Synthesized of octahedral cupper chromite spinel for spectrally selective absorber (SSA) coatings

Abstract

In this study, cupper chromite Spinel (CuCr2O4) pigment was synthesized via two-step combustion–calcination procedure. Mixtures of citric acid and glycine were used as fuel and nitrate ions were used as oxidizers. The samples were synthesized at different pHs. The synthesized sample was characterized by x-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and energy-dispersive X-ray spectroscopy (EDX). The X-ray diffraction (XRD) patterns of the samples revealed that the single-phase CuCr2O4 spinel was formed. The SEM results showed that the spinel particles were synthesized in octahedral morphology. Furthermore, pH and amount of fuel have remarkable effect on size of particles. Increasing the pH leads to increasing the size of particles. Also, the size of particles was significantly increased by doubling the amount of fuel. In the next step, the synthesized pigments were used as spectrally selective absorber in solvent-based acrylic coatings. The functional groups of the coatings were identified by the attenuated total reflectance (ATR) analysis. The solar absorptance (αs) and the thermal emittance (εT) of the coatings were determined from the corresponding diffuse reflectance spectra. The optimum selective sample were calculated αs = 0.9 and εt = 0.3.