Wpływ chropowatości powierzchni podłoża ze stali konstrukcyjnej na właściwości mechaniczne powłoki PEEK osadzonej elektroforetycznie

The mechanical properties, adhesion and roughness of polymer coatings depend on many factors, including the unevenness of the substrate surface. Nevertheless, the influence of the substrate surface roughness is related to the coating type and substrate material and the used deposition method. Therefore, the effect of the surface roughness of a structural steel substrate on the mechanical properties of a PEEK coating is ambiguous. The indentation tests conducted show that, at a specific load of the indenter, the roughness of the steel substrate surface does not significantly affect the Vicker’s hardness of the tested PEEK coatings. The average Vicker’s hardness and elastic modulus are approximately 300 MPa and 5.6 Gpa, respectively, at the lowest of the applied loads, regardless of the surface roughness level of the steel substrate. Nevertheless, the surface roughness of the steel substrate after fine grinding of Ra = 0.21 μm, compared to the polished one with Ra = 0.005 μm, meant that adhesion improved, and the scratch hardness increased by approximately 130 to 370 [MPa] of the PEEK coating.Właściwości mechaniczne, przyczepność oraz chropowatość powłok polimerowych zależą od wielu czynników, a w tym od nierówności powierzchni podłoża. Niemniej jednak wpływ wielkości chropowatości powierzchni podłoża okazuje się być związany z rodzajem materiału powłokowego i podłoża oraz zastosowaną metodą osadzania. Wobec tego oddziaływanie chropowatości powierzchni podłoża ze stali konstrukcyjnej na właściwości mechaniczne powłoki PEEK osadzanej elektroforetycznie nie jest jednoznaczny. Przeprowadzone badania indentacyjne wskazują, że przy określonym obciążeniu wgłębnika chropowatość powierzchni stalowego podłoża nie wpływa znacząco na twardość Vickers’a badanych powłok PEEK. Średnia twardość Vickers’a i modułu sprężystości wynosi odpowiednio ok. 300 MPa i 5.6 GPa przy najmniejszym z zastosowanych obciążeń, niezależnie od mikronierówności powierzchni stalowego podłoża. Nie mniej jednak większa chropowatość powierzchni stalowego podłoża po szlifowaniu dokładnym rzędu Ra = 0.21 μm, względem polerowanego o Ra = 0.005 μm, przełożyła się na polepszanie adhezji i spowodowała wzrost twardości zarysowania powłoki PEEK z ok. 130 do 370 [MPa]

The Influence of Electrophoretic Deposition Parameters and Heat Treatment on the Microstructure and Tribological Properties of Nanocomposite Si3N4/PEEK 708 Coatings on Titanium Alloy

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

Microstructure and Selected Properties of Advanced Biomedical n-HA/ZnS/Sulfonated PEEK Coatings Fabricated on Zirconium Alloy by Duplex Treatment

In this work, sulfonated polyetheretherketone (S-PEEK)-based coatings, nanocrystalline ZnS and hydroxyapatite (n-HA) particles were developed on Zr-2.5Nb zirconium alloy substrates by electrophoretic deposition (EPD) combined with subsequent heat treatment. The properties of suspensions and deposition kinetics were studied. Cationic chitosan polyelectrolyte ensured the stabilization of the suspension and allowed for the co-deposition of all coating components on the cathode. The heating of the coated samples at a temperature of 450 °C and slow cooling resulted in sulfonation of the PEEK and the formation of dense coatings. The coatings were characterized by high roughness, hardness, modulus of elasticity and adhesion strength. The coatings revealed mild hydrophilicity, improved the electrochemical corrosion resistance of the alloy and induced the formation of hydroxyapatite with a cauliflower-like morphology on its surface during the Kokubo test. This work explored the great development potential of advanced sulfonated PEEK-based coatings, incorporating antibacterial and bioactive components by EPD combined with heat treatment to stimulate the surface properties of zirconium alloy for prospective dental and orthopedic applications. The antibacterial and osteoconductive properties of the obtained coatings should be further investigated