Nanomechanical Behavior, Adhesion and Corrosion Resistance of Hydroxyapatite Coatings for Orthopedic Implant Applications

Abstract

The aim of this work was to investigate the nanomechanical, adhesion and corrosion resistance of hydroxyapatite (HAP) coatings. The electrodeposition process was used to elaborate the HAP coatings on Ti6Al4V alloy. The effect of hydrogen peroxide concentration H2O2 on the electrolyte and the heat treatment was studied. Surface morphology of HAP coatings was assessed, before and after heat treatment, by scanning electron microscopy associated with X-ray microanalysis (SEM-EDXS). Moreover, X-ray diffraction (XRD) was performed to identify the coatings’ phases and composition. Nanoindentation and scratch tests were performed for nanomechanical and adhesion behavior analysis. The corrosion resistance of the uncoated, the as-deposited, and the heat-treated coatings was investigated by electrochemical test. The obtained results revealed that, with 9% of H2O2 and after heat treatment, the HAP film exhibited a compact and homogeneous microstructure. The film also showed a crystal growth: stoichiometric hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP). After heat treatment, the nanomechanical properties (H, E) were increased from 117 ± 7 MPa and 24 ± 1 GPa to 171 ± 10 MPa and 38 ± 1.5 GPa respectively. Critical loads (LC1, LC2, and LC3) were increased from 0.78 ± 0.04, 1.6 ± 0.01, and 4 ± 0.23 N to 1.45 ± 0.08, 2.46 ± 0.14, and 4.35 ± 0.25 N (respectively). Furthermore, the adhesion strength increased from 8 to 13 MPa after heat treatment. The HAP heat-treated samples showed higher corrosion resistance (Rp = 65.85 kΩ/cm2; Icorr = 0.63 µA/cm2; Ecorr = −167 mV/ECS) compared to as-deposited and uncoated samples.

Encouraging tribomechanical and biological responses of hydroxyapatite coatings reinforced by various levels of niobium pentoxide particles

“…An abrupt increase in friction force and/or coating removal in scratch track corresponds to the critical load. 69 As shown, there are two L c values for the studied coatings, indicating the gradual spallation of the coatings rather than sudden delamination. The latter takes place when there is one L c .…”

Nanomechanical behavior, adhesion and wear resistance of tin oxide coatings for biomedical applications

“…It is also clear that the film is uniform, with no cracks or pores, Figure 3. This morphology generally enhances osseointegration [25][26][27].…”

“…The modulus of elasticity (E IT ) was determined from the discharge curve using the following equation [37,25]:…”

“…It represents the elastic deformation at failure. The resistance to plastic deformation was determined based on the H IT 3 /E IT 2 ratio [25,26]. The elastic recovery rate was given by the ratio (R%) calculated by the following equation:…”

Evaluation of the Cathodic Electrodeposition Effectiveness of the Hydroxyapatite Layer Used in Surface Modification of Ti6Al4V-Based Biomaterials

“…The electrochemical technique is attractive due to its simplicity, low cost, uniformity of the produced coatings, and ability to precisely control the properties of the layers produced (chemical composition, thickness, structure) at low temperatures. It is suitable for coating surfaces with complex geometries [ 16 , 17 , 21 , 32 ]. The major limitation of the electrodeposition technique is the poor adhesion of the HA layer to the implant’s surface [ 16 , 21 , 33 ].…”