Microstructure and infrared emissivity property of coating containing TiO2 formed on titanium alloy by microarc oxidation

Ceramic coatings containing TiO2 were formed on Ti6Al2Zr1Mo1V alloy surface by microarc oxidation (MAO) method. The microstructure, phase and chemical composition of the coatings were analyzed by SEM, XRD and EDS techniques. The coating mainly consists of rutile TiO2 and a small amount of anatase TiO2. The infrared emissivity values of coated and uncoated titanium samples when exposed to 700 °C were tested. It was found that the coating exhibits a higher infrared emissivity value (about 0.9) in the wavelength range of 8–14 μm than that of the uncoated titanium alloy, although which shows a slight increase from 0.1 to 0.3 with increasing exposure time at 700 °C. The relatively high infrared emissivity value of the MAO coating is possibly attributed to the photon emission from the as formed TiO2 phase.

► A high infrared emissivity coating was fabricated on titanium by microarc oxidation.
► The coating mainly consists of rutile TiO2 and a small amount of anatase TiO2.
► The coating exhibits an emissivity value (about 0.9) in 8–14 μm wavelength.
► The photon emission from TiO2 component enables the relatively high emissivity value.