酸性盐雾腐蚀后镍硅氮化硼涂层的可磨耗性能转变研究

Abradability Transformation of NiSi-BN Coating after Acid Salt Spray Corrosion

采用大气等离子喷涂制备镍硅氮化硼(NiSi-BN)可磨耗封严涂层并进行酸性盐雾192 h腐蚀处理。对腐蚀前后涂层的组织结构、硬度、结合强度进行分析。采用高温超高速可磨耗试验机研究腐蚀前后的涂层在650℃下与GH4169叶片的可磨耗刮削行为的差异性。研究结果表明:酸性盐雾腐蚀后NiSi-BN涂层的平均硬度由(11.9±0.40)HBW升高为(18.2±1.7)HBW,平均结合强度为变化不大,为(6.7±1.5)MPa,IDR值由腐蚀前10.77%±0.74%升高至26.70%±4.60%,酸性盐雾腐蚀192 h后NiSi-BN涂层的可磨耗性能出现明显下降。这主要是由于腐蚀区域涂层的硬度较高,造成叶片的磨损高度由腐蚀前的(0.05±0.01)mm增加至腐蚀后的(0.12±0.03)mm,对偶叶片与涂层间的摩擦作用更为剧烈,进而腐蚀态涂层的IDR值出现升高,涂层的可磨耗性能降低。

NiSi-BN abradable seal coating was prepared by atmospheric plasma spraying,and subjected to acid salt spray corrosion treatment for 192 hours.The microstructure,hardness,and bonding strength of the coating before and after corrosion were analyzed.The difference of abrasive scraping behavior between GH4169 blades and coating before and after corrosion at 650℃was studied by high temperature ultra-high speed abrasive testing machine.The results indicate that the average hardness of the NiSi-BN coating after acid salt spray corrosion increases from(11.9±0.4)HBW to(18.2±1.7)HBW,and the average bonding strength remains unchanged at(6.7±1.5)MPa.The average IDR value of corroded NiSi-BN coatings increases from 10.77%±0.74%to 26.70%±4.60%.The abradability of the NiSi-BN coatings drops significantly after acid salt spray corrosion for 192 hours.This is mainly due to the high hardness of the corrosive areas on the top of coating.The hard corrosive areas of corroded coatings cause relatively higher wear height on the blades than the as-sprayed coatings during the abradable scraping process.The wear height of the blades increases from(0.05±0.01)mm before corrosion to(0.12±0.03)mm after corrosion,resulting in an increase in the IDR value of the corroded coating.The abradability of NiSi-BN coating after salt spray corrosion for 192 hours has deteriorated.