Inferior fracture toughness (KIC), low thermal expansion coefficient (CTE), thermochemical incompatibility with bond coat and growth of thermally grown oxide (TGO) are the main destruction factors in conventional Gd2Zr2O7 (GZO) thermal barrier coating (TBC) undergoing thermal cycling. In this paper, to overcome these drawbacks, nanostructured GZO and an intermediate conventional YSZ layer between top and bond coats were used in the TBC system. Single-layer nanostructured GZO and dual-layer YSZ/nanostructured GZO coatings were deposited with atmospheric plasma spray technique on Ni-based superalloy (IN738LC) substrates as a topcoat with a CoNiCrAlY bond coat. Oxidation behaviour of samples was studied and compared in the cyclic mode at 1100 °C for 4 h in each cycle. Also, CTE and KIC of the nanostructured GZO and intermediate YSZ layers were investigated. The results indicated that the oxidation life of dual-layer YSZ/nanostructured GZO coating was 3.2 times more than that of single-layer nanostructured GZO. The microstructural analysis indicated that the growth rate of TGO was considerably slower for dual-layer coating due to reduced oxygen infiltration and cracks propagation. Also, nanostructured topcoat improved the thermochemical compatibility and mechanical properties in TBCs.

中文翻译：

---

YSZ/纳米结构Gd2Zr2O7 TBC热循环的热耐久性

较差的断裂韧性 (KIC)、低热膨胀系数 (CTE)、与粘合涂层的热化学不相容性和热生长氧化物 (TGO) 的生长是传统 Gd2Zr2O7 (GZO) 热障涂层 (TBC) 经历热循环的主要破坏因素。在本文中，为了克服这些缺点，在 TBC 系统中使用了纳米结构的 GZO 和介于顶层和粘合层之间的中间传统 YSZ 层。使用大气等离子喷涂技术将单层纳米结构 GZO 和双层 YSZ/纳米结构 GZO 涂层沉积在 Ni 基高温合金 (IN738LC) 基材上，作为带有 CoNiCrAlY 粘合涂层的面漆。在循环模式下研究和比较样品的氧化行为，在 1100 °C 下每个循环 4 小时。还，研究了纳米结构 GZO 和中间 YSZ 层的 CTE 和 KIC。结果表明，双层YSZ/纳米结构GZO涂层的氧化寿命是单层纳米结构GZO涂层的3.2倍。微观结构分析表明，由于氧气渗透和裂纹扩展减少，双层涂层的 TGO 生长速度显着减慢。此外，纳米结构的面漆改善了 TBC 的热化学相容性和机械性能。