The Study Of Mechanic And Thermal Properties Of Modified Thermal Barrier Coating

With the development of current industry, the working temperature of engine has been creasing and it requires better high temperature material and cooling technology. After more than 40 years of evolution, applying thermal barrier coating on the high temperature material to lower the substrate working temperature has been mature and applied widely. As to the high working temperature, it's hard to test the temperature and stress distribution during the warming and cooling period. Therefore the experiments and finite element method are both used to obtain the temperature and stress distribution, also the crack expanding analysis and HCPEB modifying TBC analysis. Meanwhile the process of HCPEB on coating surface is analyzed to lay the foundation for the thermal barrier coating invalidation research.After manufacturing the samples through Air Plasma Spray, it goes through high temperature test to gain the dynamic curve. During the high temperature test, the TGO thickness of original and modified TBC and coating morphology are observed. The thermal cycle test is under work spontaneously to view the crack initiation, expanding and connection.By using Abaqus software, TGO growth and temperature and stress distribution are simulated and the fracture strength factors are calculated. Meanwhile the modification process of HCPEB on coating surface is simulated.The results show that TGO growth falls into 3 stages: TGO thickness increases linearly from the beginning to the 10h; stationary stage lasts from 12 h to 192h; the third stage sustain from 192 h to 240 h. Compared with the original TBC, the modified TBC has fewer defects and cavities and the bonding power is stronger, which could slow the TGO expanding speed and lead to finer oxides distribution, finally improving the TBC usage time. Meanwhile, the crack under thermal cycle test grows and the maximum size could reach 20?m. As to the ceramic coating, the dominant factor of crack expanding is tensile load, changes to shear load and finally return to tensile load. As to the bonding coating the leading factor of crack expanding is always tensile load. The modification simulation shows that with the outer energy increasing, the temperature peak appears at the surface and the residual stress on the surface is 40 MPa.