فناوری در رنگ، رنگ دهنده ها و پوشش دهنده ها
سال:1396 | دوره:10 | شماره:2 |تعداد مقالات:6

in corrosion protection study, it is important to develop economically attractive test method for mitigation of corrosion damage of coated structure. Faster predication of protective behavior of any coating is a big challenge for the coating industries. In present work, in-house waterborne anticorrosive coating system was selected for study. The corrosion protection of coating evaluated as per ISO12944-C3-High which includes salt spray (ISO 9227, 480 h) and quick condensation test (ISO6270, 240 h). The exposure period was extended up to 1000 h for further monitoring of deterioration of selected coating system. In view of early predication of coating performance, different accelerated test exposure conditions were designed in laboratory, such as thermal aging in distilled water (50° C and 80° C), chemical immersion (H2SO4 and NaOH), wet-dry cycle and thermal cycling. The corrosion protection properties of coating exposed to ISO 12944-C3-High environment was compared against the lab designed test method using electrochemical impedance spectroscopy (EIS) technique. The deterioration rate of coating was measured by evaluating polarization resistance (Rp), water uptake (w) and break point frequency (Fb). The coated specimens after exposure were also evaluated for loss of adhesion strength. Results showed that thermal aging in distilled water at 80° C is the most severe exposure condition as coating system loses its protective behavior in relatively short period. Prog. Color Colorants Coat. 10 (2017), 93-104© Institute for Color Science and Technology.

several silicate materials were plasma sprayed and characterized by the authors in recent years from the point of view of their chemical and phase compositions, microstructure and mechanical as well as thermal properties. The present work is concerned with selected dielectric properties of these deposits. Synthetic mullite and steatite as well as natural olivine-forsterite were plasma sprayed using the water-stabilized plasma system (WSP® ). The deposits were striped-out, ground and polished to produce samples in form of plates with a smooth surface. Part of samples was later annealed in air. These samples-after coverage by metal electrodes functioning as monoblock capacitors-were tested in the alternative low voltage electric field to measure capacity and loss factor in the frequency range from 200 Hz to 1 MHz. Relative permittivity was calculated from the measured capacity. Volume resistivity was measured in the direct electric field. It is shown that the relative permittivity of as-plasma sprayed silicates is less stable compared to bulk in the whole studied frequency range. However, thermal annealing modifies the structure much closer to the sintered bulk which is also reflected in dielectric properties. Insulating ability of plasma-sprayed silicates with and without annealing is discussed in consequence with chemical changes and phase changes induced by annealing. Prog. Color Colorants Coat. 10 (2017), 105-114© Institute for Color Science and Technology.