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Preliminary study on suspension plasma sprayed ZrO2+8 wt. % Y2O3 coatings

pubblicazioni - Articolo

Preliminary study on suspension plasma sprayed ZrO2+8 wt. % Y2O3 coatings

ZrO2+8wt.%Y2O3powderofameandiameterdVS=38um was milled to obtain fine particles having mean size of dVS=1um. The fine powder was used to formulate a suspension with water, ethanol and their mixtures. The zeta potential of obtained suspensions was measured and found out to be in the range from−22to−2mV depending on suspension formulation. The suspension was injected through a nozzle in to plasma jet and sprayed onto stainless steel substrates. The plasma spray experimental parameters included two variables: (i) spray distance varying from 40 to 60 mm and (ii) torch linear speed varying from 300 to 500 mm/s. The microstructure of obtained coatings was characterized with scanning electron microscope (SEM) and X-ray diffraction (XRD). The coatings had porosity in the range from 10% to 17% and the main crystal phase was tetragonal zirconium oxide. The scratch test enabled to find the critical load in the range of 9-11 N. Finally ,thermal diffusivity of the samples at room temperature, determined by th-rmographic method, was in the range from 2.95×10−7 to 3.79×10−7m2/s what corresponds to thermal conductivities of 0.69 W/ (mK) and 0.97W/ (mK) respectively.

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