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PROPERTIES OF SOME VYCOR‐BRAND GLASSES *
Author(s) -
Nordberg Martin E.
Publication year - 1944
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1944.tb14473.x
Subject(s) - materials science , devitrification , borosilicate glass , softening point , porosity , composite material , glass melting , porous glass , leaching (pedology) , melting point , thermal expansion , opacity , thermal shock , mineralogy , chemical engineering , crystallization , optics , engineering , chemistry , environmental science , soil science , soil water , physics
A bstract Physical and chemical properties are discussed for Vycor‐brand 96% silica glasses prepared from glasses of lower silica content by a leaching process, and a brief résumé of this process is given. The intermediate porous glass and a translucent or white opaque form of the final 96% silica glass made by the Multiform process are briefly described. Ultraviolet and infrared transmission characteristics of glasses No. 790 and No. 791 are given. Summary Vycor‐brand glass No. 790 containing 96% silica is produced without the use of excessive melting temperatures by a process in which a relatively soft borosilicate glass is melted and shaped, the fluxes are removed by leaching, and the residual porous high‐silica structure is consolidated by heating. The outstanding properties of this glass are its very low coefficient of expansion and correspondingly high resistance to heat shock, its high softening point, low power factor, and high chemical durability, which make it useful for varied applications in the industrial and electrical fields as well as in the laboratory. The glass can be used continuously at temperatures up to 900°C. or for limited service at much higher temperatures provided it is not in contact with materials which react with or cause devitrification of silica. It can be lamp worked by methods similar to those used for fused silica. Porous glass is formed as an intermediate product in the process. It is characterized by pores of very small and relatively uniform radius, the average of which is in the order of 20 a.u. A translucent or opaque white glass is made by the Multiform process, which enables the production of massive ware and a variety of shapes that cannot be made directly in the clear form. Aside from transparency, the properties in general are the same as those of the clear glass. Vycor‐brand glass No. 791 is highly transparent to ultraviolet light at wave lengths down to 254 mμ or less, and glasses have been made with an appreciable transmission even at 185 mμ. Glasses No. 790 and No. 991 are highly transparent to the near infrared.