The corrosion behavior of water borne epoxy-ester primer coatings (10% - 50% PVCs) was evaluated through electrochemical techniques such as polarization and impedance spectroscopic (EIS) measurements. Studies were car...The corrosion behavior of water borne epoxy-ester primer coatings (10% - 50% PVCs) was evaluated through electrochemical techniques such as polarization and impedance spectroscopic (EIS) measurements. Studies were carried out for a longer duration of exposure extending up to 60 days in aqueous solution of NaCl (5%). Corrosion current (icorr), Corrosion potential (Ecorr), Coating resistance (Rc), Charge transfer resistance (Rct), Coating capacitance (Cc), Double layer capacitance (Cdl), break point frequency (fb), Water uptake (∮), diffusion coefficient (Dw) etc., indicated that 10% - 30% PVC coatings performed well in comparison to higher PVCs. Changes in the electrochemical characteristics were found to occur as a function of exposure time in all cases. The corrosion stability of the coatings were found to be greatly affected by the percentage of PVCs. Studies further indicated that when lower concentration of pigments were available, they remained completely surrounded by the binder;Thus leaving no space for the entry of corrosive agents. From these studies, it was concluded that the water borne paints could replace the conventional coatings, containing organic solvents. Therefore, water soluble epoxy-ester primers have to be employed in paints for developing eco- friendly coatings.展开更多
In this paper, strontium aluminate phosphors of Sr Al2O4: Eu2+, Dy3+ and Sr4Al14O25: Eu2+, Dy3+ were prepared via solid state reactions and subsequent surface modification with Si O2 by a chemical precipitation method...In this paper, strontium aluminate phosphors of Sr Al2O4: Eu2+, Dy3+ and Sr4Al14O25: Eu2+, Dy3+ were prepared via solid state reactions and subsequent surface modification with Si O2 by a chemical precipitation method. The strontium aluminate phosphors were characterized by measurement-ray diffraction. According to the analysis by transmission electron microscopy, a continuous Si O2 coating layer with a thickness of 50 nm can be formed on the surface of Si O2-coated phosphor. The covalent bond that attached the phosphor and the Si O2 coating was determined by Fourier transform infrared spectroscopy. The water resistance and optical measurements indicate that the optimum ratio of Si O2 coating to phosphors is 30% by mass. Also, the Si O2-coated phosphors could be used in a water-borne paint with the superior luminous performance.展开更多
文摘The corrosion behavior of water borne epoxy-ester primer coatings (10% - 50% PVCs) was evaluated through electrochemical techniques such as polarization and impedance spectroscopic (EIS) measurements. Studies were carried out for a longer duration of exposure extending up to 60 days in aqueous solution of NaCl (5%). Corrosion current (icorr), Corrosion potential (Ecorr), Coating resistance (Rc), Charge transfer resistance (Rct), Coating capacitance (Cc), Double layer capacitance (Cdl), break point frequency (fb), Water uptake (∮), diffusion coefficient (Dw) etc., indicated that 10% - 30% PVC coatings performed well in comparison to higher PVCs. Changes in the electrochemical characteristics were found to occur as a function of exposure time in all cases. The corrosion stability of the coatings were found to be greatly affected by the percentage of PVCs. Studies further indicated that when lower concentration of pigments were available, they remained completely surrounded by the binder;Thus leaving no space for the entry of corrosive agents. From these studies, it was concluded that the water borne paints could replace the conventional coatings, containing organic solvents. Therefore, water soluble epoxy-ester primers have to be employed in paints for developing eco- friendly coatings.
基金financially supported by the Bayer-Tongji Eco-Construction and Materials Academythe open Funds from the Key Laboratory of Advanced Civil Engineering Materials (Tongji University)
文摘In this paper, strontium aluminate phosphors of Sr Al2O4: Eu2+, Dy3+ and Sr4Al14O25: Eu2+, Dy3+ were prepared via solid state reactions and subsequent surface modification with Si O2 by a chemical precipitation method. The strontium aluminate phosphors were characterized by measurement-ray diffraction. According to the analysis by transmission electron microscopy, a continuous Si O2 coating layer with a thickness of 50 nm can be formed on the surface of Si O2-coated phosphor. The covalent bond that attached the phosphor and the Si O2 coating was determined by Fourier transform infrared spectroscopy. The water resistance and optical measurements indicate that the optimum ratio of Si O2 coating to phosphors is 30% by mass. Also, the Si O2-coated phosphors could be used in a water-borne paint with the superior luminous performance.