ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14040.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

It was found that plastic deformation takes place in periclase above 1100°C., in rutile above 600°C., and in sapphire above 900°C. The mechanism is slip; in sapphire (0001) is the slip plane and [1120] is the slip directiog. All creep curves for sapphire in tension show the same qualitative features. Each consists of three stages: a stage of increasing creep rate (sometimes called an incubation period), a stage of large but decreasing creep rate (sometimes called first‐stage creep), and a stage of small and nearly constant creep rate (sometimes called second‐stage creep). The so‐called third‐stage creep, characteristic of metal behavior, has not been noted. Plastic deformation increases the electrical resistivity of sapphire at constant t

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14041.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

Additional information on phase equilibria in the subsolidus region of the system LiF‐BeF2was obtained and a study was made of the system PbF2–BeF2. In the system LiF‐BeF2the compound LiBeF3occurs; it decomposes below the solidus at 300° C. to yield Li2BeF4and the quartz form of BeF2. An additional subsolidus compound having the probable composition LiBe2F5forms below 275°C. No evidence was found for the existence of the alleged compound LiBe2F5. In the system PbF2‐BeF2two compounds occur: 3PbF2.BeF2and PbF2‐BeF2; the former melts congruently at 482°± 5°C. and the latter at 585°± 5°C. Extensive solid solution exists between PbF2.BeF2and BeF2. The cristobalite form of BeF2crystallizes from glasses of high BeF2content at temperatures of 450°C. or lower but is converted to the quartz form by heating at higher temperatures or in the

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14042.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The alkali elements in a wide range of glass and feldspar ore compositions can be rapidly determined with the flame spectrophotometer without making chemical separations. Flame photometer response to lithium, sodium, and potassium seems little affected by the presence of many of the glass constituents in concentration ranges commonly found in commercial glasses. The mean deviation in absolute per cent between chemical and flame photometer analyses for a series of twenty‐nine glass and ore samples is approximately 0.15% for each of the three common alkalis lithium, sodium, and potassium. Evaluation of the rubidium and cesium results was not possible since chemical analyses for these elements were not availabl

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14043.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

In conjunction with studies of the suitability of liquid metals for high‐temperature heat‐transfer systems, an investigation was made to determine the resistance of forty materials–eighteen ceramics and cermets, thirteen refractory metals, and nine high‐temperature alloys–to attack by Pb‐Bi eutectic alloy (44.5% Pb and 55.5% Bi) in a dynamic system at temperatures of 1500° or 2000°F. The experimental apparatus and procedure is described. With the exception of ZrC all the ceramics and cermets were resistant to attack by molten Pb‐Bi eutectic at 2000°F. Of the thirteen refractory metals only arc‐cast molybdenum exhibited resistance to Pb‐Bi at 2000°F. All nine of the high‐temperature alloys had po

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14044.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The dielectric properties of hot‐pressed synthetic mica were studied in comparison with those of other ceramic insulating materials with special attention to the variation of these properties with temperatures up to 400° C. Power‐factor and dielectric‐constant measurements were made at 1 mc., and the volume resistivity was determined on a d.‐c. resistance bridge with a voltage of 22.5. The comparison revealed the importance of evaluating the electrical properties of a dielectric material at the temperature at which the insulator is expected to operate. A plot of the power‐factor data against the reciprocal of the absolute temperature did not permit the results to be represonted by two intersecting straight lines, as has been previousl

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14045.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY

摘要:

The shrinkage characteristics of forty‐three commercial high‐calcium limestones, calcined at four different temperatures above the dissociation temperature, were studied by means of bulk‐density measurements of the stones and their respective calcines. Chemical, spectrographic, and petrographic analyses could not be correlated with the shrinkag

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1954.tb14046.x

出版商:Blackwell Publishing Ltd    

年代:1954

数据来源: WILEY