| 引用本文: | 杨焜,邓子谦,牛少鹏,徐丽萍,曾威,戴红亮,宋进兵.低压等离子喷涂CoNiCrAlY粉末颗粒沉积行为及涂层性能[J].中国表面工程,2024,37(5):361~372 |
| YANG Kun,DENG Ziqian,NIU Shaopeng,XU liping,ZENG Wei,DAI Hongliang,SONG Jinbing.Splat-deposition Behavior and Coating Properties of Low-pressure plasma-sprayed CoNiCrAlY Powder[J].China Surface Engineering,2024,37(5):361~372 |
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| 摘要: |
| 低压等离子喷涂 MCrAlY 涂层具有优良的抗高温氧化和热腐蚀性能，广泛应用于涡轮发动机热端部件的防护，但对于喷涂过程中单个熔融 MCrAlY 粉末颗粒的沉积及堆叠过程与涂层结构及性能之间的关联仍不够清晰。采用低压等离子喷涂方法，在镍基高温合金 GH3536 基体及抛光涂层表面收集 CoNiCrAlY 扁平颗粒沉积物及厚度数百微米的涂层，并对单个及堆叠扁平颗粒沉积物的形貌以及涂层的微观结构和性能进行表征。结果表明，喷涂腔室内保护气氛压强降低时， 熔融的 CoNiCrAlY 粉末颗粒在基体表面快速铺展并凝固沉积为边缘存在一定数量溅射物的扁平化盘状物，而熔融粉末颗粒在已沉积涂层表面铺展得更为充分，大量充分熔化并铺展的扁平颗粒沉积物以机械咬合的方式相互结合并逐层堆垛形成致密涂层。涂层的孔隙率可控制在 1%以内，氧含量低至 0.32%，结合强度 75 MPa 以上，涂层经真空热处理后在 1 050 ℃ 时达到完全抗氧化级别，真空热处理还可提高涂层的组织均匀性以及涂层的内聚强度，并在涂层与基体界面处形成厚度数十微米的互扩散层，进一步改善涂层与基体的结合强度。低压等离子喷涂 CoNiCrAlY 厚涂层的组织均匀致密、综合性能优良，与单个熔融粉末颗粒在基体及已沉积涂层表面的沉积堆垛行为密切相关。研究结果可为基于对熔融粉末颗粒沉积堆叠行为调控以实现涂层结构和性能优化提供依据。 |
| 关键词: 低压等离子喷涂 钴镍铬铝钇 沉积行为 微观结构 涂层性能 |
| DOI：10.11933/j.issn.1007-9289.20220519001 |
| 分类号:TG174 |
| 基金项目:广东特支计划（2019BT02C629）；广州市科技计划（202007020008） |
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| Splat-deposition Behavior and Coating Properties of Low-pressure plasma-sprayed CoNiCrAlY Powder |
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YANG Kun1，2，3，DENG Ziqian1，2，3，NIU Shaopeng1，2，3，XU liping1，2，3，ZENG Wei1，2，3，DAI Hongliang1，2，3，SONG Jinbing1，2，3
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1.Institute of New Materials, Guangdong Academy of Sciences, Guangzhou 510650 , China ；2.National Engineering Laboratory of Modern Materials Surface Engineering Technology, Guangzhou 510650 , China ；3.Guangdong Provincial Key Laboratory of Modern Surface Engineering Technology,Guangzhou 510650 , China
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| Abstract: |
| Low-pressure plasma-sprayed MCrAlY coatings exhibit excellent high-temperature oxidation resistance and hot corrosion resistance and can be used as high-temperature sealing coating materials, which are widely used to protect the hot-end components in turbine engines. Meanwhile, thermally sprayed coatings are formed on a substrate by the impingement of fully or partly melted feedstock particles, where the next layer is deposited on top of the previously deposited layer until the desired coating thickness is achieved. Therefore, the flattening nature of the molten particles on the substrate or previously deposited coating during thermal spraying is vital to the coating process. However, the relationship between the flattening behavior of individual molten MCrAlY particles and the stacking behavior of subsequently deposited particles with the coated structure, as well as the performance during low-pressure plasma spraying remain unclear. In this study, commercially available CoNiCrAlY powders manufactured via gas atomization are thermally sprayed onto nickel-based superalloy GH3536 substrates via low-pressure plasma spraying. Individual splat depositions are realized on the mirror-polished superalloy substrate and previously deposited CoNiCrAlY coating specimens. A steel slit featuring a hole with a diameter of approximately 10 mm is installed between the plasma torch and substrate to obtain particles with homogeneous thermal and velocity, as well as to avoid the effects of substrate-temperature increase and the accompanying change in substrate topography induced by the heating flow of the plasma jet. Following splat acquisition, a CoNiCrAlY coating with a thickness of several hundred micrometers is sequentially deposited on a blast-treated superalloy substrate. The top and bottom surface morphologies of individual splats and stacked deposits, as well as the microstructure and properties of the coatings, are evaluated systematically. The results show that when spraying is conducted under a reduced ambient pressure, the individual molten CoNiCrAlY particle spread rapidly on the surface of the substrate and solidify into a disk-shaped splat. During the spreading of the molten droplets, the desorption of the adsorbed gas condensation due to temperature increase at the collision zone between the molten droplet and substrate surface, together with the entrapped gas during the in-flight process of the molten particle, aggregated at the bottom of the flattening droplet. Subsequently, the gathered gas escaped from the edge of the flowing deposition on the substrate surface and formed a few short splashing fingers connected to the central core. Owing to the good wetting performance of the similar materials, the subsequent molten particles spread more extensively on the surface of the previously deposited coating. Numerous fully melted and sufficiently flattened splat deposits combined with each other via mechanical interlocking and stacked layerwise to form a dense coating. The porosity of the coating obtained under reduced ambient pressure can be controlled to less than 1%, the oxygen content of the coating is about 0.32%, the adhesion strength exceeds 75 MPa, and the vacuum-heat-treated coating exhibits favorable antioxidation resistance at 1 050 °C. Vacuum heat treatment can improve the microstructural uniformity and cohesive strength of the coating as well as enable the formation of an interdiffusion layer with a thickness of several tens of micrometers at the interface between the coating and substrate, thus further improving the bonding strength between the coating and substrate. The performance of the coating satisfies the technical requirements of protective coatings used for hot-end components in turbine engines. In summary, the low-pressure plasma-sprayed thick CoNiCrAlY coating exhibits a uniform and dense structure and excellent comprehensive properties, which are closely related to the flattening behavior of single molten particles on the substrate and the stacking process of the previously deposited coating. The results provide a basis for the optimization of coating structures and performances by controlling the flattening and stacking behaviors of thermally sprayed particles. |
| Key words: low pressure plasma spray CoNiCrAlY deposition behavior microstructure coating property |
