Solution Precursor Plasma Spray - Thermal Barrier Coatings

Thermal Barrier Coatings

Most current research on SPPS has examined is application to create thermal barrier coatings (TBCs). These complex ceramic/metallic material systems are used to protect components in hot sections of gas turbine and diesel engines. The SPPS process lends itself particularly well to the creation of these TBCs. Studies report the generation of coatings demonstrating superior durability and mechanical properties. Superior durability is imparted by the creation of controlled through thickness vertical cracks. These cracks only slightly increase coating conductivity while allowing for strain relief of stress generated by the CTE mismatch between the coating and the substrate during cyclic heating. The generation of these through thickness cracks was systematically explored and found to be caused by the depositing a controlled portion of unpyrolized material in the coating. Superior mechanical properties such as bond strength and in-plane toughness result from the nanometer sized microstructure that are created by the SPPS process.

Other studies have shown that engineered coatings can reduce thermal conductivity to some of the lowest reported values for TBCs. These low thermal conductivities were achieved through the generation of an alternating high-porosity, low-porosity microstructure or the synthesis of a low conductivity precursor composition with rare earth dopants.