Effect of rare-earth dopant (Sm) concentration on total hemispherical emissivity and ablation resistance of ZrB2/SiC coatings

被引:41
作者
Tan, Winnie [3 ]
Adducci, Mitchell [1 ]
Petorak, Christopher [2 ]
Thompson, Brian [2 ]
Brenner, Anneliese E. [1 ]
Trice, Rodney W. [1 ]
机构
[1] Purdue Univ, W Lafayette, IN 47907 USA
[2] Praxair Surface Technol Inc, Indianapolis, IN 46222 USA
[3] Siemens Energy Inc, Charlotte, NC 28273 USA
关键词
Emissivity; Hypersonic; Samarium; Zirconium diboride; Ablation; SPECTRAL EMITTANCE; SILICON-CARBIDE; OXIDATION; BEHAVIOR; OXIDES; AIR;
D O I
10.1016/j.jeurceramsoc.2016.04.013
中图分类号
TQ174 [陶瓷工业]; TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
The temperature of leading edges during hypersonic flight can be reduced by maximizing the emissivity of their surface. In this study, the concentration of a known emissivity modifier (Sm) has been varied (3, 5, and 8 mol% Sm in ZrB2/SiC coatings) and the total hemispherical emissivity and ablation resistance of the coatings has been evaluated. Maximum emissivity was observed to occur for the 5 mol% Sm ZrB2/SiC coating, with a value of 0.9 measured at 1600 degrees C. All the ablated Sm-doped coatings have an oxide scale consisting of m-ZrO2 and c(1)-Sm0.2Zr0.9O1.9, and/or Sm2Zr2O7 depending on the Sm concentration. Large amounts of porosity were observed in the oxide scale of the ablated 8 mol% Sm ZrB2/SiC coating. This was attributed to viscosity reduction of the B2O3 and SiO2 glassy phases by the Sm3+ and their subsequent vaporization. The 5 mol% Sm-doped ZrB2/SiC demonstrated the optimal emissivity properties and dense oxide scale formation. (C) 2016 Elsevier Ltd. All rights reserved.
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页码:3833 / 3841
页数:9
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