Preparation And High Temperature Performance Of A Novel Thermosensitive/Ceramic Matrix Composite Thermal Protective Coating

In order to solve the key problems such as rapid growth of TGO（Thermally grown oxide layer）layer and oxidation failure of YSZ（Yttria stabilized Zirconia）based thermal protection coating caused by drastic temperature change,so as to improve the high-temperature oxidation resistance,thermal shock resistance and early warning of coating failure.In this paper,a triple-layer temperature sensitive/ceramic matrix composite thermal protective coating with temperature fluorescence response mechanism:Mo Si₂/YGYZ-RE/YSZ-Ni Co Cr Al YTa was designed and prepared.The microstructure,phase composition and phase structure,temperature sensitive fluorescence properties and high temperature properties of the coating were observed.The bonding layer is Ni Co Cr Al YTa,which is prepared by plasma spraying and laser cladding to realize the coordination and matching between ceramic layer and substrate;The intermediate temperature sensitive layer is plasma sprayed RE（Rare earth）modified YSZ.The condition monitoring of the composite coating is realized by using the temperature sensitive fluorescence characteristics of rare earth ions;the modified surface layer is plasma sprayed 20%Mo Si₂/YGYZ（Molybdenum disilicide doped/Yttria Gadolinium Oxide Ytterbium Oxide stabilized Zirconia）to improve the high temperature oxidation resistance and thermal shock resistance of the thermal protective coating:1.The preparation technology of bonding layer has an obvious impact on the performance of YSZ-Ni Co Cr Al YTa composite thermal protective coating.Plasma spraying technology is more suitable for the preparation of composite thermal protective coating than laser cladding technology,and its thermal shock resistance is nearly twice that of composite thermal protective coating prepared by laser cladding technology.2.（Eu）YSZ powder has high sphericity,uniform particle size,high microstructure density and good coating quality.Five rare earth oxides Europium Oxide（Eu₂O₃）,Dysprosium Oxide（Dy₂O₃）,Erbium Oxide（Er₂O₃）,Terbium Oxide（Tb₂O₃）and Neodymium Oxide The doping of（Nd₂O₃）has similar effects on the microstructure and properties of plasma sprayed YSZ based coatings,and the five rare earth oxide doped coatings are composed of t-Zr O₂;among them,the porosity of Eu₂O₃/YSZ-Ni Co Cr Al YTa coating is the lowest,only 8.807%.3.Among the five temperature sensitive coatings,Eu₂O₃/YSZ-Ni Co Cr Al YTa coating still maintains high fluorescence intensity and long fluorescence life in high temperature environment,and the temperature sensitive fluorescence performance is the best.When the calcination temperature of the temperature sensitive coating is 1100℃,It still has the highest fluorescence intensity and relatively low thermal quenching rate（65%）,and the average fluorescence life after calcination is 2.158ms,which is 1.1～49 times that of the other four coatings;the temperature sensitive coating still has an average fluorescence life of 2.077ms after long-term insulation at 1100℃for 80h.Therefore,Eu₂O₃/YSZ Ni Co Cr Al YTa coating has a better temperature fluorescence response mechanism.4.The composite coating of 20%MoSi₂/YGYZ modified surface has the highest density and the best temperature sensitive fluorescence performance.The phase compositions of three x%Mo Si₂/YGYZ（x=10,20,30）-Eu₂O₃/YSZ-Ni Co Cr Al YTa temperature sensitive/ceramic matrix composite thermal protection coatings are t-Zr O₂and t-Mo Si₂phases,which do not change with the doping amount of Mo Si₂;The existence of x%Mo Si₂/YGYZ（x=10,20,30）modified surface layer has little effect on the fluorescence intensity and fluorescence life of temperature sensitive/ceramic matrix composite thermal protective coating,still maintains the average fluorescence life of 2ms,and has a good temperature fluorescence response mechanism.5.Among the three temperature sensitive/ceramic matrix composite coatings,20%Mo Si₂/YGYZ modified surface has the best high temperature performance.The isothermal oxidation experiment of x%Mo Si₂/YGYZ（x=10,20,30）-Eu₂O₃/YSZ-Ni Co Cr Al YTa temperature sensitive/ceramic matrix composite thermal protection coating shows that when the doping amount of Mo Si₂is 20%,the oxidation weight gain of the coating is only3.7mg·cm^-2,and the growth of TGO layer is the smallest,about 3μm;In 1450℃thermal shock test,M2 thermal protective coating containing 20%MoSi₂has the best thermal shock resistance for 242 times.