Study On Room-Temperature Curing And Properties Of Low Emissivity Coatings In 3~5?m Waveband With High Temperature Resistance

With the development of the infrared detection technology,the low infrared emissivity and hightemperature resistant inorganic silicate coatings,which are coated on the air-turbine combustor of the aircraft,have attracted more and more attentions due to their excellent comprehensive property.The inorganic silicate coatings prepared early in our research group have good thermal shock resistance and low infrared emissivity performance.But they could not be used on surface of the large aircraft for engineering application due to the high curing temperature?120??.Hence,in this paper,the curing agent,CeO₂ size,curing time,the modification and parameter optimization of the silicate binder are researched detailedly.According to the curing mechanism of the silicate coatings to achieve the room-temperature curing?35??of the coatings and still contain good comprehensive performance.The obtained researching works and results are as follow:1.It is pointed out that the low chemical cross-linking degree and residual water in coatings lead to the poor performance of the room-temperature curing coatings,according to the theoretical and experimental analysis.2.Studying on the coatings added sodium fluosilicate,aluminium triphosphate,aluminium chloride hexahydrate respectively.The results indicate that the thermal shock resistance and adhesion of the coatings added curing agent are improved due to the increasing of the chemical cross-linking degree.At the same time,the coatings still keep low infrared emissivity property in 3⁵?m waveband.3.The physical water loss of the room-temperature curing coatings is adjusted by CeO₂ size and curing time.The results show that,the velocity and gross of the losing water in coatings and the infrared emissivity?3⁵?m?of the coatings decrease since the decreasing of the porosity and macros-pore ratio.The water loss process stops after 3days in room-temperature,the performance of the coatings reaches to the best and tends to be stable after 7days.4.The ⁶⁰Co-? ray irradiation method is used to modify the inorganic silicate.The microscopic change of the irradiated inorganic silicate and the macro-properties of the coatings show that,these measures can eliminate the aging of the binder by refining colloidal particles in the silicate binder and improve the cross-liking degree of the coatings,which can make a good performance of the coatings.5.The room-temperature curing silicate binder is optimized by orthogonal experiment.The best optimized parameters show that the modulus value,baume degree,viscosity,irradiation dose of the optimized silicate binder are 3.0,46°Be,167mpa·s and 50 kGy respectively.The cross-linking degree of the coatings is 83.31%,the thermal shock resistance of the coatings cooling at room temperature from 800? is 55 times and the adhesion is grade 2.At last,the comprehensive performance of the coatings are compared with those of the coatings curing at the other two curing conditions.