Study On Thermal Shock Resistance Of The Ceria-based Infrared Low Emissivity Coatings(IRLEC)with High Temperature Resistance

The application of infrared low emissivity coatings with high temperature resistant on aircraft engine hot-section components is an effective measure to shorten the identified distance and reduce the infrared radiation. Ceria-based coatings have good heat resistance performance and low infrared emissivity in 3~5?m waveband at high temperature. However, the performance of thermal shock resistance is comparatively poor at 800?. In this thesis, in order to improve thermal shock resistance of ceria-based coatings at 800?, the ceria-based infrared low emissivity coatings of high thermal shock resistance were prepared by the means of adding additives and modifying agents. Furthermore, the comprehensive performance of optimal thermal shock resistance coatings was researched.The obtained research results were as follows:1. Adding a certain content of magnesium oxide can reduce the difference of thermal expansion coefficient of ceria-based coatings and substrates and improve the thermal shock resistance of coatings. However, the thermal expansion coefficient does not play a major role in thermal shock resistance of coatings when the content is too large.2. Lithium bentonite, as a suspension assistant of coatings, can solve the issue of cerium oxide packing sinking and enhance the interface bonding of adhesive on the substrate, which improves the thermal shock resistance and decreases the infrared emissivity of coatings.3. The issue of packing accumulation can be solved by modifying the cerium oxide, making the filler dispersed evenly in the adhesive, avoiding foaming or cracking phenomenon of coatings and preventing packing from sinking, which can increase the thermal shock resistance and lower the infrared emissivity of coatings.4. In this thesis, the performance of thermal shock resistance of the coating, with 66% of cerium oxide, 3% of magnesium oxide, 1% of lithium base bentonite and 30% of silicate binder, is the most excellent, the times of which is fifty-two. Meanwhile, the infrared emissivity of this coating at 600? is 0.367, and the coating also has good adhesion, high temperature resistance, oxidation resistance and wet and heat resistance.