X-ray and SEM studies on zirconia powders

Transcription

1 of Achevements n Materals and Manufacturng Engneerng VOLUME 31 ISSUE December 008 X-ray and SEM studes on zrcona powders 1. Introducton G. Dercz *, K. Prus, L. Pają Insttute of Materals Scence, Unversty of Slesa, ul. Banowa 1, Katowce, Poland * Correspondng author: E-mal address: gdercz@op.pl Receved ; publshed n revsed form ABSTRACT Methodology of research Purpose: The mcrostructure characterzaton of commercally avalable zrcona powders was the purpose of ths paper. Dfferent methods of structure analyss were appled owng to the complex, multphase structure of studed materals. Desgn/methodology/approach: The X-ray dffracton (XRD) and scannng electron mcroscopy (SEM) nvestgatons were performed on three commercal zrcona ceramc materals: Amdry 04 NS (ZrO 8 wt.% of Y O 3 ), Metco C8 YZ (ZrO 8 wt.% of Y O 3 ) and Metco 0 (ZrO 0 wt.% of Y O 3 ). The Retveld method appeared to be very useful n the verfcaton of the qualtatve phase composton and n the determnaton of phase abundance. Hll and Howard procedure was appled for quanttatve phase analyss. The parameters of the ndvdual dffracton lne profles were determned by PRO-FIT Toraya procedure. The powder morphology was analyzed by SEM method. Fndngs: In the Amdry sample comparable contents of two phases: monoclnc (44.1 wt.%) and cubc (55.9 wt.%) was stated by XRD analyss. The presence of YO3 phase besdes of monoclnc, tetragonal and cubc ZrO ones were stated for both Metco samples. The tetragonal phase (55. wt.%) was found to be the man component of the Metco C8-YZ sample whereas the content of Y O 3 s the lowest (.7 wt.%). On the other hand cubc phase (68. wt.%) was the man component of the Metco 0 sample and the content of Y O 3 s agan the lowest (4.5 wt.%). The SEM mages of all the samples reveal the sphercal shape of powder partcles. The morphology of both Metco samples s qute smlar. For Metco 0 sample the herarchcal type structure of powder partcle s observed; the greater partcles contan smaller ones. The shell of partcles s composed of dstnct patches. On the other hand the structure of sphercal partcles of Amdry sample s of branched, rather dense seleton type. From X-ray dffracton data t can be concluded that the crystallte sze of all nvolved phases les above nanoscale. Practcal mplcatons: Performed studes enable the determnaton of the relaton between the mcrostructure of commercal powders and ther utlsable propertes. Orgnalty/value: The appled, dfferent methods of structure analyss appeared to be very useful n the mcrostructure analyss of complex, multphase materal. Keywords: X-ray Phase Analyss; Electron Mcroscopy; Retveld method; Toraya procedure; Ceramcs Ceramc materals based on zrcona owng to ther propertes are of wdespread applcaton [9]. Three polymorphc forms of pure zrcona were found n equlbrum state: monoclnc below ~1170 o C, tetragonal n the temperature range ~ o C and cubc above ~370 o C. Zrcona forms of hgher symmetry have propertes very often preferable to ones of monoclnc form. Usually yttrum oxde s used as the stablzaton component of hgher symmetry zrcona forms [5]. Nanotechnology of ceramc materals based on zrcona s now of great nterestng [1,4,10,]. 408 Research paper Copyrght by Internatonal OCSCO World Press. All rghts reserved. 008

2 Methodology of research The analyss of XRD patterns was performed by the use of Retveld method [15,3,4] and Toraya procedure [19-1]. The detaled nformaton on the structure of concerned phases s necessary for the estmaton of phase abundance n multphase materals [16]. The procedure of quanttatve phase analyss based on the values of scale factors determned by Retveld refnement was ntroduced by Hll and Howard [8]. Retveld method appeared to be useful n the mcrostructure characterzaton and also n the verfcaton of the qualtatve phase composton of multphase materals [,3,5-7,11-14,17,18]. The powder morphology of studed materals was analyzed by SEM method.. Materal Materal and and research research methodology methodology Fg. 1. SEM mages of Amdry-8 sample At present the X-ray dffracton and electron mcroscopy methods are standard ones n the mcrostructure characterzaton of complex, multphase materals. X-ray dffracton methods enable qualtatve and quanttatve phase analyss and also mcrostructure characterzaton (crystallte szes, lattce dstortons, dslocaton denstes, stacng faults and twns probablty [16]). The purpose of the present wor s the mcrostructure characterzaton of three commercally avalable, zrcona-based materals usng XRD (X-Ray Dffracton) and SEM (Scannng Electron Mcroscopy) methods. The structure nvestgatons were performed on three commercal zrcona materals: Amdry 04 NS (ZrO 8 wt.% of Y O 3 ), Metco C8-YZ (ZrO 8 wt.% of Y O 3 ) and Metco 0 (ZrO 0 wt.% of Y O 3 ), hereafter called Amdry-8, Metco-8 and Metco-0, respectvely. The collecton of X-ray dffracton patterns was performed by the use X-Pert Phlps dffractometer equpped wth curved graphte monochromator on dffracted beam and wth the followng slts (n the sequence from Cu tube to counter); Soller ( o ), dvergence (1/), antscatter (1/), Soller ( o ) and recevng (0.15 mm). The X-ray data collecton was performed n 0150 o range wth 0.04 o step. The tme of data acquston was chosen to obtan the ntensty of the most ntense dffracton lne of ~0 000 counts for all X-ray patterns. Toraya PRO-FIT procedure, whch apples Pearson VII functon for the descrpton of lne profles was used for the determnaton of the profle parameters of the ndvdual dffracton lnes. The Retveld analyss was performed applyng DBWS-9807 program that s an update verson of the DBWS programs for Retveld refnement wth PC and manframe computers. The calculated ntenstes y c are determned by summng the contrbutons from neghbourng Bragg reflectons plus the bacground: y c s L F P A yb (1) where: S the scale factor, represents the Mller ndces, h,, l for the Bragg reflecton, L the Lorentz, polarzaton and multplcty factors, - the reflecton profle functon, P the preferred orentaton, A the absorpton factor, F - the structure factor for the -th Bragg reflecton, y b - the bacground ntensty at the -th step. The pseudo-vogt functon was appled for the descrbng of dffracton lne profles durng Retveld refnement. The qualty of the ft of calculated to expermental dffracton data was montored by R wp (weghted-pattern factor) and S (goodness-offt) parameters [16]. READING DIRECT: 409

3 Journal of Achevements n Materals and Manufacturng Engneerng Volume 31 Issue December 008 R wp w ( y y w ( y ) 1 c 1/ ) 100% N P R exp 100% w y (3) w ( y yc ) S N P (4) where: y the expermental ntenstes, y c the calculated ntenstes, w = ( 1/y ) the weght expermental observatons, N the number of expermental observatons, P the number of fttng parameters. The process of successve profle refnements modulates dfferent structural and mcrostructural parameters of the smulated pattern to ft the expermental dffracton pattern. Profle refnement contnues untl convergence s reached n each case, wth the value of the qualty factor (S) approachng 1. The phase abundance was determned usng the relaton proposed by Hll and Howard[4]: W p S p n S Z M V Z M V 100% 1 (5) where: W p relatve weght fracton of phase p n the mxture of n phases (wt. %), S Retveld scale factor, Z number of formula unts per unt cell, M mass of the formula unt (n atomc mass unts), V unt cell volume (n Å 3 ).Morphology of the powder partcles was analyzed usng SEM (JEOL JSM-6480) method. 3. Results and and dscusson dscusson () Scannng electron mcroscopy mages reveal the sphercal shape of powder partcles for all studed samples (Fgs. 1-3). Dfferences n ther morphology can be found from the analyss of the correspondng mages obtaned at dfferent magnfcaton. For Amdry-8 sample the partcle sze dstrbutons loos le bmodal wth preferable partcle szes of ~0 m and ~40 m. The mage presented n Fg. 1c ndcates the branched, rather dense, seleton type structure of Amdry-8 powder partcles wth bacbone thcness of ~0.5 m. The SEM mages of the Metco samples (Fgs. and 3) show generally the smlar morphology of ther powder partcles. The surface layer of partcles s slghtly folded and s covered by dstnct patches (Fgs. c and 3c). The partcle sze dstrbutons of both Metco powders s rather broad wth partcle dameters n the range from ~8 m to ~70 m. For Metco-0 powder (Fg. 3a) the herarchcal structure type of greater partcles can be postulated; the greater partcles contan the smaller ones. Such type of structure cannot be excluded for Metco-8 sample but s less probable for Amdry-8 one. Fg.. SEM mages of Metco-8 sample Analyss of the X-ray dffracton pattern of Amdry-8 sample reveals the presence of monoclnc and cubc zrcona phases (Fg. 4). In both Metco samples the monoclnc, tetragonal and cubc ZrO phases and Y O 3 one were found (Fgs. 5 and 6). The contents of all nvolved phases determned by Hll and Howard procedure [4] are presented n Tables 1-3. The accuracy of the determnaton of phase contents s dffcult to estmaton but should be relatvely hgh because the man components of the studed materals are the phases of the same absorpton 410 Research paper G. Dercz, K. Prus, L. Pają

4 Methodology of research coeffcent. Comparatvely loose structure of powder partcles and partcle szes enable ther good penetraton by X-rays. In Amdry-8 sample the contents of both cubc and monoclnc zrcona phases are comparable and equal to ~55.9 and ~44.1 wt.%, respectvely; the presence of Y O 3 phase was not found by X-ray dffracton. Fg. 4. X-ray dffracton pattern of Amdry-8 sample Fg. 5. X-ray dffracton pattern of Metco-8 sample Fg. 6. X-ray dffracton pattern of Metco-0 sample Fg. 3. SEM mages of Metco-0 sample The tetragonal zrcona phase appeared to be the man component of Metco-8 sample (55. wt.%). The content of cubc form s stll relatve hgh (36.6 wt.%) whereas of tetragonal one s relatvely low (7.5 wt.%); the content of Y O 3 phase s the lowest (.7 wt.%). Thus, above results ndcate hgh contents of hgh symmetrcal zrcona phases n Metco-8 sample. X-ray and SEM studes on zrcona powders 411

5 Journal of Achevements n Materals and Manufacturng Engneerng Volume 31 Issue December 008 The cubc zrcona phase appeared to be the man component of Metco-0 sample (68. wt.%). The content of monoclnc zrcona phase s relatve hgh and equal to.3 wt.%. The contents of tetragonal zrcona phase and Y O 3 one are comparable and relatvely low (5.0 and 4.5 wt.% respectvely). Table 1. Lattce parameters and the contents of components for Amdry-8 sample (8 wt.% of Y O 3 ) Phase Space Lattce parameters [nm] Contents group Retveld ICDD [wt.%] ZrO P 1 /c a 0 = (8) a 0 = (4) b 0 = (8) b 0 = 0.508(4) c 0 = (8) c 0 = (4) 44.1 = ZrO Fm3m a 0 = (8) a 0 = Fg. 7. Retveld output of X-ray dffracton pattern for Amdry-8 sample Table. Lattce parameters and the contents of components for Metco 1 sample (8 wt.% of Y O 3 ) Phas e ZrO P 1 /c Space Lattce parameters [nm] group Retveld ICDD a 0 = (8) a 0 = (4) b 0 = (8) b 0 = 0.508(4) c 0 = (8) c 0 = (4) Contents [wt.%] 7.5 = ZrO Fm3m a 0 = (8) a 0 = P4 a 0 = (6) a 0 = (1) ZrO /nm c c 0 = (8) c 0 = () 55. Y O 3 Ia3 a 0 = () a 0 = (5).7 Table 3. Lattce parameters and the contents of components for Metco sample (0 wt.% of Y O 3 ) Phase Space Lattce parameters [nm] Contents group Retveld ICDD [wt.%] ZrO P 1 /c a 0 = (8) a 0 = (4) b 0 = (8) b 0 = 0.508(4) c 0 = (8) c 0 = (4).3 = ZrO Fm3m a 0 = (8) a 0 = P4 a 0 = (6) a 0 = (1) ZrO /nm c c 0 = (8) c 0 = () 5.0 Y O 3 Ia3 a 0 = () a 0 = (5) 4.5 Fg. 8. Retveld output of X-ray dffracton pattern for Metco-8 sample The low content of Y O 3 phase (4.5 wt.%) means that meanng part of ths phase s ntercorporated nto zrcona phases (nomnal content of Y O 3 phase n Metco-0 sample s 0 wt.%). The crystallte sze of all phases found n studed materals les above nanoscale. The values of lattce parameters determned by Retveld method and these found n ICDD fles for all concerned phases are gven n Tables 1-3; generally good agreement between them can be seen. The accuracy of the lattce parameter determnaton (equal to 0.015%) was estmated usng SRM 1976 alumna plate as a standard. Fg. 9. Retveld output of X-ray dffracton pattern for Metco-0 sample The values of lattce parameters of all zrcona phases are very close (Tables 1-3); moreover the lattce constant of Y O 3 phase are about twce of these of zrcona phases. It means the overlappng of dffracton lnes of all phase present n studed 41 Research paper G. Dercz, K. Prus, L. Pają

6 Methodology of research materals. The Retveld method by the analyss of the whole dffracton patterns enables good separaton of dffracton lnes and thus appears especally useful n the analyss of actually studed materals. The Retveld refnement plots for studed samples are presented n Fgs The goodness of fttng of calculated patterns to the expermental ones can be regarded as satsfactory Conclusons Scannng electron mages reveal the sphercal shape of powder partcles for all studed samples. The structure of powder partcles of Amdry-8 sample s of branched, dense, seleton type. The morphology of both Metco samples s qute smlar but dfferent to observed for Amdry-8 sample. The surface of powder partcles s slghtly folded and s covered by dstnct patches. The herarchcal structure type of greater partcles s observed for Metco-0 sample; the greater partcles contan the smaller ones. In Amdry-8 sample the cubc and monoclnc zrcona phases are present and ther contents are comparable and equal to 55.9 and 44.1 wt.%, respectvely. The presence of four phases: cubc, tetragonal and monoclnc zrcona and Y O 3, n both Metco samples, was stated. It was found that n Metco-8 sample the content of tetragonal zrcona phase s the hghest (55. wt.%), whereas of Y O 3 one s the lowest (.7 wt.%). The content of monoclnc zrcona s relatvely low (7.5 wt.%). In Metco-0 sample the content of cubc zrcona phase s the hghest (68. wt.%), whereas of Y O 3 one s the lowest (4.5 wt.%). The content of monoclnc zrcona phase s stll relatve hgh (.3 wt.%). The crystallte sze of all phases found n studed materals les above nanoscale. Good agreement of lattce parameters determned by Retveld refnement method and these from ICDD fles was obtaned for all nvolved phases. Retveld refnement method and PRO-FIT Toraya procedure appeared to be very useful n the characterzaton of complex, multphases materals. Acnowledgements Ths wor s fnancally supported by State Commttee for Scentfc Research (grant PBZ/KBN 3T08A0177). References [1] U. Betz, A. Sturm, J.F. Loeffler, W. Wagner, A. Wedenmann, H. Hahn, Low-temperature sothermal snterng and mcrostructural characterzaton of nanocrystallne zrcona ceramcs usng small angle neutron scatterng, Nanostructured Materals 1 (1999) [] D.L. Bsh, S.A. Howard, Quanttatve phase analyss usng the Retveld method, Journal of Appled Crystallography 1 (1988) [3] D.L. Bsh, J.E. Post, Quanttatve mneralogcal analyss usng the Retveld full-pattern fttng method, Amercan Mneralogst 78 (1993) [4] X. Bohm, A. Morales, O. Novaro, M. Portlla, T. Lopez, F. Tzoompantz, R. Gomez, Tetragonal nanophase stablzaton n nondoped Sol Gel zrcona prepared wth dfferent hydrolyss catalysts, Journal of Sold State Chemstry 135 (1998) [5] G. Dercz, B. Formane, K. Prus, L. Paj, Mcrostructure of N(Cr)-TC-Cr 3 C -Cr 7 C 3 composte powder, Journal of Materals Processng Technology (005) [6] G. Dercz, B. Formane, K. Prus, L. Paj, Mcrostructure of N(Cr)-TC-Cr 3 C -Cr 7 C 3 composte powder, Proceedngs of the 13 th Scentfc Internatonal Conference Achevements n Mechancal and Materals Engneerng AMME 005, GlwceZaopane, 005, [7] G. Dercz, K. Prus, L. Paj, Structure nvestgatons of commercal zrcona ceramc powder, Journal of Achevements n Materals and Manufacturng Engneerng 18 (006) [8] R.J. Hll, C.J. Howard, Quanttatve phase analyss from neutron powder dffracton data usng the Retveld method, Journal of Appled Crystallography 0 (1987) [9] W. Kurzweg, R.B. Hemann, T. Troczys, M.L. Waymann, Development of plasma sprayed boceramc coatngs wth bond coats based on ttana and zrcona, Bomaterals 19 (1998) [10] R. Ntsche, M. Wnterer, H. Hahn, Structure of nanocrystallne zrcona and yttra, Nanostructured Materals 6 (1995) [11] B.H. O Connor, M.D. Raven, Applcatons of the Retveld refnement procedure n assayng powdered mxtures, Powder Dffracton,3 (1988) -6. [1] L. Paj, B. Formane, G. Dercz, Retveld analyss of ntermetallc phases from N-Al system, Proceedngs of the 11 th Scentfc Internatonal Conference Achevements n Mechancal and Materals Engneerng AMME 00, GlwceZaopane, 00, [13] L. Paj, B. Formane, G. Dercz, Dsperson analyss of NAl-TC-Al O 3 composte powder, Proceedngs of the 1 th Scentfc Internatonal Conference Achevements n Mechancal and Materals Engneerng AMME 003, GlwceZaopane, 003, [14] L. Paj, B. Formane, G. Dercz, Dsperson analyss of NAl-TC-Al O 3 composte powder ground n hgh-energy attrtoral mll, Journal of Materals Processng Technology 175 (006) [15] H.M. Retveld, A profle refnement method for nuclear and magnetc structures, Journal of Appled Crystallography (1969) [16] R.L. Snyder, J. Fala, H.J. Bunge, Defects and mcrostructure analyss by dffracton, EDS IUCr Monographs on Crystallography 10, Oxford Unversty Press Inc., New Yor, [17] J.C. Taylor, Computer programs for standardless quanttatve analyss of mnerals usng the full powder dffracton profle, Powder Dffracton 6 (1991) -9. X-ray and SEM studes on zrcona powders 413

7 Journal of Achevements n Materals and Manufacturng Engneerng Volume 31 Issue December 008 [18] J.C. Taylor, C.E. Matuls, Use of a unversally measured standard profle for Retveld quantfcaton of montmorllontes, Powder Dffractometry 9 (1994) [19] H. Toraya, Array type unversal profle functon for powder pattern fttng, Journal of Appled Crystallography 19 (1986) [0] H. Toraya, Whole-Powder-Pattern Fttng wthout reference to a structural model applcaton to X-ray powder dffractometer data, Journal of Appled Crystallography 19 (1986) [1] H. Toraya, Whole-Powder-Pattern decomposton method, The Rgau Journal 6 (1989) [] J.A. Wang, M.A. Valenzuela, J. Salmones, A. Vazquez, A. Garca-Ruz, X. Bohm, Comparatve study of nanocrystallne zrcona prepared by precptaton and solgel methods, Catalyss Today 68 (001) [3] R.A. Young, D.B. Wles, Applcaton of the Retveld methods for structure refnement wth powder dffracton data, Advances n X-Ray Analyss 4 (1980) 1-3. [4] R.W. Young, The Retveld method, IUCr Monograph on Crystallography, Oxford Scence Publshng, [5] W.Z. Zhu, Effect of cubc phase on the netcs of the sothermal tetragonal to monoclnc transformaton n ZrO (3mol%Y O 3 ) ceramcs, Ceramcs Internatonal 4 (1998) Research paper G. Dercz, K. Prus, L. Pają