Fabrication of corrosion inhibiting microcapsules functional coating and their high-efficiency corrosion resistance

Benzotriazole(BTA)was loaded into calcium carbonate microsphere shell by self-assembly method and a new type of high-efficiency corrosion inhibiting microcapsules(CIMs)were fabricated,which were added and dispersed into epoxy resin coating to obtain a new corrosion resistance functional coating.The corrosion inhibition effect of benzotriazole on aluminum alloy matrix was verified by polarization curve test.The effectiveness of the CIMs and their loading capacity on inhibitor were evaluated by scanning electron microscope,laser confocal Raman spectroscopy together with thermogravimetric analysis.

Morphology,structure and corrosion resistance of Mg-Al LDH films fabricated in different Al^(3+)concentration solutions

In situ-grown Mg-Al layered double hydroxide(LDH)films were obtained on an anodized AZ31 substrate,with the immersion of sample in different concentrations of Al^(3+)solution.The structure,composition and morphology of LDH films were investigated by X-ray diffraction(XRD),Fourier transform infrared(FTIR)and scanning electronic microscopy(SEM),and the corrosion behavior of LDH films was further studied by electrochemical impedance spectroscopy(EIS).The influence of Al^(3+)concentration on the growth behavior of LDH was also discussed.The results indicated that the nest-like structure of MgAl-LDH film was composed of interconnected MgAl-LDH nanosheets.Besides,the LDH obtained in0.032 mol·L^(-1)Al^(3+)solution,possessing dense laminated structure,could effectively seal the porous surface of anodic oxide film.EIS results revealed that the samples coated with LDH films showed a higher electrochemical impedance,and thus,the corrosion resistance of samples coated with LDH films was signally improved compared with the anodized alloy.

Preparation of metal organic framework film on surface of aluminum profile and properties of fluorocarbon powder coating

The chemical pretreatment film on the surface of aluminum profile,the type of fluorocarbon powder and the compatibility between them are the common key problems in the industry of using"powder"instead of"paint"to solve the volatile organic compounds(VOCs)and related organic wastewater discharge in the coating process.In this study,a new type of pretreatment film was prepared on the surface of aluminum profile.It was found that the prepared pretreatment film had a three-dimensional framework s tructure,and the organic matter and titanium salt were connected by the introduction of divalent metal ions to form a metal skeleton film.

Nickel-free sealing technology for anodic oxidation film of aluminum alloy at room temperature

Different additives were added into the potassium fluorozirconate solution to prepare different nickelfree sealing reagents,with which the anodic oxidation film of aluminum alloy was sealed at room temperature.The phosphor chromic acid weight loss method was used to evaluate the sealing effects.Using electron scanning microscopy(SEM),the surface and cross-sectional micromorphologies of the anodic oxidation films sealed by different fluorozirconate sealants were observed.The position and state of zirconium element distribution in the film hole were investigated by the further quantitative and distribution analysis of Zr element.This study provides an experimental evidence for the theoretical studies of fluorozirconate-sealed anodic oxidation films.It is shown that the fluorozirconate has good sealing effects and has a wide prospect for sealing the aluminum alloy samples.Its products were highly corrosion resistant,and were filled in the openings of the micropores in the oxide film.

Characteristics of Ce-Mn film on 6061 alloys and its improved performance

HF2- was applied to accelerate the Ce-Mn film formation on 6061A1 alloy in the Ce3+-MnO4-solution.The process of film formation,the composition and structure of the film were analyzed by scanning electron microscopy(SEM) equipped with energy-dispersive spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS)and X-ray diffractometer(XRD).The film formation process includes three stages.At the initial stage,a threedimensional(3D) skeleton was formed quickly,and then the skeleton was fully filled with cerium oxide and manganese oxide,resulting in a dense structure.Subsequently,a new skeleton was formed and also filled.Al,Ce,O and Mn were detected in the film.Ce existed mainly in the form of Ce4+(89%).The film existed in an amorphous form and was composed of ceria(cerium hydroxide),manganese dioxide and aluminum oxide.After electrostatically spraying fluorocarbon powder,the resultant products satisfied the required mechanical performance and exhibited almost non-filament corrosion compared with commercially available chromium-free conversion film.Its corrosion resistant time to acetate spray can reach 2000 h,which is consistent with that of fluorocarbon paint.The results showed that Ce-Mn film can offer an attractive prospect to eliminate volatile organic compounds(VOC) problem arisen by using fluorocarbon paint in the process of industrial production.

Phase composition, morphology and element contents of micro-arc oxidation ceramic coatings on Ti–6Al–4V alloy under different calcination conditions

Compound ceramic coatings with the main crystalline of Al_2TiO_5（in the as-prepared coating without treatment） were prepared in situ on the surface Ti-6Al-4V alloy by means of pulsed bipolar micro-arc oxidation in Na AlO_2 solution. For the purpose of studying the antioxidation properties of the samples, the coated samples treated in argon and the as-coated samples were calcined in air at 1000 °C. And the related characteristics were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and X-ray fluorescence（XRF） spectroscopy, respectively. The results show that, when it was calcined in air for 1 h, Al_2TiO_5in the as-prepared coating decomposed and transformed into α-Al_2O_3 and rutile TiO_2.However, after almost 4 h in argon, Al_2TiO_5in the asprepared coating decomposed and the final coating surface contents are completely α-Al_2O_3, and those of the middle interface are mainly Al_2O_3 and Ti_2O_3. The morphologies of the coatings after calcination in argon and air are different.High-temperature oxidation occurred violently in the alloy substrate without coatings. Furthermore, the weight gain curves of the as-prepared samples and the coated samples treated in argon both show a parabolic shape.

Novel cemented carbide produced with TiN_(0.3) and high-entropy alloys

High-entropy alloys are suitable for use as a binder for cemented carbides duo to outstanding mechanical, oxidation and wear behavior. Therefore, high-entropy alloy was selected to replace Co and Ni metal bond in this study. The results of X-ray diffraction analysis show that CoCrNiCuMn high-entropy alloy is stabilized in the cemented carbide system. Scanning electron microscope（SEM） fractural morphologies of the cemented carbides added with CoCrNiCuMn show that CoCrNiCuMn distributes in grain boundaries, and the grains are bound tightly together. Furthermore, SEM fractural morphologies of the cemented carbides with 5 wt%, 7 wt%, and 10 wt% CoCrNiCuMn show that CoCrNiCuMn slows the growth of grains, which effectively binders the grains, prevents the generation and propagation of cracks, and finally, greatly improves the toughness of the cemented carbides.According to the results observed in the cemented carbides containing different amounts of CoCrNiCuMn, the hardness level gradually increases with the amount of CoCrNiCuMn; however, a reverse trend is seen in the toughness level. The cemented carbide with 10 wt% CoCrNiCuMn shows the highest toughness value of 7.05 MPa·m^1/2.

Morphology,microstructure and tribological properties of anodic films formed on Ti10V2Fe3Al alloy in different electrolytes

This study investigated the morphology, structure and tribological properties of the three samples produced by anodic oxidation of Ti10 V2 Fe3 Al in a sulfuric/phosphoric acid electrolyte(SPA), a near-neutral sodium tartrate electrolyte without nanoparticles(STA) and a nearneutral sodium tartrate electrolyte with polytetrafluoroethylene(PTFE) nanoparticles(CA) in suspension. The STA film had a surface full of bulges and cracks, the SPA film was porous, and the CA film was nanoporous. The SPA film was mainly composed of anatase TiO2, whereas the STA and CA films were mainly amorphous TiO2 with little anatase. The tribological tests indicated that the SPA sample had a lower wear resistance than the titanium alloy substrate, which was attributed to the shedding of abrasive debris, leading to rapid wear. Both STA and CA samples exhibited much lower wear rates than the titanium alloy substrate, and CA sample displayed the lowest wear rate attributed to the formation of a lubricating layer by PTFE nanoparticles. The wear mechanisms are proposed.