Abstract No.:

4636

Scheduled at:

Tuesday, May 10, 2016, Room 3C + 3D 12:10 PM
Ceramic Coatings I

Title:

Microstructure and thermal properties of atmospheric plasma sprayed Yb₂Si₂O₇ coatings

Authors:

Kai Li / Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai
X. Zhong^* / Shanghai Institute of Ceramics, Chinese Academy of Sciences, China
Niu Yaran/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China
Huang Liping/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China
Li Hong/ Shanghai University, China
Zheng Xuebin/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China
Ding Chuanxian/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China
Sun Jinliang / Shanghai University, China

Abstract:

In the present work, ultra-high purity Yb2Si2O7 powder was synthesized and atmospheric plasma spray was applied to fabricate Yb2Si2O7 coating. The phase composition and microstructure of the coating were characterized by XRD, FESEM and EDS. Some basic properties of Yb2Si2O7 coating including density, porosity and microhardness were detected. Its thermal stability was evaluated by TG-DTA and heat treatment at 1300-1500oC. The thermal conductivity of the original and heat-treated coatings was measured. The results showed that the as-sprayed coating was mainly composed of crystalline Yb2Si2O7 phase. A small amount of Yb2SiO5 phase and amorphous phase were also presented in the Yb2Si2O7 matrix. The coating had a dense structure combining defects, such as pores, interfaces and microcracks. The TG-DTA result showed that there was almost no mass change for the TG curve, while a sharp exothermic peak in DTA curve, which indicated that the amorphous phase started to crystallize at around 1000oC. The thermal conductivity of the as-sprayed coating decreased with increase in temperature up to 600 and then increased with further temperature rise. The minimum value of the thermal conductivity (at 600 oC) of the as-sprayed coating was about 0.68 W/(m K). The Yb2Si2O7 coating exhibited excellent phase stability at temperatures between 1300 oC and 1500 oC in atmospheric environment. The heat insulation performance of the coating decreased after annealing at 1300 - 1500 oC, while the hardness increased.

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