ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12950.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

Pertinent works of previous investigators are reviewed briefly. A superior technique for the preparation of experimental glasses of high purity and chemical homogeneity is presented. Devitrification growth‐rate data and traction‐viscosity data are reported for high‐silica glasses of the system Al2O3‐SiO2. Glasses with added Al2O3were found to devitrify to cristobalite more rapidly than ultrapure silica glasses at a given temperature, and yet their fluidities (i.e., reciprocal viscosities) were found to be less. The devitrification growth rate, g, was found to be of zero order and to follow the temperature dependence In(g/T) =‐(B/T)+ InAover the temperature range 1561

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12951.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

Apparatus for measuring the rate of shrinking of a bubble of gas in a small cylinder of molten glass is described with the results of experiments with oxygen in No. 9010 glass at temperatures from 1000° to 1300°C. Approximate solutions of the Stefan problem, resulting from the application of Fick's law to these experiments, are given. They predict that in the initial stages, the rate of decrease in diameter of a bubble should be proportional to the square root of the time elapsed from the beginning of the experiment and be independent of the initial diameter of the bubble. The experiments show an acceleration of the initial rate not predicted by the approximate solutions. Increasing the temperature increases the rate of shrinking of the bubbles. In all experiments, when the bubble was followed for a sufficient length of time, an end point was reached at which the shrinking virtually stopped and a residual bubble remained indicating the presence of 1 or 2%, of impurity in the oxyge

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12952.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

A theoretical study of the possible mechanisms involved in the elastic deformation of a silicate glass indicates that if the only work done when such a glass is deformed is in the stretching or compressing of the Si‐O‐Si links, Poisson's ratio should be 0.25. Values less than this can be explained when the energy of deformation of the SiO4tetrahedra is considered and values greater than 0.25 if one takes into account the work done in deforming large modifying ions which fill the interstices in which they are loca

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12953.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

The dielectric properties, lattice parameters, and X‐ray and neutron diffraction intensities of solid solutions of BaTiO3containing Nb or Ta were studied. These solid solutions have a perovskite‐type structure with part of the Ti4+ions replaced by Nb5+or Ta6+ions and with some cation vacancies. These solid solutions exhibit a remarkable lowering of the Curie point, but the tetragonal‐orthorhombic and the orthorhombic‐rhombohedral transition points are

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12954.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

A variation of technique and thermal‐gradient apparatus from that previously used has been devised for quenching samples. This consists of a modified furnace and a roller and crimping machine. These modifications provide a higher maximum temperature of operation, a more satisfactory method of loading sample tubes, and a more efficient method of measuring temperature than previously use

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12955.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

Data on compatibility triangles and liquid immiscibility are presented for the portion of the ternary system bounded by SiO2, Li2O, SiO2, Li0O TiO2, and TiO2. X‐ray data showed the ternary compound Li2O. TiO2. SiO2to be tetragonal witha= 6.41 a.u. andC= 4.40 a.u. The compound is uniaxial negative with 1.81<<1.82 and 1.83<<1.84. It melted to two liquids at 1207° 3°C. Seven joins were established by solid‐state, fusion, and quenching methods. Using electron microscopy and petrographic microscope and quenching data, liquid immiscibility originating in the binary system SiO2‐TiO2was shown to extend over a substantial portion of the ternary

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12956.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

The solid phases formed at 1400°C. in air in the three‐component systems BaO‐SrO‐TiO2, BaO‐CaO‐TiO2, and SrO‐CaO‐TiO2are described. Besides solid solutions of components with known structures, some new ternary compounds have been studied. The dielectric constants and loss factors of a number of specimens are given. Crystallographic data of the compounds BaCaTiO4, Ba3Ca2Ti2O9, and Ca3Ti2O7and of the solid solution series (Ba, Sr), TiO4are presented. The preparation of the new compounds is descr

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12957.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

Thermal‐expansion data on Al2O3, BeO, MgO, B4C, SiC, and TiC were obtained to the temperatures where permanent deformation begins, due to sintering or other causes. The thermal expansion for these materials was found to be approximately linear over the measured temperature range. But as a linear extrapolation to room temperature was not possible, the coefficient of thermal expansion is not a constant over this temperature range. The results are compared with the latest published data for each material. The average coefficients of linear thermal expansion are given as follows:All BeO specimens which were heated to above 2050°C. had a very large expansion. Visual examination of the cooled specimens revealed that they had bent and cracked, the physical dimensions had enlarged, and the color had changed to a bright milky white. A brief discussion of the probable reasons for these changes is given. In the attempt to extend the expansion measurements, the melting point of BeO was obtained. A specimen of hot‐pressed BeO melted at 2450°± 30°C., whereas a slip‐cast BeO specimen melted at 247

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12958.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

A critical examination reveals certain weaknesses in the paper under discussion. New experimental evidence is presented which qualitatively confirms the conclusion of Newkirk and Sisler that large residual stresses may be present in cermets, but the magnitude of the stresses found is less than that previously reported.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb12959.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY