Study On Preparation Of Novel Thermal Barrier Coatings With Ta/Zr System And Effect Of Vapor Pressure And Surface Energy And The Effect Of Steam Pressure And Surface Energy

Thermal Barrier Coatings(TBCs)are Thermal insulation materials with sufficient thickness and durability.The application environment of TBCs is complex,with high temperature,corrosion and high pressure on the exterior and high thermal stress on the interior due to the different physical properties between adjacent layers.At present,6?8 wt.%yttrium oxide stabilized zirconia(6?8YSZ)is a widely used TBCs material,which has attracted much attention due to its low thermal conductivity and excellent mechanical properties.Due to YSZ's high temperature phase transition properties,the application temperature is limited,so the development of a new material thermal barrier coating is urgent.The new thermal barrier coating materials require higher operating temperature,environmental stability and excellent phase stability In 2007,Professors Clarke and Levi proposed that yttrium tantalate could be a new generation of thermal barrier coating material.Based on this,this paper studies the preparation process of new tantalum-zirconium series coating and discusses the influence of vapor pressure and surface energy on YTaO₄coating through theoretical calculation.The main research contents and results are as follows:(1)With atmospheric plasma spraying method two ingredients of tantalum zirconium ceramic coating was prepared,from spraying powder preparation has carried on the exploration to the concrete spraying parameters settings,finally in nickel base alloy substrate preparation is about 100 microns thick success of tantalum zirconium ceramic coating,the other is divided into m-YTaO₄ and t-Zr O2,macroscopic surface level off,was lower than those of YSZ coating porosity,The interface morphology is laminated,the element distribution is uniform,and there is no obvious pore.At the same time,the physical vapor deposition process was used to prepare the substrate.By adjusting the substrate speed and temperature,the controlled variable experiments were carried out.It was concluded that the substrate temperature had a significant effect on the phase composition,and the phase composition with good crystallinity could be obtained in the range of 850-950°C.In the range of 4-22r/min,the smaller the size of columnar grains,the tighter the columnar clearance.(2)The Y-O,Ta-O and Ta-Y binary systems were evaluated by thermodynamic calculation and phase diagram calculation method.The experimental data and thermodynamic data collected were used to optimize the Ta-O binary system,and the self-consistent thermodynamic parameters were obtained.Based on the thermodynamic parameters of the above three binary systems,the thermodynamic database of Y-Ta-O system was extrapolated,and the isothermal cross section of Y-Ta-O system at different temperatures and the changes of steam components of Y and Ta with temperature and pressure were calculated,and the change trend of steam components with evaporation temperature and system pressure was obtained.The reason of component delamination in EB-PVD coating was explained.(3)The structure of monoclinic M-YTaO₄ phase was optimized by first principles calculation.The atomic displacement changes of(100),(010),(111)and(110)low value surfaces before and after surface relaxation were analyzed.The most stable surface was obtained,which was in good agreement with the results of Materials Studio simulation calculation.The surface morphology of the coating was analyzed theoretically.