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Phase transformation of plasma-sprayed hydroxyapatite coating with preferred crystalline orientation

Paper ID Volume ID Publish Year Pages File Format Full-Text
10859 705 2007 9 PDF Available
Title
Phase transformation of plasma-sprayed hydroxyapatite coating with preferred crystalline orientation
Abstract

Highly oriented hydroxyapatite coatings (HACs) were obtained on titanium substrates through a radio-frequency thermal plasma spraying (TPS) method. XRD patterns showed that the HACs had crystallites with [0 0 l] preferred orientation vertical to the coating's surface. XRD results also indicated that tetracalcium phosphate crystallites in the as-sprayed HAC were oriented in the (1 0 0) direction. XRD peaks corresponding to tetracalcium phosphate, tricalcium phosphate and calcium oxide were absent after heat and hydrothermal treatment. The orientation degree of the HAC was influenced little by such post-heat treatments. Considering the crystallographic relationship between the tetracalcium phosphate in the as-sprayed HAC and the HA crystallites formed in the heat-treated HAC, these XRD results indicate that the tetracalcium phosphate in the as-prepared coatings transformed topotaxially into HA during the post-heat treatment. TEM and SEM analyses of the highly oriented HAC were conducted. The characteristic lamellar structure of TPS deposits was observed in cross-sections of the HAC. A prismatic texture was also observed in magnified SEM images. TEM observation showed that 200–800-nm-wide prismatic crystallites were formed in HA splats, and their longitudinal axis was oriented vertically to the coating's surface. SAD patterns showed that the longitudinal axis of the prismatic crystallites corresponded to the [0 0 1] zone axis of the HA crystal.

Keywords
Hydroxyapatite; Plasma spraying; Crystal orientation; Crystallization; Phase transformation; Topotaxy
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Phase transformation of plasma-sprayed hydroxyapatite coating with preferred crystalline orientation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 28, Issue 19, July 2007, Pages 2923–2931
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us