| As a kind of new energy-saving materials, infrared radiant coatings were valued inall kinds of industries and fields. Coatings protected substrate materials, it also improvedthermal efficiency and heating quality of products by strengthening radiative transfer,which reduced the cost and energy consumption.Clinker, clay, ZrSiO4and Fe2O3as basic materials, doping MnO2, Cr2O3, NiO andadding sodium carboxymethyl cellulose, high emissivity gradient coatings were preparedby high temperature solid state reaction method which were used under800℃or higher.The depositing effect was best when water content of slurry was between40%~50%. Thesynergistic effects of Cr2O3/NiO and NiO/MnO2significantly improved associativity andthermal shock resistance. Using air cooling method（600℃room temperature）to testthermal shock resistance, the number of times reached41. After900℃sinteringemissivity of gradient coatings were in the range of0.84~0.94. To further achieve energysaving, coatings without sintering were studied. Sodium silicate as binder, the content ofbinder was4.5%~9%. After950℃sintering emissivity of coatings reached0.94. Thesynergy of Fe2O3and MnO2not only increased associative property, but also significantlyimproved infrared radiation property. Coatings adding sodium silicate reached28timesthermal shock before sintering. The number of thermal shock of coatings withoutsintering reached53times after850℃,900℃,950℃.With good wettability, coatings were combined with metal substrate by mechanicalchimeric and physical-chemical reactions. With the increases of transition metal oxidetype and content, the type and strength of spinel diffraction peaks also increased. Besides,diffraction peaks of glass phase were abated, embodying the gradient distribution ofcomposition. Cr2O3/NiO and NiO/MnO2formed spinel structure, and emissivity wasimproved. Coatings without sintering further realized low carbon and energy-saving, andmet industrial demand, also reflected that doping process improveed emission rate. |
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