热处理态NiCoCrAlY涂层的抗中性盐雾腐蚀性能

Salt Spray Corrosion Resistance of NiCoCrAlY Coatings after Heat Treatment

通过500 h中性盐雾试验研究了在低膨胀高温合金GH907上低压等离子喷涂(LPPS)的NiCoCrAlY涂层在热处理后的抗腐蚀性能,并与热处理态的LPPS制备的NiCr涂层的抗腐蚀性能进行了对比。结果表明,盐雾腐蚀500 h后,NiCoCrAlY涂层在扫描电镜下可以看到几个无破坏性作用的腐蚀坑,涂层表面仍保持较好的完整性和光洁性,对腐蚀产物的EDS面扫描表明腐蚀产物主要为Al的氧化物,涂层的腐蚀保护等级仅下降到9级;而NiCr涂层的表面出现了较多的腐蚀斑点,涂层的完整性和均匀性均已经被破坏,涂层表面产生了腐蚀裂纹,其腐蚀等级下降到4级。EDS分析表明腐蚀产物主要为Ni、Fe、Co等的氧化物。对比结果表明,NiCoCrAlY涂层表现出比NiCr涂层更强的抗中性盐雾腐蚀性能。

The 500h neutral salt spray resistance of LPPS （Low Pressure Plasma Spray） NiCoCrAIY coating on low expansion superalloy GH907 was investigated and compared with that of LPPS NiCr coating by means of SEM, EDS etc. The results of SEM showed that the NiCoCrAlY coating had few corrosion pits, and remained to be integral and smooth. EDS analysis showed that the corrosion products were Al oxide. The corrosion level was slightly reduced to the 9th. A few corrosion spots were observed, the integrity and uniformity of the NiCr coating were damaged and some cracks appeared in the NiCr coating after testing for 500 h, and the corrosion level was 4^th. The corrosion products were mainly composed of oxides of Ni, Fe, Co, etc. The NiCoCrAlY coating exhibited better neutral salt spray corrosion resistance than NiCr coating.