MICROSTRUCTURE-PROPERTY RELATIONSHIPS in TBCs by USING Different PLASMA Spray Guns

The role of TBC microstructures in contact with deleterious substances is of significant interest to increase the life and reliability of materials used in turbine hot path components. It is of critical interest for advanced applications that materials can be used for temperatures above 1300^oC with improved durability and enhanced performance. Plasma spray processes with their various operating parameters can be considered a flexible technique to carry out appropriate manufacturing of thermal barrier coatings. Air plasma spray (APS) TBC has the porosity in the range of 10%–20%, depending on coating thickness obtained. Generally, coating thickness of 250–400 µm can satisfy the requirement of temperature insulation of 150-200 ºC. This paper reports on microstructural and deposition efficiency investigations dealing with plasma spraying. Diffirent plasma spray guns (F4 and Triplex) were applied in order to obtain suitable microstructures in the TBCs. Plasma spray conditions, coating forming mechanisms, microstructures, phase compositions, of the APS TBCs are discussed. The investigation of microstructures and property relationship are investigated by electron microscophy and XRD methods.