Interfacial Characteristics and Determination of Cohesive and Adhesive Strength of Plasma-Coated Hydroxyapatite via Nanoindentation and Microscratch Techniques

Abstract

We investigate the chemical composition and mechanical properties of plasma-deposited hydroxyapatite on grit-blasted Ti-6Al-4V coupons as models of typical prosthetic hip implants. Nanoindentation is used to extract the mechanical properties of the hydroxyapatite (HA) coating and to evaluate the behavior of the material as a function of distance from the interface. A microscratch technique was used to determine parameters of cohesive and adhesive failure of the material that are critical in determining the functionality of these biomedical devices. This delamination method has not been studied in detail before and is usually considered to be unsuitable because of the thickness of the HA and the roughness of the substrate. However, through cross-section analysis of the scratch test, we can determine the point at which the HA delaminates from the substrate. It was concluded that spallation occurs locally, and there is no evidence of gross spallation, indicating that the coating is well adhered to the substrate.

Higher in-flight particle velocities enhance in vitro tribological behavior of plasma sprayed hydroxyapatite coatings

“…On the other hand, some other studies reported much lower E and H values. For instance, McManamon et al [22] found that their plasma sprayed HA coatings possessed a E of 4.1 GPa and a H of 0.29 GPa; low E (6 GPa) and H (1 GPa) were also obtained by Sidane et al [23] for their sol-gel HA coating, although they used the same indentation depth and strain rate as our study. These results suggest that the mechanical properties of HA coatings depend on various factors such as crystallinity, porosity, particle size and processing routes.…”

Calcium orthophosphate deposits: Preparation, properties and biomedical applications

“…28. Furthermore, fatigue [148,774], scratch [744,749,[775][776][777][778][779] and pullout [775] testing, as well as wear resistance [777] are among the most valuable techniques to provide additional information on the mechanical behavior of CaPO 4 deposits. The scratch test is performed with reference to ISO 20502:2005 [780].…”

Clinoenstatite coatings have high bonding strength, bioactive ion release, and osteoimmunomodulatory effects that enhance in vivo osseointegration

“…The primary and most basic property is to achieve high bonding strength in the interface between the coating material and metal substratum. Due to hydroxyapatite's (HA) close similarity with the predominant inorganic component of bone, HA coatings have been widely applied to modify the metal substratum [8,9], resulting in high cytocompatibility and osteogenic effects. Implants modified this way have been shown to integrate better with the host bone tissue, leading to a higher success rate of implantations.…”