Oxidation performance of CNT-reinforced Cr₃C₂-NiCr coatings sprayed by HVOF method

Abstract

The high-temperature oxidation performance of thermal sprayed nanocomposite coatings is discussed in the present study. The three combinations 3, 5, and 7% wt. of CNT reinforced Cr₃C₂-25% NiC coatings sprayed by HVOF on SAE-213 T12 boiler tube alloy steel working at 6000C in silicon tubular furnace following 1hour heating and 20 minutes cooling in atmospheric temperature for 50 cycles. Thermally developed oxidized layer formation influences in structural variations on surface morphology, phases of elements of uncoated and CNT coated sample were analysed using SEM/EDS and XRD techniques. The thermogravimetric approach was used to estimate the kinetics of oxidation on all samples the weight gain measurement has been studied. The weight accumulation of bare substrate has a higher rate of oxidation than the CNT coated samples. The weight gain of the samples oxidation mechanism generally represents parabolic in nature. The oxidation growth rate minimizes when CNT reinforced in coatings and oxidizing scale deposited on CNT coated surface significantly lower than uncoated samples. The developed Cr₂O₃, NiO, and Fe₂O₃ oxidized layers were provided intensifying oxidation resistance.