Preparation And Properties Of High Emissity Coatings For Insulation Tile

Along with the rapid development of the aerospace field, application of hightemperature resistant and high emissivity coating is more and more widely in space. Thethermal protection structure attracts the majority researchers’ attentions because theaircraft will face in severely thermal environment when it crosses the atmosphere. Theouter surface of the structure’ s emissity must be high, it must have a strong radiationwhen it is in high temperature so as to radiate the heat re-radiated to the outsideenvironment. Infrared radiation material has a good application as a high emissivitymaterial in the aerospace field, it can enhance the effect of radiant heat for thespacecraft to achieve the purpose of heat dissipation so as to make sure the spacecraftcan work in the operating temperature range.In this study poss-collosol and borosilicate glass are selected as binders, Al₂O₃,SiC, MoSi₂are selected as the main materials. Then make high emissivity coatings onthe tiles surface and use Co₂O₃, NiO, ZrO₂to modify the coatings through ball milling.In the last make out5kind of system paints, including Mo-Si-Al, Mo-Si-Al-Co,Mo-Si-Al-Ni, Mo-Si-Al-Zr and Mo-Si-Al-Co-Ni-Zr. Then sduty the process ofpreparation by way of dipping and brushing. The insulation tiles must be preprocessedbefore start coating. Coat poss-collosol with different functional groups as transitionlayer so as to strength the binding foce between body and coatings. The coatings aredried by the way of ladder heating after being coating with high emissivity coatings,then it are sintered in high temperature.Different components coatings’ phase structure after been sintered at hightemperature are characterized by XRD test. The effect of different transition coatingsare characterized by SEM. The coatings’ surface morphology after many thermal shocksare characterized by a microscope. Finally, the coating materials’ emissivities are testedby the infrared radiation meter.For the coatings sintered at high temperature, the XRD results show that there areMo（SiAl）₂in the generated phase. It is conducive to the improvement ofhigh-temperature oxidation resistance for the coating materials. When composited withmetal oxides, the generated CoAl₂O₄, NiAl₂O₄and ZrSiO₄are conducive to theimprovement of coating materials’ emissivities. The results for effects of differenttransitions to coatings’ structure show that: the coating materials with POSS-50collosolas the transition has the better thermal shock resistance; The coatings’ temperatureproperties and oxidation resistance with borosilicate glass as binders is better than thatwith poss-collosol as binders. The test results of emissivities show that:5kinds ofsystems synthesis materials’ emissivtity are high, the most highest emissivity can reach up to0.95, most of all, for the Mo-Si-Al-Co-Ni-Zr system sample, emissivity is stablein the range of11²0m and can reach to0.9.