ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15337.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The flame resistance of six refractories of commercial purity was measured in the well‐mixed stoichiometric portion and in the unmixed fluorine‐rich portion of a hydrogen‐fluorine diffusion flame. Graphite, silicon carbide, zircon, alumina, zirconia, and magnesia are decreasingly resistant to the test flame in the order indicated. The rate of ablation is about three times more rapid and the average surface temperatures are 130° to 745° C. higher where the flame is fluorine‐rich. Graphite and silicon carbide are suggested for use in HF flames because of their good thermal‐shock resistance and relative chemical inertness to the flame. Consideration of the ablation chemistry indicates that zircon dissociates and then, like graphite, silicon carbide, and zirconia, ablates by flame‐solid reaction, whereas alumina and magnesia form liquids which flow from the imp

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15338.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Some work is described that was carried out on the reactions which took place when uranium dioxide and graphite were heated together in an inert atmosphere at temperatures up to 2130°C. Rates of the reactions taking place at the interface between the two reactants were determined and were found to follow a parabolic rate equation

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15339.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The effect of changes in the glass structure on the colors and magnetic susceptibilities of iron was studied in glasses made of CaO, B2O3, and Al2O3(cabal glasses). As the number of gaps in the structure increased, an increase in the general absorption and a decrease in magnetic susceptibility was observed and was attributed to ferrous iron in network‐forming positions. Further increase in the number of gaps was accompanied by a general increase in transmission as well as by an increase in magnetic susceptibility. This was attributed to the loosening of the structure around the ferrous iron which could easily escape from the interstices and be oxidized to colorless ferric iron taking network‐forming positions. The intensity of the ferrous band depended on the concentration of the ferrous iron and also was affected by the polarizing power of the neighboring cati

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15340.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

A method is developed for determining crack velocities from the stress‐time curve of fracture. Velocities of glass broken in air and in vacuum converge at a value between 1 and 10 mm. per second. This convergence is considered to be the upper limit of the fatigue range. Fracture energy has been computed in terms of strain energy release rates. For glass broken in air under low stresses this energy is about equal to the surface energy of the glass, but when in vacuum it is fifteen times greater. At the upper limit of the fatigue range it is thirty times greater, whereas at the terminal velocity of fracture it is of the order of fifty times greater. It is concluded that surface energy must constitute only a small part of the energy absorbed in the fracture process. This excess energy has a pronounced influence on the fracture process and on the measured strength of glas

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15341.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

This study is an investigation of the infrared properties of SiO in the wave‐length range 1 to 30 μ‐ The samples used in this study consisted of the commercially available bulk silicon monox and thin films made by evaporating this bulk material. Films which were made by evaporating onto a silicon substrate were used for transmission measurements. Reflectivity measurements as well as transmission measurements were made with the bulk material. From the foregoing data it was concluded that, although the bulk material is not SiO but rather a stoichiometric mixture of Si and SiO2, the evaporated films are a true amorphous SiO p

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15342.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Observations of microstructure changes in several systems and the rate of densification during sintering of magnesium oxide, titanium carbide, and tungsten carbide in the presence of a liquid phase indicate that the densification rate is controlled by diffusion through a liquid film between particles. Dependence of the sintering rate on time, particle size, and temperature are in agreement with predictions. Theoretical estimations of the sintering rate are in reasonable agreement with experimental measurements.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15343.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The transformation of quartz to cristobalite was studied in the temperature range 1400° to 1650° C. The process which was believed to be a direct one was found to be a consecutive reaction involving an intermediate transition phase. Both Madagascar and Brazilian quartz were used to study the transformation reaction. The reaction rate was found to be much faster for the Madagascar quartz than for the Brazilian quartz, although no difference in their impurity content was found in the spectrographic analysis. An approximate consecutive reaction kinetics was applied and the deviation of the experimentally observed values of the transition phase at a particular temperature from that of the mathematical prediction was noted and is discusse

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15344.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Little exact information exists on the relation of mineralogical composition of clay materials to their properties after firing. Property‐composition diagrams are constructed for linear shrinkage and apparent porosity of quartz‐kaolinitemica mixtures fired at 1100° and 1200°C.; contours of equal shrinkage and equal porosity are derived. Sixty natural clays and shales are analyzed semiquantitatively for mineral content, and their shrinkage and porosity values are obtained after firing to 1100° and 1200°C. The ceramic properties of the natural materials are compared with those of the prepared mixtures. Conclusions are drawn regarding the influence of mineralogical composition on the ceramic properties. The mica content is shown to be particularly important because of its role in the for mation of a glassy co

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15345.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15346.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY