50% in tensile strength compared to that of prist

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12243.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

For single‐crystal NiO‐CaO diffusion anneals in air at 1346° to 1527°C, the chemical interdiffusion coefficient increased exponentially with increasing Ni concentration; for NiO‐MgO at 1342° to 1346°C, a similar relation was found for [Ni]<0.41. The higher diffusivity and correspondingly greater flux in the NiO‐rich phase resulted in reaction at the interface and movement of the crystallographic boundary with the growth of the NiO at the expense of the other crystal. The crystallographic orientation of the volume swept out transformed to that of the grow

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12244.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The effect of α‐particle irradiation (5.5 MeV, total dose ∼1015particles/cm2) on the microstructure of ThO2was studied by transmission electron microscopy. The only as‐irradiated damage seen consisted of point defect agglomerations visible as small black spots. Subsequent heating to ∼1500°C in the electron microscope caused the spots to grow into loops 50 to 200 Å in diameter, but no voids, bubbles, or pores were observed. The preferred loop planes were {311}, {110}, and {012}, in that order of

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12245.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

With the aid of a technique which examines the transient drift in an applied field of electrons photoinjected into a single crystal specimen by a short pulse light, the electron mobility has been measured as a function of temperature in high‐resistivity, Na‐doped ZnO. The observed exponential temperature dependence of the mobility indicated that the drift mobility of electrons is controlled predominantly by thermal release from trapping states, of estimated density (5 to 22)×1015cm−2, lying in a 0.24‐eV region below the conduction band edge. Ohmic contacts of In used to inject electrons into a single‐crystal specimen of the same material produced space‐charge‐limited currents at high fields. The observed current‐voltage and current‐temperature characteristics indicated that either a discrete level or a narrow band of electron traps existed in the 0.6‐eV region below the conduction band edge with a d

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12246.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY