Influence of spraying variables on structure and properties of plasma sprayed alumina coatings

• An experimental statistical design study on the plasma spraying of alumina powder has been carried out.Coating experiments were conducted, using a Taguchi full factorial L16 design parametric approach, to study the effect of four key plasma processing variables on the coating quality, namely, primary gas flow rate, arc current, powder feed rate, and spray distance. Optical microscopy, scanning electron microscopy, XRD, image analysis, and hardness testing were used for characterization. The resulting as sprayed coating characteristics were quantified with respect to roughness, microhardness, porosity, and microstructure. Through statistical calculation (analysis of variance), the parameters that have significant influence on the structure and properties of the coatings were identified and their relative importance and contribution ratios to overall variance were studied. The Taguchi evaluation employed in the present investigation showed that an improvement in the coating properties could be achieved using an optimum combination of variables.

Nyckelord

Alumina

Electric currents

Flow of fluids

Hardness testing

Microhardness

Microstructure

Plasma spraying

Porosity

Powder coatings

Sprayed coatings

Statistical methods

Surface roughness

Analysis of variance (ANOVA)

Taguchi method

Ceramic coatings

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