Effect of process parameters on properties of Mn1.5CuFe0.5O4 spinel oxide coatings deposited by spray pyrolysis method

Abstract

One of the critical issues in the lifetime of metallic interconnects is related to their high oxidation rate and Cr diffusion, which negatively affect their performance. In the present study, a novel Fe modified Mn–Cu spinel oxide with the chemical composition of Mn_1.5CuFe_0.5O₄ as protective coating was deposited on the surface of Crofer 22 APU and alumina by the spray pyrolysis method. The effects of different deposition conditions including deposition temperature, spraying speed, and volume of precursor on the properties of deposited spinel coatings were investigated. Scanning electron microscopy characterizations showed that the deposited layer was uniform and non-cracked at the deposition temperature of 400 °C. However, at temperatures of 300 $°C$ and lower, the deposited layers became non-uniform and cracked. Additionally, spraying with speeds of 10 ml/h and lower resulted in uniform and non-cracked coatings, and a higher spraying speed of 15 ml/h caused a nonuniform and cracked layer. Atomic force microscopy measurements proposed that the value of R_a was reduced by increasing the deposition temperature and reducing the spraying speed. X-ray diffraction characterization showed that deposition temperature has affected the phase structure of deposited spinel oxides on both substrates. According to electrical conductivity measurements, deposited layers at higher deposition temperatures with lower spraying speeds showed higher electrical conductivity and lower activation energy. Decreasing the deposition temperature reduced the electrical conductivity of the spinel oxide coatings.