ASTM F2024-00

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Designation:F2024–00
Standard Practice for
X-ray Diffraction Determination of Phase Content of Plasma-
Sprayed Hydroxyapatite Coatings
This standard is issued under the fixed designation F 2024; 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 F 1185 Specification for Composition of Ceramic Hydroxy-
lapatite for Surgical Implants
1.1 This practice is for the determination, by the Reference
F 1609 Specification for Calcium Phosphate Coatings for
Intensity Ratio External Standard Method, of the percent by
Implantable Materials
weight of the crystalline phases, hydroxyapatite (HA), beta-
(whitlockite)tricalciumphosphate(b-TCP),andcalciumoxide
3. Terminology
(CaO) in coatings deposited upon metallic substrates by
3.1 Definitions:
plasma-spraying hydroxyapatite.
3.1.1 crystalline phases:
1.2 A major component in plasma-sprayed HA coatings
Chemical and Mineral Formula PDF Card No.
other than HAis expected to be amorphous calcium phosphate
Names
(ACP). Crystalline components other than HA that may be
present include alpha- and beta- (whitlockite) tricalcium phos- whitlockite b-Ca (PO ) 9-169
3 4 2
beta-tricalcium phosphate
phates, tetracalcium phosphate (TTCP), calcium oxide, and
calcium pyrophosphates. Quantification of the minor crystal-
calcium phosphate a-Ca (PO ) 9-348
3 4 2
line components has proven to be very unreliable due to alpha-tricalcium phosphate
extreme overlap and confounding of X-ray diffraction peaks.
lime CaO 37-1497
Therefore, this practice addresses the quantification of only
calcium oxide
HA, b-TCP, and CaO.
hydroxyapatite Ca (PO ) OH 9-432
5 4 3
1.3 This practice was developed for plasma-sprayed HA
(hydroxylapatite)
coatings with HAcontents of at least 50 % of the total coating.
3.2 plasma-sprayed hydroxyapatite coating—a coating,
It is recognized that the analysis of the crystalline components
consisting of at least 50 % hydroxyapatite by weight, prepared
uses diffraction from regions of the pattern that also includes a
by plasma-spraying hydroxyapatite on a substrate.
small contribution from the amorphous component. However,
within the limits of applicability of this practice, the effect of
4. Significance and Use
such interference is believed to be negligible.
4.1 Calcium phosphate coatings have been shown in animal
1.4 The coating analyzed shall be produced and processed
and clinical studies to be biocompatible and to enhance the
under equivalent manufacturing conditions to that on the
early attachment of bone to implant surfaces (see Refs. 1-5)
device of interest.
4.2 It is believed that the form of calcium phosphate
1.5 This practice requires the use of monochromated copper
ceramic and its purity with respect to secondary crystalline
Ka radiation and flat samples.
phases and amorphous material have an effect on its physical,
1.6 This standard does not purport to address all of the
mechanical, and biological properties. However, no definitive
safety concerns, if any, associated with its use. It is the
studiesofeffectsonbiologicalpropertieshavebeencompleted.
responsibility of the user of this standard to establish appro-
To achieve reproducible clinical results and to permit the
priate safety and health practices and determine the applica-
determination of the effects of properties of the coating on
bility of regulatory limitations prior to use.
biological performance, it is essential that the properties of
2. Referenced Documents
both clinical and experimental materials be well-characterized
and consistent.
2.1 ASTM Standards:
Annual Book of ASTM Standards, Vol 13.01.
ThispracticeisunderthejurisdictionofASTMCommitteeF04onMedicaland
Surgical Materials and Devices and is the direct responsibility of Subcommittee Joint Committee on Powder Diffraction Standards, Swarthmore, PA.
F04.13 on Ceramic Materials. The boldface numbers in parentheses refer to the list of references at the end of
Current edition approved May 10, 2000. Published Aug. 2000. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2024–00
4.3 This practice provides procedures for determination of overlapping peaks, a diffracted beam monochromator is re-
the percentage by weight of the crystalline phases identified as quired unless a solid-state detector is used. Linearity of the
hydroxyapatite, b-TCP and CaO in plasma-sprayed hydroxya- instrument and associated electronics must be verified daily
patite coatings. prior to utilizing this method. Use of NIST silicon powder
standard, SRM 640 is suggested.
5. Quantitative Phase Analysis by the External Standard
6.2.2 An X-ray source with a copper target is required.
Technique
Characteristic copper radiation provides the needed X-ray
5.1 The external standard technique allows the determina- diffraction peak resolution and allows for separation of peaks
tion of weight fractions of individual phases in a mixture from contaminant phases at a suitable range of diffraction
containing an amorphous fraction by comparison of the inte- angles from nominally 20 to 60° 2u. A 1.0° incident beam
grated intensity of one or more peaks from the phase(s) of divergence, a 0.2° receiving slit, and soller slits in either
interest to the external standard under identical instrumental incident or diffracted beam, or both, are suitable.
conditions (6). The sample analyzed may be a solid such as a 6.3 X-ray Method and Data Reduction Strategy:
plasma-sprayed coating or may be a powder. The mass 6.3.1 Collectadiffractionpatternfrom20to60°2uat0.02°
absorption coefficients of the sample and standard must be increments for a minimum of 1s/point.
6.3.2 X-ray diffraction peaks (or peak groups) from the
known.
5.2 The weight fraction of the analyte phase in the mixture crystalline phases must be separated in order to quantify the
HA content. The following outline provides a data reduction
is given by Equation 11 of Ref (6), as follows:
strategy in order to provide the integrated intensities necessary
hkl
I x 1
i m
W 5 · · (1) to determine the HA, b-TCP, and CaO content of mixtures of
i S D S D S D
REL Pure
x
I s I · RIR
i s i
amorphous calcium phosphate, a-TCP, b-TCP, CaO,
b-Ca P O , tetracalcium phosphate, and hydroxyapatite. Ac-
where: 2 2 7
hkl
complish the determination of integrated intensities using
I = integrated intensity of the analyte phase (hkl) peak
i
computer techniques, with least-squares fitting of the selected
or sum of peaks,
REL
I = relativeintensityoftheanalytephase(hkl)peakor peakshapetotheexperimentaldata.Manualfittingofpeakand
i
background is not permitted under this standard practice.
sum of peaks,
x = mass absorption coefficient of the mixture, 6.3.2.1 Obtain the b-TCP content by integration from 30.5
m
x = mass absorption coefficient of the standard,
to 31.5° 2u. The b-TCP peak being used for quantification is
s
Pure
I = integrated intensity of the most intense peak of the
s the(0210)peak.Thisregionisintegratedbyassumingalinear
pure standard measured under identical condi-
background and a Pearson VII functional form of the peaks
tions, and
surrounding the region.
RIR = reference intensity ratio of the analyte phase to the
i 6.3.2.2 Determine the calcium oxide content by integration
standard.
from 37.0 to 38.5° 2u and correct for the b-TCP (1 2 11) and
Values of the relative intensities, mass absorpt
...