Apatite films produced by electrodeposition: characterization by TEM and AFM

Manso, M.; Jiménez, Carmen; Morant, Carmen; Herrero, Pilar; Martı́nez-Duart, J.M.

doi:10.1002/sia.1153

Cited by 26 publications

(34 citation statements)

References 30 publications

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“…12) However, this method results in an increasing pH at the interface between Ti and electrolyte due to the electron incorporation to form OH -ions and H 2 through water reduction. The H 2 gas evolution at the interface leads to a heterogeneous coating.…”

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confidence: 99%

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Coating of hydroxyapatite films on titanium substrates by electrodeposition under pulse current

Hayakawa

Kawashita

Takaoaka

2008

J. Ceram. Soc. Japan

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Titanium (Ti) metal substrates were etched in sulfuric acid (H 2 SO 4 ) with concentrations of 25, 50, 75 and 97 at 60°C for 30 min. Hydroxyapatite (HA) films were deposited onto unetched and etched substrates by an electrodeposition method under a pulse current. The electrolyte was metastable calcium phosphate solution that had 1.5 times the ion concentrations of human body fluid, but did not contain magnesium ion at 36.5°C. Deposition times were 90 min. We used the average current density of 0.01 A/cm 2 and ON time equal to OFF time of 15 s. In the electrodeposition, hydrogen was incorporated into the surface of the Ti substrates to form titanium hydride (TiH 2 ) on the substrate surfaces. After the electrodeposition, all specimens were heated at 600°C for 60 min. The adhesion between apatite and substrates were greatly improved by the heat treatment for the substrates etched in 50 and 75 H 2 SO 4 . It is considered that in these specimens the anchoring effect due to the microstructural roughness formed by etching was enhanced by the shrinking of HA crystals during the heat treatment.

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Section: )-11)mentioning

confidence: 99%

“…The H 2 gas evolution at the interface leads to a heterogeneous coating. 12) In addition, adhesive strength between the apatite and substrate is often low. Therefore, in order to solve the above problems, new approaches are needed in the electrodeposition method.…”

Section: )-11)mentioning

confidence: 99%

Coating of hydroxyapatite films on titanium substrates by electrodeposition under pulse current

Hayakawa

Kawashita

Takaoaka

2008

J. Ceram. Soc. Japan

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“…[8] Hence, ELD of HA coating has attracted considerable attention in recent years. [9][10][11] However, the previous researches have all focused on the deposition on pure Ti and its alloys. It is generally believed that the reduction of H 2 O causes rise of local pH of the electrolyte in the vicinity of the cathode titanium surface and, consequently, results in Ti-OH layer formation.…”

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Electrolytic Deposition of Hydroxyapatite Coating on CoNiCrMo Substrates

2010

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Cobalt-based alloys have long been used as prosthetic implant in orthopedic surgery. [1,2] However, the lack of bioactivity and the consequent slow osteointegration (typically taking 3-6 months) limits their application in clinics. Hydroxyapatite (HA, Ca 10 (PO 4 ) 6 (OH) 2 ) is the mineral component of natural bone, and shows excellent osteointegration when used as implant material in orthopedic fields. In order to achieve bioactivity for load-bearing metallic implants, HA coatings have been introduced recently due to their degradable property.To date, various techniques, such as plasma spraying, [3] laser ablation, [4] biomimetic, [5] and electrolytic deposition (ELD), [6,7] have been employed in the preparation of HA coatings. Among them, ELD possesses various advantages in the following aspects: (1) being conducted in mild aqueous solution;(2) being suitable to complex or porous surface structures; (3) with high efficiency and low cost; (4) the obtained coating being porous and thus degradable in vivo. [8] Hence, ELD of HA coating has attracted considerable attention in recent years. [9][10][11] However, the previous researches have all focused on the deposition on pure Ti and its alloys. It is generally believed that the reduction of H 2 O causes rise of local pH of the electrolyte in the vicinity of the cathode titanium surface and, consequently, results in Ti-OH layer formation. Calcium ions are incorporated in the hydrated Ti-OH layer. The positively charged Ca 2þ may act as nucleation sites by attaching to negatively charged (PO 4 ) 3 to form Ca-P crystals. During this process, the Ti-OH layer (including physisorbed hydroxyls and chemisorbed OH hydroxyl groups) is considered to play a role in the nucleation of apatite by a number of researchers. [7,12,13] In the present work, we explored the possibility of depositing HA coating on a CoCrMoNi alloy substrate by the ELD technique. We also constructed a unique experiment to reveal the importance of the local pH to the crystallization and investigate whether the substrate surface property is vital to the nucleation of apatite during ELD process. ExperimentalA sheet (10 mm Â 10 mm Â 1 mm) made of wrought 35Co-35Ni-20Cr-10Mo alloy (ASTM F562) was used as cathode. Prior to ELD, the cathode was mechanically ground on SiC papers from P120 to P800 grit before polishing, cleaned ultrasonically in acetone, rinsed with DI water, and dried.ELD was carried out in a three-electrode macrocell. During the process of ELD, an accompanying uncharged specimen (including CoNiCrMo alloy, Ti plate, and nonconducting polyethylene plate and glass) was placed parallel to the cathodic CoCrMoNi specimen with a spacing of 1 mm. The bath contained 0.6 mM Ca(NO 3 ) 2 Á 4H 2 O and 0.36 mM NH 4 H 2 PO 4 with Ca/P ratio being 1.67 in DI water. The pH was adjusted to 6.0 at room temperature by ammonia additions. A Pt foil and an Ag/AgCl electrode were used as counterelectrode (anode) and reference electrode, respectively. The ELD was conducted with a CHI1140 (USA) potentionstat/galvanostat ...

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“…Compared with regular multicomponent coatings, FGCs can effectively reduce the discontinuity of the thermal-expansion coefficients between the materials, and minimize the residual stresses in the coatings. Then, the useful life of the coatings can be improved.So far, various techniques, such as plasma spraying, [7,8] magnetron sputtering, [9,10] laser ablation, [11,12] sol-gel, [13,14] electrolytic deposition [15][16][17] and biomimetic strategies, [18] have been employed to prepare HA coatings. Of these, radiofrequency (RF) magnetron sputtering has the advantages of high deposition rate, relatively low sputtering temperature, uniform coating and high binding strength.…”

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Preparation of Novel Hydroxyapatite/Yttria‐Stabilized‐Zirconia Gradient Coatings by Magnetron Sputtering

Lin

Zhao

2010

Adv Eng Mater

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Recently, interest in the preparation of hydroxyapatite (HA) (Ca 10 (PO 4 ) 6 (OH) 2 ) coatings on biomedical titanium and its alloy (Ti6Al4V) has evolved in the research of dental materials and artificial bone implants. [1][2][3][4][5][6] However, as the thermal expansion coefficient of Ti6Al4V is $8.53-9.5 Â 10 À6 K À1 while that of HA is about 15 Â 10 À6 K À1 , the thermal-expansion coefficients between the two materials could lead to excessive residual stresses in the coatings and consequent lay great limits to the repair of bone defects. One way to overcome these problems is the use of functionally gradient coatings (FGCs). In an FGC, an intermediate layer with a gradual compositional variation is applied between the top coating and the substrate. Compared with regular multicomponent coatings, FGCs can effectively reduce the discontinuity of the thermal-expansion coefficients between the materials, and minimize the residual stresses in the coatings. Then, the useful life of the coatings can be improved.So far, various techniques, such as plasma spraying, [7,8] magnetron sputtering, [9,10] laser ablation, [11,12] sol-gel, [13,14] electrolytic deposition [15][16][17] and biomimetic strategies, [18] have been employed to prepare HA coatings. Of these, radiofrequency (RF) magnetron sputtering has the advantages of high deposition rate, relatively low sputtering temperature, uniform coating and high binding strength. Therefore, RF magnetron sputtering of HA coatings has attracted considerable attention in recent years. Ding et al. [19] reported that a monolithic-HA coating on Ti6Al4V prepared by RF magnetron sputtering has a bond strength of 59.9 MPa, which is believed to be greater than that produced by any other coating techniques. However, the monolithic-HA coating was a loosely bonded, granular-shaped structure and had a number of surface cracks. They developed a new multilayered coating by alternately depositing Ti and HA layers on Ti6Al4V substrates using RF magnetron sputtering to improve the interface properties between the coating and the substrate. [9] The multilayered coating had a higher binding strength and better immersion behavior in simulated body fluid (SBF) than the monolithic-HA coating.Zirconia (ZrO 2 ), and especially yttria-stabilized zirconia (YSZ), with its favorable biocompatibility and a thermal expansion coefficient of about 8.0 Â 10 À6 K À1 , has the attributes of high strength and stress-induced phase-transformation toughening, and has been used to reinforce hydroxyapatite coatings and to improve the bond strength of HA coatings. [20] Khor et al. [21] developed HA/YSZ/Ti6Al4V composite coatings that have superior mechanical properties to conventional plasma-sprayed HA coatings. To the best of our knowledge, reports on the preparation of gradient HA/YSZ coatings on Ti6Al4V by RF magnetron sputtering are scarce. The objective of this work is to explore the possibility of preparing gradient HA/YSZ coatings on Ti6Al4V by RF magnetron sputtering and to examine their immersion behavior afte...

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Apatite films produced by electrodeposition: characterization by TEM and AFM

Cited by 26 publications

References 30 publications

Coating of hydroxyapatite films on titanium substrates by electrodeposition under pulse current

Coating of hydroxyapatite films on titanium substrates by electrodeposition under pulse current

Electrolytic Deposition of Hydroxyapatite Coating on CoNiCrMo Substrates

Preparation of Novel Hydroxyapatite/Yttria‐Stabilized‐Zirconia Gradient Coatings by Magnetron Sputtering

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