ASTM F44-95(2006)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F44 – 95 (Reapproved 2006)
Standard Specification for
Metallized Surfaces on Ceramic
This standard is issued under the fixed designation F44; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Ordering Information
1.1 This specification covers requirements for powdered 4.1 The manufacturer and purchaser shall agree upon spe-
refractory metal coatings produced with or without additives. cific quality levels as outlined in the following sections:
These coatings are applied to ceramic bodies in order to join 4.1.1 Uniformity of metallizing (Section 5),
ceramic bodies to metals or to other metallized ceramics by 4.1.2 Thickness of metallizing (Section 6),
meansofbrazingorsoldering.Includedinthisspecificationare 4.1.3 Secondary metal layer on the metallizing (Section 9),
requirements for a secondary metallic layer which is usually 4.1.4 Values for bond strength (Section 10), and
applied over the refractory metal layer. 4.1.5 Vacuum tightness of brazed metallized ceramic as-
1.2 The values stated in inch-pound units are to be regarded semblies (dependent on allowable use of manufacturer’s prod-
as the standard. The values given in parentheses are for uct) (Section 11).
information only.
5. Uniformity of Metallizing
2. Referenced Documents
5.1 Either of the following two levels of quality may be
2.1 ASTM Standards: agreed upon between manufacturer and purchaser, depending
E3 Guide for Preparation of Metallographic Specimens upon end use, seal area, and geometry.
F19 Test Method for Tension and Vacuum Testing Metal- 5.2 Level A—Less Demanding Application:
lized Ceramic Seals 5.2.1 Thin areas where the ceramic substrate can usually be
seen without magnification through the metallizing will be
3. Terminology
acceptable only if all of the following conditions are met:
3.1 Definitions of Terms Specific to This Standard:
5.2.1.1 There are no more than two such areas on any one
3.1.1 ceramics—as referred to in this specification are coated band, spot, or pattern detail.
understood to be inorganic, nonmetallic materials, the major 5.2.1.2 Their extremities are no closer than 10 % of the total
phase of which must be crystalline. A glassy intercrystalline
band length to each other.
matrix may be present as one of the minor phases. 5.2.1.3 They are no wider than 10 % of the width of the
3.1.2 metallizing— on a ceramic, is a process whereby a
band but not exceeding 1 mm.
sinteredmatrixofmetalparticlesfirmlyadherestotheceramic. 5.2.1.4 Theircumulativelengthdoesnotexceed25 %ofthe
3.1.3 refractory metals—those metals with melting points
total band length.
equal to or higher than that of chromium.Therefore, this group 5.2.2 Defects such as brush marks, screen marks, marks in
includes chromium, columbium, molybdenum, rhenium, tanta-
themetallizingleftbyforeignmattersuchaslint,dust,etc.,and
lum, and tungsten. pits or blisters, will be acceptable if they meet the four
conditions outlined in 5.2.1.1 through 5.2.1.4. Such defects
will also be acceptable if their raised edges do not interfere
This specification is under the jurisdiction of ASTM Committee F1 on
with proper assembly of the joint.
Electronics and is the direct responsibility of Subcommittee F01.03 on Metallic
5.2.3 Projections on metallized surfaces, such as oversized
Materials.
particles or agglomerates will be objectionable if they interfere
Current edition approved Jan. 1, 2006. Published January 2006. Originally
with assembly.
approved in 1968. Last previous edition approved in 2000 as F44-95 (2000). DOI:
10.1520/F0044-95R06.
5.2.4 Continuous coatings over sharp edges or corners with
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
a radius less than ⁄32 in. (0.8 mm) will not be required unless
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
by specific agreement between manufacturer and purchaser.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 5.3 Level B—Demanding Application:
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F44 – 95 (2006)
5.3.1 Thin areas will be unacceptable where the ceramic 9.3 The purchaser shall specify the metal to be applied.
substrate can be seen through the metallizing when examined 9.4 Manufacturer and purchaser shall agree upon the layer
at 403 magnification. thickness, including maximum and minimum thickness limits.
5.3.2 Defects through which the underlying ceramic can be Measurement shall be by microscopical examination as de-
observed, such as brush or screen marks, marks left by foreign scribed in 6.1.
matter such as lint or dust, and pits or chips, will be acceptable 9.5 Brightness of clean matte deposits may not be specified.
only if all of the following conditions are met: 9.6 Oxide films on the secondary metallic layer will not be
5.3.2.1 There are no more than two such defects on any cause for rejection.
coated band, spot, or pattern detail.
9.7 Defectssuchasblistersdevelopedinsubsequentheating
5.3.2.2 Their extremities are not closer together than 10 % operations will be acceptable only in 5.2 Level A application
of the length of the metallized area in which they occur. and only if all the following conditions are met:
5.3.2.3 They are not wider than 5 % of the width of area nor 9.7.1 There are no more than two blisters on any one coated
longer than 2 % of the length of area.
band, spot, or pattern detail.
5.3.3 Continuous coatings over sharp corners with a radius 9.7.2 No blister is closer than 10 % of the total band length
less than ⁄32 in. (0.8 mm) will not be required so long as
to another blister.
subsequent plating covers the radius. The specific gap permis-
9.7.3 Maximum dimension of any blister does not exceed
sibleatsuchacornershallbeagreeduponbymanufacturerand
10 % of the width of the band; in any case not to exceed ⁄32 in.
purchaser.
(0.8 mm).
5.3.4 Projections on metallized surfaces, such as oversize
9.8 The secondary metallic layer must adhere to the metal-
particles or agglomerates will be objectionable if they interfere
lizing underneath to the extent that no separation exists at this
with assembly or alignment.
interference in tension or torque peel tests after sintering of the
layer in a suitable protective atmosphere.
6. Thickness of Metalizing
9.9 Cleanliness such as absence of fingerprints, dirt, etc.,
6.1 Measure thickness by observation through a calibrated
which may interfere with brazing or soldering, is not a
micrometer eyepiece in a metallurgical microscope. Measure a
requirement for acceptance unless agreed upon between manu-
polished cross section that is perpendicular to the metallized
facturer and purchaser.
surface. The measurement shall consist of the average of at
9.10 When the secondary metallic layer is omitted from the
least three representative readings taken where the upper and
purchaser requirements, the following items shall become a
lower edges of the layer are parallel. Magnification must be at
part o
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