Effects of Spraying Parameters on Phase Formation and Distribution in Plasma-Sprayed Hydroxyapatite Coatings

2000 ◽  
Author(s):  
L. Sun ◽  
C.C. Berndt ◽  
R.S. Lima ◽  
A. Kucuk ◽  
K.A. Khor
Keyword(s):  
Opposite Effect ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
Tetracalcium Phosphate ◽  
X Ray ◽  
Impurity Phases ◽  
Hydroxyapatite Coatings ◽  
Spraying Parameters ◽  
Plasma Sprayed ◽  
Spray Dried

Abstract Calcined spray-dried hydroxyapatite (Ca10(PO4)(OH)6; i.e., HA) powders were atmospherically plasma sprayed (APS) using various process parameters. The resulting phases within the coating surface and the interface between the coating and the substrate were analyzed using X-ray diffraction (XRD) methods. This XRD revealed the presence of both amorphous (i.e., amorphous calcium phosphate: ACP) and crystalline phases. The crystalline phases included both HA and some impurity phases from the decomposition of HA, such as tricalcium phosphate (α-TCP and β-TCP), tetracalcium phosphate (TTCP) and calcium oxide (CaO). The crystallinity of HA decreased with increasing spray power and stand-off distance (SOD). The percentage of all impurity phases increased with the spray power. The percentage of both TCP and TTCP decreased with the SOD while the CaO percentage increased. In addition, the percentage of ACP and CaO were higher in the interface than at the surface of the coating while the percentage of TCP and TTCP exhibited the opposite effect.

Influence of Sterilization with γ-Irradiation in the Degradation of Plasma Sprayed Hydroxyapatite Coatings

2006 ◽  
Vol 514-516 ◽  
pp. 1054-1058 ◽  
Author(s):  
Tânia Costa ◽  
Ana Paula Serro ◽  
Eduardo Pires ◽  
Rogerio Colaço
Keyword(s):  
Mechanical Behaviour ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Γ Irradiation ◽  
Water Contact ◽  
X Ray ◽  
Angle Measurements ◽  
Hydroxyapatite Coatings ◽  
Plasma Sprayed ◽  
Irradiation Process

The influence of sterilization with γ-irradiation in the properties of plasma sprayed hydroxyapatite (HAp) coatings used for medical implants is investigated in this work. HAp coatings were applied on titanium alloy substrates by plasma spraying and then submitted to 1 and 10 cycles of sterilization with γ-irradiation. As-applied HAp coatings were used as control samples. Afterwards, the modifications on the samples, induced by the irradiation process, were evaluated by X-ray diffraction and X-ray photoelectron spectroscopy (XPS). Water contact angle measurements as well as adhesion tests were also carried out in order to evaluate the influence of the irradiation process on the wettability and mechanical behaviour of the HAp coatings. No microstructural modifications were detected by X-ray diffraction after sterilization. However, the results show that sterilization with γ-irradiation originates modifications of the surface of HAp, as detected by a change of color of the coatings and by the XPS analysis. Nevertheless, these modifications do not result in significant changes in the wettability and mechanical behaviour of the HAp coatings.

Enhancing the Bonding Strength of Plasma-Sprayed HA Coating on Pure Ti

2007 ◽  
Vol 561-565 ◽  
pp. 1553-1556 ◽  
Author(s):  
Sen Yang ◽  
Hau Chung Man
Keyword(s):  
Calcium Phosphate ◽  
Calcium Oxide ◽  
Tricalcium Phosphate ◽  
X Ray Diffraction ◽  
Tetracalcium Phosphate ◽  
X Ray ◽  
Gas Nitriding ◽  
Ha Coating ◽  
Scaffold Structure ◽  
Plasma Sprayed

A layer of bioceramic HA was coated on laser gas nitrided and grit-blasted pure Ti substrates using plasma-spraying technique, respectively. X-ray diffraction analysis showed that the microstructures of the coating were mainly composed of HA, amorphous calcium phosphate and some minute phases of tricalcium phosphate, tetracalcium phosphate and calcium oxide. The experimental results showed that the 3-D TiN dendritic scaffold structure produced on the surface of pure Ti using laser gas nitriding technique in advance could anchor the HA coating and improved the interfacial adherence significantly as compared with those on the grit blasted surfaces.

Studies on diffusion maximum in x-ray diffraction patterns of plasma-sprayed hydroxyapatite coatings

1998 ◽  
Vol 40 (3) ◽  
pp. 407-413 ◽  
Author(s):  
Weidong Tong ◽  
Zongjian Yang ◽  
Xingdong Zhang ◽  
Aiping Yang ◽  
Jiaming Feng ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Hydroxyapatite Coatings ◽  
Diffraction Patterns ◽  
Plasma Sprayed

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

Sign in / Sign up

Export Citation Format

Share Document