Multicomponent high-entropy zirconates with comprehensive properties for advanced thermal barrier coating

Sand corrosion, thermal expansion, and ablation of medium‐ and high‐entropy compositionally complex fluorite oxides

“…While high entropy compositions can reduce thermal conductivity and increase the hardness 31,32,34,40‐43 (beneficial for TBCs), we believe the differences of reactivity between 8YSZ and the CCFOs seen here are not dominantated by an entropy effect, but instead caused by the different concentrations of rare‐earth elements. The reactivity tends to increase with increasing cubic stabilizer concentration.…”

“…32,34,35 It has been demonstrated that these medium-entropy compositions can often outperform their high-entropy counterparts regarding thermal conductivity and mechanical properties. 32,34,35 While several studies have investigated thermally insulative HECs and CCCs, 31,32,34,[40][41][42][43] only a couple of reports investigated the reactivity, 30,44 such as mitigating water vapor induced corrosion. While this new class of HECs and CCCs exhibit attractive reduced thermal conductivities, 31,32,35,43 an analysis of their interaction to molten silicates and high-temperature flame ablation, which are essential to qualify them as potential TBCs, is limited in the literature.…”

A step forward from high-entropy ceramics to compositionally complex ceramics: a new perspective

“…Other oxide systems of significant interests include those with the fluorite [13,23,75,76,84], spinel [29][30][31][32]96], pyrochlore [14,[33][34][35][36][37], and perovskite [24][25][26][27][28] structures.…”

Preparation and Thermal Properties of Rare Earth Tantalates (RETaO4) High-Entropy Ceramics

“…但是， 由于降温过程中 ZrO2 会发生四方→单斜的相 变， 使得 YSZ 的使用温度一般不超过 1200 ℃。 YSZ 独特的铁弹相变，使其具有优异的力学性能，至今 还在广泛应用。因此，寻找新型具有铁弹性的热障 涂层材料代替 YSZ 成为新的研究热点。 有研究表明， RETaO4(其中 RE 为 Y, Nd~Er)是一种潜在的热障涂 层材料，它具有良好的热稳定性，较高的热膨胀系 数，并且存在高温四方相到低温单斜相二级铁弹相 变 [6][7][8] 。然而，RETaO4 的热导率(3.94~1.26 W• m -1 •K -1 , 100~900 ℃) 相 比 于 YSZ (3.02~2.38 W• m -1 •K -1 , 100~900 ℃)还有待降低。 "高熵"是近年来设计材料组分的一种新概念， 是指 4 种或 4 种以上的元素以等摩尔或近等摩尔形 成的多组元单相固溶体 [9][10][11][12] 。最初高熵应用在合金 领域，与传统合金相比，高熵合金表现出优异的力 学性能、 抗腐蚀性和热稳定性等 [13] 。 2015 年 Rost 等 [14] 首次报道了高熵氧化物陶瓷，之后研究人员相继 开发了碳化物 [15] 、硼化物 [16] 、氮化物 [17] 和其他氧化 物 [18] 高熵陶瓷。高熵陶瓷由于巨大的晶格畸变，热 导率会显著降低，这使得高熵理念可以应用于新一 代 热障 涂层 的设计。 Li 等 [19] 制 备的 稀土锆酸盐 (RE2Zr2O7)高熵陶瓷(RE = La, Nd, Sm, Eu, Gd, Y)在 300~1200 ℃范围的热导率可以降低至 1 W• m -1 •K -1 以下。Wright 等 [20] 制备了 9 种不同组分的氧化物 (AO2-δ, A= Hf, Zr, Ce, Y, Yb)高熵陶瓷，由于巨大的 晶格畸变造成声子散射增加，每种组分的陶瓷的热 导率都低于 8YSZ 陶瓷。Zhou 等 [21] 通过大气等离子 喷涂制备的(La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 稀土锆 酸盐热障涂层，以其较高的热膨胀系数和较慢的扩 散速率表现出优异的热稳定性。Ren 等 [22]…”