G. Yan, Y. Ng, Z.J. Ong, J. Zhu, L.T. Chew, C.J.J. Lee, G.W.H. Teh, D.C.C. Tan, C.K.I. Tan, A.C.Y. Ngo, H. Liu, Ceramic coatings on stainless steel substrate by atmospheric plasma spray: Comparisons between Y₂O₃ and YF₃.
Abstract:
Ceramic coatings of Y2O3 (~95 um thick) and YF3 (~75 um thick) were deposited on stainless steel (SS316) coupon substrates under similar conditions by atmospheric plasma spray (APS) for comparing their microstructural properties, anti-wear behaviors, and thermal stabilities. Before APS, the SS316 coupons were sandblasted to an average roughness of Ra = 5.13 um, and the Ra increased to 7.48 and 6.36 um for the Y2O3 and YF3 coatings, respectively. Microcracks were observed in both coatings, exhibiting longer length and lower density in Y2O3 than in YF3. In contrast, a higher porosity was observed in Y2O3 (~5.3%) than in YF3 (~1.4%). Nanoindentation measurements on the cross-section of the ceramic coatings revealed higher hardness of the Y2O3 coating (~5.6 GPa) than that of YF3 (~3.6 GPa), however, both have similar modulus (~110 GPa), leading to higher wear resistance of Y2O3 than YF3 under low external loading (i.e., 1.5 N). Heat treatment at 850 oC in argon gas for 2 h resulted in cracking and peeling of the Y2O3 rather than YF3. However, the peeling-off occurred within the coating rather than at the coating/substrate interface, leading to a continuous and denser layer of ~25 um thick firmly remaining on the SS316 substrate. X-ray diffraction studies revealed significant oxidation of the YF3 coating and the crystallite size of both coatings slightly increased after the heat treatment. These observations could have important implications for exploring Y2O3 and/or YF3 coatings for new functional applications, such as tritium permeation barriers, although dedicated hydrogen-isotope permeation studies are required to validate such applications.
License type:
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Funding Info:
This research / project is supported by the FEAT - Advanced Materials Optimized for Fusion Engineering and Systems (AMOFES)
Grant Reference no. : H25-MSE3527
This research / project is supported by the FEAT - Strategic Tokamak Research for Industrial Deployment, and Energy (STRIDE)
Grant Reference no. : H26-MSE1527
This work was financially supported by the Advanced Materials Optimized for Fusion
Engineering and Systems (AMOFES) program through the project Corrosion-Resistant and
Tritium Permeation-Resistant Coatings for Robust Fusion Reactor Performance (A25
MSE3527-A53WP02) and the Strategic Tokamak Research, Industry, Deployment & Energy
(STRIDE) program through the project Tritium Permeation Barrier Coating on Inner Walls of
Conduits (A26-MSE1527-A53-WP16).