Thermal Barrier Coatings: Current Status, Search, and Analysis

The principles for selecting materials to be used as thermal barrier coatings (TBCs) are presented. The advantages and disadvantages of new methods for TBC deposition are briefly described. After measurement of the thermal conductivity and thermal expansion coefficient, it is required to ascertain that such materials do not interact with the thermally grown aluminum oxide and then to determine their strength, fracture toughness, hardness, and Young's modulus. The thermal conductivity of TBC can be reduced by increasing its porosity and suppressing its sintering. The need for and drawbacks of multilayer coatings are shown. If TBC meets all the requirements, then TBC corrosion resistance to Na2SO4, V2O5, P2O5, sand, and volcanic ash in operation and ways to protect TBC against damage need to be determined. The prospects and areas for development of these techniques are outlined.