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• Hydrothermal treatment was applied to TiN coating for surface oxidation. • Anatase nanoparticle and nanolayer were formed on TiN. • Corrosion resistance of TiN was greatly enhanced even in present of fluoride ions. Titanium nitride (TiN) coating is a promising to be used on metal implant and surface oxidation by hydrothermal treatment has been proved to effectively enhance its osteoconductivity. In this study, the physicochemical properties and corrosion resistance of the TiN coating after hydrothermal treatment in distilled water were investigated. The results showed that, Anatase-type titanium oxide (TiO 2) nanoparticles formed on the TiN surface once the temperature was over 150 °C and that they formed a compact layer when the temperature increased to over 200 °C. The treatment significantly improved the wettability of TiN coating. Although surface hardness of TiN coating decreased slightly after formation of oxide layer, it could still provide enough protection for substrate. Electrochemical experiments showed that corrosion resistance of TiN was greatly improved in present of fluoride ions (F−). Immersion test for 5 weeks showed that numerous corrosion pits appeared on untreated TiN coating, whereas, the TiO 2 layer on treated TiN coating remained intact and provided good protection for the underlying TiN. This work showed that hydrothermal treatment at 200–250 °C could comprehensively improve the properties of TiN coating necessary for biological applications and it also provide a possible solution to improve corrosion resistance of hard TiN coating on metal substrates. [ABSTRACT FROM AUTHOR]

With the environmental pollution caused by solvent-based coatings gets worse and worse, it is urgent to improve the anticorrosion property of waterborne coatings. As we all know, the coating showed better corrosion resistance because of the adding of curing agent. And tetra- n -butyl titanate is a coupling agent with excellent properties. But the waterborne epoxy coatings' feature of hydrolyzing easily limits its development. This study aimed to investigate the protection performance of the epoxy ester coatings with titanium ion curing agent (EC). To obtain excellent water resistant coatings, butyl titanate improved by ethylene glycol and triethanolamine is used as curing agent (ranged from 2 to 8 wt%) for epoxy ester resin. The chemical structures of the prepared coatings were analyzed by Fourier transform infrared spectroscopy (FTIR). And field emission scanning electron microscope (FESEM) was used to observe the coatings' surface morphologies. The corrosion resistance of the coatings was also examined by means of electrochemical impedance spectroscopy (EIS), surface topography and Copper-accelerated acetic acid-salt spray testing (CASS). From the FTIR spectra it was observed that demonstrated peak shift and changed in intensity with the adding of titanium ion curing agent. The corrosion resistance of the epoxy ester coating cured with titanium ion curing agent increased obviously. Its impedance reached 10 8 Ω cm 2 , and it still remained as high as 10 7 Ω cm 2 even after immersion in 3.5 wt% NaCl solution for 40 days. Not only that, but the coating showed better corrosion resistance than other coatings when the curing agent's dosage increased to 5%. In addition, the observation of surface topography and CASS test confirmed with the results obtained from EIS. [ABSTRACT FROM AUTHOR]

Surface oxidation is found to improve the osseointegration of titanium nitride (TiN) coatings on implantable titanium devices; nevertheless, systematic studies on effects of oxidation are still needed. In this study, multi-arc ion plated (MAIP) titanium nitride (TiN) coating was hydrothermally oxidized in pure water and then the structural, corrosion and wear properties of the coating were studied. A dense oxide layer of 20–50 nm in thickness is formed on TiN after hydrothermal oxidation above 200 °C. The layer is composed of flat anatase particles with a length of 50–150 nm and smaller anatase nanocrystallines located on their surface. The passivation behavior of TiN becomes much stronger in simulated saliva after oxidation treatment, showing a wider passivation range, a lower corrosion current and greatly improved impedance. In addition, the open circuit potential (OCP) of oxidized TiN remains much higher than that of untreated after 50 days of immersion. Sliding friction experiments against zirconia (ZrO 2) ceramic balls show that the wear type for the untreated TiN coating involves severe plowing and deformation. In contrast, only slight plowing is found on the surface of TiN covered with a compact anatase layer; the friction coefficient decreases sharply and the wear loss decreases obviously. [Display omitted] 1. Anatase nanolayer forms on TiN coating after hydrothermal oxidation in water. 2. Hydrothermal oxidation improves corrosion resistance of TiN in artificial saliva. 3. Anatase nanolayer contributes to obvious lubrication and wear reduction. [ABSTRACT FROM AUTHOR]

The development of waterborne coating is essentially important for environmental protection, and cross-linking agent is of great significance for ensuring corrosion resistance of the coating. In this work, tetrabutyl titanate was modified by ethylene glycol and tris(2-hydroxyethyl) amine and used for the solidification of waterborne acrylic-epoxy resin. Fourier-transform infrared spectroscopy (FTIR) analysis revealed that the agent reacted with OH groups first to cross-link the resin preliminarily, and then, when the amount of agent was further increased, the amino groups opened epoxide rings resulting in a secondary cross-link. Field emission scanning electron microscope (FESEM) observation and electrochemical impedance spectroscopy (EIS) test found that, when the cross-linking agent was used at 6%, the coating remains intact and kept an impedance of as high as 108Ωcm2 even after being immersed in NaCl solution for 30 days. Copper-accelerated acetic acid-salt spray (CASS) test confirmed that the coating containing 6% cross-linking agent provided the best protection for the carbon steel substrate. [ABSTRACT FROM AUTHOR]

• Stannate bath was used to modify Mg particles in Mg-rich primer on AZ91D magnesium alloy. • A Mg stannate film formed on the surface of Mg particles and could reduce the reaction rate of pure Mg particles. • The stannate treatment made the corrosion products in coating compact and generated a Mg stannate film on AZ91D substrate. • The stannate treatment improves corrosion resistance of the Mg-rich primer on AZ91D alloy greatly. A stannate bath was used to pretreat Mg particles in an Mg-rich primer (MRP) coated on the AZ91D magnesium alloy. The duration of the stannate treatment and its effects on the MRP were investigated. After about 20 min of stannate treatment, a protective film of Mg stannate was formed on the surface of the Mg particles and could decrease the corrosion rate of pure Mg. In the first stage, the Mg stannate film reduced the reaction rate of pure Mg particles, prolonging the lifetime of the MRP. In addition, the stannate treatment caused the formation of compact corrosion products in the MRP, improving the barrier effect of the primer. Finally, a protective film consisting of Mg stannate was formed on the AZ91D substrate. The protective film could reduce the corrosion rate of the AZ91D alloy, improving the protective performance of the MRP. [ABSTRACT FROM AUTHOR]