ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14427.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Tensile, creep, and modulus of elasticity data were determined for hot‐pressed zirconium carbide. The material was relatively impure, containing 1 to 2% nitrogen and 1 to 2% free carbon. Tension and creep properties, which were measured to 2600° C, indicated that above 2100°C the strength was 2000 psi or lower and the elongation was 40% or more, thus signifying little structural usefulness. It is proposed that the results were influenced by impurities at the grain boundaries. Room‐temperature modulus of elasticity values averaging 51.6 × 106psi were obtained by dynamic m

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14428.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

To supplement efforts to develop UN as a nuclear fuel material, a study of the phase relations in the system uranium‐nitrogen was conducted. The decomposition behavior and melting point of UN was studied in a controlled nitrogen‐pressure apparatus in which cast specimens of UN were heated and observed. UN decomposed at pressures of nitrogen below 2.5 atm at temperatures below 2850° C and melted congruently at 2850° C and pressures of 2.5 atm or greater. The nitrogen content of the liquid uranium phase in equilibrium with UN was determined by heating uranium in a UN crucible and then quenching and analyzing the equilibrated phase. The solubility of nitrogen in atomic percent can be expressed as S = 2.45 × 104exp (‐38,800/RT) for temperatures in OK. Studies in the region U2N3‐UN2of the system which were performed using a Sievert‐type apparatus showed that although these compounds are structurally dissimilar, they form a series of continuous solid solutions. Only UN2formed at high pressures and low temperatures. A pressure‐temperature schematic diagram and a temperature‐composition schematic diagram for a nitrogen pressure of 1 atm for the system uranium‐nitrogen are presented. At this pressure, UN decomposed at 2800° C and U2N3de

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14429.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The electrical conductivity of compositions in the system ZrO2‐CaZrO3was examined. The composition of maximum conductivity in this system is within the cubic solid‐solution region close to the low‐calcia cubic solid‐solution phase boundary. The conductivity decreases from the single‐phase cubic solid solution to both of the adjacent two‐phase regions; the decrease is more rapid on the ZrO2‐rich two‐phase side. This effect is discussed on the basis of differing

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14430.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

A square‐loop ferrite composition, Mg0.675Mn0.535–Fe1.8000O4, having high purity and fine particle size was prepared by pyrolysis of coprecipitated oxalates or hydrated oxides. The control of pH had a marked effect on the stoichiometry of the coprecipitated divalent oxalates, and ap optimum pH of 2.5 to 3.0 was observed. Thermal analysis was performed on the coprecipitated materials and on individual components; it revealed that the coprecipitated oxalates formed a solid solution whereas the hydrated oxides did

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14431.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Plastic‐deformation studies were made of cesium bromide which exhibits no cleavage planes. Single crystals were found to be “soft” and ductile if they were favorably oriented relative to the loading axis to activate the {110}∝001〈 slip systems. Kink bands were formed by applying a compressive load normal to a {100} plane. Cross slip was found to occur during deformation at all test temperatures. Tensile loads applied normal to {100} and {110} planes caused fracture along {110} planes, whereas compressive loads normal to {100} planes forced fracture along {112} planes. The ductility of polycrystalline cesium bromide was found to be limited because of the lack of five independent slip systems. The specimens with smaller grains showed less strain at fracture and greater strain hardening than the larger‐grained specimens. The mechanism fracture was intergranular u

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14432.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Phase equilibrium relations in the system Na2O‐GeO2have been determined using standard quenching techniques supplemented by differential thermal analysis. Two congruently melting compounds, Na2O·GeO2and 2Na2O·9GeO2, exist; the melting points are 1103°± 15°C and 1073°± 3°C, respectively. The eutectic temperature between GeO2and 2Na2O·9GeO2is 950°±f 10°C at 94.5 wt GeO2. The eutectic temperature between 2Na2O · 9GeO2and Na2O·GeO2is 790° f 10°C at about 75 wt% GeO2. Both the refractive index and the density of glasses in the system Na2O‐GeO2exhibit maximum values at about 16 to 18 mole % Na2O. The Ge‐O‐Ge absorption band at 890 cm−1shifts toward lower wave numbers

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14433.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The technical adiabatic elastic moduli E[hkl]and Ghklof single crystals of magnesium oxide were measured over the temperature range 298° to about 1600°K by a Förster‐type resonance method. These data were compared with the low‐temperature values (80° to 560°K) of the principal elastic constants cijand coefficients Sy reported by Durand. Combining Durand's data and the present data, the elastic moduli for single‐crystal magnesium oxide were evaluated for the temperature range 80° to 1600°K. Young's modulus and the shear modulus of densely formed isotropic polycrystalline magnesium oxide were measured over the temperature range 298° to 1600°K. The data on the elastic constants of the single crystals were compared with the measured elastic moduli of the isotropic polycrystalline magnesium oxide on the basis of the Voigt‐Reuss‐Hill approximation. The temperature dependence of the elastic moduli was fitted into the expression M = Mc— BT exp (—Tc/T) suggested by Wachtmanet al.; mean deviations were less than 0.4% for the temperature range considered. The significance of the present data is discussed with particular emphasis on the following points: (1) the temperature variation of the elastic modulus is a function of thermal expansion, (2) the temperature dependence of the elastic modulus can be well described by the foregoing expression for a wide range of temperature, (3) the expression gives a value of the elastic modulus at 0°K, and (4) it may be possible to make use of measurements on the elastic properties of a densely sintered polycrystalline material to obtain information heretofore obtainable only from the correspond

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14434.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Glasses corresponding to mole formulas R2TiO3and R2Ti2O5were prepared in 1‐ to 5‐g quantities by quenching in a platinum crucible. K2O, Rb2O, and Cs2O formed fairly stable glasses with TiO2. On heat treatment, these glasses nucleated readily and formed opal‐like glasses. Li2O and Na2O, however, did not form glasses with TiO2in 1‐g quantities. Hygroscopicity increased with the alkali content and decreased with the increase in TiO2concentration. The refractive indices of the glasses ranged from 1.66 to 1.90. These facts indicate that TiO2is a glass former in its own right and that Ti4+exists in sixfold coordination in these

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14435.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb14436.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY