1、Designation: F 2024 00Standard Practice forX-ray Diffraction Determination of Phase Content of Plasma-Sprayed Hydroxyapatite Coatings1This standard is issued under the fixed designation F 2024; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is for the determination, by the ReferenceIntensity Ratio External Standard Meth
3、od, of the percent byweight of the crystalline phases, hydroxyapatite (HA), beta-(whitlockite) tricalcium phosphate (b-TCP), and calcium oxide(CaO) in coatings deposited upon metallic substrates byplasma-spraying hydroxyapatite.1.2 A major component in plasma-sprayed HA coatingsother than HA is expe
4、cted to be amorphous calcium phosphate(ACP). Crystalline components other than HA that may bepresent include alpha- and beta- (whitlockite) tricalcium phos-phates, tetracalcium phosphate (TTCP), calcium oxide, andcalcium pyrophosphates. Quantification of the minor crystal-line components has proven
5、to be very unreliable due toextreme overlap and confounding of X-ray diffraction peaks.Therefore, this practice addresses the quantification of onlyHA, b-TCP, and CaO.1.3 This practice was developed for plasma-sprayed HAcoatings with HA contents of at least 50 % of the total coating.It is recognized
6、 that the analysis of the crystalline componentsuses diffraction from regions of the pattern that also includes asmall contribution from the amorphous component. However,within the limits of applicability of this practice, the effect ofsuch interference is believed to be negligible.1.4 The coating a
7、nalyzed shall be produced and processedunder equivalent manufacturing conditions to that on thedevice of interest.1.5 This practice requires the use of monochromated copperKa radiation and flat samples.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with i
8、ts use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:F 1185 Specification for Composition of Ceramic Hydroxy-lapatite for Su
9、rgical Implants2F 1609 Specification for Calcium Phosphate Coatings forImplantable Materials23. Terminology3.1 Definitions:3.1.1 crystalline phases:Chemical and MineralNamesFormula PDF Card No.3whitlockitebeta-tricalcium phosphateb-Ca3(PO4)29-169calcium phosphatealpha-tricalcium phosphatea-Ca3(PO4)2
10、9-348limecalcium oxideCaO 37-1497hydroxyapatite(hydroxylapatite)Ca5(PO4)3OH 9-4323.2 plasma-sprayed hydroxyapatite coatinga coating,consisting of at least 50 % hydroxyapatite by weight, preparedby plasma-spraying hydroxyapatite on a substrate.4. Significance and Use4.1 Calcium phosphate coatings hav
11、e been shown in animaland clinical studies to be biocompatible and to enhance theearly attachment of bone to implant surfaces (see Refs. 1-5)44.2 It is believed that the form of calcium phosphateceramic and its purity with respect to secondary crystallinephases and amorphous material have an effect
12、on its physical,mechanical, and biological properties. However, no definitivestudies of effects on biological properties have been completed.To achieve reproducible clinical results and to permit thedetermination of the effects of properties of the coating onbiological performance, it is essential t
13、hat the properties ofboth clinical and experimental materials be well-characterizedand consistent.1This practice is under the jurisdiction of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.13 on Ceramic Materials.Current edition ap
14、proved May 10, 2000. Published Aug. 2000.2Annual Book of ASTM Standards, Vol 13.01.3Joint Committee on Powder Diffraction Standards, Swarthmore, PA.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO
15、 Box C700, West Conshohocken, PA 19428-2959, United States.4.3 This practice provides procedures for determination ofthe percentage by weight of the crystalline phases identified ashydroxyapatite, b-TCP and CaO in plasma-sprayed hydroxya-patite coatings.5. Quantitative Phase Analysis by the External
16、 StandardTechnique5.1 The external standard technique allows the determina-tion of weight fractions of individual phases in a mixturecontaining an amorphous fraction by comparison of the inte-grated intensity of one or more peaks from the phase(s) ofinterest to the external standard under identical
17、instrumentalconditions (6). The sample analyzed may be a solid such as aplasma-sprayed coating or may be a powder. The massabsorption coefficients of the sample and standard must beknown.5.2 The weight fraction of the analyte phase in the mixtureis given by Equation 11 of Ref (6), as follows:Wi5SIih
18、klIiRELDSxmxsDS1IsPure RIRiD(1)where:Iihkl= integrated intensity of the analyte phase (hkl) peakor sum of peaks,IiREL= relative intensity of the analyte phase (hkl) peak orsum of peaks,xm= mass absorption coefficient of the mixture,xs= mass absorption coefficient of the standard,IsPure= integrated i
19、ntensity of the most intense peak of thepure standard measured under identical condi-tions, andRIRi= reference intensity ratio of the analyte phase to thestandard.Values of the relative intensities, mass absorption coeffi-cients, and reference intensity ratios which have been mea-sured for HA, b-TCP
20、, and CaO are given in Appendix X1.6. Procedure6.1 Sample Preparation:6.1.1 Plasma sprayed coating samples in the form of flatcoupons of nominal dimensions 2.5 by 2.5 by 0.6 cm (1 by 1by 0.125 in.) may be analyzed directly on the coated surface.The coating must be at least 44 m thick to provide a sa
21、mpleopaque to the X-ray beam. Thinner samples must be removedfrom the substrate and either deposited in a layer of at least44-m thickness and area sufficient to exceed the dimensionsof the irradiated area.6.1.2 Reliable quantitative analysis cannot be performed byX-ray diffraction on curved surfaces
22、 because of errors causedby absorption and defocusing.6.1.3 Microabsorption caused by variations in either particlesize or surface roughness will produce errors in the measureddiffracted intensity. The effective particle size and variation insurface roughness of the alpha-corundum external standardm
23、ust be less than 5 m.6.2 X-ray Equipment:6.2.1 A standard Bragg-Brentano focusing diffractometerequipped with a pyrolytic graphite monochromator is recom-mended. Because of the need to resolve closely spaced andoverlapping peaks, a diffracted beam monochromator is re-quired unless a solid-state dete
24、ctor is used. Linearity of theinstrument and associated electronics must be verified dailyprior to utilizing this method. Use of NIST silicon powderstandard, SRM 640 is suggested.56.2.2 An X-ray source with a copper target is required.Characteristic copper radiation provides the needed X-raydiffract
25、ion peak resolution and allows for separation of peaksfrom contaminant phases at a suitable range of diffractionangles from nominally 20 to 60 2u. A 1.0 incident beamdivergence, a 0.2 receiving slit, and soller slits in eitherincident or diffracted beam, or both, are suitable.6.3 X-ray Method and Da
26、ta Reduction Strategy:6.3.1 Collect a diffraction pattern from 20 to 60 2u at 0.02increments for a minimum of 1s/point.6.3.2 X-ray diffraction peaks (or peak groups) from thecrystalline phases must be separated in order to quantify theHA content. The following outline provides a data reductionstrate
27、gy in order to provide the integrated intensities necessaryto determine the HA, b-TCP, and CaO content of mixtures ofamorphous calcium phosphate, a-TCP, b-TCP, CaO,b-Ca2P2O7, tetracalcium phosphate, and hydroxyapatite. Ac-complish the determination of integrated intensities usingcomputer techniques,
28、 with least-squares fitting of the selectedpeak shape to the experimental data. Manual fitting of peak andbackground is not permitted under this standard practice.6.3.2.1 Obtain the b-TCP content by integration from 30.5to 31.5 2u. The b-TCP peak being used for quantification isthe (0 2 10) peak. Th
29、is region is integrated by assuming a linearbackground and a Pearson VII functional form of the peakssurrounding the region.6.3.2.2 Determine the calcium oxide content by integrationfrom 37.0 to 38.5 2u and correct for the b-TCP (1 2 11) and(315) peaks. This region contains the 100 % (200) calciumox
30、ide peak, and is integrated by assuming a linear form to thebackground.6.3.2.3 Finally, determine by integration the region from38.5 to 59.0 2u HA and correct for interference by b-TCP andcalcium oxide. A large angular range is used in order to use asmany peaks as possible and to reduce the effects
31、of preferredorientation. Again, this region is integrated assuming a linearform of the background.6.3.3 Perform the analysis as an external standard techniquewith reference to an alpha-corundum standard, using therelative intensities, mass absorption coefficients, and referenceintensity ratios shown
32、 in Appendix X1. Reference intensityratios determined experimentally using the equipment andconditions used for analysis of unknown samples may besubstituted for those shown, provided that their validity underthe experimental conditions used for analysis has been verifiedusing known standards. An ex
33、ample calculation is shown asAppendix X2.6.3.4 Verify the validity of the analytical procedures appliedusing known mixtures of powders ranging from nominally 50to 95 % hydroxyapatite. Conduct periodic revalidation (at least5Available from National Institute of Standards and Technology (NIST), 100Bur
34、eau Dr., Stop 3460, Gaithersburg, MD 20899-3460.F2024002annually) of instrument conditions and analytical techniqueusing retained plasma-sprayed hydroxyapatite samples.7. Report7.1 Report following information:7.1.1 Sample identification,7.1.2 Condition of analyzed sample, as-sprayed coating oncoupo
35、n or powder spalled from sample,7.1.3 Analytical results expressed as percent hydroxyapa-tite, percent b-TCP, and percent CaO relative to the entiresample,7.1.4 Balance expressed as balance-amorphous calciumphosphate (ACP) and other minor phases, and7.1.5 Statistical variability of the results based
36、 on thevariability in the RIR values (shown in Table X1.1) andinstrumental conditions.7.2 Further reporting by the device manufacturer shallinclude any treatment applied to the coating after plasma-spraying.8. Precision and Bias8.1 The precision and bias of this practice are currentlybeing determine
37、d in an interlaboratory test program. Individualexperience indicates that reproducibility is on the order of63 % for determination of the HA content of plasma-sprayedcoatings.9. Keywords9.1 amorphous calcium phosphate (ACP); hydroxyapatitecoatings; hydroxyapatite (HAP); hydroxylapatite coatings;phas
38、e analysis; tricalcium phosphate; whitlockiteAPPENDIXES(Nonmandatory Information)X1. REFERENCE VALUES FOR ANALYSISX2. EXAMPLE CALCULATIONX2.1Phase Net Intensity (after correction),counts s/b-TCP 23.9CaO 12.4HA 603.2Standard 989.0X2.2 The weight percentages are determined from Equa-tion 11 of Ref (6)
39、 with the RIR, Irel, and mass absorptioncoefficients from Appendix X1.Wb2TCP5S23.91DS87.2331.78DS1989.0 1.146D5 0.058 5 5.8 %(X2.1)WCaO5S12.41DS87.2331.78DS1989.0 3.375D5 0.010 5 1.0 %(X2.2)WHA5S603.22.16DS87.2331.78DS1989.0 1.276D5 0.607 5 60.7 %(X2.3)TABLE X1.1 Experimentally Determined Reference
40、IntensityRatios (RIR) Relative to Alpha-Corundum, aAl2O3Phase RIRHydroxyapatite (commercial powder) 1.276 6 0.001b-TCP 1.146 6 0.004CaO 3.375 6 0.004TABLE X1.2 Combined Relative Intensities for the IntegrationRegions Indicated (6)Phase Range 2u, IRelHydroxyapatite 38.5 - 59.0 2.16 6 0.02b-TCP 30.5 -
41、 31.637.0 - 38.538.5 - 59.01.00 6 0.000.145 6 0.0012.35 6 0.01CaO 37.0 - 38.538.5 - 59.01.00 6 0.001.32 6 0.007TABLE X1.3 Mass Absorption CoefficientsPhases(s) Mass Absorption CoefficientCa-P from hydroxyapatite (all phases) xm= 87.23Alpha-corundum, aAl2O3xs= 31.78F2024003REFERENCES(1) Cook, S.D., T
42、homas, K.A., Kay, J.F., and Jarcho, M.,“Hydroxylapatite-Coated Titanium for Orthopedic Implant Applica-tions,” Clinical Orthopaedics, Vol 232, 1988, p. 225.(2) Cook, S.D., Kay, J.F., Thomas, K.A., and Jarcho, M., “InterfaceMechanics and Histology of Titanium and Hydroxylapatite-CoatedTitanium for De
43、ntal Implant Applications,” International Journal ofOral and Maxillofacial Implants, Vol 2, 1987, p. 15.(3) Kent, J.N., Block, M.S., Finger, I.M., Guerra, L.S., Larsen, H., andMisiek, D.J., “Biointegrated Hydroxylapatite-Coated Dental Implants:5-Year Clinical Observations,” Journal of the American D
44、ental Asso-ciation, Vol 121, 1990, p. 138.(4) DAntonio, J.A., Capello, W.N., and Jaffe, W.L., “Hydroxylapatite-Coated Hip Implants: Multicenter Three-Year Clinical and Roentgeno-graphic Results,” Clinical Orthopaedics, Vol 285, 1992, p. 102.(5) Thomas, K.A., “Hydroxyapatite Coatings,” Orthopedics, V
45、ol 17, 1994,p. 267.(6) Prevey, P.S., and Rothwell, R.J., “X-ray Diffraction Characterization ofPercent Crystallinity and Contaminants in Plasma-Sprayed Hydroxy-lapatite Coatings,” Characterization and Performance of CalciumPhosphate Coatings for Implants, ASTM STP 1196, Emanuel Horowitzand Jack E. P
46、arr, eds., American Society for Testing and Materials,Philadelphia, PA, 1994, p. 63.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the
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49、have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F2024004
