摘要:

AbstractThe effect of systematic variations in atmosphere between 100% oxidizing and 100% neutral was noted. The principles and definitions of color designation are given and possible physicochemical changes which result in color variation are considered. Experimental data indicate the relative stability of typical colors under atmospheric variations.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1944.tb14886.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

AbstractThe dielectric properties of ceramics depend on composition, density, and surface conditions as well as many other factors. Humidity influences the dielectric properties to a large extent. These studies show that the amount of moisture depends on the compacting pressure and that the firing temperature has some influence on the dielectric properties in connection with relative humidity. Frequency and air pressure have an entirely different influence on the dielectric properties in relation to relative humidity.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1944.tb14887.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

AbstractReports have indicated that calcined topaz might be useful as substitute material for Indian kyanite in high aluminous, mullite‐type refractories. Tests were conducted to determine the value of calcining and defluorinating raw topaz. Fifteen tons of minus 1‐in. topaz ore were calcined in a 25‐ft. rotary kiln of 20‐in. in inside diameter, at 2600° to 2950°C., with feed rate of 200 to 400 1b. per hour and feed retention in the kiln of 70 to 120 minutes. The best operating conditions were found to be 2700°F. and a feed rate of 300 1b. per hour at 0.90 r.p.m. of kiln rotation. The average fluorine content was 0.24% and the apparent porosity was 19%. A dust loss of 11% occurred during calcination, but no serious reduction in particle size occurred from the heat‐treatment. It seems to be practicable, therefore, to calcine and defluorinate raw topaz in a rotary kiln and to obtain a product suitable for the manufacture of mullite‐typ

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1944.tb14888.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

AbstractFactors have been derived for the calculation of the surface tensions of glasses from their compositions at temperatures of 1200° and 1400°C. The nine oxides evaluated are those commonly found in significant amounts in glass compositions. The surface tension of a glass may be calculated with a fair degree of assurance from its composition to within about 4 dynes per c

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1944.tb14889.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

AbstractThe glass used in the manufacture of lenses must be chemically stable and substantially free from bubbles, color, and striae. The lens designer is then concerned only with the refractive index and the dispersive power of the available glasses. Because practically every new lens must be achromatic, the positive elements used in it must be made from glass having a low dispersive power; the negative elements must have a relatively high dispersive power. The choice of refractive index is determined by many conflicting factors because the only “tools” available to the designer for the correction of many different aberrations are the radii of curvature of the lens surfaces, the thicknesses and air spaces, and the refractive indices of the glasses. The range of optical glasses commercially available and the reasons underlying the designer's selection of glass for different kinds of lenses are discus

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1944.tb14890.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY