刘天,孙杰,宋佳,杨国昊,孙海静,王保杰.NiCrAl-NiC封严涂层在盐雾环境下的腐蚀行为研究[J].表面技术,2023,52(1):206-213.
LIU Tian,SUN Jie,SONG Jia,YANG Guo-hao,SUN Hai-jing,WANG Bao-jie.Corrosion Behavior of NiCrAl-NiC Seal Coating in Salt Spray Conditions[J].Surface Technology,2023,52(1):206-213 |
| NiCrAl-NiC封严涂层在盐雾环境下的腐蚀行为研究 |
| Corrosion Behavior of NiCrAl-NiC Seal Coating in Salt Spray Conditions |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.01.021 |
| 中文关键词: NiCrAl-NiC封严涂层 盐雾试验 电化学测试 腐蚀 |
| 英文关键词:NiCrAl-NiC seal coating salt spray test electrochemical test corrosion |
| 基金项目:沈阳理工大学高水平成果建设项目(SYLUXM202105);沈阳理工大学科研创新团队支持项目(SYLUTD202004) |
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| Author | Institution |
| LIU Tian | Shenyang Ligong University, Shenyang 110159, China |
| SUN Jie | Shenyang Ligong University, Shenyang 110159, China |
| SONG Jia | AECC Shenyang Liming Aero-Engine Co., Ltd., Shenyang 110043, China |
| YANG Guo-hao | Shenyang Ligong University, Shenyang 110159, China |
| SUN Hai-jing | Shenyang Ligong University, Shenyang 110159, China |
| WANG Bao-jie | Shenyang Ligong University, Shenyang 110159, China |
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| 中文摘要: |
| 目的 通过盐雾试验，研究NiCrAl-NiC封严涂层在高湿度、高盐分的环境中工作的腐蚀行为及机理。 方法 使用热喷涂的方法，在GH907基体上，以NiAl作为粘结层，喷涂制备NiCrAl-NiC封严涂层，并针对该涂层进行连续盐雾试验。对不同盐雾试验时间得到的试样进行电化学(极化曲线以及电化学阻抗谱)测试、XPS测试、SEM观察及EDS测试，研究涂层的腐蚀行为。结果 在500倍电子显微镜下观察得涂层表面腐蚀在表面孔隙附近发生，且腐蚀产物随腐蚀时间的增加而不断增加。EDS结果显示，腐蚀前期O元素含量增加，在连续盐雾时间达到72 h后，观察到Cl、Fe元素，且涂层表面的腐蚀产物出现裂隙。这个结果说明电解质溶液已侵入涂层内部，使基体发生腐蚀。涂层在盐雾试验前期，极化曲线所得腐蚀电流密度有所下降，说明涂层耐蚀性增强。盐雾腐蚀后期，腐蚀电流密度增加，涂层耐蚀性下降。结论 试验前期，腐蚀产物的积累使得涂层的耐蚀性提高，由于腐蚀速率随时间逐渐增加，试验后期涂层内部已经发生腐蚀，腐蚀产物为金属氧化物和氢氧化物。 |
| 英文摘要: |
| With the development of aero-engine technology, gas path sealing technology plays an important role in the continuous improvement of aero-engine mechanical efficiency. It is widely used due to the advantages of convenient maintenance, simple manufacturing process and good thermal stability of thermal spraying seal coating. When the seal coating is applied in the environment of high humidity and high salt, its composite metal coating will be seriously damaged. Therefore, the work aims to study the corrosion behavior of NiCrAl-NiC seal coating in high humidity and high salt environment by the salt spray test. The NiCrAl-NiC seal coating was prepared by atmospheric plasma spraying. The surface layer of NiCrAl-NiC seal coating was 1.5 mm thick and the bonding layer of NiAl was about 0.15 mm thick. It was sprayed on the GH907 substrate with a thickness of 2 mm by thermal spraying, and the salt spray test was continuously carried out to the coating. The other five sides of the sample were sealed with silica gel to ensure that only one side of the coating was exposed to salt spray. The test was carried out in accordance with GB/T 1012—2012. The solution was analyzed with 5wt.% pure NaCl solution. The test equipment was DCTC1200P salt spray box. The corrosion time of the samples was 96 h. The samples were continuously sprayed for 24 h, and a set of samples was removed every 24 h. The samples obtained after different time of salt spray test were stored in CS350 electrochemical workstation. The three-electrode cell was used (the reference electrode was saturated calomel electrode, the auxiliary electrode was platinum electrode, and the working electrode was the tested sample) to carry out polarization curve test, electrochemical impedance spectrum test, and scanning electron microscope (TESCAN-MIAR4) observation. Then, the energy dispersive spectrometer spectrum of each selected point collected by the energy spectrometer was used to analyze the elements. X-ray photoelectron spectroscopy test was carried out to the samples after 96 h of salt spray corrosion, and the composition of corrosion products was deeply analyzed. It was observed that the coating surface was loose and had many pores under 500 times electron microscopes, and the corrosion occurred near the surface pores. The results of the energy dispersive spectrometer showed that the content of O element increased in the early stage of corrosion. After continuous salt spray time reached 72 h, Cl and Fe elements were observed, and cracks appeared on the corrosion products on the coating surface. This result showed that the electrolyte solution intruded into the interior of the coating, resulting in corrosion of the substrate. The XPS results after 96 h of corrosion showed that the corrosion products were Al2O3, Ni(OH)2, FeOOH, etc. In the early stage of salt spray test, the corrosion current density obtained by polarization curve decreased, indicating that the corrosion resistance of the coating was enhanced. In the later stage of salt spray corrosion, the corrosion current density increased and the corrosion resistance of the coating decreased. The accumulation of corrosion products in the early stage of the test improves the corrosion resistance of the coating. Due to the gradual increase of corrosion rate with time, corrosion has occurred in the coating in the later stage of the test, and the corrosion products are metal oxides and metal hydroxides. |
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