ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11868.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Solid solution was observed in the system Na1‐xSrNCdPNbO3where N + P = x/2 between ≤ x 0.40 when the ratio of N:P was within the limits 1:2 → 2:1. Solid solution was observed at N:P ratios outside these limits but these materials were not studied extensively. A ferroelectric pseudomonoclinic perovskite phase was observed at 25° C when ≤ x≤ 0.10 in the compositional series studied. At higher values of x a ferroelectric pseudotetragonal phase with c/a 1 appeared between the pseudomonoclinic ferroelectric phase and the para‐electric pseudocubic phase which was stable at high temperatures. The pseudotetragonal phase, which exhibited much larger values of €/€0than the pseudomonoclinic phase, had a large peak in the electrical permittivity when it transformed to the pseudocubic state. The high‐temperature phase observed in these materials became a small‐cell perovskite structure when the subcell edge length attained 3.942 ± 0.002 A as a result o

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11869.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The hemispherical spectral emittances for the sesquioxides of yttrium, samarium, gadolinium, erbium, thulium, and ytterbium are given for five wavelengths in the visible portion of the spectrum over the range of 1400° to 3000°K. A reflectance technique incorporating a carbon arc image furnace and a standard of reflectance was used in the determinations. The emittance of zirconium dioxide was measured to check the validity of the metho

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11870.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The Young's modulus and internal friction of hyperstoichiometric uranium oxide at room temperature were determined by a sonic technique. Young's modulus decreased, whereas internal friction increased, with increasing O/U ratios. These effects are attributed to the precipitation of U4O9. A complete microstructural characterization is needed.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11871.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

A detailed study of the system Pb0–B203–Si02was undertaken because of the interest in lead borosilicate fluxes and the possibility of producing opaque low‐melting enamels by controlled liquid‐phase separations. Studies in the portion of the system containing greater than 60% PbO produced little change from previous work. The shape of the liquidus surface beneath the two‐liquid region and the shape of the immiscibility dome were determined. Much of the observed immiscibility is metastable, particularly for compositions containing greater than 40% SiO2. Using the electron microscope provided information on the way the rate of formation, stability, and texture of the immiscible liquids are affected by composition, time, and temperature. Finally, a high‐temperature centrifuge was constructed to separate the immiscible liquids and thus define tie lines within the immisci

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11872.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Relative energies of symmetrical [001] tilt boundaries in nickel oxide bicrystals were determined from the dihedral angle at the groove root with a surface profilometer. At 1535°C in air, the relative grain boundary energy increases with tilt angle up to about 20 degrees and then remains relatively constant with increasing angle. A strong temperature dependence of boundary energy is explained by segregation of point defects to the boundary. Grooving kinetics are controlled by volume diffusion of nickel, and a theoretical discussion of mass transport in nonstoichio‐metric solids is given, predicting this behavior under certain conditio

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11873.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The Dorn method, most commonly used to measure the activation energy of creep, was used to study the initial stage of sintering uranium dioxide in hydrogen from 700° to 850°C. The activation energy was approximately 100 kcal/mole. This result agrees with the value determined from analysis of isothermal shrinkage curves in the same temperature interva

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11874.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Direct reaction of liquid vanadium and graphite resulted in the carbon‐diffusion‐controlled formation of V2C (below approximately 2160°C) and VC scales below 2670° C. Parabolic growth behavior for both phases was observed; the growth constant for VC was expressible as K, V”= 2.13 exp ‐ (67,000/RT) cm2/sec. The growth rate of V2C was lower at 2000” than at 1900°C. The chemical diffusivity of carbon in VC above 2160°C was estimated to be Dcv”= 0.26 exp ‐ (58,300/RT) cm2/sec. Several contributions to the vanadium‐carbon binary diagram are presented. The VC + C = liquid eutectic point was determined to be at C/V = 1.15 ±

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11875.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

The composition (0.65Zn,0.35Mg)2SiO1was investigated. Its thermal expansion was 32 × 10‐7/°C from room temperature to 1000°C. Modulus of rupture was approximately 7000 psi between room temperature and 800°C, whereas Young's modulus held at approximately 11 × 10° psi over the same range. The substitution of 0.35 m oles Mg++for Zn++in Zn2Si04causes little change in many of the physical properties, but the solid solution sinters much more readily than pure Zn2Sio4. The willemite solid solution studied has very good thermal shock resistance between room temperature and

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11876.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1968.tb11877.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY