Nacre Coatings Deposited by Electrophoresis on Ti6Al4V

8/2/2019 Nacre Coatings Deposited by Electrophoresis on Ti6Al4V

1/8

Avai la b le on li ne a t www.sciencedirect.com-"-;;" ScienceD irect S U R F A C E& C O A T I N S SH G H N O L D G YELSEVIER Surface & Coatings Technology 201 (2007) 7505 - 7512 www.elsevier.comllocate/surfcoat

Nacre coatings deposited by electrophoresis on Ti6Al4V substratesYP. Guo, Y Zhou *

Insti tute for Advanced Ceramics, Harbin Institute of Technology, Harbin 150001, ChinaReceived 3 August 2006; accepted in revised form 12 February 2007

Available online 21 February 2007

AbstractCrack-free nacre coatings on titanium alloys were produced by electrophoretic deposition in a nacre/ethanol suspension with or without a

hydrochloric acid (HCI) additive. The microstructure and morphology of coatings were investigated by X-ray diffraction (XRD), Fouriertransform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The deposition yield of nacre powders was determined byweighting the dried deposits. The results show that the HCI additive has no obvious effects on the crystalline phase of nacre coatings. Thedeposition yield of nacre powders increases with adding acid additives, prolonging deposition time, and improving applied voltage. A uniform andglue-like nacre coating is deposited in a suspension with the HCI additive via a dissolution-precipitation reaction. After the HCI additive is addedinto a nacre/ethanol suspension, calcium ions are released from nacre powder surfaces, and move toward the cathode within an electric field. Thelocal concentrations of hydroxide ions and carbonate ions increase due to the reduction of hydrogen ions at the cathode surface. Calcium ions reactwith carbonate ions to form calcium carbonate as the ionic activity product exceeds its thermodynamic solubility product, and re-precipitates onthe active sites of nacre powder surfaces. 2007 Elsevier B.Y. All rights reserved.Keywords: Electrophoretic deposition; Coatings; Nacre; Titanium; Dissolution-precipitation reaction

1. IntroductionNacre (mother of pearl) is a natural composite material

composed of alternating layers of aragonite (CaC03) and abiopolymer [1]. One or more signal molecules in nacrebiopolymers, like bone morphogenetic proteins (BMPs), arecapable of activating osteogenic bone marrow cells leading tobone formation [2]. Nacre can support human osteoprogenitorcell attachment, migration, growth and differentiation in vitroand in vivo. New bone is directly formed on the surfaces of nacreimplant without any soft tissue intervention [3]. Therefore, nacreis considered a promising osteoinductive material for bone graftsubstitutes and for the correction of bone irregularities.However, the intrinsic shape and size of shell nacre hinder itswide applications in hard tissue replacement materials.

This drawback can be overcome by depositing nacrepowders on metallic materials (e.g., titanium alloys, stainless

* Corresponding author. Present address: P. O. Box 433, School of MaterialsScience and Engineering, Harbin Insti tute of Technology, Harbin 150001, PRChina. Tel.lfax: +86 451 86414291.

E-mail address:[email protected] (Y. Zhou).0257-8972/$ - see front matter 2007 Elsevier B.V. All r ights reserved.doi: I 0.10 16/j.surfcoat.2007.02.021

steels, tantalum, and cobalt-chromium-molybdenum alloys),which exhibit excellent mechanical properties under load-bearing conditions [4,5]. Nacre coatings on inert metallicimplants are not only bioactive and biodegradable, but alsomechanically robust [6]. Such coatings have been obtained bydiverse deposition techniques, including plasma spraying [7],hydrothermal hot-pressing method [8], biological fabrication[6], and electrophoresis technique [9,10]. Among thesetechniques, plasma spraying is one of most common methodsfor coating implant parts with bioceramics, but it is performedusually at near 10,000 C over the decomposed temperature ofnacre [11]. Hydrothermal hot-pressing method is a line-of-sightprocess; thus it is difficult to apply uniform coatings on implantswith complex geometries [12]. Electrophoretic depositionrepresents an important technological alternative due to rapidcoatings production, high reproducibility, low processing cost,and the possibility of forming coatings with complex shape andpatterns [9,13,14]. A high degree of control of coating depositthickness and morphology can be obtained by adjusting thedeposition conditions and bioceramic powder size and shape.Moreover, the proteins inside nacre powders can be preservedafter electrophoretic deposition [15].
http://www.sciencedirect.com/http://www.elsevier.comllocate/surfcoatmailto:address:[email protected]:address:[email protected]://www.elsevier.comllocate/surfcoathttp://www.sciencedirect.com/


2/8

7506 YP Guo, Y Zhou / Surface & Coatings Technology 201 (2007) 7505-7512

However, electrophoretic coatings have the major drawbackof poor adhesion as compared with plasma spraying or thermalspraying [16]. These coatings must be posttreated by densifica-tion at about 1200 C [17]. Such high temperatures not onlydeteriorate the mechanical properties of metal implants [18], butalso cause decomposition of nacre coatings. Fortunately, acidpretreatment is an important substituted method to overcomethis drawback. A Tif), layer with a homogeneous roughlymicrotopography is created on a substrate surface after chemicalpretreatment. The bonding strength between substrates andcoatings is improved by micromechanical interlocking bonding[19]. Moreover, the Tif), layer obtained on titanium alloys canimprove corrosion resistance and induce bonelike apatiteformation [20].

The deposition rate of electrophoresis is influenced by theZeta potential (() and the conductivity of suspensions. Previousstudies [17] have shown that the addition of acid or alkaline(HN03 or NH40H) can obtain an ideal and stable suspensionfor deposition of bioceramic particles and improve itsconductivity. In our studies, we find that the addition ofhydrochloric acid (HCI) not only increases the deposition rate,but also alters the morphology of nacre coatings.

In this work, Ti6Al4V substrates were pretreated by a1.0 molll H3P04-1.5 wt.% HF solution to form a Tit), layer onsubstrate surfaces. Nacre coatings were deposited on Ti6Al4Vsubstrates by electrophoretic technique in a nacre/ethanolsuspension with or without acid additives. The effect of acidadditives on nacre coatings was investigated by using X-raydiffraction (XRD), Fourier transform infrared spectroscopy(FTIR), and scanning electron microscopy (SEM).2. Experimental procedure

Hydrochloric acid and ethanol were purchased from TianjinYaohua Chemical Reagent CO., Ltd., and phosphate acid fromTianjin Tianli Chemical Reagent CO., Ltd., and hydrofluoricacid from Harbin Chemical Reagent Plant, and nitric acid fromBeijing Chemical Plant. These reagents are all of analyticalgrade and used as received without further purification.Titanium alloys (Ti6AI4V) substrates were purchased fromBaoji Tiint Medical Ti CO., Ltd.

The nacre of Corbicula jluminea was collected fromZhejiang province in China, composed of 98.1 % calciumcarbonate in the aragonite form. Nacre powders were obtainedby the following procedure. Briefly, the shell of C . jlumineawas cleaned of macroscopic impurities in tap water using abrush, and the nacre was separated from the shell by shaving offthe outer layers including periostracum and prismatic layer.Then the nacre was sonicated for 5 min, washed with deionizedwater and air-dried. Finally, the nacre obtained was ground intopowders in a mortar.

Standard structure titanium alloys (Ti6AI4V), 15x 15 x0.9 mm ' in size, were used for substrate materials. Before de-position, titanium alloys were abraded with 1OOO-gritSiC paper,and washed with pure acetone and deionized water in anultrasonic cleaner. Acid treatment was performed by soakingthese substrates in a 1.0 molll H3P04 -1.5 wt. % HF solution for

20 min at room temperature, to form Tit), gel on their surfaces.After acid treatment, the substrates were gently washed withdeionized water, and dried at room temperature in an airatmosphere.

To deposit nacre powders on substrates, an electrophoreticcell using Ti6Al4V as cathode and graphite plate as anode wasmounted, with two electrodes about 10 mm apart. Three parts ofnacre/ethanol suspensions with 1.25 g of solid powders in250 ml of ethanol were prepared, and then ultrasonicallydispersed for 30 min. In the first part, 0.5 ml of 1.0 molll HCIsolution (HCI additive) was added into the nacre/ethanolsuspension before deposition; in the second part, 0.5 ml of1.0 molll HN03 solution (HN03 additive) was added into thesuspension; in the third part, no acid additive was added. Iftherewas no special station, the electrophoretic process was carriedout at 90 V for 1 min. After deposition, the coatings obtainedwere dried in a convection oven at 37C for 48 h.The morphologies of nacre coatings and Ti6Al4V substrateswere investigated by scanning electron microscopy (SEM, S-4800, Hitachi) equipped with energy dispersive X-ray spectro-scopy (EDX). X-ray photoelectron spectroscopies (XPS,PHI5700 ESCA) of samples were obtained by using analuminum anode (AI Ko =1486.6 eV radiation) at a pressureof 2 x 10-7 Torr. The binding energies of the atoms were cali-brated against aC Is of284.6 ev' The crystalline phases of nacrecoatings and titanium alloys were examined with X-ray powderdiffraction (XRD, D/max-II B) using Cu Ko radiation. FourierTransform Infrared spectra (FTIR, VECT0R22, BRUKER)were collected at room temperature using the KEr pellet tech-nique working in the range of wave numbers 4000~400 em-[ ata resolution of 2 em-[ (number of scans ~ 60).3. Results and discussion3.1. Characterization of titanium alloys and nacre coatings

The major drawback of electrophoretic deposition is theweak bonding strength between coatings and substrates. In ourstudies, we find that nacre powders are deposited difficultly onthe substrates without any pretreatment, and nacre coatings slideeasily from the substrate surfaces. Acid pretreatment is one ofthe important methods to overcome this drawback. Fig. 1 showsthe SEM micrographs of titanium alloys before and aftersoaking in a 1.0 molll H3P04-1.5 wt.% HF solution for 20 min.A homogeneous rough microtopography on substrate surface iscreated after chemical pretreatment. Fig. 2 shows that Ti and 0originate from TiOx, and C originates from common organiccontamination absorbed to the substrate surface [21]. The Tii),layer is found to be amorphous as evidenced by the absence ofcharacteristic peaks of Tit); crystals in Fig. 3a. Previous studieshave shown that Tit), (Ti02, Ti203) can inhibit the movementof cells to implant surfaces and play an important role infacilitating osteointegration due to its high dielectric constants[22]. V and Al are harmful to the biocompatibility of Ti6Al4Vsubstrates. Fortunately, the V and Al originating from theTi6Al4V substrates are barely detected in Fig. 2. The mainreason is that the V and Al metals on Ti6Al4V surfaces react


3/8

YP Guo, Y Zhou / Surface & Coatings Technology 201 (2007) 7505-7512

Fig. I . SEM micrographs of Ti6AI4V substrates: (a)before soaking in a 1.0 mol/I H3POc.5 wt.% HF solution; (b) after soaking for 20 min.

with HF or H3P04 to form AI3+, AIF~- and so on, and then enterinto the solution.

Fig. 3b and c shows XRD patterns of nacre coatingsdeposited by electrophoresis technique with or without the HCI

o(a)

1200 600 o000 80 0 40 0 200Binding Energy (eV)

Fig. 2. XPS wide-scan spectrum of Ti6AI4V substrates after soaking in a1.0 mol/I H3P04-1.5 wt.% HF solution for 20 min.

7507

(c)~

; : : i~ (b). - SU~ . ..s

(a)20 50 55 605 30 35 40

2 theta45

Fig. 3. XRD patterns of nacre coatings deposited in a nacre/ethanol suspensionwith or without the Hel additive on Ti6AI4V substrates: (a) Ti6AI4V substrates;(b) nacre coating without the Hel additive; and (c) nacre coating with the Heladditive. Main peaks: _, aragonite; A, Ti.

additive. Calcium carbonate has three forms, including calcite,vaterite, and aragonite. Its stable phase at atmospheric pressureis calcite, whereas the phase of the mineral in nacre is aragonitewith no other phases (JCPDS 76-0606), as shown in Fig. 3b.XRD pattern has the very sharp lines characteristic of a well-crystallized mineral. There are no obvious differences betweenFig. 3b and c, indicating that the addition of the HCI additive ina suspension does not change the crystalline phase of nacrecoatings.

Fig. 4 shows FTIR spectra of nacre coatings deposited byelectrophoresis technique with or without the HCI additive.Fig. 4a details further the structure of nacre powders in coatings.The nacre of C. jluminea is composed of 98.1 wt.% mineralphase and 1.9 wt.% organic component. There are characteristicpeaks of CaC03 in the aragonite form, corresponding to CO~- at1480 (V3 ) , 1080 (vd, 860 (V2 ) , 714 (V4 ) em-[, and Cr=O groupsof carbonate ions at 1790 em- [ [23]. Previous studies haveshown that the organic matrix of nacre contains many proteins,

4000 3500 3000 2500 2000 1500 1000 500Wavenumber (cm')

Fig. 4. FTIR spectra of nacre coatings deposited in a nacre/ethanol suspensionwith or without the Hel additive: (a) without the Hel additive; and (b) with thencr additive.


4/8


including fibrous proteins, proteoglycans and calcium bindingproteins, which perform a function similar to that of collagenpresent in bone, and tend to induce bone formation [24-26]. Thestrong IR bands at around 2920, 3430, and 2S20 em -[ areattributed to the C-H stretching modes, the OH and/or NHstretching modes, and the OH groups of carboxylic acid,respectively. However, the intense absorption bands in the rangeof 1660-1100 em - [ due to organic matrix components areoverlapped by the absorption band of carbonate ions in the V3region [26]. No obvious differences are observed between thenacre coatings deposited with and without the HCI additive. Thisresult is consistent with that of XRD patterns.3.2. Effect of the Hel additive on morphology of nacre coatings

Fig. S shows the SEM micrographs of nacre coatingsdeposited in a nacre/ethanol suspension without acid additives.A perfectly crack-free nacre coating is obtained by electrophor-esis technique, as shown in Fig. Sa. As we now knowbioceramic coatings by electrophoretic deposition are easy tocrack due to the drying shrinkage during drying and sintering

Fig. 5. SEM micrographs of nacre coatings deposited in a nacre/ethanolsuspension without acid additives: (a) lower magnification; (b) highermagnification.

stage [19]. Some researchers have solved this problem byOstwald ripening approach [18] or repeated deposition process[17]. In the present work, a crack-free coating is producedwithout any additional process. The possible reason may be thatthe presence of organic component reduces the surface energyof nacre powders, leading to dispersed particles and crack-freecoatings. At a higher magnification (Fig. Sb), it is revealed thatthe nacre powders in the range from 0.2 to 1 urn are stackedloosely together due to weak electrostatic bonding duringelectrophoretic deposition.

Fig. 6 shows the SEM micrographs of nacre coatingsdeposited by electrophoresis technique in a nacre/ethanolsuspension with the HCI additive. A uniform and crack-freenacre coating is observed in Fig. 6a with the average thicknessof about 30 urn (Fig. 7a). In addition, Fig. 6a shows that thecoating surface looks like glue, and the nacre powders areconnected together. The main reason is discussed according tothe dissolution-precipitation reaction, which occurs duringelectrophoretic deposition. After a O .S ml of 1.0 molll HCIsolution is added into a nacre/ethanol suspension, a dissolutionreaction takes place. The reactions are expressed as:

(1 )(2 )(3 )

Fig. 6c shows the microtopography of the nacre coating aftercalcium carbonate crystals on the nacre surface are dissolvedpartly. The nanofibers, composed of organic components andcalcium carbonate unreacted, are observed, which are inter-connected to form network structures rather than isolatednanofibers. The nacre powders surfaces are activated at the siteswhere the calcium ions are released [23].

Electrophoretic deposition is a two-step process: electro-phoresis and deposition [14]. Nacre powders with positivecharge move toward the cathode under the effect of an electricfield, and then deposit on the substrate surface (Fig. 8). At thesame time, other positive ions such as hydrogen ions (H+), cal-cium ions (Ca2+) move toward the cathode too. H+ is reduced atthe cathode surface to produce hydrogen gas; thus the con-centration of hydroxide ions increases, as shown in the followingreactions:

(4 )( S )

The hydroxide ions generated at the surface may react withCO2 in the suspension (Eq. (3)) and hydrogen carbonate ions(HCO_3)according to the reactions shown below:

(6 )(7 )

As the concentrations of the released Ca2+ and CO~- ionsbecome supersaturated with respect to calcium carbonate in thelocal suspension on the cathode surface, CaC03 crystals re-


5/8

YP Guo, Y Zhou / Surface & Coatings Technology 201 (2007) 7505-7512 7509

Fig. 6. SEM micrographs of nacre coatings deposited in a nacre/ethanol suspension with the Hel additive: (a) lower magnification; (b) higher magnification; (c)enlargement of box I in (b); (d) enlargement of box 2 in (b).

precipitate on the active sites of nacre powder surfaces, asshown:

Fig. 6d shows that CaC03 crystals (Eq. (8)) are arrangedalong the organic matrix of nacre, which behaves as a templatefor crystal formation by heteroepitaxial growth [27]. A previousstudy [28] has demonstrated that the ordered brick-and-mortararrangement of organic and inorganic layers is the most essentialstrength-and toughness-determining structural feature of nacre.

The negative ions such as hydroxide ions (OH-), chlorideions (Cl"), and carbonate ions (CO~-) move toward the anodeduring electrophoretic deposition. OH- and Cl" ions areoxidated at the anode surface to produce oxygen gas andchlorine gas, respectively, as shown:

(9 )(10)

In general, the dissolution-precipitation mechanism ofcarbonate calcium crystals comprises a complex sequence, asshown in Fig. 8. Firstly, carbonate calcium in nacre powders

(8 )

react with HC I to form Ca2+, HCO_3, and CO2, after a 0.5 mlHC I solution is added into a nacre nacre/ethanol suspension.Secondly, the positive ions (Ca2+, H+) move toward the cathodewithin an electric field, while the negative ions (OH-, Cl")move toward the anode. Thirdly, the increase of hydroxide ionstends to assist the formation of CO~- ions, as H+ ions arereduced at the cathode surface. Finally, the free calcium ionsbind the carbonate ions to form carbonate calcium andprecipitate it again on the active sites of nacre powder surfaceswhere the calcium ions are released.

Based on the dissolution-precipitation reaction, the forma-tion mechanism of the glue-like nacre coating in Fig. 6a can bedemonstrated. First, nacre is composed of calcium carbonatecrystallized in the form of aragonite on an organic matrixscaffold. The contents of the organic components on the nacrepowders surfaces increase, after calcium carbonate crystals aredissolved partly due to the addition of the HC I additive(Eq. (1)). The nacre powders are connected more densely thanthose without the HCI additive, since the organic componentsact as superglue [15]. Second, the more positive ions (Ca2+, H+)are adsorbed on the nacre powders in the suspension with theHC I additive than those without acid additives, since the


6/8


(b)3.0

2. 4

~ 1.8U

1.20

0.6 A ~.0

Ca

PI Ca\ J \2 3 4 S

E nerg y (K e V )Fig. 7. (a) Cross section of nacre coating deposited in a nacre/ethanol suspensionwith the HCI additive, and (b) EDX spectrum of the nacre coating layer.

dissolution reaction occurs in the suspension with the HCladditive. Moreover, no characteristic peaks corresponding toCl" appear in nacre coatings in Fig. 7b, indicating that fewnegative ions (Cl") are absorbed on the nacre powders duringelectrophoretic deposition. The increase of the positive ionsabsorbed on nacre powders makes electrostatic bondingbetween nacre powders and cathode (Ti6A14V substrate)strengthen within an electric field, leading to a good connectionamong nacre powders. Third, the interspaces among nacrepowders are filled partly with the recrystallized calciumcarbonate crystals due to the precipitation reaction (Eq. (8)).3.3. Effect of the H'Cl additive on deposition rate

Electrophoretic deposition of nacre is a colloidal processwhere nacre powders are deposited directly from a stable colloidsuspension within a direct current electric field (DC). Thedeposition yield of nacre powders is determined by electro-phoretic velocity (v). The electrophoretic velocity is related tothe applied voltage, charge, particle size and so on, as shown [9]:

v=QE/4nrl1 (11 )where Q, r, and 1] represent the charge, particle radius, andviscosity of the suspension, respectively, E is the potential of a

electric field. The variation of 1] can be neglected because thenacre powders concentration in the suspension is low. As aresult, the electrophoretic velocity mainly depends on theapplied voltage, the charge, and the particle size.

Fig. 9 shows the deposition yield of nacre powders as afunction of time at deposition voltage of90 V. Fig. 10 shows thedeposition yield of nacre powders as a function of potentialunder a constant deposition time of 120 s. According to Figs. 9and 10, it is worth noting that the deposition yield of nacrepowders in the suspension with the HCl additive exceeds that

Nacre/Ethanol Suspension0 0 0 000 0 00 0

0.5 miLO molll HC]

0 0 00 00 000 00 0CaCO -- > C02 . +Ca"+3 3CO~'+ H+ -7HCO; f-HCO;+ H+--;CO, +H2O

Anode Cathode; ; - . . , : : - - . . . . , . . . , . ~~< E - O o-

-- 0 Q.;. . . , . ~~"\ < E - O o- ~~< E - O fI7 ' - < : ~< E - O H ' - < :- - - 2C1- -2e -- > ci, t40W -4e --;0, i+2H,O

2H' +2e --; H, tco, + ow ....,HCO, I--HCO~+ OW --; CO;- + H,oCO1- + Ca1+--; CaCO J .3 -)

ON acre powders ci+, H+

o cot,OH', cr. HCO;o o, H2, C12, CO2

o CaC03 precipitated againFig. 8. Dissolution-precipitation mechanism mode of carbonate calciumcrystals in a nacre/ethanol suspension with the HCI additive during electro-phoretic deposition.


7/8

YP Guo, Y Zhou / Surface & Coatings Technology 201 (2007) 7505-7512

without the HCI additive. The main reason is that the addition ofthe HCI additive obviously increases the current density,reached at about 4.44 mA/cm2. However, it is too small to bedetected without the HCI additive. The increase of currentdensity tends to improve electrophoretic velocity of nacrepowders. In addition, another reason cannot be excluded. Thepositive ions such as Ca2+, H+ are released from the nacrepowders (Eq. (1)) and HCI additive, respectively, after the HCIadditive is added into a nacre/ethanol suspension. The chargesof nacre powders increase as the positive ions are adsorbed ontheir surfaces; thus the more deposition yield is obtained(Eq. (11)). The result is proved further by SEM micrographs ofnacre coatings. The positive ions absorbed on nacre powderssurfaces make bigger particles with 4 urn in diameter deposit ontitanium alloys, as shown in Fig. 6b.

Fig. 9 shows that the deposition yield increases, as expected,with deposition time in both suspensions. The slopes of twocurves are steeper at the beginning, while they decrease withtime. The reasons can be explained by the following tworeasons. First, voltage drop in deposit is proportional to depositresistivity, which, in turn, increases with the increase of depositthickness [29]. The deposition rate decreases with depositiontime due to the increase in voltage drop in the deposited layer.Second, the smaller particles in a suspension reach the higherelectrophoretic velocity than the bigger ones (Eq. (11)). Thesuspension used in this work has a wide distribution of particlesizes. The presence of many smaller particles contributed toacquire larger deposition rate, but the deposition rate decreaseswith time due to the decrease of smaller particles. Fig. 10 showsthat the relationship between the deposition yield and potentialis a roughly linear increase. The main reason is the linearrelationship between electrophoretic velocity and potential, asshown in Eq. (11).

The addition of acid additives creates an acidic environmentin the suspension to induce positive charges to the powders.Besides the HCI additive, other acids such as nitric acid(HN03) and acetic acid (CH3COOH) [15] can improve the

[815

M 126(Jbh3 9'0]1 6> -'

3

0 0 30 60 90Time (S)

120 150 180

Fig. 9. Deposition yield of nacre powders as a function of deposition time in anacre/ethanol suspension with or without acid additives: (a) with the HCIadditive; (b) with the HN03 additive; (c) without acid additives. Conditions:solid/solvent=S gil, poreruial=vu V/cm.

7511

24

20e . . . . . . 16Eo- -0g 12'0


8/8


AcknowledgementsThe authors thank the financial support from the Post-Doctor

Foundation of China (20060390786) and Post-Doctor Founda-tion of Heilongjiang.References[I] A. Sellinger, P.M. Weiss, A. Nguyen, Y.F. Lu, R.A. Assink, WL. Gong,

C.J. Brinker, Nature 394 (1998) 256.[2] M. Lamghari, M.J. Almeida, S. Berland, H. Huet, A. Laurent, C. Milet, E.

Lopez, Bone 25 (1999) 91S.[3] H.H. Liao, H. Mutvei, M. Sjostrom, L. Hammarstrom, LG. Li,

Biomaterials 21 (2000) 457.[4] T. Kokubo, H.M. Kim, M. Kawashita, Biomaterials 24 (2003) 2161.[5] M.H. Fathi, M. Salehi, A. Saatchi, V. Mortazavi, S.B. Moosavi,

Dent. Mater. 19 (2003) 188.[6] X.X. Wang, L. Xie, R.Z. Wang, Biomaterials 26 (2005) 6229.[7] J.L. Sui, M.S. Li, Y.P. Lu, Y.Q. Bai, Surf. Coat. Techno!. 190 (2005) 287.[8] T. Onoki, K. Hosoi, T. Hashida, Scripta Mater. 52 (2005) 767.[9] P. Mondragon-Cortez, G. Vargas-Gutierrez, Adv. Eng. Mater. 5 (2003)

812.[10] H.F. Zhou, X.X. Wang, R.Z. Wang, Key Eng. Mater. 309-311 (2006) 747.[II] H.M. Kim, F. Miyaji, T. Kokubo, T. Nakamura, L Biomed. Mater. Res. 32

(1996) 409.[12] K. Hosoi, T. Hashida, H. Takahashi, N. Yamasaki, T. Korenaga,

J. Am. Ceram. Soc. 79 (1996) 2771.

[13] X. Nie, A. Leyland, A. Matthews, Surf. Coat. Techno!. 125 (2000) 407.[14] A.R. Boccaccini, L Zhitomirsky, Curro Opin. Solid State Mater. Sci. 6

(2002) 251.[IS] R. Wang, J. Mater. Sci. 39 (2004) 4961.[16] X. Nie, A. Leyland, A. Matthews, J.C. Jiang, E.L Meletis, J. Biomed.

Mater. Res. 57 (2001) 612.[17] C. Wang, J. Ma, W Cheng, R.F. Zhang, Mater. Lett. 57 (2002) 99.[18] M. Wei, A.J. Ruys, B.K. Milthorpe, C.C. Sorrell, J. Biomed. Mater. Res.

45 (1999) II.[19] L.A. de Sena, M.C. de Andrade, A.M. Rossi, G.D. Soares, J. Biomed.

Mater. Res. 60 (2002) I.[20] S.H. Oh, R.R. Finones, C. Daraio, L.H. Chen, S.H. Jin, Biomaterials 26

(2005) 4938.[21] M. Takeuchi, Y. Abe, Y.Yoshida, Y. Nakayama, M. Okazaki , Y. Akagawa,

Biomaterials 24 (2003) 1821.[22] R.Z. Legeros, R.G. Craig, J. Bone Miner. Res. 8 (1993) S583.[23] M. Ni, B.D. Ratner, Biomaterials 24 (2003) 4323.[24] Y.W Kim, J.J. Kim, Y.H. Kim, J.Y. Rho, Biomaterials 23 (2002) 2089.[25] E. Lopez, B. Vidal, S. Berland, S. Camprasse, G. Camparasse, C. Silve,

Tissue Cell. 24 (1992) 667.[26] J. Balmain, B. Hannoyer, E. Lopez, J. Biomed. Mater. Res. App!.

Biomater. 48 (1999) 749.[27] M. Rousseau, E. Lopez, A. Coute, G. Mascarel, D.C. Smith, R. Naslain,

X. Bourrat, Key Eng. Mater. 254-256 (2004) 1009.[28] Z.Y. Tang, N.A. Kotov, S. Magonov, B. Ozturk, Nat. Mater. 2 (2003) 413.[29] L Zhitomirsky, Mater. Lett . 42 (2000) 262.

Documents

Nacre Coatings Deposited by Electrophoresis on Ti6Al4V