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A Method for Measuring the Flow Point of Glass
Author(s) -
LILLIE HOWARD R.
Publication year - 1952
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.1151-2916.1952.tb13089.x
Subject(s) - softening point , materials science , glass fiber , composite material , melting point , thermodynamics , mineralogy , optics , mechanics , chemistry , physics
The need for a new reference point for glasses, at a temperature substantially above the softening point, is discussed from the standpoint of development of. new glasses, control of properties, and behavior in applications where reworking is required. An apparatus and a procedure are described by which a fiber elongation test indicates the “flow point,” or temperature at which a glass reaches a viscosity of 10 5 poises. A short section of a glass fiber, nominally 0.65 mm. in diameter, is heated under specified conditions of load and heat application. The heating time required for the fiber to draw down to a thread indicates the temperature attained. When properly standardized with one or more known glasses, the precision is equivalent to from 1°C. for soft glasses to 5°C. for hard glasses. The effect of infrared absorption by the sample is examined, and a correction curve is given for use when such absorption is abnormally great.