Thermal Properties and Thermal Shock Resistance of γ‐Y₂Si₂O₇

Abstract

Thermal properties, namely, Debye temperature, thermal expansion coefficient, heat capacity, and thermal conductivity of γ‐Y2Si2O7, a high‐temperature polymorph of yttrium disilicate, were investigated. The anisotropic thermal expansions of γ‐Y2Si2O7 powders were examined using high‐temperature X‐ray diffractometer from 300 to 1373 K and the volumetric thermal expansion coefficient is (6.68±0.35) × 10−6 K−1. The linear thermal expansion coefficient of polycrystalline γ‐Y2Si2O7 determined by push‐rod dilatometer is (3.90±0.4) × 10−6 K−1, being very close to that of silicon nitride and silicon carbide. Besides, γ‐Y2Si2O7 displays a low‐thermal conductivity, with a κ value measured below 3.0 W·(m·K)−1 at the temperatures above 600 K. The calculated minimum thermal conductivity, κmin, was 1.35 W·(m·K)−1. The unique combination of low thermal expansion coefficient and low‐thermal conductivity of γ‐Y2Si2O7 renders it a very competitive candidate material for high temperature structural components and environmental/thermal‐barrier coatings. The thermal shock resistance of γ‐Y2Si2O7 was estimated by quenching dense materials in water from various temperatures and the critical temperature difference, ΔTc, was determined to be 300 K.

Thermal properties of single-phase Y2SiO5

“…The calculated minimum thermal conductivities of silicon carbide and selected EBC/TBC candidates are listed in Table 2, 5,[32][33][34]37 wherein Y 2 SiO 5 shows a low value of 1.13 W/m K, being close to the measured minimum value of 1.34 W/m K.…”

Preparation, microstructure and high temperature performances of porous γ-Y2Si2O7 by in situ foam-gelcasting using gelatin

“…In this work, Components 1 and 2 are the dense γ-Y 2 Si 2 O 7 ceramic and air, respectively. The thermal conductivities of dense γ-Y 2 Si 2 O 7 ceramic and air are 4.91 and 0.026 W/(m K), respectively, at room temperature [17]. The d i parameter is related to the number of Euclidean dimensions and sphericity of the dispersed phase, which is taken as d i ¼ 3 in most common approaches.…”

“…Yttrium disilicate (γ-Y 2 Si 2 O 7 ) is a promising refractory ceramic with a high melting point of 1775 1C, good damage tolerance, outstanding chemical and thermal stability, good corrosion resistance, and very low thermal conductivity [o 2 W/(m K) above 1000 1C] [15][16][17][18]. Furthermore, γ-Y 2 Si 2 O 7 is very stable in high-pressure steam at elevated temperatures and retains phase stability up to 1535 7 10 1C [19].…”

Concentration and Cyrstalline Phase Effects on the Spectroscopic Properties of Sol-Gel Synthesized Er³⁺:Y₂Si₂O₇ Nanopowders

“…It shows y, α, β, γ, and δ phases because of complex polymorphism resulting in comparative broad emission [11][12]. It is very difficult to obtain a pure phase of yttrium disilicate because of its intricate polymorphous structure.…”