K. Ogawa, Tohoku University, Sendai, Japan
The subcommittee on superalloys and coatings, for The Society for Materials and Science, Japan was established in 1997. For the committees’ second stage work, we recommenced a fundamental study on thermal barrier coatings (TBCs). In this study, we would like to introduce our activities. In particular, relationships between coating conditions and coating properties were discussed. We used 4 spraying conditions such as; 1) standard condition, 2) larger particle used and lower velocity, 3) normal particle used and lower velocity, and 4) standard condition and heating up the substrate to 200 oC. Each sample was sprayed by one of the above conditions, and evaluated in a round robin test. Porosity ratio, residual stress, and bonding strength etc. were evaluated by several techniques for the specimens. As a result, we indicate some recommendations for evaluation of fundamental properties of the plasma sprayed TBCs.
Summary: The subcommittee on superalloys and coatings, The Society for Materials and Science, Japan (JSMS) was established in 1997. As second stage of the committee, we investigated a fundamental study on thermal plasma sprayed thermal barrier coatings (TBCs). Especially, relationships between coating conditions and coating properties are discussed. It was used 4 spraying conditions such as 1) standard condition, 2) larger particle used and lower velocity, 3) normal particle used and lower velocity, and 4) standard condition and heating up the substrate to 200 oC. As a round robin test, porosity ratio, residual stress, and bonding strength were evaluated by several techniques for the specimens, which were sprayed by above 4 conditions. As a result, Young’s modulus, and tensile strength increased with decreasing porosity ratio. In case of tests for residual stress evaluation, as-sprayed specimens have small tensile residual stresses. After thermal exposure, residual stresses shifted to compressive.
Finally, some recommendations were proposed to evaluate these physical and fundamental properties of plasma sprayed thermal barrier coatings (TBCs).
