Microstructural characterisation and stress determination in as-plasma sprayed and incubated bioconductive hydroxyapatite coatings

Topić, M.; Ntsoane, T.P.; Heimann, Robert B.

doi:10.1016/j.surfcoat.2006.08.139

Cited by 24 publications

(13 citation statements)

References 41 publications

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“…Morphology of apatite crystals, observed after 28 days of soaking (Fig. 3), was similar to the typical "cauliflower" morphology of bone-like apatite layer previously reported for bioactive surfaces in vitro [4,34]. The largest agglomerates of "cauliflower-like" apatite precipitates were observed on the surface of cement C. It may be explained by the fact that materials containing resorbable calcium sulfate possessed less stable surface and could not provide firm substratum for apatite layer formation.…”

Section: Bioactivity Of Cement Type Bone Substitutessupporting

confidence: 82%

Bioactivity of cement type bone substitutes

Siek¹,

Czechowska²,

Mróz³

et al. 2013

Bulletin of the Polish Academy of Sciences: Technical Sciences

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In vitro chemical stability and bioactivity of three different cement type bone substitutes were determined by incubating cement samples in the simulated body fluid (SBF) for 7 and 28 days. Morphology of sample surfaces has been studied using scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectroscopy (EDS) and by atomic force microscopy (AFM). The diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS) was applied as a supplementary method. The development of bone-like apatite layers on the surface depended on their initial phase composition. Obtained cements showed good surgical handiness, high bioactive potential and were chemically stable. They seem to be promising materials for bone substitution.

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Section: Bioactivity Of Cement Type Bone Substitutessupporting

confidence: 82%

Bioactivity of cement type bone substitutes

Siek¹,

Czechowska²,

Mróz³

et al. 2013

Bulletin of the Polish Academy of Sciences: Technical Sciences

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“…In addition, this thin layer provides a low-energy fracture path that may lead to coating delamination in the presence of tensile residual stresses [21]. However, the transformation of ACP to crystalline calcium phosphate phases during in vitro contact with simulated body fluid and in vivo contact with biofluid, respectively will lead to stress relaxation as observed by Heimann et al [54] and Topić et al [53], and thus, reduces the risk of coating failure by delamination. Figure 5 shows the lattice strain of hydroxylapatite coatings deposited by plasma spraying on Ti6Al4V substrates measured as a function of sin 2 ψ, where ψ is the tilt angle towards the X-ray beam.…”

Section: Residual Stressesmentioning

confidence: 98%

“…When the molten particles strike the cold substrate, they are rapidly quenched whereby their contraction is constrained by tight adherence to the rough and rigid substrate. This leads to accumulation of high levels of tensile stresses both within the coating and at the coating-to-substrate interface, commonly referred to as "quenching stresses" [53]. The first layer adjacent to the interface, found to consist of amorphous calcium phosphate (ACP) [18] (see Figure 3B), will crucially control the occurrence of residual stresses in terms of magnitude as well as sign.…”

Section: Residual Stressesmentioning

confidence: 99%

Osseoconductive and Corrosion-Inhibiting Plasma-Sprayed Calcium Phosphate Coatings for Metallic Medical Implants

Heimann

2017

Metals

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During the last several decades, research into bioceramic coatings for medical implants has emerged as a hot topic among materials scientists and clinical practitioners alike. In particular, today, calcium phosphate-based bioceramic materials are ubiquitously used in clinical applications to coat the stems of metallic endoprosthetic hips as well as the surfaces of dental root implants. Such implants frequently consist of titanium alloys, CoCrMo alloy, or austenitic surgical stainless steels, and aim at replacing lost body parts or restoring functions to diseased or damaged tissues of the human body. In addition, besides such inherently corrosion-resistant metals, increasingly, biodegradable metals such as magnesium alloys are being researched for osseosynthetic devices and coronary stents both of which are intended to remain in the human body for only a short time. Biocompatible coatings provide not only vital biological functions by supporting osseoconductivity but may serve also to protect the metallic parts of implants from corrosion in the aggressive metabolic environment. Moreover, the essential properties of hydroxylapatite-based bioceramic coatings including their in vitro alteration in contact with simulated body fluids will be addressed in this current review paper. In addition, a paradigmatic shift is suggested towards the development of transition metal-substituted calcium hexa-orthophosphates with the NaSiCON (Na superionic conductor) structure to be used for implant coatings with superior degradation resistance in the corrosive body environment and with pronounced ionic conductivity that might be utilized in novel devices for electrical bone growth stimulation.

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“…In such cases, the material is applied as a coating on metallic substrates such as Ti, Ti alloys and CoCrMo, where the excellent mechanical properties of the metal are combined with the osseoconductive ability of the coating [4]. With the plethora of coating techniques available for deposition [5], thermal spray remains the method of choice on industrial scale [6]. It is known that the interaction of the high temperature droplets formed in the plasma, and subsequent rapid cooling on interaction with the cold substrates, leads to thermal decomposition.…”

Section: Introductionmentioning

confidence: 99%

In-vitro Investigation of Air Plasma-Sprayed Hydroxyapatite Coatings by Diffraction Techniques

Venter

Heimann

Topić

et al. 2016

Residual Stresses 2016

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Abstract. The influence exposure to simulated body fluid (SBF) has on plasma-sprayed hydroxyapatite (HAp) coatings of medical-grade Ti6Al4V rods was investigated by quantifying the depth dependence of the phase composition and residual stress through the coating thickness using diffraction techniques. Chemical phase identification showed HAp existing together with its thermal decomposition products, tetra-calcium phosphate (TTCP), tri-calcium phosphate (TCP) and calcium oxide. With depth, the HAp content decreases with a corresponding increase in TTCP. The near surface stress condition comprised ~50 ± 10 MPa hoop stress with the radial stress being close to zero. With depth the hoop stress decreases linearly to ~-50 ± 25 MPa at the substrate interface, whilst the radial stress increases with depth. Upon exposure to SBF, the coating composition reveals an increase in HAp from ~80.0 ± 0.5 to ~86.0 ± 0.5 wt%, accompanied by a decrease of TTCP from ~10 ± 2 to ~6 ± 2 wt% wt%. A change in stress state occurred within the first day of incubation; where after, with further exposure time the stress state converted back to values similar to that of the assprayed condition.

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Microstructural characterisation and stress determination in as-plasma sprayed and incubated bioconductive hydroxyapatite coatings

Cited by 24 publications

References 41 publications

Bioactivity of cement type bone substitutes

Bioactivity of cement type bone substitutes

Osseoconductive and Corrosion-Inhibiting Plasma-Sprayed Calcium Phosphate Coatings for Metallic Medical Implants

In-vitro Investigation of Air Plasma-Sprayed Hydroxyapatite Coatings by Diffraction Techniques

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