1、Designation: F2024 10 (Reapproved 2016)Standard Practice forX-ray Diffraction Determination of Phase Content of Plasma-Sprayed Hydroxyapatite Coatings1This standard is issued under the fixed designation F2024; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is for the determination, by the ReferenceIntensity Ratio Externa
3、l Standard Method, of the percent byweight of the crystalline phases, hydroxyapatite (HA), beta-(whitlockite) tricalcium phosphate (-TCP), and calcium oxide(CaO) in coatings deposited upon metallic substrates byplasma-spraying hydroxyapatite.1.2 A major component in plasma-sprayed HA coatingsother t
4、han HA is expected to be amorphous calcium phosphate(ACP). Crystalline components other than HA that may bepresent include alpha- and beta- (whitlockite) tricalciumphosphates, tetracalcium phosphate (TTCP), calcium oxide,and calcium pyrophosphates. Quantification of the minorcrystalline components h
5、as proven to be very unreliable due toextreme overlap and confounding of X-ray diffraction peaks.Therefore, this practice addresses the quantification of onlyHA, -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 r
6、ecognized 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
7、coating analyzed shall be produced and processedunder equivalent manufacturing conditions to that on thedevice of interest.1.5 This practice requires the use of monochromated copperK radiation and flat samples.1.6 The values stated in SI units are to be regarded asstandard. No other units of measure
8、ment are included in thisstandard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its 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 limita
9、tions prior to use.2. Terminology2.1 Definitions:2.1.1 crystalline phases:Chemical and MineralNamesFormula PDF Card No.2whitlockitebeta-tricalcium phosphate-Ca3(PO4)29-169calcium phosphatealpha-tricalcium phosphate-Ca3(PO4)29-348limecalcium oxideCaO 37-1497hydroxyapatite(hydroxylapatite)Ca5(PO4)3OH
10、9-4322.2 plasma-sprayed hydroxyapatite coatinga coating,consisting of at least 50 % hydroxyapatite by weight, preparedby plasma-spraying hydroxyapatite on a substrate.3. Significance and Use3.1 Calcium phosphate coatings have been shown in animaland clinical studies to be biocompatible and to enhanc
11、e theearly attachment of bone to implant surfaces (see Refs. 1-5)33.2 It is believed that the form of calcium phosphateceramic and its purity with respect to secondary crystallinephases and amorphous material have an effect on its physical,mechanical, and biological properties. However, no definitiv
12、estudies 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 that the properties ofboth clinical and experimental materials be well-charac
13、terizedand consistent.1This practice is under the jurisdiction ofASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.13 on Ceramic Materials.Current edition approved Oct. 1, 2016. Published October 2016. Originallyapproved in 2000. Last
14、 previous edition approved in 2010 as F2024 10. DOI:10.1520/F2024-10R16.2Joint Committee on Powder Diffraction Standards, Swarthmore, PA.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, W
15、est Conshohocken, PA 19428-2959. United States13.3 This practice provides procedures for determination ofthe percentage by weight of the crystalline phases identified ashydroxyapatite, -TCP and CaO in plasma-sprayed hydroxy-apatite coatings.4. Quantitative Phase Analysis by the External StandardTech
16、nique4.1 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 instrumentalc
17、onditions (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.4.2 The weight fraction of the analyte phase in the mixtureis given by Equation 11 of Ref (6), as follows:Wi5SIihklIiRELDSmsDS
18、1IsPureRIRiD(1)where:Iihkl= integrated intensity of the analyte phase (hkl) peak orsum of peaks,IiREL= relative intensity of the analyte phase (hkl) peak orsum of peaks,m= mass absorption coefficient of the mixture,s= mass absorption coefficient of the standard,IsPure= integrated intensity of the mo
19、st intense peak of thepure standard measured under identical conditions,andRIRi= reference intensity ratio of the analyte phase to thestandard.Values of the relative intensities, mass absorptioncoefficients, and reference intensity ratios which have beenmeasured for HA, -TCP, and CaO are given in Ap
20、pendix X1.5. Procedure5.1 Sample Preparation:5.1.1 Plasma-sprayed coating samples in the form of flatcoupons of nominal dimensions 2.5 by 2.5 by 0.6 cm may beanalyzed directly on the coated surface. The coating must be atleast 44 m thick to provide a sample opaque to the X-raybeam. Thinner samples m
21、ust be removed from the substrateand either deposited in a layer of at least 44-m thickness andarea sufficient to exceed the dimensions of the irradiated area.5.1.2 Reliable quantitative analysis cannot be performed byX-ray diffraction on curved surfaces because of errors causedby absorption and def
22、ocusing.5.1.3 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 standardmust be less than 5 m.5.2 X-ray Equipment:5.2.1
23、 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 detector is used. Linearity of theinstrument and a
24、ssociated electronics must be verified dailyprior to utilizing this method. Use of NIST silicon powderstandard, SRM 640 is suggested.45.2.2 An X-ray source with a copper target is required.Characteristic copper radiation provides the needed X-raydiffraction peak resolution and allows for separation
25、of peaksfrom contaminant phases at a suitable range of diffractionangles from nominally 20 to 60 2. A 1.0 incident beamdivergence, a 0.2 receiving slit, and soller slits in eitherincident or diffracted beam, or both, are suitable.5.3 X-ray Method and Data Reduction Strategy:5.3.1 Collect a diffracti
26、on pattern from 20 to 60 2 at 0.02increments for a minimum of 1s/point.5.3.2 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 reductionstrategy in order to provide the integrated intensitie
27、s necessaryto determine the HA, -TCP, and CaO content of mixtures ofamorphous calcium phosphate, -TCP, -TCP, CaO,-Ca2P2O7, tetracalcium phosphate, and hydroxyapatite. Ac-complish the determination of integrated intensities usingcomputer techniques, with least-squares fitting of the selectedpeak shap
28、e to the experimental data. Manual fitting of peak andbackground is not permitted under this standard practice.5.3.2.1 Obtain the -TCP content by integration from 30.5to 31.5 2. The -TCP peak being used for quantification isthe (0 2 10) peak. This region is integrated by assuming a linearbackground
29、and a Pearson VII functional form of the peakssurrounding the region.5.3.2.2 Determine the calcium oxide content by integrationfrom 37.0 to 38.5 2 and correct for the -TCP (1 2 11) and(315) peaks. This region contains the 100 % (200) calciumoxide peak, and is integrated by assuming a linear form to
30、thebackground.5.3.2.3 Finally, determine by integration the region from38.5 to 59.0 2 HA and correct for interference by -TCP andcalcium oxide. A large angular range is used in order to use asmany peaks as possible and to reduce the effects of preferredorientation. Again, this region is integrated a
31、ssuming a linearform of the background.5.3.3 Perform the analysis as an external standard techniquewith reference to an alpha-corundum standard, using therelative intensities, mass absorption coefficients, and referenceintensity ratios shown in Appendix X1. Reference intensityratios determined exper
32、imentally 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 example calculation is shown asAppendix X2.5.3.4 Verify the v
33、alidity of the analytical procedures appliedusing known mixtures of powders ranging from nominally 50to 95 % hydroxyapatite. Conduct periodic revalidation (at least4Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.
34、nist.gov.F2024 10 (2016)2annually) of instrument conditions and analytical techniqueusing retained plasma-sprayed hydroxyapatite samples.6. Report6.1 Report following information:6.1.1 Sample identification,6.1.2 Condition of analyzed sample, as-sprayed coating oncoupon or powder spilled from the sa
35、mple,6.1.3 Analytical results expressed as percenthydroxyapatite, percent -TCP, and percent CaO relative to theentire sample,6.1.4 Balance expressed as balance-amorphous calciumphosphate (ACP) and other minor phases, and6.1.5 Statistical variability of the results based on thevariability in the RIR
36、values (shown in Table X1.1) andinstrumental conditions.6.2 Further reporting by the device manufacturer shallinclude any treatment applied to the coating after plasma-spraying.7. Precision and Bias7.1 The precision and bias of this practice are currentlybeing determined in an interlaboratory test p
37、rogram. Individualexperience indicates that reproducibility is on the order of63 % for determination of the HA content of plasma-sprayedcoatings.8. Keywords8.1 amorphous calcium phosphate (ACP); hydroxyapatitecoatings; hydroxyapatite (HAP); hydroxylapatite coatings;phase analysis; tricalcium phospha
38、te; whitlockiteAPPENDIXES(Nonmandatory Information)X1. REFERENCE VALUES FOR ANALYSISTABLE X1.1 Experimentally Determined Reference IntensityRatios (RIR) Relative to Alpha-Corundum, Al2O3Phase RIRHydroxyapatite (commercial powder) 1.276 0.001-TCP 1.146 0.004CaO 3.375 0.004TABLE X1.2 Combined Relative
39、 Intensities for the IntegrationRegions Indicated (6)Phase Range 2, IRelHydroxyapatite 38.5 - 59.0 2.16 0.02-TCP 30.5 - 31.637.0 - 38.538.5 - 59.01.00 0.000.145 0.0012.35 0.01CaO 37.0 - 38.538.5 - 59.01.00 0.001.32 0.007TABLE X1.3 Mass Absorption CoefficientsPhases(s) Mass Absorption CoefficientCa-P
40、 from hydroxyapatite (all phases) m= 87.23Alpha-corundum, Al2O3s= 31.78F2024 10 (2016)3X2. EXAMPLE CALCULATIONX2.1Phase Net Intensity (after correction),counts s/-TCP 23.9CaO 12.4HA 603.2Standard 989.0X2.2 The weight percentages are determined from Equation11 of Ref (6) with the RIR, Irel, and mass
41、absorption coeffi-cients from Appendix X1.W2TCP5S23.91DS87.2331.78DS1989.01.146D5 0.058 5 5.8%(X2.1)WCaO5S12.41DS87.2331.78DS1989.03.375D5 0.010 5 1.0%(X2.2)WHA5S603.22.16DS87.2331.78DS1989.01.276D5 0.607 5 60.7%(X2.3)REFERENCES(1) Cook, S.D., Thomas, K.A., Kay, J.F., and Jarcho, M.,“Hydroxylapatite
42、-Coated Titanium for Orthopedic ImplantApplications,” 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 Dental Implant Applications,” International Journal ofOral
43、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 DentalAssociation, Vol 121, 1990, p. 138.(4) DAntonio, J.A
44、., Capello, W.N., and Jaffe, W.L., “Hydroxylapatite-Coated Hip Implants: Multicenter Three-Year Clinical and Roent-genographic Results,” Clinical Orthopaedics, Vol 285, 1992, p. 102.(5) Thomas, K.A., “Hydroxyapatite Coatings,” Orthopedics, Vol 17,1994, p. 267.(6) Prevey, P.S., and Rothwell, R.J., “X
45、-ray Diffraction Characterizationof Percent Crystallinity and Contaminants in Plasma-Sprayed Hy-droxylapatite Coatings,” Characterization and Performance of Cal-cium Phosphate Coatings for Implants, ASTM STP 1196, EmanuelHorowitz and Jack E. Parr, eds., American Society for Testing andMaterials, Phi
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