Papers by Keyword: Self-Sealing

Abstract: By using a 1D column geometrical model this paper carried out research on the effects of CO2 penetration on the caprock properties. The result show that due to CO2 ingression the formation water environment changed greatly. The pH reduced to 3.8 from initial 7.48 and then buffered to 5.6; The supercritical CO2 reached to 0.006 m in the caprock, but aqueous CO2 reached to 1.1 m. The self-sealing efficiency worked after about 25 years, and the relevant minerals were calcite, quartz, kaolinite and calcite. The research will provide some technical reference for site selection of CO2 geological storage projects and CO2 leakage assessment.

Abstract: By designing different formulations of composites and adopting optimized technology including extrusion and molding, the different composites with various content microcapsules were prepared. The results of the tensile tests show that with the increasing content of self-healing microcapsules in the glass fiber reinforced nylon composites, the mechanical properties of the composites will change, i.e. tensile strength, elastic modulus will decrease. But there is little effect on the mechanical properties of the composite gears if the content of self-healing microcapsules is less than 3.5%, and the technology of self-healing microcapsules used in the polymer composite gear is feasible.

Abstract: In order to study the effect of RE on anti-corrosion mechanism, high Mg content Zn-Al-Mg and Zn-Al-Mg-RE (where RE is Rare Earth) alloy coatings were produced on low carbon steel substrates by using cored wires and arc spraying. The electrochemical impedance spectroscopy (EIS) was used to determine the anti-corrosion mechanism of the two coatings in 5% NaCl solution. The composition and structure of corrosion products on the coatings surface have been investigated after corrosion tests by X-ray diffractometer (XRD). The results show that, Zn-Al-Mg-RE coating has superior corrosion resistance compared to Zn-Al-Mg coating due to the formation of more compact and uniform corrosion products. The self-sealing effect of the Zn-Al-Mg-RE coatings, especially for longer immersion times is extremely good. The role of the RE elements appears to be associated with the self-sealing process and the refinement of the coating microstructure.

Abstract: Cored wires and arc spraying technique were used to produce Zn-Al-Mg-RE alloy coatings on low carbon steel substrates. The effect of RE (where RE is Rare Earth) on the microstructure and electrochemical corrosion behavior of coatings was investigated comparing with Zn-Al-Mg coatings. With addition of RE, the Zn-Al-Mg-RE coating has denser microstructure and fewer porosity. But RE has no discernible effect on the adhesion strength between coating and substrate. The Zn-Al-Mg-RE coating has superior corrosion resistance compared to Zn-Al-Mg coating due to the formation of more compact and uniform corrosion products. The role of the RE elements appears to be associated with the self-sealing process and the refinement of the coating microstructure.

Abstract: By designing the different formulations of the composites and adopting optimized technology including extrusion and molding, the effects of the Micro-capsules on the properties of nylon composites are analyzed by the impact property test. The mechanical impact property of the glass fiber reinforced nylon composites is influenced little if the content of the self-healing microcapsules added is less than 3.5%, and the technology of self-healing microcapsules used in the polymer composite gear is feasible.

Abstract: Cored wires and arc spraying were used to produce high Mg content Zn-Al-Mg alloy coatings on low carbon steel substrates. And the corrosion mechanism of the Zn-Al-Mg coatings was investigated comparing with Zn-Al alloy coatings by X-ray diffractometer (XRD) and Electrochemical impedance spectroscopy (EIS). The results show that, The Zn-Al-Mg coatings show higher electrochemical corrosion resistance in salt solution than Zn-Al coatings. With addition of Mg, the corrosion products can block off the pores in the Zn-Al-Mg coating, which is so-called self sealing, and thus prevent attack on the underlying steel substrate.

Abstract: Cored wires and high velocity arc spraying (HVAS) technologies have been applied to produce Zn-Al-Mg-RE coating on A3 steels. The durability of coating in terms of corrosion resistance is the focus of this paper. The detailed degradation mechanism has been investigated using electrochemical-monitoring techniques supported by precise pre-test and post-test microscopical examination using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Zn-Al-Mg-RE coating shows a typical aspect of layered heterogeneous structure, the existing of ZnAl2O4 and MgAl2O4 implies the good anti-corrosion feature. The polarization curves showed that Zn-Al-Mg-RE coating exhibits passive behavior at 0.5h and 16h immersion, but at 600h, it begins to dissolute. In contrast, the anti-corrosion performance isn’t cut down. The corrosion potential moves to the noble direction step by step, along with the current density drops gradually. After corrosion, it has been observed that the coating surface is jointed by flaky lamellar products and dense without obvious defects and pores. It is postulated that with the addition of RE, the porosity of the coating is reduced, meanwhile, the stability of the products layer can reinforce the self-sealing effect of the coating distinctively.