Comparison Of The Microstructural Characteristics And Electrical Properties Of Plasma Sprayed Al2o3 And Al2o3-Ca2sio4 Coatings Immersed In Deionized Water

In this study, Al2O3 and Al2O3-Ca2SiO4 coatings were deposited by atmospheric plasma spraying technique. Immersion experiments were performed in deionized water for 1 day and 10 days. The composition and microstructure evolutions of pure and composite coatings with immersion time were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). Microhardness, roughness and insulation resistance of as-sprayed and immersed coatings were evaluated. In particular, a temperature of similar to 25 degrees C and various humidity levels (similar to 10% RH, similar to 42% RH, ambient humidity and similar to 95% RH) were applied in the test of electrical resistance. Relationships between mechanical and electrical properties with coating characteristics were discussed. It is shown that the introducing of Ca2SiO4 in Al2O3 coatings can improve the electrical resistivity under low, middle and ambient humidities, especially after 1 day of immersion. Taking into account the insulation resistance values and mechanical properties of the considered coatings, the plasma sprayed Al2O3-5 wt% Ca2SiO4 is perhaps a promising material for industrial applications.