No abstract

No abstract

No abstract

In this work, 45-120 μm thick, composite Al 2 O 3 /PEEK coatings were fabricated on the Ti-13Nb-13Zr alloy substrate using electrophoretic deposition. The anodic co-deposition of alumina and PEEK particles were investigated and discussed. The asdeposited coatings exhibited the uniform distribution of a nearly amorphous PEEK and crystalline alumina powders on the titanium alloy substrate. The morphology of PEEK in the coatings was changed by heating above the PEEK melting point from granular into dense coating matrix with semi-crystalline structure and spherulitic morphology. Scanning and transmission electron microscopy investigation of the coating microstructure revealed the presence of uniformly distributed Al 2 O 3 nanoparticles and their agglomerates within the PEEK matrix. Micro-scratch tests indicated that the coatings are characterized by excellent adhesion to the underlying substrate. The Al 2 O 3 /PEEK coatings significantly improved the wear resistance and reduced coefficient of friction of the Ti-13Nb-13Zr alloy during dry sliding, also in comparison with a polymer PEEK coated alloy. However, the wear resistance of the Al 2 O 3 /PEEK coated alloy during sliding in Ringer's solution was less than the PEEK coated alloy. The coatings increased the corrosion resistance of the alloy in Ringer's solution. The coatings were also found to be cytocompatible with Among biometallic materials, titanium alloys are increasingly used in medicine as implant material, due to their favorable mechanical properties, low elastic modulus, good electrochemical corrosion resistance and relatively good biocompatibility.1-4 Generally, β and near-β (including Ti-13Nb-13Zr) alloys have about 30% lower Young's modulus than that of two phase α+β alloys. 5 In the case of Ti-13Nb-13Zr alloy the elasticity modulus is reduced by Nb, 6 while Zr is neutral for both the α and β phase. The uses of all titanium alloys in applications exposed to abrasive wear in orthopedic surgery and traumatology, for example, in the head and acetabulum of hip endoprostheses, are limited. This is because of their relatively low hardness, low resistance to abrasive wear, high and unstable coefficient of friction (COF), severe adhesive wear and tendency to seize. 1,[7][8][9][10][11][12] Therefore, in order to improve the bio-tribological performance of titanium alloys, surface treatment is necessary.In recent years, polyetheretherketone (PEEK) coatings have often been applied as solid lubricant films in bio-tribosystems because of their notable wear resistance, corrosion resistance and self-lubricating capacity.13,14 PEEK, with a basic formula of (-C6H4-O-C6H4-O-C6H4-CO-)n, is a polyaromatic, semi-crystalline thermoplastic polymer exhibiting a superior combination of strength, stiffness, toughness and good biocompatibility. 15 Numerous studies have confirmed the successful clinical performance of PEEK for in vivo medical device applications, in orthopedic and spine implants. 13,[15][16][17][18] A number of studies [19][20][21] have also been conducted to d...

No abstract

No abstract

Nanocomposite Si3N4/PEEK 708 coatings were successfully fabricated on the Ti-6Al-4V alloy substrate by electrophoretic deposition (EPD) and post-EPD heat treatment. The addition of chitosan polyelectrolyte into ethanolic-based suspensions enabled the cathodic co-deposition of ceramic and polymeric particles. Zeta potential measurements allowed the elaboration of stable suspensions. The selection of the optimal EPD voltage and time enabled uniform coatings to be obtained. Heating above the PEEK melting point and cooling with a furnace or in water resulted in the formation of dense coatings with semi-crystalline or amorphous polymer structures, respectively. Both coatings with a thickness in the range of 90–105 µm had good adhesion and scratch resistance to the substrates, despite the presence of relatively high degrees of open porosity. The coatings improved the tribological properties of the titanium alloy. However, a strong relationship between the polymeric matrix structure and wear resistance was observed. Semi-crystalline coatings proved to be significantly more wear resistant than amorphous ones.

In this study, molybdenum disulfide nanosheets, bioactive hydroxyapatite particles of two types in various amounts, and PEEK 704 microparticles were electrophoretically co-deposited to fabricate multicomponent coatings on Ti-13Nb-13Zr alloy substrates. A mixture of pure ethanol and cationic chitosan polyelectrolyte was used as a dispersion medium. The kinetics and mechanism of deposition were investigated. The kinetics depended significantly on the suspension’s chemical composition and the voltage used during EPD. Cationic chitosan provided the steric stabilization of the suspension and enabled cathodic co-deposition of all coating components. Green macroscopically homogeneous coatings were subsequently heat treated. The treatment densified the coatings and caused the formation of a stable semi-crystalline PEEK matrix consisting of spherulites. The MoS2 nanosheet packages, separate HA particles and their agglomerates were embedded in the coating matrix. After heat treatment, both types of coatings, differing in HA type, were characterized by excellent adhesion to the substrate and moderate scratch resistance. During surface topography investigation, it was found that coatings containing smaller HA nanoparticles had a slightly lower surface roughness. The coatings raised the corrosion resistance of the titanium alloy substrate in Ringer’s solution. The possibility of the electrophoretic co-deposition of various ceramic and PEEK particles to develop multicomponent coatings, as well as their contribution to enhancing titanium alloy surface properties, represents an important input in further developing superior bioactive titanium implants.