On resultant properties of atmospheric plasma sprayed yttria stabilised zirconia coating deposits: designed experimental and characterisation analysis

In this investigation, yttria stabilised zirconia coatings were deposited by atmospheric plasma spray technique under different levels of power, primary gas flowrates, standoff distances, powder feedrates and carrier gas flowrates as prescribed by the central composite rotatable design matrix. The deposition efficiency test and the porosity test were carried out to study the melting state of the feedstock material. The tensile bond strength test, lap shear bond strength test and microhardness test methods were used to evaluate the mechanical properties of coatings. The microstructure analysis was carried out using optical and scanning electron microscopy. The phase analyses were studied by X-ray diffraction. The spray parameters were optimised using multiobjective response surface methodology to maximise deposition efficiency and mechanical properties. The obtained results revealed that the input power is the most predominant factor, which affects the coating deposit quality followed by standoff distance, primary gas flowrate, powder feedrate and carrier gas flowrate. The effects of spray conditions on the coating properties are elaborately discussed in the manuscript.