Additive manufacturing has revolutionized implantology by enabling the fabrication of customized, highly porous implants. Surface modifications using electrochemical methods can significantly enhance the bioactivity and biocompatibility of biomaterials, including 3D-printed implants. This study investigates novel coatings on 3D titanium (Ti) samples. Mesh Ti samples were designed and subjected to plasma electrolytic oxidation (PEO) to form a calcium phosphate coating. Subsequently, a layer of polydopamine (PDA) was applied. The electrochemical properties and morphology of the coatings were analyzed. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) revealed well-developed coatings containing calcium phosphates (including hydroxyapatite), titanium dioxide, and polymerized dopamine, suggesting promising bioactive potential. Composite layers incorporating PDA exhibited superior protective properties compared to base PEO coatings.

In this study, a calcium-phosphate coating was formed on a Mg–Mn–Ce alloy by the plasma electrolytic oxidation (PEO). The antibiotic vancomycin, widely used in the treatment of infections caused by Staphylococcus aureus (S. aureus), was impregnated into the coating. Samples with vancomycin showed high bactericidal activity against S. aureus. The mechanical and electrochemical properties of the formed coatings were studied, as well as in vitro cytotoxicity tests and in vivo tests on mature male rats were performed. According to SEM, EDS, XRD and XPS data, coatings had a developed morphology and contained hydroxyapatite, which indicates high biocompatibility. The analysis of roughness of coatings without and with vancomycin did not reveal any differences, confirming the high roughness of the samples. During electrochemical tests, an increase in corrosion resistance by more than two times after the application of PEO coatings was revealed. According to the results of an in vivo study, after 28 days of the implantation of samples with calcium phosphate PEO coating and vancomycin, no signs of inflammation were observed, while an inflammatory reaction developed in the area of implantation of bare alloy, followed by encapsulation. Antibiotic release tests from the coatings show a sharp decrease in the concentration of the released antibiotic on day 7 and then a gradual decrease until day 28. Throughout the experiment, no significant deviations in the condition and behavior of the animals were observed; clinical tests did not reveal a systemic toxic reaction.

A novel combined method for the formation of composite coatings on the Mg-Mn-Ce alloy is developed. Ceramic like matrix was formed on the Mg alloy surface by the plasma electrolytic oxidation. Then the samples were subsequently processed by dip-coating in an alcohol suspension of superdispersed polytetrafluoroethylene and spraying with the tetrafluoroethylene telomers solution. SEM, OSP, and SPM was used to study structure of formed surfaces. It was established by measurements of CA and CAH, as well as surface free energy calculations that formed coatings demonstrate superhydrophobic properties due to the presence of an irregular hierarchical surface structure and low surface free energy of fluoropolymers. The coating preserves its hydrophobic properties after exposure to high and low temperatures, for a long time as well as being in corrosive environments. EDS and XRD data analysis confirmed the presence of organofluorine compounds in the composite layers, including in the form of crystalline polytetrafluoroethylene. Using potentiodynamic polarization test and EIS, it was found that the resulting coatings significantly increase the corrosion resistance of Mg material. These data are also confirmed by salt spray tests for 40 days. Incorporation of fluoropolymers additionally decrease coatings coefficient of friction.

Developing anti-icing coatings is an important topic for many scientists. In this work, we describe composite coatings prepared by a combination of plasma electrolytic oxidation and deposition of polytetrafluoroethylene from suspension. The composite layers obtained had high strength and adhesion to metal, which made it possible to use them in extreme environmental conditions. The change in the adhesion strength of ice to the coating surface was considered with various methods for forming composite layers on the surface of the metal and compared with the base PEO layer. The wettability of the resulting coatings as well as the relationship between the contact angle and the ice adhesion strength were evaluated.

The creation of substances and compositions capable of changing their properties depending on environmental conditions is an urgent and promising area of research. This work presents a method for obtaining a polymeric system consisting of polyethylene oxide and tetrafluoroethylene telomers, which film is capable of transition from hydrophilic to hydrophobic properties under the heating (from 60 degrees C), as well as returning to its original properties under ambient conditions. The mechanism of transition of substance's properties from hydrophilic to hydrophobic is proposed.(c) 2021 Elsevier B.V. All rights reserved.

В статье представлен анализ изменения в ходе климатических испытаний в камере соляного тумана защитных свойств композиционных покрытий, полученных на магниевом сплаве МА8 методом плазменного электролитического оксидирования с последующей обработкой в водной суспензии ультрадисперсного политетра­фторэтилена. Изучена динамика изменения электрохимических свойств композиционных полимерсодержащих покрытий. Оценено влияние кратности нанесения композиционного слоя на стойкость покрытий к коррозии. Установлено, что полимерсодержащее покрытие, полученное плазменным электролитическим оксидированием и трехкратной обработкой в суспензии ультрадисперсного политетрафторэтилена, обладает наибольшей стойкостью к коррозионному разрушению в связи с высокой однородностью получаемого композиционного слоя. После 40 сут нахождения в агрессивной коррозионной среде значения поляризационного сопротивления и модуля импеданса для данного вида покрытия выше на один порядок в сравнении с базовым ПЭО-покрытием до начала испытаний. The paper presents analysis of changes in the protective properties of composite coatings obtained on the MA8 magnesium alloy by plasma electrolytic oxidation followed by treatment in an aqueous suspension of superdispersed polytetrafluoroethylene, during salt spray test. The dynamics of changes in the electrochemical properties of composite polymer-containing coatings was studied. The effect of the multiplicity of the application of the composite layer on the corrosion resistance of the coatings was estimated. It was established that the polymer-containing coating obtained by the plasma electrolytic oxidation and threefold treatment in the superdispersed polytetrafluoroethylene suspension has the highest resistance to corrosion due to the greater homogeneity of the obtained composite layer. After 40 days of exposure to an aggressive corrosive environment, the values of polarization resistance and impedance modulus for this type of coating are one order of magnitude higher than those for the base PEO-coating before test.

The process of plasma electrolytic oxidation (PEO) and subsequent fluoropolymer treatment of VT1-0 commercially pure titanium with thermal oxide on the surface has been developed to restore the protective coating, integrity of which was destroyed as a result of long-continued operation. The composition and morphology of coatings before and after restoration have been studied by optical microscopy, SEM, optical laser profilomery, XRD, and EDS analyses. The electrochemical behavior of coatings, as well as bare titanium has been investigated using potentiodynamic polarization tests, EIS, and 7-days immersion in 3% NaCl solution. Additionally, microhardness and wear resistance of the samples have been studied. Coatings wettability has been evaluated by sessile drop method. It has been found that composite layers consist of rutile, anatase and PTFE. It has been established that the formation of composite coating on samples with PEO-layers using polytetrafluoroethylene (PTFE) reduces corrosion current threefold in comparison with the coating obtained using the thermal treatment followed by PEO. Moreover, PEO-coating has shown high corrosion resistance during long-term exposure to 3% NaCl solution. Formed composite surface layer has antifriction properties and reduce wear threefold in comparison with the thermal coating. Composite coating are highly hydrophobic: the contact angle attains 152 degrees.