Hot corrosion is one of the main destructive factors against thermal barrier coatings (TBCs) applied on gas turbine hot components. In this study, hot corrosion behavior of conventional bilayer and compositionally graded layer (CGL) TBCs in two different micro- and nanostructures was evaluated. For this purpose, nanostructured and micro-Y₂O₃-stabilized ZrO₂ (YSZ) were used as ceramic powder feedstocks. NiCrAlY metallic bond coat was deposited on IN-738LC nickel-based superalloy by air plasma spray (APS). Two groups of compositionally graded layer TBCs consisting three layers of NiCrAlY and YSZ in the weight ratios of 100:0 (bond coat), 50:50 (gradient layer) and 0:100 (top coat) were prepared by air plasma spraying. In one group of CGL-TBCs, micro-YSZ feedstock was used, and in the other one, nanostructured YSZ feedstock was used. Bilayer TBCs consisted of two layers (bond coat and top coat). Micro-YSZ and nanostructured YSZ powder feedstocks were applied for conventional and nanostructured bilayer TBCs, respectively. Hot corrosion studies were performed on the surface of the mentioned four TBC groups in the presence of molten mixture of V₂O₅ + Na₂SO₄ at 900 °C for eight-hour cycles. At each cycle, salt concentration of 4 mg/cm² was used. Microstructural evaluation, elemental and phase analysis were performed using field emission scanning electron microscopy (FE–SEM) and X-ray diffraction (XRD). Based on the results, the hot corrosion resistance of nanostructured bilayer TBC was improved by 2.5 times compared with that of micro one. Furthermore, compositionally graded layer TBCs exhibited superior corrosion resistance compared to the bilayer TBCs. It was also revealed that applying gradient layer TBC compared with nanostructured bilayer, one has greater effect on increasing the hot corrosion resistance of conventional bilayer TBC. Moreover, a combination of compositionally graded layer and nanostructure TBCs resulted in higher corrosion resistance. In addition, hot corrosion mechanisms of nanostructured and micro-TBCs were suggested.

热腐蚀是对应用在燃气轮机热部件上的热障涂层 (TBC) 的主要破坏因素之一。在这项研究中，评估了传统双层和成分渐变层 (CGL) TBC 在两种不同的微米和纳米结构中的热腐蚀行为。为此，纳米结构和微 Y ₂ O ₃稳定的 ZrO ₂(YSZ)用作陶瓷粉末原料。NiCrAlY 金属结合涂层通过空气等离子喷涂 (APS) 沉积在 IN-738LC 镍基高温合金上。通过空气等离子喷涂制备两组成分渐变层TBC，由三层NiCrAlY和YSZ组成，重量比为100:0（粘合层）、50:50（梯度层）和0:100（面漆）。在一组 CGL-TBC 中，使用了微型 YSZ 原料，而在另一组中，使用了纳米结构的 YSZ 原料。双层 TBC 由两层（粘合涂层和面漆）组成。微 YSZ 和纳米结构 YSZ 粉末原料分别应用于常规和纳米结构双层 TBC。在 V ₂ O ₅的熔融混合物存在下，对上述四个 TBC 基团的表面进行了热腐蚀研究 + Na ₂ SO ₄在 900 °C 下进行八小时循环。在每个循环中，盐浓度为 4 mg/cm ²被使用。使用场发射扫描电子显微镜 (FE – SEM) 和 X 射线衍射 (XRD) 进行微观结构评估、元素和相分析。结果表明，纳米结构双层TBC的抗热腐蚀性能比微米层提高了2.5倍。此外，与双层 TBC 相比，成分渐变层 TBC 表现出优异的耐腐蚀性。还表明，与纳米结构双层相比，应用梯度层TBC对提高传统双层TBC的耐热腐蚀性能有更大的影响。此外，成分渐变层和纳米结构 TBC 的组合导致更高的耐腐蚀性。此外，还提出了纳米结构和微型 TBC 的热腐蚀机制。