Dependence of infrared radiation on microstructure of polymer derived ceramic coating on steel

High infrared emissivity ceramic coatings were prepared on 304 steel by pyrolyzing reactions with poly(hydridomethylsiloxane) (PHMS) and Al/Cr2O3 based mixing powders. The effects of pyrolysis temperature, testing temperature and surface roughness on infrared radiation of polymer derived ceramic coating were systematically investigated. The results indicated that the coating pyrolyzed at 800 °C exhibited a slightly higher infrared emissivity value than that of the coating pyrolyzed at 600 °C, which was attributed to the enhancing photon emission caused by the complete conversion of Al to Al2O3 and PHMS pyrolysis into SiO2, together with the introduction of Cr2O3 based mixing powders. The emissivity value in 3–8 μm waveband of the coating was lower about 0.03 at 600 °C compared with 800 °C testing temperature, while the emissivity value was almost the same in 8–20 μm waveband. The high surface roughness of the coating led to a slightly increasing emissivity due to the enhancing infrared absorbance.

► The coatings were formed on 304 steel surface by dipping method.
► It was prepared by pyrolyzing reactions with PHMS and Al/Cr2O3 based mixing powders.
► The effects of surface roughness, pyrolysis and testing temperature were analyzed.
► The 800 °C pyrolyzed coating exhibits a slightly higher infrared emissivity value.
► The high surface roughness of the coating leads to a slightly increasing emissivity.