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ASTM F140-98(R2020) pdf free download

ASTM F140-98(R2020) pdf free download.Standard Practice for Making Reference Glass-Metal Butt Seals and Testing for Expansion Characteristics by Polarimetric Methods
1. Scope
1.1 This practice covers the preparation and testing of reference glass-metal butt seals of two general configurations, one applicable to determining stress in the glass and the other applicable to determining the degree of mismatch of thermal expansion (or contraction). Tests are in accordance with Test Method F218, Subsection 1.1. 1.2 This practice applies to all glass and metal (or alloy) combinations normally sealed together in the production of electronic components. It should not be attempted with glass- metal combinations having widely divergent thermal expan- sion (or contraction) properties. 1.3 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Summary of Practice
3.1 Five seals of a standard configuration are prepared from representative specimens of the glass and metal to be tested. The glass and metal are cleaned, treated, and sized to specified proportions. Plane-interfaced seals are formed, annealed, and measured for residual optical retardation. The stress parallel to the interface in each seal is calculated from the optical retardation, and the average stress is computed for the sample. For disk-seals the thermal expansion mismatch is calculated.
4. Significance and Use
4.1 The term “reference” as employed in this practice implies that either the glass or the metal of the reference glass-metal seal will be a “standard reference material” such as those supplied for other physical tests by the National Institute for Standards and Technology (NIST), or a secondary reference material whose sealing characteristics have been determined by seals to a standard reference material (see NIST SP 260). Until standard reference materials for seals are established by the NIST, secondary reference materials may be agreed upon between manufacturer and purchaser.
5. Apparatus
5.1 Polarimeter, as specified in Test Method F218 for measuring optical retardation and analyzing stress in glass. 5.2 Cut-offSaw, with diamond-impregnated wheel and No. 180 grit abrasive blade under flowing coolant for cutting and fine-grinding glass rod. 5.3 Glass Polisher, buffing wheel with cerium oxide polish- ing powder or laboratory-type equipment with fine-grinding and polishing laps. 5.4 Heat-treating and Oxidizing Furnaces, with suitable controls and with provisions for appropriate atmospheres (see Annex A1) for preconditioning metal, if required.5.5 Sealing Furnace, radiant tube, muffle or r-f induction with suitable controls and provision for use with inert atmo- sphere. 5.6 Annealing Furnace, with capability of controlled cool- ing. 5.7 Ultrasonic Cleaner, optional. 5.8 Fixture for Furnace Sealing, designed as suggested in Annex A2. 5.9 Micrometer Caliper, with index permitting direct read- ing accuracy of 0.02 cm. 5.10 Immersion Mercury Thermometer.
6. Materials
6.1 Metal—Representative specimen pairs ofthe metal from either rod or plate stock with dimensions satisfying the requirements of 7.2 or 7.3. The surfaces to be sealed should be relatively free of scratches, machine marks, pits, or inclusions that would induce localized stresses. The sealing surfaces should terminate in sharp edges at the peripheral corners to act as a glass stop. Edges that are rounded, such as appear on tumbled parts, will have the tendency to permit glass overflow. 6.2 Glass—Representative specimens of rod or plate glass, cut with either diamond-impregnated or other abrasive cutting wheels under flowing water. Dimensions (volume) shall satisfy the requirements of 7.2 or 7.3.
7. Test Specimen
7.1 Two basic cylindrical geometries are considered. For determining only the stress in glass, a seal whose total length is at least twice its diameter must be used. For determining expansion mismatch (as well as stress) a seal whose total thickness is equal to or less than one fifth of its diameter must be used. 7.2 The design for measuring stress provides seals between a cylindrical rod specimen of glass and metal of either rod or sheet (strip) form. The standard rod seal of Fig. 1(a) shall be made from specimens so that the diameter of the metal, d m , is 0.5 to 1.0 mm larger than the diameter of the glass, d g , before the seal is made; the lengths l g and l m shall each be at least d g . The standard sheet seal of Fig. 2(a) shall be made from specimens so that l g is at least 10 l m and a and b each exceed d g by at least 1.0 mm. In all cases d g shall be at least 5.0 mm; d is defined as the sighting line (or light path) through the glass at the interface after sealing.

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