Abstract: In order to prolong the service life of ZrO₂ thermal barrier coatings,HS188 alloy was used as the substrate,and NiCrAlY powder (base layer,d₅₀=106 μm) and yttria stabilized zirconia (YSZ,d₅₀=50 μm) were employed as sprayed feeder to prepare NiCrAlY+YSZ thermal barrier coatings using high-energy plasma spraying equipment with a progressive exploration method.The microstructure of the coatings was controlled by adjusting the stand-off distance (85,95,105 and 115 mm) and air-cooling manner (rear air cooling,rear air cooling+gun cooling,front air cooling,and front air cooling+gun cooling).The bonding strength of the coatings was evaluated by the drawing method.The results indicate that under the conditions of long stand-off distance and low cooling rate,it is difficult for the coatings to form a vertical crack structure due to the low instantaneous heating temperature and insufficient quenching on the sample surface.However,when the instantaneous heating temperature reaches the critical value and the air cooling rate is excessive,un-melted spray particles exist.When the stand-off distance is 85 mm and the cooling method is front air cooling,a thermal barrier ceramic coating with vertical crack morphology was obtained on HS188 alloy.Simultaneously,it has a moderate density of vertical cracks,the highest bonding strength and the best toughness.

Key words: high-energy plasma spraying, thermal barrier coating, NiCrAlY, zirconia, air cooling, stand-off distance

摘要： 为延长氧化钇稳定氧化锆热障涂层的使用寿命,通过高能等离子喷涂设备,以HS188合金为基体,NiCrAlY 粉(打底层,d₅₀=106 μm)和氧化钇稳定的氧化锆粉(YSZ,d₅₀=50 μm)为喷涂料,采用递进式的探索方法,通过调整枪基距(85、95、105和115 mm)和冷却方式(后风冷、后风冷+枪冷、前风冷、前风冷+枪冷)来控制涂层的组织结构,并采用拉拔法评价NiCrAlY+YSZ涂层的结合强度。结果表明:在枪基距较远以及冷却速率较低的情况下,因试样表面瞬热温度较低和激冷不足,涂层难以形成垂直裂纹结构。然而,在瞬热温度达到要求,风冷速率过度的情况下,会出现喷涂颗粒未熔的现象。当枪基距为85 mm,冷却方式为前风冷时,在HS188合金上获得了垂直裂纹形貌的热障陶瓷涂层,同时涂层的垂直裂纹密度适中,结合强度最高,韧性也最好。

关键词: 高能等离子喷涂, 热障涂层, NiCrAlY, 氧化锆, 风冷, 枪基距