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 (L_C1, L_C2, and L_C3) 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 (R_p = 65.85 kΩ/cm²; I_corr = 0.63 µA/cm²; E_corr = −167 mV/ECS) compared to as-deposited and uncoated samples.

In this paper, 45S5 Bioglass^® coatings were elaborated by electrophoretic deposition (EPD) on the titanium alloy Ti6Al4V. An adequate grinding protocol was developed to obtain a stable suspension of submicrometric particles in isopropanol. The voltage and the deposition time of EPD were optimized. An optimal voltage of 30 V and two deposition times (30 and 90 s) were chosen to obtain two different coatings with thicknesses of 21 and 85 µm, respectively. The as-deposited coatings were thermally treated following a two-step protocol: one hour at 120 °C followed by one hour at 450 °C. The surface morphology and the chemical analysis of the 45S5 Bioglass^® coatings were assessed, before and after heat treatment, by scanning electron microscopy associated to X-ray microanalysis (SEM-EDXS). Their structural analysis was performed by X-ray diffraction (XRD). A scratch test study was developed for mechanical properties analysis. The obtained results revealed that the obtained coatings were homogeneous, weakly crystallized with an important compactness. An increase in the critical load L_C associated with the cohesive limit of the film (from Lc = 3.39 N to Lc = 5.18 N) was observed when the coating thickness was decreased from 85 to 21 µm. After the thermal treatment, the chemical composition of the coatings was not altered, and their mechanical properties were improved.

To increase the lifetime of metallic molds and protect their surface from wear, a fluorinated ethylene propylene (FEP) polymer was coated onto a stainless-steel (SS304) substrate, using an air spray process followed by a heat treatment. The microstructural properties of the coating were studied using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) as well as X-ray diffraction. The mechanical properties and adhesion behavior were analyzed via a nanoindentation test and progressive scratching. According to the results, the FEP coating had a smooth and dense microstructure. The mechanical properties of the coatings, i.e., the hardness and Young’s modulus, were 57 ± 2.35 and 1.56 ± 0.07 GPa, respectively. During scratching, successive delamination stages (initiation, expansion, and propagation) were noticed, and the measured critical loads L_C1 (3.36 N), L_C2 (6.2 N), and L_C3 (7.6 N) indicated a high adhesion of the FEP coating to SS304. The detailed wear behavior and related damage mechanisms of the FEP coating were investigated employing a multi-pass scratch test and SEM in various sliding conditions. It was found that the wear volume increased with an increase in applied load and sliding velocity. Moreover, the FEP coating revealed a low friction coefficient (around 0.13) and a low wear coefficient (3.1 × 10⁻⁴ mm³ N m⁻¹). The investigation of the damage mechanisms of the FEP coating showed a viscoelastic plastic deformation related to FEP ductility. Finally, the coating’s resistance to corrosion was examined using electrochemical measurements in a 3.5 wt% NaCl solution. The coating was found to provide satisfactory corrosion protection to the SS304 substrate, as no corrosion was observed after 60 days of immersion.

CrSiN coating was deposited by PVD magnetron sputtering on XC100 steel substrate. Microstructural and morphological properties were studied using SEM/EDS, XRD and AFM. Nanoindentation and scratching experiments were conducted to study the mechanical and adhesion behavior. Multi-pass scratch tests were conducted under different sliding conditions. Results showed that CrSiN coating has a dense and compact nanocomposite microstructure consisting of CrN nanocrystallites and SiN amorphous matrix. The CrSiN thin film exhibit, hardness and Young's modulus of 30.52 ± 1.85 GPa and 338.32 ± 13.5 GPa respectively. The H/E, H³/E² and 1/HE² ratios were also calculated (H/E ≈ 0.09, H³/E² ≈ 0.024 and 1/HE² ≈ 2.86 × 10⁻⁰⁷) and used to predict and assess the elastic/plastic and wear resistance. Critical loads LC1, LC2 and LC3 obtained with scratch test, were respectively 11.5 ± 0.12, 16.6 ± 0.23 and 20 ± 0.35N. Multi-pass scratch were analyzed and the friction coefficient (COF), the damage mechanism and wear volume were determined. The use of an energetic approach allowed to determine of the energetic wear coefficient. CrSiN coating revealed a low friction coefficient (around 0.1) and a low energetic wear coefficient (6.3 × 10⁻⁷ mm³/N.m). In addition, it was found that multi-pass scratch method has the potential to extract relevant information about wear behavior.