材料结构与制备工艺对热障涂层显微组织的影响
Influence of Material Structure and Preparation Technologies on Microstructure of Thermal Barrier Coating
王东生1,2, 田宗军2, 王泾文1, 黄因慧2
点击：3782次 下载：0次
作者单位：(1. 铜陵学院 机械工程系, 安徽 铜陵 244000; 2. 南京航空航天大学 机电学院, 江苏 南京 210016)
中文关键字：等离子喷涂； 激光重熔； 热障涂层； 纳米结构； 组织结构
英文关键字：plasma spraying; laser remelting; thermal barrier coatings; nano-structure; microstructure
中文摘要：以常规和纳米团聚体ZrO2-7%Y2O3陶瓷粉末为原料，采用等离子喷涂和等离子喷涂 + 激光重熔复合工艺在TiAl合金表面制备了常规和纳米结构热障涂层。 用扫描电镜(SEM)分析了粉末结构及制备工艺对涂层显微组织的影响。结果表明：用常规等离子喷涂法制备的陶瓷涂层为典型的层状堆积特征；而用等离子喷涂法制备的纳米结构涂层则由纳米颗粒完全熔化区和部分熔化区组成，呈两相结构。 由于受到激光功率、能量密度、激光作用区温度场分布、陶瓷导热系数和涂层厚度等因素的综合影响，经激光重熔后，涂层呈现出明显的分层结构特征：上部为致密的柱状晶重熔区，下部为残余等离子喷涂区。 由于激光重熔纳米结构涂层重熔区中残余纳米粒子的增韧作用，其晶界强度较高，从而导致断口有相当数量的穿晶断裂，而激光重熔常规涂层重熔区的断口基本是沿晶断裂。
英文摘要：The conventional and nano-structure ZrO2-7wt%Y2O3 thermal barrier coating (TBCs) were fabricated by plasma spraying and plasma spraying+ laser remelting technologies with conventional and nano-structure agglomerated powders on TiAl alloy surface. The effects of material structure and preparation process on microstructure of the coating were studied by SEM. The results show that the as-sprayed conventional ceramic coating has a typical lamellar stacking characteristic. However, the plasma-sprayed nano-structure coating exhibits a bimodal distribution which is composed of a certain percentage of the fully molted and partially melted nano-particles. The laser-remelting coating exhibits obvious layer-like characteristic due to the influence of laser powder, laser energy density, temperature distribution, thermophysical parameters of ceramic and coating thickness. According to the microstructural difference, the ceramic coating can be divided into remelting zone (fine column-like crystals) and remained plasma-sprayed zone (lamellar-like structure). Due to the effect of remained nano-particles on the remelted zone of the laser-remelted nano-structure coating, the toughness and grain boundary strength of the nano-structure coating are higher than the converational coating. And considerable transgranular fractures exist in the fracture of the nano-structure coating. In contrast, the fracture of the traditional coating almost shows ingergranular fracture morphology.