ASTM F44-95(2011)
(Specification)Standard Specification for Metallized Surfaces on Ceramic
Standard Specification for Metallized Surfaces on Ceramic
ABSTRACT
This specification covers requirements for powdered refractory metal coatings produced with or without additives. These coatings are applied to ceramic bodies in order to join ceramic bodies to metals or to other metallized ceramics by means of brazing or soldering. Included in this specification are requirements for a secondary metallic layer which is usually applied over the refractory metal layer. Two levels of quality for uniformity of metallizing are discussed, Level A and Level B. These levels discuss conditions and requirements needed in order to accept the uniformity of metallizing. Thickness of metallizing shall be measured using a metallurgical microscope. A polished cross-section that is perpendicular to the metallized surfaced is measured. The particles in the metallized layer must be sintered in order to form a dense matrix when viewed in cross section at 400 times. This cross section will indicate the extent of threedimensional sintering. A torque peel test and a tension test shall be performed in order to determine the bond strength of brazed metallized ceramics. Vacuum tightness of the brazed metallized ceramics shall also be determined.
SCOPE
1.1 This specification covers requirements for powdered refractory metal coatings produced with or without additives. These coatings are applied to ceramic bodies in order to join ceramic bodies to metals or to other metallized ceramics by means of brazing or soldering. Included in this specification are requirements for a secondary metallic layer which is usually applied over the refractory metal layer.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:F44 −95(Reapproved 2011)
Standard Specification for
Metallized Surfaces on Ceramic
ThisstandardisissuedunderthefixeddesignationF44;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope includes chromium, columbium, molybdenum, rhenium,
tantalum, and tungsten.
1.1 This specification covers requirements for powdered
refractory metal coatings produced with or without additives.
4. Ordering Information
These coatings are applied to ceramic bodies in order to join
ceramic bodies to metals or to other metallized ceramics by 4.1 The manufacturer and purchaser shall agree upon spe-
meansofbrazingorsoldering.Includedinthisspecificationare cific quality levels as outlined in the following sections:
4.1.1 Uniformity of metallizing (Section 5),
requirements for a secondary metallic layer which is usually
applied over the refractory metal layer. 4.1.2 Thickness of metallizing (Section 6),
4.1.3 Secondary metal layer on the metallizing (Section 9),
1.2 Thevaluesstatedininch-poundunitsaretoberegarded
4.1.4 Values for bond strength (Section 10), and
as standard. The values given in parentheses are mathematical
4.1.5 Vacuum tightness of brazed metallized ceramic as-
conversions to SI units that are provided for information only
semblies (dependent on allowable use of manufacturer’s prod-
and are not considered standard.
uct) (Section 11).
1.3 Thevaluesstatedininch-poundunitsaretoberegarded
as the standard. The values given in parentheses are for
5. Uniformity of Metallizing
information only.
5.1 Either of the following two levels of quality may be
agreed upon between manufacturer and purchaser, depending
2. Referenced Documents
upon end use, seal area, and geometry.
2.1 ASTM Standards:
5.2 Level A—Less Demanding Application:
E3Guide for Preparation of Metallographic Specimens
5.2.1 Thin areas where the ceramic substrate can usually be
F19Test Method for Tension and Vacuum Testing Metal-
seen without magnification through the metallizing will be
lized Ceramic Seals
acceptable only if all of the following conditions are met:
5.2.1.1 There are no more than two such areas on any one
3. Terminology
coated band, spot, or pattern detail.
3.1 Definitions of Terms Specific to This Standard:
5.2.1.2 Theirextremitiesarenocloserthan10%ofthetotal
3.1.1 ceramics—as referred to in this specification are
band length to each other.
understood to be inorganic, nonmetallic materials, the major
5.2.1.3 They are no wider than 10% of the width of the
phase of which must be crystalline. A glassy intercrystalline
band but not exceeding 1 mm.
matrix may be present as one of the minor phases.
5.2.1.4 Theircumulativelengthdoesnotexceed25%ofthe
3.1.2 metallizing— on a ceramic, is a process whereby a
total band length.
sinteredmatrixofmetalparticlesfirmlyadherestotheceramic. 5.2.2 Defects such as brush marks, screen marks, marks in
themetallizingleftbyforeignmattersuchaslint,dust,etc.,and
3.1.3 refractory metals—those metals with melting points
pits or blisters, will be acceptable if they meet the four
equaltoorhigherthanthatofchromium.Therefore,thisgroup
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
with proper assembly of the joint.
This specification is under the jurisdiction of ASTM Committee F01 on
5.2.3 Projections on metallized surfaces, such as oversized
Electronics and is the direct responsibility of Subcommittee F01.03 on Metallic
Materials.
particlesoragglomerateswillbeobjectionableiftheyinterfere
Current edition approved June 1, 2011. Published June 2011. Originally
with assembly.
approved in 1968. Last previous edition approved in 2006 as F44-95 (2006). DOI:
5.2.4 Continuous coatings over sharp edges or corners with
10.1520/F0044-95R11.
2 1
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:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F44−95(Reapproved 2011)
5.3.1 Thin areas will be unacceptable where the ceramic
substrate can be seen through the metallizing when examined
at 40× magnification.
F44−95 (2011)
5.3.2 Defects through which the underlying ceramic can be 9.4 Manufacturer and purchaser shall agree upon the layer
observed, such as brush or screen marks, marks left by foreign thickness, including maximum and minimum thickness limits.
mattersuchaslintordust,andpitsorchips,willbeacceptable Measurement shall be by microscopical examination as de-
only if all of the following conditions are met: scribed in 6.1.
5.3.2.1 There are no more than two such defects on any
9.5 Brightnessofcleanmattedepositsmaynotbespecified.
coated band, spot, or pattern detail.
9.6 Oxide films on the secondary metallic layer will not be
5.3.2.2 Their extremities are not closer together than 10%
cause for rejection.
of the length of the metallized area in which they occur.
9.7 Defectssuchasblistersdevelopedinsubsequentheating
5.3.2.3 Theyarenotwiderthan5%ofthewidthofareanor
operations will be acceptable only in 5.2 Level A application
longer than 2% of the length of area.
and only if all the following conditions are met:
5.3.3 Continuous coatings over sharp corners with a radius
9.7.1 Therearenomorethantwoblistersonanyonecoated
less than ⁄32 in. (0.8 mm) will not be required so long as
band, spot, or pattern detail.
subsequent plating covers the radius. The specific gap permis-
9.7.2 No blister is closer than 10% of the total band length
sibleatsuchacornershallbeagreeduponbymanufacturerand
to another blister.
purchaser.
5.3.4 Projections on metallized surfaces, such as oversize 9.7.3 Maximum dimension of any blister does not exceed
10%ofthewidthoftheband;inanycasenottoexceed ⁄32in.
particlesoragglomerateswillbeobjectionableiftheyinterfere
with assembly or alignment. (0.8 mm).
9.8 The secondary metallic layer must adhere to the metal-
6. Thickness of Metalizing
lizing underneath to the extent that no separation exists at this
6.1 Measure thickness by observation through a calibrated
interferenceintensionortorquepeeltestsaftersinteringofthe
micrometer eyepiece in a metallurgical microscope. Measure a
layer in a suitable protective atmosphere.
polished cross section that is perpendicular to the metallized
9.9 Cleanliness such as absence of fingerprints, dirt, etc.,
surface. The measurement shall consist of the average of at
which may interfere with brazing or soldering, is not a
least three representative readings taken where the upper and
requirementforacceptanceunlessagreeduponbetweenmanu-
lower edges of the layer are parallel. Magnification must be at
facturer and purchaser.
least 400× to obtain satisfactory accuracy.Asuggested method
9.10 When the secondary metallic layer is omitted from the
for specimen pre
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