Apatite/titanium composite coatings on titanium or titanium alloy by RF plasma-spraying process

Preparation and characterization of hydroxyapatite/titania composite coating on NiTi alloy by electrochemical deposition

“…Hence HAP has been widely used as a coating material for dental and orthopedic implants for many years [9][10][11]. Nevertheless it has been asserted that the interfacial adhesion is relatively weak between HAP coating and titanium alloy [12]. Titania (TiO 2 ) has attracted considerable attention as a bond coat due to its good corrosion resistance and biocompatibility, furthermore it can enhance the bonding strength between HAP and substrate [13][14][15][16].…”

Production and characterization of plasma-sprayed TiO2–hydroxyapatite functionally graded coatings

“…3 However, atmospheric plasma spraying is nowadays the most commonly used method in the industrial practice. 4 Plasma spraying is widely adopted to obtain HAp coatings onto titanium/titanium alloy implants since it is a well established and cost-effective surface treatment process, 2 nevertheless it has been asserted that the adhesiveness of HAp coatings is relatively weak and decreases in the case of thick coatings, 5 probably due to the mismatch in the coefficients of thermal expansion of HAp and titanium (11.5 × 10 −6 K −1 and 8.9 × 10 −6 K −1 , respectively). 6 In order to solve this problem, Khor et al proposed to create a promising HAp/titanium alloy graded coating.…”

Effects of plasma gas composition on bond strength of hydroxyapatite/titanium composite coatings prepared by rf-plasma spraying

“…4) were formed by thermal decomposition of the HA powder in the plasma, as reported in previous studies. [1][2][3][4]7,9,19 Reactions between HA and Ti particles contacting each other in the plasma flame might form some titanium-calcium compounds. However, no clear peaks corresponding to such titanium-calcium compounds were observed in the XRD patterns of our HA/Ti composite coatings.…”

“…Our technique for preparing the HA/Ti composite coatings is based on precise control of the starting material's composition using two microfeeders which make it possible to feed the HA and Ti powders at an accurate rate. 8,9 The starting material's composition was regulated so as to change the composition of the coating gradually from Ti-rich at the bottom to HA-rich at the top. HA powder (average particle size = 80 m, Pentax) and Ti powder (average particle size = 68 ± 15 m, 99.9%, Rare Metallic Co., Ltd., Japan) were used as raw materials.…”

“…7 Recently, we have developed a gradual composite coating method employing rf-TPS that provides strong adhesion between HA coatings and titanium (Ti) substrates. 8,9 Moreover, we have reported that the in situ nitriding of Ti particles by reactive-plasma spraying (RPS), a variation of plasma spraying, improves the bond strength of HA/Ti composite coatings. 10,11 During RPS, plasma-enhanced reactions between Ti particles and the reactive gaseous species present in the plasma flame produce various in situ synthesized phases on the surface of the Ti particles.…”