Biocompatibility,corrosion resistance and antibacterial activity of TiO2/CuO coating on titanium

In this work, TiO₂/CuO coating was prepared on titanium (Ti) by combination of magnetron sputtering and annealing treatment. The microstructure, biocompatibility, corrosion resistance and antibacterial property of TiO₂/CuO coating were investigated in comparison with pure Ti and TiO₂ coating. The results show that TiO₂/CuO coating is mainly composed of TiO₂ and CuO. In vitro cytocompatibility evaluation suggests that no obvious toxicity appears on the TiO₂/CuO coating, and the coating stimulates the osteoblast spreading and proliferation. Compared with Ti and TiO₂ coating, TiO₂/CuO coating exhibits improved corrosion resistance and antibacterial ability against S.aureus. This study is the first attempt to apply the combination of magnetron sputtering and annealing treatment to introduce the Cu into TiO₂ coating for surface modification of Ti-based implant materials, which may provide a research foundation for further development of bioactive multifunctional coatings to meet the better clinical demand.     

Multifunctional ZnO/TiO2 nanoarray composite coating with antibacterial activity,cytocompatibility and piezoelectricity

Metal oxides with nanostructures such as zinc oxide (ZnO), titanium dioxide (TiO₂) have been used in biomedical fields for their multifunctional properties. In this study, ZnO/TiO₂ nanoarray (nZnO/TiO₂) coatings were prepared via hydrothermal synthesis followed by low temperature liquid phase method. The particle size of the composites were no more than 100 nm in diameter, assembled into nanoarray on the Ti substrate. In vitro antibacterial experiments showed that the maximum bacteriostatic rate could reach 99% against Staphylococcus aureus and 90% against Escherichia coli, respectively. Moreover, the nZnO/TiO₂ coatings were of cytocompatibility and biocompatibility, promoting the proliferation of MC3T3-E1 and the expression of alkaline phosphatase (ALP). The piezoelectric properties of nZnO/TiO₂ coatings were preliminarily investigated. The smaller the size of the composite particle was, the better the antibacterial property, biocompatibility and piezoelectric properties were. Under the stimulation of the periodic loading, the growth of MC3T3-E1 was promoted, so the secretion of ALP was. The nZnO/TiO₂ composite coating with antibacterial activity, osteogenesis and intellectual stimulation would be a promising smart coating for orthopedic implants.     

A novel non-skid composite coating with higher corrosion resistance

In this work, low-pressure cold-sprayed Ni-Zn-Al₂O₃ intermediate layers were deposited between supersonic–plasma-sprayed NiCr-Cr₃C₂ surface layers and underlying low-carbon steel layers to form a sandwich structure that enhances the corrosion resistance of non-skid NiCr-Cr₃C₂ coatings. The corrosion performance of these bi-layer non-skid coatings and that of a single-layer coating were investigated through electrochemical measurements and observations of their corrosion morphologies. The novel non-skid coating with a top layer possessing a fine powder grain size exhibited the best corrosion resistance because of the pseudopassivation of the interlayer and physical barriers created by the corrosion process. The intermediate layer substantially improved the corrosion resistance of the non-skid coatings.     

Oxidation behaviour and microstructure of a dense MoSi2 ceramic coating on Ta substrate prepared using a novel two-step process

Tantalum (Ta) alloys are important ultra-high-temperature structural materials owing to their excellent high-temperature mechanical properties and processability. However, they exhibit poor high-temperature oxidation resistance. In this study, a dense MoSi₂ ceramic coating was prepared on a Ta substrate using an innovative multi-arc ion plating process and halide activated pack cementation in order to improve its ultra-high-temperature oxidation resistance. This ceramic coating exhibited a low roughness space arithmetic (287.1 ± 26.3 nm) and a dense structure. The relationship between the thickness of the coating and the duration of pack-cementation at 1250 ℃ was parabolic. The coating had a service life of more than 12 h at 1750 ℃, and showed excellent high-temperature oxidation resistance because of the uniform and dense structure of the coating and the rapid formation of a dense SiO₂ layer with low O₂ permeability during high-temperature oxidation.     

镍/纳米二氧化硅纳米复合镀层耐腐蚀性能的研究

制备了纳米氧化硅镍复合镀层材料,并利用静态浸泡法对纯镍镀层和由镀液中不同微粒含量制备的复合镀层样品的耐蚀性能进行了研究,讨论镀液中纳米微粒含量对镀层抗蚀性能的影响。并用扫描电镜观察镀层的表面形貌。     

Construction of g-C3N4/TiO2/Ag composites with enhanced visible-light photocatalytic activity and antibacterial properties

In this study, the multifunctional carbon nitride based composite graphitic-C₃N₄ (g-C₃N₄)/TiO₂/Ag was prepared through a simple and efficient vacuum freeze-drying route. TiO₂ and Ag nanoparticles were demonstrated to decorate onto the surface of g-C₃N₄ sheet. In the ultraviolet–visible absorption test, a narrower band gap and red-shift of light absorption edge were observed for g-C₃N₄/TiO₂/Ag compared to pristine g-C₃N₄ and single-component modified g-C₃N₄/TiO₂. The photodegradation property of g-C₃N₄/TiO₂/Ag was investigated toward the degradation of methylene blue (abbreviated as MB) under the irradiation of visible light. These results indicated that the degradation performance of organic dyes for g-C₃N₄/TiO₂/Ag was obviously improved compared with g-C₃N₄/TiO₂ and g-C₃N₄. The reaction rate constant of MB degradation for g-C₃N₄/TiO₂/Ag was 4.24 times higher than that of pristine g-C₃N₄. In addition, such rationally constructed nanocomposite presented evidently enhanced antibacterial performance against the Gram-negative Escherichia coli. Concentration dependent antibacterial performance was systematically investigated. And 84% bacterial cell viability loss had been observed at 500 μg/mL g-C₃N₄/TiO₂/Ag within 2 h visible light irradiation.     

Synthesis and characterization of Ni-W/TiN nanocomposite coating with enhanced wear and corrosion resistance deposited by pulse electrodeposition

To enhance mechanical properties and anti-corrosion capability of Ni-W alloy further, Ni-W/TiN nanocomposite coating has been co-deposited via pulse current co-deposition in this work. The effects of TiN nanoparticles and operating parameters on the structure and properties of the deposited coating were examined. It illustrated that the nanocomposite coatings are uniform, dense and crack-free, exhibiting dome-like or hill-valley like structure. The particles were homogeneously incorporated in the metallic matrix. RTC analysis indicated that the preferred orientation of Ni-W/TiN was (111) texture. The crystallite size was of 10–16 nm, indicating the formation of nanocrystalline structure. TiN concentration, duty cycle and frequency could influence the amount of TiN particle and W element in the coating, then regulating hardness and anti-wear behaviors. The low duty cycle and long deposition time could diminish the roughness of the coating. The inclusion of TiN nanoparticles in the nickel matrix could promote the nucleation of fresh nickel crystals and restrict the growth of already formed nickel grains, favoring the homogeneous growth and grain refinement of Ni-W crystals. The doped TiN particles would favor the preferred orientation (111) plane, enhanced the hardness, wear and corrosion resistance of Ni-W alloy. Electrochemical results illustrated that the best corrosion-resistant properties of the nanocrystalline coating could be obtained at TiN 30 g L⁻¹, duty cycle of 20% and frequency of 60–200 Hz. The enhanced mechanical properties and corrosion resistance of Ni–W/TiN coating benefits its application in harsh corrosive environment.     

Mechanical,biocorrosion, and antibacterial properties of nanocrystalline TiN coating for orthopedic applications

The current study analyzes the surface, mechanical, biocorrosion, and antibacterial performances of a nanocrystalline TiN ceramic coating synthesized using cathodic arc-physical vapor deposition (PVD) on biomedical Ti6Al4V substrates. The surface hardness and modulus of elasticity were assessed using the microindentation method. The adhesion, friction coefficient, and antibacterial properties of the coating were evaluated. The in vitro corrosion of the prepared coated Ti alloy substrate was analyzed in simulated body fluid (SBF) via cyclic potentiodynamic polarization (CPP), dynamic electrochemical impedance spectroscopy (DEIS), and scanning vibrating electrochemical technique (SVET). The results demonstrated that a nanocrystalline TiN coating with a crystallite size of 10.33 nm and a thickness of 5 μm was formed with good adhesion on the alloy surface. The coating had an enhanced surface hardness of 38.63 GPa and a modulus elasticity of 358 GPa, and exhibited enhanced resistance to plastic deformation compared with the substrate – features that can enhance the service life of an implant. The antibacterial experiments indicated an upgraded antibacterial performance of the TiN coating compared to the bare alloy. The in vitro corrosion-resistance analyses confirmed the enhanced surface protective performance of TiN ceramic coatings against biocorrosion in SBF. The results showed higher impedance values in DEIS, a higher passive region in the CPP analysis, and a lower anodic current density in the SVET analysis compared with the bare substrate.     

Fabrication of Ni-W-B4C composite coatings and evaluation of its micro-hardness and corrosion resistance properties

Boron carbide (B₄C) particles were embedded in nickel-tungsten (Ni-W) coatings by pulse current electrodeposition technique. Physical properties of the composite coatings were studied by XRD, SEM, EDS and Vickers micro-hardness instrument. Corrosion protection of the deposited films was investigated utilizing potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS). Results exhibited that the addition of B₄C nanoparticles into the Ni-W alloy can significantly improve the surface morphology and the micro-hardness of the composite coatings. The corrosion resistance of Ni-W-B₄C nanocomposite is much better than Ni-W alloy deposit, especially when the concentration of B₄C nanoparticles is 2?g/L in plating bath, the obtained Ni-W-B₄C composite coating has the best surface morphology, the highest micro-hardness and the excellent corrosion resistance.     

Polyetheretherketone/Nano-Ag-TiO2 composite with mechanical properties and antibacterial activity

Polyetheretherketone (PEEK) is of interest because of its excellent biocompatibility. However, the lack of antimicrobial activity of PEEK limits its use in clinical applications. Silver-loaded nano titanium dioxide (Nano-Ag-TiO₂)/PEEK composites with different mass fractions (1, 2, 3, and 4 wt%) were prepared by hot compression molding to achieve better mechanical and antimicrobial properties. The results of scanning electron microscopy (SEM) and energy dispersive spectrum (EDS) showed that Nano-Ag-TiO₂ successfully modified PEEK. The contact angle of Nano-Ag-TiO₂/PEEK increased compared to PEEK (p < 0.01). The flexural strength, compressive strength, and Vickers hardness of Nano-Ag-TiO₂/PEEK composites first increased and then decreased. When the Nano-Ag-TiO₂ content is 3 wt%, the flexural strength of Nano-Ag-TiO₂/PEEK composite reaches its maximum, which is 171.19 MPa; the compressive strength reaches the maximum, which is 24.7% higher than that of pure PEEK specimens; the Vickers hardness of Nano-Ag-TiO₂/PEEK composite reaches its maximum, which is 19.84% higher than that of pure PEEK specimens. The in vitro antibacterial evaluation reveals that all Nano-Ag-TiO₂/PEEK samples exhibited good resistance and anti-adhesive properties against Staphylococcus aureus (S. aureus). This finding suggests that the 3 wt% Nano-Ag-TiO₂/PEEK composite has better mechanical properties and antimicrobial ability, which is promising for dental applications.     

A study of the corrosion resistance of a waterborne acrylic coating modified with nano-sized titanium dioxide

The incorporation of nano-sized inorganic pigment particles into organic coatings may offer the potential for improving many of their properties, including corrosion resistance, at relatively low loadings. In the present research, titanium dioxide with a crystallite size of 5-10 nm was added to a waterborne organic primer formulation at loadings from 0.1 to 5% (w/w) and applied to hot-dip galvanized steel (HDG) panels. The corrosion resistance of the modified coatings was measured by neutral salt spray corrosion testing and electrochemical impedance spectroscopy (EIS), with an unpigmented film tested for comparison. 3% (w/w) TiO₂ appeared to produce an optimum improvement in the corrosion resistance.     

Synthesis of a novel nanostructured zinc oxide/baghdadite coating on Mg alloy for biomedical application: In-vitro degradation behavior and antibacterial activities

In this research, zinc oxide (ZnO) and zinc oxide/baghdadite (ZnO/Ca₃ZrSi₂O₉) were prepared on the surface of Mg alloy using physical vapor deposition (PVD) coupled with electrophoretic deposition (EPD). For this purpose, the nanostructured ZnO was prepared with a thickness of 900 nm and crystallite sizes of 64 nm as under layer while nanostructured baghdadite with a thickness of 10 µm was deposited on the Mg alloy substrate as an over-layer. Electrochemical measurement exhibited that the ZnO/Ca₃ZrSi₂O₉-coated specimen has a higher corrosion resistance and superior stability in simulated body fluid (SBF) solution in comparison with the ZnO-coated and bare Mg alloy samples. Antibacterial activities of the uncoated and coated specimens were evaluated against various pathogenic species (Escherichia coli, Klebsiella pneumoniae, and Shigella dysenteriae) via disc diffusion method. The obtained results showed that ZnO and ZnO/Ca₃ZrSi₂O₉ coatings have great zones of inhibition (ZOI) against E. coli, Klebsiella, and Shigella. However, less ZOI was found around the bare Mg alloy. Therefore, ZnO/Ca₃ZrSi₂O₉ is a promising coating for orthopedic applications of biodegradable Mg alloys considering its excellent antibacterial activities and high corrosion resistance.     

The mechanical and thermal properties,CMAS corrosion resistance,and the wettability of novel thermal barrier material GdTaO4

Because the CMAS corrosion and phase transformation at elevated temperatures above 1250 °C have limited the applications of traditional YSZ, the design of novel thermal barrier materials is a hotspot. GdTaO₄ is considered as a type of potential novel thermal barrier material owing to its low thermal conductivity. In this study, the mechanical and thermal properties, CMAS corrosion resistance, and the wettability of the GdTaO₄ were studied and compared with that of YSZ. The results show that the coefficient of thermal expansion and hardness of GdTaO₄ are 14.1 × 10⁻⁶ K⁻¹ (1350 °C) and 534.2 Hv_0.3 respectively. The thickness of CMAS reaction layer of GdTaO₄ is ~30.8 μm after 24 h reaction at 1350 °C, which is thinner than that of YSZ. After corrosion reaction, the CMAS glass aggregated instead of completely disappearing or continuously extending over the surface of GdTaO₄. The main reaction product is Ca₂Ta₂O₇, and the anorthite phase may not be detected, which is similar to YTaO₄. By comparison, the dense substrate of YSZ became porous and CMAS glass has disappeared after 10 h. CMAS corrosion at 1350 °C. The on-line contact angle results show that the wettability of CMAS on GdTaO₄ is worse than that on YSZ at 1350 °C, while the opposite of the work of adhesion, which indicates that GdTaO₄ can remove liquid CMAS more easily than YSZ TBCs during the service. Furthermore, the corrosion depth and areas of GdTaO₄ are smaller than those of YSZ in the same situation. These findings suggest that GdTaO₄ possesses better high-temperature properties and CMAS corrosion resistance than YSZ as a kind of potential of thermal barrier material.     

化学镀制备高耐蚀耐磨Ni-P-SiC复合镀层

研究了Ni-P-SiC复合镀层的制备工艺和性能以及SiC含量对镀层性能的影响。采用Taber试验机对Ni-P-SiC复合镀层的磨损性能进行了测试,并用VHX-100型三维视频显微镜对磨损形貌进行了观察,分析了复合镀层的磨损机理。结果表明:SiC颗粒的加入能有效地降低摩擦副之间的犁沟效应及摩擦表面发生粘着的面积,从而减少镀层的磨损。采用电化学实验等手段研究了Ni-P-SiC复合镀层的耐蚀性能。当复合镀层均匀一致,能起到一个良好的屏蔽作用时,耐蚀性十分优异;而镀层缺陷的存在将导致耐蚀性能降低。     

Efficient one-step fabrication of superhydrophobic nano-TiO2/TMPSi ceramic composite coating with enhanced corrosion resistance on 316L

TiO₂ Nanoparticle/Trimethoxy(propyl)silane (TMPSi) ceramic composite coating was deposited on 316L steel using a one-step electrophoretic deposition (EPD) method. Silane coupling agent (TMPSi) was added to the EPD bath in different concentrations (from 0.5 to 15 vol %) to decrease the surface energy of the deposited coating. TiO₂ coating is hydrophilic whereas by adding varying concentrations of TMPSi, the obtained nanocomposite coating showed much better hydrophobicity. Surface wettability was measured by water contact angle (WCA) and sliding angle (SA) tests. Moreover, the effect of TMPSi concentration was determined by comparing the WCA and SA values. Surface morphology was studied through Field Emission Scanning Electron Microscopy (FESEM), and the presence of micro/nano meter roughness on the surface was confirmed. The distribution of elements were investigated by EDS analysis in which their uniform dispersion was observed. Corrosion behavior of 316L samples before and after the coating process was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in 3.5 wt % NaCl solution. The polarization curve proved that the superhydrophobic ceramic nanocomposite coatings (WCA = 168° and SA = 3.1°) were able to decrease the corrosion rate of bare 316L (from 12.180 to 5.621 (μm per year)).     

Electrodeposited Ni-B alloy coatings: Structure, corrosion resistance and mechanical properties

Ni-B alloy coatings with different boron content ranging from 4 to approximately 28 at.% were prepared by electrodeposition in a nickel-plating bath containing sodium decahydroclovodecaborate as a boron source. The influence of the boron concentration in the coatings on their structure, morphology, electrochemical and corrosion behavior, physico-mechanical and electrical properties was investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and other methods. It was found that the electrodeposited Ni-B coatings with relatively low boron content (≤8 at.%) are nanocrystalline and comprise a solid solution of boron in f.c.c. Ni lattice having a mixed substituted-interstitial type. Further increase in the boron content (up to 10-15 at.%) leads to the appearance of heterogeneous amorphous-nanocrystalline structure, and the coatings with a high boron content (20 at.% and above) are X-ray amorphous. Polarization measurements in neutral NaCl solutions showed that the Ni-B coatings with relatively low boron content demonstrate a potential region of low anodic currents associated with the passive film formation at the alloy surface. The anodic current in this potential region increases significantly with increasing the boron content above 10 at.%, suggesting the non-protective nature of the anodic film formed on the amorphous Ni-B alloys. Immersion tests monitored by EIS measurements revealed a significantly better corrosion performance of the Ni-B coatings with low boron content (4 at.%) in comparison with that of the amorphous coatings. The microhardness and wear resistance of the Ni-B coatings essentially increases with increasing the boron content. Maximum microhardness and wear resistance were found for the coatings containing 8 at.% B.     

In-situ grown Ag on magnetic halloysite nanotubes in scaffolds: Antibacterial,biocompatibility and mechanical properties

A novel design of antibacterial and magnetic halloysite nanotubes loaded with Ag and Fe₃O₄ was reported. In detail, magnetic nanoparticles (Fe₃O₄) were immobilized on the surface of halloysite nanotubes (HNTs) via electrostatic adsorption (termed as HNTs/Fe₃O₄). The magnetic HNTs/Fe₃O₄ was then modified by polydopamine to in-situ grow Ag nanoparticles by a redox reaction, forming a composite nanostructure of HNTs/Fe₃O₄@Ag. The HNTs/Fe₃O₄@Ag was incorporated into poly-l-lactic acid (PLLA) scaffold fabricated via selective laser sintering, with the intent to endow the scaffold with robust antibacterial function and favorable cell activity. The results showed that the released Ag⁺ from the scaffold significantly against E. coli activity, with bacterial inhibition rate above 99%. Moreover, ion release behavior showed a scaffold enable to sustain release Ag⁺ over 28 days. Furthermore, Fe₃O₄ nanoparticles constructed magnetic microenvironment greatly enhanced cell activity and promoted cell proliferation. In addition, tensile strength of the scaffold increased by 52.9% compared with PLLA scaffold. These positive results suggested that the HNTs/Fe₃O₄@Ag nanostructure possessed potential in facilitating bone repair.     

喷涂功率对YSZ涂层的力学性能和抗铝硅熔体腐蚀性能的影响

热浸镀Al–Si合金涂层是一种有效的现代钢铁防腐涂层,但熔融Al–Si合金腐蚀已成为热浸镀Al–Si合金生产线沉没辊及其备件亟待解决的关键问题之一。本工作采用大气等离子喷涂技术制备Y2O3部分稳定ZrO2(YSZ)/NiCrAlY防护涂层,研究了喷涂功率对YSZ涂层组织和力学性能的影响和涂层在700℃下Al–Si熔体中的腐蚀行为。结果表明,YSZ涂层是由板条和层间柱状晶粒组成的典型层状结构,随着喷涂功率从37 kW增至46 kW,层间柱状结晶呈长大趋势;YSZ涂层主要由t-ZrO2相和少量m-ZrO2相组成,喷涂功率对涂层相组成无明显影响;喷涂功率为40 kW的YSZ涂层具有较高的显微硬度642.4 HV0.3和结合强度62 MPa。此外,当带有涂层的样品在700℃的Al–Si熔液中腐蚀240 h后,YSZ涂层与高温Al–Si熔液之间的界面没有反应层生成,同时Al–Si合金熔液中的Al和Si元素也未渗透进YSZ涂层内部,表明YSZ/NiCrAlY防护涂层有效地将Al–Si合金熔体阻挡在涂层表面。     

A new corrosion protection coating with polyaniline-TiO2 composite for steel

Organic coating strategies for corrosion protection with inherently conducting polymers have become important because of restriction on the use of heavy metals and chromates in coatings due to their environmental problems. This work presents the synthesis of polyaniline-TiO₂ composites (PTC) and the corrosion protection behaviour of PTC containing coating on steel. PTC was prepared by chemical oxidation of aniline and TiO₂ by ammonium persulfate in phosphoric acid medium. The PTC was characterized by FTIR, XRD and SEM techniques. Suitable coating with PTC was formed on steel using acrylic resin. Using electrochemical impedance spectroscopy, the PTC containing coating's behaviour in 3% NaCl immersion test and salt spray test has been found out. Results indicate that the coating containing PTC is able to maintain the potential of steel in passive region due to its redox property. The resistance of the coating containing PTC was more than 10⁷ Ω cm² in 3% NaCl solution after 60 days and 10⁹ Ω cm² in the salt spray test of 35 days. But the resistance of the TiO₂ containing coating was found to be less than 10⁴ Ω cm² in both the cases. The high performance of PTC containing coating is attributed to the passivation of steel by polyaniline.     

A novel composite protective coating with UV and corrosion resistance: Load floating and self-cleaning performance

The research in functional materials has been the focus in studying industrial applications, particularly in the field of superhydrophobic functional bionic material. Although many studies of superhydrophobic surfaces have been published at this stage, the performance remain unsatisfactory, especially in a variety of harsh environments in practical applications, such as extremely cold weather, acidic or alkaline environment, prolonged exposure to light, high temperature, or oily wastewater, etc. The mechanical strength and corrosion resistance of coatings in such environments are all mighty challenges. In this study, we propose a fluoro silane-modified zinc oxide (FAS-ZnO) as a nano-filler. A superhydrophobic and oleophobic composite coating was successfully prepared through a single step by spraying suspensions containing attapulgite (ATP), FAS-ZnO, and carboxylated polyphenylene sulfide (PPS–COOH) onto desired substrates. In addition, stearic acid was added as a binder and used to enhance the bonding strength between the filler and the substrate. The composite coatings were characterized by FE-SEM, XRD and FT-IR on substrates, and the corrosion resistance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) and salt spray chamber experiments. The composite coatings showed excellent corrosion resistance due to the synergistic effect of FAS-ZnO and ATP. It was found that the composite coating had good hydrophobic and oleophobic contact angles of 161 ± 1.5° and 159 ± 1°, respectively, which were mainly attributed to the construction of nano-scale structures. It is worth noting that the composite coating performed excellently in chemical stability, self-cleaning performance, UV resistance, anti-fouling function, mechanical strength, and load-bearing floating ability. The coating maintained its highly hydrophobic surface after being stretched through a universal testing machine. Based on the multiple key properties in the composite coating, it can be expected to be applied to large equipment and instrument surfaces in extreme outdoor environments.