ASTM F1147-99
(Test Method)Standard Test Method for Tension Testing of Calcium Phosphate and Metal Coatings
Standard Test Method for Tension Testing of Calcium Phosphate and Metal Coatings
SCOPE
1.1 This test method covers tension testing of calcium phosphate and metallic porous coatings adhering to dense metal substrates at ambient temperatures. It assesses the degree of adhesion of coatings to substrates, or the internal cohesion of a coating in tension normal to the surface plane.
1.2 The values stated in inch-pound units are to be regarded as the standard.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:F1147–99
Standard Test Method for
Tension Testing of Calcium Phosphate and Metallic
Coatings
This standard is issued under the fixed designation F 1147; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope film form or bulk form, but it must have a minimum bulk
tensile strength of 34.5 MPa (5000 psi).
1.1 This test method covers tension testing of calcium
4.2 The tensile load must be applied normal to the plane of
phosphate and metallic porous coatings adhering to dense
the coating utilizing a tension machine which is capable of
metal substrates at ambient temperatures. It assesses the degree
determining the maximum strength of the coating or coating
of adhesion of coatings to substrates, or the internal cohesion
attachment to the substrate interface.
of a coating in tension normal to the surface plane.
1.2 The values stated in inch-pound units are to be regarded
5. Significance and Use
as the standard.
5.1 The tensile test method is recommended for tension
1.3 This standard does not purport to address all of the
testing of calcium phosphate/substrate or porous metal coating/
safety concerns, if any, associated with its use. It is the
substrate combinations and can provide information on the
responsibility of the user of this standard to establish appro-
adhesive or cohesive strength of coatings under (uniaxial)
priate safety and health practices and determine the applica-
tensile stress.
bility of regulatory limitations prior to use.
5.2 The test method may be useful for comparative evalu-
2. Referenced Documents ation of adhesive or cohesive strengths of a variety of types of
coatings. Coatings may be applied using a variety of methods,
2.1 ASTM Standards:
including but not limited to plasma-spraying and sintering.
C 633 Test Method for Adhesion or Cohesive Strength of
Information developed using this method may be useful for
Flame-Sprayed Coatings
3 certain quality control and design purposes.
E 4 Practices for Force Verification of Testing Machines
5.3 The test should not be considered to provide an intrinsic
E 6 Terminology Relating to Methods of Mechanical Test-
value for utilization directly in making calculations such as
ing
determining the ability of a coating to withstand specified
E 8 Test Methods forTensionTesting of Metallic Materials
environmental stresses.
3. Terminology
5.4 Processing variables such as substrate preparation prior
to coating, surface texture, coating technique variables or
3.1 The definitions of terms relating to tension testing
postcoating heat treatment variables may introduce a signifi-
appearing in Terminology E 6 shall be considered as applying
cant effect on the results of the tension test. The specimen
to the terms used in this test method.
being evaluated must be representative of the actual end use
4. Summary of Test Method
coating.
4.1 The tensile test method consists of subjecting a speci-
6. Apparatus
men assembly composed of one coated and one uncoated
6.1 Testing Machines—Machines used for testing shall
component to a tensile load. In the case of the calcium
conformtotherequirementsofPracticesE 4.Theloadsusedin
phosphate coatings, the components to be tested must be
determining tensile strength and yield strength shall be within
bonded together by use of a polymeric adhesive. In the case of
the loading range of the testing machine as defined in Practices
the metallic coatings, the components may either be bonded
E4.
with the adhesive, or sintered together.The adhesive may be in
6.2 Gripping Devices:
6.2.1 General—Various types of grips may be used to
This test method is under the jurisdiction ofASTM Committee F04 on Medical
transmit the load applied to the specimens by the testing
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
machine. To ensure axial tensile stress, it is important that the
F04.15 on Materials Test Methods.
specimen axis coincide with the centerline of the heads of the
Current edition approved March 10, 1999. Published June 1999. Originally
published as F 1147 – 88. Last previous edition F 1147 – 95. testingmachineandthatthecoatingtestplanebeperpendicular
Annual Book of ASTM Standards, Vol 02.05.
Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1147–99
to the axial load.Any departure from this requirement (that is, material other than FM 1000 is used, or the condition of the
any eccentric loading) will introduce bending stresses that are FM 1000 is unknown, it must be tested to establish its
not included in the usual stress calculation (force/cross- equivalence fresh FM 1000. Testing should be performed
sectional area). without the presence of the coating to establish the perfor-
6.2.2 YokeandDowelPinGrips—Aschematic diagram of a mance of the adhesive.
typical gripping device for specimens with holes drilled for pin
8. Test Specimens
loading is illustrated in Fig. 1. There should be two perpen-
dicular pins in order to maximize off axis loading.
8.1 General:
8.1.1 In order to ensure precision and accuracy in test
7. Materials
results, it is important that care be exercised in the preparation
7.1 Adhesive Bonding Agent—A polymeric adhesive bond-
of specimens, both in machining and in the case of multi-part
ing agent in film form, or filled viscous adhesive cement, when
specimens, in the assembly. Specimen components must be
used, shall be identified and shall meet the following require-
properly aligned in order that generated stresses be purely
ments.
axial, that is, normal to the coated surface.
7.1.1 The bonding agent shall be capable of bonding the
8.1.2 Tensile-Type Specimens—Three general types of test
coatingonthetestspecimencomponentswithatensilestrength
specimens are illustrated in Figs. 2 and 3. A complete,
that is at least 34.5 MPa (5000 psi) or as great as the minimum
assembledtestassemblyconsistseitheroftwosolidpieces;one
required adhesion or cohesion strength of the coating.
with a coated surface and the other with an uncoated surface or
7.1.2 In instances where porosity extends to the coating
three solid pieces; two with uncoated surfaces and one with a
substrate interface, the bonding agent shall be sufficiently
coating applied on one side. The uncoated surface may be
viscous and application to the coating sufficiently careful to
roughened to aid in the bonding of the adhesive.
assure that it will not penetrate through the coating to the
substrate. The FM 1000 Adhesive Film with a thickness of
0.25 mm (0.01 inc.) has proven satisfactory for this test. If a
Available from Cytec, Harve Grace, Maryland.
FIG. 1 Yoke and Dowel Pin Grips for Tensile Testing Porous
Surfaces FIG. 2 Tensile Specimens for Testing Porous Surfaces
F1147–99
phosphate coatings is FM-1000 having a thickness of 0.25
mm.(0.01 in.). This material has successfully been cured using
the following cycle: Where testing porous coatings, more than
one layer of glue may need to be employed.
NOTE 1—In the case of porous coatings, care must be taken to
guarantee that the adhesive does not bond to the substrate.
9.1.1 Align the adhesive with the surface of the coating,
taking precautions to align the adhesive in the center of the
coating.
9.1.2 Apply a constant force using a calibrated high tem-
perature spring, resulting in a stress of 0.138 MPa.(20 Psi.)
between the coating and the opposing device that will test the
coating.
9.1.2.1 Care must be taken to maintain alignment of the
coating and the matching counterface during the curing of the
adhesive.
9.1.3 Place the assembly in an oven and heat at 176°C
(350°F) for 2–3 h.
9.1.3.1 The exact amount of time necessary to cure the
adhesive will need to be determined by each user, as oven
temperature may vary with load size and oven type. It is
suggested that the curing cycle be optimized without the
coating present, first.
9.1.4 Remove the cured assembly from the oven and allow
FIG. 3 Smooth Tensile Specimens
it to cool to room temperature.
9.1.5 Remove all excess glue which has protruded from the
coated surface.This process must not compromise the integrity
8.1.3 The cross-sectional area of the substrate upon which
2 2
of the sample.
the coating is applied shall be nominal 5.07 cm (0.78 in ).
9.2 Placethespecimenassemblyinthegripssothatthelong
When specimens of another cross-sectional area are used, the
axis of the specimen coincides with the direction of applied
data must be demonstrated to be equivalent to a 5.07 cm
tensile load through the centerline of the grip assembly.
standard cross-sectional area, and the specimen size should be
9.3 Apply a tensile load to each test specimen at a constant
reported.
rate of cross-head speed of 0.25 cm./min.(0.10 in./min.). The
8.1.4 Alltestspecimensforcoatingcharacterizationshallbe
test should be continued until complete separation of the
prepared from indicative coating lots, using production feed-
components has been achieved. Record the maximum load
stock lots and be coated on the same equipment used for actual
applied.
implants.
8.2 Specimen Coating Preparation:
10. Calculation
8.2.1 Coatings may be applied by any one of a number of
10.1 Calculate the substrate area upon which the coating is
techniques. The coating should consist of a layer which is
2 2
applied to the nearest 0.006 cm (0.001 in. ). Record peak
mechanically or chemically attached and covers the surface.
(failure) load and calculate failing stress in MPa (psi) of
8.2.2 All thermal treatments normally performed on the
adhesive bond area as follows:
devices should be performed on the test specimens.
8.2.3 If employed, passivation and sterilization techniques
Adhesion or cohesion strength 5 maximum load/cross2section area
should be consistent with those used for actual devices. (1)
8.2.3.1 If the passivation and sterilization processes can be
11. Report
shown not to influence the tensile strength, these steps may be
eliminated.
11.1 The report shall include the following information:
8.2.4 Inspection - Before testing, visual inspections should
11.1.1 Identification of the materials used in the specimen,
be performed on 100 % of the test specimens. Lack of coating
including bonding agent if used.
in highly stressed regions, as well as non-uniform coating
11.1.2 Identification of methods used to apply the coating
appearance, shall be cause for specimen rejection.
including coating method, heat-treatment, or other data if
available, including date, cycle number, and time and tempera-
9. Procedure
ture of the run.
9.1 Specimens tested with FM1000 adhesive shall be pre- 11.1.3 Dimensional data including the bond cross-sectional
pared as follows: area and the thickness of the porous or other coated layer.
Curing the adhesive - The test results achieved are greatly 11.1.4 Number of specimens tested.
dependent upon the adhesive used and the way in which it is 11.1.5 Report all values for the failure load, including
cured. One suggested adhesive commonly used with calcium maximum, minimum, and mean.
F1147–99
11.1.6 The mode of failure (for example, cohesive versus Titanium -6 Aluminum -4 vanadium, which was hydroxylapa-
adhesive) for each test specimen. tite coated. The mean tensile strength was 8405 lbf/in (58.0)
MPa for all samples tested by all laboratories.
12. Precision and Bias
12.2.1 Repeatability—For replicate results obtained by the
same operator on nominally-identical test materials, the repeat-
12.1 Precision (beaded F75)—The precision of this method
ability standard deviation S was 1016 lbf/in (7.0 MPa). Any
was established by an interlaboratory comparison among six r
two such results (would be expected to differ by more than)
(6) laboratories. The specimens tested were sintered-bead
2845 lbf/in (19.6 MPa) only one time in 20.
coatings of F75 (Co-Cr-Mo) alloy on F75 substrates. The
12.2.2 Reproducibility—For independent results obtained
population mean tensile strength was 4325 lbf/in (29.8 MPa)
by different operators working in different laboratories on
for all samples tested by all laboratories.
nominally-identical test materials, the reproducibility standard
12.1.1 Repeatability—For replicate results obtained by the
deviation (S ) was 1758 lbf/in (12.1 MPa). Any two such
same operator on nominally-identical test materials, the repeat- R
results (would be expected to differ by more than) 4922 lbf/in
ability standard deviation (S ) was 613 lbf/in (4.23 MPa).Any
r
(33.9 MPa) only one time in 20.
two such results (would be expected to differ by more than)
1715 lbf/in (11.8 MPa) only 1 time in 20.
NOTE 3—The precision study under Section 12.2 was run using a
12.1.2 Reproducibility—For independent results obtained
cross-head speed of 0.05 in/min (0.12 cm/min).
by different operators working in different laboratories on
12.3 Bias—Since the measurement of porous-coating ten-
nominally-identical test materials, the reproducibility standard
sile strength by this method is a destructive test measurement
deviation (S ) was 772 lbf/in (5.32 MPa). Any two such
R
unique to each individual test sample, no independent deter-
results (would be expected to differ by more than) 2160 lbf/in
mination of a “correct” or “reference” value is possible. Thus,
(14.8 MPa) only 1 time in 20.
no statements regarding the deviation of values, measured in
accordance with these procedures, from accepted values is
NOTE 2—The precision study under Section 12.1 was conducted using
coupons which had a one square inch area (1.13 in. diameter). The bead
possible.
tensile strength was intentionally lowered for this round robin comparison
to produce coating fractures rather than glue failures in the coupons. 13. Keywords
12.2 Precision (HACoating)—The precision of this method 13.1 ceramic materials; hydroxylapatite; tribasic calcium
was established by an interlaboratory comparison among seven phosphate; tension testing; adherence; interface; porous
(7) laboratories. The substrate of the specimens tested was coating
ANNEXES
(Mandatory Information)
A1. PROCEDURE FOR BONDING POROUS COATED TEST SPECIMENS USING 3M SCOTCH-WELD
2214-NMF STRUCTURALADHESIVE
A1.1 Surface to be bonded must be clean, degreased, and A1.4 The specimen thus prepared will be placed in a
suitable fixture. During curing, the fixture shall be able to
free of any loose particles/beads.
maintain a mild pressure at the joint.At t
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