Properties And Preparation Of Iron Cobalt Based Infrared Radiant Coatings

Energy is an important energy-giving material resource, however, the energy crisis is increasingly serious with the development of human society. Therefore, the reasonable development and utilization of energy become particularly important. In this context, the infrared radiation materials, as a kind of energy-saving materials with the function of photoelectric conversion, has been extensively attracted attention from domestic and foreign researchers. Iron cobalt infrared radiant based materials which possess inverse spinel structure show high infrared emissivity, and this material can also remain the high infrared emissivity at high temperature due to the stability of this spinel structure at high temperature. Hence, it has wide applications and great research significance. Iron cobalt infrared radiant base materials were synthesized by the sol-gel auto-combustion method in this paper. The effect of raw material formula and process parameters on the preparation and properties of the base materials was investigated. Then the right amount of binder was added to prepare infrared radiating coating with high thermal shock resistance on the SUS304 stainless steel substrate. The phase, adhesive force, surface morphology, element distribution, infrared radiation performance and saving efficiency of the infrared radiating coating were studied in detail finally.The sol-gel auto-combustion reaction can be regarded as a redox reaction. The preparation and infrared radiation performance of the CoFe₂O₄ powder was affected by the pH of precursor solution, the type of complexing agent, the amount of citric acid and the heat treatment method of dried gel. The results showed that the best pH of precursor solution was 6, the best complexing agent was citric acid,the best CA/MI was 1:1,and the best heat treatment method of dried gel was precombustion calcined. The CoFe₂O₄ powders prepared in these conditions had good crystallization, small grain size, loose structure, large specific surface area and good infrared radiation performance. The infrared emissivity of the powder was as high as 0.87.The infrared radiating coating with high thermal shock resistance was prepared using the prepared CoFe₂O₄ power as infrared radiant base materials, aluminum phosphate as binder, and copper oxide as curing agent, and the experiment parameters were optimized with orthogonal experiment. The results showed that the best parameters were the glue mixed ratio of 0.7g/ml, copper oxide content of 10wt% and the calcination temperature of 700℃. And the glue mixed ratio was the factor that had the biggest influence on thermal shock resistance of coating. The coating prepared at the best parameters can withstand 32 times thermal shock of cooling in the air from 1000℃. So it had good thermal shock resistance.The phase, adhesive force, surface morphology, element distribution and infrared radiation performance of the infrared radiating coating prepared at the best parameters were studied. The results showed that the phase of the coating included ferrite, aluminum phosphate, aluminum metaphosphate and copper pyrophosphate, and the ferrite with a spinel structure was the main phase. The surface morphology of the coating was compact and rough. The element distribution of the coating was uniform, and the adhesive force of the coating reached the secondary standard of GB/T9286-1998. The infrared emissivity of the coating was 0.90. It had a good infrared radiation performance, which was determined by the phase and surface morphology of the coating.The infrared radiating coating which we prepared had a good application prospect in the field of household kitchen appliance and thermal dissipation. In the field of household kitchen appliance, the energy efficiency was 28.3% in the temperature range of room temperature to 90℃, when we used the stainless steel bowl coated with the infrared radiation coating to heat water. In the field of thermal dissipation, but the energy efficiency of commercially available coating was just 22.6%. The temperature of the stainless steel resistors coated with the infrared radiation coating was 25℃ lower than the empty sample, and 6℃ lower than the resistors coated with commercially available coating when the resistors cooled 5min from 300℃. So the prepared coating has better heat dissipation effect.