High temperature in-situ XRD of plasma sprayed HA coatings

Citation
Swk. Kweh et al., High temperature in-situ XRD of plasma sprayed HA coatings, BIOMATERIAL, 23(2), 2002, pp. 381-387
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Multidisciplinary
Journal title
BIOMATERIALS
ISSN journal
0142-9612 → ACNP
Volume
23
Issue
2
Year of publication
2002
Pages
381 - 387
Database
ISI
SICI code
0142-9612(200201)23:2<381:HTIXOP>2.0.ZU;2-E
Abstract
The control of phase transformations in plasma sprayed hydroxyapatite (HA) coatings are critical to the clinical performance of the material. This pap er reports the use of high temperature X-ray diffraction (HT-XRD) to study, in-situ, the phase transformations occurring in plasma sprayed HA coatings . The coatings were prepared using different spray power levels (net plasma power of 12 and 15 kW and different starting powder size ranges (20-45, 45 -75 mum). The temperature range employed was room temperature ( similar to 26 degreesC) to 900 degreesC in normal atmosphere and pressure. High temper ature differential scanning calorimetry (DSC) was also employed to investig ate and determine the precise onset temperature of phase transformations du ring the recrystallization process. Results showed that actual onset of the rmal degradation in the coating into other metastable phases like TTCP, bet a -TCP and CaO occurred at 638 degreesC. The aforementioned phase transitio ns were independent of the selected spraying parameters. The degree of melt ing and thermal dissociation of HA actually determines the amount of calciu m phosphate phases that are formed. A high power level of 15 kW produced a greater degree of melting, resulting in more CaO, TTCP and beta -TCP being formed as a result. (C) 2001 Elsevier Science Ltd. All rights reserved.