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ASTM C829-81(2022)

Current Reaffirmation

Standard Practices for Measurement of Liquidus Temperature of Glass by the Gradient Furnace Method

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1.1 These practices cover procedures for determining the liquidus temperature (Note 1) of a glass (Note 1) by establishing the boundary temperature for the first crystalline compound, when the glass specimen is held at a specified temperature gradient over its entire length for a period of time necessary to obtain thermal equilibrium between the crystalline and glassy phases.

Note 1: These terms are defined in Terminology C162.

1.2 Two methods are included, differing in the type of sample, apparatus, procedure for positioning the sample, and measurement of temperature gradient in the furnace. Both methods have comparable precision. Method B is preferred for very fluid glasses because it minimizes thermal and mechanical mixing effects.

1.2.1 Method A employs a trough-type platinum container (tray) in which finely screened glass particles are fused into a thin lath configuration defined by the trough.

1.2.2 Method B employs a perforated platinum tray on which larger screened particles are positioned one per hole on the plate and are therefore melted separately from each other.2

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.


3.1 These practices are useful for determining the maximum temperature at which crystallization will form in a glass, and a minimum temperature at which a glass can be held, for extended periods of time, without crystal formation and growth.

SDO ASTM: ASTM International
Document Number C829
Publication Date Feb. 1, 2022
Language en - English
Page Count 9
Revision Level 81(2022)
Supercedes
Committee C14.04
Publish Date Document Id Type View
Feb. 1, 2022 C0829-81R22 Reaffirmation
May 1, 2015 C0829-81R15 Reaffirmation
April 1, 2010 C0829-81R10 Reaffirmation
Sept. 1, 2005 C0829-81R05 Reaffirmation
Jan. 1, 2000 C0829-81R00 Reaffirmation
Jan. 1, 2000 C0829-81R95E01 Reaffirmation