Evaluation of rare‐earth element dopants (Sm and Er) on ablation resistance of ZrB2/SiC‐sintered billets. Issue 9 (25th March 2019)

• Record Type: Journal Article
• Authors: Peña, Angel A.; Vernon, Jonathan P.; Trice, Rodney W.
• Is Part Of: Journal of the American Ceramic Society. Volume 102:Issue 9(2019)
• Page Start: 5645
• Page End: 5655
• Publication Date: 2019-03-25
• Subjects: ablation -- erbium -- hypersonic -- samarium -- Zirconia; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.16422
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: In this paper, how rare‐earth element dopants (samarium and erbium) affect the scale development of sintered ZrB2 /SiC (ZBS) samples during ablation testing was investigated. ZBS billets with five different Sm to Er ratios, with a nominal total amount of 3 mol% dopant incorporated, were prepared by sintering in vacuum to 2000°C and subjected to 60 and 300 seconds ablation cycles. Differences in surface temperatures between ZBS samples with different dopant ratios suggests differences in spectral absorptance/emittance between each of the five compositions investigated. ZBS billets co‐doped with Sm and Er form a beneficial c1 ‐(Sm/Er)0.2 Zr0.8 O1.9 oxide scale as the majority phase, with some glassy phase observed. The crystalline c1 ‐(Sm/Er)0.2 Zr0.8 O1.9 oxide scale is more thermally stable than the m ‐ZrO2 oxide scale typically formed in oxidized ZBS systems, resulting in a more adherent oxide scale to the unreacted material. The crystalline oxide scale and the amorphous phase are formed by a convection cell mechanism where the c1 ‐(Sm/Er)0.2 Zr0.8 O1.9 crystalline islands precipitate, grow, and coalesce.