Synthesis of NiCr2O4 spinel coatings with high emissivity by plasma spraying

Air plasma spraying (APS) was used to produce high emissivity coatings with a NiCr2O4 spinet structure. The relationship between the emissivity and the crystal structure was investigated. X-ray diffraction (XRD) analyses show that NiCr2O4 spinet has been fabricated with the space group Fd3m. Scanning electron microscope (SEM) photographs show that the coating consists of a laminated structure with homogeneous grains and high porosity because of the unique feature of plasma spraying. The emissivity measurement and Fourier transformation infrared radiation (FT-IR) spectra show that NiCr2O4 has a high emissivity of about 0.91 because of its special spinel structure. APS is a suitable method to produce high emissivity coatings.