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

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.

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Practice for X-ray Diffraction Determination of Phase Content of Plasma-Sprayed Hydroxyapatite Coatings

10.1520/f2024-10 ◽

2010 ◽

Author(s):

Keyword(s):

Phase Content ◽

X Ray Diffraction ◽

X Ray ◽

Hydroxyapatite Coatings ◽

Diffraction Determination ◽

Plasma Sprayed

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Characterization of Plasma Sprayed Yittria Stabilized Zirconia (8 wt %) Hydroxyapatite Coatings

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.493-494.535 ◽

2011 ◽

Vol 493-494 ◽

pp. 535-538

Author(s):

O. Anzabi ◽

M.M. Aydin ◽

L.S. Ozyegin ◽

F.N. Oktar ◽

Kārlis A. Gross ◽

...

Keyword(s):

Titanium Oxide ◽

Pure Titanium ◽

X Ray Diffraction ◽

Stabilized Zirconia ◽

X Ray ◽

Bond Coatings ◽

Bond Coating ◽

Bond Layer ◽

Diffraction Patterns ◽

Plasma Sprayed

Splitting problems at HA-coated implants are generally due to biological reasons. Bond-coatings were used to prevent the splitting problem of zirconia ceramics; this method can be widely seen in industrial applications. Two main groups were used; the first group consisted of spraying a bond layer of titania onto commercially pure titanium. This followed by a spray of HA with 5, 10 and 15 % zirconia (8 % yttria doped) as main layer onto the first bond-coating. For the second group, the samples were coated without bond-coating. Firstly, X-ray diffraction patterns of the starting powders were taken. Then x-ray diffraction patterns of the plasma sprayed samples were taken. In literature, it was seen that 20 % zirconia was sufficient for the transformation into a monoclinic structure for the bond-coated samples. For this study it was found that 10 % zirconia was sufficient to transform to the same structure of the desired crystalline phase transformation. The coating kept its crystal structure and relatively small amount of amorphous transformation was detected. A similar structure was produced using less zirconia. It was thought that the use of titanium-oxide bond-coating layer would play an important role as a third variable in the results. To further investigate these phenomena, more detailed researches must be conducted with using titanium-oxide yittria stabilized zirconia (8 wt %) hydroxyapatite bond-coatings with HA main coatings.

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

Thermal Spray 2000: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc2000p0803 ◽

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.

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A synchrotron X-ray diffraction deconvolution method for the measurement of residual stress in thermal barrier coatings as a function of depth

Journal of Applied Crystallography ◽

10.1107/s1600576716013935 ◽

2016 ◽

Vol 49 (6) ◽

pp. 1904-1911 ◽

Cited By ~ 10

Author(s):

C. Li ◽

S. D. M. Jacques ◽

Y. Chen ◽

D. Daisenberger ◽

P. Xiao ◽

...

Keyword(s):

Residual Stress ◽

Thermal Barrier ◽

Stress Profile ◽

Air Plasma ◽

X Ray Diffraction ◽

X Ray ◽

Barrier Coating ◽

Average Residual ◽

Diffraction Patterns ◽

Plasma Sprayed

The average residual stress distribution as a function of depth in an air plasma-sprayed yttria stabilized zirconia top coat used in thermal barrier coating (TBC) systems was measured using synchrotron radiation X-ray diffraction in reflection geometry on station I15 at Diamond Light Source, UK, employing a series of incidence angles. The stress values were calculated from data deconvoluted from diffraction patterns collected at increasing depths. The stress was found to be compressive through the thickness of the TBC and a fluctuation in the trend of the stress profile was indicated in some samples. Typically this fluctuation was observed to increase from the surface to the middle of the coating, decrease a little and then increase again towards the interface. The stress at the interface region was observed to be around 300 MPa, which agrees well with the reported values. The trend of the observed residual stress was found to be related to the crack distribution in the samples, in particular a large crack propagating from the middle of the coating. The method shows promise for the development of a nondestructive test for as-manufactured samples.

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